Objective correlate of subjective pain perception by contact heat-evoked potentials.

PubMed

Granovsky, Yelena; Granot, Michal; Nir, Rony-Reuven; Yarnitsky, David

2008-01-01

The method of pain-evoked potentials has gained considerable acceptance over the last 3 decades regarding its objectivity, repeatability, and quantifiability. The present study explored whether the relationship between pain-evoked potentials and pain psychophysics obtained by contact heat stimuli is similar to those observed for the conventionally used laser stimulation. Evoked potentials (EPs) were recorded in response to contact heat stimuli at different body sites in 24 healthy volunteers. Stimuli at various temperatures were applied to the forearm (43 degrees C, 46 degrees C, 49 degrees C, and 52 degrees C) and leg (46 degrees C and 49 degrees C). The amplitudes of both components (N2 and P2) were strongly associated with the intensity of the applied stimuli and with subjective pain perception. Yet, regression analysis revealed pain perception and not stimulus intensity as the major contributing factor. A significant correlation was found between the forearm and the leg for both psychophysics and EPs amplitude. Contact heat can generate readily distinguishable evoked potentials on the scalp, consistent between upper and lower limbs. Although these potentials bear positive correlation with both stimulus intensity and pain magnitude, the latter is the main contributor to the evoked brain response.

Evoked potentials in multiple sclerosis.

PubMed

Kraft, George H

2013-11-01

Before the development of magnetic resonance imaging (MRI), evoked potentials (EPs)-visual evoked potentials, somatosensory evoked potentials, and brain stem auditory evoked responses-were commonly used to determine a second site of disease in patients being evaluated for possible multiple sclerosis (MS). The identification of an area of the central nervous system showing abnormal conduction was used to supplement the abnormal signs identified on the physical examination-thus identifying the "multiple" in MS. This article is a brief overview of additional ways in which central nervous system (CNS) physiology-as measured by EPs-can still contribute value in the management of MS in the era of MRIs. Copyright © 2013 Elsevier Inc. All rights reserved.

Unisensory processing and multisensory integration in schizophrenia: a high-density electrical mapping study.

PubMed

Stone, David B; Urrea, Laura J; Aine, Cheryl J; Bustillo, Juan R; Clark, Vincent P; Stephen, Julia M

2011-10-01

In real-world settings, information from multiple sensory modalities is combined to form a complete, behaviorally salient percept - a process known as multisensory integration. While deficits in auditory and visual processing are often observed in schizophrenia, little is known about how multisensory integration is affected by the disorder. The present study examined auditory, visual, and combined audio-visual processing in schizophrenia patients using high-density electrical mapping. An ecologically relevant task was used to compare unisensory and multisensory evoked potentials from schizophrenia patients to potentials from healthy normal volunteers. Analysis of unisensory responses revealed a large decrease in the N100 component of the auditory-evoked potential, as well as early differences in the visual-evoked components in the schizophrenia group. Differences in early evoked responses to multisensory stimuli were also detected. Multisensory facilitation was assessed by comparing the sum of auditory and visual evoked responses to the audio-visual evoked response. Schizophrenia patients showed a significantly greater absolute magnitude response to audio-visual stimuli than to summed unisensory stimuli when compared to healthy volunteers, indicating significantly greater multisensory facilitation in the patient group. Behavioral responses also indicated increased facilitation from multisensory stimuli. The results represent the first report of increased multisensory facilitation in schizophrenia and suggest that, although unisensory deficits are present, compensatory mechanisms may exist under certain conditions that permit improved multisensory integration in individuals afflicted with the disorder. Copyright © 2011 Elsevier Ltd. All rights reserved.

Binaural Interaction in Specific Language Impairment: An Auditory Evoked Potential Study

ERIC Educational Resources Information Center

Clarke, Elaine M; Adams, Catherine

2007-01-01

The aim of the study was to examine whether auditory binaural interaction, defined as any difference between binaurally evoked responses and the sum of monaurally evoked responses, which is thought to index functions involved in the localization and detection of signals in background noise, is atypical in a group of children with specific language…

Augmenting responses evoked in area 17 of the cat by intracortical axon collaterals of cortico-geniculate cells.

PubMed Central

Ferster, D; Lindström, S

1985-01-01

Evoked potentials were recorded in the visual cortex of the cat after electrical stimulation of the lateral geniculate nucleus (l.g.n.). The primary response, mediated by geniculo-cortical fibres, was depressed at stimulation frequencies above 7 Hz and replaced by a late potential, the incremental response, which gradually increased in amplitude with successive stimuli. The incremental response was a negative-positive potential in the depth of the cortex with the negative component having maximal amplitude in layer 4. The response reversed polarity in layer 1 to become a positive-negative potential at the surface. The latency of the negative component of the incremental response was about 3.5-4 ms in layer 4, compared to about 1.5 and 2.5 ms for the mono- and disynaptic components of the primary response. The incremental response could only be evoked from the l.g.n. and the optic radiation, not from the optic tract, superior colliculus or other surrounding structures. Within the l.g.n., the effect was only evoked from stimulation sites in approximate retinotopic register with the recording site in the cortex. Low threshold points were found in the A laminae, completely overlapping with the low threshold points for the primary response. Thresholds increased steeply when the stimulation electrode was lowered into the C laminae. The incremental response could still be evoked ten days after the destruction of all cells in the l.g.n. complex by kainic acid. It is concluded that the described incremental response is identical to the augmenting response of Dempsey & Morison (1943) and is mediated by intracortical axon collaterals of antidromically activated cortico-geniculate neurones. Images Plate 1 PMID:4057097

A new method for registration of kinesthetic evoked potentials for studies of proprioceptive sensitivity in normal subjects and patients with organic lesions in the brain.

PubMed

Gordeev, S A; Voronin, S G

2015-01-01

The proprioceptive sensitivity of healthy volunteers and convalescents after acute cerebrovascular episodes was studied by a new neurophysiological method for registration of kinesthetic evoked potentials emerging in response to passive 50(o) bending of the hand in the wrist joint with the angular acceleration of 350 rad/sec(2). Kinesthetic evoked potentials were recorded above the somatosensory cortex projection areas in the hemispheres contra- and ipsilateral to the stimulated limb. The patients exhibited significantly longer latencies and lesser amplitudes of the early components of response in the involved hemisphere in comparison with normal subjects. The method for registration of the kinesthetic evoked potentials allows a more detailed study of the mechanisms of kinesthetic sensitivity in health and in organic involvement of the brain.

Combined ocular and cervical vestibular evoked myogenic potential in individuals with vestibular hyporeflexia and in patients with Ménière's disease.

PubMed

Silva, Tatiana Rocha; de Resende, Luciana Macedo; Santos, Marco Aurélio Rocha

The vestibular evoked myogenic potential is a potential of mean latency that measures the muscle response to auditory stimulation. This potential can be generated from the contraction of the sternocleidomastoid muscle and also from the contraction of extraocular muscles in response to high-intensity sounds. This study presents a combined or simultaneous technique of cervical and ocular vestibular evoked myogenic potential in individuals with changes in the vestibular system, for use in otoneurologic diagnosis. To characterize the records and analyze the results of combined cervical and ocular VEMP in individuals with vestibular hyporeflexia and in those with Ménière's disease. The study included 120 subjects: 30 subjects with vestibular hyporeflexia, 30 with Ménière's disease, and 60 individuals with normal hearing. Data collection was performed by simultaneously recording the cervical and ocular vestibular evoked myogenic potential. There were differences between the study groups (individuals with vestibular hyporeflexia and individuals with Ménière's disease) and the control group for most of wave parameters in combined cervical and ocular vestibular evoked myogenic potential. For cervical vestibular evoked myogenic potential, it was observed that the prolongation of latency of the P13 and N23 waves was the most frequent finding in the group with vestibular hyporeflexia and in the group with Ménière's disease. For ocular vestibular evoked myogenic potential, prolonged latency of N10 and P15 waves was the most frequent finding in the study groups. Combined cervical and ocular vestibular evoked myogenic potential presented relevant results for individuals with vestibular hyporeflexia and for those with Ménière's disease. There were differences between the study groups and the control group for most of the wave parameters in combined cervical and ocular vestibular evoked myogenic potential. Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Origin and Properties of Striatal Local Field Potential Responses to Cortical Stimulation: Temporal Regulation by Fast Inhibitory Connections

PubMed Central

Galiñanes, Gregorio L.; Braz, Barbara Y.; Murer, Mario Gustavo

2011-01-01

Evoked striatal field potentials are seldom used to study corticostriatal communication in vivo because little is known about their origin and significance. Here we show that striatal field responses evoked by stimulating the prelimbic cortex in mice are reduced by more than 90% after infusing the AMPA receptor antagonist CNQX close to the recording electrode. Moreover, the amplitude of local field responses and dPSPs recorded in striatal medium spiny neurons increase in parallel with increasing stimulating current intensity. Finally, the evoked striatal fields show several of the basic known properties of corticostriatal transmission, including paired pulse facilitation and topographical organization. As a case study, we characterized the effect of local GABAA receptor blockade on striatal field and multiunitary action potential responses to prelimbic cortex stimulation. Striatal activity was recorded through a 24 channel silicon probe at about 600 µm from a microdialysis probe. Intrastriatal administration of the GABAA receptor antagonist bicuculline increased by 65±7% the duration of the evoked field responses. Moreover, the associated action potential responses were markedly enhanced during bicuculline infusion. Bicuculline enhancement took place at all the striatal sites that showed a response to cortical stimulation before drug infusion, but sites showing no field response before bicuculline remained unresponsive during GABAA receptor blockade. Thus, the data demonstrate that fast inhibitory connections exert a marked temporal regulation of input-output transformations within spatially delimited striatal networks responding to a cortical input. Overall, we propose that evoked striatal fields may be a useful tool to study corticostriatal synaptic connectivity in relation to behavior. PMID:22163020

Effect of combined opioid receptor and α2-adrenoceptor blockade on anxiety and electrically evoked startle responses.

PubMed

Vo, Lechi; Drummond, Peter D

2017-06-01

The R3 component of the electrically evoked blink reflex may form part of a startle reaction. Acoustic startle responses are augmented by yohimbine, an α 2 -adrenoceptor antagonist that blocks α 2 -autoreceptors, and are potentiated by opioid receptor blockade. To investigate these influences on electrically evoked startle responses, 16 mg yohimbine, with (16 participants) or without 50 mg naltrexone (23 participants), was administered in separate double-blind placebo-controlled cross-over experiments. In each experiment, R3 (a probable component of the startle response) was examined before and after high-frequency electrical stimulation of the forearm, a procedure that initiates inhibitory pain controls. Anxiety and somatic symptoms were greater after yohimbine than placebo, and were potentiated by naltrexone. Pain ratings for the electrically evoked startle stimuli decreased after high-frequency electrical stimulation in the placebo session but remained stable after drug administration. Yohimbine with naltrexone, but not yohimbine alone, also blocked an inhibitory effect of high-frequency electrical stimulation on electrically evoked sharp sensations and R3. Together, the findings suggest that adding naltrexone to yohimbine potentiated anxiety and blocked inhibitory influences of high-frequency electrical stimulation on electrically evoked sensations and startle responses. Thus, opioid peptides could reduce activity in nociceptive and startle-reflex pathways, or inhibit crosstalk between these pathways. Failure of this inhibitory opioid influence might be important in chronically painful conditions that are aggravated by startle stimuli.

Neural Dynamics Underlying Event-Related Potentials

NASA Technical Reports Server (NTRS)

Shah, Ankoor S.; Bressler, Steven L.; Knuth, Kevin H.; Ding, Ming-Zhou; Mehta, Ashesh D.; Ulbert, Istvan; Schroeder, Charles E.

2003-01-01

There are two opposing hypotheses about the brain mechanisms underlying sensory event-related potentials (ERPs). One holds that sensory ERPs are generated by phase resetting of ongoing electroencephalographic (EEG) activity, and the other that they result from signal averaging of stimulus-evoked neural responses. We tested several contrasting predictions of these hypotheses by direct intracortical analysis of neural activity in monkeys. Our findings clearly demonstrate evoked response contributions to the sensory ERP in the monkey, and they suggest the likelihood that a mixed (Evoked/Phase Resetting) model may account for the generation of scalp ERPs in humans.

Phantom somatosensory evoked potentials following selective intraneural electrical stimulation in two amputees.

PubMed

Granata, Giuseppe; Di Iorio, Riccardo; Romanello, Roberto; Iodice, Francesco; Raspopovic, Stanisa; Petrini, Francesco; Strauss, Ivo; Valle, Giacomo; Stieglitz, Thomas; Čvančara, Paul; Andreu, David; Divoux, Jean-Louis; Guiraud, David; Wauters, Loic; Hiairrassary, Arthur; Jensen, Winnie; Micera, Silvestro; Rossini, Paolo Maria

2018-06-01

The aim of the paper is to objectively demonstrate that amputees implanted with intraneural interfaces are truly able to feel a sensation in the phantom hand by recording "phantom" somatosensory evoked potentials from the corresponding brain areas. We implanted four transverse intrafascicular multichannel electrodes, available with percutaneous connections to a multichannel electrical stimulator, in the median and ulnar nerves of two left trans-radial amputees. Two channels of the implants that were able to elicit sensations during intraneural nerve stimulation were chosen, in both patients, for recording somatosensory evoked potentials. We recorded reproducible evoked responses by stimulating the median and the ulnar nerves in both cases. Latencies were in accordance with the arrival of somatosensory information to the primary somatosensory cortex. Our results provide evidence that sensations generated by intraneural stimulation are truly perceived by amputees and located in the phantom hand. Moreover, our results strongly suggest that sensations perceived in different parts of the phantom hand result in different evoked responses. Somatosensory evoked potentials obtained by selective intraneural electrical stimulation in amputee patients are a useful tool to provide an objective demonstration of somatosensory feedback in new generation bidirectional prostheses. Copyright © 2018. Published by Elsevier B.V.

Spectrum pattern resolution after noise exposure in a beluga whale, Delphinapterus leucas: Evoked potential study.

PubMed

Popov, Vladimir V; Nechaev, Dmitry I; Sysueva, Evgenia V; Rozhnov, Viatcheslav V; Supin, Alexander Ya

2015-07-01

Temporary threshold shift (TTS) and the discrimination of spectrum patterns after fatiguing noise exposure (170 dB re 1 μPa, 10 min duration) was investigated in a beluga whale, Delphinapterus leucas, using the evoked potential technique. Thresholds were measured using rhythmic (1000/s) pip trains of varying levels and recording the rhythmic evoked responses. Discrimination of spectrum patterns was investigated using rippled-spectrum test stimuli of various levels and ripple densities, recording the rhythmic evoked responses to ripple phase reversals. Before noise exposure, the greatest responses to rippled-spectrum probes were evoked by stimuli with a low ripple density with a decrease in the response magnitude occurring with an increasing ripple density. After noise exposure, both a TTS and a reduction of the responses to rippled-spectrum probes appeared and recovered in parallel. The reduction of the responses to rippled-spectrum probes was maximal for high-magnitude responses at low ripple densities and was negligible for low-magnitude responses at high ripple densities. It is hypothesized that the impacts of fatiguing sounds are not limited by increased thresholds and decreased sensitivity results in reduced ability to discriminate fine spectral content with the greatest impact on the discrimination of spectrum content that may carry the most obvious information about stimulus properties.

Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats.

PubMed

Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin

2016-03-01

Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI. Copyright © 2015 Elsevier Ltd. All rights reserved.

Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz tone pips.

PubMed

Todd, N P M; Paillard, A C; Kluk, K; Whittle, E; Colebatch, J G

2014-06-01

Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulation and by conducting a source analysis of the resulting evoked potentials of short and long latency. Ten healthy, right-handed subjects were recruited and evoked potentials were recorded to both left- and right-ear sound stimulation, above and below vestibular threshold. Below VEMP threshold, typical AEPs were recorded, consisting of mid-latency (MLR) waves Na and Pa followed by long latency AEPs (LAEPs) N1 and P2. In the supra-threshold condition, the expected changes in morphology were observed, consisting of: (1) short-latency vestibular evoked potentials (VsEPs) which have no auditory correlate, i.e. the ocular VEMP (OVEMP) and inion response related potentials; (2) a later deflection, labelled N42/P52, followed by the LAEPs N1 and P2. Statistical analysis of the vestibular dependent responses indicated a contralateral effect for inion related short-latency responses and a left-ear/right-hemisphere advantage for the long-latency responses. Source analysis indicated that the short-latency effects may be mediated by a contralateral projection to left cerebellum, while the long-latency effects were mediated by a contralateral projection to right cingulate cortex. In addition we found evidence of a possible vestibular contribution to the auditory T-complex in radial temporal lobe sources. These last results raise the possibility that acoustic activation of the otolith organs could potentially contribute to auditory processing. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials.

PubMed

La Cesa, S; Di Stefano, G; Leone, C; Pepe, A; Galosi, E; Alu, F; Fasolino, A; Cruccu, G; Valeriani, M; Truini, A

2018-01-01

In the neurophysiological assessment of patients with neuropathic pain, laser evoked potentials (LEPs), contact heat evoked potentials (CHEPs) and the evoked potentials by the intraepidermal electrical stimulation via concentric needle electrode are widely agreed as nociceptive specific responses; conversely, the nociceptive specificity of evoked potentials by surface concentric electrode (SE-PREPs) is still debated. In this neurophysiological study we aimed at verifying the nociceptive specificity of SE-PREPs. We recorded LEPs, CHEPs and SE-PREPs in eleven healthy participants, before and after epidermal denervation produced by prolonged capsaicin application. We also used skin biopsy to verify the capsaicin-induced nociceptive nerve fibre loss in the epidermis. We found that whereas LEPs and CHEPs were suppressed after capsaicin-induced epidermal denervation, the surface concentric electrode stimulation of the same denervated skin area yielded unchanged SE-PREPs. The suppression of LEPs and CHEPs after nociceptive nerve fibre loss in the epidermis indicates that these techniques are selectively mediated by nociceptive system. Conversely, the lack of SE-PREP changes suggests that SE-PREPs do not provide selective information on nociceptive system function. Capsaicin-induced epidermal denervation abolishes laser evoked potentials (LEPs) and contact heat evoked potentials (CHEPs), but leaves unaffected pain-related evoked potentials by surface concentric electrode (SE-PREPs). These findings suggest that unlike LEPs and CHEPs, SE-PREPs are not selectively mediated by nociceptive system. © 2017 European Pain Federation - EFIC®.

Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants.

PubMed

Caldas, Fernanda Ferreira; Cardoso, Carolina Costa; Barreto, Monique Antunes de Souza Chelminski; Teixeira, Marina Santos; Hilgenberg, Anacléia Melo da Silva; Serra, Lucieny Silva Martins; Bahmad Junior, Fayez

2016-01-01

The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. There were significant differences in follow-up time (p=0.0082) and electrode position (p=0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p=0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Visual evoked potential in RCS rats with Okayama University-type retinal prosthesis (OUReP™) implantation.

PubMed

Alamusi; Matsuo, Toshihiko; Hosoya, Osamu; Uchida, Tetsuya

2017-06-01

Photoelectric dye-coupled polyethylene film, designated Okayama University type-retinal prosthesis or OUReP™, generates light-evoked surface electric potentials and stimulates neurons. The dye-coupled films or plain films were implanted subretinally in both eyes of 10 Royal College of Surgeons rats with hereditary retinal dystrophy at the age of 6 weeks. Visual evoked potentials in response to monocular flashing light stimuli were recorded from cranially-fixed electrodes, 4 weeks and 8 weeks after the implantation. After the recording, subretinal film implantation was confirmed histologically in 7 eyes with dye-coupled films and 7 eyes with plain films. The recordings from these 7 eyes in each group were used for statistical analysis. The amplitudes of visual evoked potentials in the consecutive time points from 125 to 250 ms after flash were significantly larger in the 7 eyes with dye-coupled film implantation, compared to the 7 eyes with plain film implantation at 8 weeks after the implantation (P < 0.05, repeated-measure ANOVA). The photoelectric dye-coupled polyethylene film, as retinal prosthesis, gave rise to visual evoked potential in response to flashing light.

Evoked potential application to study of echolocation in cetaceans

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nactigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

2002-05-01

The evoked-potential (EP) method is effective in studies of hearing capabilities of cetaceans. However, until now EP studies in cetaceans were performed only in conditions of passive hearing by recording EP to external stimuli. Can this method be applied to study active echolocation in odontocetes? To answer this question, auditory brainstem evoked responses (ABR) were recorded in a false killer whale while the animal echolocated a target within an experiment in which the animal reported the target present or absent. The ABR collection was triggered by echolocation clicks. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation has shown that the first set of waves is a response to the emitted click whereas the second one is a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds of more than 40 dB near the animal's head. This finding indicates some mechanisms releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

Characterization of Motor and Somatosensory Evoked Potentials in the Yucatan Micropig Using Transcranial and Epidural Stimulation.

PubMed

Benavides, Francisco D; Santamaria, Andrea J; Bodoukhin, Nikita; Guada, Luis G; Solano, Juan P; Guest, James D

2017-09-15

Yucatan micropigs have brain and spinal cord dimensions similar to humans and are useful for certain spinal cord injury (SCI) translational studies. Micropigs are readily trained in behavioral tasks, allowing consistent testing of locomotor loss and recovery. However, there has been little description of their motor and sensory pathway neurophysiology. We established methods to assess motor and sensory cortical evoked potentials in the anesthetized, uninjured state. We also evaluated epidurally evoked motor and sensory stimuli from the T6 and T9 levels, spanning the intended contusion injury epicenter. Response detection frequency, mean latency and amplitude values, and variability of evoked potentials were determined. Somatosensory evoked potentials were reliable and best detected during stimulation of peripheral nerve and epidural stimulation by referencing the lateral cortex to midline Fz. The most reliable hindlimb motor evoked potential (MEP) occurred in tibialis anterior. We found MEPs in forelimb muscles in response to thoracic epidural stimulation likely generated from propriospinal pathways. Cranially stimulated MEPs were easier to evoke in the upper limbs than in the hindlimbs. Autopsy studies revealed substantial variations in cortical morphology between animals. This electrophysiological study establishes that neurophysiological measures can be reliably obtained in micropigs in a time frame compatible with other experimental procedures, such as SCI and transplantation. It underscores the need to better understand the motor control pathways, including the corticospinal tract, to determine which therapeutics are suitable for testing in the pig model.

Gender differences in binaural speech-evoked auditory brainstem response: are they clinically significant?

PubMed

Jalaei, Bahram; Azmi, Mohd Hafiz Afifi Mohd; Zakaria, Mohd Normani

2018-05-17

Binaurally evoked auditory evoked potentials have good diagnostic values when testing subjects with central auditory deficits. The literature on speech-evoked auditory brainstem response evoked by binaural stimulation is in fact limited. Gender disparities in speech-evoked auditory brainstem response results have been consistently noted but the magnitude of gender difference has not been reported. The present study aimed to compare the magnitude of gender difference in speech-evoked auditory brainstem response results between monaural and binaural stimulations. A total of 34 healthy Asian adults aged 19-30 years participated in this comparative study. Eighteen of them were females (mean age=23.6±2.3 years) and the remaining sixteen were males (mean age=22.0±2.3 years). For each subject, speech-evoked auditory brainstem response was recorded with the synthesized syllable /da/ presented monaurally and binaurally. While latencies were not affected (p>0.05), the binaural stimulation produced statistically higher speech-evoked auditory brainstem response amplitudes than the monaural stimulation (p<0.05). As revealed by large effect sizes (d>0.80), substantive gender differences were noted in most of speech-evoked auditory brainstem response peaks for both stimulation modes. The magnitude of gender difference between the two stimulation modes revealed some distinct patterns. Based on these clinically significant results, gender-specific normative data are highly recommended when using speech-evoked auditory brainstem response for clinical and future applications. The preliminary normative data provided in the present study can serve as the reference for future studies on this test among Asian adults. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Oscillatory frontal theta responses are increased upon bisensory stimulation.

PubMed

Sakowitz, O W; Schürmann, M; Başar, E

2000-05-01

To investigate the functional correlation of oscillatory EEG components with the interaction of sensory modalities following simultaneous audio-visual stimulation. In an experimental study (15 subjects) we compared auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) to bimodal evoked potentials (BEPs; simultaneous auditory and visual stimulation). BEPs were assumed to be brain responses to complex stimuli as a marker for intermodal associative functioning. Frequency domain analysis of these EPs showed marked theta-range components in response to bimodal stimulation. These theta components could not be explained by linear addition of the unimodal responses in the time domain. Considering topography the increased theta-response showed a remarkable frontality in proximity to multimodal association cortices. Referring to methodology we try to demonstrate that, even if various behavioral correlates of brain oscillations exist, common patterns can be extracted by means of a systems-theoretical approach. Serving as an example of functionally relevant brain oscillations, theta responses could be interpreted as an indicator of associative information processing.

Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer.

PubMed

Xu, Yin-Hua; Zhang, Guang-Jian; Zhao, Jing-Tong; Chu, Chun-Ping; Li, Yu-Zi; Qiu, De-Lai

2017-11-01

The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC 50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials.

PubMed

Jones, Matthew D; Taylor, Janet L; Booth, John; Barry, Benjamin K

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1-SEPs; Experiment 2-LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = -0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

[A Case of Left Vertebral Artery Aneurysm Showing Evoked Potentials on Bilateral Electrode by the Left Vagus Nerve Stimulation to Electromyographic Tracheal Tube].

PubMed

Kadoya, Tatsuo; Uehara, Hirofumi; Yamamoto, Toshinori; Shiraishi, Munehiro; Kinoshita, Yuki; Joyashiki, Takeshi; Enokida, Kengo

2016-02-01

Previously, we reported a case of brainstem cavernous hemangioma showing false positive responses to electromyographic tracheal tube (EMG tube). We concluded that the cause was spontaneous respiration accompanied by vocal cord movement. We report a case of left vertebral artery aneurysm showing evoked potentials on bilateral electrodes by the left vagus nerve stimulation to EMG tube. An 82-year-old woman underwent clipping of a left unruptured vertebral artery-posterior inferior cerebellar artery aneurysm. General anesthesia was induced with remifentanil, propofol and suxamethonium, and was maintained with oxygen, air, remifentanil and propofol. We monitored somatosensory evoked potentials, motor evoked potentials, and electromyogram of the vocal cord. When the manipulation reached brainstem and the instrument touched the left vagus nerve, evoked potentials appeared on bilateral electrodes. EMG tube is equipped with two electrodes on both sides. We concluded that the left vagus nerve stimulation generated evoked potentials of the left laryngeal muscles, and they were simultaneously detected as potential difference between two electrodes on both sides. EMG tube is used to identify the vagus nerve. However, it is necessary to bear in mind that each vagus nerve stimulation inevitably generates evoked potentials on bilateral electrodes.

Corticomotor excitability during a noxious stimulus before and after exercise in women with fibromyalgia.

PubMed

Hoeger Bement, Marie K; Weyer, Andy D; Yoon, Tejin; Hunter, Sandra K

2014-02-01

The purposes of this study were to assess corticomotor excitability in people with fibromyalgia during a noxious stimulus before and after fatiguing exercise and examine associations with pain perception. Fifteen women with fibromyalgia completed three sessions: one familiarization and two experimental. The experimental sessions were randomized and involved measurement of pain perception and motor evoked potentials before and after (1) quiet rest and (2) isometric contraction of the elbow flexor muscles. Motor evoked potential amplitude of brachioradialis muscle was measured following transcranial magnetic stimulation delivered before, during, and after a noxious mechanical stimulus. After quiet rest, there was no change in pain perception. After the submaximal contraction, there was considerable variability in the pain response. Based on the changes in the experimental pain, subjects were divided into three groups (increase, decrease, and no change in pain). There was an interaction between pain response and the pain-induced change in motor evoked potentials. Those individuals who had an increase in motor evoked potentials during the pain test had an increase in pain after exercise. Thus, women with fibromyalgia were classified based on their pain response to exercise, and this response was associated with the change in corticomotor excitability during the application of a noxious stimulus.

Effects of maternal inhalation of gasoline evaporative ...

EPA Pesticide Factsheets

In order to assess potential health effects resulting from exposure to ethanol-gasoline blend vapors, we previously conducted neurophysiological assessment of sensory function following gestational exposure to 100% ethanol vapor (Herr et al., Toxicologist, 2012). For comparison purposes, the current study investigated the same measures after gestational exposure to 100% gasoline evaporative condensates (GVC). Pregnant Long-Evans rats were exposed to 0, 3K, 6K, or 9K ppm GVC vapors for 6.5 h/day over GD9 – GD20. Sensory evaluations of male offspring began around PND106. Peripheral nerve function (compound action potentials, NCV), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEP), VEP contrast sensitivity, and electroretinograms (ERG) recorded from dark-adapted (scotopic) and light-adapted (photopic) flashes, and UV and green flicker. Although some minor statistical differences were indicated for auditory and somatosensory responses, these changes were not consistently dose- or stimulus intensity-related. Scotopic ERGs had a statistically significant dose-related decrease in the b-wave implicit time. All other parameters of ERGs and VEPs were unaffected by treatment. All physiological responses showed changes related to stimulus intensity, and provided an estimate of detectable le

Generalized alternating stimulation: a novel method to reduce stimulus artifact in electrically evoked compound action potentials.

PubMed

Alvarez, Isaac; de la Torre, Angel; Sainz, Manuel; Roldan, Cristina; Schoesser, Hansjoerg; Spitzer, Philipp

2007-09-15

Stimulus artifact is one of the main limitations when considering electrically evoked compound action potential for clinical applications. Alternating stimulation (average of recordings obtained with anodic-cathodic and cathodic-anodic bipolar stimulation pulses) is an effective method to reduce stimulus artifact when evoked potentials are recorded. In this paper we extend the concept of alternating stimulation by combining anodic-cathodic and cathodic-anodic recordings with a weight in general different to 0.5. We also provide an automatic method to obtain an estimation of the optimal weights. Comparison with conventional alternating, triphasic stimulation and masker-probe paradigm shows that the generalized alternating method improves the quality of electrically evoked compound action potential responses.

On hemispheric differences in evoked potentials to speech stimuli

NASA Technical Reports Server (NTRS)

Galambos, R.; Benson, P.; Smith, T. S.; Schulman-Galambos, C.; Osier, H.

1975-01-01

Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks.

The Middle Latency Response (MLR) and Steady State Evoked Potential (SSEP) in Neonates.

DTIC Science & Technology

1985-05-01

diagnostic audiologic information will enhance habilitation efforts in prescribing hearing aids and designing appropriate language intervention strategies...auditory evoked brain stem response. A study of patients with sensory hearing loss. SCANDINAVIAN AUDIOLOGY 8: 67-70, 1979. Page 165 "- FILMED 10-85 DTIC * 4 N . . -. N

A comparison of auditory evoked potentials to acoustic beats and to binaural beats.

PubMed

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2010-04-01

The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to beats-evoked oscillations were determined and compared across beat types, beat frequencies and base (carrier) frequencies. All stimuli evoked tone-onset components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude in response to acoustic than to binaural beats, to 250 than to 1000 Hz base frequency and to 3 Hz than to 6 Hz beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left temporal lobe areas. Differences between estimated sources of potentials to acoustic and binaural beats were not significant. The perceptions of binaural beats involve cortical activity that is not different than acoustic beats in distribution and in the effects of beat- and base frequency, indicating similar cortical processing. Copyright 2010 Elsevier B.V. All rights reserved.

Stability of Evoked Potentials during Auditory Attention

DTIC Science & Technology

1988-12-01

attention ef- (S2), to which the subject made a behavioral response and fects upon NI components of the evoked potential received food reinforcement for a... food dipper mounted in the floor, and a driver, with a sound tube attached, mounted in the top of the box. Histology Four weeks after surgery, the cats...response paradigm dose of intravenous sodium pentobarbital. Electrolytic lesions were using food reinforcement. They were gradually deprived of food

Can Vestibular-Evoked Myogenic Potentials Help Differentiate Ménière Disease from Vestibular Migraine?

PubMed Central

Zuniga, M. Geraldine; Janky, Kristen L.; Schubert, Michael C.; Carey, John P.

2013-01-01

Objectives To characterize both cervical and ocular vestibular-evoked myogenic potential (cVEMP, oVEMP) responses to air-conducted sound (ACS) and midline taps in Ménière disease (MD), vestibular migraine (VM), and controls, as well as to determine if cVEMP or oVEMP responses can differentiate MD from VM. Study Design Prospective cohort study. Setting Tertiary referral center. Subjects and Methods Unilateral definite MD patients (n = 20), VM patients (n = 21) by modified Neuhauser criteria, and age-matched controls (n = 28). cVEMP testing used ACS (clicks), and oVEMP testing used ACS (clicks and 500-Hz tone bursts) and midline tap stimuli (reflex hammer and Mini-Shaker). Outcome parameters were cVEMP peak-to-peak amplitudes and oVEMP n10 amplitudes. Results Relative to controls, MD and VM groups both showed reduced click-evoked cVEMP (P < .001) and oVEMP (P < .001) amplitudes. Only the MD group showed reduction in tone-evoked amplitudes for oVEMP. Tone-evoked oVEMPs differentiated MD from controls (P = .001) and from VM (P = .007). The oVEMPs in response to the reflex hammer and Mini-Shaker midline taps showed no differences between groups (P > .210). Conclusions Using these techniques, VM and MD behaved similarly on most of the VEMP test battery. A link in their pathophysiology may be responsible for these responses. The data suggest a difference in 500-Hz tone burst–evoked oVEMP responses between MD and MV as a group. However, no VEMP test that was investigated segregated individuals with MD from those with VM. PMID:22267492

The ventricular intracardiac unipolar paced-evoked potential in an isolated animal heart.

PubMed

Economides, A P; Walton, C; Gergely, S

1988-02-01

The endocardial unipolar paced evoked response has excited a great deal of interest due to its possible use in the measurement of the metabolic state of the body and other pacer-related areas. Although rate-responsive pacing utilizing this signal has been clinically evaluated, little is known regarding the behavior of the components of this waveform under normal physiological conditions. We have developed an electronic circuit which allows the recording of the evoked response within a few milliseconds of a pacing stimulus of 5 V and 0.5 ms duration being applied using a single unipolar, smooth platinum electrode of 14 mm2 surface area. The paced evoked response was measured using a total of 20 isolated rabbit heart preparations. Five were run for 8 hours and the remaining fifteen were run for 5 hours. Our results indicate that the waveform components of the evoked response remain stable while the preparation is viable, but that two of the time-related measurements change with loss of viability. A significant lengthening of the stimulus-R interval was seen together with a dramatic shortening of the R-T period. The net result of these changes was an overall reduction of 17% in the complex duration. In addition, we found the R-T shortening to be a sensitive measure of myocardial integrity. We conclude that the combination of our interface charge elimination circuit and the isolated heart preparation has proved a useful system for the investigation of the paced evoked potential. Furthermore, the loss of myocardial viability has a complex action on this response.

Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials.

PubMed

Potas, Jason Robert; de Castro, Newton Gonçalves; Maddess, Ted; de Souza, Marcio Nogueira

2015-01-01

Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for studying evoked compound action potentials in neural regeneration studies.

Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials

PubMed Central

Potas, Jason Robert; de Castro, Newton Gonçalves; Maddess, Ted; de Souza, Marcio Nogueira

2015-01-01

Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for studying evoked compound action potentials in neural regeneration studies. PMID:26325291

Auditory fear conditioning modifies steady-state evoked potentials in the rat inferior colliculus.

PubMed

Lockmann, André Luiz Vieira; Mourão, Flávio Afonso Gonçalves; Moraes, Marcio Flávio Dutra

2017-08-01

The rat inferior colliculus (IC) is a major midbrain relay for ascending inputs from the auditory brain stem and has been suggested to play a key role in the processing of aversive sounds. Previous studies have demonstrated that auditory fear conditioning (AFC) potentiates transient responses to brief tones in the IC, but it remains unexplored whether AFC modifies responses to sustained periodic acoustic stimulation-a type of response called the steady-state evoked potential (SSEP). Here we used an amplitude-modulated tone-a 10-kHz tone with a sinusoidal amplitude modulation of 53.7 Hz-as the conditioning stimulus (CS) in an AFC protocol (5 CSs per day in 3 consecutive days) while recording local field potentials (LFPs) from the IC. In the preconditioning session ( day 1 ), the CS elicited prominent 53.7-Hz SSEPs. In the training session ( day 2 ), foot shocks occurred at the end of each CS (paired group) or randomized in the inter-CS interval (unpaired group). In the test session ( day 3 ), SSEPs markedly differed from preconditioning in the paired group: in the first two trials the phase to which the SSEP coupled to the CS amplitude envelope shifted ~90°; in the last two trials the SSEP power and the coherence of SSEP with the CS amplitude envelope increased. LFP power decreased in frequency bands other than 53.7 Hz. In the unpaired group, SSEPs did not change in the test compared with preconditioning. Our results show that AFC causes dissociated changes in the phase and power of SSEP in the IC. NEW & NOTEWORTHY Local field potential oscillations in the inferior colliculus follow the amplitude envelope of an amplitude-modulated tone, originating a neural response called the steady-state evoked potential. We show that auditory fear conditioning of an amplitude-modulated tone modifies two parameters of the steady-state evoked potentials in the inferior colliculus: first the phase to which the evoked oscillation couples to the amplitude-modulated tone shifts; subsequently, the evoked oscillation power increases along with its coherence with the amplitude-modulated tone. Copyright © 2017 the American Physiological Society.

Non-provocative diagnostics of photosensitivity using visual evoked potentials.

PubMed

Vermeulen, Joost; Kalitzin, Stiliyan; Parra, Jaime; Dekker, Erwin; Vossepoel, Albert; da Silva, Fernando Lopes

2008-04-01

Photosensitive epilepsy (PSE) is the most common form of reflex epilepsy. Usually, to find out whether a patient is sensitive, he/she is stimulated visually with, e.g. a stroboscopic light stimulus at variable frequency and intensity until a photo paroxysmal response (PPR) occurs. The research described in this work aims to find whether photosensitivity can be detected without provoking a PPR. Twenty-two subjects, 15 with known photosensitivity, were stimulated with visual stimuli that did not provoke a PPR. Using an "evoked response representation", 18 features were analytically derived from EEG signals. Single- and multi-feature classification paradigms were applied to extract those features that separate best subjects with PSE from controls. Two variables in the "evoked response representation", a frequency term and a goodness of fit term to a particular template, appeared to be best suited to make a prediction about the photosensitivity of a subject. Evoked responses appear to carry information about potential PSE. This result can be useful for screening patients for photosensitivity and it may also help to assess in a quantitative way the effectiveness of medical therapy.

INHIBITION OF BRAIN CHOLINESTERASE AND THE PHOTIC AFTER DISCHARGE OF FLASH EVOKED POTENTIALS PRODUCED BY CARBARYL IN LONG EVANS RATS.

EPA Science Inventory

Carbaryl is a widely used N-methyl carbamate pesticide that acts by inhibiting cholinesterases (ChE), which may lead to cholinergic toxicity. Flash evoked potentials (FEPs) are a neurophysiological response often used to detect central nervous system (CNS) changes following expos...

BRAIN CHOLINESTERASE INHIBITION PRODUCED BY PROPOXUR AND DEPRESSION OF THE PHOTIC AFTER DISCHARGE OF FLASH EVOKED POTENTIALS IN LONG EVANS RATS.

EPA Science Inventory

Propoxur is a widely used N-methyl carbamate pesticide that acts by inhibiting cholinesterases (ChE), which may lead to cholinergic toxicity. Flash evoked potentials (FEPs) are a neurophysiological response following stimulation of the visual system with flashes of light. They ar...

Patterned light flash evoked short latency activity in the visual system of visually normal and in amblyopic subjects.

PubMed

Sjöström, A; Abrahamsson, M

1994-04-01

In a previous experimental study on anaesthetized cat it was shown that a short latency (35-40 ms) cortical potential changed polarity due to the presence or absence of a pattern in the flash stimulus. The results suggested one pathway of neuronal activation in the cortex to a pattern that was within the level of resolution and another to patterns that were not. It was implied that a similar difference in impulse transmission to pattern and non-pattern stimuli may be recorded in humans. The present paper describes recordings of the short-latency visual evoked response to varying light flash checkerboard pattern stimuli of high intensity in visually normal and amblyopic children and adults. When stimulating the normal eye a visual evoked response potential with a peak latency between 35 to 40 ms showed a polarity change to patterned compared to non-patterned stimulation. The visual evoked response resolution limit could be correlated to a visual acuity of 0.5 and below. In amblyopic eyes the shift in polarity was recorded at the acuity limit level. The latency of the pattern depending potential was increased in patients with amblyopia compared to normal, but not directly related to amblyopic degree. It is concluded that the short latency, visual evoked response that mainly represents the retino-geniculo-cortical activation may be used to estimate visual resolution below 0.5 in acuity level.(ABSTRACT TRUNCATED AT 250 WORDS)

Single-trial extraction of cognitive evoked potentials by combination of third-order correlation and wavelet denoising.

PubMed

Zhang, Z; Tian, X

2005-01-01

The application of a recently proposed denoising implementation for obtaining cognitive evoked potentials (CEPs) at the single-trial level is shown. The aim of this investigation is to develop the technique of extracting CEPs by combining both the third-order correlation and the wavelet denoising methods. First, the noisy CEPs was passed through a finite impulse response filter whose impulse response is matched with the shape of the noise-free signal. It was shown that it is possible to estimate the filter impulse response on basis of a select third-order correlation slice (TOCS) of the input noisy CEPs. Second, the output from the third-order correlation filter is decomposed with bi-orthogonal splines at 5 levels. The CEPs is reconstructed by wavelet final approximation a5. We study its performance in simulated data as well as in cognitive evoked potentials of normal rat and Alzheimer's disease (AD) model rat. For the simulated data, the method gives a significantly better reconstruction of the single-trial cognitive evoked potentials responses in comparison with the simulated data. Moreover, with this approach we obtain a significantly better estimation of the amplitudes and latencies of the simulated CEPs. For the real data, the method clearly improves the visualization of single-trial CEPs. This allows the calculation of better averages as well as the study of systematic or unsystematic variations between trials.

Objective Assessment of Spectral Ripple Discrimination in Cochlear Implant Listeners Using Cortical Evoked Responses to an Oddball Paradigm

PubMed Central

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B.

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2 = 0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users. PMID:24599314

Objective assessment of spectral ripple discrimination in cochlear implant listeners using cortical evoked responses to an oddball paradigm.

PubMed

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2=0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users.

Steady-state evoked potentials possibilities for mental-state estimation

NASA Technical Reports Server (NTRS)

Junker, Andrew M.; Schnurer, John H.; Ingle, David F.; Downey, Craig W.

1988-01-01

The use of the human steady-state evoked potential (SSEP) as a possible measure of mental-state estimation is explored. A method for evoking a visual response to a sum-of-ten sine waves is presented. This approach provides simultaneous multiple frequency measurements of the human EEG to the evoking stimulus in terms of describing functions (gain and phase) and remnant spectra. Ways in which these quantities vary with the addition of performance tasks (manual tracking, grammatical reasoning, and decision making) are presented. Models of the describing function measures can be formulated using systems engineering technology. Relationships between model parameters and performance scores during manual tracking are discussed. Problems of unresponsiveness and lack of repeatability of subject responses are addressed in terms of a need for loop closure of the SSEP. A technique to achieve loop closure using a lock-in amplifier approach is presented. Results of a study designed to test the effectiveness of using feedback to consciously connect humans to their evoked response are presented. Findings indicate that conscious control of EEG is possible. Implications of these results in terms of secondary tasks for mental-state estimation and brain actuated control are addressed.

TRPM2 activation by cyclic ADP-ribose at body temperature is involved in insulin secretion

PubMed Central

Togashi, Kazuya; Hara, Yuji; Tominaga, Tomoko; Higashi, Tomohiro; Konishi, Yasunobu; Mori, Yasuo; Tominaga, Makoto

2006-01-01

There are eight thermosensitive TRP (transient receptor potential) channels in mammals, and there might be other TRP channels sensitive to temperature stimuli. Here, we demonstrate that TRPM2 can be activated by exposure to warm temperatures (>35°C) apparently via direct heat-evoked channel gating. β-NAD+- or ADP-ribose-evoked TRPM2 activity is robustly potentiated at elevated temperatures. We also show that, even though cyclic ADP-ribose (cADPR) does not activate TRPM2 at 25°C, co-application of heat and intracellular cADPR dramatically potentiates TRPM2 activity. Heat and cADPR evoke similar responses in rat insulinoma RIN-5F cells, which express TRPM2 endogenously. In pancreatic islets, TRPM2 is coexpressed with insulin, and mild heating of these cells evokes increases in both cytosolic Ca2+ and insulin release, which is KATP channel-independent and protein kinase A-mediated. Heat-evoked responses in both RIN-5F cells and pancreatic islets are significantly diminished by treatment with TRPM2-specific siRNA. These results identify TRPM2 as a potential molecular target for cADPR, and suggest that TRPM2 regulates Ca2+ entry into pancreatic β-cells at body temperature depending on the production of cADPR-related molecules, thereby regulating insulin secretion. PMID:16601673

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

PubMed Central

Jones, Matthew D.; Taylor, Janet L.; Booth, John; Barry, Benjamin K.

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1–SEPs; Experiment 2–LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = −0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = −0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = −0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = −0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia. PMID:27965587

Vestibular evoked myogenic potential (VEMP) in patients with acoustic neuromas.

PubMed

Takeichi, N; Sakamoto, T; Fukuda, S; Inuyama, Y

2001-05-01

To study the utility of VEMP (vestibular-evoked myogenic potential) in the diagnosis of acoustic neuromas. Eighteen patients with unilateral acoustic neuromas were subjected to this study. Myogenic potential responding to loud click stimuli was recorded at ipsilateral sternocleidomastoid muscle. A normal range of VEMP was obtained from 20 controls. VEMP responses were compared with both, clinical symptoms and results of caloric tests. Thirteen out of 18 patients showed decreased responses of VEMP at the affected side. VEMP responses seemed to have little relation with dysequilibrium, spontaneous nystagmus, canal paresis and pure-tone hearing. VEMP is useful for detecting dysfunction of inferior vestibular nerve in patients with acoustic neuromas.

Surgical monitoring with auditory evoked potentials.

PubMed

Lüders, H

1988-07-01

This comprehensive review of surgical monitoring with auditory evoked potentials (AEPs) includes a detailed discussion of techniques used for recording brainstem auditory evoked potentials, direct eight-nerve potentials, and electrocochleograms. The normal waveform of these different potentials is discussed, and the typical patterns of abnormalities seen with different insults to the peripheral or central auditory pathways are presented. The mechanisms most probably responsible for changes in AEPs during surgical procedures are analyzed. A critical analysis is made of what represents a significant change in AEPs. Also considered is the predictive value of intrasurgical changes of AEPs. Finally, attempts are made to determine whether AEPs monitoring can assist the surgeon in the prevention of postsurgical complications.

Short latency vestibular evoked potentials in the chicken embryo

NASA Technical Reports Server (NTRS)

Jones, S. M.; Jones, T. A.

1996-01-01

Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies < 6.0 ms) were scored and latencies and amplitudes quantified. Vestibular response latencies were significantly longer (P < 0.01) and amplitudes significantly smaller (P < 0.001) than those observed in 2-week-old birds. Mean response threshold for anesthetized embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P < 0.03) than those observed in 2-week-old birds (-23.0dBre 1.0 g/ms). Latency/intensity functions (that is, slopes) were not significantly different between embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P < 0.001). We presume that these differences reflect the refinement of sensory function that occurs following 19 to 20 days of incubation. The recording of vestibular evoked potentials provides an objective, direct and noninvasive measure of peripheral vestibular function in the embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

Vestibular Evoked Myogenic Potential Produced by Bone-Conducted Stimuli: A Study on its Basics and Clinical Applications in Patients with Conductive and Sensorineural Hearing Loss and a Group with Vestibular Schawannoma.

PubMed

Mahdi, Parvane; Amali, Amin; Pourbakht, Akram; Karimi Yazdi, Alireza; Bassam, Ali

2013-06-01

Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in vestibular disorders. As it is evoked by loud sound stimulation, even mild conductive hearing loss may affect VEMP results. Bone-conducted (BC) stimulus is an alternative stimulation for evoking this response. This study aims to assess the characteristics of BC-VEMP in different groups of patients. We performed a cross sectional analysis on 20 healthy volunteers with normal pure-tone audiometry as a control group; and on a group of patients consisted of 20 participants with conductive hearing loss, five with bilateral sensorineural hearing loss and four with vestibular schawannoma. AC and BC-VEMP were performed in all participants. In control group the VEMP responses to both kinds of stimuli had an acceptable morphology and consisted of p13 and n23 waves. Latency value of these main components in each type of stimulus was not significantly different (P>0.05). However, the mean amplitude was larger in BC modality than AC stimulation (P=0.025). In the group with conductive hearing loss, the VEMP response was absent in fifteen (46.87%) of the 32 ears using the AC method, whereas all (100%) displayed positive elicitability of VEMP by BC method. Normal VEMP responses in both stimuli were evoked in all patients with sensorineural hearing loss. In patients with unilateral vestibular schwannomas (VS), 2 (50.00%) had neither AC-VEMP nor BC-VEMP. Auditory stimuli delivered by bone conduction can evoke VEMP response. These responses are of vestibular origin and can be used in vestibular evaluation of patients with conductive hearing loss.

Vestibular Evoked Myogenic Potential Produced by Bone-Conducted Stimuli: A Study on its Basics and Clinical Applications in Patients with Conductive and Sensorineural Hearing Loss and a Group with Vestibular Schawannoma

PubMed Central

Mahdi, Parvane; Amali, Amin; Pourbakht, Akram; Karimi Yazdi, Alireza; Bassam, Ali

2013-01-01

Introduction: Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in vestibular disorders. As it is evoked by loud sound stimulation, even mild conductive hearing loss may affect VEMP results. Bone-conducted (BC) stimulus is an alternative stimulation for evoking this response. This study aims to assess the characteristics of BC-VEMP in different groups of patients. Materials and Methods: We performed a cross sectional analysis on 20 healthy volunteers with normal pure-tone audiometry as a control group; and on a group of patients consisted of 20 participants with conductive hearing loss, five with bilateral sensorineural hearing loss and four with vestibular schawannoma. AC and BC-VEMP were performed in all participants. Results: In control group the VEMP responses to both kinds of stimuli had an acceptable morphology and consisted of p13 and n23 waves. Latency value of these main components in each type of stimulus was not significantly different (P>0.05). However, the mean amplitude was larger in BC modality than AC stimulation (P=0.025). In the group with conductive hearing loss, the VEMP response was absent in fifteen (46.87%) of the 32 ears using the AC method, whereas all (100%) displayed positive elicitability of VEMP by BC method. Normal VEMP responses in both stimuli were evoked in all patients with sensorineural hearing loss. In patients with unilateral vestibular schwannomas (VS), 2 (50.00%) had neither AC-VEMP nor BC-VEMP. Conclusion: Auditory stimuli delivered by bone conduction can evoke VEMP response. These responses are of vestibular origin and can be used in vestibular evaluation of patients with conductive hearing loss. PMID:24303434

Rhesus macaque model of chronic opiate dependence and neuro-AIDS: longitudinal assessment of auditory brainstem responses and visual evoked potentials

PubMed Central

Riazi, Mariam; Marcario, Joanne K; Samson, Frank K.; Kenjale, Himanshu; Adany, Istvan; Staggs, Vincent; Ledford, Emily; Marquis, Janet; Narayan, Opendra; Cheney, Paul D.

2013-01-01

Our work characterizes the effects of opiate (morphine) dependence on auditory brainstem and visual evoked responses in a rhesus macaque model of neuro-AIDS utilizing a chronic continuous drug delivery paradigm. The goal of this study was to clarify whether morphine is protective, or if it exacerbates simian immunodeficiency virus (SIV) related systemic and neurological disease. Our model employs a macrophage tropic CD4/CCR5 co-receptor virus, SIVmac239 (R71/E17), which crosses the blood brain barrier shortly after inoculation and closely mimics the natural disease course of human immunodeficiency virus (HIV) infection. The cohort was divided into 3 groups: morphine only, SIV only, and SIV + morphine. Evoked potential (EP) abnormalities in sub-clinically infected macaques were evident as early as eight weeks post-inoculation. Prolongations in EP latencies were observed in SIV-infected macaques across all modalities. Animals with the highest CSF viral loads and clinical disease showed more abnormalities than those with sub-clinical disease, confirming our previous work (Raymond et al, 1998, 1999, 2000). Although some differences were observed in auditory and visual evoked potentials in morphine treated compared to untreated SIV-infected animals, the effects were relatively small and not consistent across evoked potential type. However, morphine treated animals with subclinical disease had a clear tendency toward higher virus loads in peripheral and CNS tissues (Marcario et al., 2008) suggesting that if had been possible to follow all animals to end-stage disease, a clearer pattern of evoked potential abnormality might have emerged. PMID:19283490

Altered Automatic Face Processing in Individuals with High-Functioning Autism Spectrum Disorders: Evidence from Visual Evoked Potentials

ERIC Educational Resources Information Center

Fujita, Takako; Kamio, Yoko; Yamasaki, Takao; Yasumoto, Sawa; Hirose, Shinichi; Tobimatsu, Shozo

2013-01-01

Individuals with autism spectrum disorders (ASDs) have different automatic responses to faces than typically developing (TD) individuals. We recorded visual evoked potentials (VEPs) in 10 individuals with high-functioning ASD (HFASD) and 10 TD individuals. Visual stimuli consisted of upright and inverted faces (fearful and neutral) and objects…

Cortical evoked potentials to an auditory illusion: binaural beats.

PubMed

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2009-08-01

To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

Cortical Evoked Potentials to an Auditory Illusion: Binaural Beats

PubMed Central

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J.; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2009-01-01

Objective: To define brain activity corresponding to an auditory illusion of 3 and 6 Hz binaural beats in 250 Hz or 1,000 Hz base frequencies, and compare it to the sound onset response. Methods: Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000 Hz to one ear and 3 or 6 Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3 Hz and 6 Hz, in base frequencies of 250 Hz and 1000 Hz. Tones were 2,000 ms in duration and presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. Results: All stimuli evoked tone-onset P50, N100 and P200 components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P50 had significantly different sources than the beats-evoked oscillations; and N100 and P200 sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Conclusions: Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Significance: Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp. PMID:19616993

Auditory and visual P300 evoked potentials do not predict response to valproate treatment of aggression in patients with borderline and antisocial personality disorders.

PubMed

Reeves, Roy R; Struve, Frederick A; Patrick, Gloria

2005-01-01

In this study of patients with borderline personality disorder (BPD) or antisocial personality disorder (ASPD) hospitalized because of aggressive behavior, auditory and visual P300 evoked potentials were obtained prior to treatment with valproate. Eight ASPD patients (8 males, 0 females) and 11 BPD patients (2 males, 9 females) showed improvement, while in 7 patients with ASPD (7 males, 0 females) and 10 patients with BPD (2 males, 8 females), aggression was not improved. Differences in auditory and visual P300 latencies and amplitudes were not significant for either diagnosis, or for both diagnoses combined. These findings suggest that auditory or visual P300 evoked potentials may not be useful for predicting response of aggressive behavior to valproate treatment in patients with BPD or ASPD.

Ionic mechanisms underlying the responses of off-center bipolar cells in the carp retina. II. Studies on responses evoked by transretinal current stimulation.

PubMed

Kaneko, A; Saito, T

1983-04-01

Transretinal current pulses flowing from the receptor side to the vitreous side of the retina cause transient release of transmitter from the photoreceptor terminals, and in off-center bipolar cells they evoke transient depolarizations with a brief (less than 1 ms) synaptic delay. Since it is known that the presence of Na+ in the external medium is not essential for this type of transmitter release, we used this procedure to examine the role of [Na+]o in the generation of light-evoked responses (hyperpolarizing to spot illumination in the receptive field center and depolarizing to an annulus in the surround) of this type of bipolar cell. When the cell membrane was steadily depolarized by current injection through the recording microelectrode, the depolarizing response evoked by the transretinal current pulses decreased in amplitude and reversed its polarity at above +45 mV. Conversely, the response amplitude increased when the cell was steadily hyperpolarized. The reversal potential seems to be lowered in low [Na+]o (28 mM). Removal of Na+ from the superfusate hyperpolarized the cell and both the light-evoked and current-evoked responses disappeared. From these observations, it is hypothesized that the hyperpolarizing center response of the off-center bipolar cells is a result of removal of sustained depolarization produced by sodium permeability increase.

Artifacts produced during electrical stimulation of the vestibular nerve in cats. [autonomic nervous system components of motion sickness

NASA Technical Reports Server (NTRS)

Tang, P. C.

1973-01-01

Evidence is presented to indicate that evoked potentials in the recurrent laryngeal, the cervical sympathetic, and the phrenic nerve, commonly reported as being elicited by vestibular nerve stimulation, may be due to stimulation of structures other than the vestibular nerve. Experiments carried out in decerebrated cats indicated that stimulation of the petrous bone and not that of the vestibular nerve is responsible for the genesis of evoked potentials in the recurrent laryngeal and the cervical sympathetic nerves. The phrenic response to electrical stimulation applied through bipolar straight electrodes appears to be the result of stimulation of the facial nerve in the facial canal by current spread along the petrous bone, since stimulation of the suspended facial nerve evoked potentials only in the phrenic nerve and not in the recurrent laryngeal nerve. These findings indicate that autonomic components of motion sickness represent the secondary reactions and not the primary responses to vestibular stimulation.

Contact Heat Evoked Potentials (CHEPs) in Patients with Mild-Moderate Alzheimer's Disease and Matched Control--A Pilot Study.

PubMed

Jensen-Dahm, Christina; Madsen, Caspar Skau; Waldemar, Gunhild; Ballegaard, Martin; Hejl, Anne-Mette; Johnsen, Birger; Jensen, Troels Staehelin

2016-04-01

Clinical studies have found that patients with Alzheimer's disease report pain of less intensity and with a lower affective response, which has been thought to be due to altered pain processing. The authors wished to examine the cerebral processing of non-painful and painful stimuli using somatosensory evoked potentials and contact heat evoked potentials in patients with Alzheimer's disease and in healthy elderly controls. Case-control study Twenty outpatients with mild-moderate Alzheimer's disease and in 17 age- and gender-matched healthy controls were included Contact heat evoked potentials and somatosensory evoked potentials were recorded in all subjects. Furthermore, warmth detection threshold and heat pain threshold were assessed. Patients and controls also rated quality and intensity of the stimuli. The authors found no difference on contact heat evoked potential amplitude (P = 0.59) or latency of N2 or P2 wave (P = 0.62 and P = 0.75, respectively) between patients and controls. In addition, there was no difference in regard to pain intensity scores or pain quality. The patients and controls had similar warmth detection threshold and heat pain threshold. Somatosensory evoked potentials, amplitude, and latency were within normal range and similar for the two groups. The findings suggest that the processing of non-painful and painful stimuli is preserved in patients with mild to moderate Alzheimer's disease. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

High frequency bone conduction auditory evoked potentials in the guinea pig: Assessing cochlear injury after ossicular chain manipulation.

PubMed

Bergin, M J; Bird, P A; Vlajkovic, S M; Thorne, P R

2015-12-01

Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous diffuse near-infrared imaging of hemodynamic and oxygenation changes and electroencephalographic measurements of neuronal activity in the human brain

NASA Astrophysics Data System (ADS)

Noponen, Tommi; Kicic, Dubravko; Kotilahti, Kalle; Kajava, Timo; Kahkonen, Seppo; Nissila, Ilkka; Merilainen, Pekka; Katila, Toivo

2005-04-01

Visually evoked hemodynamic responses and potentials were simultaneously measured using a 16-channel optical imaging instrument and a 60-channel electroencephalography instrument during normo-, hypo- and hypercapnia from three subjects. Flashing and pattern-reversed checkerboard stimuli were used. The study protocol included two counterbalanced measurements during both normo- and hypocapnia and normo- and hypercapnia. Hypocapnia was produced by controlled hyperventilation and hypercapnia by breathing carbon dioxide enriched air. Near-infrared imaging was also used to monitor the concentration changes of oxy- and deoxyhaemoglobin due to hypo- and hypercapnia. Hemodynamic responses and evoked potentials were successfully detected for each subject above the visual cortex. The latencies of the hemodynamic responses during hypocapnia were shorter whereas during hypercapnia they were longer when compared to the latencies during normocapnia. Hypocapnia tended to decrease the latencies of visually evoked potentials compared to those during normocapnia while hypercapnia did not show any consistent effect to the potentials. The developed measurement setup and the study protocol provide the opportunity to investigate the neurovascular coupling and the links between the baseline level of blood flow, electrical activity and hemodynamic responses in the human brain.

Effects of single cycle binaural beat duration on auditory evoked potentials.

PubMed

Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan

2014-01-01

Binaural beat (BB) illusions are experienced as continuous central pulsations when two sounds with slightly different frequencies are delivered to each ear. It has been shown that steady-state auditory evoked potentials (AEPs) to BBs can be captured and investigated. The authors recently developed a new method of evoking transient AEPs to binaural beats using frequency modulated stimuli. This methodology was able to create single BBs in predetermined intervals with varying carrier frequencies. This study examines the effects of the BB duration and the frequency modulating component of the stimulus on the binaural beats and their evoked potentials. Normal hearing subjects were tested with a set of four durations (25, 50, 100, and 200 ms) with two stimulation configurations, binaural dichotic (binaural beats) and diotic (frequency modulation). The results obtained from the study showed that out of the given durations, the 100 ms beat, was capable of evoking the largest amplitude responses. The frequency modulation effect showed a decrease in peak amplitudes with increasing beat duration until their complete disappearance at 200 ms. Even though, at 200 ms, the frequency modulation effects were not present, the binaural beats were still perceived and captured as evoked potentials.

[Effect of acoustic stimulus intensity on air-conducted sound elicited ocular vestibular-evoked myogenic potential and cervical vestibular-evoked myogenic potential].

PubMed

Zhang, Rui; Xu, Min; Zhang, Qing; Yang, Yin-Tong; Chen, Yanfei

2014-06-01

To observe the effect of acoustic stimulus intensity on air-conducted sound elicited ocular vestibular- evoked myogenic potential (oVEMP) and cervical vestibular-evoked myogenic potential (cVEMP) in normal young Chinese subjects. Thirty-five normal subjects aged 4-40 years (20.80∓8.89 years), including 16 males and 19 females, were recruited for conventional oVEMP and cVEMP examinations. The responses obtained from each side using 500 Hz tone bursts were divided into 6 groups according to different sound intensities (100, 95, 90, 85, 80 and 75dB nHL). The response rate and normal parameters of each stimulus intensity group were calculated. As the acoustic stimulus intensity decreased, the oVEMP response rate decreased from 100% in both 100 dB nHL and 95dB nHL groups to 97.14% (90 dB nHL), 54.29% (85 dB nHL), 14.29% (80 dB nHL), and 2.86% (75 dB nHL), and the response rate of cVEMP, 100% in both 100 dB nHL and 95dB nHL groups, was lowered to 97.14% (90 dB nHL), 84.29% (85 dB nHL), 38.57% (80 dB nHL) and 8.57% (75 dB nHL). The response rate and the parameters were comparable between 100 and 95 dB nHL groups. As the acoustic stimulus intensity decreases, both oVEMP and cVEMP show decreased response rate and amplitude. For Chinese subjects under 40 years of age, we recommend 95dB nHL as the maximum initial stimulus intensity in VEMPs test.

Substance P analogues potentiate the pressor response to microinjection of L-glutamate into laminas I and II of the cat dorsal horn.

PubMed

Beyaert, C A; Hill, J M; Kaufman, M P

1997-06-06

Microinjection of a substance P analogue (1 mM; 7 or 10 nl) into laminae I and II of the L7 dorsal horn of decerebrate cats significantly potentiated (P < 0.05) the increase in arterial pressure evoked by microinjection of L-glutamate (109 mM; 7 or 10 nl) into these spinal sites. Microinjection of the substance P analogues (i.e., GR73638 and [Sar9,Met(O2)11]-substance P) which were selective NK-1 receptor agonists, had no impact on the cardioacceleration evoked by microinjection of L-glutamate (P > 0.05). In addition, microinjection of these analogues had no effect on the modest and non-significant increase in phrenic nerve discharge evoked by L-glutamate. We conclude that stimulation of NK-1 receptors in the superficial laminae of the dorsal horn potentiates the pressor responses to microinjection of L-glutamate.

Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B4-negative Medium-sized Trigeminal Ganglion Neurons.

PubMed

Sato, Masaki; Ogura, Kazuhiro; Kimura, Maki; Nishi, Koichi; Ando, Masayuki; Tazaki, Masakazu; Shibukawa, Yoshiyuki

2018-06-01

Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X 3 ), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B 4 -negative medium-sized neurons. Action potentials in these isolectin B 4 -negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X 3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X 3 receptors induced an action potential in the Aδ neurons, underlying a sensory generation mechanism of dentinal pain. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Direct sensorimotor corticospinal modulation of dorsal horn neuronal C-fiber responses in the rat.

PubMed

Rojas-Piloni, Gerardo; Martínez-Lorenzana, Guadalupe; Condés-Lara, Miguel; Rodríguez-Jiménez, Javier

2010-09-10

Clinically, the stimulation of motor cortical areas has been used to alleviate certain pain conditions. However, the attempts to understand the mechanisms of cortical nociceptive modulation at the spinal cord level have yielded controversial results. The objectives of the present work were to: 1) determine the effects of activating and suppressing the activity of sensorimotor cortical neurons on the nociceptive electrophysiological responses of the segmental C-fibers, and 2) evaluate the contribution of direct and indirect corticospinal projections in segmental nociceptive modulation. By means of a bipolar matrix of stimulation electrodes we mapped the stimulation of cortical areas that modulate C-fiber evoked field potentials in the dorsal horn. In addition, suppressing the cortical activity by means of cortical spreading depression, we observed that the C-fiber evoked field potentials in the dorsal horn are facilitated when cortical activity is suppressed specifically in sensorimotor cortex. Moreover, the C-fiber evoked field potentials were inhibited during spontaneous activation of cortical projecting neurons. Furthermore, after a lesion of the pyramidal tract contralateral to the spinal cord recording sites, the cortical action was suppressed. Our results show that corticospinal tract fibers arising from the sensorimotor cortex modulate directly the nociceptive C-fiber evoked responses of the dorsal horn. 2010. Published by Elsevier B.V.

Median and ulnar muscle and sensory evoked potentials.

PubMed

Felsenthal, G

1978-08-01

The medical literature was reviewed to find suggested clinical applications of the study of the amplitude of evoked muscle action potentials (MAP) and sensory action potentials (SAP). In addition, the literature was reviewed to ascertain the normal amplitude and duration of the evoked MAP and SAP as well as the factors affecting the amplitude: age, sex, temperature, ischemia. The present study determined the normal amplitude and duration of the median and ulnar MAP and SAP in fifty normal subjects. The amplitude of evoked muscle or sensory action potentials depends on multiple factors. Increased skin resistance, capacitance, and impedance at the surface of the recording electrode diminishes the amplitude. Similarly, increased distance from the source of the action potential diminishes its amplitude. Increased interelectrode distance increases the amplitude of the bipolarly recorded sensory action potential until a certain interelectrode distance is exceeded and the diphasic response becomes tri- or tetraphasic. Artifact or poor technique may reduce the potential difference between the recording electrodes or obscure the late positive phase of the action potential and thus diminish the peak to peak amplitude measurement. Intraindividual comparison indicated a marked difference of amplitude in opposite hands. The range of the MAP of the abductor pollicis brevis in one hand was 40.0--100% of the response in the opposite hand. For the abductor digiti minimi, the MAP was 58.5--100% of the response of the opposite hand. The median and ulnar SAP was between 50--100% of the opposite SAP. Consequent to these findings the effect of hand dominance on the amplitude of median and ulnar evoked muscle and sensory action potentials was studied in 41 right handed volunteers. The amplitudes of the median muscle action potential (p less than 0.02) and the median and ulnar sensory action potentials (p less than 0.001) were significantly less in the dominant hand. There was no significant difference between the ulnar muscle action potentials or for the median and ulnar distal motor and sensory latencies in the right and left hands of this group of volunteers.

Evoked potentials are useful for diagnosis of neuromyelitis optica spectrum disorder.

PubMed

Ohnari, Keiko; Okada, Kazumasa; Takahashi, Toshiyuki; Mafune, Kosuke; Adachi, Hiroaki

2016-05-15

Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

The steady-state visual evoked potential in vision research: A review

PubMed Central

Norcia, Anthony M.; Appelbaum, L. Gregory; Ales, Justin M.; Cottereau, Benoit R.; Rossion, Bruno

2015-01-01

Periodic visual stimulation and analysis of the resulting steady-state visual evoked potentials were first introduced over 80 years ago as a means to study visual sensation and perception. From the first single-channel recording of responses to modulated light to the present use of sophisticated digital displays composed of complex visual stimuli and high-density recording arrays, steady-state methods have been applied in a broad range of scientific and applied settings.The purpose of this article is to describe the fundamental stimulation paradigms for steady-state visual evoked potentials and to illustrate these principles through research findings across a range of applications in vision science. PMID:26024451

Interhemispheric Asymmetries in Visual Evoked Potential Amplitude

DTIC Science & Technology

1980-06-12

Layne, 1965) and of patients with Korsakoff’s syndrome (Malerstein and Callaway, 1969) . In the schizophrenics, the high variability is related to poor...communication. Malerstein, A. J., Callaway, E. Two-tone average evoked response in Korsakoff patients. J. Psychiatr. Res. 6: 253-260, 1969. Marsh, G

[The modified method registration of kinesthetic evoked potentials and its application for research of proprioceptive sensitivity disorders at spondylogenic cervical myelopathy].

PubMed

Gordeev, S A; Voronin, S G

2016-01-01

To analyze the efficacy of modified (passive radiocarpal articulation flexion/extension) and «standard» (passive radiocarpal articulation flexion) methods of kinesthetic evoked potentials for proprioceptive sensitivity assessment in healthy subjects and patients with spondylotic cervical myelopathy. The study included 14 healthy subjects (4 women and 10 men, mean age 54.1±10.5 years) and 8 patients (2 women and 6 men, mean age 55.8±10.9 years) with spondylotic cervical myelopathy. Muscle-joint sensation was examined during the clinical study. A modified method of kinesthetic evoked potentials was developed. This method differed from the "standard" one by the organization of a cycle including several passive movements,where each new movement differed from the preceding one by the direction. The modified method of kinesthetic evoked potentials ensures more reliable kinesthetic sensitivity assessment due to movement variability. Asignificant increaseof the latent periods of the early components of the response was found in patients compared to healthy subjects. The modified method of kinesthetic evoked potentials can be used for objective diagnosis of proprioceptive sensitivity disorders in patients with spondylotic cervical myelopathy.

Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system.

PubMed

Ellingson, Roger M; Oken, Barry

2010-01-01

Report contains the design overview and key performance measurements demonstrating the feasibility of generating and recording ambulatory visual stimulus evoked potentials using the previously reported custom Complementary and Alternative Medicine physiologic data collection and monitoring system, CAMAS. The methods used to generate visual stimuli on a PDA device and the design of an optical coupling device to convert the display to an electrical waveform which is recorded by the CAMAS base unit are presented. The optical sensor signal, synchronized to the visual stimulus emulates the brain's synchronized EEG signal input to CAMAS normally reviewed for the evoked potential response. Most importantly, the PDA also sends a marker message over the wireless Bluetooth connection to the CAMAS base unit synchronized to the visual stimulus which is the critical averaging reference component to obtain VEP results. Results show the variance in the latency of the wireless marker messaging link is consistent enough to support the generation and recording of visual evoked potentials. The averaged sensor waveforms at multiple CPU speeds are presented and demonstrate suitability of the Bluetooth interface for portable ambulatory visual evoked potential implementation on our CAMAS platform.

The Evoked Potential. An Experimental Method for Biomechanical Analysis of Brain and Spinal Injury

DTIC Science & Technology

1980-01-01

Newtons produced marked changes in blood pressure, heart rate and distraction of the cervical spinal column with minimal ligamentous disruption...pathologic distraction and pathologic flexion of the thoracic ver- tebral column (8). Cerebral responses were lost within two minutes aftex complete...However, the immediate flexion and distraction responses were not altered. These findings suggest that mechanical trauma alters the spinal cord evoked

Diagnostic specificity and familiality of early versus late evoked potentials to auditory paired stimuli across the schizophrenia-bipolar psychosis spectrum.

PubMed

Hamm, Jordan P; Ethridge, Lauren E; Boutros, Nashaat N; Keshavan, Matcheri S; Sweeney, John A; Pearlson, Godfrey D; Tamminga, Carol A; Clementz, Brett A

2014-04-01

Disrupted sensory processing is a core feature of psychotic disorders. Auditory paired stimuli (PS) evoke a complex neural response, but it is uncertain which aspects reflect shared and/or distinct liability for the most common severe psychoses, schizophrenia (SZ) and psychotic bipolar disorder (BDP). Evoked time-voltage/time-frequency domain responses quantified with EEG during a typical PS paradigm (S1-S2) were compared among proband groups (SZ [n = 232], BDP [181]), their relatives (SZrel [259], BDPrel [220]), and healthy participants (H [228]). Early S1-evoked responses were reduced in SZ and BDP, while later/S2 abnormalities showed SZ/SZrel and BDP/BDPrel specificity. Relatives' effects were absent/small despite significant familiality of the entire auditorineural response. This pattern suggests general and divergent biological pathways associated with psychosis, yet may reflect complications with conditioning solely on clinical phenomenology. Copyright © 2014 Society for Psychophysiological Research.

Neurophysiological detection of impending spinal cord injury during scoliosis surgery.

PubMed

Schwartz, Daniel M; Auerbach, Joshua D; Dormans, John P; Flynn, John; Drummond, Denis S; Bowe, J Andrew; Laufer, Samuel; Shah, Suken A; Bowen, J Richard; Pizzutillo, Peter D; Jones, Kristofer J; Drummond, Denis S

2007-11-01

Despite the many reports attesting to the efficacy of intraoperative somatosensory evoked potential monitoring in reducing the prevalence of iatrogenic spinal cord injury during corrective scoliosis surgery, these afferent neurophysiological signals can provide only indirect evidence of injury to the motor tracts since they monitor posterior column function. Early reports on the use of transcranial electric motor evoked potentials to monitor the corticospinal motor tracts directly suggested that the method holds great promise for improving detection of emerging spinal cord injury. We sought to compare the efficacy of these two methods of monitoring to detect impending iatrogenic neural injury during scoliosis surgery. We reviewed the intraoperative neurophysiological monitoring records of 1121 consecutive patients (834 female and 287 male) with adolescent idiopathic scoliosis (mean age, 13.9 years) treated between 2000 and 2004 at four pediatric spine centers. The same group of experienced surgical neurophysiologists monitored spinal cord function in all patients with use of a standardized multimodality technique with the patient under total intravenous anesthesia. A relevant neurophysiological change (an alert) was defined as a reduction in amplitude (unilateral or bilateral) of at least 50% for somatosensory evoked potentials and at least 65% for transcranial electric motor evoked potentials compared with baseline. Thirty-eight (3.4%) of the 1121 patients had recordings that met the criteria for a relevant signal change (i.e., an alert). Of those thirty-eight patients, seventeen showed suppression of the amplitude of transcranial electric motor evoked potentials in excess of 65% without any evidence of changes in somatosensory evoked potentials. In nine of the thirty-eight patients, the signal change was related to hypotension and was corrected with augmentation of the blood pressure. The remaining twenty-nine patients had an alert that was related directly to a surgical maneuver. Three alerts occurred following segmental vessel clamping, and the remaining twenty-six were related to posterior instrumentation and correction. Nine (35%) of these twenty-six patients with an instrumentation-related alert, or 0.8% of the cohort, awoke with a transient motor and/or sensory deficit. Seven of these nine patients presented solely with a motor deficit, which was detected by intraoperative monitoring of transcranial electric motor evoked potentials in all cases, and two patients had only sensory symptoms. Somatosensory evoked potential monitoring failed to identify a motor deficit in four of the seven patients with a confirmed motor deficit. Furthermore, when changes in somatosensory evoked potentials occurred, they lagged behind the changes in transcranial electric motor evoked potentials by an average of approximately five minutes. With an appropriate response to the alert, the motor or sensory deficit resolved in all nine patients within one to ninety days. This study underscores the advantage of monitoring the spinal cord motor tracts directly by recording transcranial electric motor evoked potentials in addition to somatosensory evoked potentials. Transcranial electric motor evoked potentials are exquisitely sensitive to altered spinal cord blood flow due to either hypotension or a vascular insult. Moreover, changes in transcranial electric motor evoked potentials are detected earlier than are changes in somatosensory evoked potentials, thereby facilitating more rapid identification of impending spinal cord injury.

Evoked Electrical and Cerebral Vascular Responses Following Sleep Deprivation

PubMed Central

Schei, Jennifer L.; Rector, David M.

2011-01-01

Neuronal activity elicits vascular dilation, delivering additional blood and metabolites to the activated region. With increasing neural activity, vessels stretch and may become less compliant. Most functional imaging studies assume that limits to vascular expansion are not normally reached except under pathological conditions, with the possibility that metabolism could outpace supply. However, we previously demonstrated that evoked hemodynamic responses were larger during quiet sleep when compared to both waking and REM sleep, suggesting that high basal activity during wake may elicit blunted evoked hemodynamic responses due to vascular expansion limits. We hypothesized that extended brain activity through sleep deprivation will further dilate blood vessels, and exacerbate the blunted evoked hemodynamic responses observed during wake, and dampen responses in subsequent sleep. We measured evoked electrical and hemodynamic responses from rats using auditory clicks (0.5 s, 10 Hz, 2–13 s random ISIs) for one hour following 2, 4, or 6 hours of sleep deprivation. Time-of-day matched controls were recorded continuously for 7 hours. Within quiet sleep periods following deprivation, ERP amplitude did not differ; however, the evoked vascular response was smaller with longer sleep deprivation periods. These results suggest that prolonged neural activity periods through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic sleep disturbances could push the vasculature to critical limits, leading to metabolic deficit and the potential for tissue trauma. PMID:21854966

Effect of mechanical tactile noise on amplitude of visual evoked potentials: multisensory stochastic resonance.

PubMed

Méndez-Balbuena, Ignacio; Huidobro, Nayeli; Silva, Mayte; Flores, Amira; Trenado, Carlos; Quintanar, Luis; Arias-Carrión, Oscar; Kristeva, Rumyana; Manjarrez, Elias

2015-10-01

The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. Copyright © 2015 the American Physiological Society.

Thermoreceptive innervation of human glabrous and hairy skin: a contact heat evoked potential analysis.

PubMed

Granovsky, Yelena; Matre, Dagfinn; Sokolik, Alexander; Lorenz, Jürgen; Casey, Kenneth L

2005-06-01

The human palm has a lower heat detection threshold and a higher heat pain threshold than hairy skin. Neurophysiological studies of monkeys suggest that glabrous skin has fewer low threshold heat nociceptors (AMH type 2) than hairy skin. Accordingly, we used a temperature-controlled contact heat evoked potential (CHEP) stimulator to excite selectively heat receptors with C fibers or Adelta-innervated AMH type 2 receptors in humans. On the dorsal hand, 51 degrees C stimulation produced painful pinprick sensations and 41 degrees C stimuli evoked warmth. On the glabrous thenar, 41 degrees C stimulation produced mild warmth and 51 degrees C evoked strong but painless heat sensations. We used CHEP responses to estimate the conduction velocities (CV) of peripheral fibers mediating these sensations. On hairy skin, 41 degrees C stimuli evoked an ultra-late potential (mean, SD; N wave latency: 455 (118) ms) mediated by C fibers (CV by regression analysis: 1.28 m/s, N=15) whereas 51 degrees C stimuli evoked a late potential (N latency: 267 (33) ms) mediated by Adelta afferents (CV by within-subject analysis: 12.9 m/s, N=6). In contrast, thenar responses to 41 and 51 degrees C were mediated by C fibers (average N wave latencies 485 (100) and 433 (73) ms, respectively; CVs 0.95-1.35 m/s by regression analysis, N=15; average CV=1.7 (0.41) m/s calculated from distal glabrous and proximal hairy skin stimulation, N=6). The exploratory range of the human and monkey palm is enhanced by the abundance of low threshold, C-innervated heat receptors and the paucity of low threshold AMH type 2 heat nociceptors.

Suppressive Effects of Resveratrol Treatment on The Intrinsic Evoked Excitability of CA1 Pyramidal Neurons

PubMed Central

Meftahi, Gholamhossein; Ghotbedin, Zohreh; Eslamizade, Mohammad Javad; Hosseinmardi, Narges; Janahmadi, Mahyar

2015-01-01

Objective Resveratrol, a phytoalexin, has a wide range of desirable biological actions. Despite a growing body of evidence indicating that resveratrol induces changes in neu- ronal function, little effort, if any, has been made to investigate the cellular effect of res- veratrol treatment on intrinsic neuronal properties. Materials and Methods This experimental study was performed to examine the acute effects of resveratrol (100 µM) on the intrinsic evoked responses of rat Cornu Ammonis (CA1) pyramidal neurons in brain slices, using whole cell patch clamp re- cording under current clamp conditions. Results Findings showed that resveratrol treatment caused dramatic changes in evoked responses of pyramidal neurons. Its treatment induced a significant (P<0.05) increase in the after hyperpolarization amplitude of the first evoked action potential. Resveratrol-treated cells displayed a significantly broader action potential (AP) when compared with either control or vehicle-treated groups. In addition, the mean instantaneous firing frequency between the first two action potentials was significantly lower in resveratrol-treated neurons. It also caused a significant reduction in the time to maximum decay of AP. The rheobase current and the utilization time were both significantly greater following resveratrol treatment. Neurons exhibited a significantly depolarized voltage threshold when exposed to resveratrol. Conclusion Results provide direct electrophysiological evidence for the inhibitory effects of resveratrol on pyramidal neurons, at least in part, by reducing the evoked neural activity. PMID:26464825

Auditory Evoked Potentials as a Function of Sleep Deprivation and Recovery Sleep

DTIC Science & Technology

1985-09-29

present research: They relate to the effects of: a) 48-hours of sleep deprivation on endogenous event related potentials (ERPs); b) circadian rhythms on...the study were: decreases in amplitude for N2, P3 and N2P3 across the reprivation period; a circadian rhythm was apparent for both ERP recordings and...of cortical evoked response potentials (ERPs)? 2) How do circadian rhythms affect ERPS under conditions of sleep deprivation? 3) How do different

Peripheral generators of the vestibular evoked potentials (VsEPs) in the chick.

PubMed

Weisleder, P; Jones, T A; Rubel, E W

1990-10-01

Electrophysiological activity in response to linear acceleration stimuli was recorded from young chickens by means of subcutaneous electrodes. This investigation had 2 purposes: (1) to establish the vestibular origin of the potentials; and (2) to investigate the contribution of each vestibular labyrinth to the response. The stimuli consisted of pulses of linear acceleration delivered by a mechanical vibrator (shaker). In the first set of experiments vestibular evoked potentials (VsEPs) were recorded prior to and 24 h after bilateral cochlea removal. In the second set of experiments responses were recorded before and after unilateral or bilateral intralabyrinthine injections of tetrodotoxin (TTX). Different groups of subjects were used for each experimental condition. The general morphology of the VsEPs was maintained after bilateral cochlea removal. Absolute latency of wave P2, the most prominent component of the response, was not significantly affected by the manipulation. Unilateral intralabyrinthine TTX injections consistently prolonged the latency and reduced the amplitude of wave P2. Following binaural TTX injections we were unable to elicit responses at the acceleration levels used in this study. The results from these experiments suggest that: (1) the activity recorded in response to linear acceleration stimuli is vestibular in origin; (2) when recorded from intact animals the evoked response is composed of activity from both vestibular systems; and (3) TTX consistently blocks the activity of the vestibular portion of the VIIIth cranial nerve.

Simultaneous detection of P300 and steady-state visually evoked potentials for hybrid brain-computer interface.

PubMed

Combaz, Adrien; Van Hulle, Marc M

2015-01-01

We study the feasibility of a hybrid Brain-Computer Interface (BCI) combining simultaneous visual oddball and Steady-State Visually Evoked Potential (SSVEP) paradigms, where both types of stimuli are superimposed on a computer screen. Potentially, such a combination could result in a system being able to operate faster than a purely P300-based BCI and encode more targets than a purely SSVEP-based BCI. We analyse the interactions between the brain responses of the two paradigms, and assess the possibility to detect simultaneously the brain activity evoked by both paradigms, in a series of 3 experiments where EEG data are analysed offline. Despite differences in the shape of the P300 response between pure oddball and hybrid condition, we observe that the classification accuracy of this P300 response is not affected by the SSVEP stimulation. We do not observe either any effect of the oddball stimulation on the power of the SSVEP response in the frequency of stimulation. Finally results from the last experiment show the possibility of detecting both types of brain responses simultaneously and suggest not only the feasibility of such hybrid BCI but also a gain over pure oddball- and pure SSVEP-based BCIs in terms of communication rate.

Pain-related somatosensory evoked potentials and functional brain magnetic resonance in the evaluation of neurologic recovery after cardiac arrest: a case study of three patients.

PubMed

Zanatta, Paolo; Messerotti Benvenuti, Simone; Baldanzi, Fabrizio; Bendini, Matteo; Saccavini, Marsilio; Tamari, Wadih; Palomba, Daniela; Bosco, Enrico

2012-03-31

This case series investigates whether painful electrical stimulation increases the early prognostic value of both somatosensory-evoked potentials and functional magnetic resonance imaging in comatose patients after cardiac arrest. Three single cases with hypoxic-ischemic encephalopathy were considered. A neurophysiological evaluation with an electroencephalogram and somatosensory-evoked potentials during increased electrical stimulation in both median nerves was performed within five days of cardiac arrest. Each patient also underwent a functional magnetic resonance imaging evaluation with the same neurophysiological protocol one month after cardiac arrest. One patient, who completely recovered, showed a middle latency component at a high intensity of stimulation and the activation of all brain areas involved in cerebral pain processing. One patient in a minimally conscious state only showed the cortical somatosensory response and the activation of the primary somatosensory cortex. The last patient, who was in a vegetative state, did not show primary somatosensory evoked potentials; only the activation of subcortical brain areas occurred. These preliminary findings suggest that the pain-related somatosensory evoked potentials performed to increase the prognosis of comatose patients after cardiac arrest are associated with regional brain activity showed by functional magnetic resonance imaging during median nerves electrical stimulation. More importantly, this cases report also suggests that somatosensory evoked potentials and functional magnetic resonance imaging during painful electrical stimulation may be sensitive and complementary methods to predict the neurological outcome in the acute phase of coma. Thus, pain-related somatosensory-evoked potentials may be a reliable and a cost-effective tool for planning the early diagnostic evaluation of comatose patients.

Testing the vestibular evoked myogenic potential (VEMP) to identify subclinical neurological alterations in different phases of human T-lymphotropic virus type 1 infection.

PubMed

Felipe, Lilian; Kingma, Herman; Lambertucci, José R; Carneiro-Proietti, Anna B; Gonçalves, Denise U

2013-04-01

The diagnosis of human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is based on clinical signs and the confirmation of HTLV-1 infection in the central nervous system. Electrophysiological tests may facilitate an earlier diagnosis of spinal cord involvement. Vestibular evoked myogenic potential (VEMP) testing evaluates the vestibulospinal tract, which is correlated with the motor tract; the target of damage by HAM/TSP. This study examines the subclinical neurological alterations related to HTLV-1 infection in individuals with asymptomatic HTLV-1 infections, possible HAM/TSP, and confirmed HAM/TSP. Vestibular evoked myogenic potential testing was performed at the beginning of the study and repeated every 6 months for 18 months. Ninety volunteers were selected for the study: 30 were HTLV-1 seronegative (the control group) and 60 were HTLV-1 seropositive (of these, 18 were asymptomatic, 25 had possible HAM/TSP, and 17 had confirmed HAM/TSP). The VEMP response was classified as normal or abnormal (latency prolongation or no response). A change in the VEMP response from normal to abnormal was the event of interest. To perform a survival analysis, the subjects with normal VEMP responses at the first assessment were selected. The results were analyzed blindly. Vestibular evoked myogenic potential was measured using short tone bursts as acoustic stimuli (1 kHz, 118 dBHL, a rise-fall of 1 millisecond, and a plateau of 2 milliseconds). The stimulation rate was 5 Hz, and the analysis time for each response was 60 milliseconds; each trial averaged 200 responses. The mean age of the subjects in the control group was 38 ± 11 years (median 35), and 13 (43%) were men. In the study group, the mean age was 51 ± 12 years (median 53), and 12 (20%) were men. An analysis of the survival curve indicated that the median time for a change in VEMP response from normal to abnormal was 18 months, which is in agreement with the slow progression of HTLV-1-associated neurologic disease. The survival analysis showed that the change in VEMP response was significantly different between the asymptomatic and HAM/TSP groups (p=.02). Vestibular evoked myogenic potential testing was useful for monitoring the development of HAM/TSP in HTLV-1-infected individuals. Copyright © 2013 Elsevier Inc. All rights reserved.

Investigation of Abnormal Left Temporal Functioning in Dyslexia through rCBF, Auditory Evoked Potentials, and Positron Emission Tomography.

ERIC Educational Resources Information Center

Wood, Frank; And Others

1991-01-01

Investigates the proposed left hemisphere dysfunction in dyslexia by reviewing four studies using regional cerebral blood flow (RCBF) and combined auditory evoked responses with positron emission tomography. Emphasizes methodological issues. Finds that dyslexics showed a positive correlation between Heschl's gyrus activation and phonemic…

Effects of musical training on the auditory cortex in children.

PubMed

Trainor, Laurel J; Shahin, Antoine; Roberts, Larry E

2003-11-01

Several studies of the effects of musical experience on sound representations in the auditory cortex are reviewed. Auditory evoked potentials are compared in response to pure tones, violin tones, and piano tones in adult musicians versus nonmusicians as well as in 4- to 5-year-old children who have either had or not had extensive musical experience. In addition, the effects of auditory frequency discrimination training in adult nonmusicians on auditory evoked potentials are examined. It was found that the P2-evoked response is larger in both adult and child musicians than in nonmusicians and that auditory training enhances this component in nonmusician adults. The results suggest that the P2 is particularly neuroplastic and that the effects of musical experience can be seen early in development. They also suggest that although the effects of musical training on cortical representations may be greater if training begins in childhood, the adult brain is also open to change. These results are discussed with respect to potential benefits of early musical training as well as potential benefits of musical experience in aging.

Premature infants display increased noxious-evoked neuronal activity in the brain compared to healthy age-matched term-born infants.

PubMed

Slater, Rebeccah; Fabrizi, Lorenzo; Worley, Alan; Meek, Judith; Boyd, Stewart; Fitzgerald, Maria

2010-08-15

This study demonstrates that infants who are born prematurely and who have experienced at least 40days of intensive or special care have increased brain neuronal responses to noxious stimuli compared to healthy newborns at the same postmenstrual age. We have measured evoked potentials generated by noxious clinically-essential heel lances in infants born at term (8 infants; born 37-40weeks) and in infants born prematurely (7 infants; born 24-32weeks) who had reached the same postmenstrual age (mean age at time of heel lance 39.2+/-1.2weeks). These noxious-evoked potentials are clearly distinguishable from shorter latency potentials evoked by non-noxious tactile sensory stimulation. While the shorter latency touch potentials are not dependent on the age of the infant at birth, the noxious-evoked potentials are significantly larger in prematurely-born infants. This enhancement is not associated with specific brain lesions but reflects a functional change in pain processing in the brain that is likely to underlie previously reported changes in pain sensitivity in older ex-preterm children. Our ability to quantify and measure experience-dependent changes in infant cortical pain processing will allow us to develop a more rational approach to pain management in neonatal intensive care. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Functional connectivity between right and left mesial temporal structures.

PubMed

Lacuey, Nuria; Zonjy, Bilal; Kahriman, Emine S; Kaffashi, Farhad; Miller, Jonathan; Lüders, Hans O

2015-09-01

The aim of this study is to investigate functional connectivity between right and left mesial temporal structures using cerebrocerebral evoked potentials. We studied seven patients with drug-resistant focal epilepsy who were explored with stereotactically implanted depth electrodes in bilateral hippocampi. In all patients cerebrocerebral evoked potentials evoked by stimulation of the fornix were evaluated as part of a research project assessing fornix stimulation for control of hippocampal seizures. Stimulation of the fornix elicited responses in the ipsilateral hippocampus in all patients with a mean latency of 4.6 ms (range 2-7 ms). Two patients (29 %) also had contralateral hippocampus responses with a mean latency of 7.5 ms (range 5-12 ms) and without involvement of the contralateral temporal neocortex or amygdala. This study confirms the existence of connections between bilateral mesial temporal structures in some patients and explains seizure discharge spreading between homotopic mesial temporal structures without neocortical involvement.

Cortical Auditory Evoked Potentials with Simple (Tone Burst) and Complex (Speech) Stimuli in Children with Cochlear Implant

PubMed Central

Martins, Kelly Vasconcelos Chaves; Gil, Daniela

2017-01-01

Introduction  The registry of the component P1 of the cortical auditory evoked potential has been widely used to analyze the behavior of auditory pathways in response to cochlear implant stimulation. Objective  To determine the influence of aural rehabilitation in the parameters of latency and amplitude of the P1 cortical auditory evoked potential component elicited by simple auditory stimuli (tone burst) and complex stimuli (speech) in children with cochlear implants. Method  The study included six individuals of both genders aged 5 to 10 years old who have been cochlear implant users for at least 12 months, and who attended auditory rehabilitation with an aural rehabilitation therapy approach. Participants were submitted to research of the cortical auditory evoked potential at the beginning of the study and after 3 months of aural rehabilitation. To elicit the responses, simple stimuli (tone burst) and complex stimuli (speech) were used and presented in free field at 70 dB HL. The results were statistically analyzed, and both evaluations were compared. Results  There was no significant difference between the type of eliciting stimulus of the cortical auditory evoked potential for the latency and the amplitude of P1. There was a statistically significant difference in the P1 latency between the evaluations for both stimuli, with reduction of the latency in the second evaluation after 3 months of auditory rehabilitation. There was no statistically significant difference regarding the amplitude of P1 under the two types of stimuli or in the two evaluations. Conclusion  A decrease in latency of the P1 component elicited by both simple and complex stimuli was observed within a three-month interval in children with cochlear implant undergoing aural rehabilitation. PMID:29018498

Event-related potentials to visual, auditory, and bimodal (combined auditory-visual) stimuli.

PubMed

Isoğlu-Alkaç, Ummühan; Kedzior, Karina; Keskindemirci, Gonca; Ermutlu, Numan; Karamursel, Sacit

2007-02-01

The purpose of this study was to investigate the response properties of event related potentials to unimodal and bimodal stimulations. The amplitudes of N1 and P2 were larger during bimodal evoked potentials (BEPs) than auditory evoked potentials (AEPs) in the anterior sites and the amplitudes of P1 were larger during BEPs than VEPs especially at the parieto-occipital locations. Responses to bimodal stimulation had longer latencies than responses to unimodal stimulation. The N1 and P2 components were larger in amplitude and longer in latency during the bimodal paradigm and predominantly occurred at the anterior sites. Therefore, the current bimodal paradigm can be used to investigate the involvement and location of specific neural generators that contribute to higher processing of sensory information. Moreover, this paradigm may be a useful tool to investigate the level of sensory dysfunctions in clinical samples.

Natural sleep modifies the rat electroretinogram.

PubMed Central

Galambos, R; Juhász, G; Kékesi, A K; Nyitrai, G; Szilágyi, N

1994-01-01

We show here electroretinograms (ERGs) recorded from freely moving rats during sleep and wakefulness. Bilateral ERGs were evoked by flashes delivered through a light-emitting diode implanted under the skin above one eye and recorded through electrodes inside each orbit near the optic nerve. Additional electrodes over each visual cortex monitored the brain waves and collected flash-evoked cortical potentials to compare with the ERGs. Connections to the stimulating and recording instruments through a plug on the head made data collection possible at any time without physically disturbing the animal. The three major findings are (i) the ERG amplitude during slow-wave sleep can be 2 or more times that of the waking response; (ii) the ERG patterns in slow-wave and REM sleep are different; and (iii) the sleep-related ERG changes closely mimic those taking place at the same time in the responses evoked from the visual cortex. We conclude that the mechanisms that alter the visual cortical-evoked responses during sleep operate also and similarly at the retinal level. PMID:8197199

Extinction of cue-evoked drug-seeking relies on degrading hierarchical instrumental expectancies

PubMed Central

Hogarth, Lee; Retzler, Chris; Munafò, Marcus R.; Tran, Dominic M.D.; Troisi, Joseph R.; Rose, Abigail K.; Jones, Andrew; Field, Matt

2014-01-01

There has long been need for a behavioural intervention that attenuates cue-evoked drug-seeking, but the optimal method remains obscure. To address this, we report three approaches to extinguish cue-evoked drug-seeking measured in a Pavlovian to instrumental transfer design, in non-treatment seeking adult smokers and alcohol drinkers. The results showed that the ability of a drug stimulus to transfer control over a separately trained drug-seeking response was not affected by the stimulus undergoing Pavlovian extinction training in experiment 1, but was abolished by the stimulus undergoing discriminative extinction training in experiment 2, and was abolished by explicit verbal instructions stating that the stimulus did not signal a more effective response-drug contingency in experiment 3. These data suggest that cue-evoked drug-seeking is mediated by a propositional hierarchical instrumental expectancy that the drug-seeking response is more likely to be rewarded in that stimulus. Methods which degraded this hierarchical expectancy were effective in the laboratory, and so may have therapeutic potential. PMID:25011113

The N-methyl-D-aspartate-evoked cytoplasmic calcium increase in adult rat dorsal root ganglion neuronal somata was potentiated by substance P pretreatment in a protein kinase C-dependent manner.

PubMed

Castillo, C; Norcini, M; Baquero-Buitrago, J; Levacic, D; Medina, R; Montoya-Gacharna, J V; Blanck, T J J; Dubois, M; Recio-Pinto, E

2011-03-17

The involvement of substance P (SP) in neuronal sensitization through the activation of the neurokinin-1-receptor (NK1r) in postsynaptic dorsal horn neurons has been well established. In contrast, the role of SP and NK1r in primary sensory dorsal root ganglion (DRG) neurons, in particular in the soma, is not well understood. In this study, we evaluated whether SP modulated the NMDA-evoked transient increase in cytoplasmic Ca2+ ([Ca2+]cyt) in the soma of dissociated adult DRG neurons. Cultures were treated with nerve growth factor (NGF), prostaglandin E2 (PGE2) or both NGF+PGE2. Treatment with NGF+PGE2 increased the percentage of N-methyl-D-aspartate (NMDA) responsive neurons. There was no correlation between the percentage of NMDA responsive neurons and the level of expression of the NR1 and NR2B subunits of the NMDA receptor or of the NK1r. Pretreatment with SP did not alter the percentage of NMDA responsive neurons; while it potentiated the NMDA-evoked [Ca2+]cyt transient by increasing its magnitude and by prolonging the period during which small- and some medium-sized neurons remained NMDA responsive. The SP-mediated potentiation was blocked by the SP-antagonist ([D-Pro4, D-Trp7,9]-SP (4-11)) and by the protein kinase C (PKC) blocker bisindolylmaleimide I (BIM); and correlated with the phosphorylation of PKCε. The Nk1r agonist [Sar9, Met(O2)11]-SP (SarMet-SP) also potentiated the NMDA-evoked [Ca2+]cyt transient. Exposure to SP or SarMet-SP produced a rapid increase in the labeling of phosphorylated-PKCε. In none of the conditions we detected phosphorylation of the NR2B subunit at Ser-1303. Phosphorylation of the NR2B subunit at Tyr1472 was enhanced to a similar extent in cells exposed to NMDA, SP or NMDA+SP, and that enhancement was blocked by BIM. Our findings suggest that NGF and PGE2 may contribute to the injury-evoked sensitization of DRG neurons in part by enhancing their NMDA-evoked [Ca2+]cyt transient in all sized DRG neurons; and that SP may further contribute to the DRG sensitization by enhancing and prolonging the NMDA-evoked increase in [Ca2+]cyt in small- and medium-sized DRG neurons. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Quantification of the proportion of motor neurons recruited by transcranial electrical stimulation during intraoperative motor evoked potential monitoring.

PubMed

Tsutsui, Shunji; Yamada, Hiroshi; Hashizume, Hiroshi; Minamide, Akihito; Nakagawa, Yukihiro; Iwasaki, Hiroshi; Yoshida, Munehito

2013-12-01

Transcranial motor evoked potentials (TcMEPs) are widely used to monitor motor function during spinal surgery. However, they are much smaller and more variable in amplitude than responses evoked by maximal peripheral nerve stimulation, suggesting that a limited number of spinal motor neurons to the target muscle are excited by transcranial stimulation. The aim of this study was to quantify the proportion of motor neurons recruited during TcMEP monitoring under general anesthesia. In twenty patients who underwent thoracic and/or lumbar spinal surgery with TcMEP monitoring, the triple stimulation technique (TST) was applied to the unilateral upper arm intraoperatively. Total intravenous anesthesia was employed. Trains of four stimuli were delivered with maximal intensity and an inter-pulse interval of 1.5 ms. TST responses were recorded from the abductor digiti minimi muscle, and the negative peak amplitude and area were measured and compared between the TST test (two collisions between transcranial and proximal and distal peripheral stimulation) and control response (two collisions between two proximal and one distal peripheral stimulation). The highest degree of superimposition of the TST test and control responses was chosen from several trials per patient. The average ratios (test:control) were 17.1 % (range 1.8-38 %) for the amplitudes and 21.6 % (range 2.9-40 %) for the areas. The activity of approximately 80 % of the motor units to the target muscle cannot be detected by TcMEP monitoring. Therefore, changes in evoked potentials must be interpreted cautiously when assessing segmental motor function with TcMEP monitoring.

Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system functions after developmental exposure to ethanol vapors.

PubMed

Boyes, William K; Degn, Laura L; Martin, Sheppard A; Lyke, Danielle F; Hamm, Charles W; Herr, David W

2014-01-01

Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation of ethanol vapors by themselves, and also as a baseline for evaluating the risks of ethanol combined with a complex mixture of hydrocarbon vapors. Because sensory dysfunction has been reported after developmental exposure to ethanol, we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Pregnant Long-Evans rats were exposed to target concentrations 0, 5000, 10,000, or 21,000 ppm ethanol vapors for 6.5h/day over GD9-GD20. Sensory evaluations of male offspring began between PND106 and PND128. Peripheral nerve function (compound action potentials, nerve conduction velocity (NCV)), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEPs), VEP contrast sensitivity, and electroretinograms recorded from dark-adapted (scotopic), light-adapted (photopic) flashes, and UV flicker and green flicker. No consistent concentration-related changes were observed for any of the physiological measures. The results show that gestational exposure to ethanol vapor did not result in detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults. Published by Elsevier Inc.

Electrophysiology and Innervation of the Photosensitive Epistellar Body in the Lesser Octopus Eledone cirrhosa.

PubMed

Cobb, C S; Williamson, R

1998-08-01

The innervation and responses to light of the cephalopod epistellar body were investigated in preparations isolated from the stellate ganglia of the lesser or northern octopus, Eledone cirrhosa. Extracellular generator potentials in response to flashes of light were recorded from these photosensitive vesicles, with the amplitude of the response being found to be dependent upon the intensity of the flash and the level of ambient illumination. Intracellular recordings from photoreceptor cells of the epistellar body showed that they had resting potentials of about -49 +/- 7 mV (mean +/- SD, n = 43) and were depolarized by flashes of white, but not red (>650 nm) light. The evoked depolarization consisted of a transient component, followed by a steady plateau in which the amplitude of the depolarization was well correlated with the log of the stimulus intensity. The evoked depolarizations induced action potentials in the photoreceptor cells, with the frequency of firing being well correlated with the stimulus intensity. The morphologies of individual photoreceptor cells were visualized by intracellular injections of the fluorescent dye Lucifer yellow, and the path of the epistellar nerve across the stellate ganglion, into the pallial nerve, toward the brain was traced using the lipophilic dye Di-I. This pathway was confirmed physiologically by recording light-evoked responses from the cut end of the pallial nerve.

Differentially Variable Component Analysis (dVCA): Identifying Multiple Evoked Components using Trial-to-Trial Variability

NASA Technical Reports Server (NTRS)

Knuth, Kevin H.; Shah, Ankoor S.; Truccolo, Wilson; Ding, Ming-Zhou; Bressler, Steven L.; Schroeder, Charles E.

2003-01-01

Electric potentials and magnetic fields generated by ensembles of synchronously active neurons in response to external stimuli provide information essential to understanding the processes underlying cognitive and sensorimotor activity. Interpreting recordings of these potentials and fields is difficult as each detector records signals simultaneously generated by various regions throughout the brain. We introduce the differentially Variable Component Analysis (dVCA) algorithm, which relies on trial-to-trial variability in response amplitude and latency to identify multiple components. Using simulations we evaluate the importance of response variability to component identification, the robustness of dVCA to noise, and its ability to characterize single-trial data. Finally, we evaluate the technique using visually evoked field potentials recorded at incremental depths across the layers of cortical area VI, in an awake, behaving macaque monkey.

Human lateral geniculate nucleus and visual cortex respond to screen flicker.

PubMed

Krolak-Salmon, Pierre; Hénaff, Marie-Anne; Tallon-Baudry, Catherine; Yvert, Blaise; Guénot, Marc; Vighetto, Alain; Mauguière, François; Bertrand, Olivier

2003-01-01

The first electrophysiological study of the human lateral geniculate nucleus (LGN), optic radiation, striate, and extrastriate visual areas is presented in the context of presurgical evaluation of three epileptic patients (Patients 1, 2, and 3). Visual-evoked potentials to pattern reversal and face presentation were recorded with depth intracranial electrodes implanted stereotactically. For Patient 1, electrode anatomical registration, structural magnetic resonance imaging, and electrophysiological responses confirmed the location of two contacts in the geniculate body and one in the optic radiation. The first responses peaked approximately 40 milliseconds in the LGN in Patient 1 and 60 milliseconds in the V1/V2 complex in Patients 2 and 3. Moreover, steady state visual-evoked potentials evoked by the unperceived but commonly experienced video-screen flicker were recorded in the LGN, optic radiation, and V1/V2 visual areas. This study provides topographic and temporal propagation characteristics of steady state visual-evoked potentials along human visual pathways. We discuss the possible relationship between the oscillating signal recorded in subcortical and cortical areas and the electroencephalogram abnormalities observed in patients suffering from photosensitive epilepsy, particularly video-game epilepsy. The consequences of high temporal frequency visual stimuli delivered by ubiquitous video screens on epilepsy, headaches, and eyestrain must be considered.

Oxaloacetate decreases the infarct size and attenuates the reduction in evoked responses after photothrombotic focal ischemia in the rat cortex.

PubMed

Nagy, David; Marosi, Mate; Kis, Zsolt; Farkas, Tamas; Rakos, Gabriella; Vecsei, Laszlo; Teichberg, Vivian I; Toldi, Jozsef

2009-09-01

A traumatic brain injury or a focal brain lesion is followed by acute excitotoxicity caused by the presence of abnormally high glutamate (Glu) levels in the cerebrospinal and interstitial fluids. It has recently been demonstrated that this excess Glu in the brain can be eliminated into the blood following the intravenous administration of oxaloacetate (OxAc), which, by scavenging the blood Glu, induces an enhanced and neuroprotective brain-to-blood Glu efflux. In this study, we subjected rats to a photothrombotic lesion and treated them after the illumination with a single 30-min-long administration of OxAc (1.2 mg/100 g, i.v.). Following induction of the lesion, we measured the infarct size and the amplitudes of the somatosensory evoked potentials (SEPs) as recorded from the skull surface. The photothrombotic lesion resulted in appreciably decreased amplitudes of the evoked potentials, but OxAc administration significantly attenuated this reduction, and also the infarct size assessed histologically. We suggest that the neuroprotective effects of OxAc are due to its blood Glu-scavenging activity, which, by increasing the brain-to-blood Glu efflux, reduces the excess Glu responsible for the anatomical and functional correlates of the ischemia, as evaluated by electrophysiological evoked potential (EP) measurements.

Cortical neurons and networks are dormant but fully responsive during isoelectric brain state.

PubMed

Altwegg-Boussac, Tristan; Schramm, Adrien E; Ballestero, Jimena; Grosselin, Fanny; Chavez, Mario; Lecas, Sarah; Baulac, Michel; Naccache, Lionel; Demeret, Sophie; Navarro, Vincent; Mahon, Séverine; Charpier, Stéphane

2017-09-01

A continuous isoelectric electroencephalogram reflects an interruption of endogenously-generated activity in cortical networks and systematically results in a complete dissolution of conscious processes. This electro-cerebral inactivity occurs during various brain disorders, including hypothermia, drug intoxication, long-lasting anoxia and brain trauma. It can also be induced in a therapeutic context, following the administration of high doses of barbiturate-derived compounds, to interrupt a hyper-refractory status epilepticus. Although altered sensory responses can be occasionally observed on an isoelectric electroencephalogram, the electrical membrane properties and synaptic responses of individual neurons during this cerebral state remain largely unknown. The aim of the present study was to characterize the intracellular correlates of a barbiturate-induced isoelectric electroencephalogram and to analyse the sensory-evoked synaptic responses that can emerge from a brain deprived of spontaneous electrical activity. We first examined the sensory responsiveness from patients suffering from intractable status epilepticus and treated by administration of thiopental. Multimodal sensory responses could be evoked on the flat electroencephalogram, including visually-evoked potentials that were significantly amplified and delayed, with a high trial-to-trial reproducibility compared to awake healthy subjects. Using an analogous pharmacological procedure to induce prolonged electro-cerebral inactivity in the rat, we could describe its cortical and subcortical intracellular counterparts. Neocortical, hippocampal and thalamo-cortical neurons were all silent during the isoelectric state and displayed a flat membrane potential significantly hyperpolarized compared with spontaneously active control states. Nonetheless, all recorded neurons could fire action potentials in response to intracellularly injected depolarizing current pulses and their specific intrinsic electrophysiological features were preserved. Manipulations of the membrane potential and intracellular injection of chloride in neocortical neurons failed to reveal an augmented synaptic inhibition during the isoelectric condition. Consistent with the sensory responses recorded from comatose patients, large and highly reproducible somatosensory-evoked potentials could be generated on the inactive electrocorticogram in rats. Intracellular recordings revealed that the underlying neocortical pyramidal cells responded to sensory stimuli by complex synaptic potentials able to trigger action potentials. As in patients, sensory responses in the isoelectric state were delayed compared to control responses and exhibited an elevated reliability during repeated stimuli. Our findings demonstrate that during prolonged isoelectric brain state neurons and synaptic networks are dormant rather than excessively inhibited, conserving their intrinsic properties and their ability to integrate and propagate environmental stimuli. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Vibration-Induced Kinesthetic Illusions and Corticospinal Excitability Changes.

PubMed

Mancheva, Kapka; Rollnik, Jens D; Wolf, Werner; Dengler, Reinhard; Kossev, Andon

2017-01-01

The authors' aim was to investigate the changes of corticospinal excitability during kinesthetic illusions induced by tendon vibration. Motor-evoked potentials in response to transcranial magnetic stimulation were recorded from the vibrated flexor carpi radialis and its antagonist, extensor carpi radialis. The illusions were evoked under vision conditions without feedback for the position of the wrist (open or closed eyes). In these two conditions motor-evoked potential changes during vibration in the antagonist were not identical. This discrepancy may be a result of 2 simultaneously acting, different and opposite influences and the balance between them depends on visual conditions. Thus, the illusion was accompanied by the facilitation of corticospinal excitability in both vibrated muscle and its antagonist.

Relationship between median nerve somatosensory evoked potentials and spinal cord injury levels in patients with quadriplegia.

PubMed

de Arruda Serra Gaspar, M I F; Cliquet, A; Fernandes Lima, V M; de Abreu, D C C

2009-05-01

Cross-sectional study. To observe if there is a relationship between the level of injury by the American Spinal Cord Injury Association (ASIA) and cortical somatosensory evoked potential (SSEP) recordings of the median nerve in patients with quadriplegia. Rehabilitation Outpatient Clinic at the university hospital in Brazil. Fourteen individuals with quadriplegia and 8 healthy individuals were evaluated. Electrophysiological assessment of the median nerve was performed by evoked potential equipment. The injury level was obtained by ASIA. N(9), N(13) and N(20) were analyzed based on the presence or absence of responses. The parameters used for analyzing these responses were the latency and the amplitude. Data were analyzed using mixed-effect models. N(9) responses were found in all patients with quadriplegia with a similar latency and amplitude observed in healthy individuals; N(13) responses were not found in any patients with quadriplegia. N(20) responses were not found in C5 patients with quadriplegia but it was present in C6 and C7 patients. Their latencies were similar to healthy individuals (P>0.05) but the amplitudes were decreased (P<0.05). This study suggests that the SSEP responses depend on the injury level, considering that the individuals with C6 and C7 injury levels, both complete and incomplete, presented SSEP recordings in the cortical area. It also showed a relationship between the level of spinal cord injury assessed by ASIA and the median nerve SSEP responses, through the latency and amplitude recordings.

SEPs to finger joint input lack the N20-P20 response that is evoked by tactile inputs: contrast between cortical generators in areas 3b and 2 in humans.

PubMed

Desmedt, J E; Ozaki, I

1991-01-01

A method using a DC servo motor is described to produce brisk angular movements at finger interphalangeal joints in humans. Small passive flexions of 2 degrees elicited sizable somatosensory evoked potentials (SEPs) starting with a contralateral positive P34 parietal response thought to reflect activation of a radial equivalent dipole generator in area 2 which receives joint inputs. By contrast, electric stimulation of tactile (non-joint) inputs from the distal phalanx evoked the usual contralateral negative N20 reflecting a tangential equivalent dipole generator in area 3b. Finger joint inputs also evoked a precentral positivity equivalent to the P22 of motor area 4, and a large frontal negativity equivalent to N30. It is suggested that natural stimulation allows human SEP components to be differentiated in conjunction with distinct cortical somatotopic projections.

Use of 64-channel electroencephalography to study neural otolith-evoked responses.

PubMed

McNerney, Kathleen M; Lockwood, Alan H; Coad, Mary Lou; Wack, David S; Burkard, Robert F

2011-03-01

The vestibular evoked myogenic potential (VEMP) is a myogenic response that can be used clinically to evaluate the function of the saccule. However, to date, little is known about the thalamo-cortical representation of saccular activation. It is important to understand all aspects of the VEMP, as this test is currently used clinically in the evaluation of saccular function. To identify the areas of the brain that are activated in response to stimuli used clinically to evoke the VEMP. Electroencephalography (EEG) recordings combined with current density analyses were used to identify the areas of the brain that are activated in response to stimuli presented above VEMP threshold (500 Hz, 120 dB peak SPL [pSPL] tone bursts), as compared to stimuli presented below VEMP threshold (90 dB pSPL, 500 Hz tone bursts). Ten subjects without any history of balance or hearing impairment participated in the study. The neural otolith-evoked responses (NOERs) recorded in response to stimuli presented below VEMP threshold were absent or smaller than NOERs that were recorded in response to stimuli presented above VEMP threshold. Subsequent analyses with source localization techniques, followed by statistical analysis with SPM5 (Statistical Parametric Mapping), revealed several areas that were activated in response to the 120 dB pSPL tone bursts. These areas included the primary visual cortex, the precuneus, the precentral gyrus, the medial temporal gyrus, and the superior temporal gyrus. The present study found a number of specific brain areas that may be activated by otolith stimulation. Given the findings and source localization techniques (which required limited input from the investigator as to where the sources are believed to be located in the brain) used in the present study as well as the similarity in findings between studies employing galvanic stimuli, fMRI (functional magnetic resonance imaging), and scalp-recorded potentials in response to VEMP-eliciting stimuli, our study provides additional evidence that these brain regions are activated in response to stimuli that can be used clinically to evoke the VEMP. American Academy of Audiology.

Fast calcium transients translate the distribution and conduction of neural activity in different regions of a single sensory neuron.

PubMed

Purali, Nuhan

2017-09-01

In the present study, cytosolic calcium concentration changes were recorded in response to various forms of excitations, using the fluorescent calcium indicator dye OG-BAPTA1 together with the current or voltage clamp methods in stretch receptor neurons of crayfish. A single action potential evoked a rise in the resting calcium level in the axon and axonal hillock, whereas an impulse train or a large saturating current injection would be required to evoke an equivalent response in the dendrite region. Under voltage clamp conditions, amplitude differences between axon and dendrite responses vanished completely. The fast activation time and the modulation of the response by extracellular calcium concentration changes indicated that the evoked calcium transients might be mediated by calcium entry into the cytosol through a voltage-gated calcium channel. The decay of the responses was slow and sensitive to extracellular sodium and calcium concentrations as well as exposure to 1-10 mM NiCl 2 and 10-500 µM lanthanum. Thus, a sodium calcium exchanger and a calcium ATPase might be responsible for calcium extrusion from the cytosol. Present results indicate that the calcium indicator OG-BAPTA1 might be an efficient but indirect way of monitoring regional membrane potential differences in a single neuron.

Automatic classification of visual evoked potentials based on wavelet decomposition

NASA Astrophysics Data System (ADS)

Stasiakiewicz, Paweł; Dobrowolski, Andrzej P.; Tomczykiewicz, Kazimierz

2017-04-01

Diagnosis of part of the visual system, that is responsible for conducting compound action potential, is generally based on visual evoked potentials generated as a result of stimulation of the eye by external light source. The condition of patient's visual path is assessed by set of parameters that describe the time domain characteristic extremes called waves. The decision process is compound therefore diagnosis significantly depends on experience of a doctor. The authors developed a procedure - based on wavelet decomposition and linear discriminant analysis - that ensures automatic classification of visual evoked potentials. The algorithm enables to assign individual case to normal or pathological class. The proposed classifier has a 96,4% sensitivity at 10,4% probability of false alarm in a group of 220 cases and area under curve ROC equals to 0,96 which, from the medical point of view, is a very good result.

Frequency-tuning characteristics of cervical and ocular vestibular evoked myogenic potentials induced by air-conducted tone bursts.

PubMed

Park, Hong Ju; Lee, In-Sik; Shin, Jung Eun; Lee, Yeo Jin; Park, Mun Su

2010-01-01

To better characterize both ocular and cervical vestibular evoked myogenic potentials (VEMP) responses at different frequencies of sound in 20 normal subjects. Cervical and ocular VEMPs were recorded. The intensities of sound stimulation decreased from the maximal intensity, until no responses were evoked. Thresholds, amplitudes, latencies and interaural amplitude difference ratio (IADR) at the maximal stimulation were calculated. Both tests showed the similar frequency tuning, with the lowest threshold and highest amplitude for 500-Hz tone-burst stimuli. Sound stimulation at 500Hz showed the response rates of 100% in both tests. Cervical VEMPs showed higher incidence than ocular VEMPs. Ocular VEMP thresholds were significantly higher than those of cervical VEMP. Cervical VEMP amplitudes were significantly higher than ocular VEMP amplitudes. IADRs of ocular and cervical VEMPs did not differ significantly. Ocular VEMP showed the similar frequency tuning to cervical VEMP. Cervical VEMP responses showed higher incidence, lower thresholds and larger amplitudes than ocular VEMP. Cervical VEMP is a more reliable measure than ocular VEMP, though the results of both tests will be complementary. Five hundred Hertz is the optimal frequency to use. Copyright 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Auditory evoked potentials to abrupt pitch and timbre change of complex tones: electrophysiological evidence of 'streaming'?

PubMed

Jones, S J; Longe, O; Vaz Pato, M

1998-03-01

Examination of the cortical auditory evoked potentials to complex tones changing in pitch and timbre suggests a useful new method for investigating higher auditory processes, in particular those concerned with 'streaming' and auditory object formation. The main conclusions were: (i) the N1 evoked by a sudden change in pitch or timbre was more posteriorly distributed than the N1 at the onset of the tone, indicating at least partial segregation of the neuronal populations responsive to sound onset and spectral change; (ii) the T-complex was consistently larger over the right hemisphere, consistent with clinical and PET evidence for particular involvement of the right temporal lobe in the processing of timbral and musical material; (iii) responses to timbral change were relatively unaffected by increasing the rate of interspersed changes in pitch, suggesting a mechanism for detecting the onset of a new voice in a constantly modulated sound stream; (iv) responses to onset, offset and pitch change of complex tones were relatively unaffected by interfering tones when the latter were of a different timbre, suggesting these responses must be generated subsequent to auditory stream segregation.

Evoked potential recording during echolocation in a false killer whale Pseudorca crassidens (L)

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nachtigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

2003-05-01

Auditory brainstem responses (ABRs) were recorded in a false killer whale while the animal echolocated a target. The ABR collection was triggered by echolocation clicks of the animal. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation with experimenter generated clicks showed that the first set of waves may be a response to the emitted click whereas the second one may be a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds that may differ by more than 40 dB near the animal's head. This finding indicates the presence of some mechanism of releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

Infrared neural stimulation (INS) inhibits electrically evoked neural responses in the deaf white cat

NASA Astrophysics Data System (ADS)

Richter, Claus-Peter; Rajguru, Suhrud M.; Robinson, Alan; Young, Hunter K.

2014-03-01

Infrared neural stimulation (INS) has been used in the past to evoke neural activity from hearing and partially deaf animals. All the responses were excitatory. In Aplysia californica, Duke and coworkers demonstrated that INS also inhibits neural responses [1], which similar observations were made in the vestibular system [2, 3]. In deaf white cats that have cochleae with largely reduced spiral ganglion neuron counts and a significant degeneration of the organ of Corti, no cochlear compound action potentials could be observed during INS alone. However, the combined electrical and optical stimulation demonstrated inhibitory responses during irradiation with infrared light.

Heart Rate Response of Professional Musicians When Playing Music.

PubMed

Vellers, Heather L; Irwin, Conor; Lightfoot, J T

2015-06-01

The primary aim was to determine the level of physiological stress evoked while playing music in a standing position as indicated by heart rate (HR) response. A secondary aim was to analyze the effect of music genre (classic rock, western, contemporary Christian, and metal rock) on the relative HR response. Lastly, we considered potential physiological initiators of the music-playing-induced HR response. HR response was monitored in 27 professional musicians (3 women, 24 men) between the ages of 21 and 67 yrs old during rehearsal and public performances. The percent maximal HR (%MHR) evoked was determined by taking a percentage of the age-predicted maximal HR for each musician and comparing the average %MHR in each genre during public and rehearsal events. The role of the potential initiators of these responses (e.g., number of years playing in public, event type, instrument type, tempo, etc.) was determined using multiple regression analyses. The overall average %MHR responses were 52 ± 5% and 59 ± 5% during rehearsal and public performances, respectively, with genre type having a significant effect on the HR response (p=0.01). Body mass index and tempo were each found to be significant contributors to the HR response while playing music (r²=0.506, p=0.001). Playing music professionally evokes considerable increases in HR response, with music genre influencing the level of the physiological response. We concluded that 50% of the HR response while playing music was associated with body mass index, music tempo, and instrument type.

Auditory brain stem response and cortical evoked potentials in children with type 1 diabetes mellitus.

PubMed

Radwan, Heba Mohammed; El-Gharib, Amani Mohamed; Erfan, Adel Ali; Emara, Afaf Ahmad

2017-05-01

Delay in ABR and CAEPs wave latencies in children with type 1DM indicates that there is abnormality in the neural conduction in DM patients. The duration of DM has greater effect on auditory function than the control of DM. Diabetes mellitus (DM) is a common endocrine and metabolic disorder. Evoked potentials offer the possibility to perform a functional evaluation of neural pathways in the central nervous system. To investigate the effect of type 1 diabetes mellitus (T1DM) on auditory brain stem response (ABR) and cortical evoked potentials (CAEPs). This study included two groups: a control group (GI), which consisted of 20 healthy children with normal peripheral hearing, and a study group (GII), which consisted of 30 children with type I DM. Basic audiological evaluation, ABR, and CAEPs were done in both groups. Delayed absolute latencies of ABR and CAEPs waves were found. Amplitudes showed no significant difference between both groups. Positive correlation was found between ABR wave latencies and duration of DM. No correlation was found between ABR, CAEPs, and glycated hemoglobin.

Axono-cortical evoked potentials: A proof-of-concept study.

PubMed

Mandonnet, E; Dadoun, Y; Poisson, I; Madadaki, C; Froelich, S; Lozeron, P

2016-04-01

Awake surgery is currently considered the best method to tailor intraparenchymatous resections according to functional boundaries. However, the exact mechanisms by which electrical stimulation disturbs behavior remain largely unknown. In this case report, we describe a new method to explore the propagation toward cortical sites of a brief pulse applied to an eloquent white matter pathway. We present a patient, operated on in awake condition for removal of a cavernoma of the left ventral premotor cortex. At the end of the resection, the application of 60Hz stimulation in the white matter of the operculum induced anomia. Stimulating the same site at a frequency of 1Hz during 70seconds allowed to record responses on electrodes put over Broca's area and around the inferior part of central sulcus. Axono-cortical evoked potentials were then obtained by averaging unitary responses, time-locked to the stimulus. We then discuss the origin of these evoked axono-cortical potentials and the likely pathway connecting the stimulation site to the recorded cortical sites. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Cellular responses to nicotinic receptor activation are decreased after prolonged exposure to galantamine in human neuroblastoma cells.

PubMed

Barik, Jacques; Dajas-Bailador, Federico; Wonnacott, Susan

2005-08-01

In this study, we have examined cellular responses of neuroblastoma SH-SY5Y cells after chronic treatment with galantamine, a drug used to treat Alzheimer's disease that has a dual mechanism of action: inhibition of acetylcholinesterase and allosteric potentiation of nicotinic acetylcholine receptors (nAChR). Acute experiments confirmed that maximum potentiation of nicotinic responses occurs at 1 microM galantamine; hence this concentration was chosen for chronic treatment. Exposure to 1 microM galantamine for 4 days decreased Ca(2+) responses (by 19.8+/-3.6%) or [(3)H]noradrenaline ([(3)H]NA) release (by 23.9+/-3.3%) elicited by acute application of nicotine. KCl-evoked increases in intracellular Ca(2+) were also inhibited by 10.0+/-1.9% after 4 days' treatment with galantamine. These diminished responses are consistent with the downregulation of downstream cellular processes. Ca(2+) responses evoked by activation of muscarinic acetylcholine receptors were unaffected by chronic galantamine treatment. Exposure to the more potent acetylcholinesterase inhibitor rivastigmine (1 microM) for 4 days failed to alter nicotine-, KCl-, or muscarinic receptor-evoked increases in intracellular Ca(2+). These observations support the hypothesis that chronic galantamine exerts its effects through interaction with nAChR in this cell line. Exposure to 10 microM nicotine for 4 days produced decreases in acute nicotine- (18.0+/-3.5%) and KCl-evoked Ca(2+) responses (10.6+/-2.5%) and nicotine-evoked [(3)H]NA release (26.0+/-3.3%) that are comparable to the effects of a corresponding exposure to galantamine. Treatment with 1 microM galantamine did not alter numbers of [(3)H]epibatidine-binding sites in SH-SY5Y cells, in contrast to 62% upregulation of these sites in response to 10 microM nicotine. Thus, chronic galantamine acts at nAChR to decrease subsequent functional responses to acute stimulation with nicotine or KCl. This effect appears to be independent of the upregulation of nAChR-binding sites.

Recording Visual Evoked Potentials and Auditory Evoked P300 at 9.4T Static Magnetic Field

PubMed Central

Hahn, David; Boers, Frank; Shah, N. Jon

2013-01-01

Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4T were not different from those recorded at 0T. The amplitudes of ERPs were higher at 9.4T when compared to recordings at 0T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses. PMID:23650538

Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

PubMed

Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

2013-01-01

Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

Vestibular evoked myogenic potential (Vemp): evaluation of responses in normal subjects.

PubMed

Felipe, Lilian; Santos, Marco Aurélio Rocha; Gonçalves, Denise Utsch

2008-01-01

the Vestibular Evoked Myogenic Potential (Vemp) is formed by myogenic neurophysiologic responses activated by high-intensity sound stimulation. The response is registered through surface electromyography of the cervical muscles during muscle contraction. The acoustic stimuli activate the saccular macula, the vestibular inferior nerve and the pathways related to the vestibule-spinal descendant nerves. to describe Vemp parameters in a normal population. thirty adults, 13 men and 17 women with no otoneurological complaints were selected. The stimuli were 200 tone burst, with a frequency of 1Hz and intensity of 118 dB Na, band-pass filter ranging from 10Hz to 1500Hz. The first potential biphasic P13-N23 wave was analyzed. no significant difference was observed between the sides of stimulation in terms of latency and amplitude. However, a statistically significant difference was found for amplitude between genders. Vemp demonstrated to be a reliable instrument in the clinical assessment of the vestibular function.

Membrane potential correlates of sensory perception in mouse barrel cortex.

PubMed

Sachidhanandam, Shankar; Sreenivasan, Varun; Kyriakatos, Alexandros; Kremer, Yves; Petersen, Carl C H

2013-11-01

Neocortical activity can evoke sensory percepts, but the cellular mechanisms remain poorly understood. We trained mice to detect single brief whisker stimuli and report perceived stimuli by licking to obtain a reward. Pharmacological inactivation and optogenetic stimulation demonstrated a causal role for the primary somatosensory barrel cortex. Whole-cell recordings from barrel cortex neurons revealed membrane potential correlates of sensory perception. Sensory responses depended strongly on prestimulus cortical state, but both slow-wave and desynchronized cortical states were compatible with task performance. Whisker deflection evoked an early (<50 ms) reliable sensory response that was encoded through cell-specific reversal potentials. A secondary late (50-400 ms) depolarization was enhanced on hit trials compared to misses. Optogenetic inactivation revealed a causal role for late excitation. Our data reveal dynamic processing in the sensory cortex during task performance, with an early sensory response reliably encoding the stimulus and later secondary activity contributing to driving the subjective percept.

Electrocortical amplification for emotionally arousing natural scenes: The contribution of luminance and chromatic visual channels

PubMed Central

Miskovic, Vladimir; Martinovic, Jasna; Wieser, Matthias M.; Petro, Nathan M.; Bradley, Margaret M.; Keil, Andreas

2015-01-01

Emotionally arousing scenes readily capture visual attention, prompting amplified neural activity in sensory regions of the brain. The physical stimulus features and related information channels in the human visual system that contribute to this modulation, however, are not known. Here, we manipulated low-level physical parameters of complex scenes varying in hedonic valence and emotional arousal in order to target the relative contributions of luminance based versus chromatic visual channels to emotional perception. Stimulus-evoked brain electrical activity was measured during picture viewing and used to quantify neural responses sensitive to lower-tier visual cortical involvement (steady-state visual evoked potentials) as well as the late positive potential, reflecting a more distributed cortical event. Results showed that the enhancement for emotional content was stimulus-selective when examining the steady-state segments of the evoked visual potentials. Response amplification was present only for low spatial frequency, grayscale stimuli, and not for high spatial frequency, red/green stimuli. In contrast, the late positive potential was modulated by emotion regardless of the scene’s physical properties. Our findings are discussed in relation to neurophysiologically plausible constraints operating at distinct stages of the cortical processing stream. PMID:25640949

Electrocortical amplification for emotionally arousing natural scenes: the contribution of luminance and chromatic visual channels.

PubMed

Miskovic, Vladimir; Martinovic, Jasna; Wieser, Matthias J; Petro, Nathan M; Bradley, Margaret M; Keil, Andreas

2015-03-01

Emotionally arousing scenes readily capture visual attention, prompting amplified neural activity in sensory regions of the brain. The physical stimulus features and related information channels in the human visual system that contribute to this modulation, however, are not known. Here, we manipulated low-level physical parameters of complex scenes varying in hedonic valence and emotional arousal in order to target the relative contributions of luminance based versus chromatic visual channels to emotional perception. Stimulus-evoked brain electrical activity was measured during picture viewing and used to quantify neural responses sensitive to lower-tier visual cortical involvement (steady-state visual evoked potentials) as well as the late positive potential, reflecting a more distributed cortical event. Results showed that the enhancement for emotional content was stimulus-selective when examining the steady-state segments of the evoked visual potentials. Response amplification was present only for low spatial frequency, grayscale stimuli, and not for high spatial frequency, red/green stimuli. In contrast, the late positive potential was modulated by emotion regardless of the scene's physical properties. Our findings are discussed in relation to neurophysiologically plausible constraints operating at distinct stages of the cortical processing stream. Copyright © 2015 Elsevier B.V. All rights reserved.

Emotional body-word conflict evokes enhanced n450 and slow potential.

PubMed

Ma, Jianling; Liu, Chang; Zhong, Xin; Wang, Lu; Chen, Xu

2014-01-01

Emotional conflict refers to the influence of task irrelevant affective stimuli on current task set. Previously used emotional face-word tasks have produced certain electrophysiological phenomena, such as an enhanced N450 and slow potential; however, it remains unknown whether these effects emerge in other tasks. The present study used an emotional body-word conflict task to investigate the neural dynamics of emotional conflict as reflected by response time, accuracy, and event-related potentials, which were recorded with the aim of replicating the previously observed N450 and slow potential effect. Results indicated increased response time and decreased accuracy in the incongruent condition relative to the congruent condition, indicating a robust interference effect. Furthermore, the incongruent condition evoked pronounced N450 amplitudes and a more positive slow potential, which might be associated with conflict-monitoring and conflict resolution. The present findings extend our understanding of emotional conflict to the body-word domain.

Effect of caffeine on vestibular evoked myogenic potential: a systematic review with meta-analysis.

PubMed

Souza, Maria Eduarda Di Cavalcanti Alves de; Costa, Klinger Vagner Teixeira da; Menezes, Pedro de Lemos

2017-12-24

Caffeine can be considered the most consumed drug by adults worldwide, and can be found in several foods, such as chocolate, coffee, tea, soda and others. Overall, caffeine in moderate doses, results in increased physical and intellectual productivity, increases the capacity of concentration and reduces the time of reaction to sensory stimuli. On the other hand, high doses can cause noticeable signs of mental confusion and error induction in intellectual tasks, anxiety, restlessness, muscle tremors, tachycardia, labyrinthine changes, and tinnitus. Considering that the vestibular evoked myogenic potential is a clinical test that evaluates the muscular response of high intensity auditory stimulation, the present systematic review aimed to analyze the effects of caffeine on vestibular evoked myogenic potential. This study consisted of the search of the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to intervention (caffeine or coffee consumption) and the primary outcome (vestibular evoked myogenic potential). Based on the 253 potentially relevant articles identified through the database search, only two full-text publications were retrieved for further evaluation, which were maintained for qualitative analysis. Analyzing the articles found, caffeine has no effect on vestibular evoked myogenic potential in normal individuals. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Network activity influences the subthreshold and spiking visual responses of pyramidal neurons in the three-layer turtle cortex.

PubMed

Wright, Nathaniel C; Wessel, Ralf

2017-10-01

A primary goal of systems neuroscience is to understand cortical function, typically by studying spontaneous and stimulus-modulated cortical activity. Mounting evidence suggests a strong and complex relationship exists between the ongoing and stimulus-modulated cortical state. To date, most work in this area has been based on spiking in populations of neurons. While advantageous in many respects, this approach is limited in scope: it records the activity of a minority of neurons and gives no direct indication of the underlying subthreshold dynamics. Membrane potential recordings can fill these gaps in our understanding, but stable recordings are difficult to obtain in vivo. Here, we recorded subthreshold cortical visual responses in the ex vivo turtle eye-attached whole brain preparation, which is ideally suited for such a study. We found that, in the absence of visual stimulation, the network was "synchronous"; neurons displayed network-mediated transitions between hyperpolarized (Down) and depolarized (Up) membrane potential states. The prevalence of these slow-wave transitions varied across turtles and recording sessions. Visual stimulation evoked similar Up states, which were on average larger and less reliable when the ongoing state was more synchronous. Responses were muted when immediately preceded by large, spontaneous Up states. Evoked spiking was sparse, highly variable across trials, and mediated by concerted synaptic inputs that were, in general, only very weakly correlated with inputs to nearby neurons. Together, these results highlight the multiplexed influence of the cortical network on the spontaneous and sensory-evoked activity of individual cortical neurons. NEW & NOTEWORTHY Most studies of cortical activity focus on spikes. Subthreshold membrane potential recordings can provide complementary insight, but stable recordings are difficult to obtain in vivo. Here, we recorded the membrane potentials of cortical neurons during ongoing and visually evoked activity. We observed a strong relationship between network and single-neuron evoked activity spanning multiple temporal scales. The membrane potential perspective of cortical dynamics thus highlights the influence of intrinsic network properties on visual processing. Copyright © 2017 the American Physiological Society.

The effects of neck flexion on cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in related sensory cortices

PubMed Central

2012-01-01

Background A flexed neck posture leads to non-specific activation of the brain. Sensory evoked cerebral potentials and focal brain blood flow have been used to evaluate the activation of the sensory cortex. We investigated the effects of a flexed neck posture on the cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in the related sensory cortices. Methods Twelve healthy young adults received right visual hemi-field, binaural auditory and left median nerve stimuli while sitting with the neck in a resting and flexed (20° flexion) position. Sensory evoked potentials were recorded from the right occipital region, Cz in accordance with the international 10–20 system, and 2 cm posterior from C4, during visual, auditory and somatosensory stimulations. The oxidative-hemoglobin concentration was measured in the respective sensory cortex using near-infrared spectroscopy. Results Latencies of the late component of all sensory evoked potentials significantly shortened, and the amplitude of auditory evoked potentials increased when the neck was in a flexed position. Oxidative-hemoglobin concentrations in the left and right visual cortices were higher during visual stimulation in the flexed neck position. The left visual cortex is responsible for receiving the visual information. In addition, oxidative-hemoglobin concentrations in the bilateral auditory cortex during auditory stimulation, and in the right somatosensory cortex during somatosensory stimulation, were higher in the flexed neck position. Conclusions Visual, auditory and somatosensory pathways were activated by neck flexion. The sensory cortices were selectively activated, reflecting the modalities in sensory projection to the cerebral cortex and inter-hemispheric connections. PMID:23199306

Multifocal Visual Evoked Potential in Eyes With Temporal Hemianopia From Chiasmal Compression: Correlation With Standard Automated Perimetry and OCT Findings.

PubMed

Sousa, Rafael M; Oyamada, Maria K; Cunha, Leonardo P; Monteiro, Mário L R

2017-09-01

To verify whether multifocal visual evoked potential (mfVEP) can differentiate eyes with temporal hemianopia due to chiasmal compression from healthy controls. To assess the relationship between mfVEP, standard automated perimetry (SAP), and Fourier domain-optical coherence tomography (FD-OCT) macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Twenty-seven eyes with permanent temporal visual field (VF) defects from chiasmal compression on SAP and 43 eyes of healthy controls were submitted to mfVEP and FD-OCT scanning. Multifocal visual evoked potential was elicited using a stimulus pattern of 60 sectors and the responses were averaged for the four quadrants and two hemifields. Optical coherence tomography macular measurements were averaged in quadrants and halves, while peripapillary RNFL thickness was averaged in four sectors around the disc. Visual field loss was estimated in four quadrants and each half of the 24-2 strategy test points. Multifocal visual evoked potential measurements in the two groups were compared using generalized estimated equations, and the correlations between mfVEP, VF, and OCT findings were quantified. Multifocal visual evoked potential-measured temporal P1 and N2 amplitudes were significantly smaller in patients than in controls. No significant difference in amplitude was observed for nasal parameters. A significant correlation was found between mfVEP amplitudes and temporal VF loss, and between mfVEP amplitudes and the corresponding OCT-measured macular and RNFL thickness parameters. Multifocal visual evoked potential amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF and OCT findings, suggesting mfVEP is a useful tool for the detection of visual abnormalities in patients with chiasmal compression.

Radiant energy required for infrared neural stimulation

DOE PAGES

Tan, Xiaodong; Rajguru, Suhrud; Young, Hunter; ...

2015-08-25

Infrared neural stimulation (INS) has been proposed as an alternative method to electrical stimulation because of its spatial selective stimulation. Independent of the mechanism for INS, to translate the method into a device it is important to determine the energy for stimulation required at the target structure. Custom-designed, flat and angle polished fibers, were used to deliver the photons. By rotating the angle polished fibers, the orientation of the radiation beam in the cochlea could be changed. INS-evoked compound action potentials and single unit responses in the central nucleus of the inferior colliculus (ICC) were recorded. X-ray computed tomography wasmore » used to determine the orientation of the optical fiber. Maximum responses were observed when the radiation beam was directed towards the spiral ganglion neurons (SGNs), whereas little responses were seen when the beam was directed towards the basilar membrane. The radiant exposure required at the SGNs to evoke compound action potentials (CAPs) or ICC responses was on average 18.9 ± 12.2 or 10.3 ± 4.9 mJ/cm 2, respectively. For cochlear INS it has been debated whether the radiation directly stimulates the SGNs or evokes a photoacoustic effect. The results support the view that a direct interaction between neurons and radiation dominates the response to INS.« less

Radiant energy required for infrared neural stimulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Xiaodong; Rajguru, Suhrud; Young, Hunter

Infrared neural stimulation (INS) has been proposed as an alternative method to electrical stimulation because of its spatial selective stimulation. Independent of the mechanism for INS, to translate the method into a device it is important to determine the energy for stimulation required at the target structure. Custom-designed, flat and angle polished fibers, were used to deliver the photons. By rotating the angle polished fibers, the orientation of the radiation beam in the cochlea could be changed. INS-evoked compound action potentials and single unit responses in the central nucleus of the inferior colliculus (ICC) were recorded. X-ray computed tomography wasmore » used to determine the orientation of the optical fiber. Maximum responses were observed when the radiation beam was directed towards the spiral ganglion neurons (SGNs), whereas little responses were seen when the beam was directed towards the basilar membrane. The radiant exposure required at the SGNs to evoke compound action potentials (CAPs) or ICC responses was on average 18.9 ± 12.2 or 10.3 ± 4.9 mJ/cm 2, respectively. For cochlear INS it has been debated whether the radiation directly stimulates the SGNs or evokes a photoacoustic effect. The results support the view that a direct interaction between neurons and radiation dominates the response to INS.« less

Effects of pharmacological agents on subcortical resistance shifts

NASA Technical Reports Server (NTRS)

Klivington, K. A.

1975-01-01

Microliter quantities of tetrodotoxin, tetraethylammonium chloride, and picrotoxin injected into the inferior colliculus and superior olive of unanesthetized cats differentially affect the amplitude and waveform of click-evoked potentials and evoked resistance shifts. Tetrodotoxin simultaneously reduces the negative phase of the evoked potential and eliminates the evoked resistance shift. Tetraethylammonium enhances the negative evoked potential component, presumably of postsynaptic origin, without significantly altering evoked resistance shift amplitude. Picrotoxin also enhances the negative evoked potential wave but increases evoked resistance shift amplitude. These findings implicate events associated with postsynaptic membrane depolarization in the production of the evoked resistance shift.

Complexin Mutants Reveal Partial Segregation between Recycling Pathways That Drive Evoked and Spontaneous Neurotransmission

PubMed Central

Sabeva, Nadezhda; Cho, Richard W.; Vasin, Alexander; Gonzalez, Agustin; Littleton, J. Troy

2017-01-01

Synaptic vesicles fuse at morphological specializations in the presynaptic terminal termed active zones (AZs). Vesicle fusion can occur spontaneously or in response to an action potential. Following fusion, vesicles are retrieved and recycled within nerve terminals. It is still unclear whether vesicles that fuse spontaneously or following evoked release share similar recycling mechanisms. Genetic deletion of the SNARE-binding protein complexin dramatically increases spontaneous fusion, with the protein serving as the synaptic vesicle fusion clamp at Drosophila synapses. We examined synaptic vesicle recycling pathways at complexin null neuromuscular junctions, where spontaneous release is dramatically enhanced. We combined loading of the lipophilic dye FM1–43 with photoconversion, electron microscopy, and electrophysiology to monitor evoked and spontaneous recycling vesicle pools. We found that the total number of recycling vesicles was equal to those retrieved through spontaneous and evoked pools, suggesting that retrieval following fusion is partially segregated for spontaneous and evoked release. In addition, the kinetics of FM1–43 destaining and synaptic depression measured in the presence of the vesicle-refilling blocker bafilomycin indicated that spontaneous and evoked recycling pools partially intermix during the release process. Finally, FM1–43 photoconversion combined with electron microscopy analysis indicated that spontaneous recycling preferentially involves synaptic vesicles in the vicinity of AZs, whereas vesicles recycled following evoked release involve a larger intraterminal pool. Together, these results suggest that spontaneous and evoked vesicles use separable recycling pathways and then partially intermix during subsequent rounds of fusion. SIGNIFICANCE STATEMENT Neurotransmitter release involves fusion of synaptic vesicles with the plasma membrane in response to an action potential, or spontaneously in the absence of stimulation. Upon fusion, vesicles are retrieved and recycled, and it is unclear whether recycling pathways for evoked and spontaneous vesicles are segregated after fusion. We addressed this question by taking advantage of preparations lacking the synaptic protein complexin, which have elevated spontaneous release that enables reliable tracking of the spontaneous recycling pool. Our results suggest that spontaneous and evoked recycling pathways are segregated during the retrieval process but can partially intermix during stimulation. PMID:28077717

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon

PubMed Central

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M.; Cooke, Helen J.; Wood, Jackie D.

2009-01-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1–3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1–3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1–3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P < 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles. PMID:19179625

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon.

PubMed

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M; Cooke, Helen J; Wood, Jackie D

2009-04-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1-3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1-3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1-3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P<0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles.

Dose-response characteristics of methylphenidate on locomotor behavior and on sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats.

PubMed

Yang, Pamela B; Swann, Alan C; Dafny, Nachum

2006-01-17

Methylphenidate (MPD) is a psychostimulant commonly prescribed for attention deficit/hyperactivity disorder. The mode of action of the brain circuitry responsible for initiating the animals' behavior in response to psychostimulants is not well understood. There is some evidence that psychostimulants activate the ventral tegmental area (VTA), nucleus accumbens (NAc), and prefrontal cortex (PFC). The present study was designed to investigate the acute dose-response of MPD (0.6, 2.5, and 10.0 mg/kg) on locomotor behavior and sensory evoked potentials recorded from the VTA, NAc, and PFC in freely behaving rats previously implanted with permanent electrodes. For locomotor behavior, adult male Wistar-Kyoto (WKY; n = 39) rats were given saline on experimental day 1 and either saline or an acute injection of MPD (0.6, 2.5, or 10.0 mg/kg, i.p.) on experimental day 2. Locomotor activity was recorded for 2-h post injection on both days using an automated, computerized activity monitoring system. Electrophysiological recordings were also performed in the adult male WKY rats (n = 10). Five to seven days after the rats had recovered from the implantation of electrodes, each rat was placed in a sound-insulated, electrophysiological test chamber where its sensory evoked field potentials were recorded before and after saline and 0.6, 2.5, and 10.0 mg/kg MPD injection. Time interval between injections was 90 min. Results showed an increase in locomotion with dose-response characteristics, while a dose-response decrease in amplitude of the components of sensory evoked field responses of the VTA, NAc, and PFC neurons. For example, the P3 component of the sensory evoked field response of the VTA decreased by 19.8% +/- 7.4% from baseline after treatment of 0.6 mg/kg MPD, 37.8% +/- 5.9% after 2.5 mg/kg MPD, and 56.5% +/- 3.9% after 10 mg/kg MPD. Greater attenuation from baseline was observed in the NAc and PFC. Differences in the intensity of MPD-induced attenuation were also found among these brain areas. These results suggest that an acute treatment of MPD produces electrophysiologically detectable alterations at the neuronal level, as well as observable, behavioral responses. The present study is the first to investigate the acute dose-response effects of MPD on behavior in terms of locomotor activity and in the brain involving the sensory inputs of VTA, NAc, and PFC neurons in intact, non-anesthetized, freely behaving rats previously implanted with permanent electrodes.

Cortical Auditory Evoked Potentials Recorded From Nucleus Hybrid Cochlear Implant Users.

PubMed

Brown, Carolyn J; Jeon, Eun Kyung; Chiou, Li-Kuei; Kirby, Benjamin; Karsten, Sue A; Turner, Christopher W; Abbas, Paul J

2015-01-01

Nucleus Hybrid Cochlear Implant (CI) users hear low-frequency sounds via acoustic stimulation and high-frequency sounds via electrical stimulation. This within-subject study compares three different methods of coordinating programming of the acoustic and electrical components of the Hybrid device. Speech perception and cortical auditory evoked potentials (CAEP) were used to assess differences in outcome. The goals of this study were to determine whether (1) the evoked potential measures could predict which programming strategy resulted in better outcome on the speech perception task or was preferred by the listener, and (2) CAEPs could be used to predict which subjects benefitted most from having access to the electrical signal provided by the Hybrid implant. CAEPs were recorded from 10 Nucleus Hybrid CI users. Study participants were tested using three different experimental processor programs (MAPs) that differed in terms of how much overlap there was between the range of frequencies processed by the acoustic component of the Hybrid device and range of frequencies processed by the electrical component. The study design included allowing participants to acclimatize for a period of up to 4 weeks with each experimental program prior to speech perception and evoked potential testing. Performance using the experimental MAPs was assessed using both a closed-set consonant recognition task and an adaptive test that measured the signal-to-noise ratio that resulted in 50% correct identification of a set of 12 spondees presented in background noise. Long-duration, synthetic vowels were used to record both the cortical P1-N1-P2 "onset" response and the auditory "change" response (also known as the auditory change complex [ACC]). Correlations between the evoked potential measures and performance on the speech perception tasks are reported. Differences in performance using the three programming strategies were not large. Peak-to-peak amplitude of the ACC was not found to be sensitive enough to accurately predict the programming strategy that resulted in the best performance on either measure of speech perception. All 10 Hybrid CI users had residual low-frequency acoustic hearing. For all 10 subjects, allowing them to use both the acoustic and electrical signals provided by the implant improved performance on the consonant recognition task. For most subjects, it also resulted in slightly larger cortical change responses. However, the impact that listening mode had on the cortical change responses was small, and again, the correlation between the evoked potential and speech perception results was not significant. CAEPs can be successfully measured from Hybrid CI users. The responses that are recorded are similar to those recorded from normal-hearing listeners. The goal of this study was to see if CAEPs might play a role either in identifying the experimental program that resulted in best performance on a consonant recognition task or in documenting benefit from the use of the electrical signal provided by the Hybrid CI. At least for the stimuli and specific methods used in this study, no such predictive relationship was found.

Detecting number processing and mental calculation in patients with disorders of consciousness using a hybrid brain-computer interface system.

PubMed

Li, Yuanqing; Pan, Jiahui; He, Yanbin; Wang, Fei; Laureys, Steven; Xie, Qiuyou; Yu, Ronghao

2015-12-15

For patients with disorders of consciousness such as coma, a vegetative state or a minimally conscious state, one challenge is to detect and assess the residual cognitive functions in their brains. Number processing and mental calculation are important brain functions but are difficult to detect in patients with disorders of consciousness using motor response-based clinical assessment scales such as the Coma Recovery Scale-Revised due to the patients' motor impairments and inability to provide sufficient motor responses for number- and calculation-based communication. In this study, we presented a hybrid brain-computer interface that combines P300 and steady state visual evoked potentials to detect number processing and mental calculation in Han Chinese patients with disorders of consciousness. Eleven patients with disorders of consciousness who were in a vegetative state (n = 6) or in a minimally conscious state (n = 3) or who emerged from a minimally conscious state (n = 2) participated in the brain-computer interface-based experiment. During the experiment, the patients with disorders of consciousness were instructed to perform three tasks, i.e., number recognition, number comparison, and mental calculation, including addition and subtraction. In each experimental trial, an arithmetic problem was first presented. Next, two number buttons, only one of which was the correct answer to the problem, flickered at different frequencies to evoke steady state visual evoked potentials, while the frames of the two buttons flashed in a random order to evoke P300 potentials. The patients needed to focus on the target number button (the correct answer). Finally, the brain-computer interface system detected P300 and steady state visual evoked potentials to determine the button to which the patients attended, further presenting the results as feedback. Two of the six patients who were in a vegetative state, one of the three patients who were in a minimally conscious state, and the two patients that emerged from a minimally conscious state achieved accuracies significantly greater than the chance level. Furthermore, P300 potentials and steady state visual evoked potentials were observed in the electroencephalography signals from the five patients. Number processing and arithmetic abilities as well as command following were demonstrated in the five patients. Furthermore, our results suggested that through brain-computer interface systems, many cognitive experiments may be conducted in patients with disorders of consciousness, although they cannot provide sufficient behavioral responses.

Vascular compliance limits during sleep deprivation and recovery sleep.

PubMed

Phillips, Derrick J; Schei, Jennifer L; Rector, David M

2013-10-01

Our previous studies showed that evoked hemodynamic responses are smaller during wake compared to sleep; suggesting neural activity is associated with vascular expansion and decreased compliance. We explored whether prolonged activity during sleep deprivation may exacerbate vascular expansion and blunt hemodynamic responses. Evoked auditory responses were generated with periodic 65 dB speaker clicks over a 72-h period and measured with cortical electrodes. Evoked hemodynamic responses were measured simultaneously with optical techniques using three light-emitting diodes, and a photodiode. Animals were housed in separate 30×30×80 cm enclosures, tethered to a commutator system and maintained on a 12-h light/dark cycle. Food and water were available ad libitum. Seven adult female Sprague-Dawley rats. Following a 24-h baseline recording, sleep deprivation was initiated for 0 to 10 h by gentle handling, followed by a 24-h recovery sleep recording. Evoked electrical and hemodynamic responses were measured before, during, and after sleep deprivation. Following deprivation, evoked hemodynamic amplitudes were blunted. Steady-state oxyhemoglobin concentration increased during deprivation and remained high during the initial recovery period before returning to baseline levels after approximately 9-h. Sleep deprivation resulted in blood vessel expansion and decreased compliance while lower basal neural activity during recovery sleep may allow blood vessel compliance to recover. Chronic sleep restriction or sleep deprivation could push the vasculature to critical levels, limiting blood delivery, and leading to metabolic deficits with the potential for neural trauma.

Calcium released by photolysis of DM-nitrophen stimulates transmitter release at squid giant synapse.

PubMed

Delaney, K R; Zucker, R S

1990-07-01

1. Transmitter release at the squid giant synapse was stimulated by photolytic release of Ca2+ from the 'caged' Ca2+ compound DM-nitrophen (Kaplan & Ellis-Davies, 1988) inserted into presynaptic terminals. 2. Competing binding reactions cause the amount of Ca2+ released by DM-nitrophen photolysis to depend on the concentrations of DM-nitrophen, total Ca2+, Mg+, ATP and native cytoplasmic Ca2+ buffer. Measurements of presynaptic [Ca2+] changes by co-injection of the fluorescent indicator dye Fura-2 show that DM-nitrophen photolysis causes a transient rise in Ca2+ followed by decay within about 150 ms to an increased steady-state level. 3. Rapid photolysis of Ca2(+)-loaded nitrophen within the presynaptic terminal was followed in less than a millisecond by depolarization of the postsynaptic membrane. As with action potential-evoked excitatory postsynaptic potentials (EPSPs), the light-evoked response was partially and reversibly blocked by 1-3 mM-kainic acid which desensitizes postsynaptic glutamate receptors. 4. Release was similar in magnitude and rate to normal action potential-mediated EPSPs. 5. The release of transmitter by photolysis of Ca2(+)-loaded DM-nitrophen was not affected by removal of Ca2+ from the saline or addition of tetrodotoxin. Photolysis of DM-nitrophen injected into presynaptic terminals without added Ca2+ did not stimulate release of transmitter nor did it interfere with normal action potential-mediated release. 6. Stimulation of presynaptic action potentials in Ca2(+)-free saline during the light-evoked response did not elicit increased release of transmitter if the ganglion was bathed in Ca2(+)-free saline, i.e. in the absence of Ca2+ influx. Increasing the intensity of the light or stimulating presynaptic action potentials in Ca2(+)-containing saline increased the release of transmitter. Therefore the failure of presynaptic voltage change to increase transmitter release resulting from release of caged Ca2+ was not due to saturation or inhibition of the release mechanism by light-released Ca2+. 7. Decreasing the temperature of the preparation increased the delay to onset of the light-evoked response and reduced its amplitude and rate of rise to an extent similar to that observed for action potential-evoked EPSPs.

The startle response and toxicology: Methods, use and interpretation.

EPA Science Inventory

The startle response (SR) is a sensory-evoked motor reflex that has been used successfully in toxicology for decades. Advantages of this procedure include: rapidly objective measurement of a defined neural circuit, measurement of habituation of the response, and a high potential ...

Potentials evoked by chirp-modulated tones: a new technique to evaluate oscillatory activity in the auditory pathway.

PubMed

Artieda, J; Valencia, M; Alegre, M; Olaziregi, O; Urrestarazu, E; Iriarte, J

2004-03-01

Steady-state potentials are oscillatory responses generated by a rhythmic stimulation of a sensory pathway. The frequency of the response, which follows the frequency of stimulation, is maximal at a stimulus rate of 40 Hz for auditory stimuli. The exact cause of these maximal responses is not known, although some authors have suggested that they might be related to the 'working frequency' of the auditory cortex. Testing of the responses to different frequencies of stimulation may be lengthy if a single frequency is studied at a time. Our aim was to develop a fast technique to explore the oscillatory response to auditory stimuli, using a tone modulated in amplitude by a sinusoid whose frequency increases linearly in frequency ('chirp') from 1 to 120 Hz. Time-frequency transforms were used for the analysis of the evoked responses in 10 subjects. Also, we analyzed whether the peaks in these responses were due to increases of amplitude or to phase-locking phenomena, using single-sweep time-frequency transforms and inter-trial phase analysis. The pattern observed in the time-frequency transform of the chirp-evoked potential was very similar in all subjects: a diagonal band of energy was observed, corresponding to the frequency of modulation at each time instant. Two components were present in the band, one around 45 Hz (30-60 Hz) and a smaller one between 80 and 120 Hz. Inter-trial phase analysis showed that these components were mainly due to phase locking phenomena. A simultaneous testing of the amplitude-modulation-following oscillatory responses to auditory stimulation is feasible using a tone modulated in amplitude at increasing frequencies. The maximal energies found at stimulation frequencies around 40 Hz are probably due to increased phase-locking of the individual responses.

Electroencephalogram (EEG) and Magnetoencephalogram (MEG) as Tools for Evaluation of Cognitive Function

NASA Technical Reports Server (NTRS)

Fender, Derek H.; Hestenes, John D.

1985-01-01

We have developed computerized analysis and display techniques to help identify the origins of visually evoked scalped potentials (VESP). The potentials are recorded simultaneously from many electrodes (usually 40 to 48) spaced over the region of the scalp where appreciable evoked potentials are found in response to particular stimulus. Contour mapping algorithms are then used to display the time behavior of equipotential surfaces on the scalp during the VESP. We then use an optimization technique to select the parameters of arrays of current dipole sources within the model until the model equipotential field distribution closely fits the measured data. Computer graphics are then used to display, as a movie, the actual and model scalp potential fields and the parameters of the dipole generators within the model head during the course of VESP activity. We have devised reaction time tests that involve potentially separable stages of cognitive processing and utilize stimuli that produce measurable cognition-related features in the late component of the evoked potential. We have used these techniques to determine the loci in the brain where known cognition-related features in the evoked potential are generated and we have explored the extent to which each of these features can be related to the reaction time tasks. We have also examined the temporal-spatial aspects of their cerebral involvement. Our current work is planned to characterize the age-related changes in the processes performed by such sources. We also use a neuromagnetometer to measure the evoked magnetic fields in similar circumstances; we will discuss the relative merits of the two methodologies.

Scopolamine attenuates auditory cortex response.

PubMed

Deng, Anchun; Liang, Xiaojun; Sun, Yuchen; Xiang, Yanghong; Yang, Junjie; Yan, Jingjing; Sun, Wei

2015-01-01

Scopolamine, a tropane alkaloid drug that mainly acts as an antagonist of muscarinic acetylcholine receptors, was found to reduce the local field potentials (LFP) of auditory cortex (AC) evoked by tone and gap-offsets whose effects may compensate the cortical hyperexcitability related to tinnitus. To study the effects of scopolamine on the AC and the inferior colliculus (IC) of awake rats in order to understand scopolamine's effect on tinnitus and gap detection. Silent gaps (duration varied from 2-100 ms) embedded in otherwise continuous noise were used to elicit AC and IC response. Gap evoked AC and IC field potentials were recorded from awake rats before and after treatment of scopolamine (3 mg/kg, i.m.). Acute injection of scopolamine (3 mg/kg, i.m.) induced a significant reduction of the AC response, but not the IC response, to the offset of the gaps embedded in white noise. The results suggest that scopolamine may reduce AC neural synchrony.

A short latency vestibular evoked potential (VsEP) produced by bone-conducted acoustic stimulation

NASA Astrophysics Data System (ADS)

McAngus Todd, Neil P.; Rosengren, Sally M.; Colebatch, James G.

2003-12-01

In this paper data are presented from an experiment which provides evidence for the existence of a short latency, acoustically evoked potential of probable vestibular origin. The experiment was conducted in two phases using bone-conducted acoustic stimulation. In the first phase subjects were stimulated with 6-ms, 500-Hz tone bursts in order to obtain the threshold VT for vestibular evoked myogenic potentials (VEMP). It was confirmed that the difference between bone-conducted auditory and acoustic vestibular thresholds was slightly over 30 dB. The estimated threshold was then used as a reference value in the second part of the experiment to stimulate subjects over a range of intensities from -6 to +18 dB (re:VT). Averaged EEG recordings were made with eight Ag/AgCl electrodes placed on the scalp at Fpz, F3, F4, F7, F8, Cz, T3, and T4 according to the 10-20 system. Below VT auditory midlatency responses (MLRs) were observed. Above VT two additional potentials appeared: a positivity at about 10 ms (P10) which was maximal at Cz, and a negativity at about 15 ms (N15) which was maximal at Fpz. Extrapolation of the growth functions for the P10 and N15 indicated a threshold close to VT, consistent with a vestibular origin of these potentials. Given the low threshold of vestibular acoustic sensitivity it is possible that this mode may make a contribution to the detection of and affective responses to loud low frequency sounds. The evoked potentials may also have application as a noninvasive and nontraumatic test of vestibular projections to the cortex.

Applications of pain-related evoked potentials and short-latency somatosensory evoked potentials in acupuncture research: a narrative review.

PubMed

Lin, Chi; Ma, Liangxiao; Zhu, Shipeng; Hu, Nijuan; Wang, Pei; Zhang, Peng; Qi, Dandan; Hao, Jie; Li, Jing; Xin, Siyuan; Zhu, Jiang

2015-10-01

To review and discuss the Chinese and English literature on the use of pain-related evoked potentials (PREP) and short-latency somatosensory EP (SLSEP) in acupuncture research. China National Knowledge Infrastructure Database and MEDLINE were searched for the following key words: acupuncture and PREP or SLSEP. Thirty-seven articles were included in the review. Researchers usually use PREPs to study the analgesic effect of acupuncture, observe influential factors, or for mechanistic exploration. In the SLSEP studies, researchers focused on response characteristics of acupuncture, acupoint specificity, and influential factors of the treatment. There were some problems with the study design and conclusions. Researchers could use PREP and SLSEP to objectively validate the effects of acupuncture and explore its mechanisms using nerve electrophysiology. Further studies can benefit from observing more acupoints' effects using PREPs or SLSEPs and investigating the placebo effect of acupuncture.

Brain stem auditory evoked responses in human infants and adults

NASA Technical Reports Server (NTRS)

Hecox, K.; Galambos, R.

1974-01-01

Brain stem evoked potentials were recorded by conventional scalp electrodes in infants (3 weeks to 3 years of age) and adults. The latency of one of the major response components (wave V) is shown to be a function both of click intensity and the age of the subject; this latency at a given signal strength shortens postnatally to reach the adult value (about 6 msec) by 12 to 18 months of age. The demonstrated reliability and limited variability of these brain stem electrophysiological responses provide the basis for an optimistic estimate of their usefulness as an objective method for assessing hearing in infants and adults.

Tachykininergic slow depolarization of motoneurones evoked by descending fibres in the neonatal rat spinal cord.

PubMed

Kurihara, T; Yoshioka, K; Otsuka, M

1995-06-15

1. In the isolated spinal cord of the neonatal rat, repetitive electrical stimulation of the upper cervical region elicited a prolonged depolarization of lumbar motoneurones (L3-5) lasting 1-2 min, which was recorded extracellularly from ventral roots, or intracellularly. 2. This depolarizing response was markedly depressed by the excitatory amino acid receptor antagonists D-(-)-2-amino-5-phosphonovaleric acid (D-APV, 30 microM) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM). The remaining response was further depressed by a 5-hydroxytryptamine (5-HT) receptor antagonist, ketanserin (3 microM). 3. In the presence of these antagonists, a small part of the depolarizing response of slow time course remained, and this response was partially blocked by the tachykinin NK1 receptor antagonists GR71251 (0.3-5 microM) and RP67580 (0.3-1 microM). In contrast, RP68651 (0.3-1 microM), the inactive enantiomer of RP67580, had no effect on the depolarizing response. 4. The slow depolarizing response in the presence of D-APV, CNQX and ketanserin was markedly potentiated by a peptidase inhibitor, thiorphan (1 microM). 5. This descending fibre-evoked slow depolarization became smaller after prolonged treatment (5-7 h) with 5,7-dihydroxytryptamine (10 microM), a neurotoxin for 5-HT neurones. Under such conditions, the effects of thiorphan and GR71251 on the slow depolarization were virtually absent. 6. Under the action of D-APV, CNQX and ketanserin, applications of tachykinins, substance P and neurokinin A produced depolarizing responses of lumbar motoneurones, and the responses were depressed by GR71251 and potentiated by thiorphan. 7. These results suggest that tachykinins contained in serotonergic fibres serve as neurotransmitters mediating the descending fibre-evoked slow excitatory postsynaptic potentials in motoneurones.

Gap-induced reductions of evoked potentials in the auditory cortex: A possible objective marker for the presence of tinnitus in animals.

PubMed

Berger, Joel I; Owen, William; Wilson, Caroline A; Hockley, Adam; Coomber, Ben; Palmer, Alan R; Wallace, Mark N

2018-01-15

Animal models of tinnitus are essential for determining the underlying mechanisms and testing pharmacotherapies. However, there is doubt over the validity of current behavioural methods for detecting tinnitus. Here, we applied a stimulus paradigm widely used in a behavioural test (gap-induced inhibition of the acoustic startle reflex GPIAS) whilst recording from the auditory cortex, and showed neural response changes that mirror those found in the behavioural tests. We implanted guinea pigs (GPs) with electrocorticographic (ECoG) arrays and recorded baseline auditory cortical responses to a startling stimulus. When a gap was inserted in otherwise continuous background noise prior to the startling stimulus, there was a clear reduction in the subsequent evoked response (termed gap-induced reductions in evoked potentials; GIREP), suggestive of a neural analogue of the GPIAS test. We then unilaterally exposed guinea pigs to narrowband noise (left ear; 8-10 kHz; 1 h) at one of two different sound levels - either 105 dB SPL or 120 dB SPL - and recorded the same responses seven-to-ten weeks following the noise exposure. Significant deficits in GIREP were observed for all areas of the auditory cortex (AC) in the 120 dB-exposed GPs, but not in the 105 dB-exposed GPs. These deficits could not simply be accounted for by changes in response amplitudes. Furthermore, in the contralateral (right) caudal AC we observed a significant increase in evoked potential amplitudes across narrowband background frequencies in both 105 dB and 120 dB-exposed GPs. Taken in the context of the large body of literature that has used the behavioural test as a demonstration of the presence of tinnitus, these results are suggestive of objective neural correlates of the presence of noise-induced tinnitus and hyperacusis. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Calcium Sensing Receptors Mediate Local Inhibitory Reflexes Evoked by L-Phenylalanine in Guinea Pig Jejunum.

PubMed

Gwynne, Rachel M; Ly, Kenny D K N; Parry, Laura J; Bornstein, Joel C

2017-01-01

Amino acids applied to the mucosa evoke inhibitory reflexes in guinea-pig jejunum, but the receptors involved in sensory transduction are still unclear. One promising candidate is the extracellular calcium sensing receptor (CaSR), which is expressed by mucosal enteroendocrine cells and is preferentially activated by aromatic L-amino acids. We tested this by applying various amino acids to the mucosa and recording the resulting inhibitory junction potentials (IJPs) in nearby circular smooth muscle via intracellular recording. The CaSR is stereospecific and L-Phenylalanine evoked a significantly larger response than D-Phenylalanine when both were applied to the same site. The same pattern was seen with L- and D-Tryptophan, another aromatic amino acid. The CaSR is preferentially activated by aromatic amino acids and responses to L-Leucine and L-Lysine were significantly lower than those to L-Phenylalanine applied to the same site. Responses to L-Phenylalanine were dose-dependently suppressed by blockade of the CaSR with NPS2143, a CaSR antagonist, and mimicked by mucosal application of cinacalcet, a CaSR agonist. Responses to cinacalcet had similar pharmacology to that of responses to L-Phenylalanine, in that each requires both P2 purinoreceptors and 5-HT receptors. L-Glutamate evoked IJPs similar to those produced by L-Phenylalanine and these were depressed by blockade of P2 receptors and 5-HT 3 plus 5-HT 4 receptors, but NPS2143 was ineffective. The AMPA receptor antagonists DNQX (10 μM) and CNQX (10 μM) reduced IJPs evoked by L-Glutamate by 88 and 79% respectively, but neither BAY367260 (mGluR5 antagonist) nor 2APV (NMDA antagonist) affected IJPs evoked by L-Glutamate. We conclude that local inhibitory reflexes evoked by aromatic L-amino acids in guinea pig jejunum involve activation of CaSRs which triggers release of ATP and 5-HT from the mucosa. L-Glutamate also evokes inhibitory reflexes, via a pathway that does not involve CaSRs. It is likely there are multiple receptors acting as sensory transducers for different luminal amino acids.

Placebo analgesia is not due to compliance or habituation: EEG and behavioural evidence.

PubMed

Watson, Alison; El-Deredy, Wael; Vogt, Brent A; Jones, Anthony K P

2007-05-28

This study was designed to resolve whether experimental placebo responses are due to either increased compliance or habituation. We stimulated both forearms and recorded laser-evoked potentials from 18 healthy volunteers treated on one arm with a sham analgesic cream and an inactive cream on the other (treatment group), and 13 volunteers with an inactive cream on both arms (controls). The treatment group showed a significant reduction in the pain ratings and laser-evoked potentials with both the sham and inactive creams. The control group showed no evidence of habituation to the laser stimulus. The results indicate that the reduction in pain during experimental placebo response is unlikely to be due to sensory habituation or compliance with the experimental instructions.

The effects of click and tone-burst stimulus parameters on the vestibular evoked myogenic potential (VEMP).

PubMed

Akin, Faith Wurm; Murnane, Owen D; Proffitt, Tina M

2003-11-01

Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.

Electrophysiological measurement of human auditory function

NASA Technical Reports Server (NTRS)

Galambos, R.

1975-01-01

Contingent negative variations in the presence and amplitudes of brain potentials evoked by sound are considered. Evidence is produced that the evoked brain stem response to auditory stimuli is clearly related to brain events associated with cognitive processing of acoustic signals since their properties depend upon where the listener directs his attention, whether the signal is an expected event or a surprise, and when sound that is listened-for is heard at last.

GABAergic Neural Activity Involved in Salicylate-Induced Auditory Cortex Gain Enhancement

PubMed Central

Lu, Jianzhong; Lobarinas, Edward; Deng, Anchun; Goodey, Ronald; Stolzberg, Daniel; Salvi, Richard J.; Sun, Wei

2011-01-01

Although high doses of sodium salicylate impair cochlear function, it paradoxically enhances sound-evoked activity in the auditory cortex (AC) and augments acoustic startle reflex responses, neural and behavioral metrics associated with hyperexcitability and hyperacusis. To explore the neural mechanisms underlying salicylate-induced hyperexcitability and “increased central gain”, we examined the effects of γ-aminobutyric acid (GABA) receptor agonists and antagonists on salicylate-induced hyperexcitability in the AC and startle reflex responses. Consistent with our previous findings, local or systemic application of salicylate significantly increased the amplitude of sound-evoked AC neural activity, but generally reduced spontaneous activity in the AC. Systemic injection of salicylate also significantly increased the acoustic startle reflex. S-baclofen or R-baclofen, GABA-B agonists, which suppressed sound-evoked AC neural firing rate and local field potentials, also suppressed the salicylate-induced enhancement of the AC field potential and the acoustic startle reflex. Local application of vigabatrin, which enhances GABA concentration in the brain, suppressed the salicylate-induced enhancement of AC firing rate. Systemic injection of vigabatrin also reduced the salicylate-induced enhancement of acoustic startle reflex. Collectively, these results suggest that the sound-evoked behavioral and neural hyperactivity induced by salicylate may arise from a salicylate-induced suppression GABAergic inhibition in the AC. PMID:21664433

Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study.

PubMed

Leite, Renata Aparecida; Magliaro, Fernanda Cristina Leite; Raimundo, Jeziela Cristina; Bento, Ricardo Ferreira; Matas, Carla Gentile

2018-02-19

The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users.

Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study

PubMed Central

Leite, Renata Aparecida; Magliaro, Fernanda Cristina Leite; Raimundo, Jeziela Cristina; Bento, Ricardo Ferreira; Matas, Carla Gentile

2018-01-01

OBJECTIVE: The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. METHODS: Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. RESULTS: The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. CONCLUSIONS: Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users. PMID:29466495

Auditory- and Vestibular-Evoked Potentials Correlate with Motor and Non-Motor Features of Parkinson’s Disease

PubMed Central

Shalash, Ali Soliman; Hassan, Dalia Mohamed; Elrassas, Hanan Hani; Salama, Mohamed Mosaad; Méndez-Hernández, Edna; Salas-Pacheco, José M.; Arias-Carrión, Oscar

2017-01-01

Degeneration of several brainstem nuclei has been long related to motor and non-motor symptoms (NMSs) of Parkinson’s disease (PD). Nevertheless, due to technical issues, there are only a few studies that correlate that association. Brainstem auditory-evoked potential (BAEP) and vestibular-evoked myogenic potential (VEMP) responses represent a valuable tool for brainstem assessment. Here, we investigated the abnormalities of BAEPs, ocular VEMPs (oVEMPs), and cervical VEMPs (cVEMPs) in patients with PD and its correlation to the motor and NMSs. Fifteen patients diagnosed as idiopathic PD were evaluated by Unified Parkinson’s Disease Rating Scale and its subscores, Hoehn and Yahr scale, Schwab and England scale, and Non-Motor Symptoms Scale. PD patients underwent pure-tone, speech audiometry, tympanometry, BAEP, oVEMPs, and cVEMPs, and compared to 15 age-matched control subjects. PD subjects showed abnormal BAEP wave morphology, prolonged absolute latencies of wave V and I–V interpeak latencies. Absent responses were the marked abnormality seen in oVEMP. Prolonged latencies with reduced amplitudes were seen in cVEMP responses. Rigidity and bradykinesia were correlated to the BAEP and cVEMP responses contralateral to the clinically more affected side. Contralateral and ipsilateral cVEMPs were significantly correlated to sleep (p = 0.03 and 0.001), perception (p = 0.03), memory/cognition (p = 0.025), and urinary scores (p = 0.03). The oVEMP responses showed significant correlations to cardiovascular (p = 0.01) and sexual dysfunctions (p = 0.013). PD is associated with BAEP and VEMP abnormalities that are correlated to the motor and some non-motor clinical characteristics. These abnormalities could be considered as potential electrophysiological biomarkers for brainstem dysfunction and its associated motor and non-motor features. PMID:28289399

Cholesterol-dependent balance between evoked and spontaneous synaptic vesicle recycling

PubMed Central

Wasser, Catherine R; Ertunc, Mert; Liu, Xinran; Kavalali, Ege T

2007-01-01

Cholesterol is a prominent component of nerve terminals. To examine cholesterol's role in central neurotransmission, we treated hippocampal cultures with methyl-β-cyclodextrin, which reversibly binds cholesterol, or mevastatin, an inhibitor of cholesterol biosynthesis, to deplete cholesterol. We also used hippocampal cultures from Niemann-Pick type C1-deficient mice defective in intracellular cholesterol trafficking. These conditions revealed an augmentation in spontaneous neurotransmission detected electrically and an increase in spontaneous vesicle endocytosis judged by horseradish peroxidase uptake after cholesterol depletion by methyl-β-cyclodextrin. In contrast, responses evoked by action potentials and hypertonicity were severely impaired after the same treatments. The increase in spontaneous vesicle recycling and the decrease in evoked neurotransmission were reversible upon cholesterol addition. Cholesterol removal did not impact on the low level of evoked neurotransmission seen in the absence of synaptic vesicle SNARE protein synaptobrevin-2 whereas the increase in spontaneous fusion remained. These results suggest that synaptic cholesterol balances evoked and spontaneous neurotransmission by hindering spontaneous synaptic vesicle turnover and sustaining evoked exo-endocytosis. PMID:17170046

Cortical response variability as a developmental index of selective auditory attention

PubMed Central

Strait, Dana L.; Slater, Jessica; Abecassis, Victor; Kraus, Nina

2014-01-01

Attention induces synchronicity in neuronal firing for the encoding of a given stimulus at the exclusion of others. Recently, we reported decreased variability in scalp-recorded cortical evoked potentials to attended compared with ignored speech in adults. Here we aimed to determine the developmental time course for this neural index of auditory attention. We compared cortical auditory-evoked variability with attention across three age groups: preschoolers, school-aged children and young adults. Results reveal an increased impact of selective auditory attention on cortical response variability with development. Although all three age groups have equivalent response variability to attended speech, only school-aged children and adults have a distinction between attend and ignore conditions. Preschoolers, on the other hand, demonstrate no impact of attention on cortical responses, which we argue reflects the gradual emergence of attention within this age range. Outcomes are interpreted in the context of the behavioral relevance of cortical response variability and its potential to serve as a developmental index of cognitive skill. PMID:24267508

On Why Targets Evoke P3 Components in Prediction Tasks: Drawing an Analogy between Prediction and Matching Tasks

PubMed Central

Verleger, Rolf; Cäsar, Stephanie; Siller, Bastian; Śmigasiewicz, Kamila

2017-01-01

P3 is the most conspicuous component in recordings of stimulus-evoked EEG potentials from the human scalp, occurring whenever some task has to be performed with the stimuli. The process underlying P3 has been assumed to be the updating of expectancies. More recently, P3 has been related to decision processing and to activation of established stimulus-response associations (S/R-link hypothesis). However, so far this latter approach has not provided a conception about how to explain the occurrence of P3 with predicted stimuli, although P3 was originally discovered in a prediction task. The present article proposes such a conception. We assume that the internal responses right or wrong both become associatively linked to each predicted target and that one of these two response alternatives gets activated as a function of match or mismatch of the target to the preceding prediction. This seems similar to comparison tasks where responses depend on the matching of the target stimulus with a preceding first stimulus (S1). Based on this idea, this study compared the effects of frequencies of first events (predictions or S1) on target-evoked P3s in prediction and comparison tasks. Indeed, frequencies not only of targets but also of first events had similar effects across tasks on target-evoked P3s. These results support the notion that P3 evoked by predicted stimuli reflects activation of appropriate internal “match” or “mismatch” responses, which is compatible with S/R-link hypothesis. PMID:29066965

Ocular Vestibular Evoked Myogenic Potentials in Response to Three Test Positions and Two Frequencies

PubMed Central

Todai, Janvi K.; Congdon, Sharon L.; Sangi-Haghpeykar, Haleh; Cohen, Helen S.

2014-01-01

Objective To determine how eye closure, test positions, and stimulus frequencies influence ocular vestibular evoked myogenic potentials. Study Design This study used a within-subjects repeated measures design. Methods Twenty asymptomatic subjects were each tested on ocular vestibular evoked myogenic potentials in three head/eye conditions at 500 Hz and 1000 Hz using air-conducted sound: 1) Sitting upright, head erect, eyes open, looking up. 2) Lying supine, neck flexed 30 degrees, eyes open and looking up. 3) Lying supine, neck flexed 30 degrees, eyes closed and relaxed. Four dependent variables measured were n10, p16, amplitude, and threshold. Results The supine position/ eyes open was comparable to sitting/ eyes open and better than supine/ eyes closed. Eyes closed resulted in lower amplitude, higher threshold, and prolonged latency. Significantly fewer subjects provided responses with eyes closed than with eyes open. No significant differences were found between both eyes open conditions. Both n10 and p16 were lower at 1000 Hz than at 500 Hz. Amplitude and threshold were higher at 1000 Hz than at 500 Hz. Conclusion Supine eyes open is a reliable alternative to sitting eyes open in patients who cannot maintain a seated position. Testing at 1000 Hz provides a larger response with a faster onset that fatigues faster than at 500 Hz. The increased variability and decreased response in the eyes closed position suggest that the eyes closed position is not reliable. PMID:24178911

Calcium Dynamics in Basal Dendrites of Layer 5A and 5B Pyramidal Neurons Is Tuned to the Cell-Type Specific Physiological Action Potential Discharge

PubMed Central

Krieger, Patrik; de Kock, Christiaan P. J.; Frick, Andreas

2017-01-01

Layer 5 (L5) is a major neocortical output layer containing L5A slender-tufted (L5A-st) and L5B thick-tufted (L5B-tt) pyramidal neurons. These neuron types differ in their in vivo firing patterns, connectivity and dendritic morphology amongst other features, reflecting their specific functional role within the neocortical circuits. Here, we asked whether the active properties of the basal dendrites that receive the great majority of synaptic inputs within L5 differ between these two pyramidal neuron classes. To quantify their active properties, we measured the efficacy with which action potential (AP) firing patterns backpropagate along the basal dendrites by measuring the accompanying calcium transients using two-photon laser scanning microscopy in rat somatosensory cortex slices. For these measurements we used both “artificial” three-AP patterns and more complex physiological AP patterns that were previously recorded in anesthetized rats in L5A-st and L5B-tt neurons in response to whisker stimulation. We show that AP patterns with relatively few APs (3APs) evoke a calcium response in L5B-tt, but not L5A-st, that is dependent on the temporal pattern of the three APs. With more complex in vivo recorded AP patterns, the average calcium response was similar in the proximal dendrites but with a decay along dendrites (measured up to 100 μm) of L5B-tt but not L5A-st neurons. Interestingly however, the whisker evoked AP patterns—although very different for the two cell types—evoke similar calcium responses. In conclusion, although the effectiveness with which different AP patterns evoke calcium transients vary between L5A-st and L5B-tt cell, the calcium influx appears to be tuned such that whisker-evoked calcium transients are within the same dynamic range for both cell types. PMID:28744201

Correlation between electrical and hemodynamic responses during visual stimulation with graded contrasts

NASA Astrophysics Data System (ADS)

Si, Juanning; Zhang, Xin; Li, Yuejun; Zhang, Yujin; Zuo, Nianming; Jiang, Tianzi

2016-09-01

Brain functional activity involves complex cellular, metabolic, and vascular chain reactions, making it difficult to comprehend. Electroencephalography (EEG) and functional near infrared spectroscopy (fNIRS) have been combined into a multimodal neuroimaging method that captures both electrophysiological and hemodynamic information to explore the spatiotemporal characteristics of brain activity. Because of the significance of visually evoked functional activity in clinical applications, numerous studies have explored the amplitude of the visual evoked potential (VEP) to clarify its relationship with the hemodynamic response. However, relatively few studies have investigated the influence of latency, which has been frequently used to diagnose visual diseases, on the hemodynamic response. Moreover, because the latency and the amplitude of VEPs have different roles in coding visual information, investigating the relationship between latency and the hemodynamic response should be helpful. In this study, checkerboard reversal tasks with graded contrasts were used to evoke visual functional activity. Both EEG and fNIRS were employed to investigate the relationship between neuronal electrophysiological activities and the hemodynamic responses. The VEP amplitudes were linearly correlated with the hemodynamic response, but the VEP latency showed a negative linear correlation with the hemodynamic response.

A simple model for the generation of the vestibular evoked myogenic potential (VEMP).

PubMed

Wit, Hero P; Kingma, Charlotte M

2006-06-01

To describe the mechanism by which the vestibular evoked myogenic potential is generated. Vestibular evoked myogenic potential generation is modeled by adding a large number of muscle motor unit action potentials. These action potentials occur randomly in time along a 100 ms long time axis. But because between approximately 15 and 20 ms after a loud short sound stimulus (almost) no action potentials are generated during VEMP measurements in human subjects, no action potentials are present in the model during this time. The evoked potential is the result of the lack of amplitude cancellation in the averaged surface electromyogram at the edges of this 5 ms long time interval. The relatively simple model describes generation and some properties of the vestibular evoked myogenic potential very well. It is shown that, in contrast with other evoked potentials (BAEPs, VERs), the vestibular evoked myogenic potential is the result of an interruption of activity and not that of summed synchronized neural action potentials.

Submillisecond unmasked subliminal visual stimuli evoke electrical brain responses.

PubMed

Sperdin, Holger F; Spierer, Lucas; Becker, Robert; Michel, Christoph M; Landis, Theodor

2015-04-01

Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256-channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio-temporal dynamics of the brain response to visual checkerboard stimuli (Experiment 1) or blank stimuli (Experiment 2) presented without a mask for 1 ms (visible), 500 µs (partially visible), and 250 µs (subliminal) by applying time-wise, assumption-free nonparametric randomization statistics on the strength and on the topography of high-density scalp-recorded electric field. Stimulus visibility was assessed in a third separate behavioral experiment. Results revealed that unmasked checkerboards presented subliminally for 250 µs evoked weak but detectable visual evoked potential (VEP) responses. When the checkerboards were replaced by blank stimuli, there was no evidence for the presence of an evoked response anymore. Furthermore, the checkerboard VEPs were modulated topographically between 243 and 296 ms post-stimulus onset as a function of stimulus duration, indicative of the engagement of distinct configuration of active brain networks. A distributed electrical source analysis localized this modulation within the right superior parietal lobule near the precuneus. These results show the presence of a brain response to submillisecond unmasked subliminal visual stimuli independently of their emotional saliency or meaningfulness and opens an avenue for new investigations of subliminal stimulation without using visual masking. © 2014 Wiley Periodicals, Inc.

Are evoked potentials in patients with adult-onset pompe disease indicative of clinically relevant central nervous system involvement?

PubMed

Wirsching, Andreas; Müller-Felber, Wolfgang; Schoser, Benedikt

2014-08-01

Pompe disease is a multisystem autosomal recessive glycogen storage disease. Autoptic findings in patients with classic infantile and late-onset Pompe disease have proven that accumulation of glycogen can also be found in the peripheral and central nervous system. To assess the functional role of these pathologic findings, multimodal sensory evoked potentials were analyzed. Serial recordings for brainstem auditory, visual, and somatosensory evoked potentials of 11 late-onset Pompe patients were reviewed. Data at the onset of the enzyme replacement therapy with alglucosidase alfa were compared with follow-up recordings at 12 and 24 months. Brainstem auditory evoked potentials showed a delayed peak I in 1/10 patients and an increased I-III and I-V interpeak latency in 1/10 patients, respectively. The III-V interpeak latencies were in the normal range. Visual evoked potentials were completely normal. Median somatosensory evoked potentials showed an extended interpeak latency in 3/9 patients. Wilcoxon tests comparing age-matched subgroups found significant differences in brainstem auditory evoked potentials and visual evoked potentials. We found that the majority of recordings for evoked potentials were within the ranges for standard values, therefore reflecting the lack of clinically relevant central nervous system involvement. Regular surveillance by means of evoked potentials does not seem to be appropriate in late-onset Pompe patients.

Cervical Vestibular-Evoked Myogenic Potentials: Norms and Protocols

PubMed Central

Isaradisaikul, Suwicha; Navacharoen, Niramon; Hanprasertpong, Charuk; Kangsanarak, Jaran

2012-01-01

Vestibular-evoked myogenic potential (VEMP) testing is a vestibular function test used for evaluating saccular and inferior vestibular nerve function. Parameters of VEMP testing include VEMP threshold, latencies of p1 and n1, and p1-n1 interamplitude. Less commonly used parameters were p1-n1 interlatency, interaural difference of p1 and n1 latency, and interaural amplitude difference (IAD) ratio. This paper recommends using air-conducted 500 Hz tone burst auditory stimulation presented monoaurally via an inserted ear phone while the subject is turning his head to the contralateral side in the sitting position and recording the responses from the ipsilateral sternocleidomastoid muscle. Normative values of VEMP responses in 50 normal audiovestibular volunteers were presented. VEMP testing protocols and normative values in other literature were reviewed and compared. The study is beneficial to clinicians as a reference guide to set up VEMP testing and interpretation of the VEMP responses. PMID:22577386

Mid-latency auditory evoked potential response revealed as an evidence of neural plasticity in blinnd individuals.

PubMed

Muthusamy, Anbarasi; Gajendran, Rajkumar; Rao B, Vishwanatha

2014-01-01

There is a general impression that visually blind individuals show an exceptionally better perception of other sensory modalities such as hearing, touch and smell sensations. In this study, we intended to compare the mid-latency auditory evoked potential response (MLAEP) or Middle latency Response (MLR) to get an idea of the activity pattern of auditory thalamus and cortex between 30 visually handicapped subjects and 30 normal sighted subjects. The results showed a decrease in many of the MLR wave latencies, but highly significant for the wave Pa (P value <0.002). This fact can be reflected as an evidence of existence of cross-modal neuroplasticity. We also inferred that there are significant gender differences with latencies shorter in males than females (P value <0.02) in the blind subjects group which could be attributed to their rehabilitation training.

Cerebellar interaction with the acoustic reflex.

PubMed

Jastreboff, P J

1981-01-01

The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

Ocular vestibular evoked myogenic potentials elicited with vibration applied to the teeth.

PubMed

Parker-George, Jennifer C; Bell, Steven L; Griffin, Michael J

2016-01-01

This study investigated whether the method for eliciting vibration-induced oVEMPs could be improved by applying vibration directly to the teeth, and how vibration-induced oVEMP responses depend on the duration of the applied vibration. In 10 participants, a hand-held shaker was used to present 100-Hz vibration tone pips to the teeth via a customised bite-bar or to other parts of the head. oVEMP potentials were recorded in response to vibration in three orthogonal directions and five stimulus durations (10-180 ms). The oVEMP responses were analysed in terms of the peak latency onset, peak-to-peak amplitude, and the quality of the trace. Vibration applied to the teeth via the bite-bar produced oVEMPs that were more consistent, of higher quality and of greater amplitude than those evoked by vibration applied to the head. Longer duration stimuli produced longer duration oVEMP responses. One cycle duration stimuli produced responses that were smaller in amplitude and lower quality than the longer stimulus durations. Application of vibration via the teeth using a bite-bar is an effective means of producing oVEMPs. A 1-cycle stimulus is not optimal to evoke an oVEMP because it produces less robust responses than those of longer stimulus duration. A positive relationship between the duration of the stimulus and the response is consistent with the notion that the vibration-induced oVEMP is an oscillatory response to the motion of the head, rather than being a simple reflex response that occurs when the stimulus exceeds a threshold level of stimulation. Applying acceleration to the teeth through a bite-bar elicits clearer oVEMP responses than direct application to other parts of the head and has potential to improve clinical measurements. A 100-Hz 1-cycle stimulus produces less robust oVEMP responses than longer 100-Hz stimuli. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Visual evoked potentials in patients after methanol poisoning.

PubMed

Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

2016-01-01

We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Brainstem auditory-evoked potentials as an objective tool for evaluating hearing dysfunction in traumatic brain injury.

PubMed

Lew, Henry L; Lee, Eun Ha; Miyoshi, Yasushi; Chang, Douglas G; Date, Elaine S; Jerger, James F

2004-03-01

Because of the violent nature of traumatic brain injury, traumatic brain injury patients are susceptible to various types of trauma involving the auditory system. We report a case of a 55-yr-old man who presented with communication problems after traumatic brain injury. Initial results from behavioral audiometry and Weber/Rinne tests were not reliable because of poor cooperation. He was transferred to our service for inpatient rehabilitation, where review of the initial head computed tomographic scan showed only left temporal bone fracture. Brainstem auditory-evoked potential was then performed to evaluate his hearing function. The results showed bilateral absence of auditory-evoked responses, which strongly suggested bilateral deafness. This finding led to a follow-up computed tomographic scan, with focus on bilateral temporal bones. A subtle transverse fracture of the right temporal bone was then detected, in addition to the left temporal bone fracture previously identified. Like children with hearing impairment, traumatic brain injury patients may not be able to verbalize their auditory deficits in a timely manner. If hearing loss is suspected in a patient who is unable to participate in traditional behavioral audiometric testing, brainstem auditory-evoked potential may be an option for evaluating hearing dysfunction.

The evaluation of the novel pressor activity of gamma-piperidinobutyramide (WY 20051, DF480).

PubMed Central

Alps, B J; Devoy, P W; Waterfall, J F

1976-01-01

1 gamma-Piperidinobutyramide (Wy 20051, DF480) injected intravenously evoked pressor responses in the anaesthetized ganglion blocked rat preparation over the dose range 2.4 x 10(-6)-3.0 x 10(-4) mol/kg. 2 High doses (greater than 3.8 x 10(-5) mol/kg) or even repeated submaximal doses (1.9 x 10(-5) mol/kg) of Wy 20051 caused tachyphylaxis of this pressor response. 3 The noradrenaline pressor-response curve was shifted significantly to the right of the control curve following a dose of Wy 20051 (1.5 x 10(-4) mol/kg cumulative). 4 The dose-response curve for the pressor action of Wy 20051 was potentiated in reserpine-treated anaesthetized rats. In contrast, tyramine-induced pressor responses were abolished. 5 Wy 20051 contracted the guinea-pig isolated aortic spiral preparation (3.8 x 10(-5)-6.0 x 10(-4) mol) and evoked constrictor responses in the perfused mesenteric vasculature preparation of the rat (5.9 x 10(-7)-1.2 x 10(-5) mol). At higher doses the responses were reduced. 6 Wy 20051-induced constrictor responses of the perfused mesentery were unaffected by blockade of alpha-adrenoceptors or by tachyphylaxis of 5-hydroxytryptamine receptors. 7 The time for abolition of Wy 20051-induced constrictor responses of the mesentery in a calcium-free medium was not significantly different from that required for noradrenaline, but was significantly greater than that for KCl (P less than 0.001). 8 Wy 20051 and noradrenaline, but not KCl, evoked constrictor responses in the depolarized rat mesenteric vasculature. 9 The results indicate that Wy 20051 evokes pressor responses which have some of the characteristics of those of noradrenaline. However, the responses are not elicited by an alpha-adrenoceptor mechanism. PMID:3247

High-frequency combination coding-based steady-state visual evoked potential for brain computer interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Feng; Zhang, Xin; Xie, Jun

2015-03-10

This study presents a new steady-state visual evoked potential (SSVEP) paradigm for brain computer interface (BCI) systems. The goal of this study is to increase the number of targets using fewer stimulation high frequencies, with diminishing subject’s fatigue and reducing the risk of photosensitive epileptic seizures. The new paradigm is High-Frequency Combination Coding-Based High-Frequency Steady-State Visual Evoked Potential (HFCC-SSVEP).Firstly, we studied SSVEP high frequency(beyond 25 Hz)response of SSVEP, whose paradigm is presented on the LED. The SNR (Signal to Noise Ratio) of high frequency(beyond 40 Hz) response is very low, which is been unable to be distinguished through the traditional analysis method;more » Secondly we investigated the HFCC-SSVEP response (beyond 25 Hz) for 3 frequencies (25Hz, 33.33Hz, and 40Hz), HFCC-SSVEP produces n{sup n} with n high stimulation frequencies through Frequence Combination Code. Further, Animproved Hilbert-huang transform (IHHT)-based variable frequency EEG feature extraction method and a local spectrum extreme target identification algorithmare adopted to extract time-frequency feature of the proposed HFCC-SSVEP response.Linear predictions and fixed sifting (iterating) 10 time is used to overcome the shortage of end effect and stopping criterion,generalized zero-crossing (GZC) is used to compute the instantaneous frequency of the proposed SSVEP respondent signals, the improved HHT-based feature extraction method for the proposed SSVEP paradigm in this study increases recognition efficiency, so as to improve ITR and to increase the stability of the BCI system. what is more, SSVEPs evoked by high-frequency stimuli (beyond 25Hz) minimally diminish subject’s fatigue and prevent safety hazards linked to photo-induced epileptic seizures, So as to ensure the system efficiency and undamaging.This study tests three subjects in order to verify the feasibility of the proposed method.« less

The TRPV1 channel in rodents is a major target for antinociceptive effect of the probiotic Lactobacillus reuteri DSM 17938

PubMed Central

Perez-Burgos, Azucena; Wang, Lu; McVey Neufeld, Karen-Anne; Mao, Yu-Kang; Ahmadzai, Mustafa; Janssen, Luke J; Stanisz, Andrew M; Bienenstock, John; Kunze, Wolfgang A

2015-01-01

Abstract Certain bacteria exert visceral antinociceptive activity, but the mechanisms involved are not determined. Lactobacillus reuteri DSM 17938 was examined since it may be antinociceptive in children. Since transient receptor potential vanilloid 1 (TRPV1) channel activity may mediate nociceptive signals, we hypothesized that TRPV1 current is inhibited by DSM. We tested this by examining the effect of DSM on the firing frequency of spinal nerve fibres in murine jejunal mesenteric nerve bundles following serosal application of capsaicin. We also measured the effects of DSM on capsaicin-evoked increase in intracellular Ca2+ or ionic current in dorsal root ganglion (DRG) neurons. Furthermore, we tested the in vivo antinociceptive effects of oral DSM on gastric distension in rats. Live DSM reduced the response of capsaicin- and distension-evoked firing of spinal nerve action potentials (238 ± 27.5% vs. 129 ± 17%). DSM also reduced the capsaicin-evoked TRPV1 ionic current in DRG neuronal primary culture from 83 ± 11% to 41 ± 8% of the initial response to capsaicin only. Another lactobacillus (Lactobacillus rhamnosus JB-1) with known visceral anti-nociceptive activity did not have these effects. DSM also inhibited capsaicin-evoked Ca2+ increase in DRG neurons; an increase in Ca2+ fluorescence intensity ratio of 2.36 ± 0.31 evoked by capsaicin was reduced to 1.25 ± 0.04. DSM releasable products (conditioned medium) mimicked DSM inhibition of capsaicin-evoked excitability. The TRPV1 antagonist 6-iodonordihydrocapsaicin or the use of TRPV1 knock-out mice revealed that TRPV1 channels mediate about 80% of the inhibitory effect of DSM on mesenteric nerve response to high intensity gut distension. Finally, feeding with DSM inhibited perception in rats of painful gastric distension. Our results identify a specific target channel for a probiotic with potential therapeutic properties. Key points Certain probiotic bacteria have been shown to reduce distension-dependent gut pain, but the mechanisms involved remain obscure. Live luminal Lactobacillus reuteri (DSM 17938) and its conditioned medium dose dependently reduced jejunal spinal nerve firing evoked by distension or capsaicin, and 80% of this response was blocked by a specific TRPV1 channel antagonist or in TRPV1 knockout mice. The specificity of DSM action on TRPV1 was further confirmed by its inhibition of capsaicin-induced intracellular calcium increases in dorsal root ganglion neurons. Another lactobacillus with ability to reduce gut pain did not modify this response. Prior feeding of rats with DSM inhibited the bradycardia induced by painful gastric distension. These results offer a system for the screening of new and improved candidate bacteria that may be useful as novel therapeutic adjuncts in gut pain. PMID:26084409

Effects of high-level pulse train stimulation on retinal function.

PubMed

Cohen, Ethan D

2009-06-01

We examined how stimulation of the local retina by high-level current pulse trains affected the light-evoked responses of the retinal ganglion cells. The spikes of retinal ganglion cell axons were recorded extracellularly using an in vitro eyecup preparation of the rabbit retina. Epiretinal electrical stimulation was delivered via a 500 microm inner diameter saline-filled, transparent tube positioned over the retinal surface forming the receptive field center. Spot stimuli were presented periodically to the receptive field center during the experiment. Trains of biphasic 1 ms current pulses were delivered to the retina at 50 Hz for 1 min. Pulse train charge densities of 1.3-442 microC/cm(2)/phase were examined. After pulse train stimulation with currents >or=300 microA (133 microC/cm(2)/phase), the ganglion cell's ability to respond to light was depressed and a significant time was required for recovery of the light-evoked response. During train stimulation, the ganglion cell's ability to spike following each current pulse fatigued. The current levels evoking train-evoked depression were suprathreshold to those evoking action potentials. Train-evoked depression was stronger touching the retinal surface, and in some cases impaired ganglion cell function for up to 30 min. This overstimulation could cause a transient refractory period for electrically stimulated perception in the retinal region below the electrode.

Hierarchical equivalence of somatosensory areas I and II for tactile processing in the cerebral cortex of the marmoset monkey.

PubMed

Zhang, H Q; Zachariah, M K; Coleman, G T; Rowe, M J

2001-05-01

Responsiveness of the first somatosensory area (SI) of the cerebral cortex was investigated in the marmoset monkey (Callithrix jacchus) in association with cooling-induced, reversible inactivation of the second somatosensory area, SII. The aim was to determine whether SI responsiveness to peripheral tactile stimulation depends on SII and therefore whether SI and SII in the marmoset occupy hierarchically equivalent positions in a parallel organizational scheme for thalamocortical tactile processing as appears to be the case in nonprimate mammals. Inactivation of SII was achieved when the temperature over SII was lowered to < or =12 degrees C, as indicated by abolition of the SII-evoked potentials generated by brief tap stimuli to the hand or foot, and by abolition of tactile responses in single SII neurons located at the margin beneath the block. The effect of SII inactivation on SI-evoked potentials was examined in 16 experiments by simultaneous recording of the SI- and SII-evoked potentials. SI-evoked potentials were never abolished and remained unaffected in 11 cases. In three experiments there was a small reduction in amplitude and inconsistent effects in the remaining two. Responsiveness to controlled tactile stimuli was examined quantitatively in 31 individual SI neurons of different functional classes before, during, and after the inactivation of SII. Tactile responsiveness in individual SI neurons was never abolished by SII inactivation, remaining unchanged in 20 neurons (65%) while undergoing some reduction in the remaining 11 SI neurons (35%). This reduction of tactile responsiveness in one-third of SI neurons is most likely attributable to a removal of a facilitatory influence emanating from SII, based on the observation that background activity of the affected neurons was also reduced. Furthermore, phase locking of SI responses to vibrotactile stimulation was unchanged when SII was inactivated. The retention of responsiveness in SI neurons when SII was inactivated by cooling in the marmoset demonstrates that tactile inputs can reach SI without traversing an indirect, serially organized path through SII. The present results, together with our previous observations that responsiveness in the majority of SII neurons survived SI inactivation, demonstrate that there is a parallel organization of the SI and SII areas for tactile processing in the marmoset monkey and that SI and SII occupy hierarchically equivalent positions in a parallel processing network. There is therefore no longer justification for the view that there are fundamental differences in the organization of thalamocortical tactile processing for SI and SII between simian primates, in general, and other mammals.

Electroretinography and Visual Evoked Potentials in Childhood Brain Tumor Survivors.

PubMed

Pietilä, Sari; Lenko, Hanna L; Oja, Sakari; Koivisto, Anna-Maija; Pietilä, Timo; Mäkipernaa, Anne

2016-07-01

This population-based cross-sectional study evaluates the clinical value of electroretinography and visual evoked potentials in childhood brain tumor survivors. A flash electroretinography and a checkerboard reversal pattern visual evoked potential (or alternatively a flash visual evoked potential) were done for 51 survivors (age 3.8-28.7 years) after a mean follow-up time of 7.6 (1.5-15.1) years. Abnormal electroretinography was obtained in 1 case, bilaterally delayed abnormal visual evoked potentials in 22/51 (43%) cases. Nine of 25 patients with infratentorial tumor location, and altogether 12 out of 31 (39%) patients who did not have tumors involving the visual pathways, had abnormal visual evoked potentials. Abnormal electroretinographies are rarely observed, but abnormal visual evoked potentials are common even without evident anatomic lesions in the visual pathway. Bilateral changes suggest a general and possibly multifactorial toxic/adverse effect on the visual pathway. Electroretinography and visual evoked potential may have clinical and scientific value while evaluating long-term effects of childhood brain tumors and tumor treatment. © The Author(s) 2016.

Loss of lower limb motor evoked potentials and spinal cord injury during the initial exposure in scoliosis surgery.

PubMed

Legatt, Alan D; Fried, Stephen J; Amaral, Terry D; Sarwahi, Vishal; Moguilevitch, Marina

2014-04-01

To report a case of motor evoked potential changes and spinal cord injury during the initial dissection in scoliosis surgery. Motor evoked potentials to transcranial electrical stimulation were recorded from multiple muscles. Somatosensory evoked potentials to limb nerve stimulation were recorded from the scalp. Clear motor evoked potentials were initially present in all monitored muscles. The patient was then pharmacologically paralyzed for the initial dissection. More than usual bleeding was encountered during that dissection, prompting transfusion. As the neuromuscular blockade subsided, motor evoked potentials persisted in the hand muscles but disappeared and remained absent in all monitored leg muscles. The spine had not been instrumented. A wake-up test demonstrated paraplegia; the surgery was aborted. There were no adverse somatosensory evoked potential changes. MRI showed an anterior spinal cord infarct. Copious soft tissue bleeding during the initial dissection might have lowered pressures in critical segmental arteries enough to cause spinal cord infarction through a steal phenomenon. The lack of somatosensory evoked potential changes reflected sparing of the dorsal columns. When neuromuscular blockade is used during the initial soft tissue dissection, motor evoked potentials should be assessed after this, but before spinal instrumentation, to determine whether there had been any spinal cord compromise during the initial dissection.

Patch-clamp analysis of voltage-activated and chemically activated currents in the vomeronasal organ of Sternotherus odoratus (stinkpot/musk turtle)

PubMed Central

Fadool, D. A.; Wachowiak, M.; Brann, J. H.

2011-01-01

Summary The electrophysiological basis of chemical communication in the specialized olfactory division of the vomeronasal (VN) organ is poorly understood. In total, 198 patch-clamp recordings were made from 42 animals (Sternotherus odoratus, the stinkpot/musk turtle) to study the electrically and chemically activated properties of VN neurons. The introduction of tetramethylrhodamine-conjugated dextran into the VN orifice permitted good visualization of the vomeronasal neural epithelium prior to dissociating it into single neurons. Basic electrical properties of the neurons were measured (resting potential, −54.5±2.7 mV, N=11; input resistance, 6.7±1.4GΩ, N=25; capacitance, 4.2±0.3 pF, N=22; means ± S.E.M.). The voltage-gated K+ current inactivation rate was significantly slower in VN neurons from males than in those from females, and K+ currents in males were less sensitive (greater Ki) to tetraethylammonium. Vomeronasal neurons were held at a holding potential of −60 mV and tested for their response to five natural chemicals, female urine, male urine, female musk, male musk and catfish extract. Of the 90 VN neurons tested, 33 (34 %) responded to at least one of the five compounds. The peak amplitude of chemically evoked currents ranged from 4 to 180 pA, with two-thirds of responses less than 25 pA. Urine-evoked currents were of either polarity, whereas musk and catfish extract always elicited only inward currents. Urine applied to neurons harvested from female animals evoked currents that were 2–3 times larger than those elicited from male neurons. Musk-evoked inward currents were three times the magnitude of urine-or catfish-extract-evoked inward currents. The calculated breadth of responsiveness for neurons presented with this array of five chemicals indicated that the mean response spectrum of the VN neurons is narrow (H metric 0.11). This patch-clamp study indicates that VN neurons exhibit sexual dimorphism in function and specificity in response to complex natural chemicals. PMID:11815645

Patch-clamp analysis of voltage-activated and chemically activated currents in the vomeronasal organ of Sternotherus odoratus (stinkpot/musk turtle).

PubMed

Fadool, D A; Wachowiak, M; Brann, J H

2001-12-01

The electrophysiological basis of chemical communication in the specialized olfactory division of the vomeronasal (VN) organ is poorly understood. In total, 198 patch-clamp recordings were made from 42 animals (Sternotherus odoratus, the stinkpot/musk turtle) to study the electrically and chemically activated properties of VN neurons. The introduction of tetramethylrhodamine-conjugated dextran into the VN orifice permitted good visualization of the vomeronasal neural epithelium prior to dissociating it into single neurons. Basic electrical properties of the neurons were measured (resting potential, -54.5 +/- 2.7 mV, N=11; input resistance, 6.7 +/- 1.4 G Omega, N=25; capacitance, 4.2 +/- 0.3 pF, N=22; means +/- S.E.M.). The voltage-gated K(+) current inactivation rate was significantly slower in VN neurons from males than in those from females, and K(+) currents in males were less sensitive (greater K(i)) to tetraethylammonium. Vomeronasal neurons were held at a holding potential of -60 mV and tested for their response to five natural chemicals, female urine, male urine, female musk, male musk and catfish extract. Of the 90 VN neurons tested, 33 (34 %) responded to at least one of the five compounds. The peak amplitude of chemically evoked currents ranged from 4 to 180 pA, with two-thirds of responses less than 25 pA. Urine-evoked currents were of either polarity, whereas musk and catfish extract always elicited only inward currents. Urine applied to neurons harvested from female animals evoked currents that were 2-3 times larger than those elicited from male neurons. Musk-evoked inward currents were three times the magnitude of urine- or catfish-extract-evoked inward currents. The calculated breadth of responsiveness for neurons presented with this array of five chemicals indicated that the mean response spectrum of the VN neurons is narrow (H metric 0.11). This patch-clamp study indicates that VN neurons exhibit sexual dimorphism in function and specificity in response to complex natural chemicals.iol

Evidence that ATP acts at two sites to evoke contraction in the rat isolated tail artery.

PubMed

McLaren, G J; Burke, K S; Buchanan, K J; Sneddon, P; Kennedy, C

1998-05-01

1. The site(s) at which P2-receptor agonists act to evoke contractions of the rat isolated tail artery was studied by use of P2-receptor antagonists and the extracellular ATPase inhibitor 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP (ARL 67156). 2. Suramin (1 microM(-1) mM) and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) (0.3-300 microM) inhibited contractions evoked by equi-effective concentrations of alpha,beta-methyleneATP (alpha,beta-meATP) (5 microM), 2-methylthioATP (2-meSATP) (100 microM) and adenosine 5'-triphosphate (ATP) (1 mM) in a concentration-dependent manner. Responses to alpha,beta-meATP and 2-meSATP were abolished, but approximately one third of the peak response to ATP was resistant to suramin and PPADS. 3. Contractions evoked by uridine 5'-triphosphate (UTP) (1 mM) were slightly inhibited by suramin (100 and 300 microM) and potentiated by PPADS (300 microM). 4. Desensitization of the P2X1-receptor by alpha,beta-meATP abolished contractions evoked by 2-meSATP (100 microM) and reduced those to ATP (1 mM) and UTP (1 mM) to 15+/-3% and 68+/-4% of control. 5. Responses to alpha,beta-meATP (5 microM) and 2-meSATP (100 microM) were abolished when tissues were bathed in nominally calcium-free solution, while the peak contractions to ATP (1 mM) and UTP (1 mM) were reduced to 24+/-6% and 61+/-13%, respectively, of their control response. 6. ARL 67156 (3-100 microM) potentiated contractions elicited by UTP (1 mM), but inhibited responses to alpha,beta-meATP (5 microM), 2-meSATP (100 microM) and ATP (1 mM) in a concentration-dependent manner. 7. These results suggest that two populations of P2-receptors are present in the rat tail artery; ligand-gated P2X1-receptors and G-protein-coupled P2Y-receptors.

A novel method for extraction of neural response from single channel cochlear implant auditory evoked potentials.

PubMed

Sinkiewicz, Daniel; Friesen, Lendra; Ghoraani, Behnaz

2017-02-01

Cortical auditory evoked potentials (CAEP) are used to evaluate cochlear implant (CI) patient auditory pathways, but the CI device produces an electrical artifact, which obscures the relevant information in the neural response. Currently there are multiple methods, which attempt to recover the neural response from the contaminated CAEP, but there is no gold standard, which can quantitatively confirm the effectiveness of these methods. To address this crucial shortcoming, we develop a wavelet-based method to quantify the amount of artifact energy in the neural response. In addition, a novel technique for extracting the neural response from single channel CAEPs is proposed. The new method uses matching pursuit (MP) based feature extraction to represent the contaminated CAEP in a feature space, and support vector machines (SVM) to classify the components as normal hearing (NH) or artifact. The NH components are combined to recover the neural response without artifact energy, as verified using the evaluation tool. Although it needs some further evaluation, this approach is a promising method of electrical artifact removal from CAEPs. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Speech Evoked Auditory Brainstem Response in Stuttering

PubMed Central

Tahaei, Ali Akbar; Ashayeri, Hassan; Pourbakht, Akram; Kamali, Mohammad

2014-01-01

Auditory processing deficits have been hypothesized as an underlying mechanism for stuttering. Previous studies have demonstrated abnormal responses in subjects with persistent developmental stuttering (PDS) at the higher level of the central auditory system using speech stimuli. Recently, the potential usefulness of speech evoked auditory brainstem responses in central auditory processing disorders has been emphasized. The current study used the speech evoked ABR to investigate the hypothesis that subjects with PDS have specific auditory perceptual dysfunction. Objectives. To determine whether brainstem responses to speech stimuli differ between PDS subjects and normal fluent speakers. Methods. Twenty-five subjects with PDS participated in this study. The speech-ABRs were elicited by the 5-formant synthesized syllable/da/, with duration of 40 ms. Results. There were significant group differences for the onset and offset transient peaks. Subjects with PDS had longer latencies for the onset and offset peaks relative to the control group. Conclusions. Subjects with PDS showed a deficient neural timing in the early stages of the auditory pathway consistent with temporal processing deficits and their abnormal timing may underlie to their disfluency. PMID:25215262

A comparative study on long-term evoked auditory and visual potential responses between Schizophrenic patients and normal subjects

PubMed Central

2011-01-01

Background The electrical signals measuring method is recommended to examine the relationship between neuronal activities and measure with the event related potentials (ERPs) during an auditory and a visual oddball paradigm between schizophrenic patients and normal subjects. The aim of this study is to discriminate the activation changes of different stimulations evoked by auditory and visual ERPs between schizophrenic patients and normal subjects. Methods Forty-three schizophrenic patients were selected as experimental group patients, and 40 healthy subjects with no medical history of any kind of psychiatric diseases, neurological diseases, or drug abuse, were recruited as a control group. Auditory and visual ERPs were studied with an oddball paradigm. All the data were analyzed by SPSS statistical software version 10.0. Results In the comparative study of auditory and visual ERPs between the schizophrenic and healthy patients, P300 amplitude at Fz, Cz, and Pz and N100, N200, and P200 latencies at Fz, Cz, and Pz were shown significantly different. The cognitive processing reflected by the auditory and the visual P300 latency to rare target stimuli was probably an indicator of the cognitive function in schizophrenic patients. Conclusions This study shows the methodology of application of auditory and visual oddball paradigm identifies task-relevant sources of activity and allows separation of regions that have different response properties. Our study indicates that there may be slowness of automatic cognitive processing and controlled cognitive processing of visual ERPs compared to auditory ERPs in schizophrenic patients. The activation changes of visual evoked potentials are more regionally specific than auditory evoked potentials. PMID:21542917

Changes in visual-evoked potential habituation induced by hyperventilation in migraine.

PubMed

Coppola, Gianluca; Currà, Antonio; Sava, Simona Liliana; Alibardi, Alessia; Parisi, Vincenzo; Pierelli, Francesco; Schoenen, Jean

2010-12-01

Hyperventilation is often associated with stress, an established trigger factor for migraine. Between attacks, migraine is associated with a deficit in habituation to visual-evoked potentials (VEP) that worsens just before the attack. Hyperventilation slows electroencephalographic (EEG) activity and decreases the functional response in the occipital cortex during visual stimulation. The neural mechanisms underlying deficient-evoked potential habituation in migraineurs remain unclear. To find out whether hyperventilation alters VEP habituation, we recorded VEPs before and after experimentally induced hyperventilation lasting 3 min in 18 healthy subjects and 18 migraine patients between attacks. We measured VEP P100 amplitudes in six sequential blocks of 100 sweeps and habituation as the change in amplitude over the six blocks. In healthy subjects, hyperventilation decreased VEP amplitude in block 1 and abolished the normal VEP habituation. In migraine patients, hyperventilation further decreased the already low block 1 amplitude and worsened the interictal habituation deficit. Hyperventilation worsens the habituation deficit in migraineurs possibly by increasing dysrhythmia in the brainstem-thalamo-cortical network.

Vascular Compliance Limits during Sleep Deprivation and Recovery Sleep

PubMed Central

Phillips, Derrick J.; Schei, Jennifer L.; Rector, David M.

2013-01-01

Study Objectives: Our previous studies showed that evoked hemodynamic responses are smaller during wake compared to sleep; suggesting neural activity is associated with vascular expansion and decreased compliance. We explored whether prolonged activity during sleep deprivation may exacerbate vascular expansion and blunt hemodynamic responses. Design: Evoked auditory responses were generated with periodic 65dB speaker clicks over a 72-h period and measured with cortical electrodes. Evoked hemodynamic responses were measured simultaneously with optical techniques using three light-emitting diodes, and a photodiode. Setting: Animals were housed in separate 30×30×80cm enclosures, tethered to a commutator system and maintained on a 12-h light/dark cycle. Food and water were available ad libitum. Patients or Participants: Seven adult female Sprague-Dawley rats. Interventions: Following a 24-h baseline recording, sleep deprivation was initiated for 0 to 10 h by gentle handling, followed by a 24-h recovery sleep recording. Evoked electrical and hemodynamic responses were measured before, during, and after sleep deprivation. Measurements and Results: Following deprivation, evoked hemodynamic amplitudes were blunted. Steady-state oxyhemoglobin concentration increased during deprivation and remained high during the initial recovery period before returning to baseline levels after approximately 9-h. Conclusions: Sleep deprivation resulted in blood vessel expansion and decreased compliance while lower basal neural activity during recovery sleep may allow blood vessel compliance to recover. Chronic sleep restriction or sleep deprivation could push the vasculature to critical levels, limiting blood delivery, and leading to metabolic deficits with the potential for neural trauma. Citation: Phillips DJ; Schei JL; Rector DM. Vascular compliance limits during sleep deprivation and recovery sleep. SLEEP 2013;36(10):1459-1470. PMID:24082305

Cortical membrane potential signature of optimal states for sensory signal detection

PubMed Central

McGinley, Matthew J.; David, Stephen V.; McCormick, David A.

2015-01-01

The neural correlates of optimal states for signal detection task performance are largely unknown. One hypothesis holds that optimal states exhibit tonically depolarized cortical neurons with enhanced spiking activity, such as occur during movement. We recorded membrane potentials of auditory cortical neurons in mice trained on a challenging tone-in-noise detection task while assessing arousal with simultaneous pupillometry and hippocampal recordings. Arousal measures accurately predicted multiple modes of membrane potential activity, including: rhythmic slow oscillations at low arousal, stable hyperpolarization at intermediate arousal, and depolarization during phasic or tonic periods of hyper-arousal. Walking always occurred during hyper-arousal. Optimal signal detection behavior and sound-evoked responses, at both sub-threshold and spiking levels, occurred at intermediate arousal when pre-decision membrane potentials were stably hyperpolarized. These results reveal a cortical physiological signature of the classically-observed inverted-U relationship between task performance and arousal, and that optimal detection exhibits enhanced sensory-evoked responses and reduced background synaptic activity. PMID:26074005

Human auditory steady state responses to binaural and monaural beats.

PubMed

Schwarz, D W F; Taylor, P

2005-03-01

Binaural beat sensations depend upon a central combination of two different temporally encoded tones, separately presented to the two ears. We tested the feasibility to record an auditory steady state evoked response (ASSR) at the binaural beat frequency in order to find a measure for temporal coding of sound in the human EEG. We stimulated each ear with a distinct tone, both differing in frequency by 40Hz, to record a binaural beat ASSR. As control, we evoked a beat ASSR in response to both tones in the same ear. We band-pass filtered the EEG at 40Hz, averaged with respect to stimulus onset and compared ASSR amplitudes and phases, extracted from a sinusoidal non-linear regression fit to a 40Hz period average. A 40Hz binaural beat ASSR was evoked at a low mean stimulus frequency (400Hz) but became undetectable beyond 3kHz. Its amplitude was smaller than that of the acoustic beat ASSR, which was evoked at low and high frequencies. Both ASSR types had maxima at fronto-central leads and displayed a fronto-occipital phase delay of several ms. The dependence of the 40Hz binaural beat ASSR on stimuli at low, temporally coded tone frequencies suggests that it may objectively assess temporal sound coding ability. The phase shift across the electrode array is evidence for more than one origin of the 40Hz oscillations. The binaural beat ASSR is an evoked response, with novel diagnostic potential, to a signal that is not present in the stimulus, but generated within the brain.

Influence of callosal transfer on visual cortical evoked response and the implication in the development of a visual prosthesis.

PubMed

Siu, Timothy L; Morley, John W

2007-12-01

The development of a visual prosthesis has been limited by an incomplete understanding of functional changes of the visual cortex accompanying deafferentation. In particular, the role of the corpus callosum in modulating these changes has not been fully evaluated. Recent experimental evidence suggests that through synaptic modulation, short-term (4-5 days) visual deafferentation can induce plastic changes in the visual cortex, leading to adaptive enhancement of residual visual input. We therefore investigated whether a compensatory rerouting of visual information can occur via the indirect transcallosal linkage after deafferentation and the influence of this interhemispheric communication on the visual evoked response of each hemisphere. In albino rabbits, misrouting of uncrossed optic fibres reduces ipsilateral input to a negligible degree. We thus took advantage of this congenital anomaly to model unilateral cortical and ocular deafferentation by eliminating visual input from one eye and recorded the visual evoked potential (VEP) from the intact eye. In keeping with the chiasmal anomaly, no VEP was elicited from the hemisphere ipsilateral to the intact eye. This remained unchanged following unilateral visual deafferentation. The amplitude and latency of the VEP in the fellow hemisphere, however, were significantly decreased in the deafferented animals. Our data suggest that callosal linkage does not contribute to visual evoked responses and this is not changed after short-term deafferentation. The decrease in amplitude and latency of evoked responses in the hemisphere ipsilateral to the treated eye, however, confirms the facilitatory role of callosal transfer. This observation highlights the importance of bicortical stimulation in the future design of a cortical visual prosthesis.

Least-squares deconvolution of evoked potentials and sequence optimization for multiple stimuli under low-jitter conditions.

PubMed

Bardy, Fabrice; Dillon, Harvey; Van Dun, Bram

2014-04-01

Rapid presentation of stimuli in an evoked response paradigm can lead to overlap of multiple responses and consequently difficulties interpreting waveform morphology. This paper presents a deconvolution method allowing overlapping multiple responses to be disentangled. The deconvolution technique uses a least-squared error approach. A methodology is proposed to optimize the stimulus sequence associated with the deconvolution technique under low-jitter conditions. It controls the condition number of the matrices involved in recovering the responses. Simulations were performed using the proposed deconvolution technique. Multiple overlapping responses can be recovered perfectly in noiseless conditions. In the presence of noise, the amount of error introduced by the technique can be controlled a priori by the condition number of the matrix associated with the used stimulus sequence. The simulation results indicate the need for a minimum amount of jitter, as well as a sufficient number of overlap combinations to obtain optimum results. An aperiodic model is recommended to improve reconstruction. We propose a deconvolution technique allowing multiple overlapping responses to be extracted and a method of choosing the stimulus sequence optimal for response recovery. This technique may allow audiologists, psychologists, and electrophysiologists to optimize their experimental designs involving rapidly presented stimuli, and to recover evoked overlapping responses. Copyright © 2013 International Federation of Clinical Neurophysiology. All rights reserved.

Independence of Echo-Threshold and Echo-Delay in the Barn Owl

PubMed Central

Nelson, Brian S.; Takahashi, Terry T.

2008-01-01

Despite their prevalence in nature, echoes are not perceived as events separate from the sounds arriving directly from an active source, until the echo's delay is long. We measured the head-saccades of barn owls and the responses of neurons in their auditory space-maps while presenting a long duration noise-burst and a simulated echo. Under this paradigm, there were two possible stimulus segments that could potentially signal the location of the echo. One was at the onset of the echo; the other, after the offset of the direct (leading) sound, when only the echo was present. By lengthening the echo's duration, independently of its delay, spikes and saccades were evoked by the source of the echo even at delays that normally evoked saccades to only the direct source. An echo's location thus appears to be signaled by the neural response evoked after the offset of the direct sound. PMID:18974886

The effect of changes in stimulus level on electrically evoked cortical auditory potentials.

PubMed

Kim, Jae-Ryong; Brown, Carolyn J; Abbas, Paul J; Etler, Christine P; O'Brien, Sara

2009-06-01

The purpose of this study was to determine whether the electrically evoked acoustic change complex (EACC) could be used to assess sensitivity to changes in stimulus level in cochlear implant (CI) recipients and to investigate the relationship between EACC amplitude and rate of growth of the N1-P2 onset response with increases in stimulus level. Twelve postlingually deafened adults using Nucleus CI24 CIs participated in this study. Nucleus Implant Communicator (NIC) routines were used to bypass the speech processor and to control the stimulation of the implant directly. The stimulus consisted of an 800 msec burst of a 1000 pps biphasic pulse train. A change in the stimulus level was introduced 400 msec after stimulus onset. Band-pass filtering (1 to 100 Hz) was used to minimize stimulus artifact. Four to six recordings of 50 sweeps were obtained for each condition, and averaged responses were analyzed in the time domain using standard peak picking procedures. Cortical auditory change potentials were recorded from CI users in response to both increases and decreases in stimulation level. The amplitude of the EACC was found to be dependent on the magnitude of the stimulus change. Increases in stimulus level elicited more robust EACC responses than decreases in stimulus level. Also, EACC amplitudes were significantly correlated with the slope of the growth of the onset response. This work describes the effect of change in stimulus level on electrically evoked auditory change potentials in CI users. The amplitude of the EACC was found to be related both to the magnitude of the stimulus change introduced and to the rate of growth of the N1-P2 onset response. To the extent that the EACC reflects processing of stimulus change, it could potentially be a valuable tool for assessing neural processing of the kinds of stimulation patterns produced by a CI. Further studies are needed, however, to determine the relationships between the EACC and psychophysical measures of intensity discrimination in CI recipients.

[Effect of the novel dipeptide nootropic agent noopept and its metabolite cyclo-L-prolylglycine on the transcallosal evoked potential in the rat brain].

PubMed

Molodavkin, G M; Borlikova, G G; Voronina, T A; Gudasheva, T A; Ostrovskaia, R U; Tushmalova, N A; Seredenin, S B

2002-01-01

The effect of new nootropic dipeptides--noopept (N-phenylacetyl-L-prolylglycine, GVS-111) and its metabolite (cyclo-L-prolylglycine)--and a standard nootrope piracetam on the transcallosal evoked potential (TEP) in rat brain was studied. In the dose range from 150 to 300 mg/kg, piracetam increased the TEP amplitude, which exhibited a maximum after 1.5-2 h and then gradually decreased. Both noopept and cyclo-L-prolylglycine also increased the TEP amplitude, which attained a plateau and retained this level over the entire observation time (above 3.5 h). All the nootropes studied increased both components of the evoked potential. Piracetam and cyclo-L-prolylglycine led to an approximately equal increase in both waves, while noopept induced a somewhat greater increase in the negative TEP wave amplitude. It is suggested that the positive effect of noopept and cyclo-L-prolylglycine upon the interhemispheric signal transfer (indicated by the improved transcallosal response) can be considered as a potential neurophysiological basis for a positive drug influence on the behavioral level.

Mapping the vestibular evoked myogenic potential (VEMP).

PubMed

Colebatch, James G

2012-01-01

Effects of different electrode placements and indifferent electrodes were investigated for the vestibular evoked myogenic potential (VEMP) recorded from the sternocleidomastoid muscle (SCM). In 5 normal volunteers, the motor point of the left SCM was identified and an electrode placed there. A grid of 7 additional electrodes was laid out, along and across the SCM, based upon the location of the motor point. One reference electrode was placed over the sternoclavicular joint and another over C7. There were clear morphological changes with differing recording sites and for the two reference electrodes, but the earliest and largest responses were recorded from the motor point. The C7 reference affected the level of rectified EMG and was associated with an initial negativity in some electrodes. The latencies of the p13 potentials increased with distance from the motor point but the n23 latencies did not. Thus the p13 potential behaved as a travelling wave whereas the n23 behaved as a standing wave. The C7 reference may be contaminated by other evoked myogenic activity. Ideally recordings should be made with an active electrode over the motor point.

The Effectiveness of FES-Evoked EMG Potentials to Assess Muscle Force and Fatigue in Individuals with Spinal Cord Injury

PubMed Central

Ibitoye, Morufu Olusola; Estigoni, Eduardo H.; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M.

2014-01-01

The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05) between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population. PMID:25025551

Music training relates to the development of neural mechanisms of selective auditory attention.

PubMed

Strait, Dana L; Slater, Jessica; O'Connell, Samantha; Kraus, Nina

2015-04-01

Selective attention decreases trial-to-trial variability in cortical auditory-evoked activity. This effect increases over the course of maturation, potentially reflecting the gradual development of selective attention and inhibitory control. Work in adults indicates that music training may alter the development of this neural response characteristic, especially over brain regions associated with executive control: in adult musicians, attention decreases variability in auditory-evoked responses recorded over prefrontal cortex to a greater extent than in nonmusicians. We aimed to determine whether this musician-associated effect emerges during childhood, when selective attention and inhibitory control are under development. We compared cortical auditory-evoked variability to attended and ignored speech streams in musicians and nonmusicians across three age groups: preschoolers, school-aged children and young adults. Results reveal that childhood music training is associated with reduced auditory-evoked response variability recorded over prefrontal cortex during selective auditory attention in school-aged child and adult musicians. Preschoolers, on the other hand, demonstrate no impact of selective attention on cortical response variability and no musician distinctions. This finding is consistent with the gradual emergence of attention during this period and may suggest no pre-existing differences in this attention-related cortical metric between children who undergo music training and those who do not. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Metabolic demands of neural-hemodynamic associated and disassociated areas in brain.

PubMed

Sanganahalli, Basavaraju G; Herman, Peter; Rothman, Douglas L; Blumenfeld, Hal; Hyder, Fahmeed

2016-10-01

Interpretation of regional blood oxygenation level-dependent (BOLD) responses in functional magnetic resonance imaging (fMRI) is contingent on whether local field potential (LFP) and multi-unit activity (MUA) is either dissociated or associated. To examine whether neural-hemodynamic associated and dissociated areas have different metabolic demands, we recorded sensory-evoked responses of BOLD signal, blood flow (CBF), and blood volume (CBV), which with calibrated fMRI provided oxidative metabolism (CMR O2 ) from rat's ventral posterolateral thalamic nucleus (VPL) and somatosensory forelimb cortex (S1 FL ) and compared these neuroimaging signals to neurophysiological recordings. MUA faithfully recorded evoked latency differences between VPL and S1 FL because evoked MUA in these regions were similar in magnitude. Since evoked LFP was significantly attenuated in VPL, we extracted the time courses of the weaker thalamic LFP to compare with the stronger cortical LFP using wavelet transform. BOLD and CBV responses were greater in S1 FL than in VPL, similar to LFP regional differences. CBF and CMR O2 responses were both comparably larger in S1 FL and VPL. Despite different levels of CBF-CMR O2 and LFP-MUA couplings in VPL and S1 FL , the CMR O2 was well matched with MUA in both regions. These results suggest that neural-hemodynamic associated and dissociated areas in VPL and S1 FL can have similar metabolic demands. © The Author(s) 2016.

Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

PubMed

Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

2012-01-01

Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. Copyright © 2011 John Wiley & Sons, Ltd.

The Direct Detection of a Single Evoked Action Potential with Magnetic Resonance Spectroscopy in Lumbricus Terrestris

PubMed Central

Poplawsky, Alexander J.; Dingledine, Raymond

2011-01-01

Functional MRI (fMRI) indirectly measures neural activity by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In the present study, we used magnetic resonance to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free-induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of [-1.2 ± 0.3] ×10-5 radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase due to a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using magnetic resonance. PMID:21728204

Vestibular Evoked Myogenic Potentials in Normal Mice and Phex Mice With Spontaneous Endolymphatic Hydrops

PubMed Central

Sheykholeslami, Kianoush; Megerian, Cliff A.; Zheng, Qing Y.

2010-01-01

Objective and Background Vestibular evoked myogenic potentials (VEMPs) have been recorded from the neck musculature and the cervical spinal cord in humans and a limited number of laboratory animals in response to loud sound. However, the mouse VEMP has yet to be described. Evaluation of the sacculocollic pathway via VEMPs in mice can set the stage for future evaluations of mutant mice that now play an important role in research regarding human auditory and vestibular dysfunction. Materials and Methods Sound-evoked potentials were recorded from the neck extensor muscles and the cervical spinal cord in normal adult mice and in circling PhexHyp-Duk/y mice with known vestibular abnormalities, including endolymphatic hydrops (ELH). Results Biphasic potentials were recorded from all normal animals. The mean threshold of the VEMP response in normal adult mice was 60 dB normal hearing level with a mean peak latency of 6.25 ± 0.46 and 7.95 ± 0.42 milliseconds for p1 and n1 peaks, respectively. At the maximum sound intensity used (100 dB normal hearing level), 4 of 5 Phex mice did not exhibit VEMP responses, and 1 showed an elevated threshold, but normal response, with regard to peak latency and amplitude. The histologic findings in all of these Phex mice were consistent with distended membranous labyrinth, displaced Reissner membrane, ganglion cell loss, and ELH. Conclusion This is the first report of VEMP recordings in mice and the first report of abnormal VEMPs in a mouse model with ELH. The characteristics of these potentials such as higher response threshold in comparison to auditory brainstem response, myogenic nature of the response, and latency correlation with the cervical recording (accessory nerve nucleus) were similar to those of VEMPs in humans, guinea pigs, cats, and rats, suggesting that the mouse may be used as an animal model in the study of VEMPs. The simplicity and reliability of these recordings make the VEMP a uniquely informative test for assessing vestibular function, and these results suggest that they may be informative in mice with various mutations. However, further investigation is necessary. PMID:19300299

Vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration applied at the nasion.

PubMed

Todd, Neil P M; McLean, Aisha; Paillard, Aurore; Kluk, Karolina; Colebatch, James G

2014-12-01

We report the results of a study to record vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration (IA). In a sample of 12 healthy participants, evoked potentials recorded by 70 channel electroencephalography were obtained by IA stimulation at the nasion and compared with evoked potentials from the same stimulus applied to the forefingers. The nasion stimulation gave rise to a series of positive and negative deflections in the latency range of 26-72 ms, which were dependent on the polarity of the applied IA. In contrast, evoked potentials from the fingers were characterised by a single N50/P50 deflection at about 50 ms and were polarity invariant. Source analysis confirmed that the finger evoked potentials were somatosensory in origin, i.e. were somatosensory evoked potentials, and suggested that the nasion evoked potentials plausibly included vestibular midline and frontal sources, as well as contributions from the eyes, and thus were likely VsEPs. These results show considerable promise as a new method for assessment of the central vestibular system by means of VsEPs produced by IA applied to the head.

Inhalational exposure to carbonyl sulfide produces altered brainstem auditory and somatosensory-evoked potentials in Fischer 344N rats.

PubMed

Herr, David W; Graff, Jaimie E; Moser, Virginia C; Crofton, Kevin M; Little, Peter B; Morgan, Daniel L; Sills, Robert C

2007-01-01

Carbonyl sulfide (COS), a chemical listed by the original Clean Air Act, was tested for neurotoxicity by a National Institute of Environmental Health Sciences/National Toxicology Program and U.S. Environmental Protection Agency collaborative investigation. Previous studies demonstrated that COS produced cortical and brainstem lesions and altered auditory neurophysiological responses to click stimuli. This paper reports the results of expanded neurophysiological examinations that were an integral part of the previously published experiments (Morgan et al., 2004, Toxicol. Appl. Pharmacol. 200, 131-145; Sills et al., 2004, Toxicol. Pathol. 32, 1-10). Fisher 334N rats were exposed to 0, 200, 300, or 400 ppm COS for 6 h/day, 5 days/week for 12 weeks, or to 0, 300, or 400 ppm COS for 2 weeks using whole-body inhalation chambers. After treatment, the animals were studied using neurophysiological tests to examine: peripheral nerve function, somatosensory-evoked potentials (SEPs) (tail/hindlimb and facial cortical regions), brainstem auditory-evoked responses (BAERs), and visual flash-evoked potentials (2-week study). Additionally, the animals exposed for 2 weeks were examined using a functional observational battery (FOB) and response modification audiometry (RMA). Peripheral nerve function was not altered for any exposure scenario. Likewise, amplitudes of SEPs recorded from the cerebellum were not altered by treatment with COS. In contrast, amplitudes and latencies of SEPs recorded from cortical areas were altered after 12-week exposure to 400 ppm COS. The SEP waveforms were changed to a greater extent after forelimb stimulation than tail stimulation in the 2-week study. The most consistent findings were decreased amplitudes of BAER peaks associated with brainstem regions after exposure to 400 ppm COS. Additional BAER peaks were affected after 12 weeks, compared to 2 weeks of treatment, indicating that additional regions of the brainstem were damaged with longer exposures. The changes in BAERs were observed in the absence of altered auditory responsiveness in FOB or RMA. This series of experiments demonstrates that COS produces changes in brainstem auditory and cortical somatosensory neurophysiological responses that correlate with previously described histopathological damage.

[Effects of sevoflurane and propofol on evoked potentials during neurosurgical anesthesia].

PubMed

Nakagawa, Itsuo; Hidaka, Syozo; Okada, Hironori; Kubo, Takashi; Okamura, Kenta; Kato, Takahiro

2006-06-01

The effect of anesthetics on somatosensory evoked potential (SEP) and auditory brain stem response (ABR) has been a subject of intense reseach over the last two decades. In fact, volatile anesthetics have been repeatedly shown to decrease cortical amplitude in a dose-dependent fashion but the information regarding the effect of propofol is incomplete. The purpose of this study was to compare the effects of sevoflurane and propofol on evoked potentials during comparable depth of anesthesia guided by bispectral index (BIS). Forty four patients scheduled for neurosurgery were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of SEP(N20-P25), ABR (V wave) and visual evoked potential (VEP: P100) at three sets of sevoflurane (0%, 1%, 2%) or propofol concentrations (effect site concentration of 1.5, 2.0, 3.0 microug x ml(-1)). BIS monitor was used to measure relative depth of hypnosis. With increasing concentrations of sevoflurane (0, 1% and 2%), SEP showed dose-related reduction in its amplitude, ABR produced less marked changes and VEP showed a significant reduction at 1%. VEP at the propofol concentration of 3.0 microg x ml(-1) was decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with SEP and ABR during the change of propofol dosages. BIS values were almost the same with each anesthetics. VEP was most strongly affected with anesthetics, and ABR showed less marked influence of sevoflurane and propofol. Propofol based TIVA technique would induce less change in evoked potentials than sevoflurane.

Selective processing of auditory evoked responses with iterative-randomized stimulation and averaging: A strategy for evaluating the time-invariant assumption.

PubMed

Valderrama, Joaquin T; de la Torre, Angel; Medina, Carlos; Segura, Jose C; Thornton, A Roger D

2016-03-01

The recording of auditory evoked potentials (AEPs) at fast rates allows the study of neural adaptation, improves accuracy in estimating hearing threshold and may help diagnosing certain pathologies. Stimulation sequences used to record AEPs at fast rates require to be designed with a certain jitter, i.e., not periodical. Some authors believe that stimuli from wide-jittered sequences may evoke auditory responses of different morphology, and therefore, the time-invariant assumption would not be accomplished. This paper describes a methodology that can be used to analyze the time-invariant assumption in jittered stimulation sequences. The proposed method [Split-IRSA] is based on an extended version of the iterative randomized stimulation and averaging (IRSA) technique, including selective processing of sweeps according to a predefined criterion. The fundamentals, the mathematical basis and relevant implementation guidelines of this technique are presented in this paper. The results of this study show that Split-IRSA presents an adequate performance and that both fast and slow mechanisms of adaptation influence the evoked-response morphology, thus both mechanisms should be considered when time-invariance is assumed. The significance of these findings is discussed. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Cortical auditory evoked potentials in the assessment of auditory neuropathy: two case studies.

PubMed

Pearce, Wendy; Golding, Maryanne; Dillon, Harvey

2007-05-01

Infants with auditory neuropathy and possible hearing impairment are being identified at very young ages through the implementation of hearing screening programs. The diagnosis is commonly based on evidence of normal cochlear function but abnormal brainstem function. This lack of normal brainstem function is highly problematic when prescribing amplification in young infants because prescriptive formulae require the input of hearing thresholds that are normally estimated from auditory brainstem responses to tonal stimuli. Without this information, there is great uncertainty surrounding the final fitting. Cortical auditory evoked potentials may, however, still be evident and reliably recorded to speech stimuli presented at conversational levels. The case studies of two infants are presented that demonstrate how these higher order electrophysiological responses may be utilized in the audiological management of some infants with auditory neuropathy.

Optical responses evoked by white matter stimulation in rat visual cortical slices and their relation to neural activities.

PubMed

Tanifuji, M; Yamanaka, A; Sunaba, R; Terakawa, S; Toyama, K

1996-10-28

To characterize optical responses (ORs) evoked by white matter (WM) stimulation in slices of rat visual cortex (VC) stained with voltage sensitive dyes, time course of ORs in each layer was investigated by recording ORs with a linearly aligned photodiode array, and the spatial patterns of the ORs at specified time after stimulation were investigated by a CCD camera in combination with stroboscopic illumination. The ORs recorded by the photodiode array were an increase in absorption at 700 nm and a decrease in the wavelength below 650 nm, suggesting that the ORs were dye related. The ORs were compared with field potentials (FPs) to clarify that neural events were represented by the ORs, and in support of this view, we found that the first order spatial differentials of ORs and that of FPs were in good agreement. We further compared ORs with intracellular responses, and found that the ORs mainly represent postsynaptic potentials (PSPs) of VC neurons except for the deeper part of layer VI, where a component representing action potentials in fibers stimulated directly was observed. The time-lapse imaging of ORs showed that excitation first propagated vertically up to layer I and subsequently in the horizontal direction along layers II-III and V-VI as in previous investigations. Spatio-temporal patterns of ORs under blockade of synaptic transmission were also investigated to reveal activity of fibers evoked by WM stimulation which produced such patterns of propagation.

Tachykininergic slow depolarization of motoneurones evoked by descending fibres in the neonatal rat spinal cord.

PubMed Central

Kurihara, T; Yoshioka, K; Otsuka, M

1995-01-01

1. In the isolated spinal cord of the neonatal rat, repetitive electrical stimulation of the upper cervical region elicited a prolonged depolarization of lumbar motoneurones (L3-5) lasting 1-2 min, which was recorded extracellularly from ventral roots, or intracellularly. 2. This depolarizing response was markedly depressed by the excitatory amino acid receptor antagonists D-(-)-2-amino-5-phosphonovaleric acid (D-APV, 30 microM) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM). The remaining response was further depressed by a 5-hydroxytryptamine (5-HT) receptor antagonist, ketanserin (3 microM). 3. In the presence of these antagonists, a small part of the depolarizing response of slow time course remained, and this response was partially blocked by the tachykinin NK1 receptor antagonists GR71251 (0.3-5 microM) and RP67580 (0.3-1 microM). In contrast, RP68651 (0.3-1 microM), the inactive enantiomer of RP67580, had no effect on the depolarizing response. 4. The slow depolarizing response in the presence of D-APV, CNQX and ketanserin was markedly potentiated by a peptidase inhibitor, thiorphan (1 microM). 5. This descending fibre-evoked slow depolarization became smaller after prolonged treatment (5-7 h) with 5,7-dihydroxytryptamine (10 microM), a neurotoxin for 5-HT neurones. Under such conditions, the effects of thiorphan and GR71251 on the slow depolarization were virtually absent. 6. Under the action of D-APV, CNQX and ketanserin, applications of tachykinins, substance P and neurokinin A produced depolarizing responses of lumbar motoneurones, and the responses were depressed by GR71251 and potentiated by thiorphan. 7. These results suggest that tachykinins contained in serotonergic fibres serve as neurotransmitters mediating the descending fibre-evoked slow excitatory postsynaptic potentials in motoneurones. PMID:7562617

The Electrophysiology of Electric Organs of Marine Electric Fishes

PubMed Central

Bennett, M. V. L.; Wurzel, M.; Grundfest, H.

1961-01-01

Single electroplaques of Torpedo nobiliana have been studied with microelectrode recording. Direct evidence is presented that the only electrogenically reactive membrane of the cells is on the innervated surface and that this membrane is electrically inexcitable. Responses are not evoked by depolarizing currents applied to this membrane, but only by stimulating the innervating nerve fibers. The responses arise after a latency of 1 to 3 msec. This latency is not affected by large depolarizing or hyperpolarizing changes in membrane potential. Various properties that have been theoretically associated with electrically inexcitable responses have been also demonstrated to occur in the electroplaques. The neurally evoked response is not propagated actively in the membrane and may have different amplitudes and forms in closely adjacent regions. The maximal responses frequently are slightly larger than the recorded resting potential but the apparent small overshoot may be due to difficulty in recording the full resting potential. The responses are subject to electrochemical gradation and appear inverted in sign on applying strong outward currents across the innervated membrane. This membrane is cholinoceptive and shows marked desensitization. The membrane of the uninnervated surface has a very low resistance, a factor that aids maximum output of current during the discharge of the electric organ. PMID:19873534

Sex Differences in Orienting to Pictures with and without Humans: Evidence from the Cardiac Evoked Response (ECR) and the Cortical Long Latency Parietal Positivity (LPP)

PubMed Central

Althaus, Monika; Groen, Yvonne; van der Schaft, Lutske; Minderaa, Ruud B.; Tucha, Oliver; Mulder, Lambertus J. M.; Wijers, Albertus A.

2014-01-01

Objective This study investigated the effect of social relevance in affective pictures on two orienting responses, i.e. the evoked cardiac response (ECR), and a long latency cortical evoked potential (LPP) and whether this effect would differ between males and females. Assuming that orienting to affective social information is fundamental to experiencing affective empathy, associations between self-report measures of empathy and the two orienting responses were investigated. Method ECRs were obtained from 34 female and 30 male students, and LPPs from 25 female and 27 male students viewing 414 pictures from the International Affective Picture System. Pictures portrayed pleasant, unpleasant and neutral scenes with and without humans. Results Both the ECR and LPP showed the largest response to pictures with humans in unpleasant situations. For both measures, the responses to pictures with humans correlated with self-report measures of empathy. While we found a greater male than female responsiveness to the pictures without humans in the ECR, a greater female than male responsiveness was observed in the LPP response to pictures with humans. Conclusion and Significance The sensitivity of these orienting responses to social relevance and their differential contribution to the prediction of individual differences underline the validity of their combined use in clinical studies investigating individuals with social disabilities. PMID:25330003

Use of NK1 receptor antagonists in the exploration of physiological functions of substance P and neurokinin A.

PubMed

Otsuka, M; Yoshioka, K; Yanagisawa, M; Suzuki, H; Zhao, F Y; Guo, J Z; Hosoki, R; Kurihara, T

1995-07-01

Tachykinin NK1 receptor antagonists were used to explore the physiological functions of substance P (SP) and neurokinin A (NKA). Pharmacological profiles of three NK1 receptor antagonists, GR71251, GR82334, and RP 67580, were examined in the isolated spinal cord preparation of the neonatal rat. These tachykinin receptor antagonists exhibited considerable specificities and antagonized the actions of both SP and NKA to induce the depolarization of ventral roots. Electrical stimulation of the saphenous nerve with C-fiber strength evoked a depolarization lasting about 30 s of the ipsilateral L3 ventral root. This response, which is referred to as saphenous-nerve-evoked slow ventral root potential (VRP), was depressed by these NK1 receptor antagonists. In contrast, the saphenous-nerve-evoked slow VRP was potentiated by application of a mixture of peptidase inhibitors, including thiorphan, actinonin, and captopril in the presence of naloxone, but not after further addition of GR71251. Likewise, in the isolated coeliac ganglion of the guinea pig, electrical stimulation of the mesenteric nerves evoked in some ganglionic cells slow excitatory postsynaptic potentials (EPSPs), which were depressed by GR71251 and potentiated by peptidase inhibitors. These results further support the notion that SP and NKA serve as neurotransmitters producing slow EPSPs in the neonatal rat spinal cord and guinea pig prevertebral ganglia.

Excitation of the corticospinal tract by electromagnetic and electrical stimulation of the scalp in the macaque monkey.

PubMed Central

Edgley, S A; Eyre, J A; Lemon, R N; Miller, S

1990-01-01

1. The responses evoked by non-invasive electromagnetic and surface anodal electrical stimulation of the scalp (scalp stimulation) have been studied in the monkey. Conventional recording and stimulating electrodes, placed in the corticospinal pathway in the hand area of the left motor cortex, left medullary pyramid and the right spinal dorsolateral funiculus (DLF), allowed comparison of the actions of non-invasive stimuli and conventional electrical stimulation. 2. Responses to electromagnetic stimulation (with the coil tangential to the skull) were studied in four anaesthetized monkeys. In each case short-latency descending volleys were recorded in the contralateral DLF at threshold. In two animals later responses were also seen at higher stimulus intensities. Both early and late responses were of corticospinal origin since they could be completely collided by appropriately timed stimulation of the pyramidal tract. The latency of the early response in the DLF indicated that it resulted from direct activation of corticospinal neurones: its latency was the same as the latency of the antidromic action potentials evoked in the motor cortex from the recording site in the DLF. 3. Scalp stimulation, which was also investigated in three of the monkeys, evoked short-latency volleys at threshold and at higher stimulus intensities these were followed by later waves. The short-latency volleys could be collided from the pyramid and, at threshold, had latencies compatible with direct activation of corticospinal neurones. The longer latency volleys were also identified as corticospinal in origin. 4. The latency of the early volley evoked by electromagnetic stimulation remained constant with increasing stimulus intensities. In contrast, with scalp stimulation above threshold the latency of the early volleys decreased considerably, indicating remote activation of the corticospinal pathway below the level of the motor cortex. In two monkeys both collision and latency data suggest activation of the corticospinal pathway as far caudal as the medulla. 5. The majority of fast corticospinal fibres could be excited by scalp stimulation with intensities of 20% of maximum stimulator output. Electromagnetic stimulation at maximum stimulator output elicited a volley of between 70 and 90% of the size of the maximal volley evoked from the pyramidal electrodes. 6. Electromagnetic stimulation was also investigated in one awake monkey during the performance of a precision grip task. Short-latency EMG responses were evoked in hand and forearm muscles. The onsets of these responses were approximately 0.8 ms longer than the responses evoked by electrical stimulation of the pyramid.(ABSTRACT TRUNCATED AT 400 WORDS) Images Fig. 1 PMID:2213581

Effect of neck flexion on somatosensory and motor evoked potentials in Hirayama disease.

PubMed

Abraham, A; Gotkine, M; Drory, V E; Blumen, S C

2013-11-15

Hirayama disease (HD) is a rare motor disorder mainly affecting young men, characterized by atrophy and weakness of forearm and hand muscles corresponding to a C7-T1 myotome distribution. The weakness is usually unilateral or asymmetric and progression usually stops within several years. The etiology of HD is not well understood. One hypothesis, mainly based on MRI findings, is that the weakness is a consequence of cervical flexion myelopathy. The aim of this study was to explore the function of corticospinal and ascending somatosensory pathways during neck flexion using evoked responses. 15 men with HD and 7 age-matched control male subjects underwent somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) studies with the neck in neutral position and fully flexed. SSEP studies included electrical stimulation of median and ulnar nerves at the wrist, and tibial nerve at the ankle with recording over the ipsilateral Erb's point, cervical spine, and contralateral sensory cortex. MEP recordings were obtained by magnetic stimulation of the motor cortex and the cervical lower spinal roots; the evoked responses were recorded from the contralateral thenar and abductor hallucis muscles. MEP recordings demonstrated significant lower amplitudes, and slightly prolonged latencies in HD patients on cervical stimulation, compared to control subjects. During neck flexion, MEP studies also demonstrated a statistically significant drop in mean upper limb amplitude on cervical stimulation in HD patients, as well as in control subjects, although to a lesser degree. In contrast, no significant differences were found in SSEP studies in HD patients compared to control subjects, or between neutral and flexed position in these groups. The study shows a negative effect of cervical flexion on MEP amplitudes in HD patients as well as in control subjects, requiring more studies to investigate its significance. Neck flexion did not have an influence on any SSEP parameters in patients or controls. © 2013 Elsevier B.V. All rights reserved.

Comparison of Infant and Adult P300 from Auditory Stimuli.

ERIC Educational Resources Information Center

McIsaac, Heather; Polich, John

1992-01-01

Recorded electroencephalographic activity of infants and adults who heard 1 unique tone in a series of 10 tones. The amplitude of event-related brain potentials in response to the unique tone was smaller, and its latency longer, for infants than for adults. Evoked potentials remained stable across trials. (BC)

Challenges of recording human fetal auditory-evoked response using magnetoencephalography.

PubMed

Eswaran, H; Lowery, C L; Robinson, S E; Wilson, J D; Cheyne, D; McKenzie, D

2000-01-01

Our goals were to successfully perform fetal auditory-evoked responses using the magnetoencephalography technique, understand its problems and limitations, and propose instrument design modifications to improve the signal quality and success rate. Fetal auditory-evoked responses were recorded from four fetuses with gestational ages ranging from 33-40+ weeks. The signals were recorded using a gantry-based superconducting quantum interference device. Auditory stimulus was 1 kHz tone burst. The evoked signals were digitized and averaged over an 800 ms window. After several trials of positioning and repositioning the subjects, we were able to record auditory-evoked responses in three out of the four fetuses. Since the superconducting quantum interference device array design was not shaped to fit over the mother's abdomen, we experienced difficulty in positioning the sensors over the fetal head. Based on this pilot study, we propose instrument design that may improve signal quality and success rate of the fetal magnetic auditory-evoked response.

Respiration Gates Sensory Input Responses in the Mitral Cell Layer of the Olfactory Bulb

PubMed Central

Short, Shaina M.; Morse, Thomas M.; McTavish, Thomas S.; Shepherd, Gordon M.; Verhagen, Justus V.

2016-01-01

Respiration plays an essential role in odor processing. Even in the absence of odors, oscillating excitatory and inhibitory activity in the olfactory bulb synchronizes with respiration, commonly resulting in a burst of action potentials in mammalian mitral/tufted cells (MTCs) during the transition from inhalation to exhalation. This excitation is followed by inhibition that quiets MTC activity in both the glomerular and granule cell layers. Odor processing is hypothesized to be modulated by and may even rely on respiration-mediated activity, yet exactly how respiration influences sensory processing by MTCs is still not well understood. By using optogenetics to stimulate discrete sensory inputs in vivo, it was possible to temporally vary the stimulus to occur at unique phases of each respiration. Single unit recordings obtained from the mitral cell layer were used to map spatiotemporal patterns of glomerular evoked responses that were unique to stimulations occurring during periods of inhalation or exhalation. Sensory evoked activity in MTCs was gated to periods outside phasic respiratory mediated firing, causing net shifts in MTC activity across the cycle. In contrast, odor evoked inhibitory responses appear to be permitted throughout the respiratory cycle. Computational models were used to further explore mechanisms of inhibition that can be activated by respiratory activity and influence MTC responses. In silico results indicate that both periglomerular and granule cell inhibition can be activated by respiration to internally gate sensory responses in the olfactory bulb. Both the respiration rate and strength of lateral connectivity influenced inhibitory mechanisms that gate sensory evoked responses. PMID:28005923

Single passive leg movement-induced hyperemia: a simple vascular function assessment without a chronotropic response.

PubMed

Venturelli, Massimo; Layec, Gwenael; Trinity, Joel; Hart, Corey R; Broxterman, Ryan M; Richardson, Russell S

2017-01-01

Passive leg movement (PLM)-induced hyperemia is a novel approach to assess vascular function, with a potential clinical role. However, in some instances, the varying chronotropic response induced by PLM has been proposed to be a potentially confounding factor. Therefore, we simplified and modified the PLM model to require just a single PLM (sPLM), an approach that may evoke a peripheral hemodynamic response, allowing a vascular function assessment, but at the same time minimizing central responses. To both characterize and assess the utility of sPLM, in 12 healthy subjects, we measured heart rate (HR), stroke volume, cardiac output (CO), mean arterial pressure (MAP), leg blood flow (LBF), and calculated leg vascular conductance (LVC) during both standard PLM, consisting of passive knee flexion and extension performed at 1 Hz for 60 s, and sPLM, consisting of only a single passive knee flexion and extension over 1 s. During PLM, MAP transiently decreased (5 ± 1 mmHg), whereas both HR and CO increased from baseline (6.0 ± 1.1 beats/min, and 0.8 ± 0.01 l/min, respectively). Following sPLM, MAP fell similarly (5 ± 2 mmHg; P = 0.8), but neither HR nor CO responses were identifiable. The peak LBF and LVC response was similar for PLM (993 ± 189 ml/min; 11.9 ± 1.5 ml·min -1 ·mmHg -1 , respectively) and sPLM (878 ± 119 ml/min; 10.9 ± 1.6 ml·min -1 ·mmHg -1 , respectively). Thus sPLM represents a variant of the PLM approach to assess vascular function that is more easily performed and evokes a peripheral stimulus that induces a significant hyperemia, but does not generate a potentially confounding, chronotropic response, which may make sPLM more useful clinically. Using the single passive leg movement (PLM) technique, a variant of the vascular function assessment PLM, we have identified a novel peripheral vascular assessment method that is more easily performed than PLM, which, by not evoking potentially confounding central hemodynamic responses, may be more useful clinically.

Vestibular evoked myogenic potentials in response to lateral skull taps are dependent on two different mechanisms.

PubMed

Brantberg, Krister; Westin, Magnus; Löfqvist, Lennart; Verrecchia, Luca; Tribukait, Arne

2009-05-01

To explore the mechanisms for skull tap induced vestibular evoked myogenic potentials (VEMP). The muscular responses were recorded over both sternocleidomastoid (SCM) muscles using skin electrodes. A skull tapper which provided a constant stimulus intensity was used to test cervical vestibular evoked myogenic potentials (VEMP) in response to lateral skull taps in healthy subjects (n=10) and in patients with severe unilateral loss of vestibular function (n=10). Skull taps applied approximately 2 cm above the outer ear canal caused highly reproducible VEMP. There were differences in VEMP in both normals and patients depending on side of tapping. In normals, there was a positive-negative ("normal") VEMP on the side contra-lateral to the skull tapping, but no significant VEMP ipsi-laterally. In patients, skull taps above the lesioned ear caused a contra-lateral positive-negative VEMP (as it did in the normals), in addition there was an ipsi-lateral negative-positive ("inverted") VEMP. When skull taps were presented above the healthy ear there was only a small contra-lateral positive-negative VEMP but, similar to the normals, no VEMP ipsi-laterally. The present data, in conjunction with earlier findings, support a theory that skull-tap VEMP responses are mediated by two different mechanisms. It is suggested that skull tapping causes both a purely ipsi-lateral stimulus side independent SCM response and a bilateral and of opposite polarity SCM response that is stimulus side dependent. Possibly, the skull tap induced VEMP responses are the sum of a stimulation of two species of vestibular receptors, one excited by vibration (which is rather stimulus site independent) and one excited by translation (which is more stimulus site dependent). Skull-tap VEMP probably have two different mechanisms. Separation of the two components might reveal the status of different labyrinthine functions.

Differential behavioral sensitivity to carbon dioxide (CO2) inhalation in rats

PubMed Central

Winter, Andrew; Ahlbrand, Rebecca; Naik, Devanshi; Sah, Renu

2017-01-01

Inhalation of carbon dioxide (CO2) is frequently employed as a biological challenge to evoke intense fear and anxiety. In individuals with panic disorder, CO2 reliably evokes panic attacks. Sensitivity to CO2 is highly heterogeneous among individuals, and although a genetic component is implicated, underlying mechanisms are not clear. Preclinical models that can simulate differential responsivity to CO2 are therefore relevant. In the current study we investigated CO2-evoked behavioral responses in four different rat strains: Sprague-Dawley (SD), Wistar (W), Long Evans (LE) and Wistar-Kyoto, (WK) rats. We also assessed tryptophan hydroxylase 2 (TPH-2)-positive serotonergic neurons in anxiety/panic regulatory subdivisions of the dorsal raphe nucleus (DR), as well as dopamine β hydroxylase (DβH)-positive noradrenergic neurons in the locus coeruleus, implicated in central CO2-chemosensitivity. Behavioral responsivity to CO2 inhalation varied between strains. CO2-evoked immobility was significantly higher in LE and WK rats as compared with W and SD cohorts. Differences were also observed in CO2-evoked rearing and grooming behaviors. Exposure to CO2 did not produce conditioned behavioral responses upon re-exposure to CO2 context in any strain. Reduced TPH-2 positive cell counts were observed specifically in the panic-regulatory dorsal raphe ventrolateral (DRVL)-ventrolateral periaqueductal grey (VLPAG) subdivision in CO2-sensitive strains. Conversely, DβH positive cell counts within the LC were significantly higher in CO2-sensitive strains. Collectively, our data provide evidence for strain dependent, differential CO2-sensitivity and potential differences in monoaminergic systems regulating panic and anxiety. Comparative studies between CO2-vulnerable and resistant strains may facilitate the mechanistic understanding of differential CO2-sensitivity in the development of panic and anxiety disorders. PMID:28087339

Using Transcranial Magnetic Stimulation to Evaluate the Motor Pathways After an Intraoperative Spinal Cord Injury and to Predict the Recovery of Intraoperative Transcranial Electrical Motor Evoked Potentials: A Case Report.

PubMed

Grover, Helen J; Thornton, Rachel; Lutchman, Lennel N; Blake, Julian C

2016-06-01

The authors report a case of unilateral loss of intraoperative transcranial electrical motor evoked potentials (TES MEP) associated with a spinal cord injury during scoliosis correction and the subsequent use of extraoperative transcranial magnetic stimulation to monitor the recovery of spinal cord function. The authors demonstrate the absence of TES MEPs and absent transcranial magnetic stimulation responses in the immediate postoperative period, and document the partial recovery of transcranial magnetic stimulation responses, which corresponded to partial recovery of TES MEPs. Intraoperative TES MEPs were enhanced using spatial facilitation technique, which enabled the patient to undergo further surgery to stabilize the spine and correct her scoliosis. This case report supports evidence of the use of extraoperative transcranial magnetic stimulation to predict the presence of intraoperative TES responses and demonstrates the usefulness of spatial facilitation to monitor TES MEPs in a patient with a preexisting spinal cord injury.

Pain Processing and Vegetative Dysfunction in Fibromyalgia: A Study by Sympathetic Skin Response and Laser Evoked Potentials

PubMed Central

Ricci, Katia; Libro, Giuseppe; Vecchio, Eleonora; Delussi, Marianna; Montemurno, Anna; Iannone, Florenzo

2017-01-01

Background A dysfunction of pain processing at central and peripheral levels was reported in fibromyalgia (FM). We aimed to correlate laser evoked potentials (LEPs), Sympathetic Skin Response (SSR), and clinical features in FM patients. Methods Fifty FM patients and 30 age-matched controls underwent LEPs and SSR by the right hand and foot. The clinical evaluation included FM disability (FIQ) and severity scores (WPI), anxiety (SAS) and depression (SDS) scales, and questionnaires for neuropathic pain (DN4). Results The LEP P2 latency and amplitude and the SSR latency were increased in FM group. This latter feature was more evident in anxious patients. The LEPs habituation was reduced in FM patients and correlated to pain severity scores. In a significant number of patients (32%) with higher DN4 and FIQ scores, SSR or LEP responses were absent. Conclusions LEPs and SSR might contribute to clarifying the peripheral and central nervous system involvement in FM patients. PMID:29093972

Pain Processing and Vegetative Dysfunction in Fibromyalgia: A Study by Sympathetic Skin Response and Laser Evoked Potentials.

PubMed

de Tommaso, Marina; Ricci, Katia; Libro, Giuseppe; Vecchio, Eleonora; Delussi, Marianna; Montemurno, Anna; Lopalco, Giuseppe; Iannone, Florenzo

2017-01-01

A dysfunction of pain processing at central and peripheral levels was reported in fibromyalgia (FM). We aimed to correlate laser evoked potentials (LEPs), Sympathetic Skin Response (SSR), and clinical features in FM patients. Fifty FM patients and 30 age-matched controls underwent LEPs and SSR by the right hand and foot. The clinical evaluation included FM disability (FIQ) and severity scores (WPI), anxiety (SAS) and depression (SDS) scales, and questionnaires for neuropathic pain (DN4). The LEP P2 latency and amplitude and the SSR latency were increased in FM group. This latter feature was more evident in anxious patients. The LEPs habituation was reduced in FM patients and correlated to pain severity scores. In a significant number of patients (32%) with higher DN4 and FIQ scores, SSR or LEP responses were absent. LEPs and SSR might contribute to clarifying the peripheral and central nervous system involvement in FM patients.

The Involvement of Endogenous Neural Oscillations in the Processing of Rhythmic Input: More Than a Regular Repetition of Evoked Neural Responses

PubMed Central

Zoefel, Benedikt; ten Oever, Sanne; Sack, Alexander T.

2018-01-01

It is undisputed that presenting a rhythmic stimulus leads to a measurable brain response that follows the rhythmic structure of this stimulus. What is still debated, however, is the question whether this brain response exclusively reflects a regular repetition of evoked responses, or whether it also includes entrained oscillatory activity. Here we systematically present evidence in favor of an involvement of entrained neural oscillations in the processing of rhythmic input while critically pointing out which questions still need to be addressed before this evidence could be considered conclusive. In this context, we also explicitly discuss the potential functional role of such entrained oscillations, suggesting that these stimulus-aligned oscillations reflect, and serve as, predictive processes, an idea often only implicitly assumed in the literature. PMID:29563860

Jealousy in response to online and offline infidelity: the role of sex and sexual orientation.

PubMed

Dijkstra, Pieternel; Barelds, Dick P H; Groothof, Hinke A K

2013-08-01

The goal of the present study was to examine the emotional content and intensity of jealousy in response to different types of infidelity (both online and offline unfaithful partner behaviors) among Dutch heterosexuals (n = 191) and homosexuals (n = 121). Based on previous research (Dijkstra, Barelds & Groothof, 2010), participants were presented with ten jealousy-evoking situations following which the intensity of two different emotional aspects of jealousy was assessed (betrayal/anger and threat). Results showed that scenarios describing a partner having sex with someone else or falling in love with someone else primarily evoked betrayal/anger-related jealousy, whereas scenarios describing an emotional connection between a partner and someone else primarily evoked threat-related jealousy. In addition, women experienced more jealousy than men in response to scenarios in which a partner engaged in potentially extra-dyadic online (but not offline) behaviors. Finally, compared to same-sex heterosexuals, homosexuals, both male and female, responded with less intense jealousy to scenarios describing a partner having sex with someone else. Implications for the treatment of (internet) infidelity are discussed. © 2013 The Scandinavian Psychological Associations.

21 CFR 882.1900 - Evoked response auditory stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Evoked response auditory stimulator. 882.1900 Section 882.1900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1900 Evoked response...

21 CFR 882.1880 - Evoked response mechanical stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Evoked response mechanical stimulator. 882.1880 Section 882.1880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1880 Evoked response...

21 CFR 882.1890 - Evoked response photic stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Evoked response photic stimulator. 882.1890 Section 882.1890 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1890 Evoked response...

21 CFR 882.1900 - Evoked response auditory stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Evoked response auditory stimulator. 882.1900 Section 882.1900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1900 Evoked response...

21 CFR 882.1890 - Evoked response photic stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Evoked response photic stimulator. 882.1890 Section 882.1890 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1890 Evoked response...

Ex vivo human pancreatic slice preparations offer a valuable model for studying pancreatic exocrine biology.

PubMed

Liang, Tao; Dolai, Subhankar; Xie, Li; Winter, Erin; Orabi, Abrahim I; Karimian, Negar; Cosen-Binker, Laura I; Huang, Ya-Chi; Thorn, Peter; Cattral, Mark S; Gaisano, Herbert Y

2017-04-07

A genuine understanding of human exocrine pancreas biology and pathobiology has been hampered by a lack of suitable preparations and reliance on rodent models employing dispersed acini preparations. We have developed an organotypic slice preparation of the normal portions of human pancreas obtained from cancer resections. The preparation was assessed for physiologic and pathologic responses to the cholinergic agonist carbachol (Cch) and cholecystokinin (CCK-8), including 1) amylase secretion, 2) exocytosis, 3) intracellular Ca 2+ responses, 4) cytoplasmic autophagic vacuole formation, and 5) protease activation. Cch and CCK-8 both dose-dependently stimulated secretory responses from human pancreas slices similar to those previously observed in dispersed rodent acini. Confocal microscopy imaging showed that these responses were accounted for by efficient apical exocytosis at physiologic doses of both agonists and by apical blockade and redirection of exocytosis to the basolateral plasma membrane at supramaximal doses. The secretory responses and exocytotic events evoked by CCK-8 were mediated by CCK-A and not CCK-B receptors. Physiologic agonist doses evoked oscillatory Ca 2+ increases across the acini. Supraphysiologic doses induced formation of cytoplasmic autophagic vacuoles and activation of proteases (trypsin, chymotrypsin). Maximal atropine pretreatment that completely blocked all the Cch-evoked responses did not affect any of the CCK-8-evoked responses, indicating that rather than acting on the nerves within the pancreas slice, CCK cellular actions directly affected human acinar cells. Human pancreas slices represent excellent preparations to examine pancreatic cell biology and pathobiology and could help screen for potential treatments for human pancreatitis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Asymmetry of magnetic motor evoked potentials recorded in calf muscles of the dominant and non-dominant lower extremity.

PubMed

Olex-Zarychta, Dorota; Koprowski, Robert; Sobota, Grzegorz; Wróbel, Zygmunt

2009-08-07

The aim of the study was to determine the applicability of magnetic stimulation and magnetic motor evoked potentials (MEPs) in motor asymmetry studies by obtaining quantitative and qualitative measures of efferent activity during low intensity magnetic stimulation of the dominant and non-dominant lower extremities. Magnetic stimulation of the tibial nerve in the popliteal fossa was performed in 10 healthy male right-handed and right-footed young adults. Responses were recorded from the lateral head of the gastrocnemius muscles of the right and left lower extremities. Response characteristics (duration, onset latency, amplitude) were analyzed in relation to the functional dominance of the limbs and in relation to the direction of the current in the magnetic coil by use of the Wilcoxon pair sequence test. The CCW direction of coil current was related to reduced amplitudes of recorded MEPs. Greater amplitudes of evoked potentials were recorded in the non-dominant extremity, both in the CW and CCW coil current directions, with the statistical significance of this effect (p=0.005). No differences in duration of response were found in the CW current direction, while in CCW the time of the left-side response was prolonged (p=0.01). In the non-dominant extremity longer onset latencies were recorded in both current directions, but only for the CW direction the side asymmetries showed a statistical significance of p=0.005. In the dominant extremity the stimulation correlated with stronger paresthesias, especially using the CCW direction of coil current. The results indicate that low intensity magnetic stimulation may be useful in quantitative and qualitative research into the motor asymmetry.

An "oblique effect" in the visual evoked potential of the cat.

PubMed

Bonds, A B

1982-01-01

An oblique effect was observed in the amplitude of the VEP recorded from area 17 of the cat. The ratio of the responses to oblique gratings compared with responses to horizontal and vertical gratings averaged 0.77. Orientation dependence was strongest at low spatial frequencies, unlike the effect found in primates.

21 CFR 882.1880 - Evoked response mechanical stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Evoked response mechanical stimulator. 882.1880... mechanical stimulator. (a) Identification. An evoked response mechanical stimulator is a device used to produce a mechanical stimulus or a series of mechanical stimuli for the purpose of measuring a patient's...

21 CFR 882.1870 - Evoked response electrical stimulator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Evoked response electrical stimulator. 882.1870... electrical stimulator. (a) Identification. An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring the...

21 CFR 882.1870 - Evoked response electrical stimulator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Evoked response electrical stimulator. 882.1870... electrical stimulator. (a) Identification. An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring the...

21 CFR 882.1870 - Evoked response electrical stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Evoked response electrical stimulator. 882.1870... electrical stimulator. (a) Identification. An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring the...

21 CFR 882.1870 - Evoked response electrical stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Evoked response electrical stimulator. 882.1870... electrical stimulator. (a) Identification. An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring the...

Whole-brain diffusion tensor imaging in correlation to visual-evoked potentials in multiple sclerosis: a tract-based spatial statistics analysis.

PubMed

Lobsien, D; Ettrich, B; Sotiriou, K; Classen, J; Then Bergh, F; Hoffmann, K-T

2014-01-01

Functional correlates of microstructural damage of the brain affected by MS are incompletely understood. The purpose of this study was to evaluate correlations of visual-evoked potentials with microstructural brain changes as determined by DTI in patients with demyelinating central nervous disease. Sixty-one patients with clinically isolated syndrome or MS were prospectively recruited. The mean P100 visual-evoked potential latencies of the right and left eyes of each patient were calculated and used for the analysis. For DTI acquisition, a single-shot echo-planar imaging pulse sequence with 80 diffusion directions was performed at 3T. Fractional anisotropy, radial diffusivity, and axial diffusivity were calculated and correlated with mean P100 visual-evoked potentials by tract-based spatial statistics. Significant negative correlations between mean P100 visual-evoked potentials and fractional anisotropy and significant positive correlations between mean P100 visual-evoked potentials and radial diffusivity were found widespread over the whole brain. The highest significance was found in the optic radiation, frontoparietal white matter, and corpus callosum. Significant positive correlations between mean P100 visual-evoked potentials and axial diffusivity were less widespread, notably sparing the optic radiation. Microstructural changes of the whole brain correlated significantly with mean P100 visual-evoked potentials. The distribution of the correlations showed clear differences among axial diffusivity, fractional anisotropy, and radial diffusivity, notably in the optic radiation. This finding suggests a stronger correlation of mean P100 visual-evoked potentials to demyelination than to axonal damage. © 2014 by American Journal of Neuroradiology.

Vestibular-evoked myogenic potential in response to bone-conducted sound in patients with otosclerosis

PubMed Central

Seo, Toru; Fujimori, Kiyoko; Mishiro, Yasuo; Sakagami, Masafumi

2012-01-01

Conclusion: Saccular dysfunction is a major cause of balance problems in patients with otosclerosis. Vestibular-evoked myogenic potential in response to bone-conducted sound (BC-VEMP) testing is useful for diagnosis of these patients. Objectives: The purpose of this study was to elucidate the origin of balance problems in patients with otosclerosis using BC-VEMP. Methods: Subjects comprised 25 patients with unoperated otosclerosis (9 men and 16 women). They were divided into two groups depending on type of balance problems. Results of cochleo-vestibular functions including pure-tone audiometry, caloric testing, and BC-VEMP testing were compared between the two groups. Results: Ten patients had complained of dizziness and/or vertigo (disequilibrium group), and the other 15 patients had not (Non-disequilibrium group). Nine patients showed abnormal results on BC-VEMP testing in the disequilibrium group, while one patient had abnormal results in the non-disequilibrium group (p < 0.001). PMID:22830649

Electrophysiological studies of the nervous system

NASA Technical Reports Server (NTRS)

Galambos, R.

1972-01-01

The electrophysiology of the nervous system is studied using cats and human subjects. Data cover effects of chlorolose on evoked potential, the evoked resistance shift that accompanies evoked potentials, and the relationship of eye movements to potentials aroused by visual stimulation.

Modeling and measurement of vesicle pools at the cone ribbon synapse: changes in release probability are solely responsible for voltage-dependent changes in release

PubMed Central

Thoreson, Wallace B.; Van Hook, Matthew J.; Parmelee, Caitlyn; Curto, Carina

2015-01-01

Post-synaptic responses are a product of quantal amplitude (Q), size of the releasable vesicle pool (N), and release probability (P). Voltage-dependent changes in presynaptic Ca2+ entry alter post-synaptic responses primarily by changing P but have also been shown to influence N. With simultaneous whole cell recordings from cone photoreceptors and horizontal cells in tiger salamander retinal slices, we measured N and P at cone ribbon synapses by using a train of depolarizing pulses to stimulate release and deplete the pool. We developed an analytical model that calculates the total pool size contributing to release under different stimulus conditions by taking into account the prior history of release and empirically-determined properties of replenishment. The model provided a formula that calculates vesicle pool size from measurements of the initial post-synaptic response and limiting rate of release evoked by a train of pulses, the fraction of release sites available for replenishment, and the time constant for replenishment. Results of the model showed that weak and strong depolarizing stimuli evoked release with differing probabilities but the same size vesicle pool. Enhancing intraterminal Ca2+ spread by lowering Ca2+ buffering or applying BayK8644 did not increase PSCs evoked with strong test steps showing there is a fixed upper limit to pool size. Together, these results suggest that light-evoked changes in cone membrane potential alter synaptic release solely by changing release probability. PMID:26541100

Anti-Aversive Effects of Cannabidiol on Innate Fear-Induced Behaviors Evoked by an Ethological Model of Panic Attacks Based on a Prey vs the Wild Snake Epicrates cenchria crassus Confrontation Paradigm

PubMed Central

Uribe-Mariño, Andrés; Francisco, Audrey; Castiblanco-Urbina, Maria Angélica; Twardowschy, André; Salgado-Rohner, Carlos José; Crippa, José Alexandre S; Hallak, Jaime Eduardo Cecílio; Zuardi, Antônio Waldo; Coimbra, Norberto Cysne

2012-01-01

Several pharmacological targets have been proposed as modulators of panic-like reactions. However, interest should be given to other potential therapeutic neurochemical agents. Recent attention has been given to the potential anxiolytic properties of cannabidiol, because of its complex actions on the endocannabinoid system together with its effects on other neurotransmitter systems. The aim of this study was to investigate the effects of cannabidiol on innate fear-related behaviors evoked by a prey vs predator paradigm. Male Swiss mice were submitted to habituation in an arena containing a burrow and subsequently pre-treated with intraperitoneal administrations of vehicle or cannabidiol. A constrictor snake was placed inside the arena, and defensive and non-defensive behaviors were recorded. Cannabidiol caused a clear anti-aversive effect, decreasing explosive escape and defensive immobility behaviors outside and inside the burrow. These results show that cannabidiol modulates defensive behaviors evoked by the presence of threatening stimuli, even in a potentially safe environment following a fear response, suggesting a panicolytic effect. PMID:21918503

Effects of Mental Load and Fatigue on Steady-State Evoked Potential Based Brain Computer Interface Tasks: A Comparison of Periodic Flickering and Motion-Reversal Based Visual Attention.

PubMed

Xie, Jun; Xu, Guanghua; Wang, Jing; Li, Min; Han, Chengcheng; Jia, Yaguang

Steady-state visual evoked potentials (SSVEP) based paradigm is a conventional BCI method with the advantages of high information transfer rate, high tolerance to artifacts and the robust performance across users. But the occurrence of mental load and fatigue when users stare at flickering stimuli is a critical problem in implementation of SSVEP-based BCIs. Based on electroencephalography (EEG) power indices α, θ, θ + α, ratio index θ/α and response properties of amplitude and SNR, this study quantitatively evaluated the mental load and fatigue in both of conventional flickering and the novel motion-reversal visual attention tasks. Results over nine subjects revealed significant mental load alleviation in motion-reversal task rather than flickering task. The interaction between factors of "stimulation type" and "fatigue level" also illustrated the motion-reversal stimulation as a superior anti-fatigue solution for long-term BCI operation. Taken together, our work provided an objective method favorable for the design of more practically applicable steady-state evoked potential based BCIs.

High frequency oscillations evoked by peripheral magnetic stimulation.

PubMed

Biller, S; Simon, L; Fiedler, P; Strohmeier, D; Haueisen, J

2011-01-01

The analysis of somatosensory evoked potentials (SEP) and / or fields (SEF) is a well-established and important tool for investigating the functioning of the peripheral and central human nervous system. A standard technique to evoke SEPs / SEFs is the stimulation of the median nerve by using a bipolar electrical stimulus. We aim at an alternative stimulation technique enabling stimulation of deep nerve structures while reducing patient stress and error susceptibility. In the current study, we apply a commercial transcranial magnetic stimulation system for peripheral magnetic stimulation of the median nerve. We compare the results of simultaneously recorded EEG signals to prove applicability of our technique to evoke SEPs including low frequency components (LFC) as well as high frequency oscillations (HFO). Therefore, we compare amplitude, latency and time-frequency characteristics of the SEP of 14 healthy volunteers after electric and magnetic stimulation. Both low frequency components and high frequency oscillations were detected. The HFOs were superimposed onto the primary cortical response N20. Statistical analysis revealed significantly lower amplitudes and increased latencies for LFC and HFO components after magnetic stimulation. The differences indicate the inability of magnetic stimulation to elicit supramaximal responses. A psycho-perceptual evaluation showed that magnetic stimulation was less unpleasant for 12 out of the 14 volunteers. In conclusion, we showed that LFC and HFO components related to median nerve stimulation can be evoked by peripheral magnetic stimulation.

Pharmacology of Bradykinin-Evoked Coughing in Guinea Pigs

PubMed Central

Hewitt, Matthew M.; Adams, Gregory; Mazzone, Stuart B.; Mori, Nanako; Yu, Li

2016-01-01

Bradykinin has been implicated as a mediator of the acute pathophysiological and inflammatory consequences of respiratory tract infections and in exacerbations of chronic diseases such as asthma. Bradykinin may also be a trigger for the coughing associated with these and other conditions. We have thus set out to evaluate the pharmacology of bradykinin-evoked coughing in guinea pigs. When inhaled, bradykinin induced paroxysmal coughing that was abolished by the bradykinin B2 receptor antagonist HOE 140. These cough responses rapidly desensitized, consistent with reports of B2 receptor desensitization. Bradykinin-evoked cough was potentiated by inhibition of both neutral endopeptidase and angiotensin-converting enzyme (with thiorphan and captopril, respectively), but was largely unaffected by muscarinic or thromboxane receptor blockade (atropine and ICI 192605), cyclooxygenase, or nitric oxide synthase inhibition (meclofenamic acid and NG-nitro-L-arginine). Calcium influx studies in bronchopulmonary vagal afferent neurons dissociated from vagal sensory ganglia indicated that the tachykinin-containing C-fibers arising from the jugular ganglia mediate bradykinin-evoked coughing. Also implicating the jugular C-fibers was the observation that simultaneous blockade of neurokinin2 (NK2; SR48968) and NK3 (SR142801 or SB223412) receptors nearly abolished the bradykinin-evoked cough responses. The data suggest that bradykinin induces coughing in guinea pigs by activating B2 receptors on bronchopulmonary C-fibers. We speculate that therapeutics targeting the actions of bradykinin may prove useful in the treatment of cough. PMID:27000801

A Perturbation Based Decomposition of Compound-Evoked Potentials for Characterization of Nerve Fiber Size Distributions.

PubMed

Szlavik, Robert B

2016-02-01

The characterization of peripheral nerve fiber distributions, in terms of diameter or velocity, is of clinical significance because information associated with these distributions can be utilized in the differential diagnosis of peripheral neuropathies. Electro-diagnostic techniques can be applied to the investigation of peripheral neuropathies and can yield valuable diagnostic information while being minimally invasive. Nerve conduction velocity studies are single parameter tests that yield no detailed information regarding the characteristics of the population of nerve fibers that contribute to the compound-evoked potential. Decomposition of the compound-evoked potential, such that the velocity or diameter distribution of the contributing nerve fibers may be determined, is necessary if information regarding the population of contributing nerve fibers is to be ascertained from the electro-diagnostic study. In this work, a perturbation-based decomposition of compound-evoked potentials is proposed that facilitates determination of the fiber diameter distribution associated with the compound-evoked potential. The decomposition is based on representing the single fiber-evoked potential, associated with each diameter class, as being perturbed by contributions, of varying degree, from all the other diameter class single fiber-evoked potentials. The resultant estimator of the contributing nerve fiber diameter distribution is valid for relatively large separations in diameter classes. It is also useful in situations where the separation between diameter classes is small and the concomitant single fiber-evoked potentials are not orthogonal.

Pulsed laser versus electrical energy for peripheral nerve stimulation

PubMed Central

Wells, Jonathon; Konrad, Peter; Kao, Chris; Jansen, E. Duco; Mahadevan-Jansen, Anita

2010-01-01

Transient optical neural stimulation has previously been shown to elicit highly controlled, artifact-free potentials within the nervous system in a non-contact fashion without resulting in damage to tissue. This paper presents the physiologic validity of elicited nerve and muscle potentials from pulsed laser induced stimulation of the peripheral nerve in a comparative study with the standard method of electrically evoked potentials. Herein, the fundamental physical properties underlying the two techniques are contrasted. Key laser parameters for efficient optical stimulation of the peripheral nerve are detailed. Strength response curves are shown to be linear for each stimulation modality, although fewer axons can be recruited with optically evoked potentials. Results compare the relative transient energy requirements for stimulation using each technique and demonstrate that optical methods can selectively excite functional nerve stimulation. Adjacent stimulation and recording of compound nerve potentials in their entirety from optical and electrical stimulation are presented, with optical responses shown to be free of any stimulation artifact. Thus, use of a pulsed laser exhibits some advantages when compared to standard electrical means for excitation of muscle potentials in the peripheral nerve in the research domain and possibly for clinical diagnostics in the future. PMID:17537515

Early-Stage Visual Processing and Cortical Amplification Deficits in Schizophrenia

PubMed Central

Butler, Pamela D.; Zemon, Vance; Schechter, Isaac; Saperstein, Alice M.; Hoptman, Matthew J.; Lim, Kelvin O.; Revheim, Nadine; Silipo, Gail; Javitt, Daniel C.

2005-01-01

Background Patients with schizophrenia show deficits in early-stage visual processing, potentially reflecting dysfunction of the magnocellular visual pathway. The magnocellular system operates normally in a nonlinear amplification mode mediated by glutamatergic (N-methyl-d-aspartate) receptors. Investigating magnocellular dysfunction in schizophrenia therefore permits evaluation of underlying etiologic hypotheses. Objectives To evaluate magnocellular dysfunction in schizophrenia, relative to known neurochemical and neuroanatomical substrates, and to examine relationships between electrophysiological and behavioral measures of visual pathway dysfunction and relationships with higher cognitive deficits. Design, Setting, and Participants Between-group study at an inpatient state psychiatric hospital and out-patient county psychiatric facilities. Thirty-three patients met DSM-IV criteria for schizophrenia or schizoaffective disorder, and 21 nonpsychiatric volunteers of similar ages composed the control group. Main Outcome Measures (1) Magnocellular and parvocellular evoked potentials, analyzed using nonlinear (Michaelis-Menten) and linear contrast gain approaches; (2) behavioral contrast sensitivity measures; (3) white matter integrity; (4) visual and nonvisual neuropsychological measures, and (5) clinical symptom and community functioning measures. Results Patients generated evoked potentials that were significantly reduced in response to magnocellular-biased, but not parvocellular-biased, stimuli (P=.001). Michaelis-Menten analyses demonstrated reduced contrast gain of the magnocellular system (P=.001). Patients showed decreased contrast sensitivity to magnocellular-biased stimuli (P<.001). Evoked potential deficits were significantly related to decreased white matter integrity in the optic radiations (P<.03). Evoked potential deficits predicted impaired contrast sensitivity (P=.002), which was in turn related to deficits in complex visual processing (P≤.04). Both evoked potential (P≤.04) and contrast sensitivity (P=.01) measures significantly predicted community functioning. Conclusions These findings confirm the existence of early-stage visual processing dysfunction in schizophrenia and provide the first evidence that such deficits are due to decreased nonlinear signal amplification, consistent with glutamatergic theories. Neuroimaging studies support the hypothesis of dysfunction within low-level visual pathways involving thalamocortical radiations. Deficits in early-stage visual processing significantly predict higher cognitive deficits. PMID:15867102

Conductance changes associated with the secretory potential in the cockroach salivary gland.

PubMed

Ginsborg, B L; House, C R; Silinsky, E M

1974-02-01

1. Conductance changes in the acini of the cockroach salivary gland have been examined during nerve stimulation by means of two intracellular electrodes placed in the same acinus, the first electrode being used for recording membrane potential and the second for current injection.2. The transient hyperpolarization (secretory potential) in the acinus evoked by nerve stimuli is accompanied by a rise in membrane conductance. The conductance, however, remains high for a longer period than that of the response.3. Applying the analysis of Trautwein & Dudel (1958) to the secretory potentials recorded in the acinus (assumed to behave electrically like a single cell) gives estimates of the ;transmitter equilibrium potential'. The values indicate that the neurotransmitter increases the membrane potassium conductance.4. The hyperpolarization of the acinus evoked by 10(-6)M dopamine in the bathing fluid is also associated with an increase in membrane potassium conductance.

Functional ligand-gated purinergic receptors (P2X) in rat vestibular ganglion neurons.

PubMed

Ito, Ken; Chihara, Yasuhiro; Iwasaki, Shinichi; Komuta, Yukari; Sugasawa, Masashi; Sahara, Yoshinori

2010-08-01

The expression of purinergic receptors (P2X) on rat vestibular ganglion neurons (VGNs) was examined using whole-cell patch-clamp recordings. An application of adenosine 5'-triphosphate (ATP; 100microM) evoked inward currents in VGNs at a holding potential of -60mV. The decay time constant of the ATP-evoked currents was 2-4s, which is in between the values for rapidly desensitizing subgroups (P2X1 and P2X3) and slowly desensitizing subgroups (P2X2, P2X4, etc.), suggesting the heterogeneous expression of P2X receptors. A dose-response experiment showed an EC(50) of 11.0microM and a Hill's coefficient of 0.82. Suramin (100microM) reversibly inhibited the ATP-evoked inward currents. Alpha, beta-methylene ATP (100microM), a P2X-specific agonist, also evoked inward currents but less extensively than ATP. An application of adenosine 5'-dihosphate (ADP; 100microM) evoked similar, but much smaller, currents. The current-voltage relationship of the ATP-evoked conductance showed pronounced inward rectification with a reversal potential more positive than 0mV, suggesting non-selective cation conductance. However, the channel was not permeable to a large cation (N-methyl-d-glucamine) and acidification (pH 6.3) had little effect on the ATP-evoked conductance. RT-PCR confirmed the expression of five subtypes (P2X2-P2X6) in VGNs. The physiological role of P2X receptors includes the modulation of excitability at the synapses between hair cells and dendrites and/or trophic support (or also neuromodulation) from supporting cells surrounding the VGNs. Copyright 2010 Elsevier B.V. All rights reserved.

Parvalbumin interneuron mediated feedforward inhibition controls signal output in the deep layers of the perirhinal‐entorhinal cortex

PubMed Central

Willems, Janske G. P.; Wadman, Wytse J.

2018-01-01

Abstract The perirhinal (PER) and lateral entorhinal (LEC) cortex form an anatomical link between the neocortex and the hippocampus. However, neocortical activity is transmitted through the PER and LEC to the hippocampus with a low probability, suggesting the involvement of the inhibitory network. This study explored the role of interneuron mediated inhibition, activated by electrical stimulation in the agranular insular cortex (AiP), in the deep layers of the PER and LEC. Activated synaptic input by AiP stimulation rarely evoked action potentials in the PER‐LEC deep layer excitatory principal neurons, most probably because the evoked synaptic response consisted of a small excitatory and large inhibitory conductance. Furthermore, parvalbumin positive (PV) interneurons—a subset of interneurons projecting onto the axo‐somatic region of principal neurons—received synaptic input earlier than principal neurons, suggesting recruitment of feedforward inhibition. This synaptic input in PV interneurons evoked varying trains of action potentials, explaining the fast rising, long lasting synaptic inhibition received by deep layer principal neurons. Altogether, the excitatory input from the AiP onto deep layer principal neurons is overruled by strong feedforward inhibition. PV interneurons, with their fast, extensive stimulus‐evoked firing, are able to deliver this fast evoked inhibition in principal neurons. This indicates an essential role for PV interneurons in the gating mechanism of the PER‐LEC network. PMID:29341361

An N-methyl-D-aspartate receptor-independent excitatory action of partial reduction of extracellular [Mg2+] in CA1-region of rat hippocampal slices.

PubMed

Hamon, B; Stanton, P K; Heinemann, U

1987-03-31

Partial reduction of [Mg2+]o from 2 to 1 mM markedly enhanced neuronal responses evoked by Schaffer collateral-commissural fiber stimulation in the CA1-region of rat hippocampal slices. The amplitude of extracellular population potentials recorded in the CA1-pyramidal cell layer and maximum dV/dt of extracellular population EPSP's recorded in the CA1-pyramidal apical dendritic layer were both increased. However, unlike findings from slices where Mg2+ was completely removed from the bathing medium, there was no spontaneous or evoked epileptiform activity, and the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (2-APV) did not antagonize the enhancement of evoked responses. These results indicate that, in addition to the participation of NMDA receptors in the epileptiform activity observed when Mg2+ is completely removed from the bathing medium, there is also an NMDA receptor-independent excitatory action of partial reduction of [Mg2+]o in hippocampal slices.

Ocular vestibular evoked myogenic potential elicited from binaural air-conducted stimulations: clinical feasibility in patients with peripheral vestibular dysfunction.

PubMed

Iwasaki, Shinichi; Egami, Naoya; Inoue, Aki; Kinoshita, Makoto; Fujimoto, Chisato; Murofushi, Toshihisa; Yamasoba, Tatsuya

2013-07-01

Ocular vestibular evoked myogenic potentials (oVEMPs) to binaural air-conducted stimulation (ACS) may provide a convenient way of assessing the crossed vestibulo-ocular reflex in patients with vestibular dysfunction as well as in healthy subjects. To investigate the clinical feasibility of using oVEMPs in response to binaural ACS to assess normal subjects and patients with vestibular dysfunction. The study investigated 24 normal subjects (14 men and 10 women, aged from 23 to 60 years) and 14 patients with unilateral peripheral vestibular dysfunction. Each subject underwent oVEMP testing in response to monaural ACS and binaural ACS (500 Hz tone burst, 135 dBSPL). In normal subjects, bilateral oVEMPs were elicited in 75% of subjects in response to monaural ACS and in 91% in response to binaural ACS. Asymmetry ratios (ARs) of the responses to binaural ACS were significantly smaller than those of the responses to monaural ACS (p < 0.01). In patients with unilateral vestibular dysfunction, there were no significant differences in the amplitude, latency, or AR of the responses between monaural and binaural ACS. Approximately 30% of patients showed reduced ARs to binaural ACS relative to monaural ACS, primarily due to contamination by uncrossed responses elicited in healthy ears.

Optical imaging of neural and hemodynamic brain activity

NASA Astrophysics Data System (ADS)

Schei, Jennifer Lynn

Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic sleep disturbances could push the vasculature to critical limits, leading to metabolic deficit and the potential for tissue trauma.

Identification of spinal circuits involved in touch-evoked dynamic mechanical pain

PubMed Central

Cheng, Longzhen; Duan, Bo; Huang, Tianwen; Zhang, Yan; Chen, Yangyang; Britz, Olivier; Garcia-Campmany, Lidia; Ren, Xiangyu; Vong, Linh; Lowell, Bradford B.; Goulding, Martyn; Wang, Yun; Ma, Qiufu

2017-01-01

Mechanical hypersensitivity is a debilitating symptom associated with millions of chronic pain patients. It exists in distinct forms, including brush-evoked dynamic and filament-evoked punctate. Here we report that dynamic mechanical hypersensitivity induced by nerve injury or inflammation was compromised in mice with ablation of spinal VT3Lbx1 neurons defined by coexpression of VGLUT3Cre and Lbx1Flpo, as indicated by the loss of brush-evoked nocifensive responses and conditional place aversion. Electrophysiological recordings show that VT3Lbx1 neurons form morphine-resistant polysynaptic pathways relaying inputs from low-threshold Aβ mechanoreceptors to lamina I output neurons. Meanwhile, the subset of somatostatin (SOM) lineage neurons preserved in VT3Lbx1 neuron-ablated mice is largely sufficient to mediate von Frey filament-evoked punctate mechanical hypersensitivity, including both morphine-sensitive and morphine-resistant forms. Furthermore, acute silencing of VT3Lbx1 neurons attenuated pre-established dynamic mechanical hypersensitivity induced by nerve injury, suggesting these neurons as a potential cellular target for treating this form of neuropathic pain. PMID:28436981

Intraoperative changes in transcranial motor evoked potentials and somatosensory evoked potentials predicting outcome in children with intramedullary spinal cord tumors.

PubMed

Cheng, Jason S; Ivan, Michael E; Stapleton, Christopher J; Quinones-Hinojosa, Alfredo; Gupta, Nalin; Auguste, Kurtis I

2014-06-01

Intraoperative dorsal column mapping, transcranial motor evoked potentials (TcMEPs), and somatosensory evoked potentials (SSEPs) have been used in adults to assist with the resection of intramedullary spinal cord tumors (IMSCTs) and to predict postoperative motor deficits. The authors sought to determine whether changes in MEP and SSEP waveforms would similarly predict postoperative motor deficits in children. The authors reviewed charts and intraoperative records for children who had undergone resection for IMSCTs as well as dorsal column mapping and TcMEP and SSEP monitoring. Motor evoked potential data were supplemented with electromyography data obtained using a Kartush microstimulator (Medtronic Inc.). Motor strength was graded using the Medical Research Council (MRC) scale during the preoperative, immediate postoperative, and follow-up periods. Reductions in SSEPs were documented after mechanical traction, in response to maneuvers with the cavitational ultrasonic surgical aspirator (CUSA), or both. Data from 12 patients were analyzed. Three lesions were encountered in the cervical and 7 in the thoracic spinal cord. Two patients had lesions of the cervicomedullary junction and upper spinal cord. Intraoperative MEP changes were noted in half of the patients. In these cases, normal polyphasic signals converted to biphasic signals, and these changes correlated with a loss of 1-2 grades in motor strength. One patient lost MEP signals completely and recovered strength to MRC Grade 4/5. The 2 patients with high cervical lesions showed neither intraoperative MEP changes nor motor deficits postoperatively. Dorsal columns were mapped in 7 patients, and the midline was determined accurately in all 7. Somatosensory evoked potentials were decreased in 7 patients. Two patients each had 2 SSEP decreases in response to traction intraoperatively but had no new sensory findings postoperatively. Another 2 patients had 3 traction-related SSEP decreases intraoperatively, and both had new postoperative sensory deficits that resolved. One additional patient had a CUSA-related SSEP decrease intraoperatively, which resolved postoperatively, and the last patient had 3 traction-related sensory deficits and a CUSA-related sensory deficit postoperatively, none of which resolved. Intraoperative TcMEPs and SSEPs can predict the degree of postoperative motor deficit in pediatric patients undergoing IMSCT resection. This technique, combined with dorsal column mapping, is particularly useful in resecting lesions of the upper cervical cord, which are generally considered to be high risk in this population. Furthermore, the spinal cord appears to be less tolerant of repeated intraoperative SSEP decreases, with 3 successive insults most likely to yield postoperative sensory deficits. Changes in TcMEPs and SSEP waveforms can signal the need to guard against excessive manipulation thereby increasing the safety of tumor resection.

Music matters: preattentive musicality of the human brain.

PubMed

Koelsch, Stefan; Schroger, Erich; Gunter, Thomas C

2002-01-01

During listening to a musical piece, unexpected harmonies may evoke brain responses that are reflected electrically as an early right anterior negativity (ERAN) and a late frontal negativity (N5). In the present study we demonstrate that these components of the event-related potential can be evoked preattentively, that is, even when a musical stimulus is ignored. Both ERAN and N5 differed in amplitude as a function of music-theoretical principles. Participants had no special musical expertise; results thus provide evidence for an automatic processing of musical information in onmusicians."

Prostaglandin potentiates 5-HT responses in stomach and ileum innervating visceral afferent sensory neurons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Sojin; Jin, Zhenhua; Lee, Goeun

2015-01-02

Highlights: • Prostaglandin E2 (PGE{sub 2}) effect was tested on visceral afferent neurons. • PGE{sub 2} did not evoke response but potentiated serotonin (5-HT) currents up to 167%. • PGE{sub 2}-induced potentiation was blocked by E-prostanoid type 4 receptors antagonist. • PGE{sub 2} effect on 5-HT response was also blocked by protein kinase A inhibitor KT5720. • Thus, PGE{sub 2} modulate visceral afferent neurons via synergistic signaling with 5-HT. - Abstract: Gastrointestinal disorder is a common symptom induced by diverse pathophysiological conditions that include food tolerance, chemotherapy, and irradiation for therapy. Prostaglandin E{sub 2} (PGE{sub 2}) level increase was oftenmore » reported during gastrointestinal disorder and prostaglandin synthetase inhibitors has been used for ameliorate the symptoms. Exogenous administration of PGE{sub 2} induces gastrointestinal disorder, however, the mechanism of action is not known. Therefore, we tested PGE{sub 2} effect on visceral afferent sensory neurons of the rat. Interestingly, PGE{sub 2} itself did not evoked any response but enhanced serotonin (5-HT)-evoked currents up to 167% of the control level. The augmented 5-HT responses were completely inhibited by a 5-HT type 3 receptor antagonist, ondansetron. The PGE{sub 2}-induced potentiation were blocked by a selective E-prostanoid type4 (EP{sub 4}) receptors antagonist, L-161,982, but type1 and 2 receptor antagonist AH6809 has no effect. A membrane permeable protein kinase A (PKA) inhibitor, KT5720 also inhibited PGE{sub 2} effects. PGE{sub 2} induced 5-HT current augmentation was observed on 15% and 21% of the stomach and ileum projecting neurons, respectively. Current results suggest a synergistic signaling in visceral afferent neurons underlying gastrointestinal disorder involving PGE{sub 2} potentiation of 5-HT currents. Our findings may open a possibility for screen a new type drugs with lower side effects than currently using steroidal prostaglandin synthetase inhibitors by selectively targeting EP{sub 4} receptor/PKA pathway without interrupt prostaglandin synthesis.« less

Induced and evoked neural correlates of orientation selectivity in human visual cortex.

PubMed

Koelewijn, Loes; Dumont, Julie R; Muthukumaraswamy, Suresh D; Rich, Anina N; Singh, Krish D

2011-02-14

Orientation discrimination is much better for patterns oriented along the horizontal or vertical (cardinal) axes than for patterns oriented obliquely, but the neural basis for this is not known. Previous animal neurophysiology and human neuroimaging studies have demonstrated only a moderate bias for cardinal versus oblique orientations, with fMRI showing a larger response to cardinals in primary visual cortex (V1) and EEG demonstrating both increased magnitudes and reduced latencies of transient evoked responses. Here, using MEG, we localised and characterised induced gamma and transient evoked responses to stationary circular grating patches of three orientations (0, 45, and 90° from vertical). Surprisingly, we found that the sustained gamma response was larger for oblique, compared to cardinal, stimuli. This "inverse oblique effect" was also observed in the earliest (80 ms) evoked response, whereas later responses (120 ms) showed a trend towards the reverse, "classic", oblique response. Source localisation demonstrated that the sustained gamma and early evoked responses were localised to medial visual cortex, whilst the later evoked responses came from both this early visual area and a source in a more inferolateral extrastriate region. These results suggest that (1) the early evoked and sustained gamma responses manifest the initial tuning of V1 neurons, with the stronger response to oblique stimuli possibly reflecting increased tuning widths for these orientations, and (2) the classic behavioural oblique effect is mediated by an extrastriate cortical area and may also implicate feedback from extrastriate to primary visual cortex. Copyright © 2010 Elsevier Inc. All rights reserved.

Single-trial laser-evoked potentials feature extraction for prediction of pain perception.

PubMed

Huang, Gan; Xiao, Ping; Hu, Li; Hung, Yeung Sam; Zhang, Zhiguo

2013-01-01

Pain is a highly subjective experience, and the availability of an objective assessment of pain perception would be of great importance for both basic and clinical applications. The objective of the present study is to develop a novel approach to extract pain-related features from single-trial laser-evoked potentials (LEPs) for classification of pain perception. The single-trial LEP feature extraction approach combines a spatial filtering using common spatial pattern (CSP) and a multiple linear regression (MLR). The CSP method is effective in separating laser-evoked EEG response from ongoing EEG activity, while MLR is capable of automatically estimating the amplitudes and latencies of N2 and P2 from single-trial LEP waveforms. The extracted single-trial LEP features are used in a Naïve Bayes classifier to classify different levels of pain perceived by the subjects. The experimental results show that the proposed single-trial LEP feature extraction approach can effectively extract pain-related LEP features for achieving high classification accuracy.

[Effects of intermittent hypoxia on the responses of genioglossus motor cortex to transcranial magnetic stimulation in rats].

PubMed

Li, Ting; Wang, Wei; Kong, De-lei; Su, Jiao; Kang, Jian

2012-04-01

To explore the influence of intermittent hypoxia on the responses of genioglossus motor cortex to transcranial magnetic stimulation. Male Sprague-Dawley rats were randomly divided into a control group and a chronic intermittent hypoxia group. Transcranial magnetic stimulation was applied in genioglossus motor cortex of the 2 groups. The responses of transcranial magnetic stimulation were recorded and analyzed by single factor analysis of variance. The anterolateral area provided an optimal motor evoked potential response to transcranial magnetic stimulation in the genioglossus motor cortex of the rats. Genioglossus motor evoked potential latency and amplitude were significantly modified by intermittent hypoxic exposure, with a significant decrease in latency (F = 3.294, P < 0.01) at the 1st day [(4.90 ± 0.54) ms] and the 14th day [(4.64 ± 1.71) ms], and an increase in amplitude (F = 1.905, P < 0.05) at the 1st day [(2.28 ± 0.57) mV] and the 7th day [(1.89 ± 0.20) mV]. Intermittent hypoxia could increase the transcranial magnetic stimulation response of genioglossus motor cortex in rats.

Effect of head circumference on parameters of pattern reversal visual evoked potential in healthy adults of central India.

PubMed

Kothari, R; Singh, R; Singh, S; Bokariya, P

2012-06-01

Visual evoked response testing has been one of the most exciting clinical tools to be developed from neurophysiologic research in recent years and has provided us with an objective method of identifying abnormalities of the afferent visual pathways. Investigation were carried out to see whether the head circumference influence the pattern reversal visual evoked potential (PRVEP) parameters. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings in 400 eyes of 200 normal subjects. Two hundred fourty eight eyes were males and 152 eyes were from 76 female subjects recruited from the Central Indian population in the age range of 40-79 years. Visual evoked potential (VEP) recordings were performed in accordance to the standardized methodology of International Federation of Clinical Neurophysiology (IFCN) Committee Recommendations and International Society for Clinical Electrophysiology of Vision (ISCEV) Guidelines and montages were kept as per 10-20 International System of EEG Electrode placements. The stimulus configuration in this study consisted of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on a VEP Monitor by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). VEP latencies, duration and amplitude were measured in all subjects and the data were analyzed. The correlation of all the electrophysiological parameters with head circumference was evaluated by Pearson's correlation co-efficient (r) and its statistical significance was evaluated. The prediction equations for all the VEP parameters with respect to head circumference were derived. We found a positive correlation of P 100 latency and N 155 latency with mean head circumference, while a highly significant negative correlation were noted of P 100 amplitude with head circumference. N 70 latency was significantly correlated with head circumference. P 100 duration showed in negative correlation with head circumference. These findings suggest that VEP latencies, duration and amplitude are influenced by the head circumference of the individual in a sample of healthy subjects and head circumference can be a useful predictor of VEP peak latencies, amplitude and duration.

Combined evoked potentials in co-occuring attention deficit hyperactivity disorder and epilepsy.

PubMed

Major, Zoltán Zsigmond

2011-07-30

Evoked potentials, both stimulus related and event related, show disturbances in attention deficit-hyperactivity disorder and epilepsies, too. This study was designed to evaluate if these potentials are characteristically influenced by the presence of the two diseases, individually, and in the case of co-occurrence. Forty children were included, and four groups were formed, control group, ADHD group, epilepsy group and a group with the comorbidity of epilepsy and ADHD. Epilepsy patients were under proper antiepileptic treatment; ADHD patients were free of specific therapy. Brainstem auditory evoked potentials, visual evoked potentials and auditory P300 evaluation were performed. The latency of the P100 and N135 visual evoked potential components was significantly extended by the presence of epilepsy. If ADHD was concomitantly present, this effect was attenuated. Brainstem auditory evoked potential components were prolonged in the presence of the comorbidity, considering the waves elicited in the brainstem. P300 latencies were prolonged by the presence of co-occurring ADHD and epilepsy. Feedback parameters showed overall reduction of the tested cognitive performances in the ADHD group. Disturbances produced by the presence of ADHD-epilepsy comorbidity reveal hypothetically a linked physiopathological path for both diseases, and offers an approach with possible diagnostic importance, combined evoked potential recordings.

Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

PubMed Central

Ji, Yiming; Meng, Bin; Yuan, Chenxi; Yang, Huilin; Zou, Jun

2013-01-01

It remains unclear whether spinal cord ischemia-reperfusion injury caused by ischemia and other non-mechanical factors can be monitored by somatosensory evoked potentials. Therefore, we monitored spinal cord ischemia-reperfusion injury in rabbits using somatosensory evoked potential detection technology. The results showed that the somatosensory evoked potential latency was significantly prolonged and the amplitude significantly reduced until it disappeared during the period of spinal cord ischemia. After reperfusion for 30–180 minutes, the amplitude and latency began to gradually recover; at 360 minutes of reperfusion, the latency showed no significant difference compared with the pre-ischemic value, while the somatosensory evoked potential amplitude in-creased, and severe hindlimb motor dysfunctions were detected. Experimental findings suggest that changes in somatosensory evoked potential latency can reflect the degree of spinal cord ischemic injury, while the amplitude variations are indicators of the late spinal cord reperfusion injury, which provide evidence for the assessment of limb motor function and avoid iatrogenic spinal cord injury. PMID:25206629

The Role of Auditory Evoked Potentials in the Context of Cochlear Implant Provision.

PubMed

Hoth, Sebastian; Dziemba, Oliver Christian

2017-12-01

: Auditory evoked potentials (AEP) are highly demanded during the whole process of equipping patients with cochlear implants (CI). They play an essential role in preoperative diagnostics, intraoperative testing, and postoperative monitoring of auditory performance and success. The versatility of AEP's is essentially enhanced by their property to be evokable by acoustic as well as electric stimuli. Thus, the electric responses of the auditory system following acoustic stimulation and recorded by the conventional surface technique as well as by transtympanic derivation from the promontory (Electrocochleography [ECochG]) are used for the quantitative determination of hearing loss and, additionally, electrically evoked compound actions potentials (ECAP) can be recorded with the intracochlear electrodes of the implant just adjacent to the stimulation electrode to check the functional integrity of the device and its coupling to the auditory system. The profile of ECAP thresholds is used as basis for speech processor fitting, the spread of excitation (SOE) allows the identification of electrode mislocations such as array foldover, and recovery functions may serve to optimize stimulus pulse rate. These techniques as well as those relying on scalp surface activity originating in the brainstem or the auditory cortex accompany the CI recipient during its whole life span and they offer valuable insights into functioning and possible adverse effects of the CI for clinical and scientific purposes.

Neuronal current magnetic resonance imaging of evoked potentials and neural oscillations

NASA Astrophysics Data System (ADS)

Jiang, Xia

Despite its great success, the current functional magnetic resonance imaging (MRI) technique relies on changes in cerebral hemodynamic parameters to infer the underlying neural activities, and as a result is limited in its spatial and temporal resolutions. In this dissertation, we discuss the feasibility of neuronal current MRI (nc-MRI), a novel technique in which the small magnetic field changes caused by neuronal electrical activities are directly measured by MRI. Two studies are described. In the first study, we investigated the feasibility of detecting the magnetic field produced by sensory evoked potentials. To eliminate the blood-oxygen-level-dependent (BOLD) effect on the MRI signal, which confounded most previous studies, an octopus visual system model was developed, which, for the first time, allowed for an in vivo investigation of nc-MRI in a BOLD-free environment. Electrophysiological responses were measured in the octopus retina and optical lobe to guide the nc-MRI acquisition. Our results indicated that no nc-MRI signal change related to neuronal activation could be detected at 0.2°/0.2% threshold for signal phase/magnitude respectively, while robust electrophysiological responses were recorded. In the second study, we discuss the feasibility of detecting neural oscillations with MRI, Based on previous studies, a novel approach was proposed in which an external oscillatory field was exploited as the excitation pulse under a spin-locked condition. This approach has the advantages of increased sensitivity and lowered physiological noise. Successful detection of sub-nanotesla field was demonstrated in phantom. Our results suggest that evoked potentials are too weak for nc-MRI detection with the current hardware, and that previous positive findings were likely due to hemodynamic confounders. On the other hand, oscillatory magnetic field can be efficiently detected in phantom. Given the stronger equivalent current dipoles produced by neural oscillations compared to evoked potentials, they might be a more promising candidate for future nc-MRI studies.

[Communication and auditory behavior obtained by auditory evoked potentials in mammals, birds, amphibians, and reptiles].

PubMed

Arch-Tirado, Emilio; Collado-Corona, Miguel Angel; Morales-Martínez, José de Jesús

2004-01-01

amphibians, Frog catesbiana (frog bull, 30 animals); reptiles, Sceloporus torcuatus (common small lizard, 22 animals); birds: Columba livia (common dove, 20 animals), and mammals, Cavia porcellus, (guinea pig, 20 animals). With regard to lodging, all animals were maintained at the Institute of Human Communication Disorders, were fed with special food for each species, and had water available ad libitum. Regarding procedure, for carrying out analysis of auditory evoked potentials of brain stem SPL amphibians, birds, and mammals were anesthetized with ketamine 20, 25, and 50 mg/kg, by injection. Reptiles were anesthetized by freezing (6 degrees C). Study subjects had needle electrodes placed in an imaginary line on the half sagittal line between both ears and eyes, behind right ear, and behind left ear. Stimulation was carried out inside a no noise site by means of a horn in free field. The sign was filtered at between 100 and 3,000 Hz and analyzed in a computer for provoked potentials (Racia APE 78). In data shown by amphibians, wave-evoked responses showed greater latency than those of the other species. In reptiles, latency was observed as reduced in comparison with amphibians. In the case of birds, lesser latency values were observed, while in the case of guinea pigs latencies were greater than those of doves but they were stimulated by 10 dB, which demonstrated best auditory threshold in the four studied species. Last, it was corroborated that as the auditory threshold of each species it descends conforms to it advances in the phylogenetic scale. Beginning with these registrations, we care able to say that response for evoked brain stem potential showed to be more complex and lesser values of absolute latency as we advance along the phylogenetic scale; thus, the opposing auditory threshold is better agreement with regard to the phylogenetic scale among studied species. These data indicated to us that seeking of auditory information is more complex in more evolved species.

Substance P is a functional neurotransmitter in the rat parotid gland.

PubMed

Gallacher, D V

1983-09-01

The technique of electrical field stimulation was employed to stimulate the intrinsic nerves of isolated rat parotid gland fragments. Responses to field stimulation were recorded as changes in enzyme secretion (amylase release), radiolabelled ion fluxes (86Rb efflux) and electrophysiological effects (changes in acinar cell membrane potential and input resistance). All effects of field stimulation were abolished by the neurotoxin, tetrodotoxin (TTX). Selective use of pharmacological antagonists revealed that both the sympathetic and parasympathetic nerves to this tissue were being excited by field stimulation. Importantly a significant component of the response to field stimulation persisted in the presence of combined autonomic receptor blockade by atropine, phentolamine and propranolol, i.e. due to release of a non-cholinergic, non-adrenergic neurotransmitter. The non-cholinergic, non-adrenergic neurotransmitter evoked amylase release, 86Rb efflux and electrophysiological effects seen as changes in acinar cell membrane potential and conductance, i.e. stimulus-permeability coupled. Two biologically active peptides, substance P (SP) and vasoactive intestinal polypeptide (VIP) were shown to evoke amylase release in the presence of combined autonomic blockade. VIP however did not evoke any increase in 86Rb efflux, i.e. not stimulus-permeability coupled. All the effects of the non-cholinergic, non-adrenergic transmitter were mimicked by substance P which evokes 86Rb efflux and electrophysiological effects in addition to amylase release. The non-cholinergic, non-adrenergic field stimulus effects on amylase release and 86Rb efflux were abolished or markedly attenuated in tissues which had been desensitized by prior exposure to exogenous substance P. In the presence of VIP, however, the non-cholinergic, non-adrenergic effects persisted and were apparently potentiated. Acute application of the neurotoxin capsaicin first stimulated a transient release of amylase and subsequently abolished the non-cholinergic, non-adrenergic field stimulus-evoked enzyme release. The putative substance P antagonist, D-Pro2, D-Trp7,9 substance P, reversibly blocked the response to both non-cholinergic, non-adrenergic nerve stimulation and exogenous substance P. It was demonstrated however that prolonged exposure to this antagonist is associated with non-reversible and, importantly, non-specific neurotoxic effects. It is concluded that substance P or a closely related peptide is a functional neurotransmitter in the rat parotid gland.

Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

PubMed

Gordon, K A; Papsin, B C; Harrison, R V

2007-08-01

The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

Sodium-bicarbonate cotransport in retinal Müller (glial) cells of the salamander.

PubMed

Newman, E A

1991-12-01

An electrogenic Na+/HCO3- cotransport system was studied in freshly dissociated Müller cells of the salamander retina. Cotransporter currents were recorded from isolated cells using the whole-cell, voltage-clamp technique following the block of K+ conductance with external Ba2+ and internal Cs+. At constant pHo, an outward current was evoked when extracellular HCO3- concentration was raised by pressure ejecting a HCO3(-)-buffered solution onto the surface of cells bathed in nominally HCO3(-)-free solution. The HCO3(-)-evoked outward current was reduced to 4.4% of control by 0.5 mM DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonate), to 28.8% of control by 2 mM DNDS (4,4'-dinitrostilbene-2,2'-disulfonate), and to 28.4% of control by 2 mM harmaline. Substitution of choline for Na+ in bath and ejection solutions reduced the response to 1.3% of control. Bicarbonate-evoked currents of normal magnitude were recorded when methane sulfonate was substituted for Cl- in bath, ejection, and intracellular solutions. Similarly, an outward current was evoked when extracellular Na+ concentration was raised in the presence of HCO3-. The Na(+)-evoked response was reduced to 16.2% of control by 2 mM DNDS and was abolished by removal of HCO3- from bath and ejection solutions. Taken together, these results (block by stilbenes and harmaline, HCO3- and Na+ dependence, Cl- independence) indicate that salamander Müller cells possess an electrogenic Na+/HCO3- cotransport system. Na+/HCO3- cotransporter sites were localized primarily at the endfoot region of Müller cells. Ejection of HCO3- onto the endfoot evoked outward currents 10 times larger than currents evoked by ejections onto the opposite (distal) end of the cell. The reversal potential of the cotransporter was determined by DNDS block of cotransport current. In the absence of a transmembrane HCO3- gradient, the reversal potential varied systematically as a function of the transmembrane Na+ gradient. The reversal potential was -0.1 mV for a [Na+]o:[Na+]i ratio of 1:1 and -25.2 mV for a Na+ gradient ratio of 7.4:1. Based on these values, the estimated stoichiometry of the cotransporter was 2.80 +/- 0.13:1 (HCO3-:Na+). Possible functions of the glial cell Na+/HCO3- cotransporter, including the regulation of CO2 in the retina and the regulation of cerebral blood flow, are discussed.

Implantable Neural Interfaces for Sharks

DTIC Science & Technology

2007-05-01

technology for recording and stimulating from the auditory and olfactory sensory nervous systems of the awake , swimming nurse shark, G. cirratum (Figures...and awake animals. Finally, evidence exists that microstimulation of the olfactory system could lead to patterned behavioral responses in the...auditory-evoked local field potentials (multi- modal sensory responses) from both anesthetized and awake animals. Figure 1: Pre-operative MR

Cortical Inhibition in Attention Deficit Hyperactivity Disorder: New Insights from the Electroencephalographic Response to Transcranial Magnetic Stimulation

ERIC Educational Resources Information Center

Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M.; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

2012-01-01

Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the…

Moral identity and emotion in athletes.

PubMed

Kavussanu, Maria; Willoughby, Adrian; Ring, Christopher

2012-12-01

The purpose of this study was to investigate the effects of moral identity on physiological responses to affective pictures, namely, the startle blink reflex and pain-related evoked potential. Male (n = 48) and female (n = 46) athletes participating in contact team sports were randomly assigned to either a moral identity group or a non-moral identity group and viewed a series of unpleasant, neutral, and pleasant sport-specific pictures. During picture viewing, a noxious electrocutaneous stimulus was delivered as the startle probe and the startle blink and pain-related evoked potential were measured. Upon completion of physiological measures, participants reviewed the pictures and rated them for valence and arousal. ANOVAs revealed that participants in the moral identity group displayed larger startle blinks and smaller pain-related potentials than did those in the non-moral identity group across all picture valence categories. However, the difference in the magnitude of startle blinks between the moral and non-moral identity groups was larger in response to unpleasant than pleasant and neutral pictures. Our findings suggest that moral identity affects physiological responses to sport-specific affective pictures, thereby providing objective evidence for the link between moral identity and emotion in athletes.

Objective response detection in an electroencephalogram during somatosensory stimulation.

PubMed

Simpson, D M; Tierra-Criollo, C J; Leite, R T; Zayen, E J; Infantosi, A F

2000-06-01

Techniques for objective response detection aim to identify the presence of evoked potentials based purely on statistical principles. They have been shown to be potentially more sensitive than the conventional approach of subjective evaluation by experienced clinicians and could be of great clinical use. Three such techniques to detect changes in an electroencephalogram (EEG) synchronous with the stimuli, namely, magnitude-squared coherence (MSC), the phase-synchrony measure (PSM) and the spectral F test (SFT) were applied to EEG signals of 12 normal subjects under conventional somatosensory pulse stimulation to the tibial nerve. The SFT, which uses only the power spectrum, showed the poorest performance, while the PSM, based only on the phase spectrum, gave results almost as good as those of the MSC, which uses both phase and power spectra. With the latter two techniques, stimulus responses were evident in the frequency range of 20-80 Hz in all subjects after 200 stimuli (5 Hz stimulus frequency), whereas for visual recognition at least 500 stimuli are usually applied. Based on these results and on simulations, the phase-based techniques appear promising for the automated detection and monitoring of somatosensory evoked potentials.

Combining near-infrared spectroscopy with electroencephalography and repetitive transcranial magnetic stimulation

NASA Astrophysics Data System (ADS)

Näsi, Tiina; Kotilahti, Kalle; Mäki, Hanna; Nissilä, Ilkka; Meriläinen, Pekka

2009-07-01

The objective of the study was to assess the usability of a near-infrared spectroscopy (NIRS) device in multimodal measurements. We combined NIRS with electroencephalography (EEG) to record hemodynamic responses and evoked potentials simultaneously, and with transcranial magnetic stimulation (TMS) to investigate hemodynamic responses to repetitive TMS (rTMS). Hemodynamic responses and visual evoked potentials (VEPs) to 3, 6, and 12 s stimuli consisting of pattern-reversing checkerboards were successfully recorded in the NIRS/EEG measurement, and ipsi- and contralateral hemodynamic responses to 0.5, 1, and 2 Hz rTMS in the NIRS/TMS measurement. In the NIRS/EEG measurements, the amplitudes of the hemodynamic responses increased from 3- to 6-s stimulus, but not from 6- to 12-s stimulus, and the VEPs showed peaks N75, P100, and N135. In the NIRS/TMS measurements, the 2-Hz stimulus produced the strongest hemodynamic responses compared to the 0.5- and 1-Hz stimuli. In two subjects oxyhemoglobin concentration decreased and in one increased as a consequence of the 2-Hz rTMS. To locate the origin of the measured NIRS responses, methods have to be developed to investigate TMS-induced scalp muscle contractions. In the future, multimodal measurements may prove useful in monitoring or treating diseases such as stroke or Alzheimer's disease.

Neurosteroid allopregnanolone reduces ipsilateral visual cortex potentiation following unilateral optic nerve injury.

PubMed

Sergeeva, Elena G; Espinosa-Garcia, Claudia; Atif, Fahim; Pardue, Machelle T; Stein, Donald G

2018-05-02

In adult mice with unilateral optic nerve crush injury (ONC), we studied visual response plasticity in the visual cortex following stimulation with sinusoidal grating. We examined visually evoked potentials (VEP) in the primary visual cortex ipsilateral and contralateral to the crushed nerve. We found that unilateral ONC induces enhancement of visual response on the side ipsilateral to the injury that is evoked by visual stimulation to the intact eye. This enhancement was associated with supranormal spatial frequency thresholds in the intact eye when tested using optomotor response. To probe whether injury-induced disinhibition caused the potentiation, we treated animals with the neurosteroid allopregnanolone, a potent agonist of the GABA A receptor, one hour after crush and on post-injury days 3, 8, 13, and 18. Allopregnanolone diminished enhancement of the VEP and this effect was associated with the upregulated synthesis of the δ-subunit of the GABA A receptor. Our study shows a new aspect of experience-dependent plasticity following unilateral ONC. This hyper-activity in the ipsilateral visual cortex is prevented by upregulation of GABA inhibition with allopregnanolone. Our findings suggest the therapeutic potential of allopregnanolone for modulation of plasticity in certain eye and brain disorders and a possible role for disinhibition in ipsilateral hyper-activity following unilateral ONC. Copyright © 2018. Published by Elsevier Inc.

Neurorehabilitation strategies for poststroke oropharyngeal dysphagia: from compensation to the recovery of swallowing function.

PubMed

Cabib, Christopher; Ortega, Omar; Kumru, Hatice; Palomeras, Ernest; Vilardell, Natalia; Alvarez-Berdugo, Daniel; Muriana, Desirée; Rofes, Laia; Terré, Rosa; Mearin, Fermín; Clavé, Pere

2016-09-01

Oropharyngeal dysphagia (OD) is very prevalent among poststroke patients, causing severe complications but lacking specific neurorehabilitation treatment. This review covers advances in the pathophysiology, diagnosis, and physiologically based neurorehabilitation strategies for poststroke OD. The pathophysiology of oropharyngeal biomechanics can be assessed by videofluoroscopy, as delayed laryngeal vestibule closure is closely associated with aspiration. Stroke may affect afferent or efferent neuronal circuits participating in deglutition. The integrity of oropharyngeal-cortical afferent pathways can be assessed by electroencephalography through sensory-evoked potentials by pharyngeal electrical stimulation, while corticopharyngeal efferent pathways can be characterized by electromyography through motor-evoked potentials by transcranial magnetic stimulation. Dysfunction in both cortico-mediated evoked responses is associated with delayed swallow response and aspiration. Studies have reported hemispherical asymmetry on motor control of swallowing and the relevance of impaired oropharyngeal sensitivity on aspiration. Advances in treatment include improvements in compensatory strategies but are mainly focused on (1) peripheral stimulation strategies and (2) central, noninvasive stimulation strategies with evidence of their clinical benefits. Characterization of poststroke OD is evolving from the assessment of impaired biomechanics to the sensorimotor integration processes involved in deglutition. Treatment is also changing from compensatory strategies to promoting brain plasticity, both to recover swallow function and to improve brain-related swallowing dysfunction. © 2016 New York Academy of Sciences.

Intraoperative Neurophysiological Monitoring in Spine Surgery: A Significant Tool for Neuronal Protection and Functional Restoration.

PubMed

Scibilia, Antonino; Raffa, Giovanni; Rizzo, Vincenzo; Quartarone, Angelo; Visocchi, Massimiliano; Germanò, Antonino; Tomasello, Francesco

2017-01-01

Although there is recent evidence for the role of intraoperative neurophysiological monitoring (IONM) in spine surgery, there are no uniform opinions on the optimal combination of the different tools. At our institution, multimodal IONM (mIONM) approach in spine surgery involves the evaluation of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) with electrical transcranial stimulation, including the use of a multipulse technique with multiple myomeric registration of responses from limbs, and a single-pulse technique with D-wave registration through epi- and intradural recording, and free running and evoked electromyography (frEMG and eEMG) with bilateral recording from segmental target muscles. We analyzed the impact of the mIONM on the preservation of neuronal structures and on functional restoration in a prospective series of patients who underwent spine surgery. We observed an improvement of neurological status in 50 % of the patients. The D-wave registration was the most useful intraoperative tool, especially when MEP and SEP responses were absent or poorly recordable. Our preliminary data confirm that mIONM plays a fundamental role in the identification and functional preservation of the spinal cord and nerve roots. It is highly sensitive and specific for detecting and avoiding neurological injury during spine surgery and represents a helpful tool for achieving optimal postoperative functional outcome.

An Assessment of the Potential Uses of Agonistic Behaviors in Termite Control

Treesearch

Barbara L. Thorne; Michael I. Haverty

1991-01-01

The potential use of termite-termite agonism in pest control is explored and evaluated. Intra-and interspecific en-counters among termites from different colonies are known to result in aggressive or avoidance behaviors in a variety of species. Recent studies suggest, however, that intraspecific confrontations only rarely evoke aggressive responses in several...

Atypical Brain Responses to Reward Cues in Autism as Revealed by Event-Related Potentials

ERIC Educational Resources Information Center

Kohls, Gregor; Peltzer, Judith; Schulte-Ruther, Martin; Kamp-Becker, Inge; Remschmidt, Helmut; Herpertz-Dahlmann, Beate; Konrad, Kerstin

2011-01-01

Social motivation deficit theories suggest that children with autism do not properly anticipate and appreciate the pleasure of social stimuli. In this study, we investigated event-related brain potentials evoked by cues that triggered social versus monetary reward anticipation in children with autism. Children with autism showed attenuated P3…

The early identification of anxiety-laden material with the aid of skin conductance measurements.

PubMed

Lukens, H R

1979-01-01

Measured electrodermal responses (EDR), in the form of changes in skin conductivity, during administration of a calibration questionnaire (CQ) and a personal history questionnaire (PHQ) to each of 25 Ss. "Strong" changes were defined statistically for each S from the amplitudes of EDR evoked by the CQ. The free-floating anxiety of each S also was measured. As predicted on the grounds that questions of the PHQ were more likely than the non-personal questions of the CQ to intersect unresolved, anxiety-laden material, it was found that strong EDR evoked by the PHQ were significantly more likely to perseverate than those evoked by the CQ. Hence, the technique has potential clinical use in identifying anxiety-laden material. Free-floating anxiety did not correlate significantly with EDR data.

Electrically-evoked frequency-following response (EFFR) in the auditory brainstem of guinea pigs.

PubMed

He, Wenxin; Ding, Xiuyong; Zhang, Ruxiang; Chen, Jing; Zhang, Daoxing; Wu, Xihong

2014-01-01

It is still a difficult clinical issue to decide whether a patient is a suitable candidate for a cochlear implant and to plan postoperative rehabilitation, especially for some special cases, such as auditory neuropathy. A partial solution to these problems is to preoperatively evaluate the functional integrity of the auditory neural pathways. For evaluating the strength of phase-locking of auditory neurons, which was not reflected in previous methods using electrically evoked auditory brainstem response (EABR), a new method for recording phase-locking related auditory responses to electrical stimulation, called the electrically evoked frequency-following response (EFFR), was developed and evaluated using guinea pigs. The main objective was to assess feasibility of the method by testing whether the recorded signals reflected auditory neural responses or artifacts. The results showed the following: 1) the recorded signals were evoked by neuron responses rather than by artifact; 2) responses evoked by periodic signals were significantly higher than those evoked by the white noise; 3) the latency of the responses fell in the expected range; 4) the responses decreased significantly after death of the guinea pigs; and 5) the responses decreased significantly when the animal was replaced by an electrical resistance. All of these results suggest the method was valid. Recording obtained using complex tones with a missing fundamental component and using pure tones with various frequencies were consistent with those obtained using acoustic stimulation in previous studies.

Effects of phloretin and phloridzin on Ca2+ handling, the action potential, and ion currents in rat ventricular myocytes.

PubMed

Olson, Marnie L; Kargacin, Margaret E; Ward, Christopher A; Kargacin, Gary J

2007-06-01

The effects of the phytoestrogens phloretin and phloridzin on Ca(2+) handling, cell shortening, the action potential, and Ca(2+) and K(+) currents in freshly isolated cardiac myocytes from rat ventricle were examined. Phloretin increased the amplitude and area and decreased the rate of decline of electrically evoked Ca(2+) transients in the myocytes. These effects were accompanied by an increase in the Ca(2+) load of the sarcoplasmic reticulum, as determined by the area of caffeine-evoked Ca(2+) transients. An increase in the extent of shortening of the myocytes in response to electrically evoked action potentials was also observed in the presence of phloretin. To further examine possible mechanisms contributing to the observed changes in Ca(2+) handling and contractility, the effects of phloretin on the cardiac action potential and plasma membrane Ca(2+) and K(+) currents were examined. Phloretin markedly increased the action potential duration in the myocytes, and it inhibited the Ca(2+)-independent transient outward K(+) current (I(to)). The inwardly rectifying K(+) current, the sustained outward delayed rectifier K(+) current, and L-type Ca(2+) currents were not significantly different in the presence and absence of phloretin, nor was there any evidence that the Na(+)/Ca(2+) exchanger was affected. The effects of phloretin on Ca(2+) handling in the myocytes are consistent with its effects on I(to). Phloridzin did not significantly alter the amplitude or area of electrically evoked Ca(2+) transients in the myocytes, nor did it have detectable effects on the sarcoplasmic reticulum Ca(2+) load, cell shortening, or the action potential.

Brainstem auditory and somatosensory evoked potentials in relation to clinical and neuroimaging findings in Chiari type 1 malformation.

PubMed

Moncho, Dulce; Poca, Maria-Antonia; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

2015-04-01

The aim of this study was to describe the abnormalities found in the recordings of evoked potentials (EPs), in particular those of brainstem auditory evoked potentials and somatosensory evoked potentials, in a homogeneous series of patients with Chiari type 1 malformation (CM-1) and study their relationship with clinical symptoms and malformation severity. CM-1 is characterized by cerebellar tonsils that descend below the foramen magnum and may be associated with EP alterations. However, only a small number of authors have described these tests in CM-1, and the patient groups studied to date have been small and heterogeneous. The clinical findings, neuroimages, and EP findings were retrospectively studied in a cohort of 50 patients with CM-1. Seventy percent of patients had EP abnormalities (brainstem auditory evoked potential: 52%, posterior tibial nerve somatosensory evoked potential: 42%, and median nerve somatosensory evoked potential: 34%). The most frequent alteration was an increased central conduction time. Morphometric measurements differed between the normal and pathological groups, although no statistical significance was found when comparing these groups. A high percentage of patients with CM-1 show EP alterations regardless of their clinical or radiological findings, thus highlighting the necessity of performing these tests, especially in patients with few or no symptoms.

Eugenol and carvacrol excite first- and second-order trigeminal neurons and enhance their heat-evoked responses

PubMed Central

Klein, Amanda H.; Joe, Christopher L.; Davoodi, Auva; Takechi, Kenichi; Carstens, Mirela Iodi; Carstens, E

2014-01-01

Eugenol and carvacrol from clove and oregano, respectively, are agonists of the warmth-sensitive transient receptor potential channel TRPV3 and the irritant-sensitive TRPA1. Eugenol and carvacrol induce oral irritation that rapidly desensitizes, accompanied by brief enhancement of innocuous warmth and heat pain in humans. We presently investigated if eugenol and carvacrol activate nociceptive primary afferent and higher-order trigeminal neurons and enhance their heat-evoked responses, using calcium imaging of cultured trigeminal ganglion (TG) and dorsal root ganglion (DRG) neurons, and in vivo single-unit recordings in trigeminal subnucleus caudalis (Vc) of rats. Eugenol and carvacrol activated 20-30% of TG and 7-20% of DRG cells, the majority of which additionally responded to menthol, mustard oil and/or capsaicin. TG cell responses to innocuous (39°) and noxious (42°C) heating were enhanced by eugenol and carvacrol. We identified dorsomedial Vc neurons responsive to noxious heating of the tongue in pentobarbital-anesthetized rats. Eugenol and carvacrol dose-dependently elicited desensitizing responses in 55% and 73% of heat-sensitive units, respectively. Responses to noxious heat were briefly enhanced by eugenol and carvacrol. Many eugenol- and carvacrol-responsive units also responded to menthol, cinnamaldehyde and capsaicin. These data support a peripheral site for eugenol and carvacrol to enhance warmth- and noxious heat-evoked responses of trigeminal neurons, and are consistent with the observation that these agonists briefly enhance warmth and heat pain on the human tongue. PMID:24759772

Neurovascular and neuroimaging effects of the hallucinogenic serotonin receptor agonist psilocin in the rat brain

PubMed Central

Spain, Aisling; Howarth, Clare; Khrapitchev, Alexandre A.; Sharp, Trevor; Sibson, Nicola R.; Martin, Chris

2015-01-01

The development of pharmacological magnetic resonance imaging (phMRI) has presented the opportunity for investigation of the neurophysiological effects of drugs in vivo. Psilocin, a hallucinogen metabolised from psilocybin, was recently reported to evoke brain region-specific, phMRI signal changes in humans. The present study investigated the effects of psilocin in a rat model using phMRI and then probed the relationship between neuronal and haemodynamic responses using a multimodal measurement preparation. Psilocin (2 mg/kg or 0.03 mg/kg i.v.) or vehicle was administered to rats (N = 6/group) during either phMRI scanning or concurrent imaging of cortical blood flow and recording of local field potentials. Compared to vehicle controls psilocin (2 mg/kg) evoked phMRI signal increases in a number of regions including olfactory and limbic areas and elements of the visual system. PhMRI signal decreases were seen in other regions including somatosensory and motor cortices. Investigation of neurovascular coupling revealed that whilst neuronal responses (local field potentials) to sensory stimuli were decreased in amplitude by psilocin administration, concurrently measured haemodynamic responses (cerebral blood flow) were enhanced. The present findings show that psilocin evoked region-specific changes in phMRI signals in the rat, confirming recent human data. However, the results also suggest that the haemodynamic signal changes underlying phMRI responses reflect changes in both neuronal activity and neurovascular coupling. This highlights the importance of understanding the neurovascular effects of pharmacological manipulations for interpreting haemodynamic neuroimaging data. PMID:26192543

Vestibular Response to Electrical Stimulation of the Otolith Organs. Implications in the Development of A Vestibular Implant for the Improvement of the Sensation of Gravitoinertial Accelerations.

PubMed

Ramos de Miguel, Angel; Falcon Gonzalez, Juan Carlos; Ramos Macias, Angel

2017-08-01

Electrical stimulation of the utricular and saccular portions of the vestibular nerve improves stability in patients suffering from vestibular dysfunction. The main objective of this study was to evaluate a new technique, vestibular response telemetry (VRT), for measuring the electrically evoked vestibular compound action potential (saccular and utricular) after stimulating the otolith organ (saccular and utricular) in adults. This study used evidence that the otolith organ can be electrically stimulated in order to develop a new vestibular implant design to improve the sensation of gravitoinertial acceleration. Four adult patients were evaluated by using a variety of measurement procedures with novel VRT software. VRT values were obtained by stimulating with three full-band Nucleus CI24RE (ST) electrodes. Specific stimuli were used. Simultaneously, electrical ocular vestibular evoked myogenic potentials (eoVEMPs) were recorded in the contralateral side. Electrically evoked compound action potentials were obtained in 10 of the 12 electrodes tested, and eoVEMPs were recorded when VRT was present. In addition to the validation of this technique, a set of default clinical test parameters was established. The VRT response morphology consisted of a biphasic waveform with an initial negative peak (N1) followed by a positive peak (P1), and latencies were typically 400 μs for N1 and 800 μs for P1. The consequences for the development of a vestibular implant for the improvement of gravitoinertial acceleration sensation are also presented. The VRT measurement technique has been shown to be a useful tool to record neural response on the otolith organ, and thus it is a convenient tool to evaluate whether the implanted electrodes provide a neural response or not. This can be used for the early development of vestibular implants to improve gravitoinertial acceleration sensation.

Sex Differences in the Association between Stressor-Evoked Interleukin-6 Reactivity and C-Reactive Protein

PubMed Central

Lockwood, Kimberly G.; Marsland, Anna L.; Cohen, Sheldon; Gianaros, Peter J.

2016-01-01

Individuals differ consistently in the magnitude of their inflammatory responses to acute stressors, with females often showing larger responses than males. While the clinical significance of these individual differences remains unclear, it may be that greater inflammatory responses relate to increased systemic inflammation and thereby risk for chronic inflammatory disease. Here, we examined whether acute stressor-evoked interleukin (IL)-6 responses associate with resting levels of C-reactive protein (CRP), a marker of systemic inflammation, and whether this association differs by sex. Subjects were 57 healthy midlife adults (30–51 years; 33% female; 68% white). Blood was drawn before and 30-min after two mental stress tasks: a multisource interference task and a Stroop color word task. Hierarchical regressions controlling for age, sex, race, and BMI tested whether stressor-evoked IL-6 responses were associated with resting CRP and whether this association differed by sex. Results indicated that sex and stressor-evoked IL-6 responses interacted to predict CRP (ΔR2 = .08, B = −1.33, β = −.39, p = .02). In males, larger stressor-evoked IL-6 responses associated with higher CRP, whereas in females, stressor-evoked IL-6 responses showed a non-significant negative association with CRP. These findings indicate that inflammatory responses to acute stressors associate with resting levels of CRP; however, this association differs by sex. Previous literature suggests that there are sex differences in stressor-evoked IL-6 responses, but this is the first study to show sex differences in the relationship between acute inflammatory responses and systemic inflammation. The contribution of these sex differences to inflammatory disease risk warrants further investigation. PMID:27377561

Responses to GABA(A) receptor activation are altered in NTS neurons isolated from renal-wrap hypertensive rats.

PubMed

Tolstykh, Gleb; Belugin, Sergei; Tolstykh, Olga; Mifflin, Steve

2003-10-01

The inhibitory amino acid GABA is a potent modulator of the spontaneous discharge and the responses to afferent inputs of neurons in the nucleus of the solitary tract (NTS). To determine if responses to activation of GABA(A) receptors are altered in hypertension, GABA(A) receptor-evoked whole cell currents were measured in enzymatically dispersed NTS neurons from 33 normotensive (NT, 109+/-4 mm Hg, n=7) and 24 hypertensive (HT, 167+/-5 mm Hg, n=24) rats. GABA(A) receptor-evoked currents reversed at the calculated equilibrium potential for chloride and were blocked by bicuculline (n=6). Membrane capacitance was the same in neurons from NT (7.5+/-0.6 pF, n=62) and HT (6.8+/-0.6 pF, n=51) rats. The EC50 for peak GABA-evoked currents cells was significantly greater in neurons from HT (21.0+/-2.6 micromol/L, n=16) compared with NT rats (13.0+/-1.8 micromol/L, n=14, P=0.01). The EC50 of neurons exhibiting DiA labeling of presumptive aortic nerve terminals was no different than that observed in the nonlabeled cells (19.0+/-4.9 micromol/L, n=4). The time constant for desensitization of GABA(A)-evoked currents was the same in neurons from HT (4.5+/-0.3 seconds, n=17) and NT rats (3.8+/-0.3 seconds, n=17, P>0.05). Repetitive pulse application of GABA revealed a more rapid decline in the evoked current in neurons from HT compared with NT rats. The amplitude of the 5th pulse of GABA (5-second duration, 2-second interval) was 21+/-2% the amplitude of the 1st pulse in NT rats (n=10) and 14+/-2% in HT rats (n=11, P<0.05). These alterations in GABAA-receptor evoked currents could render the neurons less sensitive to GABA(A) receptor inhibition and influence afferent integration by NTS neurons in HT.

Glomerular Activity Patterns Evoked by Natural Odor Objects in the Rat Olfactory Bulb Are Related to Patterns Evoked by Major Odorant Components

PubMed Central

Johnson, Brett A.; Ong, Joan; Leon, Michael

2014-01-01

To determine how responses evoked by natural odorant mixtures compare to responses evoked by individual odorant chemicals, we mapped 2-deoxyglucose uptake during exposures to vapors arising from a variety of odor objects that may be important to rodents in the wild. We studied 21 distinct natural odor stimuli ranging from possible food sources such as fruits, vegetables, and meats to environmental odor objects such as grass, herbs, and tree leaves. The natural odor objects evoked robust and surprisingly focal patterns of 2-deoxyglucose uptake involving clusters of neighboring glomeruli, thereby resembling patterns evoked by pure chemicals. Overall, the patterns were significantly related to patterns evoked by monomolecular odorant components that had been studied previously. Object patterns also were significantly related to the molecular features present in the mixture components. Despite these overall relationships, there were individual examples of object patterns that were simpler than might have been predicted given the multiplicity of components present in the vapors. In these cases, the object patterns lacked certain responses evoked by their major odorant mixture components. These data suggest the possibility of mixture response interactions and provide a foundation for understanding the neural coding of natural odor stimuli. PMID:20187145

Paradoxical monocular stereopsis and perspective vergence

NASA Technical Reports Server (NTRS)

Enright, J. T.

1989-01-01

The question of how to most effectively convey depth in a picture is a multifaceted problem, both because of potential limitations of the chosen medium (stereopsis, image motion), and because effectiveness can be defined in various ways. Practical applications usually focus on information transfer, i.e., effective techniques for evoking recognition of implied depth relationships, but this issue depends on subjective judgements which are difficult to scale when stimuli are above threshold. Two new approaches to this question are proposed here which are based on alternative criteria for effectiveness. Paradoxical monocular stereopsis is a remarkably compelling impression of depth which is evoked during one-eyed viewing of only certain illustrations; it can be unequivocally recognized because the feeling of depth collapses when one shifts to binocular viewing. An exploration of the stimulus properties which are effective for this phenomenon may contribute useful answers for the more general perceptual problem. Positive vergence is an eye-movement response associated with changes of fixation point within a picture which implies depth; it also arises only during monocular viewing. The response is directionally appropriate (i.e., apparently nearer objects evoke convergence, and vice versa), but the magnitude of the response can be altered consistently by making relatively minor changes in the illustration. The cross-subject agreement in changes of response magnitude would permit systematic exploration to determine which stimulus configurations are most effective in evoking perspective vergence, with quantitative answers based upon this involuntary reflex. It may well be that most effective pictures in this context will embody features which would increase effectiveness of pictures in a more general sense.

4-aminopyridine in scala media reversibly alters the cochlear potentials and suppresses electrically evoked oto-acoustic emissions.

PubMed

Kirk, D L; Yates, G K

1998-01-01

Iontophoresis of 4-aminopyridine into scala media of the guinea pig cochlea caused elevation of the thresholds of the compound action potential of the auditory nerve, loss of amplitude of the extracellular cochlear microphonic response (CM), increase in the endocochlear potential (EP) and reduction in the amplitude of electrically evoked oto-acoustic emissions (EEOAEs). These changes were reversible over 10-20 min. The reciprocity of the changes in the CM and the EP was consistent with an interruption of both DC and AC currents through outer hair cells (OHCs), probably by blockade of mechano-electrical transduction (MET) channels in OHCs. Reductions in EEOAEs were consistent with the extrinsically applied generating current entering the OHC via the MET channels. Implications for the activation of OHC electromotility in vivo are discussed.

Arctigenin reduces neuronal responses in the somatosensory cortex via the inhibition of non-NMDA glutamate receptors.

PubMed

Borbély, Sándor; Jócsák, Gergely; Moldován, Kinga; Sedlák, Éva; Preininger, Éva; Boldizsár, Imre; Tóth, Attila; Atlason, Palmi T; Molnár, Elek; Világi, Ildikó

2016-07-01

Lignans are biologically active phenolic compounds related to lignin, produced in different plants. Arctigenin, a dibenzylbutyrolactone-type lignan, has been used as a neuroprotective agent for the treatment of encephalitis. Previous studies of cultured rat cerebral cortical neurones raised the possibility that arctigenin inhibits kainate-induced excitotoxicity. The aims of the present study were: 1) to analyse the effect of arctigenin on normal synaptic activity in ex vivo brain slices, 2) to determine its receptor binding properties and test the effect of arctigenin on AMPA/kainate receptor activation and 3) to establish its effects on neuronal activity in vivo. Arctigenin inhibited glutamatergic transmission and reduced the evoked field responses. The inhibitory effect of arctigenin on the evoked field responses proved to be substantially dose dependent. Our results indicate that arctigenin exerts its effects under physiological conditions and not only on hyper-excited neurons. Furthermore, arctigenin can cross the blood-brain barrier and in the brain it interacts with kainate sensitive ionotropic glutamate receptors. These results indicate that arctigenin is a potentially useful new pharmacological tool for the inhibition of glutamate-evoked responses in the central nervous system in vivo. Copyright © 2016 Elsevier Ltd. All rights reserved.

Involvement of metabotropic glutamate 5 receptor in visceral pain.

PubMed

Lindström, Erik; Brusberg, Mikael; Hughes, Patrick A; Martin, Christopher M; Brierley, Stuart M; Phillis, Benjamin D; Martinsson, Rakel; Abrahamsson, Christina; Larsson, Håkan; Martinez, Vicente; Blackshaw, L Ashley

2008-07-15

Metabotropic glutamate 5 receptor (mGluR5) antagonists are effective in animal models of inflammatory and neuropathic pain. The involvement of mGluR5 in visceral pain pathways from the gastrointestinal tract is as yet unknown. We evaluated effects of mGluR5 antagonists on the colorectal distension (CRD)-evoked visceromotor (VMR) and cardiovascular responses in conscious rats, and on mechanosensory responses of mouse colorectal afferents in vitro. Sprague-Dawley rats were subjected to repeated, isobaric CRD (12 x 80 mmHg, for 30s with 5 min intervals). The VMR and cardiovascular responses to CRD were monitored. The mGluR5 antagonists MPEP (1-10 micromol/kg, i.v.) and MTEP (1-3 micromol/kg, i.v.) reduced the VMR to CRD dose-dependently with maximal inhibition of 52+/-8% (p<0.01) and 25+/-11% (p<0.05), respectively, without affecting colonic compliance. MPEP (10 micromol/kg, i.v.) reduced CRD-evoked increases in blood pressure and heart rate by 33+/-9% (p<0.01) and 35+/-8% (p<0.05), respectively. Single afferent recordings were made from mouse pelvic and splanchnic nerves of colorectal mechanoreceptors. Circumferential stretch (0-5 g force) elicited slowly-adapting excitation of action potentials in pelvic distension-sensitive afferents. This response was reduced 55-78% by 10 microM MTEP (p<0.05). Colonic probing (2g von Frey hair) activated serosal splanchnic afferents; their responses were reduced 50% by 10 microM MTEP (p<0.01). We conclude that mGluR5 antagonists inhibit CRD-evoked VMR and cardiovascular changes in conscious rats, through an effect, at least in part, at peripheral afferent endings. Thus, mGluR5 participates in mediating mechanically evoked visceral nociception in the gastrointestinal tract.

The role of dorsomedial hypotalamus ionotropic glutamate receptors in the hypertensive and tachycardic responses evoked by Tityustoxin intracerebroventricular injection.

PubMed

Silva, F C; Guidine, Patrícia Alves Maia; Machado, Natalia Lima; Xavier, Carlos Henrique; de Menezes, R C; Moraes-Santos, Tasso; Moraes, Márcio Flávio; Chianca, Deoclécio Alves

2015-03-01

The scorpion envenoming syndrome is an important worldwide public health problem due to its high incidence and potential severity of symptoms. Some studies address the high sensitivity of the central nervous system to this toxin action. It is known that cardiorespiratory manifestations involve the activation of the autonomic nervous system. However, the origin of this modulation remains unclear. Considering the important participation of the dorsomedial hypotalamus (DMH) in the cardiovascular responses during emergencial situations, the aim of this work is to investigate the involvement of the DMH on cardiovascular responses induced by intracerebroventricular (icv) injection of Tityustoxin (TsTX, a α-type toxin extracted from the Tityus serrulatus scorpion venom). Urethane-anaesthetized male Wistar rats (n=30) were treated with PBS, muscimol or ionotropic glutamate receptor antagonists, bilaterally in DMH and later, with an icv injection of TsTX, or treated only with PBS in both regions. TsTX evoked a marked increase in mean arterial pressure and heart rate in all control rats. Interestingly, injection of muscimol, a GABAA receptor agonist, did not change the pressor and tachycardic responses evoked by TsTX. Remarkably, the injection ionotropic glutamate receptors antagonists in DMH abolished the pressor and the tachycardic response evoked by TsTX. Our data suggest that the central circuit recruited by TsTX, whose activation results in an array of physiological and behavioral alterations, depend on the activation of DMH ionotropic glutamate receptors. Moreover, our data provide new insights on the central mechanisms involved in the development of symptoms in the severe scorpion envenomation syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.

Pharmacology of Bradykinin-Evoked Coughing in Guinea Pigs.

PubMed

Hewitt, Matthew M; Adams, Gregory; Mazzone, Stuart B; Mori, Nanako; Yu, Li; Canning, Brendan J

2016-06-01

Bradykinin has been implicated as a mediator of the acute pathophysiological and inflammatory consequences of respiratory tract infections and in exacerbations of chronic diseases such as asthma. Bradykinin may also be a trigger for the coughing associated with these and other conditions. We have thus set out to evaluate the pharmacology of bradykinin-evoked coughing in guinea pigs. When inhaled, bradykinin induced paroxysmal coughing that was abolished by the bradykinin B2 receptor antagonist HOE 140. These cough responses rapidly desensitized, consistent with reports of B2 receptor desensitization. Bradykinin-evoked cough was potentiated by inhibition of both neutral endopeptidase and angiotensin-converting enzyme (with thiorphan and captopril, respectively), but was largely unaffected by muscarinic or thromboxane receptor blockade (atropine and ICI 192605), cyclooxygenase, or nitric oxide synthase inhibition (meclofenamic acid and N(G)-nitro-L-arginine). Calcium influx studies in bronchopulmonary vagal afferent neurons dissociated from vagal sensory ganglia indicated that the tachykinin-containing C-fibers arising from the jugular ganglia mediate bradykinin-evoked coughing. Also implicating the jugular C-fibers was the observation that simultaneous blockade of neurokinin2 (NK2; SR48968) and NK3 (SR142801 or SB223412) receptors nearly abolished the bradykinin-evoked cough responses. The data suggest that bradykinin induces coughing in guinea pigs by activating B2 receptors on bronchopulmonary C-fibers. We speculate that therapeutics targeting the actions of bradykinin may prove useful in the treatment of cough. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Gender differences in emotional responses: a psychophysiological study.

PubMed

Bianchin, Marta; Angrilli, Alessandro

2012-02-28

Gender differences in emotional responses have been investigated in two groups of students, 22 males and 21 females. Participants watched a set of sixty emotional standardized slides divided into pleasant, neutral and unpleasant, while Startle reflex, Evoked Potentials, Heart Rate, facial EMG and Skin Conductance were recorded. Startle reflex amplitude, an index modulated by amygdala and orbitofrontal cortex and sensitive to aversive emotional stimuli, was overall larger in women. In addition, startle emotion modulation was greater in women with respect to men. Slow Evoked Potentials (400-800 ms), a measure representing the cognitive component of the emotional response, revealed gender differences in the left prefrontal site, with women showing greater positivity to unpleasant compared with pleasant slides while men had greater positivity to pleasant vs. neutral slides. Women, compared with men, perceived all slides as less pleasant and reported greater arousal to unpleasant condition. Results are in line with known functional brain differences, at level of limbic and paralimbic structures, between men and women, and point to biologically grounded greater sensitivity and vulnerability of women to adverse/stressful events. Copyright © 2011 Elsevier Inc. All rights reserved.

Evoked-potential recovery during double click stimulation in a beluga whale: implications for biosonar gain control.

PubMed

Supin, Alexander Ya; Popov, Vladimir V

2015-05-01

Auditory evoked potentials (AEPs) were recorded in a beluga whale Delphinapterus leucas using a double-pulse stimulation paradigm, specifically measuring the recovery (release from masking) of the second (test) response as a function of delay after the first (conditioning) pulse at various levels of the conditioning and test stimuli. The conditioning/test stimulus level ratio influenced the recovery time (the higher the ratio, the longer the recovery). This interrelation was used to evaluate the intensity/time trade in release from forward masking. Trade was evaluated as 32.2 dB per time decade. Data were considered as simulating interactions between the transmitted pulse and echo during echolocation, assuming that a transmitted sonar pulse produces forward masking of the echo response. With increased target distance, the attenuation of the echo may be compensated by the release from masking. According to the model, the compensation results in substantial stabilization of the echo response even if the intensity/time trade of release from masking is not precisely equal to the rate of echo attenuation with distance.

Changes in the somatosensory evoked potentials and spontaneous electroencephalogram of hens during stunning in argon-induced anoxia.

PubMed

Raj, A B; Gregory, N G; Wotton, S B

1991-01-01

This study examined the time to loss of consciousness in hens during stunning in argon-induced anoxia. Somatosensory evoked potentials (SEPs) and the spontaneous electroencephalogram (EEG) were recorded in 12 culled hens prior to and during stunning in less than 2% oxygen (air displaced by argon). An additional 20 hens were stunned with a similar concentration of oxygen and the time to loss of posture, eye closure, and the onset and duration of clonic and tonic convulsions were recorded. A further 10 hens were immersed in less than 2% oxygen for 15-17 s and their response to comb pinching was tested as soon as they had been transferred to atmospheric air. It is concluded that the birds had not lost the primary response in their SEPs by the time they started convulsing, but the reduction in the amplitude of the SEPs, changes in their spontaneous EEG and a negative response to comb pinch before the start of the convulsions indicated that the birds were unconscious when they convulsed.

Auditory evoked potentials: predicting speech therapy outcomes in children with phonological disorders.

PubMed

Leite, Renata Aparecida; Wertzner, Haydée Fiszbein; Gonçalves, Isabela Crivellaro; Magliaro, Fernanda Cristina Leite; Matas, Carla Gentile

2014-03-01

This study investigated whether neurophysiologic responses (auditory evoked potentials) differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy. The participants included 24 typically developing children (Control Group, mean age: eight years and ten months) and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months). Additionally, 12 study group children were enrolled in speech therapy (Study Group 1), and 11 were not enrolled in speech therapy (Study Group 2). The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups. Latency differences were observed between the groups (the control and study groups) regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy. The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy.

Vestibular evoked myogenic potential according to middle ear condition in chronic otitis media with tympanic membrane perforation.

PubMed

Lee, Jun Seok; Lee, Sun Kyu; Shin, Il Ho; Yeo, Seung Geun; Park, Moon Suh; Byun, Jae Yong

2014-01-01

Vestibular evoked myogenic potential (VEMP) function results can vary between individuals with different middle ear conditions. Therefore, by analyzing VEMP results after paper patching, we can predict the condition of the middle ear in chronic otitis media (COM) patients. VEMP responses decrease with impairment of sound transmission, such as in conductive hearing loss (CHL). COM with tympanic membrane (TM) perforation is a common disorder that causes various degrees of CHL. The aim of this study was to evaluate and clarify the VEMP responses in patients with COM with different middle ear pathology. This study included 50 patients with unilateral COM with TM perforation. Initial pure-tone audiometry (PTA) and VEMP responses were recorded. After paper patching, PTA and VEMP were re-performed. Each VEMP response was compared with those of the healthy controls. Moreover, VEMP responses between pre- and post-paper patching were compared. There was a positive correlation between normalizing of VEMP parameters, such as p13 and VEMP asymmetry ratio (VAR), and reduction of air-bone gap in patients with COM after paper patching. The VEMP response in patients with COM with intact ossicle and clean mucosa was more normalized compared with those in patients with COM with different middle ear conditions.

The Relationship between the Behavioral Hearing Thresholds and Maximum Bilirubin Levels at Birth in Children with a History of Neonatal Hyperbilirubinemia

PubMed Central

Panahi, Rasool; Jafari, Zahra; Sheibanizade, Abdoreza; Salehi, Masoud; Esteghamati, Abdoreza; Hasani, Sara

2013-01-01

Introduction: Neonatal hyperbilirubinemia is one of the most important factors affecting the auditory system and can cause sensorineural hearing loss. This study investigated the relationship between behavioral hearing thresholds in children with a history of jaundice and the maximum level of bilirubin concentration in the blood. Materials and Methods: This study was performed on 18 children with a mean age of 5.6 years and with a history of neonatal hyperbilirubinemia. Behavioral hearing thresholds, transient evoked emissions and brainstem evoked responses were evaluated in all children. Results: Six children (33.3%) had normal hearing thresholds and the remaining (66.7%) had some degree of hearing loss. There was no significant relationship (r=-0.28, P=0.09) between the mean total bilirubin levels and behavioral hearing thresholds in all samples. A transient evoked emission was seen only in children with normal hearing thresholds however in eight cases brainstem evoked responses had not detected. Conclusion: Increased blood levels of bilirubin at the neonatal period were potentially one of the causes of hearing loss. There was a lack of a direct relationship between neonatal bilirubin levels and the average hearing thresholds which emphasizes on the necessity of monitoring the various amounts of bilirubin levels. PMID:24303432

Effect of ethanol on the visual-evoked potential in rat: dynamics of ON and OFF responses.

PubMed

Dulinskas, Redas; Buisas, Rokas; Vengeliene, Valentina; Ruksenas, Osvaldas

2017-01-01

The effect of acute ethanol administration on the flash visual-evoked potential (VEP) was investigated in numerous studies. However, it is still unclear which brain structures are responsible for the differences observed in stimulus onset (ON) and offset (OFF) responses and how these responses are modulated by ethanol. The aim of our study was to investigate the pattern of ON and OFF responses in the visual system, measured as amplitude and latency of each VEP component following acute administration of ethanol. VEPs were recorded at the onset and offset of a 500 ms visual stimulus in anesthetized male Wistar rats. The effect of alcohol on VEP latency and amplitude was measured for one hour after injection of 2 g/kg ethanol dose. Three VEP components - N63, P89 and N143 - were analyzed. Our results showed that, except for component N143, ethanol increased the latency of both ON and OFF responses in a similar manner. The latency of N143 during OFF response was not affected by ethanol but its amplitude was reduced. Our study demonstrated that the activation of the visual system during the ON response to a 500 ms visual stimulus is qualitatively different from that during the OFF response. Ethanol interfered with processing of the stimulus duration at the level of the visual cortex and reduced the activation of cortical regions.

Assessment and Development of Oculomotor Flying Skills by the Application of the Channel Theory of Vision.

DTIC Science & Technology

1983-11-04

visual acuity in amblyopia , using steady-state visual evoked potentials. In J. E. Desmedt (Ed.), Visual evoked potentials in man: new developments... amblyopia by the evoked potential method. Ophthalmologica, 1977s 175, 159-164. 61. Regan, D. & Spekreijse, H. Auditory-visual interactions and the

Postoperative neurological deficits may occur despite unchanged intraoperative somatosensory evoked potentials.

PubMed

Lesser, R P; Raudzens, P; Lüders, H; Nuwer, M R; Goldie, W D; Morris, H H; Dinner, D S; Klem, G; Hahn, J F; Shetter, A G

1986-01-01

We describe 6 patients who demonstrated postoperative neurological deficits despite unchanged somatosensory evoked potentials during intraoperative monitoring. Although there is both experimental and clinical evidence that somatosensory evoked potentials are sensitive to some types of intraoperative mishap, the technique should be employed with an awareness of its possible limitations.

Neurotoxic effects of n-hexane on the human central nervous system: evoked potential abnormalities in n-hexane polyneuropathy.

PubMed Central

Chang, Y C

1987-01-01

An outbreak of n-hexane polyneuropathy as a result of industrial exposure occurred in printing factories in Taipei area from December 1983 to February 1985. Multimodality evoked potentials study was performed on 22 of the polyneuropathy cases, five of the subclinical cases, and seven of the unaffected workers. The absolute and interpeak latencies of patterned visual evoked potential (pVEP) in both the polyneuropathy and subclinical groups were longer than in the normal controls. The pVEP interpeak amplitude was also decreased in the polyneuropathy cases. Brainstem auditory evoked potentials (BAEP), showed no difference of wave I latency between factory workers and normal controls, but prolongation of the wave I-V interpeak latencies was noted, corresponding with the severity of the polyneuropathy. In somatosensory evoked potentials (SEPs), both the absolute latencies and central conduction time (CCT) were longer in subclinical and polyneuropathy cases than in the unaffected workers and normal controls. From this evoked potentials study, chronic toxic effects of n-hexane on the central nervous system were shown. PMID:3031221

N1 Magnitude of Auditory Evoked Potentials and Spontaneous Functional Connectivity Between Bilateral Heschl's Gyrus Are Coupled at Interindividual Level.

PubMed

Tan, Ao; Hu, Li; Tu, Yiheng; Chen, Rui; Hung, Yeung Sam; Zhang, Zhiguo

2016-07-01

N1 component of auditory evoked potentials is extensively used to investigate the propagation and processing of auditory inputs. However, the substantial interindividual variability of N1 could be a possible confounding factor when comparing different individuals or groups. Therefore, identifying the neuronal mechanism and origin of the interindividual variability of N1 is crucial in basic research and clinical applications. This study is aimed to use simultaneously recorded electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data to investigate the coupling between N1 and spontaneous functional connectivity (FC). EEG and fMRI data were simultaneously collected from a group of healthy individuals during a pure-tone listening task. Spontaneous FC was estimated from spontaneous blood oxygenation level-dependent (BOLD) signals that were isolated by regressing out task evoked BOLD signals from raw BOLD signals and then was correlated to N1 magnitude across individuals. It was observed that spontaneous FC between bilateral Heschl's gyrus was significantly and positively correlated with N1 magnitude across individuals (Spearman's R = 0.829, p < 0.001). The specificity of this observation was further confirmed by two whole-brain voxelwise analyses (voxel-mirrored homotopic connectivity analysis and seed-based connectivity analysis). These results enriched our understanding of the functional significance of the coupling between event-related brain responses and spontaneous brain connectivity, and hold the potential to increase the applicability of brain responses as a probe to the mechanism underlying pathophysiological conditions.

Low-frequency stimulation cancels the high-frequency-induced long-lasting effects in the rat medial vestibular nuclei.

PubMed

Grassi, S; Pettorossi, V E; Zampolini, M

1996-05-15

In rat brainstem slices, we investigated the effects of low-frequency stimulation (LFS) of the primary vestibular afferents on the amplitude of the field potentials evoked in the medial vestibular nuclei (MVN). LFS induced long-term effects, the sign of which depended on whether the vestibular neurons were previously conditioned by HFS. In unconditioned slices, LFS evoked modifications of the responses that were similar to those observed after HFS but had a smaller extension. In fact, LFS caused long-lasting potentiation of the N1 wave in the MVN ventral portion (Vp) and long-lasting depression of the N2 wave in the MVN dorsal portion (Dp), whereas it provoked small and variable effects on the N1 wave. By contrast, when the synaptic transmission was already conditioned, LFS influenced the synaptic responses oppositely, reducing or annulling the HFS long-term effects. This phenomenon was specifically induced by LFS, because HFS was not able to cause it. The involvement of NMDA receptors in mediating the LFS long-term effects was supported by the fact that AP-5 prevented their induction. In addition, the annulment of HFS long-term effects by LFS was also demonstrated by the shift in the latency of the evoked unitary potentials after LFS. In conclusion, we suggest that the reduction of the previously induced conditioning could represent a cancellation mechanism, useful to quickly adapt the vestibular system to continuous different needs and to avoid saturation.

Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex.

PubMed

Kajikawa, Yoshinao; Smiley, John F; Schroeder, Charles E

2017-10-18

Prior studies have reported "local" field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be "contaminated" by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such "far-field" activity, in addition to, or in absence of, local synaptic responses. SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is problematic as the default assumption is that FPs originate from local activity, and thus are termed "local" (LFP). We examine this general problem in the context of previously reported face-evoked FPs in macaque auditory cortex. Our findings suggest that face-FPs are indeed generated in the underlying inferotemporal cortex and volume-conducted to the auditory cortex. The note of caution raised by these findings is of particular importance for studies that seek to assign FP/LFP recordings to specific cortical layers. Copyright © 2017 the authors 0270-6474/17/3710139-15$15.00/0.

Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex

PubMed Central

Smiley, John F.; Schroeder, Charles E.

2017-01-01

Prior studies have reported “local” field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be “contaminated” by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such “far-field” activity, in addition to, or in absence of, local synaptic responses. SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is problematic as the default assumption is that FPs originate from local activity, and thus are termed “local” (LFP). We examine this general problem in the context of previously reported face-evoked FPs in macaque auditory cortex. Our findings suggest that face-FPs are indeed generated in the underlying inferotemporal cortex and volume-conducted to the auditory cortex. The note of caution raised by these findings is of particular importance for studies that seek to assign FP/LFP recordings to specific cortical layers. PMID:28924008

LIMO EEG: a toolbox for hierarchical LInear MOdeling of ElectroEncephaloGraphic data.

PubMed

Pernet, Cyril R; Chauveau, Nicolas; Gaspar, Carl; Rousselet, Guillaume A

2011-01-01

Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB) and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses.

LIMO EEG: A Toolbox for Hierarchical LInear MOdeling of ElectroEncephaloGraphic Data

PubMed Central

Pernet, Cyril R.; Chauveau, Nicolas; Gaspar, Carl; Rousselet, Guillaume A.

2011-01-01

Magnetic- and electric-evoked brain responses have traditionally been analyzed by comparing the peaks or mean amplitudes of signals from selected channels and averaged across trials. More recently, tools have been developed to investigate single trial response variability (e.g., EEGLAB) and to test differences between averaged evoked responses over the entire scalp and time dimensions (e.g., SPM, Fieldtrip). LIMO EEG is a Matlab toolbox (EEGLAB compatible) to analyse evoked responses over all space and time dimensions, while accounting for single trial variability using a simple hierarchical linear modelling of the data. In addition, LIMO EEG provides robust parametric tests, therefore providing a new and complementary tool in the analysis of neural evoked responses. PMID:21403915

Delta and gamma oscillations in operculo-insular cortex underlie innocuous cold thermosensation

PubMed Central

Vinding, Mikkel C.; Allen, Micah; Jensen, Troels Staehelin; Finnerup, Nanna Brix

2017-01-01

Cold-sensitive and nociceptive neural pathways interact to shape the quality and intensity of thermal and pain perception. Yet the central processing of cold thermosensation in the human brain has not been extensively studied. Here, we used magnetoencephalography and EEG in healthy volunteers to investigate the time course (evoked fields and potentials) and oscillatory activity associated with the perception of cold temperature changes. Nonnoxious cold stimuli consisting of Δ3°C and Δ5°C decrements from an adapting temperature of 35°C were delivered on the dorsum of the left hand via a contact thermode. Cold-evoked fields peaked at around 240 and 500 ms, at peak latencies similar to the N1 and P2 cold-evoked potentials. Importantly, cold-related changes in oscillatory power indicated that innocuous thermosensation is mediated by oscillatory activity in the range of delta (1–4 Hz) and gamma (55–90 Hz) rhythms, originating in operculo-insular cortical regions. We suggest that delta rhythms coordinate functional integration between operculo-insular and frontoparietal regions, while gamma rhythms reflect local sensory processing in operculo-insular areas. NEW & NOTEWORTHY Using magnetoencephalography, we identified spatiotemporal features of central cold processing, with respect to the time course, oscillatory profile, and neural generators of cold-evoked responses in healthy human volunteers. Cold thermosensation was associated with low- and high-frequency oscillatory rhythms, both originating in operculo-insular regions. These results support further investigations of central cold processing using magnetoencephalography or EEG and the clinical utility of cold-evoked potentials for neurophysiological assessment of cold-related small-fiber function and damage. PMID:28250150

Brainstem Auditory Evoked Potential in HIV-Positive Adults.

PubMed

Matas, Carla Gentile; Samelli, Alessandra Giannella; Angrisani, Rosanna Giaffredo; Magliaro, Fernanda Cristina Leite; Segurado, Aluísio C

2015-10-20

To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment - research groups I and II, respectively - and 30 control group individuals) were assessed through brainstem auditory evoked potential. There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment.

Clinical significance of vestibular evoked myogenic potentials in benign paroxysmal positional vertigo.

PubMed

Yang, Won Sun; Kim, Sung Huhn; Lee, Jong Dae; Lee, Won-Sang

2008-12-01

To investigate the vestibular evoked myogenic potentials (VEMPs) resulting in benign paroxysmal positional vertigo (BPPV) patients and to verify its clinical applications in BPPV. A prospective study. Tertiary referral dizziness center. Forty-one patients with diagnosis of BPPV and 92 healthy volunteers who underwent VEMP testing. Patients were treated by canalith repositioning maneuvers according to the affected canal, and testing of VEMP was performed at diagnosis and after treatment. Testing of VEMP was performed in BPPV patients and in the control group. The number of times the canalith repositioning maneuver was repeated until the patient's report of relief from vertigo and findings of negative positioning test were recorded to find out the relationship between VEMP results and the progress of disease. Vestibular evoked myogenic potential results of BPPV patients showed prolonged p13 and n23 latencies compared with those of the control group, and we could not find any significant difference in VEMP latencies between patients with posterior and horizontal canal type of BPPV. The number of times that the maneuver was repeated did not correlate with the degree of latency prolongation, but in the "no response" group, the number of times was considerably greater than that in the "response" group. We found that VEMP latencies are increased in BPPV patients, which may signify neuronal degenerative changes in the macula of the saccule. When an extensive neuronal damage was suspected by VEMP results such as "no response" in VEMP, the disease progress showed a chronic and resistive course. Therefore, we propose that VEMP could be a useful method to determine a clinical prognosis of patients with BPPV.

Vestibular-evoked myogenic potential (VEMP) to evaluate cervical myelopathy in human T-cell lymphotropic virus type I infection.

PubMed

Felipe, Lilian; Gonçalves, Denise Utsch; Santos, Marco Aurélio Rocha; Proietti, Fernando Augusto; Ribas, João Gabriel Ramos; Carneiro-Proietti, Anna Bárbara; Lambertucci, José Roberto

2008-05-15

Cross-seccional analysis. To define the clinical usefulness of vestibular-evoked myogenic potential (VEMP) in detecting cervical medullar involvement related to human T-cell lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP). VEMP is generated by acoustic or galvanic stimuli, passing through the vestibulo-spinal motor tract, the spinal nerves and recorded by means of surface electrodes on the sternocleidomastoid muscle. HAM/TSP is a progressive inflammatory myelopathy with predominant lesions at the thoracic spinal cord level, although the cervical spine can be affected. VEMP may be of value to investigate cervical myelopathy. Seventy-two individuals were evaluated of whom 30 HTLV-1 were seronegative and 42 HTLV-1 seropositive (22 asymptomatic, 10 with complaints of walking difficulty without definite HAM/TSP and 10 with definite HAM/TSP). VEMP was recorded using monaural delivered short tone burst (linear rise-fall 1 millisecond, plateau 2 milliseconds, 1 KHz) 118 dB NA, stimulation rate of 5 Hz, analysis time of 60 milliseconds, 200 stimuli, band pass filtered between 10 and 1.500 Hz. VEMP was normal in the seronegative group (30 controls). In the seropositive, abnormal VEMP was seen in 11 of 22 (50%) of the HTLV-1 asymptomatic carriers, in 7 of 10 (70%) of those with complaints of walking difficulty and in 8 of 10 (80%) of the HAM/TSP patients. In this last group, the pattern of response was different. No VEMP response was more frequent when compared with the HTLV-1 asymptomatic group (2-tailed P-value = 0.001). VEMP may possibly be useful to identify patients with cervical myelopathy and to distinguish variable degrees of functional damage. Minor injury would be related to latency prolongation and major injury to no potential-evoked response.

[Effect of the middle ear status on the recording of vestibular evoked myogenic potential--VEMP].

PubMed

Kurzyna, Agnieszka; Hassmann-Poznańska, Elzbieta; Topolska, Małgorzata Maria

2005-01-01

The aim of this study was to assess the effect of the middle ear status on the recording of air- and bone-conducted vestibular evoked myogenic potential. Forty eight children were included in the study, ranging in age from 4 to 10 years. All of the children underwent otoscopy, pure tone audiometry, tympanometry and air- and bone-conducted VEMP in response to click. There were 3 groups according to the condition of the middle ear: group I--52 ears (type A and C1 tympanogram, pure tone average < or = 20 dB), group II--23 ears (type C2 and B tympanogram, pure tone average < or = 20 dB), group III--21 (type B tympanogram, pure tone average > 20 dB). The threshold, presence of correct waveform morphology of the response and latency was evaluated. The condition of the middle ear has no significant effect on the recording of VEMP and mean level of the response threshold with bone stimulation, based on the performed studies. However, with air stimulation it has effect on the recording of VEMP, increase of the mean threshold response and shortening of latency p13 and n23.

Ethanol exerts dual effects on calcium homeostasis in CCK-8-stimulated mouse pancreatic acinar cells.

PubMed

Fernández-Sánchez, Marcela; del Castillo-Vaquero, Angel; Salido, Ginés M; González, Antonio

2009-10-30

A significant percentage of patients with pancreatitis often presents a history of excessive alcohol consumption. Nevertheless, the patho-physiological effect of ethanol on pancreatitis remains poorly understood. In the present study, we have investigated the early effects of acute ethanol exposure on CCK-8-evoked Ca2+ signals in mouse pancreatic acinar cells. Changes in [Ca2+]i and ROS production were analyzed employing fluorescence techniques after loading cells with fura-2 or CM-H2DCFDA, respectively. Ethanol, in the concentration range from 1 to 50 mM, evoked an oscillatory pattern in [Ca2+]i. In addition, ethanol evoked reactive oxygen species generation (ROS) production. Stimulation of cells with 1 nM or 20 pM CCK-8, respectively led to a transient change and oscillations in [Ca2+]i. In the presence of ethanol a transformation of 20 pM CCK-8-evoked physiological oscillations into a single transient increase in [Ca2+]i in the majority of cells was observed. Whereas, in response to 1 nM CCK-8, the total Ca2+ mobilization was significantly increased by ethanol pre-treatment. Preincubation of cells with 1 mM 4-MP, an inhibitor of alcohol dehydrogenase, or 10 microM of the antioxidant cinnamtannin B-1, reverted the effect of ethanol on total Ca2+ mobilization evoked by 1 nM CCK-8. Cinnamtannin B-1 blocked ethanol-evoked ROS production. ethanol may lead, either directly or through ROS generation, to an over stimulation of pancreatic acinar cells in response to CCK-8, resulting in a higher Ca2+ mobilization compared to normal conditions. The actions of ethanol on CCK-8-stimulation of cells create a situation potentially leading to Ca2+ overload, which is a common pathological precursor that mediates pancreatitis.

Salicylate-Induced Auditory Perceptual Disorders and Plastic Changes in Nonclassical Auditory Centers in Rats

PubMed Central

Chen, Guang-Di; Radziwon, Kelly E.; Manohar, Senthilvelan

2014-01-01

Previous studies have shown that sodium salicylate (SS) activates not only central auditory structures, but also nonauditory regions associated with emotion and memory. To identify electrophysiological changes in the nonauditory regions, we recorded sound-evoked local field potentials and multiunit discharges from the striatum, amygdala, hippocampus, and cingulate cortex after SS-treatment. The SS-treatment produced behavioral evidence of tinnitus and hyperacusis. Physiologically, the treatment significantly enhanced sound-evoked neural activity in the striatum, amygdala, and hippocampus, but not in the cingulate. The enhanced sound evoked response could be linked to the hyperacusis-like behavior. Further analysis showed that the enhancement of sound-evoked activity occurred predominantly at the midfrequencies, likely reflecting shifts of neurons towards the midfrequency range after SS-treatment as observed in our previous studies in the auditory cortex and amygdala. The increased number of midfrequency neurons would lead to a relative higher number of total spontaneous discharges in the midfrequency region, even though the mean discharge rate of each neuron may not increase. The tonotopical overactivity in the midfrequency region in quiet may potentially lead to tonal sensation of midfrequency (the tinnitus). The neural changes in the amygdala and hippocampus may also contribute to the negative effect that patients associate with their tinnitus. PMID:24891959

Spontaneous and evoked release are independently regulated at individual active zones.

PubMed

Melom, Jan E; Akbergenova, Yulia; Gavornik, Jeffrey P; Littleton, J Troy

2013-10-30

Neurotransmitter release from synaptic vesicle fusion is the fundamental mechanism for neuronal communication at synapses. Evoked release following an action potential has been well characterized for its function in activating the postsynaptic cell, but the significance of spontaneous release is less clear. Using transgenic tools to image single synaptic vesicle fusion events at individual release sites (active zones) in Drosophila, we characterized the spatial and temporal dynamics of exocytotic events that occur spontaneously or in response to an action potential. We also analyzed the relationship between these two modes of fusion at single release sites. A majority of active zones participate in both modes of fusion, although release probability is not correlated between the two modes of release and is highly variable across the population. A subset of active zones is specifically dedicated to spontaneous release, indicating a population of postsynaptic receptors is uniquely activated by this mode of vesicle fusion. Imaging synaptic transmission at individual release sites also revealed general rules for spontaneous and evoked release, and indicate that active zones with similar release probability can cluster spatially within individual synaptic boutons. These findings suggest neuronal connections contain two information channels that can be spatially segregated and independently regulated to transmit evoked or spontaneous fusion signals.

Functional abnormalities in the cortical processing of sound complexity and musical consonance in schizophrenia: evidence from an evoked potential study

PubMed Central

2013-01-01

Background Previous studies have demonstrated functional and structural temporal lobe abnormalities located close to the auditory cortical regions in schizophrenia. The goal of this study was to determine whether functional abnormalities exist in the cortical processing of musical sound in schizophrenia. Methods Twelve schizophrenic patients and twelve age- and sex-matched healthy controls were recruited, and participants listened to a random sequence of two kinds of sonic entities, intervals (tritones and perfect fifths) and chords (atonal chords, diminished chords, and major triads), of varying degrees of complexity and consonance. The perception of musical sound was investigated by the auditory evoked potentials technique. Results Our results showed that schizophrenic patients exhibited significant reductions in the amplitudes of the N1 and P2 components elicited by musical stimuli, to which consonant sounds contributed more significantly than dissonant sounds. Schizophrenic patients could not perceive the dissimilarity between interval and chord stimuli based on the evoked potentials responses as compared with the healthy controls. Conclusion This study provided electrophysiological evidence of functional abnormalities in the cortical processing of sound complexity and music consonance in schizophrenia. The preliminary findings warrant further investigations for the underlying mechanisms. PMID:23721126

Paired motor cortex and cervical epidural electrical stimulation timed to converge in the spinal cord promotes lasting increases in motor responses

PubMed Central

Mishra, Asht M.; Pal, Ajay; Gupta, Disha

2017-01-01

Key points Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord.The modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone.Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal.Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord. Abstract Convergent activity in neural circuits can generate changes at their intersection. The rules of paired electrical stimulation are best understood for protocols that stimulate input circuits and their targets. We took a different approach by targeting the interaction of descending motor pathways and large diameter afferents in the spinal cord. We hypothesized that pairing stimulation of motor cortex and cervical spinal cord would strengthen motor responses through their convergence. We placed epidural electrodes over motor cortex and the dorsal cervical spinal cord in rats; motor evoked potentials (MEPs) were measured from biceps. MEPs evoked from motor cortex were robustly augmented with spinal epidural stimulation delivered at an intensity below the threshold for provoking an MEP. Augmentation was critically dependent on the timing and position of spinal stimulation. When the spinal stimulation was timed to coincide with the descending volley from motor cortex stimulation, MEPs were more than doubled. We then tested the effect of repeated pairing of motor cortex and spinal stimulation. Repetitive pairing caused strong augmentation of cortical MEPs and spinal excitability that lasted up to an hour after just 5 min of pairing. Additional physiology experiments support the hypothesis that paired stimulation is mediated by convergence of descending motor circuits and large diameter afferents in the spinal cord. The large effect size of this protocol and the conservation of the circuits being manipulated between rats and humans makes it worth pursuing for recovery of sensorimotor function after injury to the central nervous system. PMID:28752624

Paired motor cortex and cervical epidural electrical stimulation timed to converge in the spinal cord promotes lasting increases in motor responses.

PubMed

Mishra, Asht M; Pal, Ajay; Gupta, Disha; Carmel, Jason B

2017-11-15

Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord. The modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone. Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal. Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord. Convergent activity in neural circuits can generate changes at their intersection. The rules of paired electrical stimulation are best understood for protocols that stimulate input circuits and their targets. We took a different approach by targeting the interaction of descending motor pathways and large diameter afferents in the spinal cord. We hypothesized that pairing stimulation of motor cortex and cervical spinal cord would strengthen motor responses through their convergence. We placed epidural electrodes over motor cortex and the dorsal cervical spinal cord in rats; motor evoked potentials (MEPs) were measured from biceps. MEPs evoked from motor cortex were robustly augmented with spinal epidural stimulation delivered at an intensity below the threshold for provoking an MEP. Augmentation was critically dependent on the timing and position of spinal stimulation. When the spinal stimulation was timed to coincide with the descending volley from motor cortex stimulation, MEPs were more than doubled. We then tested the effect of repeated pairing of motor cortex and spinal stimulation. Repetitive pairing caused strong augmentation of cortical MEPs and spinal excitability that lasted up to an hour after just 5 min of pairing. Additional physiology experiments support the hypothesis that paired stimulation is mediated by convergence of descending motor circuits and large diameter afferents in the spinal cord. The large effect size of this protocol and the conservation of the circuits being manipulated between rats and humans makes it worth pursuing for recovery of sensorimotor function after injury to the central nervous system. © 2017 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Enhanced brainstem and cortical evoked response amplitudes: single-trial covariance analysis.

PubMed

Galbraith, G C

2001-06-01

The purpose of the present study was to develop analytic procedures that improve the definition of sensory evoked response components. Such procedures could benefit all recordings but would especially benefit difficult recordings where many trials are contaminated by muscle and movement artifacts. First, cross-correlation and latency adjustment analyses were applied to the human brainstem frequency-following response and cortical auditory evoked response recorded on the same trials. Lagged cross-correlation functions were computed, for each of 17 subjects, between single-trial data and templates consisting of the sinusoid stimulus waveform for the brainstem response and the subject's own smoothed averaged evoked response P2 component for the cortical response. Trials were considered in the analysis only if the maximum correlation-squared (r2) exceeded .5 (negatively correlated trials were thus included). Identical correlation coefficients may be based on signals with quite different amplitudes, but it is possible to assess amplitude by the nonnormalized covariance function. Next, an algorithm is applied in which each trial with negative covariance is matched to a trial with similar, but positive, covariance and these matched-trial pairs are deleted. When an evoked response signal is present in the data, the majority of trials positively correlate with the template. Thus, a residual of positively correlated trials remains after matched covariance trials are deleted. When these residual trials are averaged, the resulting brainstem and cortical responses show greatly enhanced amplitudes. This result supports the utility of this analysis technique in clarifying and assessing evoked response signals.

Cervical sympathetic block prolongs the latency and reduces the amplitude of trigeminal somatosensory evoked potentials on the contralateral side.

PubMed

Kawaguchi, Jun; Matsuura, Nobuyuki; Kasahara, Masataka; Ichinohe, Tatsuya

2015-02-01

The purpose of this study was to investigate the latency and amplitude of trigeminal somatosensory evoked potentials to clarify how nerve function on the contralateral side is affected after cervical sympathetic block (CSB). Subjects comprised 16 volunteers. For CSB, the tip of a needle was contacted with the transverse process of the sixth cervical vertebra on the right side, and lidocaine was injected. Trigeminal somatosensory evoked potentials were recorded bilaterally from C5/C6 scalp positions. Pupil diameters were also measured. Electrical stimulations were applied to the left-side lower lip, and trigeminal somatosensory evoked potentials waveforms derived from both sides of the scalp were recorded. Then, electrical stimulations were applied to the right-side of the lower lip, and recording was again performed. Recordings were performed at 5, 15, and 30 minutes after CSB. On the CSB side, pupil diameter decreased at 5 and 15 minutes after CSB. Trigeminal somatosensory evoked potentials at contralateral stimulation showed a prolongation of the latency in both P20 and N25 components on bilateral recording sites 5 and 15 minutes after CSB. Trigeminal somatosensory evoked potentials' amplitude at contralateral stimulation was smaller than at ipsilateral stimulation 5 minutes after CSB. Cervical sympathetic block prolongs the latency and reduces the amplitude of trigeminal somatosensory evoked potentials on the contralateral side.

Activation of serotonin 2A receptors underlies the psilocybin-induced effects on α oscillations, N170 visual-evoked potentials, and visual hallucinations.

PubMed

Kometer, Michael; Schmidt, André; Jäncke, Lutz; Vollenweider, Franz X

2013-06-19

Visual illusions and hallucinations are hallmarks of serotonergic hallucinogen-induced altered states of consciousness. Although the serotonergic hallucinogen psilocybin activates multiple serotonin (5-HT) receptors, recent evidence suggests that activation of 5-HT2A receptors may lead to the formation of visual hallucinations by increasing cortical excitability and altering visual-evoked cortical responses. To address this hypothesis, we assessed the effects of psilocybin (215 μg/kg vs placebo) on both α oscillations that regulate cortical excitability and early visual-evoked P1 and N170 potentials in healthy human subjects. To further disentangle the specific contributions of 5-HT2A receptors, subjects were additionally pretreated with the preferential 5-HT2A receptor antagonist ketanserin (50 mg vs placebo). We found that psilocybin strongly decreased prestimulus parieto-occipital α power values, thus precluding a subsequent stimulus-induced α power decrease. Furthermore, psilocybin strongly decreased N170 potentials associated with the appearance of visual perceptual alterations, including visual hallucinations. All of these effects were blocked by pretreatment with the 5-HT2A antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin profoundly modulates the neurophysiological and phenomenological indices of visual processing. Specifically, activation of 5-HT2A receptors may induce a processing mode in which stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation through the modulation of α oscillations. Furthermore, the observed reduction of N170 visual-evoked potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations. This change in N170 potentials may be important not only for psilocybin-induced states but also for understanding acute hallucinatory states seen in psychiatric disorders, such as schizophrenia and Parkinson's disease.

Functional MRI Detection of Hemodynamic Response of Repeated Median Nerve Stimulation

PubMed Central

Ai, Leo; Oya, Hiroyuki; Howard, Matthew; Xiong, Jinhu

2012-01-01

Median nerve stimulation is a commonly used technique in the clinical setting to determine areas of neuronal function in the brain. Neuronal activity of repeated median nerve stimulation is well studied. The cerebral hemodynamic response of the stimulation, on the other hand, is not very clear. In this study, we investigate how cerebral hemodynamics behaves over time using the same repeated median nerve stimulation. Ten subjects received constant repeated electrical stimulation to the right median nerve. Each subject had fMRI scans while receiving said stimulations for seven runs. Our results show that the BOLD signal significantly decreases across each run. Significant BOLD signal decreases can also be seen within runs. These results are consistent with studies that have studied the hemodynamic habituation effect with other forms of stimulation. However, the results do not completely agree with the findings of studies where evoked potentials were examined. Thus, further inquiry of how evoked potentials and cerebral hemodynamics are coupled when using constant stimulations is needed. PMID:23228312

The relationship between obligatory cortical auditory evoked potentials (CAEPs) and functional measures in young infants.

PubMed

Golding, Maryanne; Pearce, Wendy; Seymour, John; Cooper, Alison; Ching, Teresa; Dillon, Harvey

2007-02-01

Finding ways to evaluate the success of hearing aid fittings in young infants has increased in importance with the implementation of hearing screening programs. Cortical auditory evoked potentials (CAEP) can be recorded in infants and provides evidence for speech detection at the cortical level. The validity of this technique as a tool of hearing aid evaluation needs, however, to be demonstrated. The present study examined the relationship between the presence/absence of CAEPs to speech stimuli and the outcomes of a parental questionnaire in young infants who were fitted with hearing aids. The presence/absence of responses was determined by an experienced examiner as well as by a statistical measure, Hotelling's T(2). A statistically significant correlation between CAEPs and questionnaire scores was found using the examiner's grading (rs = 0.45) and using the statistical grading (rs = 0.41), and there was reasonably good agreement between traditional response detection methods and the statistical analysis.

Comparison of evoked potentials in the same hand in normal subjects and in patients with carpal tunnel syndrome.

PubMed

Felsenthal, G

1978-10-01

The amplitude of the evoked median and ulnar sensory action potential (SAP) was measured in fifty normal volunteers (4) and median and ulnar SAP in opposite hands were compared. In addition, the amplitude of the median response was compared to the ulnar response. It was found that the lower limit of the range of observations for the median amplitude was 20 muV, the range of observations for the median/median SAP ratio was 50--100%, and that in only 3 observations out of 100 normal hands was the median/ulnar SAP ratio less than 80%. In a series of 60 patients with carpal tunnel syndrome (CTS), 22 had bilateral involvement. The median SAP was obtainable in 62 of these diagnosed cases of CTS. Forty of these 62 cases could be identified by one of the three amplitude criteria: median SAP of less than 20 muV; median/median amplitude percentage of less than 50%; or a median/ulnar amplitude of less than 80%.

Robustness of sensory-evoked excitation is increased by inhibitory inputs to distal apical tuft dendrites

PubMed Central

Egger, Robert; Schmitt, Arno C.; Wallace, Damian J.; Sakmann, Bert; Oberlaender, Marcel; Kerr, Jason N. D.

2015-01-01

Cortical inhibitory interneurons (INs) are subdivided into a variety of morphologically and functionally specialized cell types. How the respective specific properties translate into mechanisms that regulate sensory-evoked responses of pyramidal neurons (PNs) remains unknown. Here, we investigated how INs located in cortical layer 1 (L1) of rat barrel cortex affect whisker-evoked responses of L2 PNs. To do so we combined in vivo electrophysiology and morphological reconstructions with computational modeling. We show that whisker-evoked membrane depolarization in L2 PNs arises from highly specialized spatiotemporal synaptic input patterns. Temporally L1 INs and L2–5 PNs provide near synchronous synaptic input. Spatially synaptic contacts from L1 INs target distal apical tuft dendrites, whereas PNs primarily innervate basal and proximal apical dendrites. Simulations of such constrained synaptic input patterns predicted that inactivation of L1 INs increases trial-to-trial variability of whisker-evoked responses in L2 PNs. The in silico predictions were confirmed in vivo by L1-specific pharmacological manipulations. We present a mechanism—consistent with the theory of distal dendritic shunting—that can regulate the robustness of sensory-evoked responses in PNs without affecting response amplitude or latency. PMID:26512104

Populations of striatal medium spiny neurons encode vibrotactile frequency in rats: modulation by slow wave oscillations

PubMed Central

Hawking, Thomas G.

2013-01-01

Dorsolateral striatum (DLS) is implicated in tactile perception and receives strong projections from somatosensory cortex. However, the sensory representations encoded by striatal projection neurons are not well understood. Here we characterized the contribution of DLS to the encoding of vibrotactile information in rats by assessing striatal responses to precise frequency stimuli delivered to a single vibrissa. We applied stimuli in a frequency range (45–90 Hz) that evokes discriminable percepts and carries most of the power of vibrissa vibration elicited by a range of complex fine textures. Both medium spiny neurons and evoked potentials showed tactile responses that were modulated by slow wave oscillations. Furthermore, medium spiny neuron population responses represented stimulus frequency on par with previously reported behavioral benchmarks. Our results suggest that striatum encodes frequency information of vibrotactile stimuli which is dynamically modulated by ongoing brain state. PMID:23114217

Distinction between added-energy and phase-resetting mechanisms in non-invasively detected somatosensory evoked responses.

PubMed

Fedele, T; Scheer, H-J; Burghoff, M; Waterstraat, G; Nikulin, V V; Curio, G

2013-01-01

Non-invasively recorded averaged event-related potentials (ERP) represent a convenient opportunity to investigate human brain perceptive and cognitive processes. Nevertheless, generative ERP mechanisms are still debated. Two previous approaches have been contested in the past: the added-energy model in which the response raises independently from the ongoing background activity, and the phase-reset model, based on stimulus-driven synchronization of oscillatory ongoing activity. Many criteria for the distinction of these two models have been proposed, but there is no definitive methodology to disentangle them, owing also to the limited information at the single trial level. Here, we propose a new approach combining low-noise EEG technology and multivariate decomposition techniques. We present theoretical analyses based on simulated data and identify in high-frequency somatosensory evoked responses an optimal target for the distinction between the two mechanisms.

Click- and chirp-evoked human compound action potentials

PubMed Central

Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

2010-01-01

In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213–2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obtained from derived compound band action potentials provided by Eggermont [(1979). J. Acoust. Soc. Am. 65, 463–470]. CAPs were recorded from an electrode placed on the tympanic membrane (TM), and the acoustic signals were monitored with a probe tube microphone attached to the TM electrode. Results showed that the amplitude and latency of chirp-evoked N1 of the CAP differed from click-evoked CAPs in several regards. For the chirp-evoked CAP, the N1 amplitude was significantly larger than the click-evoked N1s. The latency-intensity function was significantly shallower for chirp-evoked CAPs as compared to click-evoked CAPs. This suggests that auditory nerve fibers respond with more unison to a chirp stimulus than to a click stimulus. PMID:21117748

Cervical intraspinal microstimulation evokes robust forelimb movements before and after injury

NASA Astrophysics Data System (ADS)

Sunshine, Michael D.; Cho, Frances S.; Lockwood, Danielle R.; Fechko, Amber S.; Kasten, Michael R.; Moritz, Chet T.

2013-06-01

Objective. Intraspinal microstimulation (ISMS) is a promising method for reanimating paralyzed limbs following neurological injury. ISMS within the cervical and lumbar spinal cord is capable of evoking a variety of highly-functional movements prior to injury, but the ability of ISMS to evoke forelimb movements after cervical spinal cord injury is unknown. Here we examine the forelimb movements and muscles activated by cervical ISMS both before and after contusion injury. Approach. We documented the forelimb muscles activated and movements evoked via systematic stimulation of the rodent cervical spinal cord both before injury and three, six and nine weeks following a moderate C4/C5 lateralized contusion injury. Animals were anesthetized with isoflurane to permit construction of somatotopic maps of evoked movements and quantify evoked muscle synergies between cervical segments C3 and T1. Main results. When ISMS was delivered to the cervical spinal cord, a variety of responses were observed at 68% of locations tested, with a spatial distribution that generally corresponded to the location of motor neuron pools. Stimulus currents required to achieve movement and the number of sites where movements could be evoked were unchanged by spinal cord injury. A transient shift toward extension-dominated movements and restricted muscle synergies were observed at three and six weeks following injury, respectively. By nine weeks after injury, however, ISMS-evoked patterns were similar to spinally-intact animals. Significance. The results demonstrate the potential for cervical ISMS to reanimate hand and arm function following spinal cord injury. Robust forelimb movements can be evoked both before and during the chronic stages of recovery from a clinically relevant and sustained cervical contusion injury.

Effects of hypoxia on sympathetic neural control in humans

NASA Technical Reports Server (NTRS)

Smith, M. L.; Muenter, N. K.

2000-01-01

This special issue is principally focused on the time domain of the adaptive mechanisms of ventilatory responses to short-term, long-term and intermittent hypoxia. The purpose of this review is to summarize the limited literature on the sympathetic neural responses to sustained or intermittent hypoxia in humans and attempt to discern the time domain of these responses and potential adaptive processes that are evoked during short and long-term exposures to hypoxia.

[The influence of various acoustic stimuli upon the cumulative action potential (SAP) of the auditory nerves in guinea pigs (author's transl)].

PubMed

Hofmann, G; Kraak, W

1976-08-31

The impact of various acoustic stimuli upon the cumulative action potential of the auditory nerves in guinea pigs is investigated by means of the averaging method. It was found that the potential amplitude within the measuring range increases with the logarithm of the rising sonic pressure velocity. Unlike the evoked response audiometry (ERA), this potential seems unsuitable for furnishing information of the frequency-dependent threshold course.

Comparison of tone burst versus logon stimulation for vestibular evoked myogenic potentials.

PubMed

Ozdek, Ali; Bayır, Omer; Tatar, Emel Cadallı; Korkmaz, Mehmet Hakan

2012-05-01

The following study has been carried out to compare the effectiveness of logon and tone burst acoustic stimulation to elicit vestibular evoked myogenic potential (VEMP) responses. The methods and the subjects include 31 healthy adult volunteers (62 ears) who were enrolled in this study. Two different acoustic stimuli, logon (L-VEMP) and tone burst (T-VEMP), were used to elicit VEMP responses in each subject. Bilateral recordings with simultaneous binaural acoustic stimulations were used during VEMP recordings. During the recording period, the subjects were in supine position with their head elevated. The results observed were that the response rate of p1n1 wave was 91.9% for L-VEMP and 88.7% for T-VEMP. The response rate of n2p2 wave was 80.6% for L-VEMP, and 75.8% for T-VEMP. There were no significant differences between the two groups with respect to the latencies of p1, n1, n2 and p2, p1n1 and n2p2 interval, and p1n1 and n2p2 amplitude. The conclusion was that there was no difference between logon and tone burst stimulation with respect to VEMP response rates and VEMP parameters. Therefore, they are not superior to each other.

Sensitivity of bronchopulmonary receptors to cold and heat mediated by transient receptor potential cation channel subtypes in an ex vivo rat lung preparation.

PubMed

Zhou, Yun; Sun, Biying; Li, Qian; Luo, Pin; Dong, Li; Rong, Weifang

2011-08-15

Changes in airway temperature can result in respiratory responses such as cough, bronchoconstriction and mucosal secretion after cold exposure and hyperventilation after heat exposure. In the present investigation, we examined the activity of bronchopulmonary receptors in response to activators of thermo-sensitive transient receptor potential (TS-TRP) cation channels using an ex vivo rat lung preparation. Receptive fields in small bronchioles were probed with von Frey hair monofilaments, warm (50°C) or cold (8°C) saline or saline containing TS-TRP agonists. Among 233 fibers tested, 159 (68.2%) responded to heat (50°C). A large proportion of heat-responsive receptors (107/145) were also activated by capsaicin. Heat and capsaicin-evoked responses were both blocked by TRPV1 antagonist, capsazepine. Only 15.3% of airway receptors responded to cold, which was associated with sensitivity to TRPM8 agonist menthol but not to TRPA1 agonist cinnamaldehyde (CA). Moreover, cold-evoked responses was unaffected by TRPA1 antagonist HC-03001. Our observations suggest that TRPV1 and TRPM8 are involved in transducing heat and cold in the lower respiratory tract, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Occlusion of pressor responses to posterior diencephalic stimulation and muscular contraction.

PubMed

Rybicki, K J; Stremel, R W; Iwamoto, G A; Mitchell, J H; Kaufman, M P

1989-02-01

Although neural occlusion has been suggested to occur between the central and reflex mechanisms increasing arterial pressure, evidence consistent with this phenomenon is lacking. To assess the possibility of neural occlusion we recorded, in chloralose-anesthetized cats, the pressor responses to statically contracting the hindlimb muscles and to electrically stimulating histologically confirmed sites in the posterior hypothalamus and subthalamus. We also recorded the pressor responses to topical application of capsaicin onto the intestine and to stimulation of these diencephalic sites. The pressor responses to simultaneous static contraction and diencephalic stimulation were significantly smaller than the algebraic sum of the pressor responses to contraction and diencephalic stimulation evoked separately. Likewise, the pressor responses to simultaneous capsaicin application and diencephalic stimulation were significantly smaller than the algebraic sum of the responses evoked separately. High intensity stimulation of the L7 dorsal root or the diencephalic sites evoked pressor responses similar in magnitude to the algebraic sum of the two responses evoked separately; thus, the inability of the simultaneous maneuvers to evoke pressor responses that summed algebraically was not due to the fact that they caused a maximal effect. Our findings are consistent with the hypothesis that neural occlusion occurs during stimulation of the posterior diencephalon and static muscular contraction.

Whole person-evoked fMRI activity patterns in human fusiform gyrus are accurately modeled by a linear combination of face- and body-evoked activity patterns

PubMed Central

Kaiser, Daniel; Strnad, Lukas; Seidl, Katharina N.; Kastner, Sabine

2013-01-01

Visual cues from the face and the body provide information about another's identity, emotional state, and intentions. Previous neuroimaging studies that investigated neural responses to (bodiless) faces and (headless) bodies have reported overlapping face- and body-selective brain regions in right fusiform gyrus (FG). In daily life, however, faces and bodies are typically perceived together and are effortlessly integrated into the percept of a whole person, raising the possibility that neural responses to whole persons are qualitatively different than responses to isolated faces and bodies. The present study used fMRI to examine how FG activity in response to a whole person relates to activity in response to the same face and body but presented in isolation. Using multivoxel pattern analysis, we modeled person-evoked response patterns in right FG through a linear combination of face- and body-evoked response patterns. We found that these synthetic patterns were able to accurately approximate the response patterns to whole persons, with face and body patterns each adding unique information to the response patterns evoked by whole person stimuli. These results suggest that whole person responses in FG primarily arise from the coactivation of independent face- and body-selective neural populations. PMID:24108794

Synaptic potentials in respiratory neurones during evoked phase switching after NMDA receptor blockade in the cat

PubMed Central

Pierrefiche, O; Haji, A; Foutz, A S; Takeda, R; Champagnat, J; Denavit-Saubié, M

1998-01-01

Blockade of NMDA receptors by dizocilpine impairs the inspiratory off-switch (IOS) of central origin but not the IOS evoked by stimulation of sensory afferents. To investigate whether this difference was due to the effects of different patterns of synaptic interactions on respiratory neurones, we stimulated electrically the superior laryngeal nerve (SLN) or vagus nerve in decerebrate cats before and after i.v. administration of dizocilpine, whilst recording intracellularly. Phrenic nerve responses to ipsilateral SLN or vagal stimulation were: at mid-inspiration, a transient inhibition often followed by a brief burst of activity; at late inspiration, an IOS; and at mid-expiration, a late burst of activity. In all neurones (n = 16), SLN stimulation at mid-inspiration evoked an early EPSP during phase 1 (latency to the arrest of phrenic nerve activity), followed by an IPSP in inspiratory (I) neurones (n = 8) and by a wave of EPSPs in post-inspiratory (PI) neurones (n = 8) during phase 2 (inhibition of phrenic activity). An EPSP in I neurones and an IPSP in PI neurones occurred during phase 3 (brief phrenic burst) following phase 2. Evoked IOS was associated with a fast (phase 1) activation of PI neurones, whereas during spontaneous IOS, a progressive (30-50 ms) depolarization of PI neurones preceded the arrest of phrenic activity. Phase 3 PSPs were similar to those occurring during the burst of activity seen at the start of spontaneous inspiration. Dizocilpine did not suppress the evoked phrenic inhibition and the late burst of activity. The shapes and timing of the evoked PSPs and the changes in membrane potential in I and PI neurones during the phase transition were not altered. We hypothesize that afferent sensory pathways not requiring NMDA receptors (1) terminate inspiration through a premature activation of PI neurones, and (2) evoke a late burst of phrenic activity which might be the first stage of the inspiratory on-switch. PMID:9508816

[The algorithms and development for the extraction of evoked potentials].

PubMed

Niu, Jie; Qiu, Tianshuang

2004-06-01

The extraction of evoked potentials is a main subject in the area of brain signal processing. In recent years, the single-trial extraction of evoked potentials has been focused on by many studies. In this paper, the approaches based on the wavelet transform, the neural network, the high order acumulants and the independent component analysis are briefly reviewed.

[Application of evoked potentials monitoring in total thoracoabdominal aorta aneurysm repair].

PubMed

Duan, Y Y; Zheng, J; Pan, X D; Zhu, J M; Liu, Y M; Ge, Y P; Cheng, L J; Sun, L Z

2016-04-05

To evaluate the application value of evoked potentials (EP) monitoring in patients undergoing aorta-iliac bypass for total thoracoabdominal aorta aneurysm repair (tTAAAR). A prospective study, with a total of 31 patients undergoing tTAAAR and intraoperative EP monitoring from June 2014 to April 2015 was carried out. The results of intraoperative evoked potentials, clinical outcomes and follow-up data of patients were collected for further evaluation. The EP wave disappeared [motor evoked potentials for (55.6±18.1) min, somatosensory evoked potentials for (50.3±18.7) min] after proximal descending aorta being clamped, and gradually recovered after the segment arteries of spine cord were reconstructed. The EP wave was restored to normal level at the end of operation in all the cases. The somatosensory evoked potentials remained unchanged in 2 cases (false negative). One case died after operation. No spinal cord injury occurred. The median follow-up after operation was 10 months (5-14 months). There was no delayed neurological deficit. EP provided an on-line monitoring of the condition of spinal cord function, which become an intraoperative protocol to avoid the irreversible injury of spinal cord.

On wavelet analysis of auditory evoked potentials.

PubMed

Bradley, A P; Wilson, W J

2004-05-01

To determine a preferred wavelet transform (WT) procedure for multi-resolution analysis (MRA) of auditory evoked potentials (AEP). A number of WT algorithms, mother wavelets, and pre-processing techniques were examined by way of critical theoretical discussion followed by experimental testing of key points using real and simulated auditory brain-stem response (ABR) waveforms. Conclusions from these examinations were then tested on a normative ABR dataset. The results of the various experiments are reported in detail. Optimal AEP WT MRA is most likely to occur when an over-sampled discrete wavelet transformation (DWT) is used, utilising a smooth (regularity >or=3) and symmetrical (linear phase) mother wavelet, and a reflection boundary extension policy. This study demonstrates the practical importance of, and explains how to minimize potential artefacts due to, 4 inter-related issues relevant to AEP WT MRA, namely shift variance, phase distortion, reconstruction smoothness, and boundary artefacts.

Delayed P100-Like Latencies in Multiple Sclerosis: A Preliminary Investigation Using Visual Evoked Spread Spectrum Analysis

PubMed Central

Kiiski, Hanni S. M.; Ní Riada, Sinéad; Lalor, Edmund C.; Gonçalves, Nuno R.; Nolan, Hugh; Whelan, Robert; Lonergan, Róisín; Kelly, Siobhán; O'Brien, Marie Claire; Kinsella, Katie; Bramham, Jessica; Burke, Teresa; Ó Donnchadha, Seán; Hutchinson, Michael; Tubridy, Niall; Reilly, Richard B.

2016-01-01

Conduction along the optic nerve is often slowed in multiple sclerosis (MS). This is typically assessed by measuring the latency of the P100 component of the Visual Evoked Potential (VEP) using electroencephalography. The Visual Evoked Spread Spectrum Analysis (VESPA) method, which involves modulating the contrast of a continuous visual stimulus over time, can produce a visually evoked response analogous to the P100 but with a higher signal-to-noise ratio and potentially higher sensitivity to individual differences in comparison to the VEP. The main objective of the study was to conduct a preliminary investigation into the utility of the VESPA method for probing and monitoring visual dysfunction in multiple sclerosis. The latencies and amplitudes of the P100-like VESPA component were compared between healthy controls and multiple sclerosis patients, and multiple sclerosis subgroups. The P100-like VESPA component activations were examined at baseline and over a 3-year period. The study included 43 multiple sclerosis patients (23 relapsing-remitting MS, 20 secondary-progressive MS) and 42 healthy controls who completed the VESPA at baseline. The follow-up sessions were conducted 12 months after baseline with 24 MS patients (15 relapsing-remitting MS, 9 secondary-progressive MS) and 23 controls, and again at 24 months post-baseline with 19 MS patients (13 relapsing-remitting MS, 6 secondary-progressive MS) and 14 controls. The results showed P100-like VESPA latencies to be delayed in multiple sclerosis compared to healthy controls over the 24-month period. Secondary-progressive MS patients had most pronounced delay in P100-like VESPA latency relative to relapsing-remitting MS and controls. There were no longitudinal P100-like VESPA response differences. These findings suggest that the VESPA method is a reproducible electrophysiological method that may have potential utility in the assessment of visual dysfunction in multiple sclerosis. PMID:26726800

Relationship between endolymphatic hydrops and vestibular-evoked myogenic potential.

PubMed

Katayama, Naomi; Yamamoto, Masako; Teranishi, Masaaki; Naganawa, Shinji; Nakata, Seiichi; Sone, Michihiko; Nakashima, Tsutomu

2010-08-01

Vestibular-evoked myogenic potential (VEMP) can be used to examine endolymphatic hydrops, especially in the vestibule. To investigate the relationship between the degree of endolymphatic hydrops revealed by magnetic resonance imaging (MRI) and VEMP. Gadolinium diluted with saline was injected intratympanically in 49 ears (40 patients). One day after the injection, the endolymphatic space in the vestibule and the cochlea was visualized by 3 Tesla MRI. A VEMP test was done, and VEMP was judged as absent when the VEMP was within the noise level. VEMP was present in 21 ears and absent in 28 ears. Endolymphatic hydrops was significantly associated with the disappearance of VEMP. Endolymphatic hydrops in the vestibule had a stronger effect than endolymphatic hydrops in the cochlea. Five patients with extremely large vestibular hydrops showed no response of VEMP.

Intracortical circuits amplify sound-evoked activity in primary auditory cortex following systemic injection of salicylate in the rat

PubMed Central

Chrostowski, Michael; Salvi, Richard J.; Allman, Brian L.

2012-01-01

A high dose of sodium salicylate temporarily induces tinnitus, mild hearing loss, and possibly hyperacusis in humans and other animals. Salicylate has well-established effects on cochlear function, primarily resulting in the moderate reduction of auditory input to the brain. Despite decreased peripheral sensitivity and output, salicylate induces a paradoxical enhancement of the sound-evoked field potential at the level of the primary auditory cortex (A1). Previous electrophysiologic studies have begun to characterize changes in thalamorecipient layers of A1; however, A1 is a complex neural circuit with recurrent intracortical connections. To describe the effects of acute systemic salicylate treatment on both thalamic and intracortical sound-driven activity across layers of A1, we applied current-source density (CSD) analysis to field potentials sampled across cortical layers in the anesthetized rat. CSD maps were normally characterized by a large, short-latency, monosynaptic, thalamically driven sink in granular layers followed by a lower amplitude, longer latency, polysynaptic, intracortically driven sink in supragranular layers. Following systemic administration of salicylate, there was a near doubling of both granular and supragranular sink amplitudes at higher sound levels. The supragranular sink amplitude input/output function changed from becoming asymptotic at approximately 50 dB to sharply nonasymptotic, often dominating the granular sink amplitude at higher sound levels. The supragranular sink also exhibited a significant decrease in peak latency, reflecting an acceleration of intracortical processing of the sound-evoked response. Additionally, multiunit (MU) activity was altered by salicylate; the normally onset/sustained MU response type was transformed into a primarily onset response type in granular and infragranular layers. The results from CSD analysis indicate that salicylate significantly enhances sound-driven response via intracortical circuits. PMID:22496535

Independent component analysis for cochlear implant artifacts attenuation from electrically evoked auditory steady-state response measurements

NASA Astrophysics Data System (ADS)

Deprez, Hanne; Gransier, Robin; Hofmann, Michael; van Wieringen, Astrid; Wouters, Jan; Moonen, Marc

2018-02-01

Objective. Electrically evoked auditory steady-state responses (EASSRs) are potentially useful for objective cochlear implant (CI) fitting and follow-up of the auditory maturation in infants and children with a CI. EASSRs are recorded in the electro-encephalogram (EEG) in response to electrical stimulation with continuous pulse trains, and are distorted by significant CI artifacts related to this electrical stimulation. The aim of this study is to evaluate a CI artifacts attenuation method based on independent component analysis (ICA) for three EASSR datasets. Approach. ICA has often been used to remove CI artifacts from the EEG to record transient auditory responses, such as cortical evoked auditory potentials. Independent components (ICs) corresponding to CI artifacts are then often manually identified. In this study, an ICA based CI artifacts attenuation method was developed and evaluated for EASSR measurements with varying CI artifacts and EASSR characteristics. Artifactual ICs were automatically identified based on their spectrum. Main results. For 40 Hz amplitude modulation (AM) stimulation at comfort level, in high SNR recordings, ICA succeeded in removing CI artifacts from all recording channels, without distorting the EASSR. For lower SNR recordings, with 40 Hz AM stimulation at lower levels, or 90 Hz AM stimulation, ICA either distorted the EASSR or could not remove all CI artifacts in most subjects, except for two of the seven subjects tested with low level 40 Hz AM stimulation. Noise levels were reduced after ICA was applied, and up to 29 ICs were rejected, suggesting poor ICA separation quality. Significance. We hypothesize that ICA is capable of separating CI artifacts and EASSR in case the contralateral hemisphere is EASSR dominated. For small EASSRs or large CI artifact amplitudes, ICA separation quality is insufficient to ensure complete CI artifacts attenuation without EASSR distortion.

Dopamine D2 receptors preferentially regulate the development of light responses of the inner retina

PubMed Central

Tian, Ning; Xu, Hong-ping; Wang, Ping

2014-01-01

Retinal light responsiveness measured via electroretinography undergoes developmental modulation and is thought to be critically regulated by both visual experience and dopamine. The primary goal of this study is to determine whether the dopamine D2 receptor regulates the visual experience-dependent functional development of the retina. Accordingly, we recorded electroretinograms from wild type mice and mice with a genetic deletion of the gene that encodes the dopamine D2 receptor raised under normal cyclic light conditions and constant darkness. Our results demonstrate that mutation of the dopamine D2 receptors preferentially increases the amplitude of the inner retinal light responses evoked by high intensity light measured as oscillatory potentials in adult mice. During postnatal development, all three major components of electroretinograms, the a-wave, b-wave and oscillatory potentials, increase with age. Comparatively, mutation of the dopamine D2 receptors preferentially reduces the age-dependent increase of b-waves evoked by low intensity light. Light deprivation from birth reduces the amplitude of b-waves and completely diminishes the increased amplitude of oscillatory potentials. Taken together, these results demonstrate that the dopamine D2 receptor plays an important role in the activity-dependent functional development of the mouse retina. PMID:25393815

The correlation dimension: a useful objective measure of the transient visual evoked potential?

PubMed

Boon, Mei Ying; Henry, Bruce I; Suttle, Catherine M; Dain, Stephen J

2008-01-14

Visual evoked potentials (VEPs) may be analyzed by examination of the morphology of their components, such as negative (N) and positive (P) peaks. However, methods that rely on component identification may be unreliable when dealing with responses of complex and variable morphology; therefore, objective methods are also useful. One potentially useful measure of the VEP is the correlation dimension. Its relevance to the visual system was investigated by examining its behavior when applied to the transient VEP in response to a range of chromatic contrasts (42%, two times psychophysical threshold, at psychophysical threshold) and to the visually unevoked response (zero contrast). Tests of nonlinearity (e.g., surrogate testing) were conducted. The correlation dimension was found to be negatively correlated with a stimulus property (chromatic contrast) and a known linear measure (the Fourier-derived VEP amplitude). It was also found to be related to visibility and perception of the stimulus such that the dimension reached a maximum for most of the participants at psychophysical threshold. The latter suggests that the correlation dimension may be useful as a diagnostic parameter to estimate psychophysical threshold and may find application in the objective screening and monitoring of congenital and acquired color vision deficiencies, with or without associated disease processes.

Towards neural correlates of auditory stimulus processing: A simultaneous auditory evoked potentials and functional magnetic resonance study using an odd-ball paradigm

PubMed Central

Milner, Rafał; Rusiniak, Mateusz; Lewandowska, Monika; Wolak, Tomasz; Ganc, Małgorzata; Piątkowska-Janko, Ewa; Bogorodzki, Piotr; Skarżyński, Henryk

2014-01-01

Background The neural underpinnings of auditory information processing have often been investigated using the odd-ball paradigm, in which infrequent sounds (deviants) are presented within a regular train of frequent stimuli (standards). Traditionally, this paradigm has been applied using either high temporal resolution (EEG) or high spatial resolution (fMRI, PET). However, used separately, these techniques cannot provide information on both the location and time course of particular neural processes. The goal of this study was to investigate the neural correlates of auditory processes with a fine spatio-temporal resolution. A simultaneous auditory evoked potentials (AEP) and functional magnetic resonance imaging (fMRI) technique (AEP-fMRI), together with an odd-ball paradigm, were used. Material/Methods Six healthy volunteers, aged 20–35 years, participated in an odd-ball simultaneous AEP-fMRI experiment. AEP in response to acoustic stimuli were used to model bioelectric intracerebral generators, and electrophysiological results were integrated with fMRI data. Results fMRI activation evoked by standard stimuli was found to occur mainly in the primary auditory cortex. Activity in these regions overlapped with intracerebral bioelectric sources (dipoles) of the N1 component. Dipoles of the N1/P2 complex in response to standard stimuli were also found in the auditory pathway between the thalamus and the auditory cortex. Deviant stimuli induced fMRI activity in the anterior cingulate gyrus, insula, and parietal lobes. Conclusions The present study showed that neural processes evoked by standard stimuli occur predominantly in subcortical and cortical structures of the auditory pathway. Deviants activate areas non-specific for auditory information processing. PMID:24413019

Contribution of Vestibular-Evoked Myogenic Potential (VEMP) testing in the assessment and the differential diagnosis of otosclerosis.

PubMed

Tramontani, Ourania; Gkoritsa, Eleni; Ferekidis, Eleftherios; Korres, Stavros G

2014-02-07

The aim of this prospective clinical study was to evaluate the clinical importance of Vestibular-Evoked Myogenic Potentials (VEMPs) in the assessment and differential diagnosis of otosclerosis and otologic diseases characterized by "pseudo-conductive" components. We also investigated the clinical appearance of balance disorders in patients with otosclerosis by correlating VEMP results with the findings of caloric testing and pure tone audiometry(PTA). Air-conducted(AC) 4-PTA, bone-conducted(BC) 4-PTA, air-bone Gap(ABG), AC, BC tone burst evoked VEMP, and calorics were measured preoperatively in 126 otosclerotic ears. The response rate of the AC-VEMPs and BC-VEMPs was 29.36% and 44.03%, respectively. Statistical differences were found between the means of ABG, AC 4-PTA, and BC 4-PTA in the otosclerotic ears in relation to AC-VEMP elicitability. About one-third of patients presented with disequilibrium. A statistically significant interaction was found between calorics and dizziness in relation to PTA thresholds. No relationship was found between calorics and dizziness with VEMPs responses. AC and BC VEMPs can be elicited in ears with otosclerosis. AC-VEMP is more vulnerable to conductive hearing loss. Evaluation of AC-VEMP thresholds can be added in the diagnostic work-up of otosclerosis in case of doubt, enhancing differential diagnosis in patients with air-bone gaps. Otosclerosis is not a cause of canal paresis or vertigo.

An experimental model for the study of cognitive disorders: the hippocampus and associative learning in mice.

PubMed

Delgado-García, José M; Gruart, Agnès

2008-12-01

The availability of transgenic mice mimicking selective human neurodegenerative and psychiatric disorders calls for new electrophysiological and microstimulation techniques capable of being applied in vivo in this species. In this article, we will concentrate on experiments and techniques developed in our laboratory during the past few years. Thus we have developed different techniques for the study of learning and memory capabilities of wild-type and transgenic mice with deficits in cognitive functions, using classical conditioning procedures. These techniques include different trace (tone/SHOCK and shock/SHOCK) conditioning procedures ? that is, a classical conditioning task involving the cerebral cortex, including the hippocampus. We have also developed implantation and recording techniques for evoking long-term potentiation (LTP) in behaving mice and for recording the evolution of field excitatory postsynaptic potentials (fEPSP) evoked in the hippocampal CA1 area by the electrical stimulation of the commissural/Schaffer collateral pathway across conditioning sessions. Computer programs have also been developed to quantify the appearance and evolution of eyelid conditioned responses and the slope of evoked fEPSPs. According to the present results, the in vivo recording of the electrical activity of selected hippocampal sites during classical conditioning of eyelid responses appears to be a suitable experimental procedure for studying learning capabilities in genetically modified mice, and an excellent model for the study of selected neuropsychiatric disorders compromising cerebral cortex functioning.

Sunlight irradiance and habituation of visual evoked potentials in migraine: The environment makes its mark.

PubMed

Lisicki, Marco; D'Ostilio, Kevin; Erpicum, Michel; Schoenen, Jean; Magis, Delphine

2017-01-01

Background Migraine is a complex multifactorial disease that arises from the interaction between a genetic predisposition and an enabling environment. Habituation is considered as a fundamental adaptive behaviour of the nervous system that is often impaired in migraine populations. Given that migraineurs are hypersensitive to light, and that light deprivation is able to induce functional changes in the visual cortex recognizable through visual evoked potentials habituation testing, we hypothesized that regional sunlight irradiance levels could influence the results of visual evoked potentials habituation studies performed in different locations worldwide. Methods We searched the literature for visual evoked potentials habituation studies comparing healthy volunteers and episodic migraine patients and correlated their results with levels of local solar radiation. Results After reviewing the literature, 26 studies involving 1291 participants matched our inclusion criteria. Deficient visual evoked potentials habituation in episodic migraine patients was reported in 19 studies. Mean yearly sunlight irradiance was significantly higher in locations of studies reporting deficient habituation. Correlation analyses suggested that visual evoked potentials habituation decreases with increasing sunlight irradiance in migraine without aura patients. Conclusion Results from this hypothesis generating analysis suggest that variations in sunlight irradiance may induce adaptive modifications in visual processing systems that could be reflected in visual evoked potentials habituation, and thus partially account for the difference in results between studies performed in geographically distant centers. Other causal factors such as genetic differences could also play a role, and therefore well-designed prospective trials are warranted.

Spinal NMDA-receptor dependent amplification of nociceptive transmission to rat primary somatosensory cortex (SI).

PubMed

Kalliomäki, Jarkko; Granmo, Marcus; Schouenborg, Jens

2003-07-01

The role of NMDA mechanisms in spinal pathways mediating acute nociceptive input to the somatosensory cortex is not clear. In this study, the effect of NMDA-antagonists on nociceptive C fibre transmission to the primary somatosensory cortex (SI) was investigated. Cortical field potentials evoked by CO(2)-laser stimulation of the skin were recorded in the halothane/nitrous oxide anaesthetized rat. The SI nociceptive evoked potential (EP) amplitudes were dependent on the frequency of noxious heat stimulation. The amplitudes of SI potentials evoked by CO(2)-laser pulses (duration 15-20 ms, stimulation energy 21-28 mJ/mm(2)) delivered at a frequency of 0.1 Hz were approximately 40% of the amplitudes of potentials evoked by 1.0 Hz stimulation. After intrathecal lumbar application of either of the NMDA-antagonists CPP or MK-801, the amplitudes of nociceptive SI potentials, evoked by 1.0 Hz stimulation of the contralateral hindpaw, were reduced to approximately 40% of controls. By contrast, field potentials evoked by 0.1 Hz stimulation of the hindpaw were unaffected by MK-801. SI potentials evoked by 1.0 Hz stimulation of the contralateral forepaw did not change after lumbar application of CPP or MK-801, indicating that the depression of hindpaw EPs was due to a segmental effect in the spinal cord. It is concluded that spinal NMDA-receptor mechanisms amplify the acute transmission of nociceptive C fiber input to SI in a frequency-dependent way.

Increased BOLD Activation to Predator Stressor in Subiculum and Midbrain of Amphetamine-Sensitized Maternal Rats

PubMed Central

Febo, Marcelo; Pira, Ashley S.

2011-01-01

Amphetamine, which is known to cause sensitization, potentiates the hormonal and neurobiological signatures of stress and may also increase sensitivity to stress-inducing stimuli in limbic areas. Trimethylthiazoline (5 μL TMT) is a chemical constituent of fox feces that evokes innate fear and activates the neuronal and hormonal signatures of stress in rats. We used blood oxygen level dependent (BOLD) MRI to test whether amphetamine sensitization (1 mg/kg, i.p. X 3 days) in female rats has a lasting effect on the neural response to a stress-evoking stimulus, the scent of a predator, during the postpartum period. The subiculum and dopamine-enriched midbrain VTA/SN of amphetamine-sensitized, but not control mothers showed a greater BOLD signal response to predator odor than a control putrid scent. The greater responsiveness of these two brain regions following stimulant sensitization might impact neural processing in response to stressors in the maternal brain. PMID:21134359

Increased BOLD activation to predator stressor in subiculum and midbrain of amphetamine-sensitized maternal rats.

PubMed

Febo, Marcelo; Pira, Ashley S

2011-03-25

Amphetamine, which is known to cause sensitization, potentiates the hormonal and neurobiological signatures of stress and may also increase sensitivity to stress-inducing stimuli in limbic areas. Trimethylthiazoline (5μL TMT) is a chemical constituent of fox feces that evokes innate fear and activates the neuronal and hormonal signatures of stress in rats. We used blood oxygen level dependent (BOLD) MRI to test whether amphetamine sensitization (1mg/kg, i.p. ×3days) in female rats has a lasting effect on the neural response to a stress-evoking stimulus, the scent of a predator, during the postpartum period. The subiculum and dopamine-enriched midbrain VTA/SN of amphetamine-sensitized but not control mothers showed a greater BOLD signal response to predator odor than a control putrid scent. The greater responsiveness of these two brain regions following stimulant sensitization might impact neural processing in response to stressors in the maternal brain. Copyright © 2010 Elsevier B.V. All rights reserved.

The effect of different anesthetics on neurovascular coupling

PubMed Central

Franceschini, Maria Angela; Radhakrishnan, Harsha; Thakur, Kiran; Wu, Weicheng; Ruvinskaya, Svetlana; Carp, Stefan; Boas, David A.

2010-01-01

To date, the majority of neurovascular coupling studies focused on the thalamic afferents' activity in layer IV and the corresponding large spiking activity as responsible for functional hyperemia. This paper highlights the role of the secondary and late cortico-cortical transmission in neurovascular coupling. Simultaneous scalp electroencephalography (EEG) and diffuse optical imaging (DOI) measurements were obtained during multiple conditions of event-related electrical forepaw stimulation in 33 male Sprague-Dawley rats divided into 6 groups depending on the maintaining anesthetic - alpha-chloralose, pentobarbital, ketamine-xylazine, fentanyl-droperidol, isoflurane, or propofol. The somatosensory evoked potentials (SEP) were decomposed into four components and the question of which best predicts the hemodynamic responses was investigated. Results of the linear regression analysis show that the hemodynamic response is best correlated with the secondary and late cortico-cortical transmissions and not with the initial thalamic input activity in layer IV. Baseline cerebral blood flow (CBF) interacts with neural activity and influences the evoked hemodynamic responses. Finally, neurovascular coupling appears to be the same across all anesthetics used. PMID:20350606

Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): Are the measurements reliable?

PubMed

Wiggins, Ian M; Anderson, Carly A; Kitterick, Pádraig T; Hartley, Douglas E H

2016-09-01

Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Clinical Applications for EPs in the ICU.

PubMed

Koenig, Matthew A; Kaplan, Peter W

2015-12-01

In critically ill patients, evoked potential (EP) testing is an important tool for measuring neurologic function, signal transmission, and secondary processing of sensory information in real time. Evoked potential measures conduction along the peripheral and central sensory pathways with longer-latency potentials representing more complex thalamocortical and intracortical processing. In critically ill patients with limited neurologic exams, EP provides a window into brain function and the potential for recovery of consciousness. The most common EP modalities in clinical use in the intensive care unit include somatosensory evoked potentials, brainstem auditory EPs, and cortical event-related potentials. The primary indications for EP in critically ill patients are prognostication in anoxic-ischemic or traumatic coma, monitoring for neurologic improvement or decline, and confirmation of brain death. Somatosensory evoked potentials had become an important prognostic tool for coma recovery, especially in comatose survivors of cardiac arrest. In this population, the bilateral absence of cortical somatosensory evoked potentials has nearly 100% specificity for death or persistent vegetative state. Historically, EP has been regarded as a negative prognostic test, that is, the absence of cortical potentials is associated with poor outcomes while the presence cortical potentials are prognostically indeterminate. In recent studies, the presence of middle-latency and long-latency potentials as well as the amplitude of cortical potentials is more specific for good outcomes. Event-related potentials, particularly mismatch negativity of complex auditory patterns, is emerging as an important positive prognostic test in patients under comatose. Multimodality predictive algorithms that combine somatosensory evoked potentials, event-related potentials, and clinical and radiographic factors are gaining favor for coma prognostication.

Far-field brainstem responses evoked by vestibular and auditory stimuli exhibit increases in interpeak latency as brain temperature is decreased

NASA Technical Reports Server (NTRS)

Hoffman, L. F.; Horowitz, J. M.

1984-01-01

The effect of decreasing of brain temperature on the brainstem auditory evoked response (BAER) in rats was investigated. Voltage pulses, applied to a piezoelectric crystal attached to the skull, were used to evoke stimuli in the auditory system by means of bone-conducted vibrations. The responses were recorded at 37 C and 34 C brain temperatures. The peaks of the BAER recorded at 34 C were delayed in comparison with the peaks from the 37 C wave, and the later peaks were more delayed than the earlier peaks. These results indicate that an increase in the interpeak latency occurs as the brain temperature is decreased. Preliminary experiments, in which responses to brief angular acceleration were used to measure the brainstem vestibular evoked response (BVER), have also indicated increases in the interpeak latency in response to the lowering of brain temperature.

Maturation of the auditory system in clinically normal puppies as reflected by the brain stem auditory-evoked potential wave V latency-intensity curve and rarefaction-condensation differential potentials.

PubMed

Poncelet, L C; Coppens, A G; Meuris, S I; Deltenre, P F

2000-11-01

To evaluate auditory maturation in puppies. Ten clinically normal Beagle puppies. Puppies were examined repeatedly from days 11 to 36 after birth (8 measurements). Click-evoked brain stem auditory-evoked potentials (BAEP) were obtained in response to rarefaction and condensation click stimuli from 90 dB normal hearing level to wave V threshold, using steps of 10 dB. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation differential potential (RCDP). Steps of 5 dB were used to determine thresholds of RCDP and wave V. Slope of the low-intensity segment of the wave V latency-intensity curve was calculated. The intensity range at which RCDP could not be recorded (ie, pre-RCDP range) was calculated by subtracting the threshold of wave V from threshold of RCDP RESULTS: Slope of the wave V latency-intensity curve low-intensity segment evolved with age, changing from (mean +/- SD) -90.8 +/- 41.6 to -27.8 +/- 4.1 micros/dB. Similar results were obtained from days 23 through 36. The pre-RCDP range diminished as puppies became older, decreasing from 40.0 +/- 7.5 to 20.5 +/- 6.4 dB. Changes in slope of the latency-intensity curve with age suggest enlargement of the audible range of frequencies toward high frequencies up to the third week after birth. Decrease in the pre-RCDP range may indicate an increase of the audible range of frequencies toward low frequencies. Age-related reference values will assist clinicians in detecting hearing loss in puppies.

Guanfacine potentiates the activation of prefrontal cortex evoked by warning signals.

PubMed

Clerkin, Suzanne M; Schulz, Kurt P; Halperin, Jeffrey M; Newcorn, Jeffrey H; Ivanov, Iliyan; Tang, Cheuk Y; Fan, Jin

2009-08-15

Warning signals evoke an alert state of readiness that prepares for a rapid response by priming a thalamo-frontal-striatal network that includes the dorsolateral prefrontal cortex (DLPFC). Animal models indicate that noradrenergic input is essential for this stimulus-driven activation of DLPFC, but the precise mechanisms involved have not been determined. We tested the role that postsynaptic alpha(2A) adrenoceptors play in the activation of DLPFC evoked by warning cues using a placebo-controlled challenge with the alpha(2A) agonist guanfacine. Sixteen healthy young adults were scanned twice with event-related functional magnetic resonance imaging (fMRI), while performing a simple cued reaction time (RT) task following administration of a single dose of oral guanfacine (1 mg) and placebo in counterbalanced order. The RT task temporally segregates the neural effects of warning cues and motor responses and minimizes mnemonic demands. Warning cues produced a marked reduction in RT accompanied by significant activation in a distributed thalamo-frontal-striatal network, including bilateral DLPFC. Guanfacine selectively increased the cue-evoked activation of the left DLPFC and right anterior cerebellum, although this increase was not accompanied by further reductions in RT. The effects of guanfacine on DLPFC activation were specifically associated with the warning cue and were not seen for visual- or target-related activation. Guanfacine produced marked increases in the cue-evoked activation of DLPFC that correspond to the well-described actions of postsynaptic alpha(2) adrenoceptor stimulation. The current procedures provide an opportunity to test postsynaptic alpha(2A) adrenoceptor function in the prefrontal cortex in the pathophysiology of several psychiatric disorders.

Cyclopropyl glycine and proline-containing preparation noopept evoke two types of membrane potential responses in synaptoneurosomes.

PubMed

Lutsenko, V K; Vukolova, M N; Gudasheva, T A

2003-06-01

Proline, cyclo(Pro-Gly), and acyl-prolyl-containing dipeptide GVS-111 decreased synaptoneurosome membrane potential in a Ca2+-free medium. The efficiency of these preparations decreased in the following order: GVS>cyclo(Pro-Gly)>proline. Depolarization responses induced by endogenous nootropic agent cyclo(Pro-Gly) was dose-dependent and saturable; the threshold concentration of cyclo(Pro-Gly) was 10(-9) M. In a Ca2+-containing medium GVS and cyclo(Pro-Gly) induced both hyperpolarizing and depolarizing membrane responses of synaptoneurosomes. Possible mechanisms underlying changes in the membrane potential of synaptoneurosomes induced by nootropic agents are discussed. It was interesting whether modulation of electrogenesis can improve memory and potentiate the neuroprotective effect of the test nootropic agents.

Electrolyte and protein secretion by the perfused rabbit mandibular gland stimulated with acetylcholine or catecholamines

PubMed Central

Case, R. M.; Conigrave, A. D.; Novak, I.; Young, J. A.

1980-01-01

1. A method is described for the isolation and vascular perfusion in vitro of the mandibular gland of the rabbit. The perfusate is a physiological salt solution containing glucose as the only metabolic substrate. 2. During perfusion with solutions containing acetylcholine, the gland secretes vigorously at a rate and in a manner similar to that seen in vivo. Although the gland becomes oedematous during perfusion, the extent of this oedema appears to have no influence on secretory ability: the perfused glands were capable of functioning for at least 4 h, and often for more than 6 h. 3. Acetylcholine evoked a small secretory response at a concentration of 8 × 10-9 mol l-1 and a maximum response at 8 × 10-7 mol l-1. Eserine (2 × 10-5 mol l-1) evoked secretory responses comparable to those evoked by acetylcholine in a concentration of 8 × 10-9 mol l-1. Secretion, whether unstimulated or evoked by acetylcholine or eserine, could be blocked completely by atropine. 4. During prolonged stimulation with acetylcholine, the fluid secretory response declined rapidly over a period of about 15 min from an initial high value to a much lower plateau value. After 3 or more hours of stimulation, the secretory response began once more to decline, this time towards zero. If, before the second period of decline begins, stimulation is interrupted for about 30 min, the gland recovers its initial responsiveness to further stimulation with acetylcholine. 5. The Na, K, Cl and HCO3 concentrations and the osmolality of acetylcholine evoked saliva exhibited flow-dependency similar to that seen in vivo. The concentrations of Na and Cl, but not K and HCO3, increased by about 25 mmol l-1 during periods of prolonged stimulation with acetylcholine even though the salivary secretory rate was constant. The concentrations of K and HCO3, but not Na and Cl, increased progressively as the concentration of infused acetylcholine was increased. 6. Salivary protein secretion increased with increasing concentrations of acetylcholine to a greater extent than did fluid secretion. During continuous stimulation, the rate of protein secretion fell off much faster than the rate of fluid secretion. 7. The β-adrenergic agonist isoproterenol evoked a fluid secretory response only equal to about 5% of that evoked by acetylcholine, but still the response declined during continued stimulation. The electrolyte composition of isoproterenol-evoked saliva was vastly different from that evoked by acetylcholine, being particularly rich in K and HCO3. The isoproterenol-evoked saliva was also extremely rich in protein so that the total protein secretion evoked by isoproterenol was much greater than that evoked by acetylcholine. 8. The α-adrenergic agonist phenylephrine was without stimulatory effect on salivary fluid secretion and caused a reduction in the secretory response to acetylcholine. The drug had little or no effect on the electrolyte content of acetylcholine-evoked saliva and appeared to reduce its protein content. PMID:7381794

Gi proteins regulate adenylyl cyclase activity independent of receptor activation.

PubMed

Melsom, Caroline Bull; Ørstavik, Øivind; Osnes, Jan-Bjørn; Skomedal, Tor; Levy, Finn Olav; Krobert, Kurt Allen

2014-01-01

Despite the view that only β2- as opposed to β1-adrenoceptors (βARs) couple to G(i), some data indicate that the β1AR-evoked inotropic response is also influenced by the inhibition of Gi. Therefore, we wanted to determine if Gi exerts tonic receptor-independent inhibition upon basal adenylyl cyclase (AC) activity in cardiomyocytes. We used the Gs-selective (R,R)- and the Gs- and G(i)-activating (R,S)-fenoterol to selectively activate β2ARs (β1AR blockade present) in combination with Gi inactivation with pertussis toxin (PTX). We also determined the effect of PTX upon basal and forskolin-mediated responses. Contractility was measured ex vivo in left ventricular strips and cAMP accumulation was measured in isolated ventricular cardiomyocytes from adult Wistar rats. PTX amplified both the (R,R)- and (R,S)-fenoterol-evoked maximal inotropic response and concentration-dependent increases in cAMP accumulation. The EC50 values of fenoterol matched published binding affinities. The PTX enhancement of the Gs-selective (R,R)-fenoterol-mediated responses suggests that Gi regulates AC activity independent of receptor coupling to Gi protein. Consistent with this hypothesis, forskolin-evoked cAMP accumulation was increased and inotropic responses to forskolin were potentiated by PTX treatment. In non-PTX-treated tissue, phosphodiesterase (PDE) 3 and 4 inhibition or removal of either constitutive muscarinic receptor activation of Gi with atropine or removal of constitutive adenosine receptor activation with CGS 15943 had no effect upon contractility. However, in PTX-treated tissue, PDE3 and 4 inhibition alone increased basal levels of cAMP and accordingly evoked a large inotropic response. Together, these data indicate that Gi exerts intrinsic receptor-independent inhibitory activity upon AC. We propose that PTX treatment shifts the balance of intrinsic G(i) and Gs activity upon AC towards Gs, enhancing the effect of all cAMP-mediated inotropic agents.

Gi Proteins Regulate Adenylyl Cyclase Activity Independent of Receptor Activation

PubMed Central

Melsom, Caroline Bull; Ørstavik, Øivind; Osnes, Jan-Bjørn; Skomedal, Tor; Levy, Finn Olav; Krobert, Kurt Allen

2014-01-01

Background and purpose Despite the view that only β2- as opposed to β1-adrenoceptors (βARs) couple to Gi, some data indicate that the β1AR-evoked inotropic response is also influenced by the inhibition of Gi. Therefore, we wanted to determine if Gi exerts tonic receptor-independent inhibition upon basal adenylyl cyclase (AC) activity in cardiomyocytes. Experimental approach We used the Gs-selective (R,R)- and the Gs- and Gi-activating (R,S)-fenoterol to selectively activate β2ARs (β1AR blockade present) in combination with Gi inactivation with pertussis toxin (PTX). We also determined the effect of PTX upon basal and forskolin-mediated responses. Contractility was measured ex vivo in left ventricular strips and cAMP accumulation was measured in isolated ventricular cardiomyocytes from adult Wistar rats. Key results PTX amplified both the (R,R)- and (R,S)-fenoterol-evoked maximal inotropic response and concentration-dependent increases in cAMP accumulation. The EC50 values of fenoterol matched published binding affinities. The PTX enhancement of the Gs-selective (R,R)-fenoterol-mediated responses suggests that Gi regulates AC activity independent of receptor coupling to Gi protein. Consistent with this hypothesis, forskolin-evoked cAMP accumulation was increased and inotropic responses to forskolin were potentiated by PTX treatment. In non-PTX-treated tissue, phosphodiesterase (PDE) 3 and 4 inhibition or removal of either constitutive muscarinic receptor activation of Gi with atropine or removal of constitutive adenosine receptor activation with CGS 15943 had no effect upon contractility. However, in PTX-treated tissue, PDE3 and 4 inhibition alone increased basal levels of cAMP and accordingly evoked a large inotropic response. Conclusions and implications Together, these data indicate that Gi exerts intrinsic receptor-independent inhibitory activity upon AC. We propose that PTX treatment shifts the balance of intrinsic Gi and Gs activity upon AC towards Gs, enhancing the effect of all cAMP-mediated inotropic agents. PMID:25203113

LSD enhances the emotional response to music.

PubMed

Kaelen, M; Barrett, F S; Roseman, L; Lorenz, R; Family, N; Bolstridge, M; Curran, H V; Feilding, A; Nutt, D J; Carhart-Harris, R L

2015-10-01

There is renewed interest in the therapeutic potential of psychedelic drugs such as lysergic acid diethylamide (LSD). LSD was used extensively in the 1950s and 1960s as an adjunct in psychotherapy, reportedly enhancing emotionality. Music is an effective tool to evoke and study emotion and is considered an important element in psychedelic-assisted psychotherapy; however, the hypothesis that psychedelics enhance the emotional response to music has yet to be investigated in a modern placebo-controlled study. The present study sought to test the hypothesis that music-evoked emotions are enhanced under LSD. Ten healthy volunteers listened to five different tracks of instrumental music during each of two study days, a placebo day followed by an LSD day, separated by 5-7 days. Subjective ratings were completed after each music track and included a visual analogue scale (VAS) and the nine-item Geneva Emotional Music Scale (GEMS-9). Results demonstrated that the emotional response to music is enhanced by LSD, especially the emotions "wonder", "transcendence", "power" and "tenderness". These findings reinforce the long-held assumption that psychedelics enhance music-evoked emotion, and provide tentative and indirect support for the notion that this effect can be harnessed in the context of psychedelic-assisted psychotherapy. Further research is required to test this link directly.

Increased oscillatory theta activation evoked by violent digital game events.

PubMed

Salminen, Mikko; Ravaja, Niklas

2008-04-11

The authors examined electroencephalographic (EEG) oscillatory responses to two violent events, the player character wounding and killing an opponent character with a gun, in the digital game James Bond 007: NightFire. EEG was recorded from 25 (16 male) right-handed healthy young adults. EEG data were segmented into one 1-s baseline epoch before each event and two 1-s epochs after event onset. Power estimates (microV(2)) were derived with the fast Fourier transform (FFT) for each artefact free event. Both of the studied events evoked increased occipital theta (4-6Hz) responses as compared to the pre-event baseline. The wounding event evoked also increased occipital high theta (6-8Hz) response and the killing event evoked low alpha (8-10Hz) asymmetry over the central electrodes, both relative to the pre-event baseline. The results are discussed in light of facial electromyographic and electrodermal activity responses evoked by these same events, and it is suggested that the reported EEG responses may be attributable to affective processes related to these violent game events.

Central noradrenergic mechanisms and the acute stress response during painful stimulation.

PubMed

Chapman, C Richard; Bradshaw, David H; Donaldson, Gary W; Jacobson, Robert C; Nakamura, Yoshio

2014-12-01

Events that threaten tissue integrity including noxious stimulation activate central noradrenergic circuits, particularly locus coeruleus and its projections. Recent advances in theory hold that an adaptive, defensive shift in brain activity takes place in response to threat. In principle, this shift may accentuate the autonomic and central biomarkers of the perception of painful events and the experience of pain itself. We have examined the effects of an alpha-2 agonist on pupil dilation responses, skin conductance responses, near field somatosensory evoked potentials and pain reports in normal volunteers undergoing repeated trials of painful fingertip stimulation delivered at low, medium and high intensities. In a double-blinded study, 114 healthy male and female volunteers underwent repeated noxious stimulation under baseline, placebo and active drug conditions where the active drug was the alpha-2 agonist tizanidine 4 mg. In contrast to baseline and placebo conditions, tizanidine 4 mg significantly reduced the magnitudes of the mean pupil dilation response, the mean skin conductance response, the mean near field somatosensory evoked potential peak-to-peak amplitude and the mean pain intensity rating. Stimulus intensity significantly altered all three biomarkers and the pain report in a graded fashion. There were no sex differences. These findings support the hypotheses that painful events activate central noradrenergic circuits, and that these circuits play a role in the autonomic and central arousal associated with pain. © The Author(s) 2014.

Neural Entrainment in Drum Rhythms with Silent Breaks: Evidence from Steady-state Evoked and Event-related Potentials.

PubMed

Stupacher, Jan; Witte, Matthias; Hove, Michael J; Wood, Guilherme

2016-12-01

The fusion of rhythm, beat perception, and movement is often summarized under the term "entrainment" and becomes obvious when we effortlessly tap our feet or snap our fingers to the pulse of music. Entrainment to music involves a large network of brain structures, and neural oscillations at beat-related frequencies can help elucidate how this network is connected. Here, we used EEG to investigate steady-state evoked potentials (SSEPs) and event-related potentials (ERPs) during listening and tapping to drum clips with different rhythmic structures that were interrupted by silent breaks of 2-6 sec. This design allowed us to address the question of whether neural entrainment processes persist after the physical presence of musical rhythms and to link neural oscillations and event-related neural responses. During stimulus presentation, SSEPs were elicited in both tasks (listening and tapping). During silent breaks, SSEPs were only present in the tapping task. Notably, the amplitude of the N1 ERP component was more negative after longer silent breaks, and both N1 and SSEP results indicate that neural entrainment was increased when listening to drum rhythms compared with an isochronous metronome. Taken together, this suggests that neural entrainment to music is not solely driven by the physical input but involves endogenous timing processes. Our findings break ground for a tighter linkage between steady-state and transient evoked neural responses in rhythm processing. Beyond music perception, they further support the crucial role of entrained oscillatory activity in shaping sensory, motor, and cognitive processes in general.

Brain stem auditory potentials evoked by clicks in the presence of high-pass filtered noise in dogs.

PubMed

Poncelet, L; Deltenre, P; Coppens, A; Michaux, C; Coussart, E

2006-04-01

This study evaluates the effects of a high-frequency hearing loss simulated by the high-pass-noise masking method, on the click-evoked brain stem-evoked potentials (BAEP) characteristics in dogs. BAEP were obtained in response to rarefaction and condensation click stimuli from 60 dB normal hearing level (NHL, corresponding to 89 dB sound pressure level) to wave V threshold, using steps of 5 dB in eleven 58 to 80-day-old Beagle puppies. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation potential (RCDP). The procedure was repeated while constant level, high-pass filtered (HPF) noise was superposed to the click. Cut-off frequencies of the successively used filters were 8, 4, 2 and 1 kHz. For each condition, wave V and RCDP thresholds, and slope of the wave V latency-intensity curve (LIC) were collected. The intensity range at which RCDP could not be recorded (pre-RCDP range) was calculated. Compared with the no noise condition, the pre-RCDP range significantly diminished and the wave V threshold significantly increased when the superposed HPF noise reached the 4 kHz area. Wave V LIC slope became significantly steeper with the 2 kHz HPF noise. In this non-invasive model of high-frequency hearing loss, impaired hearing of frequencies from 8 kHz and above escaped detection through click BAEP study in dogs. Frequencies above 13 kHz were however not specifically addressed in this study.

Competition between calcium-activated K+ channels determines cholinergic action on firing properties of basolateral amygdala projection neurons.

PubMed

Power, John M; Sah, Pankaj

2008-03-19

Acetylcholine (ACh) is an important modulator of learning, memory, and synaptic plasticity in the basolateral amygdala (BLA) and other brain regions. Activation of muscarinic acetylcholine receptors (mAChRs) suppresses a variety of potassium currents, including sI(AHP), the calcium-activated potassium conductance primarily responsible for the slow afterhyperpolarization (AHP) that follows a train of action potentials. Muscarinic stimulation also produces inositol 1,4,5-trisphosphate (IP(3)), releasing calcium from intracellular stores. Here, we show using whole-cell patch-clamp recordings and high-speed fluorescence imaging that focal application of mAChR agonists evokes large rises in cytosolic calcium in the soma and proximal dendrites in rat BLA projection neurons that are often associated with activation of an outward current that hyperpolarizes the cell. This hyperpolarization results from activation of small conductance calcium-activated potassium (SK) channels, secondary to the release of calcium from intracellular stores. Unlike bath application of cholinergic agonists, which always suppressed the AHP, focal application of ACh often evoked a paradoxical enhancement of the AHP and spike-frequency adaptation. This enhancement was correlated with amplification of the action potential-evoked calcium response and resulted from the activation of SK channels. When SK channels were blocked, cholinergic stimulation always reduced the AHP and spike-frequency adaptation. Conversely, suppression of the sI(AHP) by the beta-adrenoreceptor agonist, isoprenaline, potentiated the cholinergic enhancement of the AHP. These results suggest that competition between cholinergic suppression of the sI(AHP) and cholinergic activation of the SK channels shapes the AHP and spike-frequency adaptation.

A translational study on looming-evoked defensive response and the underlying subcortical pathway in autism.

PubMed

Hu, Yu; Chen, Zhuoming; Huang, Lu; Xi, Yue; Li, Bingxiao; Wang, Hong; Yan, Jiajian; Lee, Tatia M C; Tao, Qian; So, Kwok-Fai; Ren, Chaoran

2017-11-07

Rapidly approaching objects indicating threats can induce defensive response through activating a subcortical pathway comprising superior colliculus (SC), lateral posterior nucleus (LP), and basolateral amygdala (BLA). Abnormal defensive response has been reported in autism, and impaired synaptic connections could be the underlying mechanism. Whether the SC-LP-BLA pathway processes looming stimuli abnormally in autism is not clear. Here, we found that looming-evoked defensive response is impaired in a subgroup of the valproic acid (VPA) mouse model of autism. By combining the conventional neurotracer and transneuronal rabies virus tracing techniques, we demonstrated that synaptic connections in the SC-LP-BLA pathway were abnormal in VPA mice whose looming-evoked defensive responses were absent. Importantly, we further translated the finding to children with autism and observed that they did not present looming-evoked defensive response. Furthermore, the findings of the DTI with the probabilistic tractography showed that the structural connections of SC-pulvinar-amygdala in autism children were weak. The pulvinar is parallel to the LP in a mouse. Because looming-evoked defensive response is innate in humans and emerges much earlier than do social and language functions, the absence of defensive response could be an earlier sign of autism in children.

Amplitude modulation of steady-state visual evoked potentials by event-related potentials in a working memory task

PubMed Central

Yao, Dezhong; Tang, Yu; Huang, Yilan; Su, Sheng

2009-01-01

Previous studies have shown that the amplitude and phase of the steady-state visual-evoked potential (SSVEP) can be influenced by a cognitive task, yet the mechanism of this influence has not been understood. As the event-related potential (ERP) is the direct neural electric response to a cognitive task, studying the relationship between the SSVEP and ERP would be meaningful in understanding this underlying mechanism. In this work, the traditional average method was applied to extract the ERP directly, following the stimulus of a working memory task, while a technique named steady-state probe topography was utilized to estimate the SSVEP under the simultaneous stimulus of an 8.3-Hz flicker and a working memory task; a comparison between the ERP and SSVEP was completed. The results show that the ERP can modulate the SSVEP amplitude, and for regions where both SSVEP and ERP are strong, the modulation depth is large. PMID:19960240

Central autonomic network mediates cardiovascular responses to acute inflammation: Relevance to increased cardiovascular risk in depression?

PubMed Central

Harrison, Neil A.; Cooper, Ella; Voon, Valerie; Miles, Ken; Critchley, Hugo D.

2013-01-01

Inflammation is a risk factor for both depression and cardiovascular disease. Depressed mood is also a cardiovascular risk factor. To date, research into mechanisms through which inflammation impacts cardiovascular health rarely takes into account central effects on autonomic cardiovascular control, instead emphasizing direct effects of peripheral inflammatory responses on endothelial reactivity and myocardial function. However, brain responses to inflammation engage neural systems for motivational and homeostatic control and are expressed through depressed mood state and changes in autonomic cardiovascular regulation. Here we combined an inflammatory challenge, known to evoke an acute reduction in mood, with neuroimaging to identify the functional brain substrates underlying potentially detrimental changes in autonomic cardiovascular control. We first demonstrated that alterations in the balance of low to high frequency (LF/HF) changes in heart rate variability (a measure of baroreflex sensitivity) could account for some of the inflammation-evoked changes in diastolic blood pressure, indicating a central (rather than solely local endothelial) origin. Accompanying alterations in regional brain metabolism (measured using 18FDG-PET) were analysed to localise central mechanisms of inflammation-induced changes in cardiovascular state: three discrete regions previously implicated in stressor-evoked blood pressure reactivity, the dorsal anterior and posterior cingulate and pons, strongly mediated the relationship between inflammation and blood pressure. Moreover, activity changes within each region predicted the inflammation-induced shift in LF/HF balance. These data are consistent with a centrally-driven component originating within brain areas supporting stressor evoked blood pressure reactivity. Together our findings highlight mechanisms binding psychological and physiological well-being and their perturbation by peripheral inflammation. PMID:23416033

The cortical spatiotemporal correlate of otolith stimulation: Vestibular evoked potentials by body translations.

PubMed

Ertl, M; Moser, M; Boegle, R; Conrad, J; Zu Eulenburg, P; Dieterich, M

2017-07-15

The vestibular organ senses linear and rotational acceleration of the head during active and passive motion. These signals are necessary for bipedal locomotion, navigation, the coordination of eye and head movements in 3D space. The temporal dynamics of vestibular processing in cortical structures have hardly been studied in humans, let alone with natural stimulation. The aim was to investigate the cortical vestibular network related to natural otolith stimulation using a hexapod motion platform. We conducted two experiments, 1. to estimate the sources of the vestibular evoked potentials (VestEPs) by means of distributed source localization (n=49), and 2. to reveal modulations of the VestEPs through the underlying acceleration intensity (n=24). For both experiments subjects were accelerated along the main axis (left/right, up/down, fore/aft) while the EEG was recorded. We were able to identify five VestEPs (P1, N1, P2, N2, P3) with latencies between 38 and 461 ms as well as an evoked beta-band response peaking with a latency of 68 ms in all subjects and for all acceleration directions. Source localization gave the cingulate sulcus visual (CSv) area and the opercular-insular region as the main origin of the evoked potentials. No lateralization effects due to handedness could be observed. In the second experiment, area CSv was shown to be integral in the processing of acceleration intensities as sensed by the otolith organs, hinting at its potential role in ego-motion detection. These robust VestEPs could be used to investigate the mechanisms of inter-regional interaction in the natural context of vestibular processing and multisensory integration. Copyright © 2017 Elsevier Inc. All rights reserved.

Degraded speech sound processing in a rat model of fragile X syndrome

PubMed Central

Engineer, Crystal T.; Centanni, Tracy M.; Im, Kwok W.; Rahebi, Kimiya C.; Buell, Elizabeth P.; Kilgard, Michael P.

2014-01-01

Fragile X syndrome is the most common inherited form of intellectual disability and the leading genetic cause of autism. Impaired phonological processing in fragile X syndrome interferes with the development of language skills. Although auditory cortex responses are known to be abnormal in fragile X syndrome, it is not clear how these differences impact speech sound processing. This study provides the first evidence that the cortical representation of speech sounds is impaired in Fmr1 knockout rats, despite normal speech discrimination behavior. Evoked potentials and spiking activity in response to speech sounds, noise burst trains, and tones were significantly degraded in primary auditory cortex, anterior auditory field and the ventral auditory field. Neurometric analysis of speech evoked activity using a pattern classifier confirmed that activity in these fields contains significantly less information about speech sound identity in Fmr1 knockout rats compared to control rats. Responses were normal in the posterior auditory field, which is associated with sound localization. The greatest impairment was observed in the ventral auditory field, which is related to emotional regulation. Dysfunction in the ventral auditory field may contribute to poor emotional regulation in fragile X syndrome and may help explain the observation that later auditory evoked responses are more disturbed in fragile X syndrome compared to earlier responses. Rodent models of fragile X syndrome are likely to prove useful for understanding the biological basis of fragile X syndrome and for testing candidate therapies. PMID:24713347

Synaptic vesicle pool‐specific modification of neurotransmitter release by intravesicular free radical generation

PubMed Central

Afuwape, Olusoji A. T.; Wasser, Catherine R.; Schikorski, Thomas

2016-01-01

Key points Synaptic transmission is mediated by the release of neurotransmitters from synaptic vesicles in response to stimulation or through the spontaneous fusion of a synaptic vesicle with the presynaptic plasma membrane.There is growing evidence that synaptic vesicles undergoing spontaneous fusion versus those fusing in response to stimuli are functionally distinct.In this study, we acutely probe the effects of intravesicular free radical generation on synaptic vesicles that fuse spontaneously or in response to stimuli.By targeting vesicles that preferentially release spontaneously, we can dissociate the effects of intravesicular free radical generation on spontaneous neurotransmission from evoked neurotransmission and vice versa.Taken together, these results further advance our knowledge of the synapse and the nature of the different synaptic vesicle pools mediating neurotransmission. Abstract Earlier studies suggest that spontaneous and evoked neurotransmitter release processes are maintained by synaptic vesicles which are segregated into functionally distinct pools. However, direct interrogation of the link between this putative synaptic vesicle pool heterogeneity and neurotransmission has been difficult. To examine this link, we tagged vesicles with horseradish peroxidase (HRP) – a haem‐containing plant enzyme – or antibodies against synaptotagmin‐1 (syt1). Filling recycling vesicles in hippocampal neurons with HRP and subsequent treatment with hydrogen peroxide (H2O2) modified the properties of neurotransmitter release depending on the route of HRP uptake. While strong depolarization‐induced uptake of HRP suppressed evoked release and augmented spontaneous release, HRP uptake during mild activity selectively impaired evoked release, whereas HRP uptake at rest solely potentiated spontaneous release. Expression of a luminal HRP‐tagged syt1 construct and subsequent H2O2 application resulted in a similar increase in spontaneous release and suppression as well as desynchronization of evoked release, recapitulating the canonical syt1 loss‐of‐function phenotype. An antibody targeting the luminal domain of syt1, on the other hand, showed that augmentation of spontaneous release and suppression of evoked release phenotypes are dissociable depending on whether the antibody uptake occurred at rest or during depolarization. Taken together, these findings indicate that vesicles that maintain spontaneous and evoked neurotransmitter release preserve their identity during recycling and syt1 function in suppression of spontaneous neurotransmission can be acutely dissociated from syt1 function to synchronize synaptic vesicle exocytosis upon stimulation. PMID:27723113

Use of the Stockwell Transform in the Detection of P300 Evoked Potentials with Low-Cost Brain Sensors.

PubMed

Pérez-Vidal, Alan F; Garcia-Beltran, Carlos D; Martínez-Sibaja, Albino; Posada-Gómez, Rubén

2018-05-09

The evoked potential is a neuronal activity that originates when a stimulus is presented. To achieve its detection, various techniques of brain signal processing can be used. One of the most studied evoked potentials is the P300 brain wave, which usually appears between 300 and 500 ms after the stimulus. Currently, the detection of P300 evoked potentials is of great importance due to its unique properties that allow the development of applications such as spellers, lie detectors, and diagnosis of psychiatric disorders. The present study was developed to demonstrate the usefulness of the Stockwell transform in the process of identifying P300 evoked potentials using a low-cost electroencephalography (EEG) device with only two brain sensors. The acquisition of signals was carried out using the Emotiv EPOC ® device—a wireless EEG headset. In the feature extraction, the Stockwell transform was used to obtain time-frequency information. The algorithms of linear discriminant analysis and a support vector machine were used in the classification process. The experiments were carried out with 10 participants; men with an average age of 25.3 years in good health. In general, a good performance (75⁻92%) was obtained in identifying P300 evoked potentials.

Visual and brainstem auditory evoked potentials in infants with severe vitamin B12 deficiency.

PubMed

Demir, Nihat; Koç, Ahmet; Abuhandan, Mahmut; Calik, Mustafa; Işcan, Akin

2015-01-01

Vitamin B12 plays an important role in the development of mental, motor, cognitive, and social functions via its role in DNA synthesis and nerve myelination. Its deficiency in infants might cause neuromotor retardation as well as megaloblastic anemia. The objective of this study was to investigate the effects of infantile vitamin B12 deficiency on evoked brain potentials and determine whether improvement could be obtained with vitamin B12 replacement at appropriate dosages. Thirty patients with vitamin B12 deficiency and 30 age-matched healthy controls were included in the study. Hematological parameters, visual evoked potentials, and brainstem auditory evoked potentials tests were performed prior to treatment, 1 week after treatment, and 3 months after treatment. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were found to be prolonged in 16 (53.3%) and 15 (50%) patients, respectively. Statistically significant improvements in VEP and BAEP examinations were determined 3 months after treatment. Three months after treatment, VEP and BAEP examinations returned to normal in 81.3% and 53.3% of subjects with prolonged VEPs and BAEPs, respectively. These results demonstrate that vitamin B12 deficiency in infants causes significant impairment in the auditory and visual functioning tests of the brain, such as VEP and BAEP.

Neurophysiological responses to unpleasant stimuli (acute electrical stimulations and emotional pictures) are increased in patients with schizophrenia

PubMed Central

Duval, Céline Z.; Goumon, Yannick; Kemmel, Véronique; Kornmeier, Jürgen; Dufour, André; Andlauer, Olivier; Vidailhet, Pierre; Poisbeau, Pierrick; Salvat, Eric; Muller, André; Mensah-Nyagan, Ayikoé G.; Schmidt-Mutter, Catherine; Giersch, Anne

2016-01-01

Patients with schizophrenia have often been described as insensitive to nociceptive signals, but objective evidence is sparse. We address this question by combining subjective behavioral and objective neurochemical and neurophysiological measures. The present study involved 21 stabilized and mildly symptomatic patients with schizophrenia and 21 control subjects. We applied electrical stimulations below the pain threshold and assessed sensations of pain and unpleasantness with rating scales, and Somatosensory Evoked Potentials (SEPs/EEG). We also measured attention, two neurochemical stress indices (ACTH/cortisol), and subjective VEPs/EEG responses to visual emotional stimuli. Our results revealed that, subjectively, patients’ evaluations do not differ from controls. However, the amplitude of EEG evoked potentials was greater in patients than controls as early as 50 ms after electrical stimulations and beyond one second after visual processing of emotional pictures. Such responses could not be linked to the stress induced by the stimulations, since stress hormone levels were stable. Nor was there a difference between patients and controls in respect of attention performance and tactile sensitivity. Taken together, all indices measured in patients in our study were either heightened or equivalent relative to healthy volunteers. PMID:26935652

Spatially Pooled Contrast Responses Predict Neural and Perceptual Similarity of Naturalistic Image Categories

PubMed Central

Groen, Iris I. A.; Ghebreab, Sennay; Lamme, Victor A. F.; Scholte, H. Steven

2012-01-01

The visual world is complex and continuously changing. Yet, our brain transforms patterns of light falling on our retina into a coherent percept within a few hundred milliseconds. Possibly, low-level neural responses already carry substantial information to facilitate rapid characterization of the visual input. Here, we computationally estimated low-level contrast responses to computer-generated naturalistic images, and tested whether spatial pooling of these responses could predict image similarity at the neural and behavioral level. Using EEG, we show that statistics derived from pooled responses explain a large amount of variance between single-image evoked potentials (ERPs) in individual subjects. Dissimilarity analysis on multi-electrode ERPs demonstrated that large differences between images in pooled response statistics are predictive of more dissimilar patterns of evoked activity, whereas images with little difference in statistics give rise to highly similar evoked activity patterns. In a separate behavioral experiment, images with large differences in statistics were judged as different categories, whereas images with little differences were confused. These findings suggest that statistics derived from low-level contrast responses can be extracted in early visual processing and can be relevant for rapid judgment of visual similarity. We compared our results with two other, well- known contrast statistics: Fourier power spectra and higher-order properties of contrast distributions (skewness and kurtosis). Interestingly, whereas these statistics allow for accurate image categorization, they do not predict ERP response patterns or behavioral categorization confusions. These converging computational, neural and behavioral results suggest that statistics of pooled contrast responses contain information that corresponds with perceived visual similarity in a rapid, low-level categorization task. PMID:23093921

Middle Latency Auditory Evoked Potential (MLAEP) in Workers with and without Tinnitus who are Exposed to Occupational Noise.

PubMed

dos Santos Filha, Valdete Alves Valentins; Samelli, Alessandra Giannella; Matas, Carla Gentile

2015-09-11

Tinnitus is an important occupational health concern, but few studies have focused on the central auditory pathways of workers with a history of occupational noise exposure. Thus, we analyzed the central auditory pathways of workers with a history of occupational noise exposure who had normal hearing threshold, and compared middle latency auditory evoked potential in those with and without noise-induced tinnitus. Sixty individuals (30 with and 30 without tinnitus) underwent the following procedures: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25-8 kHz, and middle latency auditory evoked potentials. Quantitative analysis of latencies and amplitudes of middle latency auditory evoked potential showed no significant differences between the groups with and without tinnitus. In the qualitative analysis, we found that both groups showed increased middle latency auditory evoked potential latencies. The study group had more alterations of the "both" type regarding the Na-Pa amplitude, while the control group had more "electrode effect" alterations, but these alterations were not significantly different when compared to controls. Individuals with normal hearing with or without tinnitus who are exposed to occupational noise have altered middle latency auditory evoked potential, suggesting impairment of the auditory pathways in cortical and subcortical regions. Although differences did not reach significance, individuals with tinnitus seemed to have more abnormalities in components of the middle latency auditory evoked potential when compared to individuals without tinnitus, suggesting alterations in the generation and transmission of neuroelectrical impulses along the auditory pathway.

Captured by the pain: pain steady-state evoked potentials are not modulated by selective spatial attention.

PubMed

Blöchl, Maria; Franz, Marcel; Miltner, Wolfgang H R; Weiss, Thomas

2015-04-07

Attention has been shown to affect the neural processing of pain. However, the exact mechanisms underlying this modulation remain unknown. Here, we used a new method called pain steady-state evoked potentials (PSSEPs) to investigate whether selective spatial attention affects EEG responses to tonic painful stimuli. In general, steady-state evoked potentials reflect changes in the EEG spectrum at a certain frequency that correspond to the frequency of a train of applied stimuli. In this study, high intensity transcutaneous electrical stimulation was delivered to both hands simultaneously with 31 Hz and 37 Hz, respectively. Subject׳s attention was directed to one of the two trains of stimulation in order to detect a small gap that was occasionally interspersed into the stimulus trains. Thereby, they had to ignore the stimulation applied to the other hand. Results show that PSSEPs were induced at 31 Hz and 37 Hz at frontal and central electrodes. PSSEPs occurred contralaterally to the respective hand stimulated with that frequency. Surprisingly, the magnitude of PSSEPs was not modulated by spatial attention towards one of the two stimuli. Our results indicate that attention can hardly be shifted between two simultaneously applied tonic painful stimulations. Copyright © 2015 Elsevier B.V. All rights reserved.

The P50 auditory evoked potential in violent and non-violent patients with schizophrenia.

PubMed

Fresán, Ana; Apiquian, Rogelio; García-Anaya, María; de la Fuente-Sandoval, Camilo; Nicolini, Humberto; Graff-Guerrero, Ariel

2007-12-01

Emotionally driven violence is facilitated by increased arousal. It may be a consequence of an information-processing deficit and the cognitive attributions for the stimuli given by the subject. The aim of this study was to compare the P50 evoked potential responses of violent patients with schizophrenia with non-violent patients with schizophrenia and healthy controls. Patients were classified into violent and non-violent in accordance to the Overt Aggression Scale. P50 auditory evoked potentials of 32 unmedicated patients with schizophrenia (violent=14, non-violent=18) and 17 healthy controls were recorded during five runs of 30 click pairs. Healthy controls exhibited a lower S2/S1 ratio when compared to violent (p<0.001) and non-violent (p=0.04) patients. Using a cutoff point of 0.50 for S2/S1 ratio to define abnormal gating a significant proportion of violent patients did not show P50 suppression (71.4%) in comparison to non-violent patients (38.9%) and healthy controls (23.5%) (p=0.02). Violent behavior in patients with schizophrenia could be associated with a disturbed information sensory gating. Violence in patients with schizophrenia may be facilitated by an increased arousal which may in turn be the result of an information-processing deficit.

New Perspectives on Assessing Amplification Effects

PubMed Central

Souza, Pamela E.; Tremblay, Kelly L.

2006-01-01

Clinicians have long been aware of the range of performance variability with hearing aids. Despite improvements in technology, there remain many instances of well-selected and appropriately fitted hearing aids whereby the user reports minimal improvement in speech understanding. This review presents a multistage framework for understanding how a hearing aid affects performance. Six stages are considered: (1) acoustic content of the signal, (2) modification of the signal by the hearing aid, (3) interaction between sound at the output of the hearing aid and the listener's ear, (4) integrity of the auditory system, (5) coding of available acoustic cues by the listener's auditory system, and (6) correct identification of the speech sound. Within this framework, this review describes methodology and research on 2 new assessment techniques: acoustic analysis of speech measured at the output of the hearing aid and auditory evoked potentials recorded while the listener wears hearing aids. Acoustic analysis topics include the relationship between conventional probe microphone tests and probe microphone measurements using speech, appropriate procedures for such tests, and assessment of signal-processing effects on speech acoustics and recognition. Auditory evoked potential topics include an overview of physiologic measures of speech processing and the effect of hearing loss and hearing aids on cortical auditory evoked potential measurements in response to speech. Finally, the clinical utility of these procedures is discussed. PMID:16959734

Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials.

PubMed

Nunez, Valerie; Shapley, Robert M; Gordon, James

2018-01-01

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component's power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics.

Auditory evoked potentials in the auditory system of a beluga whale Delphinapterus leucas to prolonged sound stimuli.

PubMed

Popov, Vladimir V; Sysueva, Evgenia V; Nechaev, Dmitry I; Rozhnov, Vyatcheslav V; Supin, Alexander Ya

2016-03-01

The effects of prolonged (up to 1500 s) sound stimuli (tone pip trains) on evoked potentials (the rate following response, RFR) were investigated in a beluga whale. The stimuli (rhythmic tone pips) were of frequencies of 45, 64, and 90 kHz at levels from 20 to 60 dB above threshold. Two experimental protocols were used: short- and long-duration. For the short-duration protocol, the stimuli were 500-ms-long pip trains that repeated at a rate of 0.4 trains/s. For the long-duration protocol, the stimuli were continuous pip successions lasting up to 1500 s. The RFR amplitude gradually decreased by three to seven times from 10 ms to 1500 s of stimulation. Decrease of response amplitude during stimulation was approximately proportional to initial (at the start of stimulation) response amplitude. Therefore, even for low stimulus level (down to 20 dB above the baseline threshold) the response was never suppressed completely. The RFR amplitude decay that occurred during stimulation could be satisfactorily approximated by a combination of two exponents with time constants of 30-80 ms and 3.1-17.6 s. The role of adaptation in the described effects and the impact of noise on the acoustic orientation of odontocetes are discussed.

Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials

PubMed Central

Shapley, Robert M.; Gordon, James

2018-01-01

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component’s power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics. PMID:29375753

Aroused with heart: Modulation of heartbeat evoked potential by arousal induction and its oscillatory correlates

PubMed Central

Luft, Caroline Di Bernardi; Bhattacharya, Joydeep

2015-01-01

Recent studies showed that the visceral information is constantly processed by the brain, thereby potentially influencing cognition. One index of such process is the heartbeat evoked potential (HEP), an ERP component related to the cortical processing of the heartbeat. The HEP is sensitive to a number of factors such as motivation, attention, pain, which are associated with higher levels of arousal. However, the role of arousal and its associated brain oscillations on the HEP has not been characterized, yet it could underlie the previous findings. Here we analysed the effects of high- (HA) and low-arousal (LA) induction on the HEP. Further, we investigated the brain oscillations and their role in the HEP in response to HA and LA inductions. As compared to LA, HA was associated with a higher HEP and lower alpha oscillations. Interestingly, individual differences in the HEP modulation by arousal induction were correlated with alpha oscillations. In particular, participants with higher alpha power during the arousal inductions showed a larger HEP in response to HA compared to LA. In summary, we demonstrated that arousal induction affects the cortical processing of heartbeats; and that the alpha oscillations may modulate this effect. PMID:26503014

Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

PubMed

Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng

2005-04-01

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Electrophysiological Evidence for the Sources of the Masking Level Difference.

PubMed

Fowler, Cynthia G

2017-08-16

The purpose of this review article is to review evidence from auditory evoked potential studies to describe the contributions of the auditory brainstem and cortex to the generation of the masking level difference (MLD). A literature review was performed, focusing on the auditory brainstem, middle, and late latency responses used in protocols similar to those used to generate the behavioral MLD. Temporal coding of the signals necessary for generating the MLD occurs in the auditory periphery and brainstem. Brainstem disorders up to wave III of the auditory brainstem response (ABR) can disrupt the MLD. The full MLD requires input to the generators of the auditory late latency potentials to produce all characteristics of the MLD; these characteristics include threshold differences for various binaural signal and noise conditions. Studies using central auditory lesions are beginning to identify the cortical effects on the MLD. The MLD requires auditory processing from the periphery to cortical areas. A healthy auditory periphery and brainstem codes temporal synchrony, which is essential for the ABR. Threshold differences require engaging cortical function beyond the primary auditory cortex. More studies using cortical lesions and evoked potentials or imaging should clarify the specific cortical areas involved in the MLD.

Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential

NASA Astrophysics Data System (ADS)

Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

2012-02-01

Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

Sustained signalling by PTH modulates IP3 accumulation and IP3 receptors through cyclic AMP junctions

PubMed Central

Meena, Abha; Tovey, Stephen C.; Taylor, Colin W.

2015-01-01

ABSTRACT Parathyroid hormone (PTH) stimulates adenylyl cyclase through type 1 PTH receptors (PTH1R) and potentiates the Ca2+ signals evoked by carbachol, which stimulates formation of inositol 1,4,5-trisphosphate (IP3). We confirmed that in HEK cells expressing PTH1R, acute stimulation with PTH(1-34) potentiated carbachol-evoked Ca2+ release. This was mediated by locally delivered cyclic AMP (cAMP), but unaffected by inhibition of protein kinase A (PKA), exchange proteins activated by cAMP, cAMP phosphodiesterases (PDEs) or substantial inhibition of adenylyl cyclase. Sustained stimulation with PTH(1-34) causes internalization of PTH1R–adenylyl cyclase signalling complexes, but the consequences for delivery of cAMP to IP3R within cAMP signalling junctions are unknown. Here, we show that sustained stimulation with PTH(1-34) or with PTH analogues that do not evoke receptor internalization reduced the potentiated Ca2+ signals and attenuated carbachol-evoked increases in cytosolic IP3. Similar results were obtained after sustained stimulation with NKH477 to directly activate adenylyl cyclase, or with the membrane-permeant analogue of cAMP, 8-Br-cAMP. These responses were independent of PKA and unaffected by substantial inhibition of adenylyl cyclase. During prolonged stimulation with PTH(1-34), hyperactive cAMP signalling junctions, within which cAMP is delivered directly and at saturating concentrations to its targets, mediate sensitization of IP3R and a more slowly developing inhibition of IP3 accumulation. PMID:25431134

Vestibular receptors contribute to cortical auditory evoked potentials.

PubMed

Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G

2014-03-01

Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Double ErrP Detection for Automatic Error Correction in an ERP-Based BCI Speller.

PubMed

Cruz, Aniana; Pires, Gabriel; Nunes, Urbano J

2018-01-01

Brain-computer interface (BCI) is a useful device for people with severe motor disabilities. However, due to its low speed and low reliability, BCI still has a very limited application in daily real-world tasks. This paper proposes a P300-based BCI speller combined with a double error-related potential (ErrP) detection to automatically correct erroneous decisions. This novel approach introduces a second error detection to infer whether wrong automatic correction also elicits a second ErrP. Thus, two single-trial responses, instead of one, contribute to the final selection, improving the reliability of error detection. Moreover, to increase error detection, the evoked potential detected as target by the P300 classifier is combined with the evoked error potential at a feature-level. Discriminable error and positive potentials (response to correct feedback) were clearly identified. The proposed approach was tested on nine healthy participants and one tetraplegic participant. The online average accuracy for the first and second ErrPs were 88.4% and 84.8%, respectively. With automatic correction, we achieved an improvement around 5% achieving 89.9% in spelling accuracy for an effective 2.92 symbols/min. The proposed approach revealed that double ErrP detection can improve the reliability and speed of BCI systems.

NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release.

PubMed

Hu, Zhitao; Vashlishan-Murray, Amy B; Kaplan, Joshua M

2015-01-21

A neuropeptide (NLP-12) and its receptor (CKR-2) potentiate tonic and evoked ACh release at Caenorhabditis elegans neuromuscular junctions. Increased evoked release is mediated by a presynaptic pathway (egl-30 Gαq and egl-8 PLCβ) that produces DAG, and by DAG binding to short and long UNC-13 proteins. Potentiation of tonic ACh release persists in mutants deficient for egl-30 Gαq and egl-8 PLCβ and requires DAG binding to UNC-13L (but not UNC-13S). Thus, NLP-12 adjusts tonic and evoked release by distinct mechanisms. Copyright © 2015 the authors 0270-6474/15/351038-05$15.00/0.

Role of the autonomic nervous system and baroreflex in stress-evoked cardiovascular responses in rats.

PubMed

Dos Reis, Daniel Gustavo; Fortaleza, Eduardo Albino Trindade; Tavares, Rodrigo Fiacadori; Corrêa, Fernando Morgan Aguiar

2014-07-01

Restraint stress (RS) is an experimental model to study stress-related cardiovascular responses, characterized by sustained pressor and tachycardiac responses. We used pharmacologic and surgical procedures to investigate the role played by sympathetic nervous system (SNS) and parasympathetic nervous system (PSNS) in the mediation of stress-evoked cardiovascular responses. Ganglionic blockade with pentolinium significantly reduced RS-evoked pressor and tachycardiac responses. Intravenous treatment with homatropine methyl bromide did not affect the pressor response but increased tachycardia. Pretreatment with prazosin reduced the pressor and increased the tachycardiac response. Pretreatment with atenolol did not affect the pressor response but reduced tachycardia. The combined treatment with atenolol and prazosin reduced both pressor and tachycardiac responses. Adrenal demedullation reduced the pressor response without affecting tachycardia. Sinoaortic denervation increased pressor and tachycardiac responses. The results indicate that: (1) the RS-evoked cardiovascular response is mediated by the autonomic nervous system without an important involvement of humoral factors; (2) hypertension results primarily from sympathovascular and sympathoadrenal activation, without a significant involvement of the cardiac sympathetic component (CSNS); (3) the abrupt initial peak in the hypertensive response to restraint is sympathovascular-mediated, whereas the less intense but sustained hypertensive response observed throughout the remaining restraint session is mainly mediated by sympathoadrenal activation and epinephrine release; (4) tachycardia results from CSNS activation, and not from PSNS inhibition; (5) RS evokes simultaneous CSNS and PSNS activation, and heart rate changes are a vector of both influences; (6) the baroreflex is functional during restraint, and modulates both the vascular and cardiac responses to restraint.

Development of visual evoked potentials in neonates. A study using light emitting diode goggles.

PubMed Central

Chin, K C; Taylor, M J; Menzies, R; Whyte, H

1985-01-01

We used a signal averager with light emitting diode goggles as the photostimulator to study the development of the visual evoked potentials in 40 normal neonates of between 23 and 42 weeks' gestation. All except two infants of less than 24 weeks' gestation had replicable visual evoked potentials. A negative peak of latency (mean (SD), 308 (21) msec) was present in all infants, but the development of the primary positive peak depended on maturity. Only infants of 37 weeks or more had a consistent positive peak of latency (mean (SD), 220 (22) msec). The practical simplicity and reliability of this technique has distinct advantages over previous conventional recording systems. Neonatal visual evoked potentials are shown to change with maturity. PMID:4091582

Auditory evoked responses to binaural beat illusion: stimulus generation and the derivation of the Binaural Interaction Component (BIC).

PubMed

Ozdamar, Ozcan; Bohorquez, Jorge; Mihajloski, Todor; Yavuz, Erdem; Lachowska, Magdalena

2011-01-01

Electrophysiological indices of auditory binaural beats illusions are studied using late latency evoked responses. Binaural beats are generated by continuous monaural FM tones with slightly different ascending and descending frequencies lasting about 25 ms presented at 1 sec intervals. Frequency changes are carefully adjusted to avoid any creation of abrupt waveform changes. Binaural Interaction Component (BIC) analysis is used to separate the neural responses due to binaural involvement. The results show that the transient auditory evoked responses can be obtained from the auditory illusion of binaural beats.

The Time Course of Segmentation and Cue-Selectivity in the Human Visual Cortex

PubMed Central

Appelbaum, Lawrence G.; Ales, Justin M.; Norcia, Anthony M.

2012-01-01

Texture discontinuities are a fundamental cue by which the visual system segments objects from their background. The neural mechanisms supporting texture-based segmentation are therefore critical to visual perception and cognition. In the present experiment we employ an EEG source-imaging approach in order to study the time course of texture-based segmentation in the human brain. Visual Evoked Potentials were recorded to four types of stimuli in which periodic temporal modulation of a central 3° figure region could either support figure-ground segmentation, or have identical local texture modulations but not produce changes in global image segmentation. The image discontinuities were defined either by orientation or phase differences across image regions. Evoked responses to these four stimuli were analyzed both at the scalp and on the cortical surface in retinotopic and functional regions-of-interest (ROIs) defined separately using fMRI on a subject-by-subject basis. Texture segmentation (tsVEP: segmenting versus non-segmenting) and cue-specific (csVEP: orientation versus phase) responses exhibited distinctive patterns of activity. Alternations between uniform and segmented images produced highly asymmetric responses that were larger after transitions from the uniform to the segmented state. Texture modulations that signaled the appearance of a figure evoked a pattern of increased activity starting at ∼143 ms that was larger in V1 and LOC ROIs, relative to identical modulations that didn't signal figure-ground segmentation. This segmentation-related activity occurred after an initial response phase that did not depend on the global segmentation structure of the image. The two cue types evoked similar tsVEPs up to 230 ms when they differed in the V4 and LOC ROIs. The evolution of the response proceeded largely in the feed-forward direction, with only weak evidence for feedback-related activity. PMID:22479566

Effects of receptor-selective neurokinin agonists and a neurokinin antagonist on the electrical activity of spinal cord neurones in culture.

PubMed

Wienrich, M; Reuss, K; Harting, J

1989-11-01

1. Rat spinal cord neurones grown in tissue culture were used to examine the electrophysiological effects of the neurokin in (NK)-selective agonists (pGlu6, Pro9) substance P(6-11) (septide; NK1, 10(-6)M) and (pGlu5, MePhe8, MeGly9)SP(1-7) (DiMe-C7; NK3, 10(-6)M). In addition, the effect of the neurokinin antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)SP (10(-5)M) on the neurokinin-evoked responses was investigated. 2. Neurokinin-evoked responses consisted of an increase in neuronal activity with or without long-lasting (mean: 50s) depolarizations of the membrane potential of up to 25mV. The latter also occurred in the presence of tetrodotoxin (10(-7)M) (direct response). 3. In a number of spinal cord neurones (n = 17) only septide induced a membrane depolarization while DiMe-C7 elicited no response. On the other hand, in 2 neurones a response was exclusively evoked by DiMe-C7. 4. The neurokinin antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)SP had no effect of its own but blocked the septide- and DiMe-C7-induced depolarizations. It had no effect on the glutamate (10(-5)M)-evoked depolarization. 5. It is concluded that by the use of neurokinin receptor-selective agonists, subpopulations of spinal cord neurones in primary dissociated cell culture can be differentiated which express the NK1 or the NK3 receptor. Cells expressing only the NK1 receptor outnumber those expressing only the NK3 receptor subtype. Both receptors can be blocked by the neurokinin antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)SP.

Speech-evoked Brainstem Auditory Responses and Auditory Processing Skills: A Correlation in Adults with Hearing Loss

PubMed Central

Sanguebuche, Taissane Rodrigues; Peixe, Bruna Pias; Bruno, Rúbia Soares; Biaggio, Eliara Pinto Vieira; Garcia, Michele Vargas

2018-01-01

Introduction  The auditory system consists of sensory structures and central connections. The evaluation of the auditory pathway at a central level can be performed through behavioral and electrophysiological tests, because they are complementary to each other and provide important information about comprehension. Objective  To correlate the findings of speech brainstem-evoked response audiometry with the behavioral tests Random Gap Detection Test and Masking Level Difference in adults with hearing loss. Methods  All patients were submitted to a basic audiological evaluation, to the aforementioned behavioral tests, and to an electrophysiological assessment, by means of click-evoked and speech-evoked brainstem response audiometry. Results  There were no statistically significant values among the electrophysiological test and the behavioral tests. However, there was a significant correlation between the V and A waves, as well as the D and F waves, of the speech-evoked brainstem response audiometry peaks. Such correlations are positive, indicating that the increase of a variable implies an increase in another and vice versa. Conclusion  It was possible to correlate the findings of the speech-evoked brainstem response audiometry with those of the behavioral tests Random Gap Detection and Masking Level Difference. However, there was no statistically significant correlation between them. This shows that the electrophysiological evaluation does not depend uniquely on the behavioral skills of temporal resolution and selective attention. PMID:29379574

Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study.

PubMed

Kumru, H; Kofler, M; Flores, M C; Portell, E; Robles, V; Leon, N; Vidal, J

2013-08-01

Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment. Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group. In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time. Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen. © 2012 European Federation of International Association for the Study of Pain Chapters.

The Effect of Increased Intracranial Pressure on Vestibular Evoked Myogenic Potentials in Superior Canal Dehiscence Syndrome

PubMed Central

Janky, Kristen L.; Zuniga, M. Geraldine; Schubert, Michael C; Carey, John P

2014-01-01

Objective To determine if vestibular evoked myogenic potential (VEMP) responses change during inversion in patients with superior canal dehiscence syndrome (SCDS) compared to controls. Methods Sixteen subjects with SCDS (mean: 43, range 30–57 years) and 15 age-matched, healthy subjects (mean: 41, range 22–57 years) completed cervical VEMP (cVEMP) in response to air conduction click stimuli and ocular VEMP (oVEMP) in response to air conduction 500 Hz tone burst stimuli and midline tap stimulation. All VEMP testing was completed in semi-recumbent and inverted conditions. Results SCDS ears demonstrated significantly larger oVEMP peak-to-peak amplitudes in comparison to normal ears in semi-recumbency. While corrected cVEMP peak-to-peak amplitudes were larger in SCDS ears; this did not reach significance in our sample. Overall, there was not a differential change in o- or cVEMP amplitude with inversion between SCDS and normal subjects. Conclusions Postural-induced changes in o- and cVEMP responses were measured in the steady state regardless of whether the labyrinth was intact or dehiscent. Significance VEMP responses are blunted during inversion. Although steady-state measurements of VEMPs during inversion do not increase diagnostic accuracy for SCDS, the findings suggest that inversion may provide more general insights into the equilibration of pressures between intracranial and intralabyrinthine fluids. PMID:25103787

Ipsilesional motor-evoked potential absence in pediatric hemiparesis impacts tracking accuracy of the less affected hand.

PubMed

Cassidy, Jessica M; Carey, James R; Lu, Chiahao; Krach, Linda E; Feyma, Tim; Durfee, William K; Gillick, Bernadette T

2015-12-01

This study analyzed the relationship between electrophysiological responses to transcranial magnetic stimulation (TMS), finger tracking accuracy, and volume of neural substrate in children with congenital hemiparesis. Nineteen participants demonstrating an ipsilesional motor-evoked potential (MEP) were compared with eleven participants showing an absent ipsilesional MEP response. Comparisons of finger tracking accuracy from the affected and less affected hands and ipsilesional/contralesional (I/C) volume ratio for the primary motor cortex (M1) and posterior limb of internal capsule (PLIC) were done using two-sample t-tests. Participants showing an ipsilesional MEP response demonstrated superior tracking performance from the less affected hand (p=0.016) and significantly higher I/C volume ratios for M1 (p=0.028) and PLIC (p=0.005) compared to participants without an ipsilesional MEP response. Group differences in finger tracking accuracy from the affected hand were not significant. These results highlight differentiating factors amongst children with congenital hemiparesis showing contrasting MEP responses: less affected hand performance and preserved M1 and PLIC volume. Along with MEP status, these factors pose important clinical implications in pediatric stroke rehabilitation. These findings may also reflect competitive developmental processes associated with the preservation of affected hand function at the expense of some function in the less affected hand. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effects of L-glutamate, AMPA, quisqualate, and kainate on retinal horizontal cells depend on adaptational state: implications for rod-cone interactions.

PubMed

Krizaj, D; Akopian, A; Witkovsky, P

1994-09-01

We studied the responses of isolated and intact luminosity-type horizontal cells (L-HC) in the Xenopus retina to L-glutamate (L-glu) and its analogs. Isolated L-HCs studied with whole-cell patch clamp responded to L-glu, kainate (KA), AMPA, or quisqualate (quis) with inward currents from a holding potential of -60 mV, associated with a conductance increase. The current elicited by KA was relatively large and sustained, whereas AMPA or quis evoked a desensitizing current. Coapplication of quis and KA resulted in a smaller current and conductance change than that evoked by a pulse of either alone at the same concentration. This finding suggests that the L-HC has a single subtype of glutamate receptor that responds to both quis and KA. Prior exposure to dopamine enhanced the KA-evoked current about twofold. In the superfused eyecup we found that L-HC responses to quinoxalinediones (CNQX or DNQX) and to L-glu, KA, AMPA, and quis varied as a function of adaptational state. When driven exclusively by either cones or by rods, CNQX/DNQX hyperpolarized the L-HC and reduced its light response, without altering response kinetics, indicating that both rods and cones communicate with L-HCs at ionotropic glutamatergic synapses. Under mesopic conditions, however, as CNQX or DNQX reduced cone input, the rod input to the L-HC increased up to fivefold in magnitude and had slowed kinetics. The depolarizing response of the L-HC to L-glu, AMPA, or quis was relatively small and transient under photopic conditions, but was much larger and sustained when the eyecup was dark adapted. The D1 dopamine antagonist SCH 23390 potentiated the response to quis. In contrast, responses to KA were largest in light-adapted eyecups, were potentiated by a D1 dopamine agonist, SKF 38393, and were reduced by SCH 23390. We hypothesize that the segregated populations of glutamate receptors in the L-HC opposite cone and rod synaptic endings can be separately modulated to respond differentially to the native transmitter, glutamate. In photopic and mesopic states the dominant cone input tonically inhibits rod to L-HC communication. This inhibition appears to occur at the postsynaptic membrane and may be mediated by second messengers.

Cortical Response Variability as a Developmental Index of Selective Auditory Attention

ERIC Educational Resources Information Center

Strait, Dana L.; Slater, Jessica; Abecassis, Victor; Kraus, Nina

2014-01-01

Attention induces synchronicity in neuronal firing for the encoding of a given stimulus at the exclusion of others. Recently, we reported decreased variability in scalp-recorded cortical evoked potentials to attended compared with ignored speech in adults. Here we aimed to determine the developmental time course for this neural index of auditory…

Comparative Analytical Study of Evoked and Event Related Potentials as Correlates of Cognitive Processes

DTIC Science & Technology

1990-07-16

lower brain levels, probably precognitive , suggesting the need to distinguish the components in humans that depend on cognition from those that do...definition of the stimulus regime and that much of this response occurs at lower brain levels, probably precognitive , suggesting the need to distinguish the

Asymmetrical Cortical Processing of Radial Expansioncontraction in Infants and Adults

ERIC Educational Resources Information Center

Shirai, Nobu; Birtles, Deirdre; Wattam-Bell, John; Yamaguchi, Masami K.; Kanazawa, So; Atkinson, Janette; Braddick, Oliver

2009-01-01

We report asymmetrical cortical responses (steady-state visual evoked potentials) to radial expansion and contraction in human infants and adults. Forty-four infants (22 3-month-olds and 22 4-month-olds) and nine adults viewed dynamic dot patterns which cyclically (2.1 Hz) alternate between radial expansion (or contraction) and random directional…

The Farther Reaches of Gestalt Therapy: A Conversation with George Brown

ERIC Educational Resources Information Center

Carter, Betsie; Vargiu, Susan

1977-01-01

This interview evokes much of the essential spirit of Gestalt Therapy and some of its techniques. Gestalt is a method of growth for developing the potential of the healthy individual. It emphasizes acquiring awareness of the existential moment, integrating unconscious aspects of self, and taking responsibility for one's actions. (Author/BP)

Electrophysiological Evidence for the Sources of the Masking Level Difference

ERIC Educational Resources Information Center

Fowler, Cynthia G.

2017-01-01

Purpose: The purpose of this review article is to review evidence from auditory evoked potential studies to describe the contributions of the auditory brainstem and cortex to the generation of the masking level difference (MLD). Method: A literature review was performed, focusing on the auditory brainstem, middle, and late latency responses used…

A test of the embodied simulation theory of object perception: potentiation of responses to artifacts and animals.

PubMed

Matheson, Heath E; White, Nicole C; McMullen, Patricia A

2014-07-01

Theories of embodied object representation predict a tight association between sensorimotor processes and visual processing of manipulable objects. Previous research has shown that object handles can 'potentiate' a manual response (i.e., button press) to a congruent location. This potentiation effect is taken as evidence that objects automatically evoke sensorimotor simulations in response to the visual presentation of manipulable objects. In the present series of experiments, we investigated a critical prediction of the theory of embodied object representations that potentiation effects should be observed with manipulable artifacts but not non-manipulable animals. In four experiments we show that (a) potentiation effects are observed with animals and artifacts; (b) potentiation effects depend on the absolute size of the objects and (c) task context influences the presence/absence of potentiation effects. We conclude that potentiation effects do not provide evidence for embodied object representations, but are suggestive of a more general stimulus-response compatibility effect that may depend on the distribution of attention to different object features.

Temporal and spatial temperature distribution in the glabrous skin of rats induced by short-pulse CO2 laser

NASA Astrophysics Data System (ADS)

Lu, Pen-Li; Hsu, Shu-Shen; Tsai, Meng-Li; Jaw, Fu-Shan; Wang, An-Bang; Yen, Chen-Tung

2012-11-01

Pain is a natural alarm that aids the body in avoiding potential danger and can also present as an important indicator in clinics. Infrared laser-evoked potentials can be used as an objective index to evaluate nociception. In animal studies, a short-pulse laser is crucial because it completes the stimulation before escape behavior. The objective of the present study was to obtain the temporal and spatial temperature distributions in the skin caused by the irradiation of a short-pulse laser. A fast speed infrared camera was used to measure the surface temperature caused by a CO2 laser of different durations (25 and 35 ms) and power. The measured results were subsequently implemented with a three-layer finite element model to predict the subsurface temperature. We found that stratum corneum was crucial in the modeling of fast temperature response, and escape behaviors correlated with predictions of temperature at subsurface. Results indicated that the onset latency and duration of activated nociceptors must be carefully considered when interpreting physiological responses evoked by infrared irradiation.

Long-term moderate exercise accelerates the recovery of stress-evoked cardiovascular responses.

PubMed

Hsu, Yuan-Chang; Tsai, Sheng-Feng; Yu, Lung; Chuang, Jih-Ing; Wu, Fong-Sen; Jen, Chauying J; Kuo, Yu-Min

2016-01-01

Psychological stress is an important global health problem. It is well documented that stress increases the incidences of various cardiovascular disorders. Regular exercise is known to reduce resting blood pressure (BP) and heart rate (HR). This study was designed to clarify the effects of long-term exercise on stress-evoked cardiovascular responses and to emphasize post-stress recovery effects. Male Wistar rats underwent 8 weeks of moderate treadmill training, with cardiovascular responses, autonomic nervous system activities and local Fos reactivity changes in the cardiovascular regulation center were monitored before, during and after immobilization stress. A spectral analysis of cardiovascular parameters was used to examine autonomic nervous activities. We found that long-term exercise (i) lowered resting BP, HR and sympathetic activity, but increased resting parasympathetic activity and baroreflex sensitivity (BRS); (ii) accelerated post-stress recovery of stress-evoked cardiovascular and sympathetic responses along with increased BRS and (iii) accelerated post-stress recovery of stress-evoked neuron activations in the paraventricular nucleus, but delayed it in the nucleus of the tractus solitarius. We conclude that, in rats, long-term exercise accelerated recovery of stress-evoked cardiovascular responses differentially altering hypothalamic and medullar neuron activities.

Wavelet analysis can sensitively describe dynamics of ethanol evoked local field potentials of the slug (Limax marginatus) brain.

PubMed

Schütt, Atsuko; Ito, Iori; Rosso, Osvaldo A; Figliola, Alejandra

2003-10-30

Odorants evoke characteristic, but complex, local field potentials (LFPs) in the molluscan brain. Wavelet tools in combination with Fourier analysis can detect and characterize hitherto unknown discrete, slow potentials underlying the conspicuous oscillations. Ethanol was one of the odorants that we have extensively studied (J. Neurosci. Methods, 119 (2002) 89). To detect new features and to elucidate their functions, we tested the wavelet tools on the ethanol-evoked LFP responses of the slug (Limax) procerebrum. Recordings were made in vitro from the neuropile and the cell layer. The present study led to the following findings: (i) Mutual exclusion. Energy concentrated mainly in two ranges, (a) 0.1-0.4 Hz and (b) 1.56-12.5 Hz, and the sum of energy remained constant throughout experiments regardless of the condition. A redistribution of relative energy within this sum seemed to occur in the course of main, possible interactions between the two components excluding each other ('mutual exclusion'). (ii) Transient signal ordering and disordering. Ethanol stimulation alternatingly evoked periods of strongly time evolving oscillation dominated by the energy of 1.56-12.5 Hz (increase of entropy=disordered or complexly ordered state) and those of near-silence were predominated by the energy of 0.1-0.4 Hz (decrease of entropy=ordered state). (iii) About 0.1 Hz slow wave oscillation. It was robust. The dominant energy oscillation and the resulting large entropy fluctuation were negatively correlated to each other, and revealed strong frequency-tuning or synchronization at this frequency. Our findings suggest that discrete slow waves play functionally important roles in the invertebrate brain, as widely known in vertebrate EEG. Wavelet tools allow an easy interpretation of several minutes of frequency variations in a single display and give precise information on stimulus-evoked complex change of the neural system describing the new state 'more ordered' or 'non-ordered or more complexly ordered'.

Enhanced 5-hydroxytryptamine (5-HT) release from vascular adrenergic nerves in spontaneously hypertensive rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawasaki, H.; Urabe, M.; Takasaki, K.

1986-03-01

The release of 5-HT from vascular adrenergic nerves was compared between normotensive Wistar Kyoto rats (WKY) and SHR. The mesenteric vascular bed isolated from WKY and SHR was perfused with Krebs solution at a constant flow rate of 5 ml/min. Periarterial nerve stimulation (PNS) was delivered at 4 to 16 Hz for 30 sec. In the SHR preparation, the pressor response to PNS, previously decreased by prazonsin (50 nM), was greatly potentiated after treatment with 5-HT(1 ..mu..M) for 15 min and a frequency-dependent pressor response to PNS reappeared, whereas the 5-HT treatment did not alter the pressor response to exogenousmore » norepinephrine (1 nmol) previously reduced by prazonsin. The potentiation of pressor response to PNS after 5-HT treatment was small in the WKY preparation. This potentiation in both WKY and SHR did not occur in the presence of ketanserin (10 nM). In the preparation labeled with (/sup 3/H)-5-HT, PNS (4-16 Hz) evoked a frequency-dependent increase of (/sup 3/H)-efflux, which was abolished by treatment with tetrodotoxin (100 nM) or 6-hydroxydopamine (50 mg/kg i.p. x 2) and in calcium-free Krebs solution. The PNS evoked-(/sup 3/H)-efflux was much greater in SHR than WKY. These results suggest that the release of 5-HT from vascular adrenergic nerves by PNS is enhanced in the SHR preparation.« less

Evaluating interhemispheric cortical responses to transcranial magnetic stimulation in chronic stroke: A TMS-EEG investigation.

PubMed

Borich, Michael R; Wheaton, Lewis A; Brodie, Sonia M; Lakhani, Bimal; Boyd, Lara A

2016-04-08

TMS-evoked cortical responses can be measured using simultaneous electroencephalography (TMS-EEG) to directly quantify cortical connectivity in the human brain. The purpose of this study was to evaluate interhemispheric cortical connectivity between the primary motor cortices (M1s) in participants with chronic stroke and controls using TMS-EEG. Ten participants with chronic stroke and four controls were tested. TMS-evoked responses were recorded at rest and during a typical TMS assessment of transcallosal inhibition (TCI). EEG recordings from peri-central gyral electrodes (C3 and C4) were evaluated using imaginary phase coherence (IPC) analyses to quantify levels of effective interhemispheric connectivity. Significantly increased TMS-evoked beta (15-30Hz frequency range) IPC was observed in the stroke group during ipsilesional M1 stimulation compared to controls during TCI assessment but not at rest. TMS-evoked beta IPC values were associated with TMS measures of transcallosal inhibition across groups. These results suggest TMS-evoked EEG responses can index abnormal effective interhemispheric connectivity in chronic stroke. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Sex differences in the neural representation of pain unpleasantness.

PubMed

Girard-Tremblay, Lydia; Auclair, Vincent; Daigle, Kathya; Léonard, Guillaume; Whittingstall, Kevin; Goffaux, Philippe

2014-08-01

Sex differences in pain perception are still poorly understood, but they may be related to the way the brains of men and women respond to the affective dimensions of pain. Using a matched pain intensity paradigm, where pain intensity was kept constant across participants but pain unpleasantness was left free to vary among participants, we studied the relationship between pain unpleasantness and pain-evoked brain activity in healthy men and women separately. Experimental pain was provoked using transcutaneous electrical stimulation of the sural nerve while pain-related brain activity was measured using somatosensory-evoked brain potentials with source localization. Cardiac responses to pain were also measured using electrocardiac recordings. Results revealed that subjective pain unpleasantness was strongly associated with increased perigenual anterior cingulate cortex activity in women, whereas it was strongly associated with decreased ventromedial prefrontal cortex activity in men. Only ventromedial prefrontal cortex deactivations in men were additionally associated with increased autonomic cardiac arousal. These results suggest that in order to deal with pain's objectionable properties, men preferentially deactivate prefrontal suppression regions, leading to the mobilization of threat-control circuits, whereas women recruit well-known emotion-processing areas of the brain. This article presents neuroimaging findings demonstrating that subjective pain unpleasantness ratings are associated with different pain-evoked brain responses in men and women, which has potentially important implications regarding sex differences in the risk of developing chronic pain. Copyright © 2014 American Pain Society. Published by Elsevier Inc. All rights reserved.

Contribution of Vestibular-Evoked Myogenic Potential (VEMP) testing in the assessment and the differential diagnosis of otosclerosis

PubMed Central

Tramontani, Ourania; Gkoritsa, Eleni; Ferekidis, Eleftherios; Korres, Stavros G.

2014-01-01

Background The aim of this prospective clinical study was to evaluate the clinical importance of Vestibular-Evoked Myogenic Potentials (VEMPs) in the assessment and differential diagnosis of otosclerosis and otologic diseases characterized by “pseudo-conductive” components. We also investigated the clinical appearance of balance disorders in patients with otosclerosis by correlating VEMP results with the findings of caloric testing and pure tone audiometry(PTA). Material/Methods Air-conducted(AC) 4-PTA, bone-conducted(BC) 4-PTA, air-bone Gap(ABG), AC, BC tone burst evoked VEMP, and calorics were measured preoperatively in 126 otosclerotic ears. Results The response rate of the AC-VEMPs and BC-VEMPs was 29.36% and 44.03%, respectively. Statistical differences were found between the means of ABG, AC 4-PTA, and BC 4-PTA in the otosclerotic ears in relation to AC-VEMP elicitability. About one-third of patients presented with disequilibrium. A statistically significant interaction was found between calorics and dizziness in relation to PTA thresholds. No relationship was found between calorics and dizziness with VEMPs responses. Conclusions AC and BC VEMPs can be elicited in ears with otosclerosis. AC-VEMP is more vulnerable to conductive hearing loss. Evaluation of AC-VEMP thresholds can be added in the diagnostic work-up of otosclerosis in case of doubt, enhancing differential diagnosis in patients with air-bone gaps. Otosclerosis is not a cause of canal paresis or vertigo. PMID:24509900

Neurophysiological mechanism of possibly confounding peripheral activation of the facial nerve during corticobulbar tract monitoring.

PubMed

Téllez, Maria J; Ulkatan, Sedat; Urriza, Javier; Arranz-Arranz, Beatriz; Deletis, Vedran

2016-02-01

To improve the recognition and possibly prevent confounding peripheral activation of the facial nerve caused by leaking transcranial electrical stimulation (TES) current during corticobulbar tract monitoring. We applied a single stimulus and a short train of electrical stimuli directly to the extracranial portion of the facial nerve. We compared the peripherally elicited compound muscle action potential (CMAP) of the facial nerve with the responses elicited by TES during intraoperative monitoring of the corticobulbar tract. A single stimulus applied directly to the facial nerve at subthreshold intensities did not evoke a CMAP, whereas short trains of subthreshold stimuli repeatedly evoked CMAPs. This is due to the phenomenon of sub- or near-threshold super excitability of the cranial nerve. Therefore, the facial responses evoked by short trains TES, when the leaked current reaches the facial nerve at sub- or near-threshold intensity, could lead to false interpretation. Our results revealed a potential pitfall in the current methodology for facial corticobulbar tract monitoring that is due to the activation of the facial nerve by subthreshold trains of stimuli. This study proposes a new criterion to exclude peripheral activation during corticobulbar tract monitoring. The failure to recognize and avoid facial nerve activation due to leaking current in the peripheral portion of the facial nerve during TES decreases the reliability of corticobulbar tract monitoring by increasing the possibility of false interpretation. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Separating neural and vascular effects of caffeine using simultaneous EEG–FMRI: Differential effects of caffeine on cognitive and sensorimotor brain responses

PubMed Central

Diukova, Ana; Ware, Jennifer; Smith, Jessica E.; Evans, C. John; Murphy, Kevin; Rogers, Peter J.; Wise, Richard G.

2012-01-01

The effects of caffeine are mediated through its non-selective antagonistic effects on adenosine A1 and A2A adenosine receptors resulting in increased neuronal activity but also vasoconstriction in the brain. Caffeine, therefore, can modify BOLD FMRI signal responses through both its neural and its vascular effects depending on receptor distributions in different brain regions. In this study we aim to distinguish neural and vascular influences of a single dose of caffeine in measurements of task-related brain activity using simultaneous EEG–FMRI. We chose to compare low-level visual and motor (paced finger tapping) tasks with a cognitive (auditory oddball) task, with the expectation that caffeine would differentially affect brain responses in relation to these tasks. To avoid the influence of chronic caffeine intake, we examined the effect of 250 mg of oral caffeine on 14 non and infrequent caffeine consumers in a double-blind placebo-controlled cross-over study. Our results show that the task-related BOLD signal change in visual and primary motor cortex was significantly reduced by caffeine, while the amplitude and latency of visual evoked potentials over occipital cortex remained unaltered. However, during the auditory oddball task (target versus non-target stimuli) caffeine significantly increased the BOLD signal in frontal cortex. Correspondingly, there was also a significant effect of caffeine in reducing the target evoked response potential (P300) latency in the oddball task and this was associated with a positive potential over frontal cortex. Behavioural data showed that caffeine also improved performance in the oddball task with a significantly reduced number of missed responses. Our results are consistent with earlier studies demonstrating altered flow-metabolism coupling after caffeine administration in the context of our observation of a generalised caffeine-induced reduction in cerebral blood flow demonstrated by arterial spin labelling (19% reduction over grey matter). We were able to identify vascular effects and hence altered neurovascular coupling through the alteration of low-level task FMRI responses in the face of a preserved visual evoked potential. However, our data also suggest a cognitive effect of caffeine through its positive effect on the frontal BOLD signal consistent with the shortening of oddball EEG response latency. The combined use of EEG–FMRI is a promising methodology for investigating alterations in brain function in drug and disease studies where neurovascular coupling may be altered on a regional basis. PMID:22561357

Peripheral functional organisation of vagally evoked gastric motor responses in the ferret.

PubMed Central

Andrews, P L; Lawes, I N; Bower, A J

1980-01-01

The aims of the present study were to determine the relative amplitudes of intragastric motor responses evoked by different vagal branches and to establish whether the effects of acute or chronic vagotomy could be predicted from these data. Intragastric pressure responses to electrical stimulation of the vagus were measured in urethane-anaesthetised ferrets and acute or chronic vagotomies were performed. The results show that the left and right cervical vagi were equipotential and fully overlaped each other. Their contributions to the dorsal trunk were equipotential and fully overlapping and so were their contributions to the ventral trunk. The dorsal trunk was more effective than the ventral trunk and there was total functional overlap between these two trunks. Vagal evoked gastric motor responses of the ferret are apparently organised in a different way from vagally induced acid secretion or hormone release in the cat. Acute removal of a trunk led to a reduction in evoked responses that was not linear function of the effect of stimulation of that trunk. In contrast, chronic removal caused a relative increase in evoked responses that ws inversely related to the decrease caused by acute removal. The implications of total functional overlap and neuromuscular reorganisation after chronic vagotomy are discussed. PMID:7439800

An electromyographic study of muscle relaxants in man.

PubMed

Suzuki, H; Kanayama, T; Nakagawa, H; Yazaki, S; Shiratsuchi, T

1975-05-01

Supramaximal paired stimuli were applied to the ulnar nerve, and the amplitude of the muscle action potential evoked in the abductor digiti minimi by the second member of the stimulus pair (test response) was compared with that evoked by the first component (conditioning response). The interval between the two components of the stimulus pair (the pair interval) was increased stepwise from 7 to 100 msec and a curve (recovery curve) was obtained by relating the changes in pair interval to the difference in amplitude of the test and conditioning responses. Alterations of the recovery curve (RC) during partial paralysis by muscle relaxants were investigated in healthy adult patients under the lightest plane of general anaesthesia. The control curve obtained in 32 subjects before the administration of a muscle relaxant drug was characterized by slight depressions at very short intervals of paired stimuli, followed by a slight potentiation at 20-100 msec. With non-depolarizing relaxants, RC altered to the characteristic pattern of potentiation at very short intervals of stimuli, followed by a notable depression at longer intervals. In depolarizing blocks with small doses of suxamethonium, the depression of RC at short intervals in the control was enhanced and the pattern of RC was different from that of non-depolarizing agents. When desensitization blocks were instigated by the i.v. administration of suxamethonium, the RC patterns were similar to those of competitive agents.

Act quickly, decide later: long-latency visual processing underlies perceptual decisions but not reflexive behavior.

PubMed

Jolij, Jacob; Scholte, H Steven; van Gaal, Simon; Hodgson, Timothy L; Lamme, Victor A F

2011-12-01

Humans largely guide their behavior by their visual representation of the world. Recent studies have shown that visual information can trigger behavior within 150 msec, suggesting that visually guided responses to external events, in fact, precede conscious awareness of those events. However, is such a view correct? By using a texture discrimination task, we show that the brain relies on long-latency visual processing in order to guide perceptual decisions. Decreasing stimulus saliency leads to selective changes in long-latency visually evoked potential components reflecting scene segmentation. These latency changes are accompanied by almost equal changes in simple RTs and points of subjective simultaneity. Furthermore, we find a strong correlation between individual RTs and the latencies of scene segmentation related components in the visually evoked potentials, showing that the processes underlying these late brain potentials are critical in triggering a response. However, using the same texture stimuli in an antisaccade task, we found that reflexive, but erroneous, prosaccades, but not antisaccades, can be triggered by earlier visual processes. In other words: The brain can act quickly, but decides late. Differences between our study and earlier findings suggesting that action precedes conscious awareness can be explained by assuming that task demands determine whether a fast and unconscious, or a slower and conscious, representation is used to initiate a visually guided response.

[Cortical potentials evoked to response to a signal to make a memory-guided saccade].

PubMed

Slavutskaia, M V; Moiseeva, V V; Shul'govskiĭ, V V

2010-01-01

The difference in parameters of visually guided and memory-guided saccades was shown. Increase in the memory-guided saccade latency as compared to that of the visually guided saccades may indicate the deceleration of saccadic programming on the basis of information extraction from the memory. The comparison of parameters and topography of evoked components N1 and P1 of the evoked potential on the signal to make a memory- or visually guided saccade suggests that the early stage of the saccade programming associated with the space information processing is performed predominantly with top-down attention mechanism before the memory-guided saccade and bottom-up mechanism before the visually guided saccade. The findings show that the increase in the latency of the memory-guided saccades is connected with decision making at the central stage of the saccade programming. We proposed that wave N2, which develops in the middle of the latent period of the memory-guided saccades, is correlated with this process. Topography and spatial dynamics of components N1, P1 and N2 testify that the memory-guided saccade programming is controlled by the frontal mediothalamic system of selective attention and left-hemispheric brain mechanisms of motor attention.

The Nature and Process of Development in Averaged Visually Evoked Potentials: Discussion on Pattern Structure.

ERIC Educational Resources Information Center

Izawa, Shuji; Mizutani, Tohru

This paper examines the development of visually evoked EEG patterns in retarded and normal subjects. The paper focuses on the averaged visually evoked potentials (AVEP) in the central and occipital regions of the brain in eyes closed and eyes open conditions. Wave pattern, amplitude, and latency are examined. The first section of the paper reviews…

What a Nostril Knows: Olfactory Nerve-Evoked AMPA Responses Increase while NMDA Responses Decrease at 24-h Post-Training for Lateralized Odor Preference Memory in Neonate Rat

ERIC Educational Resources Information Center

Yuan, Qi; Harley, Carolyn W.

2012-01-01

Increased AMPA signaling is proposed to mediate long-term memory. Rat neonates acquire odor preferences in a single olfactory bulb if one nostril is occluded at training. Memory testing here confirmed that only trained bulbs support increased odor preference at 24 h. Olfactory nerve field potentials were tested at 24 h in slices from trained and…

αConotoxin ArIB[V11L,V16D] is a potent and selective antagonist at rat and human native α7 nicotinic acetylcholine receptors

PubMed Central

Innocent, Neal; Livingstone, Phil D.; Hone, Arik; Kimura, Atsuko; Young, Tracey; Whiteaker, Paul; McIntosh, J. Michael; Wonnacott, Susan

2008-01-01

A recently developed α-conotoxin, α-CtxArIB[V11L,V16D] is a potent and selective competitive antagonist at rat recombinant α7 nicotinic acetylcholine receptors (nAChRs), making it an attractive probe for this receptor subtype. α7 nAChRs are potential therapeutic targets that are widely expressed in both neuronal and non-neuronal tissues where they are implicated in a variety of functions. Here we evaluate this toxin at rat and human native nAChRs. Functional α7 nAChR responses were evoked by choline plus the allosteric potentiator PNU-120596 in rat PC12 cells and human SHSY5Y cells loaded with calcium indicators. α-CtxArIB[V11L,V16D] specifically inhibited α7 nAChR-mediated increases in Ca2+ in PC12 cells. Responses to other stimuli (5-iodo-A-85380, nicotine or KCl) that did not activate α7 nAChRs were unaffected. Human α7 nAChRs were also sensitive to α-CtxArIB[V11L,V16D]: ACh-evoked currents in X. laevis oocytes expressing human α7 nAChRs were inhibited by α-CtxArIB[V11L,V16D] (IC50 3.4 nM) in a slowly reversible manner, with full recovery taking 15 min. This is consistent with the timecourse of recovery from blockade of rat α7 nAChRs in PC12 cells. α-CtxArIB[V11L,V16D] inhibited human native α7 nAChRs in SHSY5Y cells, activated by either choline or AR-R17779 plus PNU-120596. Rat brain α7 nAChRs contribute to dopamine release from striatal minces: α-CtxArIB[V11L,V16D] (300 nM) selectively inhibited choline-evoked dopamine release without affecting responses evoked by nicotine that activates heteromeric nAChRs. This study establishes that α-CtxArIB[V11L,V16D] selectively inhibits human and rat native α7 nAChRs with comparable potency, making this a potentially useful antagonist for investigating α7 nAChR functions. PMID:18664588

Nociceptin/orphanin FQ decreases glutamate transmission and blocks ethanol-induced effects in the central amygdala of naive and ethanol-dependent rats.

PubMed

Kallupi, Marsida; Varodayan, Florence P; Oleata, Christopher S; Correia, Diego; Luu, George; Roberto, Marisa

2014-04-01

The central nucleus of the amygdala (CeA) mediates several addiction-related processes and nociceptin/orphanin FQ (nociceptin) regulates ethanol intake and anxiety-like behaviors. Glutamatergic synapses, in the CeA and throughout the brain, are very sensitive to ethanol and contribute to alcohol reinforcement, tolerance, and dependence. Previously, we reported that in the rat CeA, acute and chronic ethanol exposures significantly decrease glutamate transmission by both pre- and postsynaptic actions. In this study, using electrophysiological techniques in an in vitro CeA slice preparation, we investigated the effects of nociceptin on glutamatergic transmission and its interaction with acute ethanol in naive and ethanol-dependent rats. We found that nociceptin (100-1000 nM) diminished basal-evoked compound glutamatergic receptor-mediated excitatory postsynaptic potentials (EPSPs) and spontaneous and miniature EPSCs (s/mEPSCs) by mainly decreasing glutamate release in the CeA of naive rats. Notably, nociceptin blocked the inhibition induced by acute ethanol (44 mM) and ethanol blocked the nociceptin-induced inhibition of evoked EPSPs in CeA neurons of naive rats. In neurons from chronic ethanol-treated (ethanol-dependent) rats, the nociceptin-induced inhibition of evoked EPSP amplitude was not significantly different from that in naive rats. Application of [Nphe1]Nociceptin(1-13)NH2, a nociceptin receptor (NOP) antagonist, revealed tonic inhibitory activity of NOP on evoked CeA glutamatergic transmission only in ethanol-dependent rats. The antagonist also blocked nociceptin-induced decreases in glutamatergic responses, but did not affect ethanol-induced decreases in evoked EPSP amplitude. Taken together, these studies implicate a potential role for the nociceptin system in regulating glutamatergic transmission and a complex interaction with ethanol at CeA glutamatergic synapses.

Development of GABA-sensitive spasticity and rigidity in rats after transient spinal cord ischemia: a qualitative and quantitative electrophysiological and histopathological study.

PubMed

Kakinohana, O; Hefferan, M P; Nakamura, S; Kakinohana, M; Galik, J; Tomori, Z; Marsala, J; Yaksh, T L; Marsala, M

2006-09-01

Transient spinal cord ischemia may lead to a progressive degeneration of spinal interneurons and subsequently to increased hind limb motor tone. In the present work we sought to characterize the rigidity and spasticity components of this altered motor function by: i) tonic electromyographic activity measured in gastrocnemius muscle before and after ischemia, ii) measurement of muscle resistance during the period of ankle flexion and corresponding changes in electromyographic activity, iii) changes in Hoffmann reflex, and, iv) motor evoked potentials. In addition the effect of intrathecal treatment with baclofen (GABAB receptor agonist; 1 microg), nipecotic acid (GABA uptake inhibitor; 300 microg) and dorsal L2-L5 rhizotomy on spasticity and rigidity was studied. Finally, the changes in spinal choline acetyltransferase (ChAT) and vesicular glutamate transporter 2 and 1 (VGLUT2 and VGLUT1) expression were characterized using immunofluorescence and confocal microscopy. At 3-7 days after ischemia an increase in tonic electromyographic activity with a variable degree of rigidity was seen. In animals with modest rigidity a velocity-dependent increase in muscle resistance and corresponding appearance in electromyographic activity (consistent with the presence of spasticity) was measured during ankle rotation (4-612 degrees /s rotation). Measurement of the H-reflex revealed a significant increase in Hmax/Mmax ratio and a significant loss of rate-dependent inhibition. In the same animals a potent increase in motor evoked potential amplitudes was measured and this change correlated positively with the increased H-reflex responses. Spasticity and rigidity were consistently present for a minimum of 3 months after ischemia. Intrathecal treatment with baclofen (GABA B receptor agonist) and nipecotic acid (GABA uptake inhibitor) provided a significant suppression of spasticity, rigidity, H-reflex or motor evoked potentials. Dorsal L2-L5 rhizotomy significantly decreased muscle resistance but had no effect on increased amplitudes of motor evoked potentials. Confocal analysis of spinal cord sections at 8 weeks-12 months after ischemia revealed a continuing presence of ChAT positive alpha-motoneurons, Ia afferents and VGLUT2 and VGLUT1-positive terminals but a selective loss of small presumably inhibitory interneurons between laminae V-VII. These data demonstrate that brief transient spinal cord ischemia in rat leads to a consistent development of spasticity and rigidity. The lack of significant suppressive effect of dorsal L2-L5 rhizotomy on motor evoked potentials response indicates that descending motor input into alpha-motoneurons is independent on Ia afferent couplings and can independently contribute to increased alpha-motoneuronal excitability. The pharmacology of this effect emphasizes the potent role of GABAergic type B receptors in regulating both the spasticity and rigidity.

Evidence that NMDA-dependent limbic neural plasticity in the right hemisphere mediates pharmacological stressor (FG-7142)-induced lasting increases in anxiety-like behavior. Study 1--Role of NMDA receptors in efferent transmission from the cat amygdala.

PubMed

Adamec, R E

1998-01-01

The anxiogenic beta-carboline, FG-7142, produces intense anxiety in humans and anxiety-like behavior in animals. FG-7142 also mimics the effects of exogenous stressors. In cats, FG-7142 lastingly changes defensive and aggressive behavior. Long-term potentiation (LTP) of neural transmission between limbic structures known to modulate feline defensive response to threat accompany behavioral changes. A series of three reports describes experiments designed to test the hypothesis that behavioral changes depend upon an N-methyl-D-aspartate (NMDA) receptor-based LTP of efferent transmission from the amygdala. This first study characterizes the dose and time effects of injection of the NMDA receptor blocker 7-amino-phosphono-heptanoic acid (AP7) on efferent transmission from the cat amygdala to the ventromedial hypothalamus (VMH). Effects of doses of 0.5-10mg/kg (i.v.) of AP7 on potentials evoked in the VMH by single pulse stimulation of the basal amygdala were examined. In order to localize the action of the drug, concurrent measurements were taken of potentials evoked in the VMH by stimulation of the efferent fibers from the amygdala to the VMH (ventral amygdalofugal pathway, VAF). There was a dose-dependent reduction in the amygdalo-VMH evoked potential. The greatest reduction occurred at 5 mg/kg. Effects peaked at 10 min, and persisted for at least 1 h after injection. In contrast, AP7 increased the VAF-VMH-evoked potential at 10 min after injection, with a maximal increase at 5mg/kg. The data suggest that NMDA receptors intrinsic to the amygdala modulate excitatory efferent transmission from amygdala to VMH in the cat. It is speculated that a glutamatergic projection to gamma-aminobutyric acid tonic inhibitory systems in the VMH accounts for the VAF-VMH results.

Hyper-excitability of brainstem pathways in cerebral palsy.

PubMed

Smith, Allison Teresa; Gorassini, Monica Ann

2018-06-27

Individuals with cerebral palsy (CP) experience impairments in the control of head and neck movements, suggesting dysfunction in brainstem circuitry. To examine if brainstem circuitry is altered in CP we compared reflexes evoked in the sternocleidomastoid (SCM) muscle by trigeminal nerve stimulation in adults with CP and age/sex-matched controls. Increasing the intensity of trigeminal nerve stimulation produced progressive increases in the long-latency suppression of ongoing SCM EMG in controls. In contrast, participants with CP showed progressively increased facilitation around the same reflex window, suggesting heightened excitability of brainstem pathways. We also examined if there was altered activation of cortico-brainstem pathways in response to pre-natal injury of the brain. Motor-evoked potentials (MEPs) in the SCM that were conditioned by a prior trigeminal afferent stimulation were more facilitated in CP compared to controls, especially in ipsilateral MEPs that are likely mediated by cortico-reticulospinal pathways. In some participants with CP, but not in controls, a combined trigeminal nerve and cortical stimulation near threshold intensities produced large, long-lasting responses in both the SCM and biceps brachii muscles. We propose that the enhanced excitatory responses evoked from trigeminal and cortical inputs in CP are produced by heightened excitability of brainstem circuits, resulting in the augmented activation of reticulospinal pathways. Enhanced activation of reticulospinal pathways in response to early injury of the corticospinal tract may provide a compensated activation of the spinal cord, or alternatively, contribute to impairments in the precise control of head and neck functions.

Dehydroepiandrosterone Potentiates Native Ionotropic ATP Receptors Containing the P2X2 Subunit in Rat Sensory Neurones

PubMed Central

De Roo, Mathias; Rodeau, Jean-Luc; Schlichter, Rémy

2003-01-01

We have studied the modulatory effect of dehydroepiandrosterone (DHEA), the most abundant neurosteroid produced by glial cells and neurones, on membrane currents induced by the activation of ionotropic ATP (P2X) receptors in neonatal rat dorsal root ganglion neurones. ATP (1 μm) induced three types of currents/responses termed F (fast and transient), S (slowly desensitizing) and M (mixed, sum of F- and S-type responses). DHEA (10 nm to 100 μm) concentration-dependently increased the amplitude of plateau-like currents of S- and M-type responses evoked by submaximal (1 μm) but not saturating (100 μm or 1 mM) concentrations of ATP. αβ-Methylene ATP (αβme-ATP, 5 μm) also evoked F-, S- and M-type responses, the plateau phases of which were potentiated by lowering external pH (6.3) and by ivermectin (IVM, 3 μm), indicating the presence heteromeric P2X2-containing receptors and possibly of functional native P2X4/6 receptors. There was a strict correlation between the potentiating effects of low pH and DHEA on αβme-ATP responses but not between that of IVM and DHEA, suggesting that DHEA selectively modulated P2X2-containing receptors. DHEA also potentiated putative homomeric P2X2 receptor responses recorded in the continuous presence of 1 μm 2′-(or 3′)-O-(2,4,6-trinitrophenyl) adenosine 5′-triphosphate (TNP-ATP). Our results constitute the first demonstration of a fast potentiation of P2X receptors by a neurosteroid and suggest that DHEA could be an endogenous modulator of P2X2-containing receptors thereby contributing to the facilitation of the detection and/or the transmission of nociceptive messages, particularly under conditions of inflammatory pain where the P2X receptor signalling pathway appears to be upregulated. PMID:12844512

Pulsed infrared radiation excites cultured neonatal spiral and vestibular ganglion neurons by modulating mitochondrial calcium cycling

PubMed Central

Lumbreras, Vicente; Bas, Esperanza; Gupta, Chhavi

2014-01-01

Cochlear implants are currently the most effective solution for profound sensorineural hearing loss, and vestibular prostheses are under development to treat bilateral vestibulopathies. Electrical current spread in these neuroprostheses limits channel independence and, in some cases, may impair their performance. In comparison, optical stimuli that are spatially confined may result in a significant functional improvement. Pulsed infrared radiation (IR) has previously been shown to elicit responses in neurons. This study analyzes the response of neonatal rat spiral and vestibular ganglion neurons in vitro to IR (wavelength = 1,863 nm) using Ca2+ imaging. Both types of neurons responded consistently with robust intracellular Ca2+ ([Ca2+]i) transients that matched the low-frequency IR pulses applied (4 ms, 0.25–1 pps). Radiant exposures of ∼637 mJ/cm2 resulted in continual neuronal activation. Temperature or [Ca2+] variations in the media did not alter the IR-evoked transients, ruling out extracellular Ca2+ involvement or primary mediation by thermal effects on the plasma membrane. While blockage of Na+, K+, and Ca2+ plasma membrane channels did not alter the IR-evoked response, blocking of mitochondrial Ca2+ cycling with CGP-37157 or ruthenium red reversibly inhibited the IR-evoked [Ca2+]i transients. Additionally, the magnitude of the IR-evoked transients was dependent on ryanodine and cyclopiazonic acid-dependent Ca2+ release. These results suggest that IR modulation of intracellular calcium cycling contributes to stimulation of spiral and vestibular ganglion neurons. As a whole, the results suggest selective excitation of neurons in the IR beam path and the potential of IR stimulation in future auditory and vestibular prostheses. PMID:24920028

Pulsed infrared radiation excites cultured neonatal spiral and vestibular ganglion neurons by modulating mitochondrial calcium cycling.

PubMed

Lumbreras, Vicente; Bas, Esperanza; Gupta, Chhavi; Rajguru, Suhrud M

2014-09-15

Cochlear implants are currently the most effective solution for profound sensorineural hearing loss, and vestibular prostheses are under development to treat bilateral vestibulopathies. Electrical current spread in these neuroprostheses limits channel independence and, in some cases, may impair their performance. In comparison, optical stimuli that are spatially confined may result in a significant functional improvement. Pulsed infrared radiation (IR) has previously been shown to elicit responses in neurons. This study analyzes the response of neonatal rat spiral and vestibular ganglion neurons in vitro to IR (wavelength = 1,863 nm) using Ca(2+) imaging. Both types of neurons responded consistently with robust intracellular Ca(2+) ([Ca(2+)]i) transients that matched the low-frequency IR pulses applied (4 ms, 0.25-1 pps). Radiant exposures of ∼637 mJ/cm(2) resulted in continual neuronal activation. Temperature or [Ca(2+)] variations in the media did not alter the IR-evoked transients, ruling out extracellular Ca(2+) involvement or primary mediation by thermal effects on the plasma membrane. While blockage of Na(+), K(+), and Ca(2+) plasma membrane channels did not alter the IR-evoked response, blocking of mitochondrial Ca(2+) cycling with CGP-37157 or ruthenium red reversibly inhibited the IR-evoked [Ca(2+)]i transients. Additionally, the magnitude of the IR-evoked transients was dependent on ryanodine and cyclopiazonic acid-dependent Ca(2+) release. These results suggest that IR modulation of intracellular calcium cycling contributes to stimulation of spiral and vestibular ganglion neurons. As a whole, the results suggest selective excitation of neurons in the IR beam path and the potential of IR stimulation in future auditory and vestibular prostheses. Copyright © 2014 the American Physiological Society.

Magnitude and Temporal Variability of Inter-stimulus EEG Modulate the Linear Relationship Between Laser-Evoked Potentials and Fast-Pain Perception

PubMed Central

Li, Linling; Huang, Gan; Lin, Qianqian; Liu, Jia; Zhang, Shengli; Zhang, Zhiguo

2018-01-01

The level of pain perception is correlated with the magnitude of pain-evoked brain responses, such as laser-evoked potentials (LEP), across trials. The positive LEP-pain relationship lays the foundation for pain prediction based on single-trial LEP, but cross-individual pain prediction does not have a good performance because the LEP-pain relationship exhibits substantial cross-individual difference. In this study, we aim to explain the cross-individual difference in the LEP-pain relationship using inter-stimulus EEG (isEEG) features. The isEEG features (root mean square as magnitude and mean square successive difference as temporal variability) were estimated from isEEG data (at full band and five frequency bands) recorded between painful stimuli. A linear model was fitted to investigate the relationship between pain ratings and LEP response for fast-pain trials on a trial-by-trial basis. Then the correlation between isEEG features and the parameters of LEP-pain model (slope and intercept) was evaluated. We found that the magnitude and temporal variability of isEEG could modulate the parameters of an individual's linear LEP-pain model for fast-pain trials. Based on this, we further developed a new individualized fast-pain prediction scheme, which only used training individuals with similar isEEG features as the test individual to train the fast-pain prediction model, and obtained improved accuracy in cross-individual fast-pain prediction. The findings could help elucidate the neural mechanism of cross-individual difference in pain experience and the proposed fast-pain prediction scheme could be potentially used as a practical and feasible pain prediction method in clinical practice. PMID:29904336

Interactions Between Dyspnea and the Brain Processing of Nociceptive Stimuli: Experimental Air Hunger Attenuates Laser-Evoked Brain Potentials in Humans.

PubMed

Dangers, Laurence; Laviolette, Louis; Similowski, Thomas; Morélot-Panzini, Capucine

2015-01-01

Dyspnea and pain share several characteristics and certain neural networks and interact with each other. Dyspnea-pain counter-irritation consists of attenuation of preexisting pain by intercurrent dyspnea and has been shown to have neurophysiological correlates in the form of inhibition of the nociceptive spinal reflex RIII and laser-evoked potentials (LEPs). Experimentally induced exertional dyspnea inhibits RIII and LEPs, while "air hunger" dyspnea does not inhibit RIII despite its documented analgesic effects. We hypothesized that air hunger may act centrally and inhibit LEPs. LEPs were obtained in 12 healthy volunteers (age: 21-29) during spontaneous breathing (FB), ventilator-controlled breathing (VC) tailored to FB, after inducing air hunger by increasing the inspired fraction of carbon dioxide -FiCO2- (VCCO2), and during ventilator-controlled breathing recovery (VCR). VCCO2 induced intense dyspnea (visual analog scale = 63% ± 6% of full scale, p < 0.001 vs. VC), predominantly of the air hunger type. VC alone reduced the amplitude of the N2-P2 component of LEPs (Δ = 24.0% ± 21.1%, p < 0.05, effect-size = 0.74) predominantly through a reduction in P2, and the amplitude of this inhibition was further reduced by inducting air hunger (Δ = 22.6% ± 17.9%, p < 0.05, effect-size = 0.53), predominantly through a reduction in N2. Somatosensory-evoked potentials (SEPs) were not affected by VC or VCCO2, suggesting that the observed effects are specific to pain transmission. We conclude that air hunger interferes with the cortical mechanisms responsible for the cortical response to painful laser skin stimulation, which provides a neurophysiological substrate to the central nature of its otherwise documented analgesic effects.

Alpha7 Nicotinic Acetylcholine Receptors Play a Predominant Role in the Cholinergic Potentiation of N-Methyl-D-Aspartate Evoked Firing Responses of Hippocampal CA1 Pyramidal Cells

PubMed Central

Bali, Zsolt K.; Nagy, Lili V.; Hernádi, István

2017-01-01

The aim of the present study was to identify in vivo electrophysiological correlates of the interaction between cholinergic and glutamatergic neurotransmission underlying memory. Extracellular spike recordings were performed in the hippocampal CA1 region of anesthetized rats in combination with local microiontophoretic administration of N-methyl-D-aspartate (NMDA) and acetylcholine (ACh). Both NMDA and ACh increased the firing rate of the neurons. Furthermore, the simultaneous delivery of NMDA and ACh resulted in a more pronounced excitatory effect that was superadditive over the sum of the two mono-treatment effects and that was explained by cholinergic potentiation of glutamatergic neurotransmission. Next, animals were systemically treated with scopolamine or methyllycaconitine (MLA) to assess the contribution of muscarinic ACh receptor (mAChR) or α7 nicotinic ACh receptor (nAChR) receptor-mediated mechanisms to the observed effects. Scopolamine totally inhibited ACh-evoked firing, and attenuated the firing rate increase evoked by simultaneous application of NMDA and ACh. However, the superadditive nature of the combined effect was preserved. The α7 nAChR antagonist MLA robustly decreased the firing response to simultaneous application of NMDA and ACh, suspending their superadditive effect, without modifying the tonic firing rate increasing effect of ACh. These results provide the first in vivo electrophysiological evidence that, in the hippocampal CA1 region, α7 nAChRs contribute to pyramidal cell activity mainly through potentiation of glutamatergic signaling, while the direct cholinergic modulation of tonic firing is notably mediated by mAChRs. Furthermore, the present findings also reveal cellular physiological correlates of the interplay between cholinergic and glutamatergic agents in behavioral pharmacological models of cognitive decline. PMID:28928637

Enhanced scratching evoked by PAR-2 agonist and 5-HT but not histamine in a mouse model of chronic dry skin itch.

PubMed

Akiyama, T; Carstens, M Iodi; Carstens, E

2010-11-01

Chronic itch is a symptom of many skin conditions and systemic disease, and it has been hypothesized that the chronic itch may result from sensitization of itch-signaling pathways. We induced experimental chronic dry skin on the rostral back of mice, and observed a significant increase in spontaneous hindlimb scratches directed to the dry skin. Spontaneous scratching was significantly attenuated by a PAR-2 antibody and 5-HT2A receptor antagonist, indicating activation of these receptors by endogenous mediators released under dry skin conditions. We also observed a significant increase in the number of scratch bouts evoked by acute intradermal injections of a protease-activated receptor (PAR)-2 agonist and serotonin (5-HT), but not histamine. We additionally investigated if pruritogen-evoked activity of dorsal root ganglion (DRG) neurons is enhanced in this model. DRG cells from dry skin mice exhibited significantly larger responses to the PAR-2 agonist and 5-HT, but not histamine. Spontaneous scratching may reflect ongoing itch, and enhanced pruritogen-evoked scratching may represent hyperknesis (enhanced itch), both potentially due to sensitization of itch-signaling neurons. The correspondence between enhanced behavioral scratching and DRG cell responses suggest that peripheral pruriceptors that respond to proteases and 5-HT, but not histamine, may be sensitized in dry skin itch. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

An Analysis of The Parameters Used In Speech ABR Assessment Protocols.

PubMed

Sanfins, Milaine D; Hatzopoulos, Stavros; Donadon, Caroline; Diniz, Thais A; Borges, Leticia R; Skarzynski, Piotr H; Colella-Santos, Maria Francisca

2018-04-01

The aim of this study was to assess the parameters of choice, such as duration, intensity, rate, polarity, number of sweeps, window length, stimulated ear, fundamental frequency, first formant, and second formant, from previously published speech ABR studies. To identify candidate articles, five databases were assessed using the following keyword descriptors: speech ABR, ABR-speech, speech auditory brainstem response, auditory evoked potential to speech, speech-evoked brainstem response, and complex sounds. The search identified 1288 articles published between 2005 and 2015. After filtering the total number of papers according to the inclusion and exclusion criteria, 21 studies were selected. Analyzing the protocol details used in 21 studies suggested that there is no consensus to date on a speech-ABR protocol and that the parameters of analysis used are quite variable between studies. This inhibits the wider generalization and extrapolation of data across languages and studies.

Simultaneous EEG/fMRI analysis of the resonance phenomena in steady-state visual evoked responses.

PubMed

Bayram, Ali; Bayraktaroglu, Zubeyir; Karahan, Esin; Erdogan, Basri; Bilgic, Basar; Ozker, Muge; Kasikci, Itir; Duru, Adil D; Ademoglu, Ahmet; Oztürk, Cengizhan; Arikan, Kemal; Tarhan, Nevzat; Demiralp, Tamer

2011-04-01

The stability of the steady-state visual evoked potentials (SSVEPs) across trials and subjects makes them a suitable tool for the investigation of the visual system. The reproducible pattern of the frequency characteristics of SSVEPs shows a global amplitude maximum around 10 Hz and additional local maxima around 20 and 40 Hz, which have been argued to represent resonant behavior of damped neuronal oscillators. Simultaneous electroencephalogram/functional magnetic resonance imaging (EEG/fMRI) measurement allows testing of the resonance hypothesis about the frequency-selective increases in SSVEP amplitudes in human subjects, because the total synaptic activity that is represented in the fMRI-Blood Oxygen Level Dependent (fMRI-BOLD) response would not increase but get synchronized at the resonance frequency. For this purpose, 40 healthy volunteers were visually stimulated with flickering light at systematically varying frequencies between 6 and 46 Hz, and the correlations between SSVEP amplitudes and the BOLD responses were computed. The SSVEP frequency characteristics of all subjects showed 3 frequency ranges with an amplitude maximum in each of them, which roughly correspond to alpha, beta and gamma bands of the EEG. The correlation maps between BOLD responses and SSVEP amplitude changes across the different stimulation frequencies within each frequency band showed no significant correlation in the alpha range, while significant correlations were obtained in the primary visual area for the beta and gamma bands. This non-linear relationship between the surface recorded SSVEP amplitudes and the BOLD responses of the visual cortex at stimulation frequencies around the alpha band supports the view that a resonance at the tuning frequency of the thalamo-cortical alpha oscillator in the visual system is responsible for the global amplitude maximum of the SSVEP around 10 Hz. Information gained from the SSVEP/fMRI analyses in the present study might be extrapolated to the EEG/fMRI analysis of the transient event-related potentials (ERPs) in terms of expecting more reliable and consistent correlations between EEG and fMRI responses, when the analyses are carried out on evoked or induced oscillations (spectral perturbations) in separate frequency bands instead of the time-domain ERP peaks.

The VERRUN and VERNAL software systems for steady-state visual evoked response experimentation

NASA Technical Reports Server (NTRS)

Levison, W. H.; Zacharias, G. L.

1984-01-01

Two digital computer programs were developed for use in experiments involving steady-state visual evoked response (VER): VERRUN, whose primary functions are to generate a sum-of-sines (SOS) stimulus and to digitize and store electro-cortical response; and VERNAL, which provides both time- and frequency-domain metrics of the evoked response. These programs were coded in FORTRAN for operation on the PDP-11/34, using the RSX-11 Operating System, and the PDP-11/23, using the RT-11 Operating System. Users' and programmers' guides to these programs are provided, and guidelines for model analysis of VER data are suggested.

Descriptive Linear modeling of steady-state visual evoked response

NASA Technical Reports Server (NTRS)

Levison, W. H.; Junker, A. M.; Kenner, K.

1986-01-01

A study is being conducted to explore use of the steady state visual-evoke electrocortical response as an indicator of cognitive task loading. Application of linear descriptive modeling to steady state Visual Evoked Response (VER) data is summarized. Two aspects of linear modeling are reviewed: (1) unwrapping the phase-shift portion of the frequency response, and (2) parsimonious characterization of task-loading effects in terms of changes in model parameters. Model-based phase unwrapping appears to be most reliable in applications, such as manual control, where theoretical models are available. Linear descriptive modeling of the VER has not yet been shown to provide consistent and readily interpretable results.

Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders.

PubMed

Venhovens, J; Meulstee, J; Verhagen, W I M

2016-01-01

Several types of acoustic stimulation (i.e. tone bursts or clicks), bone-conducted vibration, forehead taps, and galvanic stimulation elicit myogenic potentials. These can be recorded in cervical and ocular muscles, the so called vestibular evoked myogenic potentials (VEMPs). The cervical VEMP (cVEMP) resembles the vestibulo-collic reflex and the responses can be recorded from the ipsilateral sternocleidomastoid muscle. The ocular VEMP resembles the vestibulo-ocular reflex and can be recorded from extra-ocular muscles by a surface electrode beneath the contralateral infraorbital margin. Initially, the literature concerning VEMPs was limited to peripheral vestibular disorders, however, the field of VEMP testing is rapidly expanding, with an increasing focus on central neurological disorders. The current literature concerning VEMP abnormalities in central neurological disorders is critically reviewed, especially regarding the methodological aspects in relation to quality as well as the clinical interpretation of the VEMP results. Suggestions for further research are proposed as well as some clinically useful indications. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Unknown Pseudocholinesterase Deficiency in a Patient Undergoing TIVA with Planned Motor Evoked Potential Monitoring: A Case Report.

PubMed

Binkley, Candace

2016-06-01

Pseudocholinesterase abnormalities are a genetic cause of aberrant metabolism of the depolarizing muscle relaxant succinylcholine. This article examines a case where succinylcholine was chosen to facilitate intubation due to its ultra short duration and the request of the surgeon to monitor motor evoked potentials. Following succinylcholine administration the neurophysiologist was unable to obtain motor evoked potentials. This case study highlights the intraoperative and postoperative management of an elderly patient with an unknown pseudocholinesterase deficiency.

Common features of fluency-evoking conditions studied in stuttering subjects and controls: an H(2)15O PET study.

PubMed

Stager, Sheila V; Jeffries, Keith J; Braun, Allen R

2003-01-01

We used H(2)15O PET to characterize the common features of two successful but markedly different fluency-evoking conditions -- paced speech and singing -- in order to identify brain mechanisms that enable fluent speech in people who stutter. To do so, we compared responses under fluency-evoking conditions with responses elicited by tasks that typically elicit dysfluent speech (quantifying the degree of stuttering and using this measure as a confounding covariate in our analyses). We evaluated task-related activations in both stuttering subjects and age- and gender-matched controls. Areas that were either uniquely activated during fluency-evoking conditions, or in which the magnitude of activation was significantly greater during fluency-evoking than dysfluency-evoking tasks included auditory association areas that process speech and voice and motor regions related to control of the larynx and oral articulators. This suggests that a common fluency-evoking mechanism might relate to more effective coupling of auditory and motor systems -- that is, more efficient self-monitoring, allowing motor areas to more effectively modify speech. These effects were seen in both PWS and controls, suggesting that they are due to the sensorimotor or cognitive demands of the fluency-evoking tasks themselves. While responses seen in both groups were bilateral, however, the fluency-evoking tasks elicited more robust activation of auditory and motor regions within the left hemisphere of stuttering subjects, suggesting a role for the left hemisphere in compensatory processes that enable fluency. The reader will learn about and be able to: (1) compare brain activation patterns under fluency- and dysfluency-evoking conditions in stuttering and control subjects; (2) appraise the common features, both central and peripheral, of fluency-evoking conditions; and (3) discuss ways in which neuroimaging methods can be used to understand the pathophysiology of stuttering.

Human auditory evoked potentials in the assessment of brain function during major cardiovascular surgery.

PubMed

Rodriguez, Rosendo A

2004-06-01

Focal neurologic and intellectual deficits or memory problems are relatively frequent after cardiac surgery. These complications have been associated with cerebral hypoperfusion, embolization, and inflammation that occur during or after surgery. Auditory evoked potentials, a neurophysiologic technique that evaluates the function of neural structures from the auditory nerve to the cortex, provide useful information about the functional status of the brain during major cardiovascular procedures. Skepticism regarding the presence of artifacts or difficulty in their interpretation has outweighed considerations of its potential utility and noninvasiveness. This paper reviews the evidence of their potential applications in several aspects of the management of cardiac surgery patients. The sensitivity of auditory evoked potentials to the effects of changes in brain temperature makes them useful for monitoring cerebral hypothermia and rewarming during cardiopulmonary bypass. The close relationship between evoked potential waveforms and specific anatomic structures facilitates the assessment of the functional integrity of the central nervous system in cardiac surgery patients. This feature may also be relevant in the management of critical patients under sedation and coma or in the evaluation of their prognosis during critical care. Their objectivity, reproducibility, and relative insensitivity to learning effects make auditory evoked potentials attractive for the cognitive assessment of cardiac surgery patients. From a clinical perspective, auditory evoked potentials represent an additional window for the study of underlying cerebral processes in healthy and diseased patients. From a research standpoint, this technology offers opportunities for a better understanding of the particular cerebral deficits associated with patients who are undergoing major cardiovascular procedures.

A novel method of brainstem auditory evoked potentials using complex verbal stimuli.

PubMed

Kouni, Sophia N; Koutsojannis, Constantinos; Ziavra, Nausika; Giannopoulos, Sotirios

2014-08-01

The click and tone-evoked auditory brainstem responses are widely used in clinical practice due to their consistency and predictability. More recently, the speech-evoked responses have been used to evaluate subcortical processing of complex signals, not revealed by responses to clicks and tones. Disyllable stimuli corresponding to familiar words can induce a pattern of voltage fluctuations in the brain stem resulting in a familiar waveform, and they can yield better information about brain stem nuclei along the ascending central auditory pathway. We describe a new method with the use of the disyllable word "baba" corresponding to English "daddy" that is commonly used in many other ethnic languages spanning from West Africa to the Eastern Mediterranean all the way to the East Asia. This method was applied in 20 young adults institutionally diagnosed as dyslexic (10 subjects) or light dyslexic (10 subjects) who were matched with 20 sex, age, education, hearing sensitivity, and IQ-matched normal subjects. The absolute peak latencies of the negative wave C and the interpeak latencies of A-C elicited by verbal stimuli "baba" were found to be significantly increased in the dyslexic group in comparison with the control group. The method is easy and helpful to diagnose abnormalities affecting the auditory pathway, to identify subjects with early perception and cortical representation abnormalities, and to apply the suitable therapeutic and rehabilitation management.

Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

NASA Technical Reports Server (NTRS)

Hecox, K.; Squires, N.; Galambos, R.

1975-01-01

Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

Osteoarthritis-dependent changes in antinociceptive action of Nav1.7 and Nav1.8 sodium channel blockers: An in vivo electrophysiological study in the rat.

PubMed

Rahman, W; Dickenson, A H

2015-06-04

Voltage-gated sodium channel blockers are not traditionally recommended for osteoarthritis (OA) pain therapy, but given the large peripheral drive that follows OA development there is a rationale for their use. Using a rat model of monosodium iodoacetate (MIA)-induced OA we used in vivo electrophysiology to assess the effects of the Nav1.7- and Nav1.8-selective antagonists, ProTxII and A-803467 respectively, on the evoked activity of spinal dorsal horn neurons in response to electrical, mechanical and thermal stimuli applied to the peripheral receptive field. These studies allow examination of the roles of these channels in suprathreshold stimuli, not amenable to behavioral threshold measures. Spinal administration of ProTxII significantly reduced neuronal responses evoked by mechanical punctate (von Frey (vF) 8-60g) and noxious thermal (45 and 48°C) stimuli in MIA rats only. A-803467 significantly inhibited neuronal responses evoked by vF 8-60g and 48°C heat after spinal administration; significantly inhibited responses evoked by brush, vFs 26-60g and 40-48°C stimuli after systemic administration; significantly inhibited the electrically evoked Aδ-, C-fiber, post-discharge, Input and wind-up responses and the brush, vFs 8-60g and 45-48°C evoked neuronal responses after intra plantar injection in the MIA group. In comparison A-803467 effects in the sham group were minimal and included a reduction of the neuronal response evoked by vF 60g and 45°C heat stimulation after spinal administration, no effect after systemic administration and an inhibition of the evoked response to 45°C heat after intra plantar injection only. The observed selective inhibitory effect of ProTxII and A-803467 for the MIA-treated group suggests an increased role of Nav1.7 and 1.8 within nociceptive pathways in the arthritic condition, located at peripheral and central sites. These findings demonstrate the importance of, and add to, the mechanistic understanding of these channels in osteoarthritic pain. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Osteoarthritis-dependent changes in antinociceptive action of Nav1.7 and Nav1.8 sodium channel blockers: An in vivo electrophysiological study in the rat

PubMed Central

Rahman, W.; Dickenson, A.H.

2015-01-01

Voltage-gated sodium channel blockers are not traditionally recommended for osteoarthritis (OA) pain therapy, but given the large peripheral drive that follows OA development there is a rationale for their use. Using a rat model of monosodium iodoacetate (MIA)-induced OA we used in vivo electrophysiology to assess the effects of the Nav1.7- and Nav1.8-selective antagonists, ProTxII and A-803467 respectively, on the evoked activity of spinal dorsal horn neurons in response to electrical, mechanical and thermal stimuli applied to the peripheral receptive field. These studies allow examination of the roles of these channels in suprathreshold stimuli, not amenable to behavioral threshold measures. Spinal administration of ProTxII significantly reduced neuronal responses evoked by mechanical punctate (von Frey (vF) 8–60 g) and noxious thermal (45 and 48 °C) stimuli in MIA rats only. A-803467 significantly inhibited neuronal responses evoked by vF 8–60 g and 48 °C heat after spinal administration; significantly inhibited responses evoked by brush, vFs 26–60 g and 40–48 °C stimuli after systemic administration; significantly inhibited the electrically evoked Aδ-, C-fiber, post-discharge, Input and wind-up responses and the brush, vFs 8–60 g and 45–48 °C evoked neuronal responses after intra plantar injection in the MIA group. In comparison A-803467 effects in the sham group were minimal and included a reduction of the neuronal response evoked by vF 60 g and 45 °C heat stimulation after spinal administration, no effect after systemic administration and an inhibition of the evoked response to 45 °C heat after intra plantar injection only. The observed selective inhibitory effect of ProTxII and A-803467 for the MIA-treated group suggests an increased role of Nav1.7 and 1.8 within nociceptive pathways in the arthritic condition, located at peripheral and central sites. These findings demonstrate the importance of, and add to, the mechanistic understanding of these channels in osteoarthritic pain. PMID:25818052

Music-Evoked Emotions—Current Studies

PubMed Central

Schaefer, Hans-Eckhardt

2017-01-01

The present study is focused on a review of the current state of investigating music-evoked emotions experimentally, theoretically and with respect to their therapeutic potentials. After a concise historical overview and a schematic of the hearing mechanisms, experimental studies on music listeners and on music performers are discussed, starting with the presentation of characteristic musical stimuli and the basic features of tomographic imaging of emotional activation in the brain, such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), which offer high spatial resolution in the millimeter range. The progress in correlating activation imaging in the brain to the psychological understanding of music-evoked emotion is demonstrated and some prospects for future research are outlined. Research in psychoneuroendocrinology and molecular markers is reviewed in the context of music-evoked emotions and the results indicate that the research in this area should be intensified. An assessment of studies involving measuring techniques with high temporal resolution down to the 10 ms range, as, e.g., electroencephalography (EEG), event-related brain potentials (ERP), magnetoencephalography (MEG), skin conductance response (SCR), finger temperature, and goose bump development (piloerection) can yield information on the dynamics and kinetics of emotion. Genetic investigations reviewed suggest the heredity transmission of a predilection for music. Theoretical approaches to musical emotion are directed to a unified model for experimental neurological evidence and aesthetic judgment. Finally, the reports on musical therapy are briefly outlined. The study concludes with an outlook on emerging technologies and future research fields. PMID:29225563

[Origin of acoustically evoked short latency negative response in guinea pigs].

PubMed

Huang, Wen-qin; Qin, Huan-hua; Nong, Dong-xiao; Tang, An-zhou; Li, Zhi-mei; Yang, Tian

2011-04-01

To establish a model of acoustically evoked short latency negative response (ASNR) in guinea pigs, a model of profound hearing loss with normal saccular functions, and verify the correlation between ASNR and vestibular evoked myogenic potential (VEMP). Thirty-two healthy guinea pigs were employed in the experiment, which were randomly divided into control group (16 subjects) and deafened group (16 subjects). Each animal experienced auditory and vestibular tests including auditory brainstem response (ABR), VEMP and caloric test. A quick treatment was employed for deafened group consisting of a subcutaneous injection of kanamycin at a dose of 400 mg/kg followed by a jugular vein injection of ethacrynic acid at a dose of 40 mg/kg one hour later. The animals were received ABR, VEMP and caloric test 7 - 10 days following the drug administration. The deafened group was further divided into ASNR group and non-ASNR group, based on the presence of ASNR. In deafened group, five subjects died postoperatively, 11 subjects (22 ears) provided full data, ASNR was elicited in eight ears (36.4%), the threshold was 120 - 130 dB SPL with mean of (124.4 ± 4.96) dB SPL. Its latency range was 1.75 - 2.60 ms with mean of (2.15 ± 0.27) ms. The mean latency of threshold was (2.34 ± 0.18) ms. All eight ASNR ears presented with VEMP. The VEMP threshold, positive and negative potential latencies proved no statistical difference (P > 0.05) between ASNR group and control group. Significant difference was detected between the VEMP presence of ASNR group and non-ASNR group (P = 0.002). There was no statistically significant correlation between VEMP and caloric test neither between ASNR and caloric test in deafened group. This study evoked ASNR in an ototoxicity guinea pig model which has profound hearing loss with normal saccular functions. The presence of ASNR correlated with VEMP, however, not correlated with caloric test, suggesting that ASNR and VEMP are both originated from the saccule.

Behavioral analyses of wind-evoked escape of the cricket, Gryllodes sigillatus.

PubMed

Kanou, Masamichi; Konishi, Atsuko; Suenaga, Rie

2006-04-01

The wind-evoked escape behavior of the cricket Gryllodes sigillatus was investigated using an air puff stimulus. A high velocity air puff elicited the escape behavior in many crickets. The crickets tended to escape away from the stimulus source, but the direction was not accurately oriented 180 degrees from the stimulus. After bilateral cercal ablation, only a few crickets showed wind-evoked escape behavior, and their response rates did not increase even 19 days after ablation. Therefore, information on air motion detected by cercal filiform hairs is essential for triggering wind-evoked behavior. After unilateral cercal ablation, the 81.3% response rate of intact crickets decreased to 16.5%, that is, it decreased to almost 20% that of intact crickets. One week after unilateral cercal ablation, the response rate recovered to more than 60% that of intact crickets. However, the accuracy rate of the escape direction of G. sigillatus showed no change even immediately after the unilateral cercal ablation. Therefore, both cerci are not necessarily required to determine the escape direction. The behavioral characteristics of wind-evoked escape of G. sigillatus are compared with those of another species of cricket, Gryllus bimaculatus. The two species of cricket employ different strategies for wind-evoked escape.

Effects of rotation on the sleep state-dependent midlatency auditory evoked P50 potential in the human

NASA Technical Reports Server (NTRS)

Dornhoffer, John L.; Mamiya, N.; Bray, P.; Skinner, Robert D.; Garcia-Rill, Edgar

2002-01-01

Sopite syndrome, characterized by loss of initiative, sensitivity to normally innocuous sensory stimuli, and impaired concentration amounting to a sensory gating deficit, is commonly associated with Space Motion Sickness (SMS). The amplitude of the P50 potential is a measure of level of arousal, and a paired-stimulus paradigm can be used to measure sensory gating. We used the rotary chair to elicit the sensory mismatch that occurs with SMS by overstimulating the vestibular apparatus. The effects of rotation on the manifestation of the P50 midlatency auditory evoked response were then assessed as a measure of arousal and distractibility. Results showed that rotation-induced motion sickness produced no change in the level of arousal but did produce a significant deficit in sensory gating, indicating that some of the attentional and cognitive deficits observed with SMS may be due to distractibility induced by decreased habituation to repetitive stimuli.

Visual evoked potentials and selective attention to points in space

NASA Technical Reports Server (NTRS)

Van Voorhis, S.; Hillyard, S. A.

1977-01-01

Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

Addition of visual noise boosts evoked potential-based brain-computer interface.

PubMed

Xie, Jun; Xu, Guanghua; Wang, Jing; Zhang, Sicong; Zhang, Feng; Li, Yeping; Han, Chengcheng; Li, Lili

2014-05-14

Although noise has a proven beneficial role in brain functions, there have not been any attempts on the dedication of stochastic resonance effect in neural engineering applications, especially in researches of brain-computer interfaces (BCIs). In our study, a steady-state motion visual evoked potential (SSMVEP)-based BCI with periodic visual stimulation plus moderate spatiotemporal noise can achieve better offline and online performance due to enhancement of periodic components in brain responses, which was accompanied by suppression of high harmonics. Offline results behaved with a bell-shaped resonance-like functionality and 7-36% online performance improvements can be achieved when identical visual noise was adopted for different stimulation frequencies. Using neural encoding modeling, these phenomena can be explained as noise-induced input-output synchronization in human sensory systems which commonly possess a low-pass property. Our work demonstrated that noise could boost BCIs in addressing human needs.

Social vision: sustained perceptual enhancement of affective facial cues in social anxiety

PubMed Central

McTeague, Lisa M.; Shumen, Joshua R.; Wieser, Matthias J.; Lang, Peter J.; Keil, Andreas

2010-01-01

Heightened perception of facial cues is at the core of many theories of social behavior and its disorders. In the present study, we continuously measured electrocortical dynamics in human visual cortex, as evoked by happy, neutral, fearful, and angry faces. Thirty-seven participants endorsing high versus low generalized social anxiety (upper and lower tertiles of 2,104 screened undergraduates) viewed naturalistic faces flickering at 17.5 Hz to evoke steady-state visual evoked potentials (ssVEPs), recorded from 129 scalp electrodes. Electrophysiological data were evaluated in the time-frequency domain after linear source space projection using the minimum norm method. Source estimation indicated an early visual cortical origin of the face-evoked ssVEP, which showed sustained amplitude enhancement for emotional expressions specifically in individuals with pervasive social anxiety. Participants in the low symptom group showed no such sensitivity, and a correlational analysis across the entire sample revealed a strong relationship between self-reported interpersonal anxiety/avoidance and enhanced visual cortical response amplitude for emotional, versus neutral expressions. This pattern was maintained across the 3500 ms viewing epoch, suggesting that temporally sustained, heightened perceptual bias towards affective facial cues is associated with generalized social anxiety. PMID:20832490

Development of somatosensory-evoked potentials in foetal sheep: effects of betamethasone.

PubMed

Anegroaie, P; Frasch, M G; Rupprecht, S; Antonow-Schlorke, I; Müller, T; Schubert, H; Witte, O W; Schwab, M

2017-05-01

Antenatal glucocorticoids are used to accelerate foetal lung maturation in babies threatened with premature labour. We examined the influence of glucocorticoids on functional and structural maturation of the central somatosensory pathway in foetal sheep. Somatosensory-evoked potentials (SEP) reflect processing of somatosensory stimuli. SEP latencies are determined by afferent stimuli transmission while SEP amplitudes reveal cerebral processing. After chronic instrumentation of foetal sheep, mothers received saline (n = 9) or three courses of betamethasone (human equivalent dose of 2 × 110 μg kg -1 betamethasone i.m. 24 h apart, n = 12) at 0.7, 0.75 and 0.8 of gestational age. Trigeminal SEP were evoked prior to, 4 and 24 h after each injection and at 0.8 of gestational age before brains were histologically processed. Somatosensory-evoked potentials were already detectable at 0.7 of gestation age. The early and late responses N20 and N200 were the only reproducible peaks over the entire study period. With advancing gestational age, SEP latencies decreased but amplitudes remained unchanged. Acutely, betamethasone did not affect SEP latencies and amplitudes 4 and 24 h following administration. Chronically, betamethasone delayed developmental decrease in the N200 but not N20 latency by 2 weeks without affecting amplitudes. In parallel, betamethasone decreased subcortical white matter myelination but did not affect network formation and synaptic density in the somatosensory cortex. Somatosensory stimuli are already processed by the foetal cerebral cortex at the beginning of the third trimester. Subsequent developmental decrease in SEP latencies suggests ongoing maturation of afferent sensory transmission. Antenatal glucocorticoids affect structural and functional development of the somatosensory system with specific effects at subcortical level. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Sub- and suprathreshold receptive field properties of pyramidal neurones in layers 5A and 5B of rat somatosensory barrel cortex

PubMed Central

Manns, Ian D; Sakmann, Bert; Brecht, Michael

2004-01-01

Layer 5 (L5) pyramidal neurones constitute a major sub- and intracortical output of the somatosensory cortex. This layer 5 is segregated into layers 5A and 5B which receive and distribute relatively independent afferent and efferent pathways. We performed in vivo whole-cell recordings from L5 neurones of the somatosensory (barrel) cortex of urethane-anaesthetized rats (aged 27–31 days). By delivering 6 deg single whisker deflections, whisker pad receptive fields were mapped for 16 L5A and 11 L5B neurones located below the layer 4 whisker-barrels. Average resting membrane potentials were −75.6±1.1 mV, and spontaneous action potential (AP) rates were 0.54± 0.14 APs s−1. Principal whisker (PW) evoked responses were similar in L5A and L5B neurones, with an average 5.0 ± 0.6 mV postsynaptic potential (PSP) and 0.12 ± 0.03 APs per stimulus. The layer 5A sub- and suprathreshold receptive fields (RFs) were more confined to the principle whisker than those of layer 5B. The basal dendritic arbors of layer 5A and 5B cells were located below both layer 4 barrels and septa, and the cell bodies were biased towards the barrel walls. Responses in both L5A and L5B developed slowly, with onset latencies of 10.1 ± 0.5 ms and peak latencies of 33.9 ± 3.3 ms. Contralateral multi-whisker stimulation evoked PSPs similar in amplitude to those of PW deflections; whereas, ipsilateral stimulation evoked smaller and longer latency PSPs. We conclude that in L5 a whisker deflection is represented in two ways: focally by L5A pyramids and more diffusely by L5B pyramids as a result of combining different inputs from lemniscal and paralemniscal pathways. The relevant output evoked by a whisker deflection could be the ensemble activity in the anatomically defined cortical modules associated with a single or a few barrel-columns. PMID:14724202

Evoking/Interpreting Literature through Visualizing Roles.

ERIC Educational Resources Information Center

Karolides, Nicholas J.

Differences in readers' interpretations of a given text illustrate premises of the transactional or reader response theory of literature. The theory holds that: (1) meaning resides in the coming together of reader and text; (2) the reader affects the reading of the text and is affected by the text; and (3) there are potentially as many meanings to…

Brief Report: Early VEPs to Pattern-Reversal in Adolescents and Adults with Autism

ERIC Educational Resources Information Center

Kovarski, K.; Thillay, A.; Houy-Durand, E.; Roux, S.; Bidet-Caulet, A.; Bonnet-Brilhault, F.; Batty, M.

2016-01-01

Autism spectrum disorder (ASD) is characterized by atypical visual perception both in the social and nonsocial domain. In order to measure a reliable visual response, visual evoked potentials were recorded during a passive pattern-reversal stimulation in adolescents and adults with and without ASD. While the present results show the same…

[Effect of GABA, sodium glutamate and glycine on evoked potentials in the dental zones of the cerebral cortex].

PubMed

Degtiarev, V P

1979-01-01

Intraventricular administration of gamma-aminobutyric acid (GABA) and glycine decreased, whereas sodium glutamate increased the amplitude of primary responses of dental zones of the somatosensory cortex, which arose during electric stimulation of the pulp of the rabbit upper incisors. No changes in the latent periods were recorded.

Auditory Long Latency Responses to Tonal and Speech Stimuli

ERIC Educational Resources Information Center

Swink, Shannon; Stuart, Andrew

2012-01-01

Purpose: The effects of type of stimuli (i.e., nonspeech vs. speech), speech (i.e., natural vs. synthetic), gender of speaker and listener, speaker (i.e., self vs. other), and frequency alteration in self-produced speech on the late auditory cortical evoked potential were examined. Method: Young adult men (n = 15) and women (n = 15), all with…

Altered Evoked Gamma-Band Responses Reveal Impaired Early Visual Processing in ADHD Children

ERIC Educational Resources Information Center

Lenz, Daniel; Krauel, Kerstin; Flechtner, Hans-Henning; Schadow, Jeanette; Hinrichs, Hermann; Herrmann, Christoph S.

2010-01-01

Neurophysiological studies yield contrary results whether attentional problems of patients with attention-deficit/hyperactivity disorder (ADHD) are related to early visual processing deficits or not. Evoked gamma-band responses (GBRs), being among the first cortical responses occurring as early as 90 ms after visual stimulation in human EEG, have…

Auditory evoked potentials.

PubMed

De Cosmo, G; Aceto, P; Clemente, A; Congedo, E

2004-05-01

Auditory evoked potentials (AEPs) are an electrical manifestation of the brain response to an auditory stimulus. Mid-latency auditory evoked potentials (MLAEPs) and the coherent frequency of the AEP are the most promising for monitoring depth of anaesthesia. MLAEPs show graded changes with increasing anaesthetic concentration over the clinical concentration range. The latencies of Pa and Nb lengthen and their amplitudes reduce. These changes in features of waveform are similar with both inhaled and intravenous anaesthetics. Changes in latency of Pa and Nb waves are highly correlated to a transition from awake to loss of consciousness. MLAEPs recording may also provide information about cerebral processing of the auditory input, probably because it reflects activity in the temporal lobe/primary cortex, sites involved in sounds elaboration and in a complex mechanism of implicit (non declarative) memory processing. The coherent frequency has found to be disrupted by the anaesthetics as well as to be implicated in attentional mechanism. These results support the concept that the AEPs reflects the balance between the arousal effects of surgical stimulation and the depressant effects of anaesthetics. However, AEPs aren't a perfect measure of anaesthesia depth. They can't predict patients movements during surgery and the signal may be affected by muscle artefacts, diathermy and other electrical operating theatre interferences. In conclusion, once reliability of the AEPs recording became proved and the signal acquisition improved it is likely to became a routine feature of clinical anaesthetic practice.

The actions of volatile anaesthetics on synaptic transmission in the dentate gyrus.

PubMed Central

Richards, C D; White, A E

1975-01-01

1. The action of four volatile anaesthetics on the evoked synaptic potentials of in vitro preparations of the hippocampus were examined. 2. All four anaesthetics (ether, halothane, methoxyflurane and trichloroethylene) depressed the synaptic transmission between the perforant path and the granule cells at concentrations lower than those required to maintain anaesthesia in intact animals. 3. The population excitatory post-synaptic potential (e.p.s.p.) and massed discharge of the cortical cells (population spike) were depressed at concentrations of the anaesthetics lower than those required to depress the compound action potential of the perforant path nerve fibres. None of the anaesthetics studied increased the threshold depolarization required for granule cell discharge. Furthermore, frequency potentiation of the evoked cortical e.p.s.p.s was not impaired by any of the anaesthetics studied. 4. It is concluded that all four anaesthetics depress synaptic transmission in the dentate gyrus either by reducing the amount of transmitter released from each nerve terminal in response to an afferent volley, or by decreasing the sensitivity of the post-synaptic membrane to released transmitted or by both effects together. PMID:1202196

Time-varying bispectral analysis of visually evoked multi-channel EEG

NASA Astrophysics Data System (ADS)

Chandran, Vinod

2012-12-01

Theoretical foundations of higher order spectral analysis are revisited to examine the use of time-varying bicoherence on non-stationary signals using a classical short-time Fourier approach. A methodology is developed to apply this to evoked EEG responses where a stimulus-locked time reference is available. Short-time windowed ensembles of the response at the same offset from the reference are considered as ergodic cyclostationary processes within a non-stationary random process. Bicoherence can be estimated reliably with known levels at which it is significantly different from zero and can be tracked as a function of offset from the stimulus. When this methodology is applied to multi-channel EEG, it is possible to obtain information about phase synchronization at different regions of the brain as the neural response develops. The methodology is applied to analyze evoked EEG response to flash visual stimulii to the left and right eye separately. The EEG electrode array is segmented based on bicoherence evolution with time using the mean absolute difference as a measure of dissimilarity. Segment maps confirm the importance of the occipital region in visual processing and demonstrate a link between the frontal and occipital regions during the response. Maps are constructed using bicoherence at bifrequencies that include the alpha band frequency of 8Hz as well as 4 and 20Hz. Differences are observed between responses from the left eye and the right eye, and also between subjects. The methodology shows potential as a neurological functional imaging technique that can be further developed for diagnosis and monitoring using scalp EEG which is less invasive and less expensive than magnetic resonance imaging.

Lack of TRPM5-Expressing Microvillous Cells in Mouse Main Olfactory Epithelium Leads to Impaired Odor-Evoked Responses and Olfactory-Guided Behavior in a Challenging Chemical Environment

PubMed Central

Lemons, Kayla; Aoudé, Imad; Ogura, Tatsuya; Mbonu, Kenechukwu; Matsumoto, Ichiro; Arakawa, Hiroyuki

2017-01-01

The mammalian main olfactory epithelium (MOE) modifies its activities in response to changes in the chemical environment. This process is essential for maintaining the functions of the olfactory system and the upper airway. However, mechanisms involved in this functional maintenance, especially those occurring via paracrine regulatory pathways within the multicellular MOE, are poorly understood. Previously, a population of non-neuronal, transient receptor potential M5-expressing microvillous cells (TRPM5-MCs) was identified in the MOE, and the initial characterization of these cells showed that they are cholinergic and responsive to various xenobiotics including odorants at high concentrations. Here, we investigated the role of TRPM5-MCs in maintaining olfactory function using transcription factor Skn-1a knockout (Skn-1a-/-) mice, which lack TRPM5-MCs in the MOE. Under our standard housing conditions, Skn-1a-/- mice do not differ significantly from control mice in odor-evoked electro-olfactogram (EOG) responses and olfactory-guided behaviors, including finding buried food and preference reactions to socially and sexually relevant odors. However, after a 2-wk exposure to high-concentration odor chemicals and chitin powder, Skn-1a-/- mice exhibited a significant reduction in their odor and pheromone-evoked EOG responses. Consequently, their olfactory-guided behaviors were impaired compared with vehicle-exposed Skn-1a-/- mice. Conversely, the chemical exposure did not induce significant changes in the EOG responses and olfactory behaviors of control mice. Therefore, our physiological and behavioral results indicate that TRPM5-MCs play a protective role in maintaining the olfactory function of the MOE. PMID:28612045

Effect of intracellular photosensitized singlet oxygen production on the electrophysiological properties of cultured rat hippocampal neurons.

PubMed

Breitenbach, Thomas; Ogilby, Peter R; Lambert, John D C

2010-12-01

Whole-cell patch-clamp recordings from single cultured mammalian neurons have been used to provide insight into early membrane-dependent events that result upon the intracellular photosensitized production of singlet molecular oxygen, O(2)(a(1)Δ(g)). The singlet oxygen sensitizers used, pyropheophorbide a (PPa) and protoporphyrin IX (PpIX), locate mainly in cell membranes and mitochondria, respectively. Irradiation of these sensitizers altered both passive and dynamic electrophysiological properties of the neurons in a dose-dependent manner, though the response threshold was much lower with PPa than with PpIX. In particular, notable decreases were observed in the rising and falling rates of action potentials and, at higher light fluences, plateau potentials consistent with activation of Ca(2+) channels also developed. The data suggest that singlet oxygen production specifically influences Na(+), K(+) and Ca(2+) ionophores in the cell membrane. Upon terminating sensitizer irradiation, responses evoked by PPa stabilized immediately whereas those evoked by PpIX continued to develop. These data are consistent with a spatially-resolved sphere of intracellular singlet oxygen activity. While the response to PPa irradiation appears to be membrane specific, the response to PpIX irradiation appears to be systemic and possibly part of a cascade of apoptotic events. These results should contribute to a better understanding of membrane-dependent events pertinent to cell death mediated by singlet oxygen.

Cell surface domain specific postsynaptic currents evoked by identified GABAergic neurones in rat hippocampus in vitro

PubMed Central

Maccaferri, Gianmaria; David, J; Roberts, B; Szucs, Peter; Cottingham, Carol A; Somogyi, Peter

2000-01-01

Inhibitory postsynaptic currents (IPSCs) evoked in CA1 pyramidal cells (n = 46) by identified interneurones (n = 43) located in str. oriens were recorded in order to compare their functional properties and to determine the effect of synapse location on the apparent IPSC kinetics as recorded using somatic voltage clamp at −70 mV and nearly symmetrical [Cl−]. Five types of visualised presynaptic interneurone, oriens-lacunosum moleculare (O-LMC), basket (BC), axo-axonic (AAC), bistratified (BiC) and oriens-bistratified (O-BiC) cells, were distinguished by immunocytochemistry and/or synapse location using light and electron microscopy. Somatostatin immunoreactive O-LMCs, innervating the most distal dendritic shafts and spines, evoked the smallest amplitude (26 ± 10 pA, s.e.m., n = 8) and slowest IPSCs (10–90 % rise time, 6.2 ± 0.6 ms; decay, 20.8 ± 1.7 ms, n = 8), with no paired-pulse modulation of the second IPSC (93 ± 4 %) at 100 ms interspike interval. In contrast, parvalbumin-positive AACs evoked larger amplitude (308 ± 103 pA, n = 7) and kinetically faster (rise time, 0.8 ± 0.1 ms; decay 11.2 ± 0.9 ms, n = 7) IPSCs showing paired-pulse depression (to 68 ± 5 %, n = 6). Parvalbumin- or CCK-positive BCs (n = 9) terminating on soma/dendrites, BiCs (n = 4) and O-BiCs (n = 7) innervating dendrites evoked IPSCs with intermediate kinetic parameters. The properties of IPSCs and sensitivity to bicuculline indicated that they were mediated by GABAA receptors. In three cases, kinetically complex, multiphasic IPSCs, evoked by an action potential in the recorded basket cells, suggested that coupled interneurones, possibly through electrotonic junctions, converged on the same postsynaptic neurone. The population of O-BiCs (4 of 4 somatostatin positive) characterised in this study had horizontal dendrites restricted to str. oriens/alveus and innervated stratum radiatum and oriens. Other BiCs had radial dendrites as described earlier. The parameters of IPSCs evoked by BiCs and O-BiCs showed the largest cell to cell variation, and a single interneurone could evoke both small and slow as well as large and relatively fast IPSCs. The kinetic properties of the somatically recorded postsynaptic current are correlated with the innervated cell surface domain. A significant correlation of rise and decay times for the overall population of unitary IPSCs suggests that electrotonic filtering of distal responses is a major factor for the location and cell type specific differences of unitary IPSCs, but molecular heterogeneity of postsynaptic GABAA receptors may also contribute to the observed kinetic differences. Furthermore, domain specific differences in the short-term plasticity of the postsynaptic response indicate a differentiation of interneurones in activity-dependent responses. PMID:10747186

Comparative effects of traditional Chinese and Western migraine medicines in an animal model of nociceptive trigeminovascular activation.

PubMed

Zhao, Yonglie; Martins-Oliveira, Margarida; Akerman, Simon; Goadsby, Peter J

2018-06-01

Background Migraine is a highly prevalent and disabling disorder of the brain with limited therapeutic options, particularly for preventive treatment. There is a need to identify novel targets and test their potential efficacy in relevant preclinical migraine models. Traditional Chinese medicines have been used for millennia and may offer avenues for exploration. Methods We evaluated two traditional Chinese medicines, gastrodin and ligustrazine, and compared them to two Western approaches with propranolol and levetiracetam, one effective and one ineffective, in an established in vivo rodent model of nociceptive durovascular trigeminal activation. Results Intravenous gastrodin (30 and 100 mg/kg) significantly inhibited nociceptive dural-evoked neuronal firing in the trigeminocervical complex. Ligustrazine (10 mg/kg) and propranolol (3 mg/kg) also significantly inhibited dural-evoked trigeminocervical complex responses, although the timing of responses of ligustrazine does not match its pharmacokinetic profile. Levetiracetam had no effects on trigeminovascular responses. Conclusion Our data suggest gastrodin has potential as an anti-migraine treatment, whereas ligustrazine seems less promising. Interestingly, in line with clinical trial data, propranolol was effective and levetiracetam not. Exploration of the mechanisms and modelling effects of Chinese traditional therapies offers novel route for drug discovery in migraine.

Sex-Specific Automatic Responses to Infant Cries: TMS Reveals Greater Excitability in Females than Males in Motor Evoked Potentials

PubMed Central

Messina, Irene; Cattaneo, Luigi; Venuti, Paola; de Pisapia, Nicola; Serra, Mauro; Esposito, Gianluca; Rigo, Paola; Farneti, Alessandra; Bornstein, Marc H.

2016-01-01

Neuroimaging reveals that infant cries activate parts of the premotor cortical system. To validate this effect in a more direct way, we used event-related transcranial magnetic stimulation (TMS). Here, we investigated the presence and the time course of modulation of motor cortex excitability in young adults who listened to infant cries. Specifically, we recorded motor evoked potentials (MEPs) from the biceps brachii (BB) and interosseus dorsalis primus (ID1) muscles as produced by TMS delivered from 0 to 250 ms after sound onset in six steps of 50 ms in 10 females and 10 males. We observed an excitatory modulation of MEPs at 100 ms from the onset of infant cry specific to females and to the ID1 muscle. We regard this modulation as a response to natural cry sounds because it was attenuated to stimuli increasingly different from natural cry and absent in a separate group of females who listened to non-cry stimuli physically matched to natural infant cries. Furthermore, the 100-ms latency of this response is not compatible with a voluntary reaction to the stimulus but suggests an automatic, bottom-up audiomotor association. The brains of adult females appear to be tuned to respond to infant cries with automatic motor excitation. PMID:26779061

Acoustic Events and “Optophonic” Cochlear Responses Induced by Pulsed Near-Infrared LASER

PubMed Central

Maier, Hannes; Richter, Claus-Peter; Kral, Andrej

2012-01-01

Optical stimulation of neural tissue within the cochlea was described as a possible alternative to electrical stimulation. Most optical stimulation was performed with pulsed lasers operating with near-infrared (NIR) light and in thermal confinement. Under these conditions, the coexistence of laser-induced optoacoustic stimulation of the cochlea (“optophony”) has not been analyzed yet. This study demonstrates that pulsed 1850-nm laser light used for neural stimulation also results in sound pressure levels up to 62 dB peak-to-peak equivalent sound pressure level (SPL) in air. The sound field was confined to a small volume along the laser beam. In dry nitrogen, laser-induced acoustic events disappeared. Hydrophone measurements demonstrated pressure waves for laser fibers immersed in water. In hearing rats, laser-evoked signals were recorded from the cochlea without targeting neural tissue. The signals showed a two-domain response differing in amplitude and latency functions, as well as sensitivity to white-noise masking. The first component had characteristics of a cochlear microphonic potential, and the second component was characteristic for a compound action potential. The present data demonstrate that laser-evoked acoustic events can stimulate a hearing cochlea. Whenever optical stimulation is used, care must be taken to distinguish between such “optophony” and the true optoneural response. PMID:21278011

AT1 and AT2 Receptors in the Prelimbic Cortex Modulate the Cardiovascular Response Evoked by Acute Exposure to Restraint Stress in Rats.

PubMed

Brasil, Taíz F S; Fassini, Aline; Corrêa, Fernando M

2018-01-01

The prelimbic cortex (PL) is an important structure in the neural pathway integrating stress responses. Brain angiotensin is involved in cardiovascular control and modulation of stress responses. Blockade of angiotensin receptors has been reported to reduce stress responses. Acute restraint stress (ARS) is a stress model, which evokes sustained blood pressure increase, tachycardia, and reduction in tail temperature. We therefore hypothesized that PL locally generated angiotensin and angiotensin receptors modulate stress autonomic responses. To test this hypothesis, we microinjected an angiotensin-converting enzyme (ACE) inhibitor or angiotensin antagonists into the PL, prior to ARS. Male Wistar rats were used; guide cannulas were bilaterally implanted in the PL for microinjection of vehicle or drugs. A polyethylene catheter was introduced into the femoral artery to record cardiovascular parameters. Tail temperature was measured using a thermal camera. ARS was started 10 min after PL treatment with drugs. Pretreatment with ACE inhibitor lisinopril (0.5 nmol/100 nL) reduced the pressor response, but did not affect ARS-evoked tachycardia. At a dose of 1 nmol/100 nL, it reduced both ARS pressor and tachycardic responses. Pretreatment with candesartan, AT1 receptor antagonist reduced ARS-evoked pressor response, but not tachycardia. Pretreatment with PD123177, AT2 receptor antagonist, reduced tachycardia, but did not affect ARS pressor response. No treatment affected ARS fall in tail temperature. Results suggest involvement of PL angiotensin in the mediation of ARS cardiovascular responses, with participation of both AT1 and AT2 receptors. In conclusion, results indicate that PL AT1-receptors modulate the ARS-evoked pressor response, while AT2-receptors modulate the tachycardic component of the autonomic response.

Olfactory Nerve–Evoked, Metabotropic Glutamate Receptor–Mediated Synaptic Responses in Rat Olfactory Bulb Mitral Cells

PubMed Central

Ennis, Matthew; Zhu, Mingyan; Heinbockel, Thomas; Hayar, Abdallah

2008-01-01

The group I metabotropic glutamate receptor (mGluR) subtype, mGluR1, is highly expressed on the apical dendrites of olfactory bulb mitral cells and thus may be activated by glutamate released from olfactory nerve (ON) terminals. Previous studies have shown that mGluR1 agonists directly excite mitral cells. In the present study, we investigated the involvement of mGluR1 in ON-evoked responses in mitral cells in rat olfactory bulb slices using patch-clamp electrophysiology. In voltage-clamp recordings, the average EPSC evoked by single ON shocks or brief trains of ON stimulation (six pulses at 50 Hz) in normal physiological conditions were not significantly affected by the nonselective mGluR antagonist LY341495 (50–100 μM) or the mGluR1-specific antagonist LY367385 (100 μM); ON-evoked responses were attenuated, however, in a subset (36%) of cells. In the presence of blockers of ionotropic glutamate and GABA receptors, application of the glutamate uptake inhibitors THA (300 μM) and TBOA (100 μM) revealed large-amplitude, long-duration responses to ON stimulation, whereas responses elicited by antidromic activation of mitral/tufted cells were unaffected. Magnitudes of the ON-evoked responses elicited in the presence of THA–TBOA were dependent on stimulation intensity and frequency, and were maximal during high-frequency (50-Hz) bursts of ON spikes, which occur during odor stimulation. ON-evoked responses elicited in the presence of THA–TBOA were significantly reduced or completely blocked by LY341495 or LY367385 (100 μM). These results demonstrate that glutamate transporters tightly regulate access of synaptically evoked glutamate from ON terminals to postsynaptic mGluR1s on mitral cell apical dendrites. Taken together with other findings, the present results suggest that mGluR1s may not play a major role in phasic responses to ON input, but instead may play an important role in shaping slow oscillatory activity in mitral cells and/or activity-dependent regulation of plasticity at ON–mitral cell synapses. PMID:16394070

Effects of core body temperature on changes in spinal somatosensory-evoked potential in acute spinal cord compression injury: an experimental study in the rat.

PubMed

Jou, I M

2000-08-01

Acute spinal cord injury was induced by a clip compression model in rats to approximate spinal cord injury encountered in spinal surgery. Spinal somatosensory-evoked potential neuromonitoring was used to study the electrophysiologic change. To compare and correlate changes in evoked potential after acute compression at different core temperatures with postoperative neurologic function and histologic change, to evaluate current intraoperative neuromonitoring warning criteria for neural damage, and to confirm the protective effect of hypothermia in acute spinal cord compression injury by electrophysiologic, histologic, and clinical observation. With the increase in aggressive correction of spinal deformities, and the invasiveness of surgical instruments, the incidence of neurologic complication appears to have increased despite the availability of sensitive intraoperative neuromonitoring techniques designed to alert surgeons to impending neural damage. Many reasons have been given for the frequent failures of neuromonitoring, but the influence of temperature-a very important and frequently encountered factor-on evoked potential has not been well documented. Specifically, decrease in amplitude and elongation of latency seem not to have been sufficiently taken into account when intraoperative neuromonitoring levels were interpreted and when acceptable intraoperative warning criteria were determined. Experimental acute spinal cord injury was induced in rats by clip compression for two different intervals and at three different core temperatures. Spinal somatosensory-evoked potential, elicited by stimulating the median nerve and recorded from the cervical interspinous C2-C3, was monitored immediately before and after compression, and at 15-minute intervals for 1 hour. Spinal somatosensory-evoked potential change is almost parallel to temperature-based amplitude reduction and latency elongation. Significant neurologic damage induced by acute compression of the cervical spinal cord produced a degree of effect on the amplitude of spinal somatosensory-evoked potential in normothermic conditions that differed from the effect in moderately hypothermic conditions. Using the same electromonitoring criteria,moderately hypothermic groups showed a significantly higher false-negative rate statistically (35%) than normothermic groups (10%). Systemic cooling may protect against the detrimental effects of aggressive spinal surgical procedures. There is still not enough published information available to establish statistically and ethically acceptable intraoperative neuromonitoring warning and intervention criteria conclusively. Therefore, an urgent need exists for further investigation. Although a reduction of more than 50% in evoked potential still seems acceptable as an indicator of impending neural function loss, maintenance of more than 50% of baseline evoked potential is no guarantee of normal postoperative neural function, especially at lower than normal temperatures.

Enhancement effects of nicotine on neurogenic relaxation responses in the corpus cavernosum in rabbits: the role of nicotinic acetylcholine receptor subtypes.

PubMed

Ozturk Fincan, Gokce Sevim; Vural, Ismail Mert; Ercan, Zeynep Sevim; Sarioglu, Yusuf

2010-02-10

Nicotine acts as an agonist of nicotinic acetylcholine receptors, which belong to a superfamily of neurotransmitter-gated ion channels. We previously demonstrated that nicotine increases the electrical field stimulation (EFS)-evoked nitrergic relaxation responses via activation of nicotinic acetylcholine receptors. The aim of the present study is to investigate the subtypes of nicotinic acetylcholine receptors in rabbit corpus cavernosum. EFS-evoked relaxation responses were recorded from corpus cavernosum strips obtained from rabbits with an isometric force displacement transducers. Effects of nicotine on EFS-evoked relaxations were examined in pre-contracted tissues. Then the effect of nicotine on the EFS-evoked relaxations was examined in the presence of hexamethonium, dihydro-beta-erythroidine, mecamylamine or alpha-bungarotoxin. In our study, nicotine (3 x 10(-5), 10(-4)) transiently increased nitrergic relaxations induced by EFS in the rabbit isolated corpus cavernosum. While hexamethonium and mecamylamine near totally inhibited or abolished the neurorelaxation response to nicotine (3 x 10(-5)) on EFS, dihydro-beta-erythroidine and alpha-bungarotoxin partially inhibited these responses. These findings demonstrated that the alpha3-beta4, alpha4-beta2 and alpha7 subunits of nicotinic acetylcholine receptors play role on the nicotine-induced augmentation in EFS-evoked relaxation responses in rabbit corpus cavernosum. Copyright (c) 2009 Elsevier B.V. All rights reserved.

The effect of preterm birth on brainstem, middle latency and cortical auditory evoked responses (BMC AERs).

PubMed

Pasman, J W; Rotteveel, J J; de Graaf, R; Stegeman, D F; Visco, Y M

1992-12-01

Recent studies on the maturation of auditory brainstem evoked responses (ABRs) present conflicting results, whereas only sparse reports exist with respect to the maturation of middle latency auditory evoked responses (MLRs) and auditory cortical evoked responses (ACRs). The present study reports the effect of preterm birth on the maturation of auditory evoked responses in low risk preterm infants (27-34 weeks conceptional age). The ABRs indicate a consistent trend towards longer latencies for all individual ABR components and towards longer interpeak latencies in preterm infants. The MLR shows longer latencies for early component P0 in preterm infants. The ACRs show a remarkable difference between preterm and term infants. At 40 weeks CA the latencies of ACR components Na and P2 are significantly longer in term infants, whereas at 52 weeks CA the latencies of the same ACR components are shorter in term infants. The results support the hypothesis that retarded myelination of the central auditory pathway is partially responsible for differences found between preterm infants and term infants with respect to late ABR components and early MLR component P0. Furthermore, mild conductive hearing loss in preterm infants may also play its role. A more complex mechanism is implicated to account for the findings noted with respect to MLR component Na and ACR components Na and P2.

Quantifying the determinants of decremental response in critical ventricular tachycardia substrate.

PubMed

Beheshti, Mohammadali; Nayyar, Sachin; Magtibay, Karl; Massé, Stéphane; Porta-Sanchez, Andreu; Haldar, Shouvik; Bhaskaran, Abhishek; Vigmond, Edward; Nanthakumar, Kumaraswamy

2018-05-28

Decremental response evoked with extrastimulation (DEEP) is a useful tool for determining diastolic return path of ventricular tachycardia (VT). Though a targeted VT ablation is feasible with this approach, determinants of DEEP response have not been studied OBJECTIVES: To elucidate the effects of clinically relevant factors, specifically, the proximity of the stimulation site to the arrhythmogenic scar, stimulation wave direction, number of channels open in the scar, size of the scar and number of extra stimuli on decrement and entropy of DEEP potentials. In a 3-dimensional bi-domain simulation of human ventricular tissue (TNNP cell model), an irregular subendocardial myopathic region was generated. An irregular channel of healthy tissue with five potential entry branches was shaped into the myopathic region. A bipolar electrogram was derived from two electrodes positioned in the centre of the myopathic region. Evoked delays between far-field and local Electrogram (EGM) following an extrastimulus (S1-S2, 500-350 ms) were measured as the stimulation site, channel branches, and inexcitable tissue size were altered. Stimulation adjacent to the inexcitable tissue from the side opposite to the point-of-entry produces longest DEEP delay. The DEEP delay shortens when the stimulation point is farther away from the scar, and it decreases maximally when stimulation is done from a site beside a conduction barrier. Entropy increases with S2 when stimulation site is from farther away. An unprotected channel structure with multiple side-branch openings had shorter DEEP delay compared to a protected channel structure with a paucity of additional side-branch openings and a point-of-entry on the side opposite to the pacing source. Addition of a second shorter extrastimulus did not universally lead to higher DEEP delay CONCLUSIONS: Location and direction of the wavefront in relation to scar entry and size of scar determine the degree of evoked response while the number of extrastimuli has a small additional decremental effect. Copyright © 2018 Elsevier Ltd. All rights reserved.

Basic emotions evoked by eugenol odor differ according to the dental experience. A neurovegetative analysis.

PubMed

Robin, O; Alaoui-Ismaïli, O; Dittmar, A; Vernet-Maury, E

1999-06-01

Subjective individual experiences seem to indicate that odors may form strong connections with memories, especially those charged with emotional significance. In the dental field, this could be the case with the odorant eugenol, responsible for the typical clinging odor impregnating the dental office. The odor of eugenol could evoke memories of unpleasant dental experiences and, therefore, negative feelings such as anxiety and fear, since eugenates (cements containing eugenol) are used in potentially painful restorative dentistry. This hypothesis was tested by evaluating the emotional impact of the odor of eugenol through autonomic nervous system (ANS) analysis. The simultaneous variations of six ANS parameters (two electrodermal, two thermovascular and two cardiorespiratory), induced by the inhalation of this odorant, were recorded on volunteer subjects. Vanillin (a pleasant odorant) and propionic acid (an unpleasant one) served as controls. After the experiment, subjects were asked to rate the pleasantness versus unpleasantness of each odorant on an 11-point hedonic scale. The patterns of autonomic responses, obtained for each odorant and each subject, were transcribed into one of the six basic emotions defined by Ekman et al. (happiness, surprise, sadness, fear, anger and disgust). Results were compared between two groups of subjects divided according to their dental experience (fearful and non-fearful dental care subjects) and showed significant differences only for eugenol. This odorant was rated as pleasant by non-fearful dental subjects but unpleasant by fearful dental subjects. The evoked autonomic responses were mainly associated with positive basic emotions (happiness and surprise) in non-fearful dental subjects and with negative basic emotions (fear, anger, disgust) in fearful dental subjects. These results suggest that eugenol can be responsible for different emotional states depending on the subjects' dental experience, which seems to confirm the potential role of odors as elicitors of emotional memories. This study also supports the possible influence of the ambient odor impregnating the dental office, strengthening a negative conditioning toward dental care in some anxious patients.

An inventory and update of jealousy-evoking partner behaviours in modern society.

PubMed

Dijkstra, Pieternel; Barelds, Dick P H; Groothof, Hinke A K

2010-01-01

The goal of the present study was to identify the most important jealousy-evoking partner behaviours and to examine the extent to which these behaviours evoke jealousy. Based on the literature, a questionnaire was constructed containing 42 jealousy-evoking partner behaviours, including a partner's extra-dyadic involvement with someone else by means of modern communication devices, such as the Internet. A second study examined the extent to which undergraduates and a community sample experienced jealousy in response to these partner behaviours. Results showed that explicit unfaithful behaviours evoked most feelings of jealousy, followed by a partner's emotional or romantic involvement with someone else by means of modern communication devices. In general, older individuals responded with less jealousy in response to a partner's unfaithful and suspicious behaviours. Clinical implications are discussed. (c) 2009 John Wiley & Sons, Ltd.