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Sample records for cortical evoked potentials

  1. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    ERIC Educational Resources Information Center

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  2. [Evoked cortical somatosensory potentials in painful cervicobrachial radicular syndromes].

    PubMed

    Domzał, T; Marks, E; Miszczak, J

    1978-01-01

    The authors determined the subjective, objective and maximal pain threshold by means of electrical stimulation in two groups of subjects. Group I comprised healthy subjects, group II patients with right-sided radicular cervicobrachial pains. The method applied by the authors for objective determination of pain threshold with evoked cortical somatosensory potential differentiated both groups which suggests its practical usefulness in clinical practice and expertise. PMID:683429

  3. Mapping human brain networks with cortico-cortical evoked potentials

    PubMed Central

    Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

    2014-01-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  4. Mapping human brain networks with cortico-cortical evoked potentials.

    PubMed

    Keller, Corey J; Honey, Christopher J; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D

    2014-10-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  5. Cortical somatosensory evoked potentials in spinal cord injury patients.

    PubMed

    Berić, A

    1992-01-01

    The amplitude and latency of somatosensory evoked potentials (SEPs) in healthy subjects depend on intensity of stimulation. The effect of this parameter on SEPs in patients with neurologic disorders has not been systematically studied, although it could have a profound impact if SEPs are to be used for prognostication. We have compared the latency and amplitude of SEPs in healthy subjects and patients with spinal cord injury (SCI). Stimulation intensity was standardized at two different biologically calibrated levels. Cortical SEPs in patients with SCI showed greater decrease in latency and increase in amplitude with increased intensity of stimulation in comparison to healthy subjects. These phenomena were observed in the majority of patients with incomplete SCI who subsequently showed improvement in cortical SEPs. We observed situations in which the SEP was absent with the usual intensity of stimulation and present only with the stronger stimulation intensity. Furthermore, SEP latencies often changed dramatically with different intensities of stimulation, potentially making any calculation of central conduction velocity meaningless without precise standardization of stimulation. These findings demonstrate a necessity for a biological calibration of stimulation intensity to improve the repeatability of SEPs. We suggest the use of two different standardized intensities of stimulation for SEP studies in SCI patients, one of which should be stronger than the intensity presently recommended. PMID:1578234

  6. [The cervical somatosensory evoked potential in lesions of the cortical efferents].

    PubMed

    Strenge, H

    1990-03-01

    Cervical and cortical somatosensory evoked potentials to median nerve stimulation were analysed in 20 patients with unilateral central paresis of the arm. Neither the configuration nor the latency and amplitude measures of the neck potential did reveal any association with pathological alterations of cortical efferents or with abnormal cortically evoked responses. Thus, also in this population the evaluation of cervical potentials can be done according to the known criteria. PMID:2110891

  7. Cortico-cortical evoked potentials for sites of early versus late seizure spread in stereoelectroencephalography.

    PubMed

    Lega, Bradley; Dionisio, Sasha; Flanigan, Patrick; Bingaman, William; Najm, Imad; Nair, Dileep; Gonzalez-Martinez, Jorge

    2015-09-01

    Cortico-cortical evoked potentials offer the possibility of understanding connectivity within seizure networks to improve diagnosis and more accurately identify candidates for seizure surgery. We sought to determine if cortico-cortical evoked potentials and post-stimulation oscillatory changes differ for sites of EARLY versus LATE ictal spread. 37 patients undergoing stereoelectroencephalography were tested using a cortico-cortical evoked potential paradigm. All electrodes were classified according to the speed of ictal spread. EARLY spread sites were matched to a LATE spread site equidistant from the onset zone. Root-mean-square was used to quantify evoked responses and post-stimulation gamma band power and coherence were extracted and compared. Sites of EARLY spread exhibited significantly greater evoked responses after stimulation across all patients (t(36)=2.973, p=0.004). Stimulation elicited enhanced gamma band activity at EARLY spread sites (t(36)=2.61, p=0.03, FDR corrected); this gamma band oscillation was highly coherent with the onset zone. Cortico-cortical evoked potentials and post-stimulation changes in gamma band activity differ between sites of EARLY versus LATE ictal spread. The oscillatory changes can help visualize connectivity within the seizure network. PMID:26220373

  8. Effects of intrathecal baclofen on lumbosacral and cortical somatosensory evoked potentials.

    PubMed

    Kofler, M; Donovan, W H; Loubser, P G; Berić, A

    1992-04-01

    We analyzed lumbosacral and cortical somatosensory evoked potentials in three spinal cord injury patients undergoing evaluation of intrathecal baclofen infusion for management of spasticity. The cauda equina propagating root wave (R wave) and conus medullaris postsynaptic responses (S and P waves) were analyzed before and during baclofen infusion. Baclofen abolished the concomitantly recorded H-reflex and markedly suppressed the P wave amplitude and area. The S wave amplitude and area were suppressed to a lesser degree. In contrast, there were no significant changes in cortical somatosensory evoked potentials. PMID:1565243

  9. Evoked Potentials in Motor Cortical Local Field Potentials Reflect Task Timing and Behavioral Performance

    PubMed Central

    Confais, Joachim; Ponce-Alvarez, Adrián; Diesmann, Markus; Riehle, Alexa

    2010-01-01

    Evoked potentials (EPs) are observed in motor cortical local field potentials (LFPs) during movement execution (movement-related potentials [MRPs]) and in response to relevant visual cues (visual evoked potentials [VEPs]). Motor cortical EPs may be directionally selective, but little is known concerning their relation to other aspects of motor behavior, such as task timing and performance. We recorded LFPs in motor cortex of two monkeys during performance of a precued arm-reaching task. A time cue at the start of each trial signaled delay duration and thereby the pace of the task and the available time for movement preparation. VEPs and MRPs were strongly modulated by the delay duration, VEPs being systematically larger in short-delay trials and MRPs larger in long-delay trials. Despite these systematic modulations related to the task timing, directional selectivity was similar in short and long trials. The behavioral reaction time was positively correlated with MRP size and negatively correlated with VEP size, within sessions. In addition, the behavioral performance improved across sessions, in parallel with a slow decrease in the size of VEPs and MRPs. Our results clearly show the strong influence of the behavioral context and performance on motor cortical population activity during movement preparation and execution. PMID:20884766

  10. Evaluating long-latency auditory evoked potentials in the diagnosis of cortical hearing loss in children

    PubMed Central

    Lopez-Soto, Teresa; Postigo-Madueno, Amparo; Nunez-Abades, Pedro

    2016-01-01

    In centrally related hearing loss, there is no apparent damage in the auditory system, but the patient is unable to hear sounds. In patients with cortical hearing loss (and in the absence of communication deficit, either total or partial, as in agnosia or aphasia), some attention-related or language-based disorders may lead to a wrong diagnosis of hearing impairment. The authors present two patients (8 and 11 years old) with no anatomical damage to the ear, the absence of neurological damage or trauma, but immature cortical auditory evoked potentials. Both patients presented a clinical history of multiple diagnoses over several years. Because the most visible symptom was moderate hearing loss, the patients were recurrently referred to audiological testing, with no improvement. This report describes the use of long-latency evoked potentials to determine cases of cortical hearing loss, where hearing impairment is a consequence of underdevelopment at the central nervous system. PMID:27006780

  11. Signal type and signal-to-noise ratio interact to affect cortical auditory evoked potentials.

    PubMed

    Billings, Curtis J; Grush, Leslie D

    2016-08-01

    Use of speech signals and background noise is emerging in cortical auditory evoked potential (CAEP) studies; however, the interaction between signal type and noise level remains unclear. Two experiments determined the interaction between signal type and signal-to-noise ratio (SNR) on CAEPs. Three signals (syllable /ba/, 1000-Hz tone, and the /ba/ envelope with 1000-Hz fine structure) with varying SNRs were used in two experiments, demonstrating signal-by-SNR interactions due to both envelope and spectral characteristics. When using real-world stimuli such as speech to evoke CAEPs, temporal and spectral complexity leads to differences with traditional tonal stimuli, especially when presented in background noise. PMID:27586784

  12. Cortical brain states and corticospinal synchronization influence TMS-evoked motor potentials.

    PubMed

    Keil, Julian; Timm, Jana; Sanmiguel, Iria; Schulz, Hannah; Obleser, Jonas; Schönwiesner, Marc

    2014-02-01

    Transcranial magnetic stimulation (TMS) influences cortical processes. Recent findings indicate, however, that, in turn, the efficacy of TMS depends on the state of ongoing cortical oscillations. Whereas power and phase of electromyographic (EMG) activity recorded from the hand muscles as well as neural synchrony between cortex and hand muscles are known to influence the effect of TMS, to date, no study has shown an influence of the phase of cortical oscillations during wakefulness. We applied single-pulse TMS over the motor cortex and recorded motor-evoked potentials along with the electroencephalogram (EEG) and EMG. We correlated phase and power of ongoing EEG and EMG signals with the motor-evoked potential (MEP) amplitude. We also investigated the functional connectivity between cortical and hand muscle activity (corticomuscular coherence) with the MEP amplitude. EEG and EMG power and phase in a frequency band around 18 Hz correlated with the MEP amplitude. High beta-band (∼34 Hz) corticomuscular coherence exhibited a positive linear relationship with the MEP amplitude, indicating that strong synchrony between cortex and hand muscles at the moment when TMS is applied entails large MEPs. Improving upon previous studies, we demonstrate a clear dependence of TMS-induced motor effects on the state of ongoing EEG phase and power fluctuations. We conclude that not only the sampling of incoming information but also the susceptibility of cortical communication flow depends cyclically on neural phase. PMID:24198325

  13. 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. PMID:26688046

  14. Grating visual evoked cortical potentials in the evaluation of laser bioeffects: instrumentation

    SciTech Connect

    Randolph, D.I.; Lund, D.J.; Van Sice, C.W.; Esgandarian, G.E.

    1982-12-01

    A system was designed to permit simultaneous viewing of the ocular fundus of the rhesus monkey (Macaca mulatta), the accurate placement of laser radiation on the retina, and the stimulation of the site to produce a grating visual evoked cortical potential (VECP). A fundus camera was modified to incorporate a grating whose image was projected onto the retina at specific locations. The evoked potential could thus be obtained for any rate of alternation before, during, and after the exposure of the fovea to any one of many laser sources. An example is shown of the use of this system to monitor the grating VECP before and after exposure of the animal's fundus to a 900 nm gallium arsenide laser source for 60 sec. In this case, changes were observed in the variability of the latency of components of the VECP when compared to the prelaser exposure potentials.

  15. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus.

    PubMed

    Anzellotti, Francesca; Onofrj, Marco; Bonanni, Laura; Saracino, Antonio; Franciotti, Raffaella

    2016-01-01

    Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area. PMID:27489768

  16. Visual and noxious electrical stimulus-evoked membrane-potential responses in anterior cingulate cortical neurons.

    PubMed

    Ma, Li-Qing; Ning, Li; Wang, Zhiru; Wang, Ying-Wei

    2016-01-01

    Anterior cingulate cortex (ACC) is known to participate in numerous brain functions, such as memory storage, emotion, attention, as well as perception of acute and chronic pain. ACC-dependent brain functions often rely on ACC processing of various forms of environmental information. To understand the neural basis of ACC functions, previous studies have investigated ACC responses to environmental stimulation, particularly complex sensory stimuli as well as award and aversive stimuli, but this issue remains to be further clarified. Here, by performing whole-cell recording in vivo in anaesthetized adult rats, we examined membrane-potential (MP) responses of layer II/III ACC neurons that were evoked by a brief flash of visual stimulation and pain-related electrical stimulation delivered to hind paws. We found that ~54 and ~81 % ACC neurons exhibited excitatory MP responses, subthreshold or suprathreshold, to the visual stimulus and the electrical stimulus, respectively, with no cell showing inhibitory MP responses. We further found that the visually evoked ACC response could be greatly diminished by local lidocaine infusion in the visual thalamus, and only their temporal patterns but not amplitudes could be changed by large-scale visual cortical lesions. Our in vivo whole-cell recording data characterized in ACC neurons a visually evoked response, which was largely dependent on the visual thalamus but not visual cortex, as well as a noxious electrical stimulus-evoked response. These findings may provide potential mechanisms that are used for ACC functions on the basis of sensory information processing. PMID:27585569

  17. Cortical inhibition and habituation to evoked potentials: relevance for pathophysiology of migraine.

    PubMed

    Brighina, Filippo; Palermo, Antonio; Fierro, Brigida

    2009-04-01

    Dysfunction of neuronal cortical excitability has been supposed to play an important role in etiopathogenesis of migraine. Neurophysiological techniques like evoked potentials (EP) and in the last years non-invasive brain stimulation techniques like transcranial magnetic stimulation (TMS) and transcranial direct current stimulation gave important contribution to understanding of such issue highlighting possible mechanisms of cortical dysfunctions in migraine. EP studies showed impaired habituation to repeated sensorial stimulation and this abnormality was confirmed across all sensorial modalities, making defective habituation a neurophysiological hallmark of the disease. TMS was employed to test more directly cortical excitability in visual cortex and then also in motor cortex. Contradictory results have been reported pointing towards hyperexcitability or on the contrary to reduced preactivation of sensory cortex in migraine. Other experimental evidence speaks in favour of impairment of inhibitory circuits and analogies have been proposed between migraine and conditions of sensory deafferentation in which down-regulation of GABA circuits is considered the more relevant pathophysiological mechanism. Whatever the mechanism involved, it has been found that repeated sessions of high-frequency rTMS trains that have been shown to up-regulate inhibitory circuits could persistently normalize habituation in migraine. This could give interesting insight into pathophysiology establishing a link between cortical inhibition and habituation and opening also new treatment strategies in migraine. PMID:19209386

  18. Data to support observation of late and ultra-late latency components of cortical laser evoked potentials

    PubMed Central

    Stancak, Andrej; Cook, Stephanie; Wright, Hazel; Fallon, Nicholas

    2015-01-01

    Data are provided to document the presence of late and ultra-late latency components of cortical laser evoked potentials (LEPs) following noxious laser stimulus in Stancak et al. (2015) [3]. The latency components, labeled provisionally as N4, N5, and N6, were observed in 16 healthy human participants who were asked to fully attend their painful and non-painful sensations occurring in association with noxious laser stimulus. Individual laser evoked potential waveforms are provided in support of this observation. Data provided demonstrate the cortical sources of the late and ultra-late laser evoked potentials. The cortical sources of LEPs were reconstructed using the standardized Low Resolution Electromagnetic Tomography (sLORETA) method. PMID:26793747

  19. The color-vision approach to emotional space: cortical evoked potential data.

    PubMed

    Boucsein, W; Schaefer, F; Sokolov, E N; Schröder, C; Furedy, J J

    2001-01-01

    A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space. PMID:11666042

  20. Longitudinal Evaluation of Residual Cortical and Subcortical Motor Evoked Potentials in Spinal Cord Injured Rats.

    PubMed

    Redondo-Castro, Elena; Navarro, Xavier; García-Alías, Guillermo

    2016-05-15

    We have applied transcranial electrical stimulation to rats with spinal cord injury and selectively tested the motor evoked potentials (MEPs) conveyed by descending motor pathways with cortical and subcortical origin. MEPs were elicited by electrical stimulation to the brain and recorded on the tibialis anterior muscles. Stimulation parameters were characterized and changes in MEP responses tested in uninjured rats, in rats with mild or moderate contusion, and in animals with complete transection of the spinal cord. All injuries were located at the T8 vertebral level. Two peaks, termed N1 and N2, were obtained when changing from single pulse stimulation to trains of 9 pulses at 9 Hz. Selective injuries to the brain or spinal cord funiculi evidenced the subcortical origin of N1 and the cortical origin of N2. Animals with mild contusion showed small behavioral deficits and abolished N1 but maintained small amplitude N2 MEPs. Substantial motor deficits developed in rats with moderate contusion, and these rats had completely eliminated N1 and N2 MEPs. Animals with complete cord transection had abolished N1 and N2 and showed severe impairment of locomotion. The results indicate the reliability of MEP testing to longitudinally evaluate over time the degree of impairment of cortical and subcortical spinal pathways after spinal cord injuries of different severity. PMID:26560177

  1. The temporal relationship between the brainstem and primary cortical auditory evoked potentials.

    PubMed

    Shaw, N A

    1995-10-01

    Many methods are employed in order to define more precisely the generators of an evoked potential (EP) waveform. One technique is to compare the timing of an EP whose origin is well established with that of one whose origin is less certain. In the present article, the latency of the primary cortical auditory evoked potential (PCAEP) was compared to each of the seven subcomponents which compose the brainstem auditory evoked potential (BAEP). The data for this comparison was derived from a retrospective analysis of previous recordings of the PCAEP and BAEP. Central auditory conduction time (CACT) was calculated by subtracting the latency of the cochlear nucleus BAEP component (wave III) from that of the PCAEP. It was found that CACT in humans is 12 msec which is more than double that of central somatosensory conduction time. The interpeak latencies between BAEP waves V, VI, and VII and the PCAEP were also calculated. It was deduced that all three waves must have an origin rather more caudally within the central auditory system than is commonly supposed. In addition, it is demonstrated that the early components of the middle latency AEP (No and Na) largely reside within the time domain between the termination of the BAEP components and the PCAEP which would be consistent with their being far field reflections of midbrain and subcortical auditory activity. It is concluded that as the afferent volley ascends the central auditory pathways, it generates not a sequence of high frequency BAEP responses but rather a succession of slower post-synaptic waves. The only means of reconciling the timing of the BAEP waves with that of the PCAEP is to assume that the generation of all the BAEP components must be largely restricted to a quite confined region within the auditory nerve and the lower half of the pons. PMID:8711132

  2. 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. PMID:17715648

  3. Visual Evoked Potentials as a Readout of Cortical Function in Infants With Tuberous Sclerosis Complex.

    PubMed

    Varcin, Kandice J; Nelson, Charles A; Ko, Jordan; Sahin, Mustafa; Wu, Joyce Y; Jeste, Shafali Spurling

    2016-02-01

    Tuberous sclerosis complex is an autosomal dominant genetic disorder that confers a high risk for neurodevelopmental disorders, such as autism spectrum disorder and intellectual disability. Studies have demonstrated specific delays in visual reception skills that may predict the development of autism spectrum disorder and intellectual disability. Based on evidence for alterations in the retinogeniculate pathway in animal models of tuberous sclerosis complex, we asked whether children with tuberous sclerosis complex demonstrate alterations in early visual processing that may undermine the development of higher-level visual behaviors. Pattern-reversal visual evoked potentials were recorded in infants with tuberous sclerosis complex (n = 16) and typically developing infants (n = 18) at 12 months of age. Infants with tuberous sclerosis complex demonstrated remarkably intact visual evoked potentials even within the context of intellectual disability and epilepsy. Infants with tuberous sclerosis complex show intact visual cortical processing, suggesting that delays in visually mediated behaviors in tuberous sclerosis complex may not be rooted in early visual processing deficits. PMID:26018199

  4. Cortical Potentials Evoked by Deep Brain Stimulation in the Subthalamic Area

    PubMed Central

    Devergnas, Annaelle; Wichmann, Thomas

    2011-01-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been used since the mid-1990s as a treatment for patients with Parkinson's disease, and more recently also in other conditions, such as dystonia or obsessive compulsive disorder. Non-invasive studies of cortical evoked potentials (EPs) that follow individual STN–DBS stimuli has provided us with insights about the conduction of the DBS pulses to the cortex. Such EPs have multiple components of different latencies, making it possible to distinguish short-latency and long-latency responses (3–8 ms and 18–25 ms latency, respectively). The available evidence indicates that these short- and long-latency EPs correspond to conduction from the STN stimulation site to the cortical recording location via anti- and orthodromic pathways, respectively. In this review we survey the literature from recording studies in human patients treated with STN–DBS for Parkinson's disease and other conditions, as well as recent animal studies (including our own) that have begun to elucidate details of the pathways, frequency dependencies, and other features of EPs. In addition, we comment on the possible clinical utility of this knowledge. PMID:21625611

  5. Cortical auditory evoked potentials as an objective measure of behavioral thresholds in cochlear implant users.

    PubMed

    Visram, Anisa S; Innes-Brown, Hamish; El-Deredy, Wael; McKay, Colette M

    2015-09-01

    The aim of this study was to assess the suitability of using cortical auditory evoked potentials (CAEPs) as an objective tool for predicting behavioral hearing thresholds in cochlear implant (CI) users. Nine experienced adult CI users of Cochlear(™) devices participated. Behavioral thresholds were measured in CI users across apical, mid and basal electrodes. CAEPs were measured for the same stimuli (50 ms pulse trains of 900-pps rate) at a range of input levels across the individual's psychophysical dynamic range (DR). Amplitude growth functions using global field power (GFP) were plotted, and from this the CAEP thresholds were extrapolated and compared to the behavioral thresholds. Increased amplitude and decreased latency of the N1-P2 response was seen with increasing input level. A strong correlation was found between CAEP and behavioral thresholds (r = 0.93), implying that the cortical response may be more useful as an objective programming tool for cochlear implants than the auditory nerve response. PMID:25959269

  6. Steady-state evoked potentials to tag specific components of nociceptive cortical processing.

    PubMed

    Colon, Elisabeth; Nozaradan, Sylvie; Legrain, Valery; Mouraux, André

    2012-03-01

    Studies have shown that the periodic repetition of a stimulus induces, at certain stimulation frequencies, a sustained electro-cortical response of corresponding frequency, referred to as steady-state evoked potential (SSEP). Using infrared laser stimulation, we recently showed that SSEPs can be used to explore nociceptive cortical processing. Here, we implemented a novel approach to elicit such responses, using a periodic intra-epidermal electrical stimulation of cutaneous Aδ-nociceptors (Aδ-SSEPs). Using a wide range of frequencies (3-43 Hz), we compared the scalp topographies and temporal dynamics of these Aδ-SSEPs to the Aβ-SSEPs elicited by non-nociceptive transcutaneous electrical stimulation, as well as to the transient ERPs elicited by the onsets of the 10-s stimulation trains, applied to the left and right hand. At 3 Hz, we found that the topographies of Aβ- and Aδ-SSEPs were both maximal at the scalp vertex, and resembled closely that of the late P2 wave of transient ERPs, suggesting activity originating from the same neuronal populations. The responses also showed marked habituation, suggesting that they were mainly related to unspecific, attention-related processes. In contrast, at frequencies >3 Hz, the topographies of Aβ- and Aδ-SSEPs were markedly different. Aβ-SSEPs were maximal over the contralateral parietal region, whereas Aδ-SSEPs were maximal over midline frontal regions, thus indicating an entrainment of distinct neuronal populations. Furthermore, the responses showed no habituation, suggesting more obligatory and specific stages of sensory processing. Taken together, our results indicate that Aβ- and Aδ-SSEPs offer a unique opportunity to study the cortical representation of nociception and touch. PMID:22197788

  7. Noninvasive scalp recording of cortical auditory evoked potentials in the alert macaque monkey.

    PubMed

    Itoh, Kosuke; Nejime, Masafumi; Konoike, Naho; Nakada, Tsutomu; Nakamura, Katsuki

    2015-09-01

    Scalp-recorded evoked potentials (EP) provide researchers and clinicians with irreplaceable means for recording stimulus-related neural activities in the human brain, due to its high temporal resolution, handiness, and, perhaps more importantly, non-invasiveness. This work recorded the scalp cortical auditory EP (CAEP) in unanesthetized monkeys by using methods that are essentially identical to those applied to humans. Young adult rhesus monkeys (Macaca mulatta, 5-7 years old) were seated in a monkey chair, and their head movements were partially restricted by polystyrene blocks and tension poles placed around their head. Individual electrodes were fixated on their scalp using collodion according to the 10-20 system. Pure tone stimuli were presented while electroencephalograms were recorded from up to nineteen channels, including an electrooculogram channel. In all monkeys (n = 3), the recorded CAEP comprised a series of positive and negative deflections, labeled here as macaque P1 (mP1), macaque N1 (mN1), macaque P2 (mP2), and macaque N2 (mN2), and these transient responses to sound onset were followed by a sustained potential that continued for the duration of the sound, labeled the macaque sustained potential (mSP). mP1, mN2 and mSP were the prominent responses, and they had maximal amplitudes over frontal/central midline electrode sites, consistent with generators in auditory cortices. The study represents the first noninvasive scalp recording of CAEP in alert rhesus monkeys, to our knowledge. PMID:26031378

  8. Fabrication and testing of polyimide-based microelectrode arrays for cortical mapping of evoked potentials.

    PubMed

    Myllymaa, Sami; Myllymaa, Katja; Korhonen, Hannu; Töyräs, Juha; Jääskeläinen, Juha E; Djupsund, Kaj; Tanila, Heikki; Lappalainen, Reijo

    2009-06-15

    Modern microfabrication techniques make it possible to develop microelectrode arrays that may be utilized not only in neurophysiological research but also in the clinic, e.g. in neurosurgery and as elements of neural prostheses. The aim of this study was to test whether a flexible microelectrode array is suitable for recording cortical surface field potentials in rats. Polyimide-based microelectrode arrays were fabricated by utilizing microfabrication techniques e.g. photolithography and magnetron sputter deposition. The present microelectrode array consists of eight platinum microelectrodes (round-shaped, Ø: 200 microm), transmission lines and connector pads sandwiched between two thin layers of biocompatible polyimide. The microelectrode arrays were electrochemically characterized by impedance spectroscopy in physiological saline solution and successfully tested in vivo by conducting acute and chronic measurements of evoked potentials on the surface of rat cortex. The arrays proved excellent flexibility and mechanical strength during handling and implantation onto the surface of cortex. The excellent electrochemical characteristics and stable in vivo recordings with high spatiotemporal resolution highlight the potential of these arrays. The fabrication protocol described here allows implementation of several other neural interfaces with different layouts, material selections or target areas either for recording or stimulation purposes. PMID:19380223

  9. Cortical Auditory Evoked Potentials in (Un)aided Normal-Hearing and Hearing-Impaired Adults.

    PubMed

    Van Dun, Bram; Kania, Anna; Dillon, Harvey

    2016-02-01

    Cortical auditory evoked potentials (CAEPs) are influenced by the characteristics of the stimulus, including level and hearing aid gain. Previous studies have measured CAEPs aided and unaided in individuals with normal hearing. There is a significant difference between providing amplification to a person with normal hearing and a person with hearing loss. This study investigated this difference and the effects of stimulus signal-to-noise ratio (SNR) and audibility on the CAEP amplitude in a population with hearing loss. Twelve normal-hearing participants and 12 participants with a hearing loss participated in this study. Three speech sounds-/m/, /g/, and /t/-were presented in the free field. Unaided stimuli were presented at 55, 65, and 75 dB sound pressure level (SPL) and aided stimuli at 55 dB SPL with three different gains in steps of 10 dB. CAEPs were recorded and their amplitudes analyzed. Stimulus SNRs and audibility were determined. No significant effect of stimulus level or hearing aid gain was found in normal hearers. Conversely, a significant effect was found in hearing-impaired individuals. Audibility of the signal, which in some cases is determined by the signal level relative to threshold and in other cases by the SNR, is the dominant factor explaining changes in CAEP amplitude. CAEPs can potentially be used to assess the effects of hearing aid gain in hearing-impaired users. PMID:27587919

  10. Binocular interaction of visually evoked cortical potentials elicited by dichoptic binocular stimulation.

    PubMed

    Matsumoto, Celso Soiti; Nakagomi, Ryota; Matsumoto, Harue; Minoda, Haruka; Shinoda, Kei; Iwata, Takeshi; Mizota, Atsushi

    2014-01-01

    To analyze the interaction of cortical potentials elicited by dichoptic stimulation of the dominant and fellow eyes at different frequencies, a pair of programmed power supply units were used to drive a light emitting diode (LED) mounted in the right and left eyes of light-proof goggles to elicit the visually evoked cortical responses (VECPs). The right eye was stimulated at 11.5 Hz and the left eye at 11.0 Hz. Then the stimulation was repeated with the frequency of stimulation switched to the other eyes. The stimulus duration was 5 ms. The sampling rate was 1.0 Hz, and the duration of collection was 200 ms. The VECP of each eye was extracted separately. Individual VECPs could be recorded separately after simultaneous dichoptic stimulation of each eye. The amplitudes of the VECPs were not significantly different after stimulating the dominant eye and the fellow eye separately. The implicit times of negative peak (N-2) and the second positive peak (P-2) were shorter after stimulation of the dominant eye than after stimulation of the fellow eye, but the difference was not significant. However, the implicit time of N-2 elicited by stimulating the dominant eye was significantly shorter when the stimulation rate was 11.5 Hz. The VECPs elicited by stimulating the two eyes can be recorded separately by simultaneous dichoptic stimulation. Dichoptic simultaneous stimulation required a shorter time and may be a more sensitive method of analyzing binocular interactions compared to the classic VECPs using monocular stimulation. PMID:25194016

  11. Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex

    PubMed Central

    Grossman, Emily D.; Srinivasan, Ramesh

    2011-01-01

    Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex “control” site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks. PMID:21715670

  12. Surface temperature change, cortical evoked potential and pain behavior elicited by CO2 lasers.

    PubMed

    Yen, C T; Huang, C H; Fu, S E

    1994-01-01

    The performance of a self-designed CO2 laser stimulator, TL#2, was evaluated against a commercial product, model DE20XL of the Direct Energy Inc. (Irvine). The major items evaluated were the temperature change of the irradiated surface and the electrophysiological and behavior changes in the rat elicited by single laser pulse irradiation. Single shots of TL#2 produced a profile of surface temperature change similar to those of the DE20XL, as quantified by their maximal temperature change, rate of rise (half time to maximum) and rate of temperature drop. TL#2 and DE20XL elicited the same pain behaviors and the same pattern of cortical evoked potential in awake, behaving rats. TL#2 differed from the DE20XL in its laser beam shape and focal depth. The cross sectional energy profile of the TL#2 was a Gaussian shape, i.e., most intense at its center point, whereas that of the DE20XL with the FL20XL attachment had a shape of an inverted Gaussian, i.e., most intense in the periphery. Consequently, the peak energy of the center of the TL#2 laser beam grows rapidly with an increase in the pulse intensity. Caution must be taken not to use this machine at high intensity or for long duration less permanent damage should be produced on tested animal or human subject. In summary, TL#2 when used properly, should be a useful tool in the study of pain mechanism. PMID:7796635

  13. Cortical inhibition of laser pain and laser-evoked potentials by non-nociceptive somatosensory input.

    PubMed

    Testani, Elisa; Le Pera, Domenica; Del Percio, Claudio; Miliucci, Roberto; Brancucci, Alfredo; Pazzaglia, Costanza; De Armas, Liala; Babiloni, Claudio; Rossini, Paolo Maria; Valeriani, Massimiliano

    2015-10-01

    Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non-painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials (LEPs) due to conditioning non-painful stimuli. LEPs were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6-C7 dermatomes). Non-painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals (ISIs) after the laser pulses. LEPs obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non-painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISIs. As at these ISIs the collision between the non-painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non-painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non-painful inputs can inhibit pain at a lower level, including the spinal cord. PMID:26227011

  14. Stimulation artifact correction method for estimation of early cortico-cortical evoked potentials

    PubMed Central

    Trebaul, Lena; Rudrauf, David; Job, Anne-Sophie; Mălîia, Mihai Dragos; Popa, Irina; Barborica, Andrei; Minotti, Lorella; Mîndruţă, Ioana; Kahane, Philippe; David, Olivier

    2016-01-01

    Background Effective connectivity can be explored using direct electrical stimulations in patients suffering from drug-resistant focal epilepsies and investigated with intracranial electrodes. Responses to brief electrical pulses mimic the physiological propagation of signals and manifest as cortico-cortical evoked potentials (CCEP). The first CCEP component is believed to reflect direct connectivity with the stimulated region but the stimulation artifact, a sharp deflection occurring during a few milliseconds, frequently contaminates it. New method In order to recover the characteristics of early CCEP responses, we developed an artifact correction method based on electrical modeling of the electrode–tissue interface. The biophysically motivated artifact templates are then regressed out of the recorded data as in any classical template-matching removal artifact methods. Results Our approach is able to make the distinction between the physiological responses time-locked to the stimulation pulses and the non-physiological component. We tested the correction on simulated CCEP data in order to quantify its efficiency for different stimulation and recording parameters. We demonstrated the efficiency of the new correction method on simulations of single trial recordings for early responses contaminated with the stimulation artifact. The results highlight the importance of sampling frequency for an accurate analysis of CCEP. We then applied the approach to experimental data. Comparison with existing method The model-based template removal was compared to a correction based on the subtraction of the averaged artifact. Conclusions This new correction method of stimulation artifact will enable investigators to better analyze early CCEP components and infer direct effective connectivity in future CCEP studies. PMID:26952846

  15. Senescence of visual function as studied by visually evoked cortical potentials.

    PubMed

    Adachi-Usami, E

    1990-01-01

    Visual functions in senescence were assessed quantitatively by the pattern reversal visually evoked cortical potentials (VECP) in human subjects and animals. The results obtained in the elderly showed an elevation of contrast threshold, ie, lowered sensitivity, for higher spatial frequency, and a rise in the luminance thresholds. There was also an overall suppression in the temporal frequency curves, a sensitivity decrease for the upper half of the visual field, a blue-yellow defect and a decrease in the amplitude of accommodation. Studies of the pseudophakic eye with an intraocular lens verified that the lower transparency and yellowish changes of the crystalline lens and senile miosis do not entirely account for the depressed visual function in the elderly. The delay of P100 peak latency of the VECP in patients with juvenile Parkinson's disease after cessation of L-dopa indicated the deficiency of dopamine in these patients, which in turn was considered as a clinical model of senescence. Optic nerve fiber counts in mice showed a significant decrease in the aged group. It was considered that there is neuronal senescence other than in the eye itself. The results can be illustrated by the following daily life experience. In the evening, an elderly person would have difficulty in identifying a cat as a calico cat if the cat were atop a wall and running quickly through the visual field. It was surprising, however, that the senescence found in the visual function was not as great as that found in the other sensory organs. As further studies, investigation of the feedback mechanism from the brain to the retina and the compensatory mechanism should be made. PMID:2362377

  16. Visual Evoked Cortical Potential (VECP) Elicited by Sinusoidal Gratings Controlled by Pseudo-Random Stimulation

    PubMed Central

    Araújo, Carolina S.; Souza, Givago S.; Gomes, Bruno D.; Silveira, Luiz Carlos L.

    2013-01-01

    The contributions of contrast detection mechanisms to the visual cortical evoked potential (VECP) have been investigated studying the contrast-response and spatial frequency-response functions. Previously, the use of m-sequences for stimulus control has been almost restricted to multifocal electrophysiology stimulation and, in some aspects, it substantially differs from conventional VECPs. Single stimulation with spatial contrast temporally controlled by m-sequences has not been extensively tested or compared to multifocal techniques. Our purpose was to evaluate the influence of spatial frequency and contrast of sinusoidal gratings on the VECP elicited by pseudo-random stimulation. Nine normal subjects were stimulated by achromatic sinusoidal gratings driven by pseudo random binary m-sequence at seven spatial frequencies (0.4–10 cpd) and three stimulus sizes (4°, 8°, and 16° of visual angle). At 8° subtence, six contrast levels were used (3.12–99%). The first order kernel (K1) did not provide a consistent measurable signal across spatial frequencies and contrasts that were tested–signal was very small or absent–while the second order kernel first (K2.1) and second (K2.2) slices exhibited reliable responses for the stimulus range. The main differences between results obtained with the K2.1 and K2.2 were in the contrast gain as measured in the amplitude versus contrast and amplitude versus spatial frequency functions. The results indicated that K2.1 was dominated by M-pathway, but for some stimulus condition some P-pathway contribution could be found, while the second slice reflected the P-pathway contribution. The present work extended previous findings of the visual pathways contribution to VECP elicited by pseudorandom stimulation for a wider range of spatial frequencies. PMID:23940546

  17. 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

  18. Differential potentiation of early and late components evoked in olfactory cortex by stimulation of cortical association fibers.

    PubMed

    Stripling, Jeffrey S; Galupo, M Paz

    2008-12-30

    The present study examined in detail the development and decay of potentiation induced in vivo by repeated high-frequency stimulation of cortical association fibers (AF) in piriform cortex (PC). Male Long-Evans rats with chronically-implanted stimulating and recording electrodes were administered potentiating AF stimulation (thirty 10-pulse 100-Hz trains) on 8 consecutive days, followed by a ninth administration after an 8-day layoff. The time course of potentiation was monitored by local field potentials evoked in the PC and olfactory bulb (OB) by 0.1 Hz single-pulse AF test stimulation before, during, and following each potentiating treatment. AF test stimulation evoked two distinct components in the PC, an early component (EC) and a late component (LC). High-frequency AF stimulation produced potentiation of each component, but with very different characteristics. EC potentiation consisted of a brief augmentation during each bout of potentiating stimulation that persisted <2 min after the last high-frequency train and showed no cumulative effects following repeated induction across days. In contrast, LC potentiation developed gradually, requiring several daily potentiation treatments to reach maximum amplitude, and decayed more slowly each time it was induced. Furthermore, LC potentiation persisted in latent form for at least 8 days following its apparent decay and could be reinstated by repeated test stimulation that was without effect at the beginning of the experiment. Potentiation in the OB resembled LC potentiation in its characteristics, but with less latent potentiation. These results indicate that the potentiation reported here is distinctly different from the long-term potentiation previously demonstrated in vitro in the PC, and suggest that this potentiation represents an increase in excitability within the cortical association fiber system that can be stored in latent form and retrieved at a later time. These characteristics make this potentiation a

  19. Summary of the N1-P2 Cortical Auditory Evoked Potential to Estimate the Auditory Threshold in Adults.

    PubMed

    Lightfoot, Guy

    2016-02-01

    This article introduces the cortical auditory evoked potential (CAEP) and describes the use of the N1-P2 response complex as an objective predictor of hearing threshold in adults and older children. The generators of the CAEP are discussed together with issues of maturation, subject factors, and stimuli and recording parameters for use in the clinic. The basic methods for response identification are outlined and suggestions are made for determining the CAEP threshold. Clinical applications are introduced and the accuracy of the CAEP as an estimator of hearing threshold is given. Finally, a case study provides an example of the technique in the context of medicolegal assessment. PMID:27587918

  20. Adaptation of the cortical somatosensory evoked potential following pulsed pneumatic stimulation of the lower face in adults.

    PubMed

    Custead, Rebecca; Oh, Hyuntaek; Rosner, Austin Oder; Barlow, Steven

    2015-10-01

    Cortical adaptation to sustained sensory input is a pervasive form of short-term plasticity in neurological systems. Its role in sensory perception in health and disease, or predicting long-term plastic changes resulting from sensory training offers insight into the mechanisms of somatosensory and sensorimotor processing. A 4-channel electroencephalography (EEG) recording montage was placed bilaterally (C3-P3, C4-P4, F7-P3, F8-P4) to characterize the short-term effects of pulsed pneumatic orofacial stimulation on the cortical somatosensory evoked potential (cSEP) in twenty neurotypical adults (mean age=21±2.88 years). A servo-controlled pneumatic amplifier was used to deliver a repetitive series of pneumatic pulse trains (six 50-ms pulses, 5-second intertrain interval) through a linked pair of custom acetal homopolymer probes (aka TAC-Cells) adhered to the nonglabrous skin of the lower face proximal to the right oral angle to synchronously activate mechanoreceptive afferents in the trigeminal nerve. Blocks of pulse trains were counterbalanced among participants and delivered at two rates, 2 and 4Hz. TAC-Cell stimulation of the lower face consistently evoked a series of cSEPs at P7, N20, P28, N38, P75, N85, and P115. The spatial organization and adaptation of the evoked cSEP was dependent on stimulus pulse index (1-6 within the pulse train, p=.012), frequency of stimulus presentation (2 vs 4Hz, p<.001), component (P7-P115, p<.001), and recording montage (channels 1-4, p<.001). Early component latencies (P7-N20) were highly stable in polarity (sign) and latency, and consistent with putative far-field generators (e.g., trigeminal brainstem, ventroposteromedial thalamus). PMID:26119917

  1. Clinical Experience of Using Cortical Auditory Evoked Potentials in the Treatment of Infant Hearing Loss in Australia.

    PubMed

    Punch, Simone; Van Dun, Bram; King, Alison; Carter, Lyndal; Pearce, Wendy

    2016-02-01

    This article presents the clinical protocol that is currently being used within Australian Hearing for infant hearing aid evaluation using cortical auditory evoked potentials (CAEPs). CAEP testing is performed in the free field at two stimulus levels (65 dB sound pressure level [SPL], followed by 55 or 75 dB SPL) using three brief frequency-distinct speech sounds /m/, /ɡ/, and /t/, within a standard audiological appointment of up to 90 minutes. CAEP results are used to check or guide modifications of hearing aid fittings or to confirm unaided hearing capability. A retrospective review of 83 client files evaluated whether clinical practice aligned with the clinical protocol. It showed that most children could be assessed as part of their initial fitting program when they were identified as a priority for CAEP testing. Aided CAEPs were most commonly assessed within 8 weeks of the fitting. A survey of 32 pediatric audiologists provided information about their perception of cortical testing at Australian Hearing. The results indicated that clinical CAEP testing influenced audiologists' approach to rehabilitation and was well received by parents and that they were satisfied with the technique. Three case studies were selected to illustrate how CAEP testing can be used in a clinical environment. Overall, CAEP testing has been effectively integrated into the infant fitting program. PMID:27587921

  2. Clinical Use of Aided Cortical Auditory Evoked Potentials as a Measure of Physiological Detection or Physiological Discrimination

    PubMed Central

    Billings, Curtis J.; Papesh, Melissa A.; Penman, Tina M.; Baltzell, Lucas S.; Gallun, Frederick J.

    2012-01-01

    The clinical usefulness of aided cortical auditory evoked potentials (CAEPs) remains unclear despite several decades of research. One major contributor to this ambiguity is the wide range of variability across published studies and across individuals within a given study; some results demonstrate expected amplification effects, while others demonstrate limited or no amplification effects. Recent evidence indicates that some of the variability in amplification effects may be explained by distinguishing between experiments that focused on physiological detection of a stimulus versus those that differentiate responses to two audible signals, or physiological discrimination. Herein, we ask if either of these approaches is clinically feasible given the inherent challenges with aided CAEPs. N1 and P2 waves were elicited from 12 noise-masked normal-hearing individuals using hearing-aid-processed 1000-Hz pure tones. Stimulus levels were varied to study the effect of hearing-aid-signal/hearing-aid-noise audibility relative to the noise-masked thresholds. Results demonstrate that clinical use of aided CAEPs may be justified when determining whether audible stimuli are physiologically detectable relative to inaudible signals. However, differentiating aided CAEPs elicited from two suprathreshold stimuli (i.e., physiological discrimination) is problematic and should not be used for clinical decision making until a better understanding of the interaction between hearing-aid-processed stimuli and CAEPs can be established. PMID:23093964

  3. Cortical Auditory Evoked Potentials Reveal Changes in Audibility with Nonlinear Frequency Compression in Hearing Aids for Children: Clinical Implications.

    PubMed

    Ching, Teresa Y C; Zhang, Vicky W; Hou, Sanna; Van Buynder, Patricia

    2016-02-01

    Hearing loss in children is detected soon after birth via newborn hearing screening. Procedures for early hearing assessment and hearing aid fitting are well established, but methods for evaluating the effectiveness of amplification for young children are limited. One promising approach to validating hearing aid fittings is to measure cortical auditory evoked potentials (CAEPs). This article provides first a brief overview of reports on the use of CAEPs for evaluation of hearing aids. Second, a study that measured CAEPs to evaluate nonlinear frequency compression (NLFC) in hearing aids for 27 children (between 6.1 and 16.8 years old) who have mild to severe hearing loss is reported. There was no significant difference in aided sensation level or the detection of CAEPs for /g/ between NLFC on and off conditions. The activation of NLFC was associated with a significant increase in aided sensation levels for /t/ and /s/. It also was associated with an increase in detection of CAEPs for /t/ and /s/. The findings support the use of CAEPs for checking audibility provided by hearing aids. Based on the current data, a clinical protocol for using CAEPs to validate audibility with amplification is presented. PMID:27587920

  4. Cortical responses elicited by photovoltaic subretinal prostheses exhibit similarities to visually evoked potentials

    PubMed Central

    Mandel, Yossi; Goetz, Georges; Lavinsky, Daniel; Huie, Philip; Mathieson, Keith; Wang, Lele; Kamins, Theodore; Manivanh, Richard; Harris, James; Palanker, Daniel

    2014-01-01

    We have previously developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Here we report that implants having pixel sizes of 280, 140 and 70μm implanted in the subretinal space in rats with normal and degenerate retina elicit robust cortical responses upon stimulation with pulsed near-IR light. Implant-induced eVEP has shorter latency than visible light-induced VEP, its amplitude increases with peak irradiance and pulse duration, and decreases with frequency in the range of 2-20Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases. PMID:23778557

  5. Cortical Reorganization in Dyslexic Children after Phonological Training: Evidence from Early Evoked Potentials

    ERIC Educational Resources Information Center

    Spironelli, Chiara; Penolazzi, Barbara; Vio, Claudio; Angrilli, Alessandro

    2010-01-01

    Brain plasticity was investigated in 14 Italian children affected by developmental dyslexia after 6 months of phonological training. The means used to measure language reorganization was the recognition potential, an early wave, also called N150, elicited by automatic word recognition. This component peaks over the left temporo-occipital cortex…

  6. Dexmedetomidine infusion and somatosensory evoked potentials.

    PubMed

    Bloom, M; Beric, A; Bekker, A

    2001-10-01

    Intraoperative neurophysiologic monitoring requires information on the effects of anesthetic drugs because these drugs can directly alter evoked potentials, thus interfering with monitoring. We report on our evaluation of the effect of the recently introduced alpha2-adrenergic agonist, dexmedetomidine, on the somatosensory evoked potentials in two patients undergoing cervico-occipital fusion. Our results suggest that, although dexmedetomidine can affect the later cortical peaks of somatosensory evoked potentials (SSEPs), consistent and reproducible potentials can be recorded. PMID:11733664

  7. Cortical potentials evoked by confirming and disconfirming feedback following an auditory discrimination.

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Hillyard, S. A.; Lindsay, P. H.

    1973-01-01

    Vertex potentials elicited by visual feedback signals following an auditory intensity discrimination have been studied with eight subjects. Feedback signals which confirmed the prior sensory decision elicited small P3s, while disconfirming feedback elicited P3s that were larger. On the average, the latency of P3 was also found to increase with increasing disparity between the judgment and the feedback information. These effects were part of an overall dichotomy in wave shape following confirming vs disconfirming feedback. These findings are incorporated in a general model of the role of P3 in perceptual decision making.

  8. Reduced habituation of auditory evoked potentials indicate cortical hyper-excitability in Fragile X Syndrome.

    PubMed

    Ethridge, L E; White, S P; Mosconi, M W; Wang, J; Byerly, M J; Sweeney, J A

    2016-01-01

    Sensory hypersensitivities are common, clinically distressing features of Fragile X Syndrome (FXS). Preclinical evidence suggests this abnormality may result from synaptic hyper-excitability in sensory systems. This model predicts reduced sensory habituation to repeated stimulus presentation. Fourteen adolescents and adults with FXS and 15 age-matched controls participated in a modified auditory gating task using trains of 4 identical tones during dense array electroencephalography (EEG). Event-related potential and single trial time-frequency analyses revealed decreased habituation of the N1 event-related potential response in FXS, and increased gamma power coupled with decreases in gamma phase-locking during the early-stimulus registration period. EEG abnormalities in FXS were associated with parent reports of heightened sensory sensitivities and social communication deficits. Reduced habituation and altered gamma power and phase-locking to auditory cues demonstrated here in FXS patients parallels preclinical findings with Fmr1 KO mice. Thus, the EEG abnormalities seen in FXS patients support the model of neocortical hyper-excitability in FXS, and may provide useful translational biomarkers for evaluating novel treatment strategies targeting its neural substrate. PMID:27093069

  9. Reduced habituation of auditory evoked potentials indicate cortical hyper-excitability in Fragile X Syndrome

    PubMed Central

    Ethridge, L E; White, S P; Mosconi, M W; Wang, J; Byerly, M J; Sweeney, J A

    2016-01-01

    Sensory hypersensitivities are common, clinically distressing features of Fragile X Syndrome (FXS). Preclinical evidence suggests this abnormality may result from synaptic hyper-excitability in sensory systems. This model predicts reduced sensory habituation to repeated stimulus presentation. Fourteen adolescents and adults with FXS and 15 age-matched controls participated in a modified auditory gating task using trains of 4 identical tones during dense array electroencephalography (EEG). Event-related potential and single trial time–frequency analyses revealed decreased habituation of the N1 event-related potential response in FXS, and increased gamma power coupled with decreases in gamma phase-locking during the early-stimulus registration period. EEG abnormalities in FXS were associated with parent reports of heightened sensory sensitivities and social communication deficits. Reduced habituation and altered gamma power and phase-locking to auditory cues demonstrated here in FXS patients parallels preclinical findings with Fmr1 KO mice. Thus, the EEG abnormalities seen in FXS patients support the model of neocortical hyper-excitability in FXS, and may provide useful translational biomarkers for evaluating novel treatment strategies targeting its neural substrate. PMID:27093069

  10. Comparison of the reliability of multifocal visual evoked cortical potentials generated by pattern reversal and pattern pulse stimulation.

    PubMed

    Souza, G S; Schakelford, H B; Moura, A L A; Gomes, B D; Ventura, D F; Fitzgerald, M E C; Silveira, L C L

    2012-10-01

    This study compared the effectiveness of the multifocal visual evoked cortical potentials (mfVEP) elicited by pattern pulse stimulation with that of pattern reversal in producing reliable responses (signal-to-noise ratio >1.359). Participants were 14 healthy subjects. Visual stimulation was obtained using a 60-sector dartboard display consisting of 6 concentric rings presented in either pulse or reversal mode. Each sector, consisting of 16 checks at 99% Michelson contrast and 80 cd/m² mean luminance, was controlled by a binary m-sequence in the time domain. The signal-to-noise ratio was generally larger in the pattern reversal than in the pattern pulse mode. The number of reliable responses was similar in the central sectors for the two stimulation modes. At the periphery, pattern reversal showed a larger number of reliable responses. Pattern pulse stimuli performed similarly to pattern reversal stimuli to generate reliable waveforms in R1 and R2. The advantage of using both protocols to study mfVEP responses is their complementarity: in some patients, reliable waveforms in specific sectors may be obtained with only one of the two methods. The joint analysis of pattern reversal and pattern pulse stimuli increased the rate of reliability for central sectors by 7.14% in R1, 5.35% in R2, 4.76% in R3, 3.57% in R4, 2.97% in R5, and 1.78% in R6. From R1 to R4 the reliability to generate mfVEPs was above 70% when using both protocols. Thus, for a very high reliability and thorough examination of visual performance, it is recommended to use both stimulation protocols. PMID:22782556

  11. Comparison of the somatosensory evoked potential and the direct cortical response following severe incomplete global ischemia: selective vulnerability of the white matter conduction pathways.

    PubMed

    Lesnick, J E; Coyer, P E; Michele, J J; Welsh, F A; Simeone, F A

    1986-01-01

    Eight cats were subjected to graded hemorrhagic hypotension following bilateral carotid ligation to produce incomplete global cerebral ischemia. Three additional cats served as controls. The somatosensory evoked potential (SEP) and direct cortical response (DCR) were monitored in all animals and in each case, the cortical component of the SEP was abolished during progressive ischemia while the morphology of the DCR was well-preserved but with reduced amplitude. Determinations of adenosine triphosphate (ATP), phosphocreatine (PCr), and lactate levels in cerebral cortex and white matter were made in five experimental cats and the three controls. At the time of failure of the cortical SEP, PCr was dramatically reduced and lactate moderately elevated in the white matter while ATP remained unchanged. Cortical lactate was only mildly elevated and PCr and ATP were unchanged accounting for preservation of the DCR. In this model of global ischemia, abolition of the cortical SEP is due to a block of stimulus conduction in white matter projection pathways. A hypothesis to explain the observed metabolic changes is presented and correlation is made to clinical situations. PMID:3810728

  12. SOMATOSENSORY EVOKED POTENTIALS

    EPA Science Inventory

    Somatosensory evoked potentials (SEPs) have been used by neuroscientists for many years. The versatility of the method is attested to be the differing purposes to which it has been applied. Initially, SEPs were used to uncover basic principles of sensory processing. A casual glan...

  13. Least-squares (LS) deconvolution of a series of overlapping cortical auditory evoked potentials: a simulation and experimental study

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    Objective. To evaluate the viability of disentangling a series of overlapping ‘cortical auditory evoked potentials’ (CAEPs) elicited by different stimuli using least-squares (LS) deconvolution, and to assess the adaptation of CAEPs for different stimulus onset-asynchronies (SOAs). Approach. Optimal aperiodic stimulus sequences were designed by controlling the condition number of matrices associated with the LS deconvolution technique. First, theoretical considerations of LS deconvolution were assessed in simulations in which multiple artificial overlapping responses were recovered. Second, biological CAEPs were recorded in response to continuously repeated stimulus trains containing six different tone-bursts with frequencies 8, 4, 2, 1, 0.5, 0.25 kHz separated by SOAs jittered around 150 (120-185), 250 (220-285) and 650 (620-685) ms. The control condition had a fixed SOA of 1175 ms. In a second condition, using the same SOAs, trains of six stimuli were separated by a silence gap of 1600 ms. Twenty-four adults with normal hearing (<20 dB HL) were assessed. Main results. Results showed disentangling of a series of overlapping responses using LS deconvolution on simulated waveforms as well as on real EEG data. The use of rapid presentation and LS deconvolution did not however, allow the recovered CAEPs to have a higher signal-to-noise ratio than for slowly presented stimuli. The LS deconvolution technique enables the analysis of a series of overlapping responses in EEG. Significance. LS deconvolution is a useful technique for the study of adaptation mechanisms of CAEPs for closely spaced stimuli whose characteristics change from stimulus to stimulus. High-rate presentation is necessary to develop an understanding of how the auditory system encodes natural speech or other intrinsically high-rate stimuli.

  14. Vestibular receptors contribute to cortical auditory evoked potentials☆

    PubMed Central

    Todd, Neil P.M.; Paillard, Aurore C.; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G.

    2014-01-01

    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. PMID:24321822

  15. From evoked potentials to cortical currents: Resolving V1 and V2 components using retinotopy constrained source estimation without fMRI.

    PubMed

    Inverso, Samuel A; Goh, Xin-Lin; Henriksson, Linda; Vanni, Simo; James, Andrew C

    2016-05-01

    Despite evoked potentials' (EP) ubiquity in research and clinical medicine, insights are limited to gross brain dynamics as it remains challenging to map surface potentials to their sources in specific cortical regions. Multiple sources cancellation due to cortical folding and cross-talk obscures close sources, e.g. between visual areas V1 and V2. Recently retinotopic functional magnetic resonance imaging (fMRI) responses were used to constrain source locations to assist separating close sources and to determine cortical current generators. However, an fMRI is largely infeasible for routine EP investigation. We developed a novel method that replaces the fMRI derived retinotopic layout (RL) by an approach where the retinotopy and current estimates are generated from EEG or MEG signals and a standard clinical T1-weighted anatomical MRI. Using the EEG-RL, sources were localized to within 2 mm of the fMRI-RL constrained localized sources. The EEG-RL also produced V1 and V2 current waveforms that closely matched the fMRI-RL's (n = 2) r(1,198)  = 0.99, P < 0.0001. Applying the method to subjects without fMRI (n = 4) demonstrates it generates waveforms that agree closely with the literature. Our advance allows investigators with their current EEG or MEG systems to create a library of brain models tuned to individual subjects' cortical folding in retinotopic maps, and should be applicable to auditory and somatosensory maps. The novel method developed expands EP's ability to study specific brain areas, revitalizing this well-worn technique. Hum Brain Mapp 37:1696-1709, 2016. © 2016 Wiley Periodicals, Inc. PMID:26870938

  16. Comparison of electrically evoked cortical potential thresholds generated with subretinal or suprachoroidal placement of a microelectrode array in the rabbit

    NASA Astrophysics Data System (ADS)

    Yamauchi, Yasuyuki; Franco, Luisa M.; Jackson, Douglas J.; Naber, John F.; Ofer Ziv, R.; Rizzo, Joseph F., III; Kaplan, Henry J.; Enzmann, Volker

    2005-03-01

    The aim of the study was to directly compare the threshold electrical charge density of the retina (retinal threshold) in rabbits for the generation of electrical evoked potentials (EEP) by delivering electrical stimulation with a custom-made microelectrode array (MEA) implanted into either the subretinal or suprachoroidal space. Nine eyes of seven Dutch-belted rabbits were studied. The electroretinogram (ERG), visual evoked potentials (VEP) and EEP were recorded. Electrodes for the VEP and EEP were placed on the dura mater overlying the visual cortex. The EEP was recorded following electrical stimulation of the MEA placed either subretinally beneath the visual streak of the retina or in the suprachoroidal space in the rabbit eye. An ab externo approach was used for placement of the MEA. Liquid perfluorodecaline (PFCL; 0.4 ml) was placed within the vitreous cavity to flatten the neurosensory retina on the MEA after subretinal implantation. The retinal threshold for generation of an EEP was determined for each MEA placement by three consecutive measurements consisting of 100 computer-averaged recordings. Animals were sacrificed at the conclusion of the experiment and the eyes were enucleated for histological examination. The retinal threshold to generate an EEP was 9 ± 7 nC (0.023 ± 0.016 mC cm-2) within the subretinal space and 150 ± 122 nC (0.375 ± 0.306 mC cm-2) within the suprachoroidal space. Histology showed disruption of the outer retina with subretinal but not suprachoroidal placement. The retinal threshold to elicit an EEP is significantly lower with subretinal placement of the MEA compared to suprachoroidal placement (P < 0.05). The retinal threshold charge density with a subretinal MEA is well below the published charge limit of 1 mC cm-2, which is the level below which chronic stimulation of the retina is considered necessary to avoid tissue damage (Shannon 1992 IEEE Trans. Biomed. Eng. 39 424-6). Supported in part by The Charles D Kelman, MD

  17. [Age changes in early somatosensory evoked potentials].

    PubMed

    Strenge, H

    1986-06-01

    There are characteristic age-related changes in the cervical and early cortical somatosensory potentials evoked by electrical stimulation of the median nerve. At an age of 40 to 50 years the latencies of the potential components and the transit times start increasing progressively. Moreover, there is an attenuation of the cervical and an enhancement of the cortical components with age. Considering the presumed neuronal basis of the bioelectric phenomena the changes are discussed in connection with aging processes of the spinal ganglion cells, cortical pyramidal cells and the locus coeruleus. PMID:3017682

  18. The Effect of Short-Term Auditory Training on Speech in Noise Perception and Cortical Auditory Evoked Potentials in Adults with Cochlear Implants.

    PubMed

    Barlow, Nathan; Purdy, Suzanne C; Sharma, Mridula; Giles, Ellen; Narne, Vijay

    2016-02-01

    This study investigated whether a short intensive psychophysical auditory training program is associated with speech perception benefits and changes in cortical auditory evoked potentials (CAEPs) in adult cochlear implant (CI) users. Ten adult implant recipients trained approximately 7 hours on psychophysical tasks (Gap-in-Noise Detection, Frequency Discrimination, Spectral Rippled Noise [SRN], Iterated Rippled Noise, Temporal Modulation). Speech performance was assessed before and after training using Lexical Neighborhood Test (LNT) words in quiet and in eight-speaker babble. CAEPs evoked by a natural speech stimulus /baba/ with varying syllable stress were assessed pre- and post-training, in quiet and in noise. SRN psychophysical thresholds showed a significant improvement (78% on average) over the training period, but performance on other psychophysical tasks did not change. LNT scores in noise improved significantly post-training by 11% on average compared with three pretraining baseline measures. N1P2 amplitude changed post-training for /baba/ in quiet (p = 0.005, visit 3 pretraining versus visit 4 post-training). CAEP changes did not correlate with behavioral measures. CI recipients' clinical records indicated a plateau in speech perception performance prior to participation in the study. A short period of intensive psychophysical training produced small but significant gains in speech perception in noise and spectral discrimination ability. There remain questions about the most appropriate type of training and the duration or dosage of training that provides the most robust outcomes for adults with CIs. PMID:27587925

  19. Cortical Responsiveness to Nociceptive Stimuli in Patients with Chronic Disorders of Consciousness: Do C-Fiber Laser Evoked Potentials Have a Role?

    PubMed Central

    Naro, Antonino; Russo, Margherita; Leo, Antonino; Rifici, Carmela; Pollicino, Patrizia; Bramanti, Placido; Calabrò, Rocco Salvatore

    2015-01-01

    It has been shown that the presence of Aδ-fiber laser evoked potentials (Aδ-LEP) in patients suffering from chronic disorders of consciousness (DOC), such as vegetative state (VS) and minimally conscious state (MCS), may be the expression of a residual cortical pain arousal. Interestingly, the study of C-fiber LEP (C-LEP) could be useful in the assessment of cortical pain arousal in the DOC individuals who lack of Aδ-LEP. To this end, we enrolled 38 DOC patients following post-anoxic or post-traumatic brain injury, who met the international criteria for VS and MCS diagnosis. Each subject was clinically evaluated, through the coma recovery scale-revised (CRS-R) and the nociceptive coma scale-revised (NCS-R), and electrophysiologically tested by means of a solid-state laser for Aδ-LEP and C-LEP. VS individuals showed increased latencies and reduced amplitudes of both the Aδ-LEP and C-LEP components in comparison to MCS patients. Although nearly all of the patients had both the LEP components, some VS individuals showed only the C-LEP ones. Notably, such patients had a similar NCS-R score to those having both the LEP components. Hence, we could hypothesize that C-LEP generators may be rearranged or partially spared in order to still guarantee cortical pain arousal when Aδ-LEP generators are damaged. Therefore, the residual presence of C-LEP should be assessed when Aδ-LEP are missing, since a potential pain experience should be still present in some patients, so to properly initiate, or adapt, the most appropriate pain treatment. PMID:26674634

  20. Explaining the high voice superiority effect in polyphonic music: evidence from cortical evoked potentials and peripheral auditory models.

    PubMed

    Trainor, Laurel J; Marie, Céline; Bruce, Ian C; Bidelman, Gavin M

    2014-02-01

    Natural auditory environments contain multiple simultaneously-sounding objects and the auditory system must parse the incoming complex sound wave they collectively create into parts that represent each of these individual objects. Music often similarly requires processing of more than one voice or stream at the same time, and behavioral studies demonstrate that human listeners show a systematic perceptual bias in processing the highest voice in multi-voiced music. Here, we review studies utilizing event-related brain potentials (ERPs), which support the notions that (1) separate memory traces are formed for two simultaneous voices (even without conscious awareness) in auditory cortex and (2) adults show more robust encoding (i.e., larger ERP responses) to deviant pitches in the higher than in the lower voice, indicating better encoding of the former. Furthermore, infants also show this high-voice superiority effect, suggesting that the perceptual dominance observed across studies might result from neurophysiological characteristics of the peripheral auditory system. Although musically untrained adults show smaller responses in general than musically trained adults, both groups similarly show a more robust cortical representation of the higher than of the lower voice. Finally, years of experience playing a bass-range instrument reduces but does not reverse the high voice superiority effect, indicating that although it can be modified, it is not highly neuroplastic. Results of new modeling experiments examined the possibility that characteristics of middle-ear filtering and cochlear dynamics (e.g., suppression) reflected in auditory nerve firing patterns might account for the higher-voice superiority effect. Simulations show that both place and temporal AN coding schemes well-predict a high-voice superiority across a wide range of interval spacings and registers. Collectively, we infer an innate, peripheral origin for the higher-voice superiority observed in human

  1. Single-sweep spectral analysis of contact heat evoked potentials: a novel approach to identify altered cortical processing after morphine treatment

    PubMed Central

    Hansen, Tine M; Graversen, Carina; Frøkjær, Jens B; Olesen, Anne E; Valeriani, Massimiliano; Drewes, Asbjørn M

    2015-01-01

    Aims The cortical response to nociceptive thermal stimuli recorded as contact heat evoked potentials (CHEPs) may be altered by morphine. However, previous studies have averaged CHEPs over multiple stimuli, which are confounded by jitter between sweeps. Thus, the aim was to assess single-sweep characteristics to identify alterations induced by morphine. Methods In a crossover study 15 single-sweep CHEPs were analyzed from 62 electroencephalography electrodes in 26 healthy volunteers before and after administration of morphine or placebo. Each sweep was decomposed by a continuous wavelet transform to obtain normalized spectral indices in the delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–32 Hz) and gamma (32–80 Hz) bands. The average distribution over all sweeps and channels was calculated for the four recordings for each volunteer, and the two recordings before treatments were assessed for reproducibility. Baseline corrected spectral indices after morphine and placebo treatments were compared to identify alterations induced by morphine. Results Reproducibility between baseline CHEPs was demonstrated. As compared with placebo, morphine decreased the spectral indices in the delta and theta bands by 13% (P = 0.04) and 9% (P = 0.007), while the beta and gamma bands were increased by 10% (P = 0.006) and 24% (P = 0.04). Conclusion The decreases in the delta and theta band are suggested to represent a decrease in the pain specific morphology of the CHEPs, which indicates a diminished pain response after morphine administration. Hence, assessment of spectral indices in single-sweep CHEPs can be used to study cortical mechanisms induced by morphine treatment. PMID:25556985

  2. Detection Rates of Cortical Auditory Evoked Potentials at Different Sensation Levels in Infants with Sensory/Neural Hearing Loss and Auditory Neuropathy Spectrum Disorder.

    PubMed

    Gardner-Berry, Kirsty; Chang, Hsiuwen; Ching, Teresa Y C; Hou, Sanna

    2016-02-01

    With the introduction of newborn hearing screening, infants are being diagnosed with hearing loss during the first few months of life. For infants with a sensory/neural hearing loss (SNHL), the audiogram can be estimated objectively using auditory brainstem response (ABR) testing and hearing aids prescribed accordingly. However, for infants with auditory neuropathy spectrum disorder (ANSD) due to the abnormal/absent ABR waveforms, alternative measures of auditory function are needed to assess the need for amplification and evaluate whether aided benefit has been achieved. Cortical auditory evoked potentials (CAEPs) are used to assess aided benefit in infants with hearing loss; however, there is insufficient information regarding the relationship between stimulus audibility and CAEP detection rates. It is also not clear whether CAEP detection rates differ between infants with SNHL and infants with ANSD. This study involved retrospective collection of CAEP, hearing threshold, and hearing aid gain data to investigate the relationship between stimulus audibility and CAEP detection rates. The results demonstrate that increases in stimulus audibility result in an increase in detection rate. For the same range of sensation levels, there was no difference in the detection rates between infants with SNHL and ANSD. PMID:27587922

  3. [The repeat reliability of somatosensory evoked potentials].

    PubMed

    Strenge, H

    1989-09-01

    The test-immediate-retest reliability of latency and amplitude values of cervical and cortical somatosensory evoked potentials (SEP) to median nerve stimulation was assessed in 86 normal subjects aged 15 to 71 years. In addition to the stability of data between repeat trials within one test session the standard errors of measurement and the interpretable differences for SEP measures were calculated according to measurement theory. The study revealed retest correlations rtt greater than 0.80 for all latency measures of the cervical and cortical SEPs and all cortical amplitude parameters. The highest stability was found for the latency measures of the cervical components P10, N11, N13, the cortical components P16 and N20 and for the amplitude N20/P25. PMID:2507277

  4. Maturation of cortical auditory evoked potentials (CAEPs) to speech recorded from frontocentral and temporal sites: three months to eight years of age

    PubMed Central

    Yu, Yan H.; Wagner, Monica

    2014-01-01

    The goal of the current analysis was to examine the maturation of cortical auditory evoked potentials (CAEPs) from three months of age to eight years of age. The superior frontal positive-negative-positive sequence (P1, N2, P2) and the temporal site, negative-positive-negative sequence (possibly, Na, Ta, Tb of the T-complex) were examined. Event-related potentials were recorded from 63 scalp sites to a 250- ms vowel. Amplitude and latency of peaks were measured at left and right frontal sites (near Fz) and at left and right temporal sites (T7 and T8). In addition the largest peak (typically corresponding to P1) was selected from global field power (GFP). The results revealed a large positive peak (P1) easily identified at frontal sites across all ages. The N2 emerged after 6 months of age and the following P2 between 8 and 30 months of age. The latencies of these peaks decreased exponentially with the most rapid decrease observed for P1. For amplitude, only P1 showed a clear relationship with age, becoming more positive in a somewhat linear fashion. At the temporal sites only a negative peak, which might be Na, was clearly observed at both left and right sites in children older than 14 months and peaking between 100 and 200 ms. P1 measures at frontal sites and Na peak latencies were moderately correlated. The temporal negative peak latency showed a different maturational timecourse (linear in nature) than the P1 peak, suggesting at least partial independence. Distinct Ta (positive) and Tb (negative) peaks, following Na and peaking between 120 and 220 ms were not consistently found in most age groups of children, except Ta which was present in 7 year olds. Future research, which includes manipulation of stimulus factors, and use of modeling techniques will be needed to explain the apparent, protracted maturation of the temporal site measures in the current study. PMID:25219893

  5. Maturation of cortical auditory evoked potentials (CAEPs) to speech recorded from frontocentral and temporal sites: three months to eight years of age.

    PubMed

    Shafer, Valerie L; Yu, Yan H; Wagner, Monica

    2015-02-01

    The goal of the current analysis was to examine the maturation of cortical auditory evoked potentials (CAEPs) from three months of age to eight years of age. The superior frontal positive-negative-positive sequence (P1, N2, P2) and the temporal site, negative-positive-negative sequence (possibly, Na, Ta, Tb of the T-complex) were examined. Event-related potentials were recorded from 63 scalp sites to a 250-ms vowel. Amplitude and latency of peaks were measured at left and right frontal sites (near Fz) and at left and right temporal sites (T7 and T8). In addition, the largest peak (typically corresponding to P1) was selected from global field power (GFP). The results revealed a large positive peak (P1) easily identified at frontal sites across all ages. The N2 emerged after 6 months of age and the following P2 between 8 and 30 months of age. The latencies of these peaks decreased exponentially with the most rapid decrease observed for P1. For amplitude, only P1 showed a clear relationship with age, becoming more positive in a somewhat linear fashion. At the temporal sites only a negative peak, which might be Na, was clearly observed at both left and right sites in children older than 14 months and peaking between 100 and 200 ms. P1 measures at frontal sites and Na peak latencies were moderately correlated. The temporal negative peak latency showed a different maturational timecourse (linear in nature) than the P1 peak, suggesting at least partial independence. Distinct Ta (positive) and Tb (negative) peaks, following Na and peaking between 120 and 220 ms were not consistently found in most age groups of children, except Ta which was present in 7 year olds. Future research, which includes manipulation of stimulus factors, and use of modeling techniques will be needed to explain the apparent, protracted maturation of the temporal site measures in the current study. PMID:25219893

  6. Temporal progression of evoked field potentials in neocortical slices after unilateral hypoxia-ischemia in perinatal rats: Correlation with cortical epileptogenesis.

    PubMed

    Kadam, S D; Dudek, F E

    2016-03-01

    Infarcts of the neonatal cerebral cortex can lead to progressive epilepsy, which is characterized by time-dependent increases in seizure frequency after the infarct and by shifts in seizure-onset zones from focal to multi-focal. Using a rat model of unilateral perinatal hypoxia-ischemia (PHI), where long-term seizure monitoring had previously demonstrated progressive epilepsy, evoked field potentials (EFPs) were recorded in layers II/III of coronal neocortical slices to analyze the underlying time-dependent, network-level alterations ipsilateral vs. contralateral to the infarct. At 3weeks after PHI, EFPs ipsilateral to the infarct were normal in artificial cerebrospinal fluid (ACSF); however, after blocking GABAA receptors with bicuculline methiodide (BMI, 30μM), the slices with an infarct were more hyperexcitable than slices without an infarct. At 3weeks, contralateral PHI slices had responses indistinguishable from controls. Six months after PHI in normal ACSF, both ipsi- and contralateral slices from rats with cortical infarcts showed prolonged afterdischarges, which were only slightly augmented in BMI. These data suggest that the early changes after PHI are localized to the ipsilateral infarcted cortex and masked by GABA-mediated inhibition; however, after 6months, progressive epileptogenesis results in generation of robust bilateral hyperexcitability. Because these afterdischarges were only slightly prolonged by BMI, a time-dependent reduction of GABAergic transmission is hypothesized to contribute to the pronounced hyperexcitability at 6months. These changes in the EFPs coincide with the seizure semiology of the epilepsy and therefore offer an opportunity to study the mechanisms underlying this form of progressive pediatric epilepsy. PMID:26724579

  7. [Somatosensory evoked potentials in moderate hyperthermia].

    PubMed

    Strenge, H

    1991-09-01

    The effects of moderate whole-body hyperthermia on the cervical and cortical somatosensory evoked potentials (SEP) were studied in healthy male subjects, aged 22-32 years. They were immersed in hot water and heated to a median rectal temperature of 39.0 degrees C. Serial SEPs to median nerve stimulation were recorded during cooling at intervals of 0.1 degrees C. The general wave form and the amplitudes did not systematically change. For a 1 degrees C drop there was a median latency increase of 2.6-3.7% in cervical and 1.5-7.4% in cortical SEP components. In individual cases significant latency delays of cervical N13 and cortical N20 could already be observed at differences of 0.2 degrees and 0.5 degrees respectively. All other components showed significant latency changes at temperature intervals of 0.6 to 0.8 degrees C. PMID:1765026

  8. [Cortical responses evoked by vibrotactile sensations in deaf children].

    PubMed

    Quaranta, A; Cipriani, D; Mininni, F

    1980-05-30

    Vibrotactile evoked responses (VER) to 250 and 500 Hz presented respectively at 50 and 70 dB HL by BC vibrator placed on right thumb, were recorded in 20 children (10 with pathological EEG) with severe sensorineural hearing loss, or deaf since birth, both to control accuracy of cortical responses to high intensity auditory stimuli and to diagnose central non auditory pathways lesions. The results have shown that: VER are present in subjects with severe sensorineural hearing loss or deaf; in children with auditory lesions VER have parameters different from auditory evoked response (AER); VER recording is not related both to the presence of auditory lesions and to neurological pathology. PMID:7448007

  9. Reduced variability of ongoing and evoked cortical activity leads to improved behavioral performance.

    PubMed

    Ledberg, Anders; Montagnini, Anna; Coppola, Richard; Bressler, Steven L

    2012-01-01

    Sensory responses of the brain are known to be highly variable, but the origin and functional relevance of this variability have long remained enigmatic. Using the variable foreperiod of a visual discrimination task to assess variability in the primate cerebral cortex, we report that visual evoked response variability is not only tied to variability in ongoing cortical activity, but also predicts mean response time. We used cortical local field potentials, simultaneously recorded from widespread cortical areas, to gauge both ongoing and visually evoked activity. Trial-to-trial variability of sensory evoked responses was strongly modulated by foreperiod duration and correlated both with the cortical variability before stimulus onset as well as with response times. In a separate set of experiments we probed the relation between small saccadic eye movements, foreperiod duration and manual response times. The rate of eye movements was modulated by foreperiod duration and eye position variability was positively correlated with response times. Our results indicate that when the time of a sensory stimulus is predictable, reduction in cortical variability before the stimulus can improve normal behavioral function that depends on the stimulus. PMID:22937021

  10. [Auditory evoked potentials: basics and clinical applications].

    PubMed

    Radeloff, A; Cebulla, M; Shehata-Dieler, W

    2014-09-01

    Auditory evoked potentials (AEPs) are elicited at various levels of the auditory system following acoustic stimulation. Electrocochleography is a technique for recording AEPs of the inner ear. The recording is performed by means of a needle electrode placed on the promontory or non-invasive with tympanic membrane or ear canal electrodes. Clinically, electrocochleography is used for the diagnosis of auditory neuropathy spectrum disorder (ANSD) and endolymphatic hydrops. According to their latencies, AEPs of the central auditory pathway are subdivided into early, middle and late (cortical) AEPs. These AEPs are recorded via surface scalp electrodes. Normally, the larger EEG masks AEPs. For unmasking the AEP, several techniques are applied. Early AEPs or auditory brainstem responses (ABR) are the most widely used AEPs for functional evaluation of the auditory pathway. In contrast to otoacoustic emissions, early AEPs can detect ANSD. Thus, they are more suitable for hearing screening in newborns. For this purpose automated procedures are implemented. PMID:25152975

  11. Dynamics of multistable states during ongoing and evoked cortical activity.

    PubMed

    Mazzucato, Luca; Fontanini, Alfredo; La Camera, Giancarlo

    2015-05-27

    Single-trial analyses of ensemble activity in alert animals demonstrate that cortical circuits dynamics evolve through temporal sequences of metastable states. Metastability has been studied for its potential role in sensory coding, memory, and decision-making. Yet, very little is known about the network mechanisms responsible for its genesis. It is often assumed that the onset of state sequences is triggered by an external stimulus. Here we show that state sequences can be observed also in the absence of overt sensory stimulation. Analysis of multielectrode recordings from the gustatory cortex of alert rats revealed ongoing sequences of states, where single neurons spontaneously attain several firing rates across different states. This single-neuron multistability represents a challenge to existing spiking network models, where typically each neuron is at most bistable. We present a recurrent spiking network model that accounts for both the spontaneous generation of state sequences and the multistability in single-neuron firing rates. Each state results from the activation of neural clusters with potentiated intracluster connections, with the firing rate in each cluster depending on the number of active clusters. Simulations show that the model's ensemble activity hops among the different states, reproducing the ongoing dynamics observed in the data. When probed with external stimuli, the model predicts the quenching of single-neuron multistability into bistability and the reduction of trial-by-trial variability. Both predictions were confirmed in the data. Together, these results provide a theoretical framework that captures both ongoing and evoked network dynamics in a single mechanistic model. PMID:26019337

  12. Dynamics of Multistable States during Ongoing and Evoked Cortical Activity

    PubMed Central

    Mazzucato, Luca

    2015-01-01

    Single-trial analyses of ensemble activity in alert animals demonstrate that cortical circuits dynamics evolve through temporal sequences of metastable states. Metastability has been studied for its potential role in sensory coding, memory, and decision-making. Yet, very little is known about the network mechanisms responsible for its genesis. It is often assumed that the onset of state sequences is triggered by an external stimulus. Here we show that state sequences can be observed also in the absence of overt sensory stimulation. Analysis of multielectrode recordings from the gustatory cortex of alert rats revealed ongoing sequences of states, where single neurons spontaneously attain several firing rates across different states. This single-neuron multistability represents a challenge to existing spiking network models, where typically each neuron is at most bistable. We present a recurrent spiking network model that accounts for both the spontaneous generation of state sequences and the multistability in single-neuron firing rates. Each state results from the activation of neural clusters with potentiated intracluster connections, with the firing rate in each cluster depending on the number of active clusters. Simulations show that the model's ensemble activity hops among the different states, reproducing the ongoing dynamics observed in the data. When probed with external stimuli, the model predicts the quenching of single-neuron multistability into bistability and the reduction of trial-by-trial variability. Both predictions were confirmed in the data. Together, these results provide a theoretical framework that captures both ongoing and evoked network dynamics in a single mechanistic model. PMID:26019337

  13. Do unresponsive wakefulness syndrome patients feel pain? Role of laser-evoked potential-induced gamma-band oscillations in detecting cortical pain processing.

    PubMed

    Naro, A; Leo, A; Cannavò, A; Buda, A; Bramanti, P; Calabrò, R S

    2016-03-11

    It has been proposed that a neural signature of aware pain perception could be represented by the modulation of gamma-band oscillation (GBO) power induced by nociceptive repetitive laser stimulation (RLS). The aim of our study was to correlate the RLS-induced GBO modulation with the Nociception Coma Scale-Revised (NCS-R) scores (a validated scale assessing possible aware pain perception in patients with chronic disorders of consciousness), in an attempt to differentiate unresponsive wakefulness syndrome (UWS) patients from minimally conscious state (MCS) ones (both of them are awake but exhibit no or limited and fluctuant behavioral signs of awareness and mentation, and low and high NCS-R scores, respectively). In addition, we attempted to identify those among UWS patients who probably experienced pain at covert level (i.e. being aware but unable to show pain-related purposeful behaviors, which are those sustained, reproducible, and voluntary behavioral responses to nociceptive stimuli). Notably, the possibility of clearly differentiating UWS from MCS patients has outmost consequences concerning prognosis (worse in UWS) and adequate pain treatment. RLS consisted in 80 trains of three laser stimuli (delivered at 1Hz), at four different energies, able to evoke Aδ-fiber related laser evoked potentials. After each train, we assessed the NCS-R score. EEG was divided into epochs according to the laser trains, and the obtained epochs were classified in four categories according to the NCS-R score magnitude. We quantified the GBO absolute power for each category. RLS protocol induced a strongly correlated increase in GBO power and NCS-R score (the higher the laser stimulation intensity, the higher the NCS-R, independently of stimulus repetition) in all the MCS patients, thus confirming the presence of aware pain processing. Nonetheless, such findings were present even in five UWS individuals. This could suggest the presence of covert pain processing in such subjects

  14. Perceptual expectation evokes category-selective cortical activity.

    PubMed

    Esterman, Michael; Yantis, Steven

    2010-05-01

    Selective visual attention directed to a location (even in the absence of a stimulus) increases activity in the corresponding regions of visual cortex and enhances the speed and accuracy of target perception. We further explored top-down influences on perceptual representations by manipulating observers' expectations about the category of an upcoming target. Observers viewed a display in which an object (either a face or a house) gradually emerged from a state of phase-scrambled noise; a cue established expectation about the object category. Observers were faster to categorize faces (gender discrimination) or houses (structural discrimination) when the category of the partially scrambled object matched their expectation. Functional magnetic resonance imaging revealed that this expectation was associated with anticipatory increases in category-specific visual cortical activity, even in the absence of object- or category-specific visual information. Expecting a face evoked increased activity in face-selective cortical regions in the fusiform gyrus and superior temporal sulcus. Conversely, expecting a house increased activity in parahippocampal gyrus. These results suggest that visual anticipation facilitates subsequent perception by recruiting, in advance, the same cortical mechanisms as those involved in perception. PMID:19759124

  15. USE OF SENSORY EVOKED POTENTIALS IN TOXICOLOGY

    EPA Science Inventory

    The rationale for studying sensory systems as an integral part of neurotoxicological examinations is presented. The role of evoked potentials in assessing brain dysfunction in general and sensory systems in particular is also presented. Four types of sensory evoked potentials (br...

  16. [The disposing techniques of evoked potentials].

    PubMed

    Liu, H G; Zhou, L; Gu, J; Jing, D Z

    2000-11-01

    This paper is to bring forward the new disposing techniques of evoked potentials which include four aspect techniques of the averaging, the recording, digital sampling and filters about the averaging, evoked potential amplitude, evoked potential latency, evoked potential recording, and evoked potential generations. The technique of the averaging including signal filtering and a periodic averaging, can enhance EP dedection. The commercial EP machines also plot changes in latency between serial EP studies in order to detect trends in peak latency. The modern digital EP recording device consists of sensory stimator, recording amplifiers with analog filters, an analog-to-digital converter, a digital signal averager, and a display and storage system. A sample-and-hold function is one of the recent developments which used EP collectors that provide simultaneous recording with multiple channels employing different time and voltage scales and sampling rates. The EP data may be further processed following A-D conversion by digital filters. PMID:12583248

  17. Somatosensory evoked potentials following proprioceptive stimulation of finger in man.

    PubMed

    Mima, T; Terada, K; Maekawa, M; Nagamine, T; Ikeda, A; Shibasaki, H

    1996-09-01

    Brisk passive flexion of the proximal interphalangeal joint of the middle finger, produced by using a newly devised instrument, elicited evoked potentials on the scalp. The present study carefully excluded the possible contribution of sensory modalities other than proprioception. The initial part of cortical response was a positive deflexion at the contralateral central area (P1 at 34.6 ms after the stimulus). This was followed by a midfrontal negative wave (N1 at 44.8 ms) and a clear positivity at the contralateral centroparietal area (P2 at 48.0 ms). The evoked responses persisted in spite of the abolition of cutaneous and joint afferents of the finger caused by ischemic anesthesia, but they were lost by ischemic anesthesia of the forearm. Thus, the cortical evoked responses obtained in this study most probably reflect muscle afferent inputs. The scalp distribution of P1 suggested that its cortical generator source was different from that of the N20-P20 components of evoked potentials to electrical median nerve stimulation. Brodmann areas 2 and 3a of human brain, which are known to receive deep receptor inputs, are the most plausible generator sites for the early components of the proprioception-related evoked responses. The amplitude of P2 was related to the velocity but not to the magnitude of movement. In conclusion, the present study established a method for recording the evoked responses to the brisk passive movement of the finger joint, which mainly reflect the dynamic aspects of proprioception mediated through muscle afferent. PMID:8891653

  18. Effects of broadband noise on cortical evoked auditory responses at different loudness levels in young adults.

    PubMed

    Sharma, Mridula; Purdy, Suzanne C; Munro, Kevin J; Sawaya, Kathleen; Peter, Varghese

    2014-03-26

    Young adults with no history of hearing concerns were tested to investigate their /da/-evoked cortical auditory evoked potentials (P1-N1-P2) recorded from 32 scalp electrodes in the presence and absence of noise at three different loudness levels (soft, comfortable, and loud), at a fixed signal-to-noise ratio (+3 dB). P1 peak latency significantly increased at soft and loud levels, and N1 and P2 latencies increased at all three levels in the presence of noise, compared with the quiet condition. P1 amplitude was significantly larger in quiet than in noise conditions at the loudest level. N1 amplitude was larger in quiet than in noise for the soft level only. P2 amplitude was reduced in the presence of noise to a similar degree at all loudness levels. The differential effects of noise on P1, N1, and P2 suggest differences in auditory processes underlying these peaks. The combination of level and signal-to-noise ratio should be considered when using cortical auditory evoked potentials as an electrophysiological indicator of degraded speech processing. PMID:24323122

  19. Multivariate analysis of somatosensory evoked potential parameters in normal adults.

    PubMed

    Strenge, H; Gundel, A

    1983-01-01

    Cervical and cortical somatosensory evoked potentials (SEP) to median nerve stimulation were recorded in 65 normal subjects. Absolute peak latencies and amplitudes of cervical components N9, P10, N11, N13, P17, and cortical components P16, N20, P25, and N35 were measured. By means of partial correlations the interdependency of SEP-features could be verified in addition to the well-known dependence on arm length and age. In certain respects our results replicate other studies finding significant correlations between age and latency of early SEP-components as well as inverse relations between age and cervical amplitudes. Further analysis disclosed high inter-correlations between the latencies and between the amplitudes of the cervical and cortical components also revealing a certain exceptional position of the positive wave P17. In contrast to an inverse relation of amplitude and latency of the cervical components there were positive correlations between the respective features in the cortical evoked response. The findings are discussed with regard to the current knowledge about the origins of the SEP-components. PMID:6667105

  20. Case Report of Vestibularly evoked Visual Hallucinations in a Patient with Cortical Blindness.

    PubMed

    Kolev, Ognyan I

    2016-08-01

    Previous work has shown that caloric vestibular stimulation may evoke elementary visual hallucinations in healthy humans, such as different colored lines or dots. Surprisingly, the present case report reveals that the same stimulation can evoke visual hallucinations in a patient with cortical blindness, but with fundamentally different characteristics. The visual hallucinations evoked were complex and came from daily life experiences. Moreover, they did not include other senses beyond vision. This case report suggests that in conditions of cerebral pathology, vestibular-visual interaction may stimulate hallucinogenic subcortical, or undamaged cortical structures, and arouse mechanisms that can generate visual images exclusively. PMID:27246956

  1. Effects of mnemonic load on cortical activity during visual working memory: linking ongoing brain activity with evoked responses.

    PubMed

    Boonstra, Tjeerd W; Powell, Tamara Y; Mehrkanoon, Saeid; Breakspear, Michael

    2013-09-01

    The mechanisms generating task-locked changes in cortical potentials remain poorly understood, despite a wealth of research. It has recently been proposed that ongoing brain oscillations are not symmetric, so that task-related amplitude modulations generate a baseline shift that does not average out, leading to slow event-related potentials. We test this hypothesis using multivariate methods to formally assess the co-variation between task-related evoked potentials and spectral changes in scalp EEG during a visual working memory task, which is known to elicit both evoked and sustained cortical activities across broadly distributed cortical regions. 64-channel EEG data were acquired from eight healthy human subjects who completed a visuo-spatial associative working memory task as memory load was parametrically increased from easy to hard. As anticipated, evoked activity showed a complex but robust spatio-temporal waveform maximally expressed bilaterally in the parieto-occipital and anterior midline regions, showing robust effects of memory load that were specific to the stage of the working memory trial. Similarly, memory load was associated with robust spectral changes in the theta and alpha range, throughout encoding in posterior regions and through maintenance and retrieval in anterior regions, consistent with the additional resources required for decision making in prefrontal cortex. Analysis of the relationship between event-related changes in slow potentials and cortical rhythms, using partial least squares, is indeed consistent with the notion that the former make a causal contribution to the latter. PMID:23583626

  2. Evoked potentials in immobilized cats to a combination of clicks with painful electrocutaneous stimuli

    NASA Technical Reports Server (NTRS)

    Gilinskiy, M. A.; Korsakov, I. A.

    1979-01-01

    Averaged evoked potentials in the auditory, somatosensory, and motor cortical zones, as well as in the mesencephalic reticular formation were recorded in acute experiments on nonanesthetized, immobilized cats. Omission of the painful stimulus after a number of pairings resulted in the appearance of a delayed evoked potential, often resembling the late phases of the response to the painful stimulus. The characteristics of this response are discussed in comparison with conditioned changes of the sensory potential amplitudes.

  3. Auditory and visual evoked potentials during hyperoxia

    NASA Technical Reports Server (NTRS)

    Smith, D. B. D.; Strawbridge, P. J.

    1974-01-01

    Experimental study of the auditory and visual averaged evoked potentials (AEPs) recorded during hyperoxia, and investigation of the effect of hyperoxia on the so-called contingent negative variation (CNV). No effect of hyperoxia was found on the auditory AEP, the visual AEP, or the CNV. Comparisons with previous studies are discussed.

  4. SENSORY EVOKED POTENTIALS: MEASURES OF NEUROTOXICITY

    EPA Science Inventory

    There is a need for tests of sensory function to be incorporated in laboratory and toxicity testing. t is clear that sensory dysfunction may frequently occur, but go undetected, in standard animal toxicological testing protocols. ensory evoked potential technology can be employed...

  5. Visual evoked potentials in infants and children.

    PubMed

    Taylor, M J; McCulloch, D L

    1992-07-01

    Visual evoked potential (VEP) studies are of great value in a wide variety of pediatric patients, including those with disorders of the sensory visual pathway and those at risk for visual pathway damage. VEPs are simple, non-invasive, and are particularly appropriate for infants and young children who cannot communicate visual symptoms or cooperate for standard vision assessment. VEPs in pediatric patients have the following main purposes: (1) detecting lesions causing dysfunction of the sensory visual pathways (the VEP is a sensitive indicator of subclinical lesions and can be used to differentiate visual impairment from visual inattention in young infants); (2) confirming functional loss when disorders of the visual system are present; (3) quantifying visual impairment in patients with known visual disorders, accomplished either empirically by noting the severity of the VEP abnormality to flash and pattern stimuli or by visual acuity estimation studies (early quantification of vision loss allows referral to early intervention programs, which can ameliorate the long-term consequences of the disability); (4) monitoring patients who are at risk for visual complications either from diseases (such as hydrocephalus or neurofibromatosis) or as a complication of therapeutic intervention (e.g., neurosurgery, chemotherapy) to help detect and avoid long-term sequelae of such therapies on the developing nervous system; (5) establishing prognosis for visual and systemic recovery based on flash VEPs for specific pediatric disorders including perinatal asphyxia in full-term neonates, acute-onset cortical blindness, and, to a fair extent, in comatose children; and (6) in some cases, contributing to the differential diagnosis. Abnormalities of flash and/or pattern VEPs are generally nonspecific to the type of exact location of the lesion, except in distinguishing prefrom postchiasmal lesions. However, in certain conditions, such as the hereditary ataxias of childhood, VEP

  6. Optical Recording of Retinal and Visual Cortical Responses Evoked by Electrical Stimulation on the Retina

    NASA Astrophysics Data System (ADS)

    Osanai, Makoto; Sakaehara, Haruko; Sawai, Hajime; Song, Wen-Jie; Yagi, Tetsuya

    To develop a retinal prosthesis for blind patients using an implanted multielectrode array, it is important to study the response properties of retinal ganglion cells and of the visual cortex to localized retinal electrical stimulation. Optical imaging can reveal the spatio-temporal properties of neuronal activity. Therefore, we conducted a calcium imaging study to investigate response properties to local current stimulation in frog retinas, and a membrane potential imaging study to explore the visual cortical responses to retinal stimulation in guinea pigs. In the retina, local current stimuli evoked transient responses in the ganglion cells located near the stimulus electrode. The spatial pattern of the responding area was altered by changing the location of the stimulation. Local electrical stimulation to the retina also caused transient responses in the visual cortex. The responding cortical areas in the primary visual cortex were localized. A spatially different cortical response was observed to stimulation of a different position on the retina. These results suggest that the imaging study has great potential in revealing the spatio-temporal properties of the neuronal response for the retinal prosthesis.

  7. The inhibitory neurotransmitter GABA evokes long-lasting Ca(2+) oscillations in cortical astrocytes.

    PubMed

    Mariotti, Letizia; Losi, Gabriele; Sessolo, Michele; Marcon, Iacopo; Carmignoto, Giorgio

    2016-03-01

    Studies over the last decade provided evidence that in a dynamic interaction with neurons glial cell astrocytes contribut to fundamental phenomena in the brain. Most of the knowledge on this derives, however, from studies monitoring the astrocyte Ca(2+) response to glutamate. Whether astrocytes can similarly respond to other neurotransmitters, including the inhibitory neurotransmitter GABA, is relatively unexplored. By using confocal and two photon laser-scanning microscopy the astrocyte response to GABA in the mouse somatosensory and temporal cortex was studied. In slices from developing (P15-20) and adult (P30-60) mice, it was found that in a subpopulation of astrocytes GABA evoked somatic Ca(2+) oscillations. This response was mediated by GABAB receptors and involved both Gi/o protein and inositol 1,4,5-trisphosphate (IP3 ) signalling pathways. In vivo experiments from young adult mice, revealed that also cortical astrocytes in the living brain exibit GABAB receptor-mediated Ca(2+) elevations. At all astrocytic processes tested, local GABA or Baclofen brief applications induced long-lasting Ca(2+) oscillations, suggesting that all astrocytes have the potential to respond to GABA. Finally, in patch-clamp recordings it was found that Ca(2+) oscillations induced by Baclofen evoked astrocytic glutamate release and slow inward currents (SICs) in pyramidal cells from wild type but not IP3 R2(-/-) mice, in which astrocytic GABAB receptor-mediated Ca(2+) elevations are impaired. These data suggest that cortical astrocytes in the mouse brain can sense the activity of GABAergic interneurons and through their specific recruitment contribut to the distinct role played on the cortical network by the different subsets of GABAergic interneurons. PMID:26496414

  8. Irregular Speech Rate Dissociates Auditory Cortical Entrainment, Evoked Responses, and Frontal Alpha

    PubMed Central

    Kayser, Stephanie J.; Ince, Robin A.A.; Gross, Joachim

    2015-01-01

    The entrainment of slow rhythmic auditory cortical activity to the temporal regularities in speech is considered to be a central mechanism underlying auditory perception. Previous work has shown that entrainment is reduced when the quality of the acoustic input is degraded, but has also linked rhythmic activity at similar time scales to the encoding of temporal expectations. To understand these bottom-up and top-down contributions to rhythmic entrainment, we manipulated the temporal predictive structure of speech by parametrically altering the distribution of pauses between syllables or words, thereby rendering the local speech rate irregular while preserving intelligibility and the envelope fluctuations of the acoustic signal. Recording EEG activity in human participants, we found that this manipulation did not alter neural processes reflecting the encoding of individual sound transients, such as evoked potentials. However, the manipulation significantly reduced the fidelity of auditory delta (but not theta) band entrainment to the speech envelope. It also reduced left frontal alpha power and this alpha reduction was predictive of the reduced delta entrainment across participants. Our results show that rhythmic auditory entrainment in delta and theta bands reflect functionally distinct processes. Furthermore, they reveal that delta entrainment is under top-down control and likely reflects prefrontal processes that are sensitive to acoustical regularities rather than the bottom-up encoding of acoustic features. SIGNIFICANCE STATEMENT The entrainment of rhythmic auditory cortical activity to the speech envelope is considered to be critical for hearing. Previous work has proposed divergent views in which entrainment reflects either early evoked responses related to sound encoding or high-level processes related to expectation or cognitive selection. Using a manipulation of speech rate, we dissociated auditory entrainment at different time scales. Specifically, our

  9. Spinal evoked potentials following transcranial magnetic stimulation.

    PubMed

    Nemoto, J; Sasaki, T; Kikuchi, Y; Konno, Y; Sakuma, J; Kodama, N

    2001-06-01

    Motor evoked potentials by magnetic stimulation is less invasive and causes no pain as opposed to high current electric stimulation. However, the distribution of the magnetic field generated by the round coil has not been fully studied. In this report, we mapped the extent of the magnetic induction flux density, and then the evoked potentials from the spinal cord were investigated by transcranial magnetic stimulation. We also examined the origin of the evoked potentials obtained by the magnetic stimulation. The following results were obtained. The magnetic induction flux density was at its maximum at the edge of the coil. The potentials consisted of a first negative wave and subsequent multiphasic waves. The first negative wave was similar to a response of the subcorticospinal tract in the lower brain stem, while the subsequent multiphasic waves were similar to those of the pyramidal tract. Although magnetic stimulation has certain advantages over electric stimulation, several problems remain to be solved for the monitoring of motor functions in the clinical settings. PMID:11764415

  10. Cortical Variability in the Sensory-Evoked Response in Autism

    ERIC Educational Resources Information Center

    Haigh, Sarah M.; Heeger, David J.; Dinstein, Ilan; Minshew, Nancy; Behrmann, Marlene

    2015-01-01

    Previous findings have shown that individuals with autism spectrum disorder (ASD) evince greater intra-individual variability (IIV) in their sensory-evoked fMRI responses compared to typical control participants. We explore the robustness of this finding with a new sample of high-functioning adults with autism. Participants were presented with…

  11. Pattern visual evoked potentials in hyperthyroidism.

    PubMed Central

    Mitchell, K W; Wood, C M; Howe, J W

    1988-01-01

    Pattern reversal visual evoked potentials (VEPs) have been elicited in 16 female hyperthyroid patients before and after treatment and compared with those from a similar group of age and sex matched control subjects. No effect on latency was seen, and although larger amplitude values were noted in the thyrotoxic group these too were not significant. We would conclude that hyperthyroidism per se has little effect on the pattern reversal VEP, and any observed effect on these potentials is probably due to other factors. PMID:3415945

  12. Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats.

    PubMed

    Nguyen, Christine T; Tsai, Tina I; He, Zheng; Vingrys, Algis J; Lee, Pei Y; Bui, Bang V

    2016-01-01

    The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the electrical responses of the retina to light stimulation, while the VEP measures the corresponding functional integrity of the visual pathways from the retina to the primary visual cortex following the same light event. The ERG waveform can be broken down into components that reflect responses from different retinal neuronal and glial cell classes. The early components of the VEP waveform represent the integrity of the optic nerve and higher cortical centers. These recordings can be conducted in isolation or together, depending on the application. The methodology described in this paper allows simultaneous assessment of retinal and cortical visual evoked electrophysiology from both eyes and both hemispheres. This is a useful way to more comprehensively assess retinal function and the upstream effects that changes in retinal function can have on visual evoked cortical function. PMID:27404129

  13. Conditioning effect of transcranial magnetic stimulation evoking motor-evoked potential on V-wave response.

    PubMed

    Grosprêtre, Sidney; Martin, Alain

    2014-12-01

    The aim of this study was to examine the collision responsible for the volitional V-wave evoked by supramaximal electrical stimulation of the motor nerve during voluntary contraction. V-wave was conditioned by transcranial magnetic stimulation (TMS) over the motor cortex at several inter-stimuli intervals (ISI) during weak voluntary plantar flexions (n = 10) and at rest for flexor carpi radialis muscle (FCR; n = 6). Conditioning stimulations were induced by TMS with intensity eliciting maximal motor-evoked potential (MEPmax). ISIs used were ranging from -20 to +20 msec depending on muscles tested. The results showed that, for triceps surae muscles, conditioning TMS increased the V-wave amplitude (~ +250%) and the associated mechanical response (~ +30%) during weak voluntary plantar flexion (10% of the maximal voluntary contraction -MVC) for ISIs ranging from +6 to +18 msec. Similar effect was observed at rest for the FCR with ISI ranging from +6 to +12 msec. When the level of force was increased from 10 to 50% MVC or the conditioning TMS intensity was reduced to elicit responses of 50% of MEPmax, a significant decrease in the conditioned V-wave amplitude was observed for the triceps surae muscles, linearly correlated to the changes in MEP amplitude. The slope of this correlation, as well as the electro-mechanical efficiency, was closed to the identity line, indicating that V-wave impact at muscle level seems to be similar to the impact of cortical stimulation. All these results suggest that change in V-wave amplitude is a great index to reflect changes in cortical neural drive addressed to spinal motoneurons. PMID:25501438

  14. Analysis of evoked lumbosacral potentials in man.

    PubMed Central

    Delbeke, J; McComas, A J; Kopec, S J

    1978-01-01

    Surface electrodes have been used to record potentials evoked in the lumbosacral region of 15 healthy volunteers after tibial nerve stimulation. By monitoring the M waves and H reflexes in the triceps surae muslces and by comparing the responses recorded over the roots with those over the lower cord, it was possible to identify the neural substrates responsible for several of the components in the responses. The findings are compared with those of previous studies in man and in other mammalian preparations. PMID:650237

  15. Analysis of evoked lumbosacral potentials in man.

    PubMed

    Delbeke, J; McComas, A J; Kopec, S J

    1978-04-01

    Surface electrodes have been used to record potentials evoked in the lumbosacral region of 15 healthy volunteers after tibial nerve stimulation. By monitoring the M waves and H reflexes in the triceps surae muslces and by comparing the responses recorded over the roots with those over the lower cord, it was possible to identify the neural substrates responsible for several of the components in the responses. The findings are compared with those of previous studies in man and in other mammalian preparations. PMID:650237

  16. [Cerebral evoked potentials in comatose states of various etiology].

    PubMed

    Akimov, G A; Nasonkin, O S; Semin, G F; Pashkovskiĭ, E V

    1983-01-01

    The authors studied the evoked potentials (EPs) of the brain cortex in patients in comatose states of various etiology as well as the EPs of the brain cortical and subcortical structures of the animals during simulation of the conditions studied in clinical practice. A sharp drop in the amplitude of early waves and an increase in the amplitude and latency of late EP waves in all the cerebral structures irrespective of the coma genesis were disclosed. The changes were of a simultaneous and generalized character with a greater similarity between the EPs of the cortical zones but an increase of their difference from the subcortical structures. These facts are explained by the deprivation of the nonspecific systems of both cortical and local inhibitory influence which leads to the late activation of the brain specific systems. It is assumed that the space-time dissociation in the action of various cerebral systems is, regardless of the coma genesis, one of the principal mechanisms giving rise to disorders of information perception, analysis and processing. PMID:6666451

  17. 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

  18. 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. PMID:24599314

  19. A single dose of lorazepam reduces paired-pulse suppression of median nerve evoked somatosensory evoked potentials.

    PubMed

    Stude, Philipp; Lenz, Melanie; Höffken, Oliver; Tegenthoff, Martin; Dinse, Hubert

    2016-05-01

    Paired-pulse behaviour in the somatosensory cortex is an approach to obtain insights into cortical processing modes and to obtain markers of changes of cortical excitability attributable to learning or pathological states. Numerous studies have demonstrated suppression of the response to the stimulus that follows a first one after a short interval, but the underlying mechanisms remain elusive, although there is agreement that GABAergic mechanisms seem to play a crucial role. We therefore aimed to explore the influence of the GABAA agonist lorazepam on paired-pulse somatosensory evoked potentials (SEPs). We recorded and analysed SEPs after paired median nerve stimulation in healthy individuals before and after they had received a single dose of 2.5 mg of lorazepam as compared with a control group receiving placebo. Paired-pulse suppression was expressed as a ratio of the amplitudes of the second and the first peaks. We found that, after lorazepam application, paired-pulse suppression of the cortical N20 component remained unchanged, but suppression of the N20-P25 complex was significantly reduced, indicative of GABAergic involvement in intracortical processing. Our data suggest that lorazepam most likely enhances inhibition within the cortical network of interneurons responsible for creating paired-pulse suppression, leading to reduced inhibitory drive with a subsequently reduced amount of suppression. The results provide further evidence that GABAA -mediated mechanisms are involved in the generation of median nerve evoked paired-pulse suppression. PMID:26929110

  20. FOCAL LESIONS OF VISUAL CORTEX: EFFECTS ON VISUAL EVOKED POTENTIALS IN RATS

    EPA Science Inventory

    Focal lesions were placed in the visual cortex of Long-Evans hooded rats, immediately below skull screw recording electrodes. Lesions were produced by heat and extended an average depth of about 0.9 mm below the cortical surface. Evoked potentials recorded from the electrode over...

  1. Long Latency Auditory Evoked Potentials during Meditation.

    PubMed

    Telles, Shirley; Deepeshwar, Singh; Naveen, Kalkuni Visweswaraiah; Pailoor, Subramanya

    2015-10-01

    The auditory sensory pathway has been studied in meditators, using midlatency and short latency auditory evoked potentials. The present study evaluated long latency auditory evoked potentials (LLAEPs) during meditation. Sixty male participants, aged between 18 and 31 years (group mean±SD, 20.5±3.8 years), were assessed in 4 mental states based on descriptions in the traditional texts. They were (a) random thinking, (b) nonmeditative focusing, (c) meditative focusing, and (d) meditation. The order of the sessions was randomly assigned. The LLAEP components studied were P1 (40-60 ms), N1 (75-115 ms), P2 (120-180 ms), and N2 (180-280 ms). For each component, the peak amplitude and peak latency were measured from the prestimulus baseline. There was significant decrease in the peak latency of the P2 component during and after meditation (P<.001; analysis of variance and post hoc analysis with Bonferroni adjustment). The P1, P2, and N2 components showed a significant decrease in peak amplitudes during random thinking (P<.01; P<.001; P<.01, respectively) and nonmeditative focused thinking (P<.01; P<.01; P<.05, respectively). The results suggest that meditation facilitates the processing of information in the auditory association cortex, whereas the number of neurons recruited was smaller in random thinking and non-meditative focused thinking, at the level of the secondary auditory cortex, auditory association cortex and anterior cingulate cortex. PMID:25380593

  2. Long latency auditory evoked potential in term and premature infants.

    PubMed

    Didoné, Dayane Domeneghini; Garcia, Michele Vargas; da Silveira, Aron Ferreira

    2014-01-01

    Introduction The research in long latency auditory evokes potentials (LLAEP) in newborns is recent because of the cortical structure maturation, but studies note that these potentials may be evidenced at this age and could be considered as indicators of cognitive development. Purpose To research the exogenous potentials in term and premature infants during their first month of life. Materials and Methods The sample consisted of 25 newborns, 15 term and 10 premature infants. The infants with gestational age under 37 weeks were considered premature. To evaluate the cortical potentials, the infants remained in natural sleep. The LLAEPs were researched binaurally, through insertion earphones, with frequent /ba/ and rare /ga/ speech stimuli in the intensity of 80 dB HL (decibel hearing level). The frequent stimuli presented a total of 80% of the presentations, and the rare, 20%. The data were statistically analyzed. Results The average gestational age of the term infants was 38.9 weeks (± 1.3) and for the premature group, 33.9 weeks (± 1.6). It was possible to observe only the potentials P1 and N1 in both groups, but there was no statistically significant difference for the latencies of the components P1 and N1 (p > 0.05) between the groups. Conclusion It was possible to observe the exogenous components P1 and N1 of the cortical potentials in both term and preterm newborns of no more than 1 month of age. However, there was no difference between the groups. PMID:25992057

  3. Quantifying attentional modulation of auditory-evoked cortical responses from single-trial electroencephalography

    PubMed Central

    Choi, Inyong; Rajaram, Siddharth; Varghese, Lenny A.; Shinn-Cunningham, Barbara G.

    2013-01-01

    Selective auditory attention is essential for human listeners to be able to communicate in multi-source environments. Selective attention is known to modulate the neural representation of the auditory scene, boosting the representation of a target sound relative to the background, but the strength of this modulation, and the mechanisms contributing to it, are not well understood. Here, listeners performed a behavioral experiment demanding sustained, focused spatial auditory attention while we measured cortical responses using electroencephalography (EEG). We presented three concurrent melodic streams; listeners were asked to attend and analyze the melodic contour of one of the streams, randomly selected from trial to trial. In a control task, listeners heard the same sound mixtures, but performed the contour judgment task on a series of visual arrows, ignoring all auditory streams. We found that the cortical responses could be fit as weighted sum of event-related potentials evoked by the stimulus onsets in the competing streams. The weighting to a given stream was roughly 10 dB higher when it was attended compared to when another auditory stream was attended; during the visual task, the auditory gains were intermediate. We then used a template-matching classification scheme to classify single-trial EEG results. We found that in all subjects, we could determine which stream the subject was attending significantly better than by chance. By directly quantifying the effect of selective attention on auditory cortical responses, these results reveal that focused auditory attention both suppresses the response to an unattended stream and enhances the response to an attended stream. The single-trial classification results add to the growing body of literature suggesting that auditory attentional modulation is sufficiently robust that it could be used as a control mechanism in brain–computer interfaces (BCIs). PMID:23576968

  4. Reactivation of visual-evoked activity in human cortical networks.

    PubMed

    Chelaru, Mircea I; Hansen, Bryan J; Tandon, Nitin; Conner, Chris R; Szukalski, Susann; Slater, Jeremy D; Kalamangalam, Giridhar P; Dragoi, Valentin

    2016-06-01

    In the absence of sensory input, neuronal networks are far from being silent. Whether spontaneous changes in ongoing activity reflect previous sensory experience or stochastic fluctuations in brain activity is not well understood. Here we demonstrate reactivation of stimulus-evoked activity that is distributed across large areas in the human brain. We performed simultaneous electrocorticography recordings from occipital, parietal, temporal, and frontal areas in awake humans in the presence and absence of sensory stimulation. We found that, in the absence of visual input, repeated exposure to brief natural movies induces robust stimulus-specific reactivation at individual recording sites. The reactivation sites were characterized by greater global connectivity compared with those sites that did not exhibit reactivation. Our results indicate a surprising degree of short-term plasticity across multiple networks in the human brain as a result of repeated exposure to unattended information. PMID:26984423

  5. Resting Heart Rate and Auditory Evoked Potential

    PubMed Central

    Fiuza Regaçone, Simone; Baptista de Lima, Daiane Damaris; Engrácia Valenti, Vitor; Figueiredo Frizzo, Ana Cláudia

    2015-01-01

    The objective of this study was to evaluate the association between rest heart rate (HR) and the components of the auditory evoked-related potentials (ERPs) at rest in women. We investigated 21 healthy female university students between 18 and 24 years old. We performed complete audiological evaluation and measurement of heart rate for 10 minutes at rest (heart rate monitor Polar RS800CX) and performed ERPs analysis (discrepancy in frequency and duration). There was a moderate negative correlation of the N1 and P3a with rest HR and a strong positive correlation of the P2 and N2 components with rest HR. Larger components of the ERP are associated with higher rest HR. PMID:26504838

  6. [Auditory evoked potentials under attentional lapses].

    PubMed

    Lazarev, I E; Bryzgalov, D V; Osokina, E S; Viazovtseva, A A; Antonenko, A S; Arkhipova, E A; Chernyshev, B V

    2014-01-01

    In order to study spontaneous attentional lapses the experimental task was used that created a moderately high attentional load and involved response choice based on stimulus feature conjunction. The participant's average correct response rate was 85.1%; they made errors in 9.6% trials and response omissions in 5.4% trials. Peak N1 of the evoked potential was consistent across all behavioral outcomes, while peak P2 amplitude was significantly greater before errors and response omissions compared to correct responses. The analysis of polygraphic indexes (ECG, EMG, SGR) did not reveal any arousal level reduction before attentional lapses. The proposed interpretation of the results obtained is based on the assumption that attentional lapses are mediated by the suppression of external stimuli information processing caused by the state of mind-wandering. PMID:25723016

  7. Prognostic value of cortically induced motor evoked activity by TMS in chronic stroke: Caveats from a revealing single clinical case

    PubMed Central

    2012-01-01

    Background We report the case of a chronic stroke patient (62 months after injury) showing total absence of motor activity evoked by transcranial magnetic stimulation (TMS) of spared regions of the left motor cortex, but near-to-complete recovery of motor abilities in the affected hand. Case presentation Multimodal investigations included detailed TMS based motor mapping, motor evoked potentials (MEP), and Cortical Silent period (CSP) as well as functional magnetic resonance imaging (fMRI) of motor activity, MRI based lesion analysis and Diffusion Tensor Imaging (DTI) Tractography of corticospinal tract (CST). Anatomical analysis revealed a left hemisphere subinsular lesion interrupting the descending left CST at the level of the internal capsule. The absence of MEPs after intense TMS pulses to the ipsilesional M1, and the reversible suppression of ongoing electromyographic (EMG) activity (indexed by CSP) demonstrate a weak modulation of subcortical systems by the ipsilesional left frontal cortex, but an inability to induce efficient descending volleys from those cortical locations to right hand and forearm muscles. Functional MRI recordings under grasping and finger tapping patterns involving the affected hand showed slight signs of subcortical recruitment, as compared to the unaffected hand and hemisphere, as well as the expected cortical activations. Conclusions The potential sources of motor voluntary activity for the affected hand in absence of MEPs are discussed. We conclude that multimodal analysis may contribute to a more accurate prognosis of stroke patients. PMID:22682434

  8. 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.

  9. Deconvolution of the vestibular evoked myogenic potential.

    PubMed

    Lütkenhöner, Bernd; Basel, Türker

    2012-02-01

    The vestibular evoked myogenic potential (VEMP) and the associated variance modulation can be understood by a convolution model. Two functions of time are incorporated into the model: the motor unit action potential (MUAP) of an average motor unit, and the temporal modulation of the MUAP rate of all contributing motor units, briefly called rate modulation. The latter is the function of interest, whereas the MUAP acts as a filter that distorts the information contained in the measured data. Here, it is shown how to recover the rate modulation by undoing the filtering using a deconvolution approach. The key aspects of our deconvolution algorithm are as follows: (1) the rate modulation is described in terms of just a few parameters; (2) the MUAP is calculated by Wiener deconvolution of the VEMP with the rate modulation; (3) the model parameters are optimized using a figure-of-merit function where the most important term quantifies the difference between measured and model-predicted variance modulation. The effectiveness of the algorithm is demonstrated with simulated data. An analysis of real data confirms the view that there are basically two components, which roughly correspond to the waves p13-n23 and n34-p44 of the VEMP. The rate modulation corresponding to the first, inhibitory component is much stronger than that corresponding to the second, excitatory component. But the latter is more extended so that the two modulations have almost the same equivalent rectangular duration. PMID:22079097

  10. Effects of dehydroepiandrosterone sulfate on the evoked cortical activity of controls and of brain-injured rats.

    PubMed

    Lür, György; Rákos, Gabriella; Juhász-Vedres, Gabriella; Farkas, Tamás; Kis, Zsolt; Toldi, József

    2006-01-01

    1. Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are sex hormone precursors which exert marked neurotrophic and/or neuroprotective activity in the central nervous system (CNS). 2. In the present electrophysiological experiments, we studied the effects of peripherally administered DHEAS on responses of the primary somatosensory (SSI) and motor cortices (MI) of (i) anesthetized controls and (ii) MI focal cold-lesioned rats. (iii) The effects of DHEAS on the field excitatory postsynaptic potentials (fEPSPs) were also studied in vitro brain slices. DHEAS (50 mg/kg) was injected subcutaneously 12 h before and immediately after cold lesion induction. The anesthetized rats were fixed in a stereotaxic frame, the SSI and MI were exposed, and control SSI and MI responses were evoked by contralateral whisker pad stimulation. After registration of the evoked responses for a 35-min period, a copper cylinder (2 mm in diameter) cooled with a mixture of acetone and dry ice (-78 degrees C) was applied to produce a lesion in the MI and the registration of the evoked responses was then continued for an additional 360 min. 3. In the controls, DHEAS administration resulted in slight increases in amplitude of both the SSI and the MI responses. After focal cold lesion induction, the most significant reduction in amplitude was observed at the focus of the lesion in the primary MI, but the amplitudes of the SSI responses were also decreased. After 3-5 h of lesion induction, the amplitudes started to increase around the injury in the primary MI, while the SSI response had already started to recover 2 h after induction of the MI lesion. In the course of the postlesion recovery period, the MI responses peripherally to the center of the lesion frequently exhibited extremely high and low amplitudes. The paired-pulse paradigm revealed changing, but basically high levels of disinhibition and facilitation in extended cortical areas after focal cortical cold lesion induction. The deviations

  11. Somatosensory evoked potentials and blood lactate levels.

    PubMed

    Perciavalle, Valentina; Alagona, Giovanna; De Maria, Giulia; Rapisarda, Giuseppe; Costanzo, Erminio; Perciavalle, Vincenzo; Coco, Marinella

    2015-09-01

    We compared, in 20 subjects, the effects of high blood lactate levels on amplitude and latency of P1, N1, P2 and N2 components of lower limb somatosensory evoked potential (SEP), an useful, noninvasive tool for assessing the transmission of the afferent volley from periphery up to the cortex. SEPs were recorded from CPz located over the somatosensory vertex and referenced to FPz with a clavicle ground. Measurements were carried out before, at the end as well as 10 and 20 min after the conclusion of a maximal exercise carried out on a mechanically braked cycloergometer. After the exercise, P2-N2 amplitudes as well as latency of P1 and N1 components showed small but significant reductions. On the contrary, latency of N2 component exhibited a significant increase after the exercise's conclusion. These results suggest that blood lactate appears to have a protective effect against fatigue, at least at level of primary somatosensory cortex, although at the expense of efficiency of adjacent areas. PMID:25876852

  12. Auditory evoked potential measurements with cetaceans

    NASA Astrophysics Data System (ADS)

    Mann, David; Cook, Mandy; Bauer, Gordon; Fellner, Wendi; Wells, Randy

    2005-04-01

    Auditory evoked potentials (AEPs) allow researchers to measure the hearing abilities of animals that would be difficult or impossible to train for behavioral measurements of hearing. The hearing abilities of live-stranded cetaceans and wild dolphins can only be made with AEP techniques. In these situations, time with the animal is often restricted to an hour or less, and there is often little control over the acoustic environment in which the tests are performed. AEP measurements may be made while the animals are in air or in shallow pools. For cetaceans in air, sounds are typically presented with a suction cup jawphone. For cetaceans in water, sounds may be presented in a direct field (with the transducer located at some distance from the test subject) or with a jawphone. In each of these situations it is important to understand how thresholds derived from AEP measurements compare with behavioral hearing measurements. Examples of AEP measurements from wild and live-stranded cetaceans are presented to illustrate their usefulness and the constraints under which these measurements must be made. AEP measurements from bottlenose dolphins in air and in water are also compared with their behavioral audiograms.

  13. Auditory evoked potential measurements in elasmobranchs

    NASA Astrophysics Data System (ADS)

    Casper, Brandon; Mann, David

    2005-04-01

    Auditory evoked potentials (AEP) were first used to examine hearing in elasmobranchs by Corwin and Bullock in the late 1970s and early 1980s, marking the first time AEPs had been measured in fishes. Results of these experiments identified the regions of the ear and brain in which sound is processed, though no actual hearing thresholds were measured. Those initial experiments provided the ground work for future AEP experiments to measure fish hearing abilities in a manner that is much faster and more convenient than classical conditioning. Data will be presented on recent experiments in which AEPs were used to measure the hearing thresholds of two species of elasmobranchs: the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicencis. Audiograms were analyzed and compared to previously published audiograms obtained using classical conditioning with results indicating that hearing thresholds were similar for the two methods. These data suggest that AEP testing is a viable option when measuring hearing in elasmobranchs and can increase the speed in which future hearing measurements can be obtained.

  14. Respiratory-Related Evoked Potentials During Sleep in Children

    PubMed Central

    Melendres, M. Cecilia; Marcus, Carole L.; Abi-Raad, Ronnie F.; Trescher, William H.; Lutz, Janita M.; Colrain, I. M.

    2008-01-01

    Study Objectives: The respiratory related evoked potential (RREP) has been previously recorded in children and adults during wakefulness and in adults during sleep. However, there have been no data on RREP during sleep in children. We thus examined children during sleep to determine whether early RREP components would be maintained during all sleep Design and Participants: Twelve healthy, nonsnoring children, aged 5–12 years, screened by polysomnography and found to have no sleep disorders were assessed during stage 2 sleep, slow wave sleep, and REM sleep. Brief occlusions were presented via an occlusion valve at the inspiratory port of a non-rebreathing valve as interruptions of inspiration. EEG responses were averaged and assessed for the presence of early and late RREP components. Results: Robust early components were seen in the majority of subjects in all sleep stages. Late components were also present, although with some apparent differences compared to those previously reported in adults (using the same recording protocol and an almost identical method of stimulus presentation). Specifically, N350 and N550 were less readily differentiated as separate components, and the N550 did not display the clear anterior-posterior amplitude gradient that is ubiquitous in adults. Conclusion: Cortical processing of respiratory-related information persists throughout sleep in children. The pattern of activation in the late components appear to reflect differences in the structure of the developing brain prior to the process of dendritic pruning associated with adolescence. Citation: Melendres MC; Marcus CL; Abi-Raad RF; Trescher WH; Lutz JM; Colrain IM. Respiratory-related evoked potentials during sleep in children. SLEEP 2008;31(1):55-61. PMID:18220078

  15. Vestibular evoked myogenic potentials in Bell's palsy.

    PubMed

    Krbot Skoric, Magdalena; Adamec, Ivan; Habek, Mario

    2014-10-01

    The aim of the present study was to evaluate vestibular nerve involvement in patients with Bell's palsy with ocular and cervical vestibular evoked myogenic potentials (oVEMP and cVEMP). Ten patients who were diagnosed with Bell's palsy and ten healthy controls were included. All patients underwent VEMP recordings within 6 days after their initial presentation. Patients with Bell's palsy had greater oVEMP asymmetry ratio comparing to healthy controls (-38.4 ± 28.7 % vs -1.3 ± 19.3 %, p = 0.005). As well N10 latencies of the oVEMP response were prolonged comparing to healthy controls (11.575 vs 9.72 ms). There was no difference in cVEMP asymmetry ratio or latencies between groups. We found no correlation between House-Brackmann grading scale and oVEMP asymmetry ratio (r = 0.003, p = 0.994). There are three possible explanations for increased oVEMP amplitudes on the affected side: (1) oVEMP response on the ipsilateral eye could be contaminated by facial nerve activity (blink reflex); (2) the amplitude of N10-P33 could be affected through the stapedial reflex; and (3) increased oVEMP amplitude could be the consequence of the vestibular nerve dysfunction itself, with prolonged latencies of the N10 oVEMP further supporting this explanation. The results of this study indicate possible involvement of the superior branch of the vestibular nerve in patients with Bell's palsy. PMID:24916836

  16. Cortical Thinning in Healthy Aging Correlates with Larger Motor-Evoked EEG Desynchronization

    PubMed Central

    Provencher, David; Hennebelle, Marie; Cunnane, Stephen C.; Bérubé-Lauzière, Yves; Whittingstall, Kevin

    2016-01-01

    Although electroencephalography (EEG) is a valuable tool to investigate neural activity in patients and controls, exactly how local anatomy impacts the measured signal remains unclear. Better characterizing this relationship is important to improve the understanding of how inter-subject differences in the EEG signal are related to neural activity. We hypothesized that cortical structure might affect event-related desynchronization (ERD) in EEG. Since aging is a well-documented cause of cortical thinning, we investigated the effects of cortical thickness (CT) and cortical depth (CD – the skull-to-cortex distance) on ERD using anatomical MRI and motor-evoked EEG in 17 healthy young adults and 20 healthy older persons. Results showed a significant negative correlation between ERD and CT, but no consistent relationship between ERD and CD. A thinner cortex was associated with a larger ERD in the α/β band and correcting for CT removed most of the inter-group difference in ERD. This indicates that differences in neural activity might not be the primary cause for the observed aging-related differences in ERD, at least in the motor cortex. Further, it emphasizes the importance of considering conditions affecting the EEG signal, such as cortical anatomical changes due to aging, when interpreting differences between healthy controls and/or patients. PMID:27064767

  17. Effect of extradural morphine on somatosensory evoked potentials to dermatomal stimulation.

    PubMed

    Lund, C; Selmar, P; Hansen, O B; Jensen, C M; Kehlet, H

    1987-11-01

    The effect of the extradural (L2-3) administration of morphine 6 mg on early (less than 0.5 s) somatosensory evoked cortical potentials (SEP) to electrical stimulation of the L1- and S1-dermatomes was examined in eight patients. Extradural morphine did not influence SEP amplitude. SEP latency did not change, except for a minor increase in the latencies of the onset and the P2 components following S1 stimulation. PMID:3689615

  18. Brainstem auditory evoked potential in clinical hypothyroidism

    PubMed Central

    Sharma, Kirti; Kumar, Naresh; Behera, Joshil Kumar; Sood, Sushma; Das, Sibadatta; Madan, Harnam Singh

    2015-01-01

    Objectives: The association of hypothyroidism with impairment of hearing is known to occur. It may be of any kind i. e., conductive, sensorineural or mixed. The aim of this study is to assess auditory pathway by brainstem auditory evoked potential (BAEP) in newly diagnosed patients of clinical hypothyroidism and healthy sex- and age-matched controls. Materials and Methods: The study included 25 healthy age- and sex-matched controls (Group I) and 25 patients of newly diagnosed clinical hypothyroidism (Group II). The recording was taken by using RMS EMG EP MK2 equipment. Statistical Analysis Used: Unpaired Student's t test. Results: There was a significant increase in wave IV (5.16 ± 0.85 ms) and wave V (6.17 ± 0.89 ms) latencies of right ear BAEP of Group II in comparison to wave IV (4.66 ± 0.39 ms) and wave V (5.49 ± 0.26 ms) of Group I. Wave V of left ear BAEP of Group II was also prolonged (6 ± 0.61 ms) in comparison to Group I (5.47 ± 0.35 ms). There was a significant difference in inter-peak latencies IPL I -V (4.44 ± 0.66 ms) and IPL III -V (2.2 ± 0.5 ms) of right ear BAEP of Group II in comparison to IPL I -V (3.94 ± 0.31 ms) and IPL III -V (1.84 ± 0.34 ms) of Group I. A significant prolongation was also found of IPL I -V (4.36 ± 0.59 ms) and IPL III -V (2.2 ± 0.42 ms) of left ear BAEP of Group II in comparison to IPL I -V (3.89 ± 0.3 ms) and IPL III -V (1.85 ± 0.3 ms) of Group I. Conclusion: Prolongation of wave IV and V along with inter-peak latencies in BAEP of both ears suggests that central auditory pathway is affected significantly in clinical hypothyroid patients. PMID:26229759

  19. Evoked response study tool: a portable, rugged system for single and multiple auditory evoked potential measurements.

    PubMed

    Finneran, James J

    2009-07-01

    Although the potential of using portable auditory evoked potential systems for field testing of stranded cetaceans has been long recognized, commercial systems for evoked potential measurements generally do not possess the bandwidth required for testing odontocete cetaceans and are not suitable for field use. As a result, there have been a number of efforts to develop portable evoked potential systems for field testing of cetaceans. This paper presents another such system, called the evoked response study tool (EVREST). EVREST is a Windows-based hardware/software system designed for calibrating sound stimuli and recording and analyzing transient and steady-state evoked potentials. The EVREST software features a graphical user interface, real-time analysis and visualization of recorded data, a variety of stimulus options, and a high level of automation. The system hardware is portable, rugged, battery-powered, and possesses a bandwidth that encompasses the audible range of echolocating odontocetes, making the system suitable for field testing of stranded or rehabilitating cetaceans. PMID:19603907

  20. Transcranial magnetic motor-evoked potentials in scoliosis surgery.

    PubMed

    Glassman, S D; Zhang, Y P; Shields, C B; Johnson, J R; Linden, R D

    1995-10-01

    Spinal cord monitoring using SSEPs is an accepted adjunct in the surgical correction of spinal deformities, but does not directly assess motor function. Motor-evoked potentials have been introduced in an effort to meet this important need. In this series of 18 patients, the feasibility of intraoperative monitoring using transcranial magnetic motor-evoked potentials is documented. The potential value of this neurophysiologic monitoring technique, as well as the pitfalls in interpretation, are reviewed. PMID:8584459

  1. Click- and chirp-evoked human compound action potentials.

    PubMed

    Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

    2010-05-01

    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

  2. Alterations in oropharyngeal sensory evoked potentials (PSEP) with Parkinson's disease.

    PubMed

    Pitts, Teresa; Hegland, Karen Wheeler; Sapienza, Christine M; Bolser, Donald C; Davenport, Paul W

    2016-07-15

    Movement of a food bolus from the oral cavity into the oropharynx activates pharyngeal sensory mechanoreceptors. Using electroencephalography, somatosensory cortical-evoked potentials resulting from oropharyngeal mechanical stimulation (PSEP) have been studied in young healthy individuals. However, limited information is known about changes in processing of oropharyngeal afferent signals with Parkinson's disease (PD). To determine if sensory changes occurred with a mechanical stimulus (air-puff) to the oropharynx, two stimuli (S1-first; S2-s) were delivered 500ms apart. Seven healthy older adults (HOA; 3 male and 4 female; 72.2±6.9 years of age), and thirteen persons diagnosed with idiopathic Parkinson's disease (PD; 11 male and 2 female; 67.2±8.9 years of age) participated. Results demonstrated PSEP P1, N1, and P2 component peaks were identified in all participants, and the N2 peak was present in 17/20 participants. Additionally, the PD participants had a decreased N2 latency and gated the P1, P2, and N2 responses (S2/S1 under 0.6). Compared to the HOAs, the PD participants had greater evidence of gating the P1 and N2 component peaks. These results suggest that persons with PD experience changes in sensory processing of mechanical stimulation of the pharynx to a greater degree than age-matched controls. In conclusion, the altered processing of sensory feedback from the pharynx may contribute to disordered swallow in patients with PD. PMID:27090350

  3. Source localisation of visual evoked potentials in congenitally deaf individuals.

    PubMed

    Hauthal, Nadine; Thorne, Jeremy D; Debener, Stefan; Sandmann, Pascale

    2014-05-01

    Previous studies have suggested that individuals deprived of auditory input can compensate with specific superior abilities in the remaining sensory modalities. To better understand the neural basis of deafness-induced changes, the present study used electroencephalography to examine visual functions and cross-modal reorganization of the auditory cortex in deaf individuals. Congenitally deaf participants and hearing controls were presented with reversing chequerboard stimuli that were systematically modulated in luminance ratio. The two groups of participants showed similar modulation of visual evoked potential (VEP) amplitudes (N85, P110) and latencies (P110) as a function of luminance ratio. Analysis of VEPs revealed faster neural processing in deaf participants compared with hearing controls at early stages of cortical visual processing (N85). Deaf participants also showed higher amplitudes (P110) than hearing participants. In contrast to our expectations, the results from VEP source analysis revealed no clear evidence for cross-modal reorganization in the auditory cortex of deaf participants. However, deaf participants tended to show higher activation in posterior parietal cortex (PPC). Moreover, modulation of PPC responses as a function of luminance was also stronger in deaf than in hearing participants. Taken together, these findings are an indication of more efficient neural processing of visual information in the deaf, which may relate to functional changes, in particular in multisensory parietal cortex, as a consequence of early auditory deprivation. PMID:24337445

  4. Brainstem Auditory Evoked Potential in HIV-Positive Adults

    PubMed Central

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

    2015-01-01

    Background To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. Material/Methods 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. Results 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. Conclusions 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. PMID:26485202

  5. KETAMINE ALTERS RAT FLASH EVOKED POTENTIALS (JOURNAL VERSION)

    EPA Science Inventory

    Discovering the neurotransmitters involved in the generation of flash evoked potentials (FEPs) would enhance the use of FEPs in screening for and assessment of neurological damage. Recent evidence suggests that the excitatory amino acids, glutamate and aspartate, may be transmitt...

  6. Interaction of electrically evoked activity with intrinsic dynamics of cultured cortical networks with and without functional fast GABAergic synaptic transmission

    PubMed Central

    Baltz, Thomas; Voigt, Thomas

    2015-01-01

    The modulation of neuronal activity by means of electrical stimulation is a successful therapeutic approach for patients suffering from a variety of central nervous system disorders. Prototypic networks formed by cultured cortical neurons represent an important model system to gain general insights in the input–output relationships of neuronal tissue. These networks undergo a multitude of developmental changes during their maturation, such as the excitatory–inhibitory shift of the neurotransmitter GABA. Very few studies have addressed how the output properties to a given stimulus change with ongoing development. Here, we investigate input–output relationships of cultured cortical networks by probing cultures with and without functional GABAAergic synaptic transmission with a set of stimulation paradigms at various stages of maturation. On the cellular level, low stimulation rates (<15 Hz) led to reliable neuronal responses; higher rates were increasingly ineffective. Similarly, on the network level, lowest stimulation rates (<0.1 Hz) lead to maximal output rates at all ages, indicating a network wide refractory period after each stimulus. In cultures aged 3 weeks and older, a gradual recovery of the network excitability within tens of milliseconds was in contrast to an abrupt recovery after about 5 s in cultures with absent GABAAergic synaptic transmission. In these GABA deficient cultures evoked responses were prolonged and had multiple discharges. Furthermore, the network excitability changed periodically, with a very slow spontaneous change of the overall network activity in the minute range, which was not observed in cultures with absent GABAAergic synaptic transmission. The electrically evoked activity of cultured cortical networks, therefore, is governed by at least two potentially interacting mechanisms: A refractory period in the order of a few seconds and a very slow GABA dependent oscillation of the network excitability. PMID:26236196

  7. Interaction of electrically evoked activity with intrinsic dynamics of cultured cortical networks with and without functional fast GABAergic synaptic transmission.

    PubMed

    Baltz, Thomas; Voigt, Thomas

    2015-01-01

    The modulation of neuronal activity by means of electrical stimulation is a successful therapeutic approach for patients suffering from a variety of central nervous system disorders. Prototypic networks formed by cultured cortical neurons represent an important model system to gain general insights in the input-output relationships of neuronal tissue. These networks undergo a multitude of developmental changes during their maturation, such as the excitatory-inhibitory shift of the neurotransmitter GABA. Very few studies have addressed how the output properties to a given stimulus change with ongoing development. Here, we investigate input-output relationships of cultured cortical networks by probing cultures with and without functional GABAAergic synaptic transmission with a set of stimulation paradigms at various stages of maturation. On the cellular level, low stimulation rates (<15 Hz) led to reliable neuronal responses; higher rates were increasingly ineffective. Similarly, on the network level, lowest stimulation rates (<0.1 Hz) lead to maximal output rates at all ages, indicating a network wide refractory period after each stimulus. In cultures aged 3 weeks and older, a gradual recovery of the network excitability within tens of milliseconds was in contrast to an abrupt recovery after about 5 s in cultures with absent GABAAergic synaptic transmission. In these GABA deficient cultures evoked responses were prolonged and had multiple discharges. Furthermore, the network excitability changed periodically, with a very slow spontaneous change of the overall network activity in the minute range, which was not observed in cultures with absent GABAAergic synaptic transmission. The electrically evoked activity of cultured cortical networks, therefore, is governed by at least two potentially interacting mechanisms: A refractory period in the order of a few seconds and a very slow GABA dependent oscillation of the network excitability. PMID:26236196

  8. Effect of experimental scotoma size and shape on the binocular and monocular pattern visual evoked potential.

    PubMed

    Geer, I; Spafford, M M

    1994-01-01

    A small experimental, central scotoma significantly attenuates the human pattern visual evoked potential. The steady-state pattern visual evoked potential was recorded from seven visually normal adults who viewed a reversing checkerboard with 24' checks and a central scotoma that varied in size and shape. We found that square scotomas had to be at least 3 x 3 degrees to significantly (p < 0.05) attenuate the pattern visual evoked potential. Receptor density has been shown to be greater along the horizontal meridian than the vertical meridian. We hypothesized that this results in greater cortical representation of the horizontal meridian than the vertical meridian and, therefore, the pattern visual evoked potential might be significantly attenuated by a smaller rectangular scotoma oriented along the horizontal meridian than along the vertical meridian. One dimension of the rectangular scotoma was fixed at either 1 degree or 3 degrees, while the other dimension was varied from 1 degree to 8 degrees. The threshold scotoma size that significantly (p < 0.05) attenuated the pattern visual evoked potential was a horizontal scotoma subtending 1 x 4 degrees and a vertical scotoma subtending 5 x 1 degree (vertical x horizontal). Meridional differences in cortical representation were not apparent to the larger scotoma series in which the fixed dimension subtended 3 degrees (3 x 2 degrees and 2 x 3 degrees). Further analysis of the data revealed that the apparent meridional difference for the 1 degree scotoma series was a function of data variability. The determinant of the PVEP amplitude was scotoma area, not orientation. Monocular and binocular threshold scotoma sizes were the same, which could be due to the level of binocular summation demonstrated by our subjects. PMID:7813381

  9. Subclinical hepatic encephalopathy: the diagnostic value of evoked potentials.

    PubMed

    Kullmann, F; Hollerbach, S; Holstege, A; Schölmerich, J

    1995-01-01

    Brainstem auditory (BAEPs) and somatosensory evoked potentials (SEPs) have been shown to be useful in detecting brainstem or cortical dysfunction in neurological diseases and in combination with other methods to diagnose brain death (37,38). These neurophysiological methods are simple and easy to perform. BAEPs and SEPs can even be easily recorded in intensive care units and guarantee a standardized examination. Moreover, these methods require no extensive patient cooperation and are not heavily influenced by learning effects. The role of BAEPs in the evaluation and diagnosis of hepatic encephalopathy is not clear. BAEPs are obviously strongly influenced by the etiology of liver disease and are normal in viral hepatitis, but prolonged in alcoholic liver disease, Wilson's disease or in hepatic coma (8,12). Unfortunately, BAEPs were not compared to psychometric tests. There was no clear-cut differentiation between various hepatic encephalopathy-gradings. At present, the use of BAEPs in the detection of subclinical hepatic encephalopathy cannot be recommended, whereas in comatose patients BAEPs can be useful as a prognostic marker and for follow-up examinations (12). Recently, Pozessere et al. (12) examined 13 comatose patients with advanced coma stages (Glasgow coma scale 5-10) and recorded unspecific changes in their EEG tracings. In all cases of hepatic coma and in one intoxicated patient they found prolongation of interpeak latencies. In addition, in this small study the interpeak latencies correlated well with the clinical outcome of the patients. Only two studies were performed using SEPs to detect neurophysiological alterations in hepatic encephalopathy (32,33). The design as well as the results of these studies are quite different. Despite the small number of patients (n = 10), the prolongation of late components in 50% of patients with hepatic encephalopathy stage 0 could be a promising result (32). The value of SEPs in detecting subclinical hepatic

  10. Short-Latency Median-Nerve Somatosensory-Evoked Potentials and Induced Gamma-Oscillations in Humans

    ERIC Educational Resources Information Center

    Fukuda, Miho; Nishida, Masaaki; Juhasz, Csaba; Muzik, Otto; Sood, Sandeep; Chugani, Harry T.; Asano, Eishi

    2008-01-01

    Recent studies have suggested that cortical gamma-oscillations are tightly linked with various forms of physiological activity. In the present study, the dynamic changes of intracranially recorded median-nerve somatosensory-evoked potentials (SEPs) and somatosensory-induced gamma-oscillations were animated on a three-dimensional MR image, and the…

  11. Facilitation of motor evoked potentials by somatosensory afferent stimulation.

    PubMed

    Deletis, V; Schild, J H; Berić, A; Dimitrijević, M R

    1992-10-01

    The effect of an electrically induced peripheral afferent volley upon electrical and magnetic motor evoked potentials (MEPs) from muscles of the upper and lower extremities was studied in 16 healthy volunteers. A standard conditioning-test (C-T) paradigm was employed whereby the test stimulus (transcranial electric or magnetic) was applied at random time intervals, from 10 msec prior to 90 msec after the conditioning stimulus (peripheral nerve stimulus). MEP amplitude facilitation was observed for the majority of the upper extremity muscles tested at two distinct periods, one occurring at short, and the other at long C-T intervals. This bimodal trend of MEP facilitation was found to be equally as prominent in the lower extremity muscles tested. The period of short C-T interval facilitation is consistent with modifications in the spinal excitability of the segmental motoneuron pool. On the other hand, the period of long C-T interval facilitation is suggested to be due to alterations in excitability of the motor cortex as a result of the arrival of the orthodromic sensory volley. Although most pronounced in muscles innervated by the nerve to which the conditioning stimulus was applied, this bimodal facilitatory effect was also observed in adjacent muscles not innervated by the stimulated nerve. Qualitatively, the conditioned MEPs from the upper and lower extremities responded similarly to both electrical and magnetic trans-cranial stimulation. In addition, our study demonstrates that the C-T paradigm has potential for use in the assessment of spinal and cortical sensorimotor integration by providing quantitative information which cannot be obtained through isolated assessment of sensory and/or motor pathways.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1385090

  12. Single-trial detection for intraoperative somatosensory evoked potentials monitoring.

    PubMed

    Hu, L; Zhang, Z G; Liu, H T; Luk, K D K; Hu, Y

    2015-12-01

    Abnormalities of somatosensory evoked potentials (SEPs) provide effective evidence for impairment of the somatosensory system, so that SEPs have been widely used in both clinical diagnosis and intraoperative neurophysiological monitoring. However, due to their low signal-to-noise ratio (SNR), SEPs are generally measured using ensemble averaging across hundreds of trials, thus unavoidably producing a tardiness of SEPs to the potential damages caused by surgical maneuvers and a loss of dynamical information of cortical processing related to somatosensory inputs. Here, we aimed to enhance the SNR of single-trial SEPs using Kalman filtering and time-frequency multiple linear regression (TF-MLR) and measure their single-trial parameters, both in the time domain and in the time-frequency domain. We first showed that, Kalman filtering and TF-MLR can effectively capture the single-trial SEP responses and provide accurate estimates of single-trial SEP parameters in the time domain and time-frequency domain, respectively. Furthermore, we identified significant correlations between the stimulus intensity and a set of indicative single-trial SEP parameters, including the correlation coefficient (between each single-trial SEPs and their average), P37 amplitude, N45 amplitude, P37-N45 amplitude, and phase value (at the zero-crossing points between P37 and N45). Finally, based on each indicative single-trial SEP parameter, we investigated the minimum number of trials required on a single-trial basis to suggest the existence of SEP responses, thus providing important information for fast SEP extraction in intraoperative monitoring. PMID:26557929

  13. Cerebral cortical neurons with activity linked to central neurogenic spontaneous and evoked elevations in cerebral blood flow

    NASA Technical Reports Server (NTRS)

    Golanov, E. V.; Reis, D. J.

    1996-01-01

    We recorded neurons in rat cerebral cortex with activity relating to the neurogenic elevations in regional cerebral blood flow (rCBF) coupled to stereotyped bursts of EEG activity, burst-cerebrovascular wave complexes, appearing spontaneously or evoked by electrical stimulation of rostral ventrolateral medulla (RVL) or fastigial nucleus (FN). Of 333 spontaneously active neurons only 15 (5%), in layers 5-6, consistently (P < 0.05, chi-square) increased their activity during the earliest potential of the complex, approximately 1.3 s before the rise of rCBF, and during the minutes-long elevation of rCBF elicited by 10 s of stimulation of RVL or FN. The results indicate the presence of a small population of neurons in deep cortical laminae whose activity correlates with neurogenic elevations of rCBF. These neurons may function to transduce afferent neuronal signals into vasodilation.

  14. A Comprehensive Review on Methodologies Employed for Visual Evoked Potentials

    PubMed Central

    Kothari, Ruchi; Bokariya, Pradeep; Singh, Smita; Singh, Ramji

    2016-01-01

    Visual information is fundamental to how we appreciate our environment and interact with others. The visual evoked potential (VEP) is among those evoked potentials that are the bioelectric signals generated in the striate and extrastriate cortex when the retina is stimulated with light which can be recorded from the scalp electrodes. In the current paper, we provide an overview of the various modalities, techniques, and methodologies which have been employed for visual evoked potentials over the years. In the first part of the paper, we cast a cursory glance on the historical aspect of evoked potentials. Then the growing clinical significance and advantages of VEPs in clinical disorders have been briefly described, followed by the discussion on the earlier and currently available methods for VEPs based on the studies in the past and recent times. Next, we mention the standards and protocols laid down by the authorized agencies. We then summarize the recently developed techniques for VEP. In the concluding section, we lay down prospective research directives related to fundamental and applied aspects of VEPs as well as offering perspectives for further research to stimulate inquiry into the role of visual evoked potentials in visual processing impairment related disorders. PMID:27034907

  15. Paying attention to orthography: a visual evoked potential study

    PubMed Central

    Herdman, Anthony T.; Takai, Osamu

    2013-01-01

    In adult readers, letters, and words are rapidly identified within visual networks to allow for efficient reading abilities. Neuroimaging studies of orthography have mostly used words and letter strings that recruit many hierarchical levels in reading. Understanding how single letters are processed could provide further insight into orthographic processing. The present study investigated orthographic processing using single letters and pseudoletters when adults were encouraged to pay attention to or away from orthographic features. We measured evoked potentials (EPs) to single letters and pseudoletters from adults while they performed an orthographic-discrimination task (letters vs. pseudoletters), a color-discrimination task (red vs. blue), and a target-detection task (respond to #1 and #2). Larger and later peaking N1 responses (~170 ms) and larger P2 responses (~250 ms) occurred to pseudoletters as compared to letters. This reflected greater visual processing for pseudoletters. Dipole analyses localized this effect to bilateral fusiform and inferior temporal cortices. Moreover, this letter-pseudoletter difference was not modulated by task and thus indicates that directing attention to or away from orthographic features did not affect early visual processing of single letters or pseudoletters within extrastriate regions. Paying attention to orthography or color as compared to disregarding the stimuli (target-detection task) elicited selection negativities at about 175 ms, which were followed by a classical N2-P3 complex. This indicated that the tasks sufficiently drew participant's attention to and away from the stimuli. Together these findings revealed that visual processing of single letters and pseudoletters, in adults, appeared to be sensory-contingent and independent of paying attention to stimulus features (e.g., orthography or color). PMID:23734115

  16. Arm movement maps evoked by cortical magnetic stimulation in a robotic environment

    PubMed Central

    Jones-Lush, Lauren M.; Judkins, Timothy N.; Wittenberg, George F.

    2009-01-01

    Many neurological diseases result in a severe inability to reach for which there is no proven therapy. Promising new interventions to address reaching rehabilitation using robotic training devices are currently under investigation in clinical trials but the neural mechanisms that underlie these interventions are not understood. Transcranial magnetic stimulation (TMS) may be used to probe such mechanisms quickly and non-invasively, by mapping muscle and movement representations in the primary motor cortex (M1). Here we investigate movement maps in healthy young subjects at rest using TMS in the robotic environment, with the goal of determining the range of TMS accessible movements, as a starting point for the study of cortical plasticity in combination with robotic therapy. We systematically stimulated the left motor cortex of 14 normal volunteers while the right hand and forearm rested in the cradle of a two degree-of-freedom planar rehabilitation robot (IMT). Maps were created by applying 10 stimuli at each of 9 locations (3 × 3 cm grid) centered on the M1 movement hotspot for each subject, defined as the stimulation location that elicited robot cradle movements of the greatest distance. TMS-evoked movement kinematics were measured by the robotic encoders and ranged in magnitude from 0–3 cm. Movement maps varied by subject and by location within a subject. However, movements were very consistent within a single stimulation location for a given subject. Movement vectors remained relatively constant (limited to <90 degree section of the planar field) within some subjects across the entire map, while others covered a wider range of directions. This may be due to individual differences in cortical physiology or anatomy, resulting in a practical limit to the areas that are TMS-accessible. This study provides a baseline inventory of possible TMS-evoked arm movements in the robotic reaching trainer, and thus may provide a real-time, non-invasive platform for

  17. Stimulator with arbitrary waveform for auditory evoked potentials

    NASA Astrophysics Data System (ADS)

    Martins, H. R.; Romão, M.; Plácido, D.; Provenzano, F.; Tierra-Criollo, C. J.

    2007-11-01

    The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.

  18. In vitro and in vivo measures of evoked excitatory and inhibitory conductance dynamics in sensory cortices.

    PubMed

    Monier, C; Fournier, J; Frégnac, Y

    2008-04-30

    In order to better understand the synaptic nature of the integration process operated by cortical neurons during sensory processing, it is necessary to devise quantitative methods which allow one to infer the level of conductance change evoked by the sensory stimulation and, consequently, the dynamics of the balance between excitation and inhibition. Such detailed measurements are required to characterize the static versus dynamic nature of the non-linear interactions triggered at the single cell level by sensory stimulus. This paper primarily reviews experimental data from our laboratory based on direct conductance measurements during whole-cell patch clamp recordings in two experimental preparations: (1) in vitro, during electrical stimulation in the visual cortex of the rat and (2) in vivo, during visual stimulation, in the primary visual cortex of the anaesthetized cat. Both studies demonstrate that shunting inhibition is expressed as well in vivo as in vitro. Our in vivo data reveals that a high level of diversity is observed in the degree of interaction (from linear to non-linear) and in the temporal interplay (from push-pull to synchronous) between stimulus-driven excitation (E) and inhibition (I). A detailed analysis of the E/I balance during evoked spike activity further shows that the firing strength results from a simultaneous decrease of evoked inhibition and increase of excitation. Secondary, the paper overviews the various computational methods used in the literature to assess conductance dynamics, measured in current clamp as well as in voltage clamp in different neocortical areas and species, and discuss the consistency of their estimations. PMID:18215425

  19. Effects of hypodynamia-hypokinesia on somatosensory evoked potentials in the rat.

    PubMed

    Canu, Marie Hélène; Langlet, Cécile; Dupont, Erwan; Falempin, Maurice

    2003-07-18

    The aim of this study was to determine if a prolonged period (7 or 14 days) of hypodynamia-hypokinesia (HH) affects the conduction of afferent input and the cortical and spinal responsiveness. Acute recordings of cortical and spinal somatosensory evoked potentials (SEPs) were performed after stimulation of the sciatic nerve in control rats and in rats submitted to 7 or 14 days of HH. HH was obtained by unloading the hindquarter. HH induced some subtle modifications in the SEP characteristics. Latency was increased for the spinal and cortical SEPs after 7 days of HH, and restored after 14 days of HH. A decrease in the amplitude was observed after 14 days of HH for the cortical SEP only. At the end of the experiment, the compound action potential of the sciatic nerve was recorded in vitro in order to evaluate the mean conduction velocity. Results indicate that the nerve velocity was reduced after 14 days of HH. The results also suggest that sensory conduction and/or cortical and spinal excitability are changed after HH. PMID:12834910

  20. Effect of epidural bupivacaine on somatosensory evoked potentials after dermatomal stimulation.

    PubMed

    Lund, C; Selmar, P; Hansen, O B; Hjortsø, N C; Kehlet, H

    1987-01-01

    The effect of lumbar epidural analgesia with plain bupivacaine, 0.5%, on early (less than 0.5 sec) somatosensory evoked potentials (SEP) to electrical stimulation of the T-10, L-1, and S-1 dermatomes and the posterior tibial nerve was examined in eight patients. A decrease of the cortical amplitude and an increase in latency were seen, most pronounced at the L-1 level, but with only minor effect on the S-1 dermatome. No correlation was found between segmental level of analgesia and decrease in amplitude of the evoked potentials. Thus despite clinically adequate surgical anesthesia, the neural pathways as assessed by SEP were incompletely blocked except at the L1 dermatome near the epidural injection site. PMID:3800017

  1. Visual evoked potential (VEP) measured by simultaneous 64-channel EEG and 3T fMRI.

    PubMed

    Bonmassar, G; Anami, K; Ives, J; Belliveau, J W

    1999-06-23

    We present the first simultaneous measurements of evoked potentials (EPs) and fMRI hemodynamic responses to visual stimulation. Visual evoked potentials (VEPs) were recorded both inside and outside the static 3T magnetic field, and during fMRI examination. We designed, constructed, and tested a non-magnetic 64-channel EEG recording cap. By using a large number of EEG channels it is possible to design a spatial filter capable of removing the artifact noise present when recording EEG/EPs within a strong magnetic field. We show that the designed spatial filter is capable of recovering the ballistocardiogram-contaminated original EEG signal. Isopotential plots of the electrode array recordings at the peak of the VEP response (approximately 100ms) correspond well with simultaneous fMRI observed activated areas of primary and secondary visual cortices. PMID:10501528

  2. [Evoked potentials in intracranial operations: current status and our experiences].

    PubMed

    Nau, H E; Hess, W; Pohlen, G; Marggraf, G; Rimpel, J

    1987-03-01

    Intraoperative neuromonitoring, especially evoked potential monitoring, has gained interest in recent years for both the anesthesiologist evaluating cerebral function and the neurosurgeon wishing to avoid neuronal lesions during intracranial operations. Before evoked potential monitoring can be introduced as a routine method of intraoperative management, experience with this method particularly in intensive care units, is imperative. We recorded evoked potentials with the Compact Four (Nicolet) and Basis 8000 (Schwarzer Picker International) computer systems. Preoperative derivations should be done with the same apparatus used intraoperatively and parameters of peri- and intraoperative derivations should not be changed. The patient's head must be fixed in a Mayfield clamp in order to avoid artefacts during trepanation. The possible artefacts due to apparatus, patient, or anesthesia are summarized in the tables. The derivations of evoked potentials should be supervised by a person who is not involved in the anesthesia or the surgical procedure; this condition may change in the future with full automatization of the recording technique and alarms. Good communication between surgeon, anesthesiologist, and neurophysiological assistant is a prerequisite. The modality is chosen in accordance with the affected neuronal system: visual-evoked potential (VEP) monitoring in the management of processes affecting the visual pathway, brain stem auditory-(BAER) and somatosensory-evoked potential (SSEP) monitoring in lesions affecting these pathways, in particular space-occupying lesions of the posterior fossa. VEP monitoring may be useful, but we observed alterations of the responses without changes in the level of anesthesia or manipulation of the visual pathways. In space-occupying processes of the cerebellopontine angle, BAER could not be developed in nearly all cases because the large underlying tumor had caused the disappearance of waves II-V. In these cases SSEP monitoring

  3. Brief wide-field photostimuli evoke and modulate oscillatory reverberating activity in cortical networks

    PubMed Central

    Pulizzi, Rocco; Musumeci, Gabriele; Van den Haute, Chris; Van De Vijver, Sebastiaan; Baekelandt, Veerle; Giugliano, Michele

    2016-01-01

    Cell assemblies manipulation by optogenetics is pivotal to advance neuroscience and neuroengineering. In in vivo applications, photostimulation often broadly addresses a population of cells simultaneously, leading to feed-forward and to reverberating responses in recurrent microcircuits. The former arise from direct activation of targets downstream, and are straightforward to interpret. The latter are consequence of feedback connectivity and may reflect a variety of time-scales and complex dynamical properties. We investigated wide-field photostimulation in cortical networks in vitro, employing substrate-integrated microelectrode arrays and long-term cultured neuronal networks. We characterized the effect of brief light pulses, while restricting the expression of channelrhodopsin to principal neurons. We evoked robust reverberating responses, oscillating in the physiological gamma frequency range, and found that such a frequency could be reliably manipulated varying the light pulse duration, not its intensity. By pharmacology, mathematical modelling, and intracellular recordings, we conclude that gamma oscillations likely emerge as in vivo from the excitatory-inhibitory interplay and that, unexpectedly, the light stimuli transiently facilitate excitatory synaptic transmission. Of relevance for in vitro models of (dys)functional cortical microcircuitry and in vivo manipulations of cell assemblies, we give for the first time evidence of network-level consequences of the alteration of synaptic physiology by optogenetics. PMID:27099182

  4. Human cortical activity evoked by the assignment of authenticity when viewing works of art.

    PubMed

    Huang, Mengfei; Bridge, Holly; Kemp, Martin J; Parker, Andrew J

    2011-01-01

    The expertise of others is a major social influence on our everyday decisions and actions. Many viewers of art, whether expert or naïve, are convinced that the full esthetic appreciation of an artwork depends upon the assurance that the work is genuine rather than fake. Rembrandt portraits provide an interesting image set for testing this idea, as there is a large number of them and recent scholarship has determined that quite a few fakes and copies exist. Use of this image set allowed us to separate the brain's response to images of genuine and fake pictures from the brain's response to external advice about the authenticity of the paintings. Using functional magnetic resonance imaging, viewing of artworks assigned as "copy," rather than "authentic," evoked stronger responses in frontopolar cortex (FPC), and right precuneus, regardless of whether the portrait was actually genuine. Advice about authenticity had no direct effect on the cortical visual areas responsive to the paintings, but there was a significant psycho-physiological interaction between the FPC and the lateral occipital area, which suggests that these visual areas may be modulated by FPC. We propose that the activation of brain networks rather than a single cortical area in this paradigm supports the art scholars' view that esthetic judgments are multi-faceted and multi-dimensional in nature. PMID:22164139

  5. Human Cortical Activity Evoked by the Assignment of Authenticity when Viewing Works of Art

    PubMed Central

    Huang, Mengfei; Bridge, Holly; Kemp, Martin J.; Parker, Andrew J.

    2011-01-01

    The expertise of others is a major social influence on our everyday decisions and actions. Many viewers of art, whether expert or naïve, are convinced that the full esthetic appreciation of an artwork depends upon the assurance that the work is genuine rather than fake. Rembrandt portraits provide an interesting image set for testing this idea, as there is a large number of them and recent scholarship has determined that quite a few fakes and copies exist. Use of this image set allowed us to separate the brain’s response to images of genuine and fake pictures from the brain’s response to external advice about the authenticity of the paintings. Using functional magnetic resonance imaging, viewing of artworks assigned as “copy,” rather than “authentic,” evoked stronger responses in frontopolar cortex (FPC), and right precuneus, regardless of whether the portrait was actually genuine. Advice about authenticity had no direct effect on the cortical visual areas responsive to the paintings, but there was a significant psycho-physiological interaction between the FPC and the lateral occipital area, which suggests that these visual areas may be modulated by FPC. We propose that the activation of brain networks rather than a single cortical area in this paradigm supports the art scholars’ view that esthetic judgments are multi-faceted and multi-dimensional in nature. PMID:22164139

  6. Brief wide-field photostimuli evoke and modulate oscillatory reverberating activity in cortical networks.

    PubMed

    Pulizzi, Rocco; Musumeci, Gabriele; Van den Haute, Chris; Van De Vijver, Sebastiaan; Baekelandt, Veerle; Giugliano, Michele

    2016-01-01

    Cell assemblies manipulation by optogenetics is pivotal to advance neuroscience and neuroengineering. In in vivo applications, photostimulation often broadly addresses a population of cells simultaneously, leading to feed-forward and to reverberating responses in recurrent microcircuits. The former arise from direct activation of targets downstream, and are straightforward to interpret. The latter are consequence of feedback connectivity and may reflect a variety of time-scales and complex dynamical properties. We investigated wide-field photostimulation in cortical networks in vitro, employing substrate-integrated microelectrode arrays and long-term cultured neuronal networks. We characterized the effect of brief light pulses, while restricting the expression of channelrhodopsin to principal neurons. We evoked robust reverberating responses, oscillating in the physiological gamma frequency range, and found that such a frequency could be reliably manipulated varying the light pulse duration, not its intensity. By pharmacology, mathematical modelling, and intracellular recordings, we conclude that gamma oscillations likely emerge as in vivo from the excitatory-inhibitory interplay and that, unexpectedly, the light stimuli transiently facilitate excitatory synaptic transmission. Of relevance for in vitro models of (dys)functional cortical microcircuitry and in vivo manipulations of cell assemblies, we give for the first time evidence of network-level consequences of the alteration of synaptic physiology by optogenetics. PMID:27099182

  7. EVOKED POTENTIALS, PHYSIOLOGICAL METHODS WITH HUMAN APPLICATIONS

    EPA Science Inventory

    A number of tests and test batteries have been developed and implemented for detecting potential neurotoxicity in humans. n some cases test results may suggest specific dysfunction. hile tests in laboratory animals are often used to project the potential for adverse health effect...

  8. [Clinical application of pain-related evoked potentials].

    PubMed

    Hansen, N; Obermann, M; Uçeyler, N; Zeller, D; Mueller, D; Yoon, M S; Reiners, K; Sommer, C; Katsarava, Z

    2012-02-01

    Pain-related evoked potentials (PREPs) represent a novel method for the evaluation of peripheral and central nociceptive pathways, e.g. in the diagnosis of small fiber neuropathy (SFN) or after therapeutic interventions for headache. Compared to contact heat-evoked and laser-evoked potentials, recording of PREPs is less stressful for the subjects and technically less demanding. The clinical usefulness of PREPs has been described for SFN associated with diabetes, HIV and hepatitis C infections as well as in headache and facial pain disorders. They have also been evaluated after interventional methods, such as direct current stimulation (tDCS). The article reviews and discusses the advantages and pitfalls of this technique in the context of recent clinical studies as compared to other paradigms of peripheral electrical stimulation and delineates perspectives and possible indications. PMID:22134376

  9. Recording and assessment of evoked potentials with electrode arrays.

    PubMed

    Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B

    2015-09-01

    In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution. PMID:25863691

  10. 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.

  11. The limits of tooth pulp evoked potentials for pain quantitation.

    PubMed

    Cruccu, G; Fornarelli, M; Inghilleri, M; Manfredi, M

    1983-09-01

    Tooth pulp evoked potentials (TPEPs) and subjective evaluation of painful dental stimuli have been recorded in healthy volunteers. The amplitude of TPEPs late components and the subjective rating have been studied in different psychological states, by the expectancy of pain with a placebo and by providing foreknowledge of stimulus timing with self-stimulation. The placebo induced a significant depression of TPEPs and pain sensation. The amplitude of TPEPs evoked by self-delivered stimuli was reduced but the subjective report remained unchanged. These results demonstrate that TPEPs are not a stable correlate of the pain perceived or of the painful input. PMID:6635002

  12. Human auditory evoked potentials. II - Effects of attention

    NASA Technical Reports Server (NTRS)

    Picton, T. W.; Hillyard, S. A.

    1974-01-01

    Attention directed toward auditory stimuli, in order to detect an occasional fainter 'signal' stimulus, caused a substantial increase in the N1 (83 msec) and P2 (161 msec) components of the auditory evoked potential without any change in preceding components. This evidence shows that human auditory attention is not mediated by a peripheral gating mechanism. The evoked response to the detected signal stimulus also contained a large P3 (450 msec) wave that was topographically distinct from the preceding components. This late positive wave could also be recorded in response to a detected omitted stimulus in a regular train and therefore seemed to index a stimulus-independent perceptual decision process.

  13. Magnetic motor evoked potentials in ponies.

    PubMed

    Mayhew, I G; Washbourne, J R

    1996-01-01

    Magnetic stimulation of motor pathways was used to effect motor unit action potential recordings from forelimb and hindlimb muscles in unanesthetized ponies. Motor pathway conduction velocities to the forelimb and hindlimb were determined to be 53.8 +/- 9.6 m/s-1 and 63.4 +/- 8.3 m/s-1, respectively. This noninvasive technique will enable more precise evaluation of motor deficits in clinical patients than is possible with the neurological examination. PMID:8884720

  14. SUPERIOR COLLICULUS LESIONS AND FLASH EVOKED POTENTIALS FROM RAT CORTEX

    EPA Science Inventory

    It is generally assumed that the primary response of the rat flash evoked potential (FEP) is activated by a retino-geniculate pathway, and that the second response reflects input to the cortex by way of the superior colliculus (SC) or other brainstem structures. In the present st...

  15. PATTERN REVERSAL VISUAL EVOKED POTENTIALS IN AWAKE RATS

    EPA Science Inventory

    A method for recording pattern reversal evoked potentials (PREPs) from awake restrained rats has been developed. The procedure of Onofrj et al. was modified to eliminate the need for anesthetic, thereby avoiding possible interactions of the anesthetic with other manipulations of ...

  16. Evaluation of Evoked Potentials to Dyadic Tones after Cochlear Implantation

    ERIC Educational Resources Information Center

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jancke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin

    2009-01-01

    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of…

  17. Evaluation of evoked potentials to dyadic tones after cochlear implantation.

    PubMed

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jäncke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin

    2009-07-01

    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of cochlear implant users (n = 12), which allowed detailed spatio-temporal evaluation of auditory evoked potentials by means of dipole source analysis. The present study examined hemispheric asymmetries of auditory evoked potentials to musical sounds in cochlear implant users to evaluate the effect of this type of implantation on neuronal activity. In particular, implant users were presented with two dyadic tonal intervals in an active oddball design and in a passive listening condition. Principally, the results show that independent component analysis is an efficient approach that enables the study of neurophysiological mechanisms of restored auditory function in cochlear implant users. Moreover, our data indicate altered hemispheric asymmetries for dyadic tone processing in implant users compared with listeners with normal hearing (n = 12). We conclude that the evaluation of auditory evoked potentials are of major relevance to understanding auditory cortex function after cochlear implantation and could be of substantial clinical value by indicating the maturation/reorganization of the auditory system after implantation. PMID:19293240

  18. Ocular vestibular evoked myogenic potentials in patients with acoustic neuroma.

    PubMed

    Piras, Gianluca; Brandolini, Cristina; Castellucci, Andrea; Modugno, Giovanni Carlo

    2013-02-01

    To assess the usefulness of vestibular testing in patients with acoustic neuroma, considering two main aspects: to compare diagnostic sensitivity of the current vestibular tests, especially considering ocular vestibular evoked myogenic potentials (OVEMPs) and to identify pre-operative localization of the tumor (inferior vestibular nerve vs. superior vestibular nerve) only with the help of vestibular electrophysiological data. Twenty-six patients with unilateral acoustic neuroma (mainly intracanalicular type) were studied with a full audio-vestibular test battery (pure tone and speech audiometry, caloric bithermal test, vibration-induced nystagmus test (VIN), cervical and OVEMPs). 18 patients (69 %) showed abnormal caloric responses. 12 patients (46.2 %) showed a pattern of VIN test suggestive of vestibular asymmetry. 16 patients (61.5 %) showed abnormal OVEMPs (12 only to AC, 4 both to AC and BC). 10 patients (38.5 %) showed abnormal cervical vestibular evoked myogenic potentials (5 both to AC and BC, 5 only to AC). In one case, results of vestibular evoked potentials and caloric test were confirmed by intra-operative and post-operative findings. Results of electrophysiological tests in AN patients could be helpful for planning the proper surgical approach, considering that sensitivity of every exam is quite low in intracanalicular lesion; clinical data allow a better interpretation of vestibular evoked myogenic potentials. PMID:22526579

  19. Multiple sclerosis: symptom equivalent to delayed visual evoked potential latency.

    PubMed

    Stenager, E; Jensen, K

    1990-10-01

    An investigation on the correlation between ability to read TV subtitles and the duration of visual evoked potential (VEP) latency in 14 patients with definite multiple sclerosis (MS), indicated that VEP latency in patients unable to read the TV subtitles was significantly delayed in comparison to that of patients who mastered this task. PMID:2275357

  20. COMPARABILITY OF RAT AND HUMAN VISUAL EVOKED POTENTIALS

    EPA Science Inventory

    A series of experiments was conducted to assess the comparability of physiological processes in rat and human visual systems. n the first set of experiments, transient visual evoked potentials (VEPs) were elicited by the onset of sine-wave gratings of various spatial frequencies....

  1. Cortical activity evoked by an acute painful tissue-damaging stimulus in healthy adult volunteers

    PubMed Central

    Williams, Gemma; Lee, Amy; Meek, Judith; Slater, Rebeccah; Olhede, Sofia; Fitzgerald, Maria

    2013-01-01

    Everyday painful experiences are usually single events accompanied by tissue damage, and yet most experimental studies of cutaneous nociceptive processing in the brain use repeated laser, thermal, or electrical stimulations that do not damage the skin. In this study the nociceptive activity in the brain evoked by tissue-damaging skin lance was analyzed with electroencephalography (EEG) in 20 healthy adult volunteers (13 men and 7 women) aged 21–40 yr. Time-frequency analysis of the evoked activity revealed a distinct late event-related vertex potential (lance event-related potential, LERP) at 100–300 ms consisting of a phase-locked energy increase between 1 and 20 Hz (delta-beta bands). A pairwise comparison between lance and sham control stimulation also revealed a period of ultralate stronger desynchronization after lance in the delta band (1–5 Hz). Skin application of mustard oil before lancing, which sensitizes a subpopulation of nociceptors expressing the cation channel TRPA1, did not affect the ultralate desynchronization but reduced the phase-locked energy increase in delta and beta bands, suggesting a central interaction between different modalities of nociceptive inputs. Verbal descriptor screening of individual pain experience revealed that lance pain is predominantly due to Aδ fiber activation, but when individuals describe lances as C fiber mediated, an ultralate delta band event-related desynchronization occurs in the brain-evoked activity. We conclude that pain evoked by acute tissue damage is associated with distinct Aδ and C fiber-mediated patterns of synchronization and desynchronization of EEG oscillations in the brain. PMID:23427303

  2. One year of musical training affects development of auditory cortical-evoked fields in young children.

    PubMed

    Fujioka, Takako; Ross, Bernhard; Kakigi, Ryusuke; Pantev, Christo; Trainor, Laurel J

    2006-10-01

    Auditory evoked responses to a violin tone and a noise-burst stimulus were recorded from 4- to 6-year-old children in four repeated measurements over a 1-year period using magnetoencephalography (MEG). Half of the subjects participated in musical lessons throughout the year; the other half had no music lessons. Auditory evoked magnetic fields showed prominent bilateral P100m, N250m, P320m and N450m peaks. Significant change in the peak latencies of all components except P100m was observed over time. Larger P100m and N450m amplitude as well as more rapid change of N250m amplitude and latency was associated with the violin rather than the noise stimuli. Larger P100m and P320m peak amplitudes in the left hemisphere than in the right are consistent with left-lateralized cortical development in this age group. A clear musical training effect was expressed in a larger and earlier N250m peak in the left hemisphere in response to the violin sound in musically trained children compared with untrained children. This difference coincided with pronounced morphological change in a time window between 100 and 400 ms, which was observed in musically trained children in response to violin stimuli only, whereas in untrained children a similar change was present regardless of stimulus type. This transition could be related to establishing a neural network associated with sound categorization and/or involuntary attention, which can be altered by music learning experience. PMID:16959812

  3. Effect of anesthesia on spontaneous activity and evoked potentials of the cerebellar cortex.

    PubMed

    Ordek, Gokhan; Groth, Jonathan D; Sahin, Mesut

    2012-01-01

    Cerebellum is a highly organized structure with a crystalline morphology that has always intrigued neuroscientists. Much of the cerebellar research has been conducted in anesthetized animals, particularly using ketamine and xylazine combination. It is not clear how the cerebellar cortical circuitry is affected by anesthesia. In this study, we have recorded spontaneous and evoked potentials from the cerebellar surface with chronically implanted, flexible-substrate, multi-electrode arrays. The frequency contents of the spontaneous activity suggest that ketamine/xylazine anesthesia suppresses most of the components except those below 30 Hz. This preliminary study also showed that multi channels of cerebellar cortical activity can be recorded using flexible multi-electrode arrays in behaving animals, which is very challenging task with single microelectrodes. PMID:23366022

  4. Peripheral electrical stimulation triggered by self-paced detection of motor intention enhances motor evoked potentials.

    PubMed

    Niazi, Imran Khan; Mrachacz-Kersting, Natalie; Jiang, Ning; Dremstrup, Kim; Farina, Dario

    2012-07-01

    This paper proposes the development and experimental tests of a self-paced asynchronous brain-computer interfacing (BCI) system that detects movement related cortical potentials (MRCPs) produced during motor imagination of ankle dorsiflexion and triggers peripheral electrical stimulations timed with the occurrence of MRCPs to induce corticospinal plasticity. MRCPs were detected online from EEG signals in eight healthy subjects with a true positive rate (TPR) of 67.15 ± 7.87% and false positive rate (FPR) of 22.05 ±9.07%. The excitability of the cortical projection to the target muscle (tibialis anterior) was assessed before and after the intervention through motor evoked potentials (MEP) using transcranial magnetic stimulation (TMS). The peak of the evoked potential significantly (P=0.02) increased after the BCI intervention by 53 ± 43% (relative to preintervention measure), although the spinal excitability (tested by stretch reflexes) did not change. These results demonstrate for the first time that it is possible to alter the corticospinal projections to the tibialis anterior muscle by using an asynchronous BCI system based on online motor imagination that triggered peripheral stimulation. This type of repetitive proprioceptive feedback training based on self-generated brain signal decoding may be a requirement for purposeful skill acquisition in intact humans and in the rehabilitation of persons with brain damage. PMID:22547461

  5. Transcranial magnetic stimulation and potential cortical and trigeminothalamic mechanisms in migraine

    PubMed Central

    Andreou, Anna P.; Holland, Philip R.; Akerman, Simon; Summ, Oliver; Fredrick, Joe

    2016-01-01

    A single pulse of transcranial magnetic stimulation has been shown to be effective for the acute treatment of migraine with and without aura. Here we aimed to investigate the potential mechanisms of action of transcranial magnetic stimulation, using a transcortical approach, in preclinical migraine models. We tested the susceptibility of cortical spreading depression, the experimental correlate of migraine aura, and further evaluated the response of spontaneous and evoked trigeminovascular activity of second order trigemontothalamic and third order thalamocortical neurons in rats. Single pulse transcranial magnetic stimulation significantly inhibited both mechanical and chemically-induced cortical spreading depression when administered immediately post-induction in rats, but not when administered preinduction, and when controlled by a sham stimulation. Additionally transcranial magnetic stimulation significantly inhibited the spontaneous and evoked firing rate of third order thalamocortical projection neurons, but not second order neurons in the trigeminocervical complex, suggesting a potential modulatory effect that may underlie its utility in migraine. In gyrencephalic cat cortices, when administered post-cortical spreading depression, transcranial magnetic stimulation blocked the propagation of cortical spreading depression in two of eight animals. These results are the first to demonstrate that cortical spreading depression can be blocked in vivo using single pulse transcranial magnetic stimulation and further highlight a novel thalamocortical modulatory capacity that may explain the efficacy of magnetic stimulation in the treatment of migraine with and without aura. PMID:27246325

  6. Transcranial magnetic stimulation and potential cortical and trigeminothalamic mechanisms in migraine.

    PubMed

    Andreou, Anna P; Holland, Philip R; Akerman, Simon; Summ, Oliver; Fredrick, Joe; Goadsby, Peter J

    2016-07-01

    A single pulse of transcranial magnetic stimulation has been shown to be effective for the acute treatment of migraine with and without aura. Here we aimed to investigate the potential mechanisms of action of transcranial magnetic stimulation, using a transcortical approach, in preclinical migraine models. We tested the susceptibility of cortical spreading depression, the experimental correlate of migraine aura, and further evaluated the response of spontaneous and evoked trigeminovascular activity of second order trigemontothalamic and third order thalamocortical neurons in rats. Single pulse transcranial magnetic stimulation significantly inhibited both mechanical and chemically-induced cortical spreading depression when administered immediately post-induction in rats, but not when administered preinduction, and when controlled by a sham stimulation. Additionally transcranial magnetic stimulation significantly inhibited the spontaneous and evoked firing rate of third order thalamocortical projection neurons, but not second order neurons in the trigeminocervical complex, suggesting a potential modulatory effect that may underlie its utility in migraine. In gyrencephalic cat cortices, when administered post-cortical spreading depression, transcranial magnetic stimulation blocked the propagation of cortical spreading depression in two of eight animals. These results are the first to demonstrate that cortical spreading depression can be blocked in vivo using single pulse transcranial magnetic stimulation and further highlight a novel thalamocortical modulatory capacity that may explain the efficacy of magnetic stimulation in the treatment of migraine with and without aura. PMID:27246325

  7. Evoked potential mapping of the rostral region by frameless navigation system in Mexican hairless pig.

    PubMed

    Saito, Toshiyuki; Uga, Minako; Tsuzuki, Daisuke; Yokota, Hidenori; Oguro, Keiji; Yamamoto, Tsuyoshi; Dan, Ippeita; Watanabe, Eiju

    2013-01-15

    There is an increasing need for a pig model for use in functional brain studies, but a system for determining precise stereotactic coordinates has yet to be developed. Thus, we devised a frameless navigation system for stereotactic positioning, and measured coordinates for the rostral region and the primary somatosensory cortex in the pig brain. Raw coordinates for somatic evoked potential recordings were obtained by passive optical tracking. The location was registered to a computed tomographic image in reference to four stable skull landmarks: the upper margin of each auditory meatus, the external occipital protuberance, and the point where the interfrontal suture crosses a line drawn between the two supraorbital foramina ("IF" point). The cortical position with the greatest response in evoked potential was mapped -51.0 ± 4.67 mm rostro-caudally, 9.1 ± 1.19 mm medio-laterally, and -8.8 ± 0.48 mm dorso-ventrally (means ± SD; n=3) to the IF point. These results show that frameless registration is useful for coordinate-based evoked-potential mapping of the rostral region of the Mexican hairless pig. PMID:23036661

  8. Cortical mapping of the optically evoked responses in channelrhodopsin-2 mouse model.

    PubMed

    Kim, Guk Bae; Cho, Jounhong Ryan; Shin, Hee-Sup; Choi, Jee Hyun

    2011-01-01

    Little is known about the information transfer properties of large-scale neural circuit in brain system. We applied optical deep brain stimulation to define the properties of information flow within a living brain assisted by channel rhodopsin-2 (ChR2) transgenic mice, of which neurons express the light-activated ion channel. We first characterized the responses of neuronal ensemble to the impinged light with respect to stimulation parameters by co-registering local field potentials with optical stimulation. Secondly, we applied recently developed polyimide based microarray for mouse electroencephalogram (EEG) to obtain the cortical responses with respect to deep brain stimulation. Particularly, the spatiotemporal cortical mapping with respect to deep brain stimulation of primary somatosensory cortex and hippocampus CA1 were presented in this article. PMID:22255892

  9. Reversible visual evoked potential abnormalities in uremic children.

    PubMed

    Ethier, Audrey-Anne; Lippé, Sarah; Mérouani, Aicha; Lassonde, Maryse; Saint-Amour, Dave

    2012-06-01

    In this case study, two cystinosis-related uremic children were followed at the Department of Nephrology, University of Montreal Hospital Center Sainte-Justine. Pattern-reversal visual evoked potentials were recorded at two time points, during dialysis treatment (time 1) and after renal transplant (time 2). Data were compared with those obtained from a control group (n = 6). The P1 component was selected and analyzed as the electrophysiologic marker of interest. At time 1, P1 latency was delayed, and P1 amplitude was reduced compared with control subjects. Both responses fell within normal range after kidney transplantation. These results indicate that renal failure and dialysis are associated with abnormal visual evoked potentials in children with chronic renal failure, but such alterations of visual processing are reversible after kidney transplant. PMID:22633636

  10. Membrane Potential Dynamics of Spontaneous and Visually Evoked Gamma Activity in V1 of Awake Mice

    PubMed Central

    Perrenoud, Quentin; Pennartz, Cyriel M. A.; Gentet, Luc J.

    2016-01-01

    Cortical gamma activity (30–80 Hz) is believed to play important functions in neural computation and arises from the interplay of parvalbumin-expressing interneurons (PV) and pyramidal cells (PYRs). However, the subthreshold dynamics underlying its emergence in the cortex of awake animals remain unclear. Here, we characterized the intracellular dynamics of PVs and PYRs during spontaneous and visually evoked gamma activity in layers 2/3 of V1 of awake mice using targeted patch-clamp recordings and synchronous local field potentials (LFPs). Strong gamma activity patterned in short bouts (one to three cycles), occurred when PVs and PYRs were depolarizing and entrained their membrane potential dynamics regardless of the presence of visual stimulation. PV firing phase locked unconditionally to gamma activity. However, PYRs only phase locked to visually evoked gamma bouts. Taken together, our results indicate that gamma activity corresponds to short pulses of correlated background synaptic activity synchronizing the output of cortical neurons depending on external sensory drive. PMID:26890123

  11. Visually evoked potentials in eccentrically and centrally fixing amblyopes.

    PubMed Central

    Srebro, R

    1984-01-01

    Visually evoked potentials to checkerboard pattern reversal were found to be nearly five times larger in eccentrically fixing amblyopic eyes than in centrally fixing amblyopic eyes when compared with the fellow non-amblyopic eye. The two groups of amblyopes had comparably poor visual acuity and differed in no other way save in their fixation behaviour. This suggests that at least two neurodevelopmental mechanisms subserve human amblyopia and that only one of these resembles the animal model of visual deprivation. PMID:6733071

  12. Establishing an evoked-potential vision-tracking system

    NASA Technical Reports Server (NTRS)

    Skidmore, Trent A.

    1991-01-01

    This paper presents experimental evidence to support the feasibility of an evoked-potential vision-tracking system. The topics discussed are stimulator construction, verification of the photic driving response in the electroencephalogram, a method for performing frequency separation, and a transient-analysis example. The final issue considered is that of object multiplicity (concurrent visual stimuli with different flashing rates). The paper concludes by discussing several applications currently under investigation.

  13. Influence of temperature on the sound-evoked vestibular potential.

    PubMed

    Wit, H P; Dijkgraaf, E

    1985-01-01

    The sound-evoked vestibular potential, measured with gross electrodes after fenestration of a lateral semicircular canal in pigeons, is delayed with respect to the acoustic stimulus. The influence of temperature of the vestibular system on this delay can most easily be explained by assuming chemically mediated transmission to take place between vestibular hair cells and their primary afferents. The possibility of electrotonic transmission, however, cannot be excluded. PMID:3878654

  14. Brainstem Auditory Evoked Potential Abnormalities in Type 2 Diabetes Mellitus

    PubMed Central

    Gupta, Sharat; Baweja, Pooja; Mittal, Shallu; Kumar, Avnish; Singh, Kamal D; Sharma, Raghuvansh

    2013-01-01

    Background: Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected. Aim: The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus. Materials and Methods: A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student's unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears. Results: The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally. Conclusion: Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies. PMID:23378959

  15. 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.

  16. Human auditory evoked potentials. I - Evaluation of components

    NASA Technical Reports Server (NTRS)

    Picton, T. W.; Hillyard, S. A.; Krausz, H. I.; Galambos, R.

    1974-01-01

    Fifteen distinct components can be identified in the scalp recorded average evoked potential to an abrupt auditory stimulus. The early components occurring in the first 8 msec after a stimulus represent the activation of the cochlea and the auditory nuclei of the brainstem. The middle latency components occurring between 8 and 50 msec after the stimulus probably represent activation of both auditory thalamus and cortex but can be seriously contaminated by concurrent scalp muscle reflex potentials. The longer latency components occurring between 50 and 300 msec after the stimulus are maximally recorded over fronto-central scalp regions and seem to represent widespread activation of frontal cortex.

  17. Mismatch Negativity and Adaptation Measures of the Late Auditory Evoked Potential in Cochlear Implant Users

    PubMed Central

    Zhang, Fawen; Hammer, Theresa; Banks, Holly-Lolan; Benson, Chelsea; Xiang, Jing; Fu, Qian-Jie

    2010-01-01

    A better understanding of the neural correlates of large variability in cochlear implant (CI) patients’ speech performance may allow us to find solutions to further improve CI benefits. The present study examined the mismatch negativity (MMN) and the adaptation of the late auditory evoked potential (LAEP) in 10 CI users. The speech syllable /da/ and 1-kHz tone burst were used to examine the LAEP adaptation. The amount of LAEP adaptation was calculated according to the averaged N1-P2 amplitude for the LAEPs evoked by the last 3 stimuli and the amplitude evoked by the first stimulus. For the MMN recordings, the standard stimulus (1-kHz tone) and the deviant stimulus (2-kHz tone) were presented in an oddball condition. Additionally, the deviants alone were presented in a control condition. The MMN was derived by subtracting the response to the deviants in the control condition from the oddball condition. Results showed that good CI performers displayed a more prominent LAEP adaptation than moderate-to-poor performers. Speech performance was significantly correlated to the amount of LAEP adaptation for the 1-kHz tone bursts. Good performers displayed large MMNs and moderate-to-poor performers had small or absent MMNs. The abnormal electrophysiological findings in moderate-to-poor performers suggest that long-term deafness may cause damage not only at the auditory cortical level, but also at the cognitive level. PMID:21129468

  18. Mismatch negativity and adaptation measures of the late auditory evoked potential in cochlear implant users.

    PubMed

    Zhang, Fawen; Hammer, Theresa; Banks, Holly-Lolan; Benson, Chelsea; Xiang, Jing; Fu, Qian-Jie

    2011-05-01

    A better understanding of the neural correlates of large variability in cochlear implant (CI) patients' speech performance may allow us to find solutions to further improve CI benefits. The present study examined the mismatch negativity (MMN) and the adaptation of the late auditory evoked potential (LAEP) in 10 CI users. The speech syllable /da/ and 1-kHz tone burst were used to examine the LAEP adaptation. The amount of LAEP adaptation was calculated according to the averaged N1-P2 amplitude for the LAEPs evoked by the last 3 stimuli and the amplitude evoked by the first stimulus. For the MMN recordings, the standard stimulus (1-kHz tone) and the deviant stimulus (2-kHz tone) were presented in an oddball condition. Additionally, the deviants alone were presented in a control condition. The MMN was derived by subtracting the response to the deviants in the control condition from the oddball condition. Results showed that good CI performers displayed a more prominent LAEP adaptation than moderate-to-poor performers. Speech performance was significantly correlated to the amount of LAEP adaptation for the 1-kHz tone bursts. Good performers displayed large MMNs and moderate-to-poor performers had small or absent MMNs. The abnormal electrophysiological findings in moderate-to-poor performers suggest that long-term deafness may cause damage not only at the auditory cortical level, but also at the cognitive level. PMID:21129468

  19. Decision-related cortical potentials during an auditory signal detection task with cued observation intervals

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Squires, N. K.; Hillyard, S. A.

    1975-01-01

    Cortical-evoked potentials were recorded from human subjects performing an auditory detection task with confidence rating responses. Unlike earlier studies that used similar procedures, the observation interval during which the auditory signal could occur was clearly marked by a visual cue light. By precisely defining the observation interval and, hence, synchronizing all perceptual decisions to the evoked potential averaging epoch, it was possible to demonstrate that high-confidence false alarms are accompanied by late-positive P3 components equivalent to those for equally confident hits. Moreover the hit and false alarm evoked potentials were found to covary similarly with variations in confidence rating and to have similar amplitude distributions over the scalp. In a second experiment, it was demonstrated that correct rejections can be associated with a P3 component larger than that for hits. Thus it was possible to show, within the signal detection paradigm, how the two major factors of decision confidence and expectancy are reflected in the P3 component of the cortical-evoked potential.

  20. The usefulness of EEG, exogenous evoked potentials, and cognitive evoked potentials in the acute stage of post-anoxic and post-traumatic coma.

    PubMed

    Guérit, J M

    2000-12-01

    Three-modality evoked potentials (TMEPs) have been used for several years in association with the EEG as a diagnostic and prognostic tool in acute anoxic or traumatic coma. Cognitive EPs have been recently introduced. EEG and cognitive EPs provide functional assessment of the cerebral cortex. TMEP parameters can be described by two indices: the index of global cortical function (IGCF) and the index of brainstem conduction (IBSC). Although it remains a unique tool for epilepsy assessment, the value of EEG is largely limited by its high sensitivity to the electrical environmental noise, its dependence on sedative drugs, and its inability to test the brainstem. Major TMEP alterations (absence of cortical activities more than 24 hours after the onset of post-anoxic coma, major pontine involvement in head trauma) are associated in all cases with an ominous prognosis (death or vegetative state). However, even if mild TMEP changes are associated with a good prognosis in 65% (post-anoxic coma) to 90% (head trauma) of cases, some patients never recover despite exogenous TMEPs that are only mildly altered in the acute stage. Thus, cognitive EPs can usefully complement exogenous EPs as a prognostic tool in coma. Indeed, even if the absence of cognitive EPs in comatose patients does not have any prognostic value, their presence implies a very high (more than 90%) probability of consciousness recovery. The major technical challenge for the future will be the development of reliable tools for continuous EEG and TMEP monitoring. PMID:11233678

  1. Wnt5a Evokes Cortical Axon Outgrowth and Repulsive Guidance by Tau Mediated Reorganization of Dynamic Microtubules

    PubMed Central

    Li, Li; Fothergill, Thomas; Hutchins, B Ian; Dent, Erik W; Kali, Katherine

    2014-01-01

    Wnt5a guides cortical axons in vivo by repulsion and in vitro evokes cortical axon outgrowth and repulsion by calcium signaling pathways. Here we examined the role of microtubule (MT) reorganization and dynamics in mediating effects of Wnt5a. Inhibiting MT dynamics with nocodazole and taxol abolished Wnt5a evoked axon outgrowth and repulsion of cultured hamster cortical neurons. EGFP-EB3 labeled dynamic MTs visualized in live cell imaging revealed that growth cone MTs align with the nascent axon. Wnt5a increased axon outgrowth by reorganization of dynamic MTs from a splayed to a bundled array oriented in the direction of axon extension, and Wnt5a gradients induced asymmetric redistribution of dynamic MTs toward the far side of the growth cone. Wnt5a gradients also evoked calcium transients that were highest on the far side of the growth cone. Calcium signaling and the reorganization of dynamic MTs could be linked by tau, a MT associated protein that stabilizes MTs. Tau is phosphorylated at the Ser 262 MT binding site by CaMKII, and is required for Wnt5a induced axon outgrowth and repulsive turning. Phosphorylation of tau at Ser262 is known to detach tau from MTs to increase their dynamics. Using transfection with tau constructs mutated at Ser262, we found that this site is required for the growth and guidance effects of Wnt5a by mediating reorganization of dynamic MTs in cortical growth cones. Moreover, CaMKII inhibition also prevents MT reorganization required for Wnt5a induced axon outgrowth, thus linking Wnt/calcium signaling to tau mediated MT reorganization during growth cone behaviors. © 2013 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc.Develop Neurobiol 74: 797–817, 2014 PMID:23818454

  2. Intraoperative monitoring of motor function by magnetic motor evoked potentials.

    PubMed

    Lee, W Y; Hou, W Y; Yang, L H; Lin, S M

    1995-03-01

    Under etomidate anesthesia, motor evoked potentials produced by magnetic stimulation were successfully recorded from 10 thenar muscles and 10 anterior tibial muscles of eight patients who had undergone surgery on the medulla oblongata and the cervical and thoracic spinal cords. Recordings taken before placing the neural tissue at risk were assessed for variability in amplitude and latency. The lower limit in amplitude was approximately one-third (25-43%) of the baseline. The latencies were more difficult to monitor than were the amplitudes. The latency variations were 2.56 +/- 0.50 milliseconds for the hand and 6.84 +/- 1.37 milliseconds for the leg. During surgery, the unilateral recordings of two patients were transiently lost but partially recovered after a pause in the operation. No obvious postoperative weaknesses in the corresponding limbs occurred. One patient, who showed a permanent loss of unilateral recording, had transient monoplegia with a complete recovery. None of the remaining five patients who had amplitudes larger than one-third of the baseline at the end of the operation had additional motor deficits. Our conclusions are that under etomidate anesthesia, the magnetic motor evoked potentials can be convenient and reliable monitors of motor function, that changes in the amplitude may be superior to those in the latency for intraoperative warning, that the criterion for potential neural damage under magnetic motor evoked potential monitoring might be an amplitude reduction of two-thirds of the control value, and that the magnetic stimulation seems to be more sensitive than the electrical stimulation in the monitoring of motor function and also allows more time and opportunities for the motor function to recover. PMID:7753349

  3. Chandelier cells control excessive cortical excitation: characteristics of whisker-evoked synaptic responses of layer 2/3 nonpyramidal and pyramidal neurons.

    PubMed

    Zhu, Yinghua; Stornetta, Ruth L; Zhu, J Julius

    2004-06-01

    Chandelier cells form inhibitory axo-axonic synapses on pyramidal neurons with their characteristic candlestick-like axonal terminals. The functional role of chandelier cells is still unclear, although the preferential loss of this cell type at epileptic loci suggests a role in epilepsy. Here we report an examination of whisker- and spontaneous activity-evoked responses in chandelier cells and other fast-spiking nonpyramidal neurons and regular-spiking pyramidal neurons in layer 2/3 of the barrel cortex. Fast-spiking nonpyramidal neurons, including chandelier cells, basket cells, neurogliaform cells, double bouquet cells, net basket cells, bitufted cells, and regular-spiking pyramidal neurons all respond to stimulation of multiple whiskers on the contralateral face. Whisker stimulation, however, evokes small, delayed EPSPs preceded by an earlier IPSP and no action potentials in chandelier cells, different from other nonpyramidal and pyramidal neurons. In addition, chandelier cells display a larger receptive field with lower acuity than other fast-spiking nonpyramidal neurons and pyramidal neurons. Notably, simultaneous dual whole-cell in vivo recordings show that chandelier cells, which rarely fire action potentials spontaneously, fire more robustly than other types of cortical neurons when the overall cortical excitation increases. Thus, chandelier cells may not process fast ascending sensory information but instead may be reserved to prevent excessive excitatory activity in neuronal networks. PMID:15175379

  4. Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children

    PubMed Central

    Campbell, Julia; Sharma, Anu

    2016-01-01

    Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5–7, 8–10, and 11–15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance. PMID:27445738

  5. Distinct Visual Evoked Potential Morphological Patterns for Apparent Motion Processing in School-Aged Children.

    PubMed

    Campbell, Julia; Sharma, Anu

    2016-01-01

    Measures of visual cortical development in children demonstrate high variability and inconsistency throughout the literature. This is partly due to the specificity of the visual system in processing certain features. It may then be advantageous to activate multiple cortical pathways in order to observe maturation of coinciding networks. Visual stimuli eliciting the percept of apparent motion and shape change is designed to simultaneously activate both dorsal and ventral visual streams. However, research has shown that such stimuli also elicit variable visual evoked potential (VEP) morphology in children. The aim of this study was to describe developmental changes in VEPs, including morphological patterns, and underlying visual cortical generators, elicited by apparent motion and shape change in school-aged children. Forty-one typically developing children underwent high-density EEG recordings in response to a continuously morphing, radially modulated, circle-star grating. VEPs were then compared across the age groups of 5-7, 8-10, and 11-15 years according to latency and amplitude. Current density reconstructions (CDR) were performed on VEP data in order to observe activated cortical regions. It was found that two distinct VEP morphological patterns occurred in each age group. However, there were no major developmental differences between the age groups according to each pattern. CDR further demonstrated consistent visual generators across age and pattern. These results describe two novel VEP morphological patterns in typically developing children, but with similar underlying cortical sources. The importance of these morphological patterns is discussed in terms of future studies and the investigation of a relationship to visual cognitive performance. PMID:27445738

  6. 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.

  7. Low-frequency rTMS inhibitory effects in the primary motor cortex: Insights from TMS-evoked potentials.

    PubMed

    Casula, Elias P; Tarantino, Vincenza; Basso, Demis; Arcara, Giorgio; Marino, Giuliana; Toffolo, Gianna Maria; Rothwell, John C; Bisiacchi, Patrizia S

    2014-09-01

    The neuromodulatory effects of repetitive transcranial magnetic stimulation (rTMS) have been mostly investigated by peripheral motor-evoked potentials (MEPs). New TMS-compatible EEG systems allow a direct investigation of the stimulation effects through the analysis of TMS-evoked potentials (TEPs). We investigated the effects of 1-Hz rTMS over the primary motor cortex (M1) of 15 healthy volunteers on TEP evoked by single pulse TMS over the same area. A second experiment in which rTMS was delivered over the primary visual cortex (V1) of 15 healthy volunteers was conducted to examine the spatial specificity of the effects. Single-pulse TMS evoked four main components: P30, N45, P60 and N100. M1-rTMS resulted in a significant decrease of MEP amplitude and in a significant increase of P60 and N100 amplitude. There was no effect after V1-rTMS. 1-Hz rTMS appears to increase the amount of inhibition following a TMS pulse, as demonstrated by the higher N100 and P60, which are thought to originate from GABAb-mediated inhibitory post-synaptic potentials. Our results confirm the reliability of the TMS-evoked N100 as a marker of cortical inhibition and provide insight into the neuromodulatory effects of 1-Hz rTMS. The present finding could be of relevance for therapeutic and diagnostic purposes. PMID:24793831

  8. The division of attention and the human auditory evoked potential

    NASA Technical Reports Server (NTRS)

    Hink, R. F.; Van Voorhis, S. T.; Hillyard, S. A.; Smith, T. S.

    1977-01-01

    The sensitivity of the scalp-recorded, auditory evoked potential to selective attention was examined while subjects responded to stimuli presented to one ear (focused attention) and to both ears (divided attention). The amplitude of the N1 component was found to be largest to stimuli in the ear upon which attention was to be focused, smallest to stimuli in the ear to be ignored, and intermediate to stimuli in both ears when attention was divided. The results are interpreted as supporting a capacity model of attention.

  9. Clinical application of vestibular evoked myogenic potential (VEMP).

    PubMed

    Murofushi, Toshihisa

    2016-08-01

    The author reviewed clinical aspects of vestibular evoked myogenic potentials (VEMPs). Now two types of VEMPs are available. The first one is cervical VEMP, which is recorded in the sternocleidomastoid muscle and predominantly reflects sacculo-collic reflex. The other is ocular VEMP, which is usually recorded below the lower eye lid and predominantly reflects utriculo-ocular reflex. VEMPs play important roles not only for assessment of common vestibular diseases but also for establishment of new clinical entities. Clinical application in Meniere's disease, vestibular neuritis, benign paroxysmal positional vertigo, vestibular migraine, idiopathic otolithic vertigo, and central vertigo/dizziness was reviewed. PMID:26791591

  10. Intraoperative Monitoring: Recent Advances in Motor Evoked Potentials.

    PubMed

    Koht, Antoun; Sloan, Tod B

    2016-09-01

    Advances in electrophysiological monitoring have improved the ability of surgeons to make decisions and minimize the risks of complications during surgery and interventional procedures when the central nervous system (CNS) is at risk. Individual techniques have become important for identifying or mapping the location and pathway of critical neural structures. These techniques are also used to monitor the progress of procedures to augment surgical and physiologic management so as to reduce the risk of CNS injury. Advances in motor evoked potentials have facilitated mapping and monitoring of the motor tracts in newer, more complex procedures. PMID:27521196

  11. Pattern-visual evoked potentials in thinner abusers.

    PubMed

    Poblano, A; Lope Huerta, M; Martínez, J M; Falcón, H D

    1996-01-01

    Organic solvents cause injury to lipids of neuronal and glial membranes. A well known characteristic of workers exposed to thinner is optic neuropathy. We decided to look for neurophysiologic signs of visual damage in patients identified as thinner abusers. Pattern reversal visual evoked potentials was performed on 34 thinner abuser patients and 30 controls. P-100 wave latency was found to be longer on abuser than control subjects. Results show the possibility of central alterations on thinner abusers despite absence of clinical symptoms. PMID:8987190

  12. Facilitation of magnetic motor evoked potentials during the mixed nerve silent period.

    PubMed

    Young, M S; Triggs, W J; Gerstle, G

    1995-11-01

    We studied motor neuron excitability during the mixed nerve silent period (MNSP) in a hand muscle using magnetic motor evoked potentials (MEPs) and F-waves. MEPs elicited between the V1 and V2 potentials of the MNSP were much larger than control MEPs elicited at rest, and were even comparable in size to control MEPs elicited during voluntary contraction. This facilitation of MEPs occurred without shortening of MEP latency, suggesting a supraspinal mechanism. MEPs were facilitated during the MNSP when elicited with a figure-8-shaped coil in a posterior-anterior orientation, but not when MEPs of the same size were elicited with the coil held in a lateral-medial orientation. F-waves elicited during the MNSP were variable between subjects, and not consistently different from control F-waves elicited at rest. Our findings may reflect increased cortical motor excitability during the MNSP, possibly related to activation of muscle afferents by mixed nerve stimulation. PMID:7565926

  13. Whole-scalp EEG mapping of somatosensory evoked potentials in macaque monkeys.

    PubMed

    Gindrat, Anne-Dominique; Quairiaux, Charles; Britz, Juliane; Brunet, Denis; Lanz, Florian; Michel, Christoph M; Rouiller, Eric M

    2015-07-01

    High-density scalp EEG recordings are widely used to study whole-brain neuronal networks in humans non-invasively. Here, we validate EEG mapping of somatosensory evoked potentials (SSEPs) in macaque monkeys (Macaca fascicularis) for the long-term investigation of large-scale neuronal networks and their reorganisation after lesions requiring a craniotomy. SSEPs were acquired from 33 scalp electrodes in five adult anaesthetized animals after electrical median or tibial nerve stimulation. SSEP scalp potential maps were identified by cluster analysis and identified in individual recordings. A distributed, linear inverse solution was used to estimate the intracortical sources of the scalp potentials. SSEPs were characterised by a sequence of components with unique scalp topographies. Source analysis confirmed that median nerve SSEP component maps were in accordance with the somatotopic organisation of the sensorimotor cortex. Most importantly, SSEP recordings were stable both intra- and interindividually. We aim to apply this method to the study of recovery and reorganisation of large-scale neuronal networks following a focal cortical lesion requiring a craniotomy. As a prerequisite, the present study demonstrated that a 300-mm(2) unilateral craniotomy over the sensorimotor cortex necessary to induce a cortical lesion, followed by bone flap repositioning, suture and gap plugging with calcium phosphate cement, did not induce major distortions of the SSEPs. In conclusion, SSEPs can be successfully and reproducibly recorded from high-density EEG caps in macaque monkeys before and after a craniotomy, opening new possibilities for the long-term follow-up of the cortical reorganisation of large-scale networks in macaque monkeys after a cortical lesion. PMID:24791748

  14. Serotonin potentiates sympathetic responses evoked by spinal NMDA

    PubMed Central

    Madden, Christopher J; Morrison, Shaun F

    2006-01-01

    In urethane–chloralose anaesthetized, neuromuscularly blocked, ventilated rats, we examined the effects on sympathetic outflow to brown adipose tissue (BAT) of separate and simultaneous spinal microinjections of NMDA and serotonin. Microinjection of NMDA (12 pmol) into the right T4 spinal intermediolateral nucleus (IML) immediately increased ipsilateral brown adipose tissue (BAT) sympathetic nerve activity (SNA; peak: +546% of control), BAT thermogenesis (+0.8°C) and heart rate (+53 beats min−1), whereas microinjection of a lower dose of NMDA (1.2 pmol) did not change any of the recorded variables. Microinjection of 5-hydroxytryptamine (5-HT, 2 nmol) into the T4 IML increased BAT SNA (peak: +342% of control) at a long latency (mean onset: 23min). The long latency 5-HT-evoked increase in BAT SNA was prevented by microinjection of methysergide (600 pmol) into the T4 IML. The increases in BAT SNA evoked by T4 IML microinjections of NMDA (12 pmol) were significantly potentiated (two to three times larger than the response to NMDA alone) following T4 IML microinjections of 5-HT (100 pmol to 2 nmol, but not 20 pmol). Also, microinjection of 5-HT (200 pmol) converted the subthreshold dose of NMDA (1.2 pmol) into an effective dose for increasing BAT SNA and heart rate. The 5-HT-mediated potentiation of the increase in BAT SNA evoked by microinjection of NMDA into the T4 IML was reversed by microinjection of methysergide (600 pmol) into the T4 IML. These results demonstrate that BAT SNA and thermogenesis can be driven by activation of spinal excitatory amino acid or 5-HT receptors and that concomitant activation of spinal NMDA and 5-HT receptors can act synergistically to markedly increase BAT SNA and thermogenesis. PMID:16973701

  15. One Year of Musical Training Affects Development of Auditory Cortical-Evoked Fields in Young Children

    ERIC Educational Resources Information Center

    Fujioka, Takako; Ross, Bernhard; Kakigi, Ryusuke; Pantev, Christo; Trainor, Laurel J.

    2006-01-01

    Auditory evoked responses to a violin tone and a noise-burst stimulus were recorded from 4- to 6-year-old children in four repeated measurements over a 1-year period using magnetoencephalography (MEG). Half of the subjects participated in musical lessons throughout the year; the other half had no music lessons. Auditory evoked magnetic fields…

  16. Laser-evoked cortical responses in freely-moving rats reflect the activation of C-fibre afferent pathways.

    PubMed

    Xia, X L; Peng, W W; Iannetti, G D; Hu, L

    2016-03-01

    The limited success of translating basic animal findings into effective clinical treatments of pain can be partly ascribed to the use of sub-optimal models. Murine models of pain often consist in recording (1) threshold responses (like the tail-flick reflex) elicited by (2) non-nociceptive specific inputs in (3) anaesthetized animals. The direct cortical recording of laser-evoked potentials (LEPs) elicited by stimuli of graded energies in freely-moving rodents avoids these three important pitfalls, and has thus the potential of improving such translation. Murine LEPs are classically reported to consist of two distinct components, reflecting the activity of Aδ- and C-fibre afferent pathways. However, we have recently demonstrated that the so-called "Aδ-LEPs" in fact reflect the activation of the auditory system by laser-generated ultrasounds. Here we used ongoing white noise to avoid the confound represented by the early auditory response, and thereby comprehensively characterized the physiological properties of C-fibre LEPs recorded directly from the exposed surface of the rat brain. Stimulus-response functions indicated that response amplitude is positively related to the stimulus energy, as well as to nocifensive behavioral score. When displayed using average reference, murine LEPs consist of three distinct deflections, whose polarity, order, and topography are surprisingly similar to human LEPs. The scalp topography of the early N1 wave is somatotopically-organized, likely reflecting the activity of the primary somatosensory cortex, while topographies of the later N2 and P2 waves are more centrally distributed. These results indicate that recording LEPs in freely-moving rats is a valid model to improve the translation of animal results to human physiology and pathophysiology. PMID:26747747

  17. Laser-evoked cortical responses in freely-moving rats reflect the activation of C-fibre afferent pathways

    PubMed Central

    Xia, X.L.; Peng, W.W.; Iannetti, G.D.; Hu, L.

    2016-01-01

    The limited success of translating basic animal findings into effective clinical treatments of pain can be partly ascribed to the use of sub-optimal models. Murine models of pain often consist in recording (1) threshold responses (like the tail-flick reflex) elicited by (2) non-nociceptive specific inputs in (3) anaesthetized animals. The direct cortical recording of laser-evoked potentials (LEPs) elicited by stimuli of graded energies in freely-moving rodents avoids these three important pitfalls, and has thus the potential of improving such translation. Murine LEPs are classically reported to consist of two distinct components, reflecting the activity of Aδ- and C-fibre afferent pathways. However, we have recently demonstrated that the so-called “Aδ-LEPs” in fact reflect the activation of the auditory system by laser-generated ultrasounds. Here we used ongoing white noise to avoid the confound represented by the early auditory response, and thereby comprehensively characterized the physiological properties of C-fibre LEPs recorded directly from the exposed surface of the rat brain. Stimulus–response functions indicated that response amplitude is positively related to the stimulus energy, as well as to nocifensive behavioral score. When displayed using average reference, murine LEPs consist of three distinct deflections, whose polarity, order, and topography are surprisingly similar to human LEPs. The scalp topography of the early N1 wave is somatotopically-organized, likely reflecting the activity of the primary somatosensory cortex, while topographies of the later N2 and P2 waves are more centrally distributed. These results indicate that recording LEPs in freely-moving rats is a valid model to improve the translation of animal results to human physiology and pathophysiology. PMID:26747747

  18. CORTICAL EVENT-RELATED POTENTIALS TO SPEECH SOUNDS IN 3- MONTH OLD BREAST AND FORMULA-FED INFANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies showing that infants can differentially process and discriminate speech stimuli have not considered the influence of diet as an experimental variable. To investigate this relationship, cortical auditory evoked potentials (ERPs) to syllables were recorded (128 electrodes) from 3 month old inf...

  19. K-means clustering method for auditory evoked potentials selection.

    PubMed

    Gourevitch, B; Le Bouquin-Jeannes, R

    2003-07-01

    Surface auditory evoked potentials are generally recorded using a headset of 32, 64 or 128 electrodes, but the quality of the responses is quite heterogeneous on the scalp surface. In some contexts, such as the analysis of auditory evoked potentials recorded in radio-frequency fields, the signal quality is essential, and it appears pertinent to consider only a limited number of electrodes. Therefore, before analysing signals influenced by radio-frequency fields, it is necessary to consider the preliminary step of selecting the channels where auditory activity is strong. This step is often realised by human visual selection and can take a considerable time. In this paper, a simple k-means clustering method is proposed, to select automatically the important channels, and the results are compared with traditional methods of selection. The method detected channels that showed a concordance rate of 86.5% with the visual selection (performed by five individuals) and gave the same final selection (only two extra electrodes in the automatic case). Moreover, the time needed for this automatic selection was 100 times less than that for the visual selection, and also human variability was avoided. PMID:12892361

  20. Middle Latency Auditory Evoked Potential (MLAEP) in Workers with and without Tinnitus who are Exposed to Occupational Noise

    PubMed Central

    dos Santos Filha, Valdete Alves Valentins; Samelli, Alessandra Giannella; Matas, Carla Gentile

    2015-01-01

    Background 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. Material/Methods 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. Results 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. Conclusions 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. PMID:26358094

  1. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    EPA Science Inventory

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats

    " NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo.

    " The pattern evok...

  2. Reversal of cocaine-evoked synaptic potentiation resets drug-induced adaptive behaviour.

    PubMed

    Pascoli, Vincent; Turiault, Marc; Lüscher, Christian

    2012-01-01

    Drug-evoked synaptic plasticity is observed at many synapses and may underlie behavioural adaptations in addiction. Mechanistic investigations start with the identification of the molecular drug targets. Cocaine, for example, exerts its reinforcing and early neuroadaptive effects by inhibiting the dopamine transporter, thus causing a strong increase in mesolimbic dopamine. Among the many signalling pathways subsequently engaged, phosphorylation of the extracellular signal-regulated kinase (ERK) in the nucleus accumbens is of particular interest because it has been implicated in NMDA-receptor and type 1 dopamine (D1)-receptor-dependent synaptic potentiation as well as in several behavioural adaptations. A causal link between drug-evoked plasticity at identified synapses and behavioural adaptations, however, is missing, and the benefits of restoring baseline transmission have yet to be demonstrated. Here we find that cocaine potentiates excitatory transmission in D1-receptor-expressing medium-sized spiny neurons (D1R-MSNs) in mice via ERK signalling with a time course that parallels locomotor sensitization. Depotentiation of cortical nucleus accumbens inputs by optogenetic stimulation in vivo efficiently restored normal transmission and abolished cocaine-induced locomotor sensitization. These findings establish synaptic potentiation selectively in D1R-MSNs as a mechanism underlying a core component of addiction, probably by creating an imbalance between distinct populations of MSNs in the nucleus accumbens. Our data also provide proof of principle that reversal of cocaine-evoked synaptic plasticity can treat behavioural alterations caused by addictive drugs and may inspire novel therapeutic approaches involving deep brain stimulation or transcranial magnetic stimulation. PMID:22158102

  3. [The significance of sex-linked differences for the assessment of somatosensory evoked potentials (author's transl)].

    PubMed

    Strenge, H; Hedderich, J; Tackmann, W

    1981-09-01

    In 45 healthy volunteers (22 males and 23 females with the same age structure) the peak latencies and inter-peak differences of the cervical and early cortical components of the somatosensory evoked potential were measured. The distribution of the values of the variables and their relationship with arm length were investigated both for the sample as a whole and for each sex separately. Significantly higher average values of the latencies and arm lengths were found in men. The correlations between arm length and latency had consistently higher values for the female sample. On the basis of these results it is concluded that a sufficient assessment of the latencies is only possible with the help of sex-specific normal values. PMID:6795015

  4. [Comparison of steady-state visually evoked potential evoked by different monochromatic light].

    PubMed

    Wu, Zhenghua; Yao, Dezhong

    2008-10-01

    The cone cell on the retina of human is the sensor of vision under illumination; it can be classified into three types: red cone cell, green cone cell, and blue cone cell. There is different property of absorbing light for each type of cone cell. In this work, a 10 Hz pulse was used to drive red, green and blue light emitting diodes respectively, and the different monochromatic light with the same luminance was obtained. The eyes of ten subjects were stimulated by different monochromatic light independently; an EGI system with 128 channels was used to record the steady-state visually evoked potential (SSVEP). After applying the fast fourier transform (FFT) to the SSVEP data, we found that the distribution of the neural network in the initial vision cortex activated by the output of the different-typed cone cell remained mainly identical, but there was some difference in intensity between the three types of network: the activity by blue light is the strongest one, that by red light is in the middle, and that by green light is the weakest one. PMID:19024438

  5. [Variations in the configuration of somatosensory evoked potentials following stimulation of the median nerve].

    PubMed

    Strenge, H

    1989-09-01

    The variants of waveform patterns of cervical and cortical somatosensory evoked potentials to median nerve stimulation at the wrist were analysed in 86 normal subjects aged 15 to 71 years. In cervical SEP recordings the components N13, N14 and the trough-shaped variant of P17 showed the highest short-term stability. Immediate changes of the amplitude proportions of subcomponents within the potential, i.e. a lack of uniformity in waveforms, have to be considered normal. Significant associations were found between the occurrence of components N14 and an arm length of more than 68 cm and between the appearance of a plateau configuration of P17 and an age of at least 40 years. Considering definite criteria the latency of P17 can be used as an additional reliable parameter. In cortical SEP recordings the combination of an initial V-shaped pattern and a following bifid W-configuration appeared as the most frequent waveform profile. All parts of the potential but the positive waves of the primary complex revealed a high intraindividual stability. PMID:2507276

  6. Topography of Synchronization of Somatosensory Evoked Potentials Elicited by Stimulation of the Sciatic Nerve in Rat

    PubMed Central

    Qu, Xuefeng; Yan, Jiaqing; Li, Xiaoli; Zhang, Peixun; Liu, Xianzeng

    2016-01-01

    Purpose: Traditionally, the topography of somatosensory evoked potentials (SEPs) is generated based on amplitude and latency. However, this operation focuses on the physical morphology and field potential-power, so it suffers from difficulties in performing identification in an objective manner. In this study, measurement of the synchronization of SEPs is proposed as a method to explore brain functional networks as well as the plasticity after peripheral nerve injury. Method: SEPs elicited by unilateral sciatic nerve stimulation in twelve adult male Sprague-Dawley (SD) rats in the normal group were compared with SEPs evoked after unilateral sciatic nerve hemisection in four peripheral nerve injured SD rats. The characterization of synchronized networks from SEPs was conducted using equal-time correlation, correlation matrix analysis, and comparison to randomized surrogate data. Eigenvalues of the correlation matrix were used to identify the clusters of functionally synchronized neuronal activity, and the participation index (PI) was calculated to indicate the involvement of each channel in the cluster. The PI value at the knee point of the PI histogram was used as a threshold to demarcate the cortical boundary. Results: Ten out of the twelve normal rats showed only one synchronized brain network. The remaining two normal rats showed one strong and one weak network. In the peripheral nerve injured group, only one synchronized brain network was found in each rat. In the normal group, all network shapes appear regular and the network is largely contained in the posterior cortex. In the injured group, the network shapes appear irregular, the network extends anteriorly and posteriorly, and the network area is significantly larger. There are considerable individual variations in the shape and location of the network after peripheral nerve injury. Conclusion: The proposed method can detect functional brain networks. Compared to the results of the traditional SEP

  7. 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

  8. P3 event-related evoked potential in young adults.

    PubMed

    Tandon, O P

    1990-07-01

    P3 component of event related potential reflects memory and decision making processes. It has been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects. Scalp P3 was elicited in 24 male neurologically and audiologically normal young subjects of 17-20 years (Av. 17.7) of age. Standard auditory 'Oddball' paradigm involving simple discrimination task of concentrating on infrequent (target) stimulus and ignoring frequent (non target) stimulus was employed. Evoked response trials of discriminating 32 target stimuli out of 160 total presented (20% target and 80% non target randomly) were replicated and analysed by computer. Latency of P3 as 305 +/- 18.4 msec and amplitude 6.5 +/- 2.1 uv are being reported which are comparable with age and sex matched subjects of western world. PMID:2286422

  9. Auditory Evoked Potential Response and Hearing Loss: A Review

    PubMed Central

    Paulraj, M. P; Subramaniam, Kamalraj; Yaccob, Sazali Bin; Adom, Abdul H. Bin; Hema, C. R

    2015-01-01

    Hypoacusis is the most prevalent sensory disability in the world and consequently, it can lead to impede speech in human beings. One best approach to tackle this issue is to conduct early and effective hearing screening test using Electroencephalogram (EEG). EEG based hearing threshold level determination is most suitable for persons who lack verbal communication and behavioral response to sound stimulation. Auditory evoked potential (AEP) is a type of EEG signal emanated from the brain scalp by an acoustical stimulus. The goal of this review is to assess the current state of knowledge in estimating the hearing threshold levels based on AEP response. AEP response reflects the auditory ability level of an individual. An intelligent hearing perception level system enables to examine and determine the functional integrity of the auditory system. Systematic evaluation of EEG based hearing perception level system predicting the hearing loss in newborns, infants and multiple handicaps will be a priority of interest for future research. PMID:25893012

  10. The visual evoked potential in acute primary angle closure glaucoma.

    PubMed Central

    Mitchell, K. W.; Wood, C. M.; Howe, J. W.; Church, W. H.; Smith, G. T.; Spencer, S. R.

    1989-01-01

    Visual evoked potentials (VEPs) were elicited from 29 patients who had experienced a previous attack of acute primary angle closure glaucoma. The VEPs were shown to be abnormal in at least one of the measures (latency, amplitude, contrast threshold, or slope) in 72.4% of affected eyes, whereas only 41.4% indicated obvious optic nerve damage. It is notable that 48.1% of fellow eyes with no (known) history of acute pressure rise also showed some form of VEP abnormality. The possible pathophysiological mechanisms operating in both affected and fellow eyes are discussed. It is concluded that, despite the presence of possible artefactual influences, the results probably reflect the presence of primary angle closure glaucoma. PMID:2751978

  11. Intercostal somatosensory-evoked potentials. A new technique.

    PubMed

    Dreyfuss, P; Dumitru, D; Prewitt-Buchanan, L

    1993-06-01

    Presently, there are few electrodiagnostic medicine techniques to evaluate lesions affecting the thoracic nerve roots or spinal cord. A new electrophysiologic technique to assess these structures, intercostal somatosensory-evoked potentials (SEPs), is described. Thirty neurologically normal subjects were used in this investigation to generate intercostal SEPs. Bilateral intercostal SEPs were easily elicited after stimulation of the third intercostal nerves just lateral to the sternum anteriorly. Intercostal SEPs were also easily elicited from the fifth, seventh and ninth intercostal nerves along the anterior axillary line bilaterally. Intercostal SEPs are not only easily and painlessly obtained, but are specific for individual spinal levels. This SEP method will provide the clinician with another neural stimulation procedure to assist in the diagnosis of both central and peripheral thoracic neural compromise. PMID:8512676

  12. Source localization of auditory evoked potentials after cochlear implantation.

    PubMed

    Debener, Stefan; Hine, Jemma; Bleeck, Stefan; Eyles, Julie

    2008-01-01

    Little is known about how the auditory cortex adapts to artificial input as provided by a cochlear implant (CI). We report the case of a 71-year-old profoundly deaf man, who has successfully used a unilateral CI for 4 years. Independent component analysis (ICA) of 61-channel EEG recordings could separate CI-related artifacts from auditory-evoked potentials (AEPs), even though it was the perfectly time-locked CI stimulation that caused the AEPs. AEP dipole source localization revealed contralaterally larger amplitudes in the P1-N1 range, similar to normal hearing individuals. In contrast to normal hearing individuals, the man with the CI showed a 20-ms shorter N1 latency ipsilaterally. We conclude that ICA allows the detailed study of AEPs in CI users. PMID:17910729

  13. 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.

  14. Conscious Wireless Electroretinogram and Visual Evoked Potentials in Rats

    PubMed Central

    He, Zheng; Dang, Trung M.; Vingrys, Algis J.; Fish, Rebecca L.; Gurrell, Rachel; Brain, Phil; Bui, Bang V.

    2013-01-01

    The electroretinogram (ERG, retina) and visual evoked potential (VEP, brain) are widely used in vivo tools assaying the integrity of the visual pathway. Current recordings in preclinical models are conducted under anesthesia, which alters neural physiology and contaminates responses. We describe a conscious wireless ERG and VEP recording platform in rats. Using a novel surgical technique to chronically implant electrodes subconjunctivally on the eye and epidurally over the visual cortex, we are able to record stable and repeatable conscious ERG and VEP signals over at least 1 month. We show that the use of anaesthetics, necessary for conventional ERG and VEP measurements, alters electrophysiology recordings. Conscious visual electrophysiology improves the viability of longitudinal studies by eliminating complications associated with repeated anaesthesia. It will also enable uncontaminated assessment of drug effects, allowing the eye to be used as an effective biomarker of the central nervous system. PMID:24069276

  15. Visual Evoked Potentials: Normative Values and Gender Differences

    PubMed Central

    Sharma, Ruby; Singh, K.D.; Kumar, Avnish

    2015-01-01

    Introduction Visual evoked potentials (VEP) are used to assess the visual pathways through the optic nerves and brain. A normal VEP response to a pattern-reversal stimulus is a positive mid occipital peak that occurs at a mean latency of 100 ms. VEP may be affected by variety of physiological factors including age, sex, visual acuity and pupillary size. Aims and Objectives The present study was performed on healthy medical students to determine the normative values and to investigate the effect of sex and anthropometric parameters on visual evoked potentials. Materials and Methods The study was conducted on 100 healthy medical students of Government Medical College, Patiala in the age group of 17-20 years, in which there were 50 males and 50 females. The anthropometric parameters including age, height, weight, BMI, BSA and Head circumference were recorded in all the subjects. VEP was recorded with a PC based, 2 channel, RMS EMG EP mark II machine and standard silver-silver chloride disc electrodes. A VEP monitor displaying checker board was used to give the pattern reversal stimulus. The VEP parameters recorded were latencies to N70, P100 and N155 waves, and peak to peak amplitude of P100 wave. Results Our results showed that the latencies of N70, P100 and N155 waves were significantly longer in males as compared to females. The amplitude of P100 wave was higher in females in both left and right eye as compared to males. No significant correlation was found between VEP parameters and head circumference in both male and female subjects in our study. Conclusion Gender is an important variable affecting the VEP. The exact reason of gender difference is not clear, but it may be related to anatomical or endocrinal differences in the two sexes. PMID:26393122

  16. Spatio-temporal source modeling of evoked potentials to acoustic and cochlear implant stimulation.

    PubMed

    Ponton, C W; Don, M; Waring, M D; Eggermont, J J; Masuda, A

    1993-01-01

    Spatio-temporal source modeling (STSM) of event-related potentials was used to estimate the loci and characteristics of cortical activity evoked by acoustic stimulation in normal hearing subjects and by electrical stimulation in cochlear implant (CI) subjects. In both groups of subjects, source solutions obtained for the N1/P2 complex were located in the superior half of the temporal lobe in the head model. Results indicate that it may be possible to determine whether stimulation of different implant channels activates different regions of cochleotopically organized auditory cortex. Auditory system activation can be assessed further by examining the characteristics of the source wave forms. For example, subjects whose cochlear implants provided auditory sensations and normal hearing subjects had similar source activity. In contrast, a subject in whom implant activation evoked eyelid movements exhibited different source wave forms. STSM analysis may provide an electrophysiological technique for guiding rehabilitation programs based on the capabilities of the individual implant user and for disentangling the complex response patterns to electrical stimulation of the brain. PMID:7694834

  17. Evoked potentials and contingent negative variation during treatment of multiple sclerosis with spinal cord stimulation.

    PubMed Central

    Sedgwick, E M; Illis, L S; Tallis, R C; Thornton, A R; Abraham, P; El-Negamy, E; Docherty, T B; Soar, J S; Spencer, S C; Taylor, F M

    1980-01-01

    Cervical somatosensory evoked potentials, brainstem evoked potentials, visual evoked potentials, and the cerebral contingent negative variation were recorded in patients with definite multiple sclerosis before, during, and after spinal cord stimulation. Improvements were seen in the cervical somatosensory and brainstem evoked potentials but neither the visual evoked potential nor the contingent negative variation changed in association with spinal cord stimulation. The results indicate that spinal cord stimulation acts at spinal and brainstem levels and that the clinical improvements seen in patients are caused by an action at these levels rather than by any cerebral arousal or motivational effect. The evoked potentials were not useful in predicting which patients were likely to respond to stimulation. PMID:7354352

  18. Multimodality evoked potentials and electrically elicited blink reflex in optic neuritis.

    PubMed

    Tackmann, W; Ettlin, T; Strenge, H

    1982-01-01

    Pattern shift visual evoked potentials, brain stem auditory evoked potentials, spinal and scalp recorded somatosensory evoked potentials, and electrically elicited blink reflexes were investigated in 32 patients with isolated optic neuritis. Eleven patients were shown to have one additional lesion in the central nervous system outside the optic nerve. Therefore, cases with optic neuritis of unknown origin should be considered as possible cases of multiple sclerosis. PMID:6181223

  19. Effect of imperceptible vibratory noise applied to wrist skin on fingertip touch evoked potentials – an EEG study

    PubMed Central

    Seo, Na Jin; Lakshminarayanan, Kishor; Bonilha, Leonardo; Lauer, Abigail W; Schmit, Brian D

    2015-01-01

    Random vibration applied to skin can change the sense of touch. Specifically, low amplitude white-noise vibration can improve fingertip touch perception. In fact, fingertip touch sensation can improve even when imperceptible random vibration is applied to other remote upper extremity areas such as wrist, dorsum of the hand, or forearm. As such, vibration can be used to manipulate sensory feedback and improve dexterity, particularly during neurological rehabilitation. Nonetheless, the neurological bases for remote vibration enhanced sensory feedback are yet poorly understood. This study examined how imperceptible random vibration applied to the wrist changes cortical activity for fingertip sensation. We measured somatosensory evoked potentials to assess peak-to-peak response to light touch of the index fingertip with applied wrist vibration versus without. We observed increased peak-to-peak somatosensory evoked potentials with wrist vibration, especially with increased amplitude of the later component for the somatosensory, motor, and premotor cortex with wrist vibration. These findings corroborate an enhanced cortical-level sensory response motivated by vibration. It is possible that the cortical modulation observed here is the result of the establishment of transient networks for improved perception. PMID:26603457

  20. Is the motion system relatively spared in amblyopia? Evidence from cortical evoked responses.

    PubMed

    Kubová, Z; Kuba, M; Juran, J; Blakemore, C

    1996-01-01

    Visual evoked potentials (VEPs) produced by pattern reversal were compared with those elicited by onset of motion in 37 amblyopic children (20 with anisometropic amblyopia, seven with strabismic amblyopia and 10 with both anisometropia and strabismus). The amplitudes and peak latencies of the main P1 peak in the pattern-reversal VEP and of the motion-specific N2 peak in the motion-onset VEP through the amblyopic eye were compared with those through the normal fellow eye. Regardless of the type of amblyopia, the amplitude of the pattern-reversal VEP for full-field stimulation was significantly smaller and its latency significantly longer through the amblyopic eye (P < 0.001). In contrast, neither the amplitudes nor the latencies of the N2 motion-onset VEPs differed significantly between amblyopic and non-amblyopic eyes. For pattern-reversal VEPs through the amblyopic eyes, the extent to which amplitude was reduced and latency prolonged correlated well with the reduction of visual acuity, whereas the amplitudes and latencies of motion-onset VEPs did not vary with visual acuity. Even for stimuli restricted to the central visual field (5 or 2 deg diameter) or to the peripheral field (excluding the central 5 deg), motion-onset responses were indistinguishable through the two eyes, while pattern-reversal responses always differed significantly in amplitude. These results suggest that the source of motion-onset VEPs (probably an extrastriate motion-sensitive area) is less affected in amblyopia than that of pattern-reversal VEPs (probably the striate cortex). The motion pathway, presumably deriving mainly from the magnocellular layers of the lateral geniculate nucleus, may be relatively spared in amblyopia. PMID:8746252

  1. Do resting brain dynamics predict oddball evoked-potential?

    PubMed Central

    2011-01-01

    Background The oddball paradigm is widely applied to the investigation of cognitive function in neuroscience and in neuropsychiatry. Whether cortical oscillation in the resting state can predict the elicited oddball event-related potential (ERP) is still not clear. This study explored the relationship between resting electroencephalography (EEG) and oddball ERPs. The regional powers of 18 electrodes across delta, theta, alpha and beta frequencies were correlated with the amplitude and latency of N1, P2, N2 and P3 components of oddball ERPs. A multivariate analysis based on partial least squares (PLS) was applied to further examine the spatial pattern revealed by multiple correlations. Results Higher synchronization in the resting state, especially at the alpha spectrum, is associated with higher neural responsiveness and faster neural propagation, as indicated by the higher amplitude change of N1/N2 and shorter latency of P2. None of the resting quantitative EEG indices predict P3 latency and amplitude. The PLS analysis confirms that the resting cortical dynamics which explains N1/N2 amplitude and P2 latency does not show regional specificity, indicating a global property of the brain. Conclusions This study differs from previous approaches by relating dynamics in the resting state to neural responsiveness in the activation state. Our analyses suggest that the neural characteristics carried by resting brain dynamics modulate the earlier/automatic stage of target detection. PMID:22114868

  2. EEG and evoked potentials in a series of 21 patients with lissencephaly type I.

    PubMed

    de Rijk-van Andel, J F; Arts, W F; de Weerd, A W

    1992-02-01

    Twenty-one Dutch patients were the subject of an extensive study into lissencephaly type I. One hundred and fourteen EEG's of these patients were studied. The EEG's were compared to 52 EEG's recorded from 21 patients with an atypical cortical dysplasia and to a control group consisting of 882 EEG's recorded from 823 patients for various reasons. The EEG's in the lissencephaly patients showed the following patterns significantly more often: (a) generalized fast activity (8-18/s) with an amplitude higher than 50 microV, (c) sharp- and slow-wave complexes with an amplitude higher than 500 microV, (d) an alternating pattern consisting of bursts of sharp waves alternating with periods of electrocerebral depression. Ninety-five percent of the lissencephaly patients showed pattern (a) or (c) or both compared to only 5% of the patients with an atypical cortical dysplasia and 0.4% in the controls. The SSEP's recorded in ten patients after stimulation of the median nerve were abnormal in all. EEG and evoked potentials appear to be valuable examinations in the (differential) diagnosis of lissencephaly type I. PMID:1565217

  3. Skill-specific changes in somatosensory-evoked potentials and reaction times in baseball players.

    PubMed

    Yamashiro, Koya; Sato, Daisuke; Onishi, Hideaki; Yoshida, Takuya; Horiuchi, Yoko; Nakazawa, Sho; Maruyama, Atsuo

    2013-03-01

    Athletic training is known to induce neuroplastic alterations in specific somatosensory circuits, which are reflected by changes in short-latency somatosensory-evoked potentials (SEPs). The aim of this study is to clarify whether specific training in athletes affects the long-latency SEPs related to information processing of stimulation. The long-latency SEPs P100 and N140 were recorded at midline cortical electrode positions (Fz, Cz, and Pz) in response to stimulation of the index finger of the dominant hand in fifteen baseball players (baseball group) and in fifteen athletes in sports such as swimming, track and field events, and soccer (sports group) that do not require fine somatosensory discrimination or motor control of the hand. The long-latency SEPs were measured under a passive condition (no response required) and a reaction time (RT) condition in which subjects were instructed to rapidly push a button in response to stimulus presentation. The peak P100 and peak N140 latencies and RT were significantly shorter in the baseball group than the sports group. Moreover, there were significant positive correlations between RT and both the peak P100 and the peak N140 latencies. Specific athletic training regimens that involve the hand may induce neuroplastic alterations in the cortical hand representation areas playing a vital role in rapid sensory processing and initiation of motor responses. PMID:23224701

  4. 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

  5. The frequency modulated auditory evoked response (FMAER), a technical advance for study of childhood language disorders: cortical source localization and selected case studies

    PubMed Central

    2013-01-01

    Background Language comprehension requires decoding of complex, rapidly changing speech streams. Detecting changes of frequency modulation (FM) within speech is hypothesized as essential for accurate phoneme detection, and thus, for spoken word comprehension. Despite past demonstration of FM auditory evoked response (FMAER) utility in language disorder investigations, it is seldom utilized clinically. This report's purpose is to facilitate clinical use by explaining analytic pitfalls, demonstrating sites of cortical origin, and illustrating potential utility. Results FMAERs collected from children with language disorders, including Developmental Dysphasia, Landau-Kleffner syndrome (LKS), and autism spectrum disorder (ASD) and also normal controls - utilizing multi-channel reference-free recordings assisted by discrete source analysis - provided demonstratrions of cortical origin and examples of clinical utility. Recordings from inpatient epileptics with indwelling cortical electrodes provided direct assessment of FMAER origin. The FMAER is shown to normally arise from bilateral posterior superior temporal gyri and immediate temporal lobe surround. Childhood language disorders associated with prominent receptive deficits demonstrate absent left or bilateral FMAER temporal lobe responses. When receptive language is spared, the FMAER may remain present bilaterally. Analyses based upon mastoid or ear reference electrodes are shown to result in erroneous conclusions. Serial FMAER studies may dynamically track status of underlying language processing in LKS. FMAERs in ASD with language impairment may be normal or abnormal. Cortical FMAERs can locate language cortex when conventional cortical stimulation does not. Conclusion The FMAER measures the processing by the superior temporal gyri and adjacent cortex of rapid frequency modulation within an auditory stream. Clinical disorders associated with receptive deficits are shown to demonstrate absent left or bilateral

  6. Visual evoked potential guidance for posteroventral pallidotomy in Parkinson's disease.

    PubMed

    Yokoyama, T; Sugiyama, K; Nishizawa, S; Ryu, H; Hinokuma, K; Yamamoto, S; Endoh, M; Ohta, S; Yokota, N; Uemura, K

    1997-03-01

    Visual evoked potentials (VEPs) to photic stimulation of the eyes were used to identify the optic tract and thus determine the location of the globus pallidus internus (GPi) in eight patients with Parkinson's disease who then underwent posteroventral pallidotomy. Distinct waves appeared at 1 or 2 mm below the target (4 to 5 mm below the intercommissural line) and the amplitude significantly increased at 5 or 6 mm below, strongly suggesting that the electrode was in contact with the optic tract. In the medio-lateral direction, potentials were successively recorded in an area of 4 to 8 mm length, indicating the width of the optic tract. The trajectory at the mid point showed the most significant potentials which suggested the center of the optic tract. The site of the first lesion was placed 0 to 2 mm lateral to this trajectory and 5 mm above the point at which the amplitudes of responses increased. The actual lesion site significantly differed from the tentative target in a medio-lateral direction by 1 to 5 mm (mean 3.0 +/- 1.5 mm, n = 6). The Unified Parkinson's Disease Rating Scale score significantly improved and magnetic resonance imaging taken 2 or 3 weeks after the operation showed a lesion within the GPi in each patient. Recording of VEPs greatly facilitates accurate determination of the GPi. PMID:9095626

  7. Laser Evoked Potentials in Early and Presymptomatic Huntington's Disease.

    PubMed

    de Tommaso, Marina; Franco, Giovanni; Ricci, Katia; Montemurno, Anna; Sciruicchio, Vittorio

    2016-01-01

    Pain was rarely studied in Huntington's disease (HD). We presently aimed to extend our previous study on pain pathways functions by laser evoked potentials (LEPs) to a larger cohort of early unmedicated HD patients and a small group of presymptomatic HD (PHD) subjects. Forty-two early HD patients, 10 PHD patients, and 64 controls were submitted to LEPs by right-hand stimulation. Two series of 30 laser stimuli were delivered, and artifact-free responses were averaged. The N1, N2, and P2 latencies were significantly increased and the N2P2 amplitude significantly reduced in HD patients compared to controls. In the HD group, the LEPs abnormalities correlated with functional decline. PHD subjects showed a slight and insignificant increase in LEPs latencies, which was inversely correlated with the possible age of HD clinical onset. Data of the present study seem to suggest that the functional state of nociceptive pathways as assessed by LEPs may be a potential biomarker of disease onset and progression. The assessment of pain symptoms in premanifest and manifest HD may also open a new scenario in terms of subtle disturbances of pain processing, which may have a role in the global burden of the disease. PMID:27087746

  8. Anesthetic effects on motor evoked potentials in dogs.

    PubMed

    Glassman, S D; Shields, C B; Linden, R D; Zhang, Y P; Nixon, A R; Johnson, J R

    1993-06-15

    The effects of the various anesthetic agents on the production of transcranial magnetic motor evoked potentials (tcMMEP) were studied in a canine model. Pre-anesthetic baseline tcMMEPs demonstrated consistency in onset latency measurements and variability in measurement of peak-to-peak amplitudes. Changes in tcMMEPs were evaluated following the individual administrations of sodium pentothal, etomidate, halothane, fentanyl, and ketamine. For induction of anesthesia, etomidate was compatible with tcMMEP production, whereas sodium pentothal resulted in loss of hindlimb potentials for a period of 45 minutes. For maintenance of anesthesia, halothane was incompatible with the measurement of tcMMEPs. Fentanyl administration was consistent with the recording of reliable tcMMEPs, with consistent onset latencies but widely variable peak-to-peak amplitudes. Ketamine was compatible with stable and reproducible tcMMEP production. The results of this study suggest that anesthetic agents have a predictable and consistent effect on tcMMEP responses. PMID:8367777

  9. Optic nerve evoked potentials elicited by electrical stimulation.

    PubMed

    Kikuchi, Yasuhiro; Sasaki, Tatsuya; Matsumoto, Masato; Oikawa, Tomoyoshi; Itakura, Takeshi; Kodama, Namio

    2005-07-01

    This study investigated whether the optic nerve evoked potential (ONEP) elicited by electrical stimulation of the optic nerve can serve as a reliable intraoperative indicator of visual function. In the experimental study, two silver-ball stimulating electrodes were placed on the dog optic nerve adjacent to the apex of the orbit and one recording electrode was placed on the optic nerve near the chiasm. The nerve was stimulated with 0.1 to 10 mA rectangular pulses. Stable and reproducible ONEPs were obtained. The ONEPs were not influenced by electromyographic potentials and were recorded more clearly on the optic nerve than on the surrounding tissue. Stepwise incremental transection of the thickness of the nerve resulted in incremental amplitude reduction proportional to the transected area. No response was recorded after complete sectioning of the nerve. In the clinical study, recordings were obtained from 15 patients after craniotomy to treat parasellar tumors or cerebral aneurysms. Reproducible ONEPs were recorded intraoperatively from the electrode placed on the optic nerve near the chiasm in 14 of 15 patients. In the remaining patient, the ONEP, recorded only after tumor removal because the optic nerve was stretched and extremely thin, was remarkably small and the patient developed unilateral blindness postoperatively. These experimental and clinical results suggest the possibility of intraoperative monitoring of visual function in patients undergoing craniotomy for the treatment of lesions near the optic nerve. PMID:16041180

  10. 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. PMID:25649969

  11. Laser Evoked Potentials in Early and Presymptomatic Huntington's Disease

    PubMed Central

    de Tommaso, Marina; Franco, Giovanni; Ricci, Katia; Montemurno, Anna; Sciruicchio, Vittorio

    2016-01-01

    Pain was rarely studied in Huntington's disease (HD). We presently aimed to extend our previous study on pain pathways functions by laser evoked potentials (LEPs) to a larger cohort of early unmedicated HD patients and a small group of presymptomatic HD (PHD) subjects. Forty-two early HD patients, 10 PHD patients, and 64 controls were submitted to LEPs by right-hand stimulation. Two series of 30 laser stimuli were delivered, and artifact-free responses were averaged. The N1, N2, and P2 latencies were significantly increased and the N2P2 amplitude significantly reduced in HD patients compared to controls. In the HD group, the LEPs abnormalities correlated with functional decline. PHD subjects showed a slight and insignificant increase in LEPs latencies, which was inversely correlated with the possible age of HD clinical onset. Data of the present study seem to suggest that the functional state of nociceptive pathways as assessed by LEPs may be a potential biomarker of disease onset and progression. The assessment of pain symptoms in premanifest and manifest HD may also open a new scenario in terms of subtle disturbances of pain processing, which may have a role in the global burden of the disease. PMID:27087746

  12. Topography and homogeneity of monkey V1 studied through subdurally recorded pattern-evoked potentials.

    PubMed

    Dagnelie, G; Spekreijse, H; van Dijk, B

    1989-12-01

    Using small checkerboard stimulus fields, we have recorded visually evoked potentials (VEPs) in an alert rhesus monkey from an array of 35 electrodes chronically implanted between dura and arachnoid to study mass neuronal activity in striate and peristriate visual cortex. Although the principal purpose of this work was to study in detail cortical mapping in this particular animal for future intracortical recordings, we report here the usefulness of our approach for the non-invasive study of cortical processing, in particular of cortical magnification and receptive-field properties over the central 6 degrees of the visual field. The striate and extrastriate components in the pattern onset VEP both have a double negative-going waveform, with N-P-N peak latencies of 75-100-135 ms and 90-115-160 ms, respectively, for small element sizes and moderate contrasts; latencies may be 5 ms shorter for large element sizes and high contrast. We found little activity at electrode locations over visual areas beyond V2. The waveforms and timing permit some careful speculation concerning intracortical processing and VEP generation. The complex logarithmic form of the retinotopical projection provides a satisfactory model for our data, if a value of 1-1.2 degrees is used for the offset parameter a. Our data suggest that the most abundant receptive-field size in foveal striate cortex has a center diameter of 12'. This size remains constant up to 2 degrees eccentricity, and increases only slowly up to 4 degrees. The smallest receptive-field sizes seem to be independent of eccentricity throughout the central 4 degrees of V1, with a value of 4-8', in agreement with single-cell data reported by Dow et al. (1981) and Van Essen et al. (1984). PMID:2487121

  13. Visual and somatosensory evoked potentials and F-wave latency measurements in hereditary neuropathy with liability to pressure palsies.

    PubMed

    Strenge, H; Soyka, D; Tackmann, W

    1982-01-01

    Pattern shift visual evoked potentials (VEPs), cervical and cortical somatosensory evoked responses (SEPs) and motor conduction velocities studied by F-wave latency measurements were investigated in two family members with hereditary neuropathy with liability to pressure palsies (HN-PP). In both cases in VEPs and SEP conduction times N13-N20 were normal. A bilateral pathological increase of latencies of early SEP components, N9-N13 transit times and F-wave latencies revealed a lesion in the proximal parts of the median nerves close to the spinal cord in the older patient. These abnormalities emphasize the close relationship of HN-PP with hereditary polyradiculopathy (Mayer 1975). PMID:6174708

  14. Auditory Evoked Potentials with Different Speech Stimuli: a Comparison and Standardization of Values

    PubMed Central

    Didoné, Dayane Domeneghini; Oppitz, Sheila Jacques; Folgearini, Jordana; Biaggio, Eliara Pinto Vieira; Garcia, Michele Vargas

    2016-01-01

    Introduction Long Latency Auditory Evoked Potentials (LLAEP) with speech sounds has been the subject of research, as these stimuli would be ideal to check individualś detection and discrimination. Objective The objective of this study is to compare and describe the values of latency and amplitude of cortical potentials for speech stimuli in adults with normal hearing. Methods The sample population included 30 normal hearing individuals aged between 18 and 32 years old with ontological disease and auditory processing. All participants underwent LLAEP search using pairs of speech stimuli (/ba/ x /ga/, /ba/ x /da/, and /ba/ x /di/. The authors studied the LLAEP using binaural stimuli at an intensity of 75dBNPS. In total, they used 300 stimuli were used (∼60 rare and 240 frequent) to obtain the LLAEP. Individuals received guidance to count the rare stimuli. The authors analyzed latencies of potential P1, N1, P2, N2, and P300, as well as the ampleness of P300. Results The mean age of the group was approximately 23 years. The averages of cortical potentials vary according to different speech stimuli. The N2 latency was greater for /ba/ x /di/ and P300 latency was greater for /ba/ x /ga/. Considering the overall average amplitude, it ranged from 5.35 and 7.35uV for different speech stimuli. Conclusion It was possible to obtain the values of latency and amplitude for different speech stimuli. Furthermore, the N2 component showed higher latency with the / ba / x / di / stimulus and P300 for /ba/ x / ga /. PMID:27096012

  15. Brainstem Evoked Potential in Newly Diagnosed Patients of Subclinical Hypothyroidism

    PubMed Central

    Sharma, Kirti; Behera, Joshil Kumar; Kumar, Naresh; Sood, Sushma; Madan, Harnam Singh; Das, Sibadatta

    2015-01-01

    Background: Hypothyroidism is known to be associated with impairment of hearing. The hearing impairment may be conductive, sensorineural, or mixed. Aims: The aim is to assess the auditory pathway by brainstem auditory evoked potentials (BAEPs) in newly diagnosed patients of subclinical hypothyroidism and healthy sex- and age-matched controls. Materials and Methods: The study included 25 healthy sex- and age-matched controls (Group I) and 25 patients of newly diagnosed subclinical hypothyroidism (Group II). The recording was taken by using RMS EMG EP MK2 equipment. The unpaired Student's t-test was used and a P value <0.05 was considered significant. Results: Wave V of right ear BAEP in group II was prolonged (6 ± 0.62 ms) compared to group I (5.49 ± 0.26 ms), and wave V of left ear BAEP in group II was prolonged (5.84 ± 0.57 ms) compared to group I (5.47 ± 0.35 ms). There was no significant coefficient of correlation between wave V and inter-peak latency (IPL) I-V compared to thyroid-stimulating hormone (TSH) levels of both the ears. Conclusion: The prolongation of wave V in BAEPs of both ears suggests that the central auditory pathway is affected significantly in subclinical hypothyroid patients. PMID:25973399

  16. Flash visual evoked potentials in diurnal birds of prey.

    PubMed

    Dondi, Maurizio; Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris's Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function. PMID:27547536

  17. Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

    PubMed

    Nachtigall, Paul E; Supin, Alexander Y; Amundin, Mats; Röken, Bengt; Møller, Thorsten; Mooney, T Aran; Taylor, Kristen A; Yuen, Michelle

    2007-04-01

    While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution. PMID:17371910

  18. Transdiagnostic psychiatric symptoms related to visual evoked potential abnormalities.

    PubMed

    Bedwell, Jeffrey S; Butler, Pamela D; Chan, Chi C; Trachik, Benjamin J

    2015-12-15

    Visual processing abnormalities have been reported across a range of psychotic and mood disorders, but are typically examined within a particular disorder. The current study used a novel transdiagnostic approach to examine diagnostic classes, clinician-rated current symptoms, and self-reported personality traits in relation to visual processing abnormalities. We examined transient visual-evoked potentials (VEPs) from 48 adults (56% female), representing a wide range of psychotic and mood disorders, as well as individuals with no history of psychiatric disorder. Stimuli were low contrast check arrays presented on green and red backgrounds. Pairwise comparisons between individuals with schizophrenia-spectrum disorders (SSD), chronic mood disorders (CMD), and nonpsychiatric controls (NC) revealed no overall differences for either P1 or N1 amplitude. However, there was a significant interaction with the color background in which the NC group showed a significant increase in P1 amplitude to the red, vs. green, background, while the SSD group showed no change. This was related to an increase in social anhedonia and general negative symptoms. Stepwise regressions across the entire sample revealed that individuals with greater apathy and/or eccentric behavior had a reduced P1 amplitude. These relationships provide clues for uncovering the underlying causal pathology for these transdiagnostic symptoms. PMID:26412383

  19. Flash visual evoked potentials in diurnal birds of prey

    PubMed Central

    Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris’s Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function. PMID:27547536

  20. The brainstem auditory evoked potential in infants and children.

    PubMed

    Goldie, W D

    1992-07-01

    The brainstem auditory evoked potential (BAEP) is a neurophysiological study that provides functional information about the auditory system and brainstem. It provides information that is different from any other form of evaluation. This report tries to summarize technical and clinical information that will make the BAEP more meaningful for the practicing technologist and clinician. Attention is focused on the BAEP as it is used in infants and children, starting with a brief review of auditory physiology, then progressing to normative data, clinical utility, physical setup, preparing the patient, comments on technique, and comments on interpretation. This is not an exhaustive review of the topic, and many important elements of clinical utility had to be left out. This review tries to focus on recent references and on practical issues, and it relies on the experience and opinions of the author. Emphasis has been placed on the use of the BAEP by the neurologist, but an attempt has been made to acknowledge the importance of audiology and otolaryngology as well as speech and language science. Particular emphasis has been placed on the use of the BAEP in assessing the premature infant and young infant at risk for neurological and audiological injury. An enormous amount of published data is available in the literature, and much of it had to be left out of this review. However, the reader is encouraged to develop an enthusiasm for the BAEP and to further explore the broad range of its clinical uses. PMID:1517406

  1. ISCEV standard for clinical visual evoked potentials: (2016 update).

    PubMed

    Odom, J Vernon; Bach, Michael; Brigell, Mitchell; Holder, Graham E; McCulloch, Daphne L; Mizota, Atsushi; Tormene, Alma Patrizia

    2016-08-01

    Visual evoked potentials (VEPs) can provide important diagnostic information regarding the functional integrity of the visual system. This document updates the ISCEV standard for clinical VEP testing and supersedes the 2009 standard. The main changes in this revision are the acknowledgment that pattern stimuli can be produced using a variety of technologies with an emphasis on the need for manufacturers to ensure that there is no luminance change during pattern reversal or pattern onset/offset. The document is also edited to bring the VEP standard into closer harmony with other ISCEV standards. The ISCEV standard VEP is based on a subset of stimulus and recording conditions that provide core clinical information and can be performed by most clinical electrophysiology laboratories throughout the world. These are: (1) Pattern-reversal VEPs elicited by checkerboard stimuli with large 1 degree (°) and small 0.25° checks. (2) Pattern onset/offset VEPs elicited by checkerboard stimuli with large 1° and small 0.25° checks. (3) Flash VEPs elicited by a flash (brief luminance increment) which subtends a visual field of at least 20°. The ISCEV standard VEP protocols are defined for a single recording channel with a midline occipital active electrode. These protocols are intended for assessment of the eye and/or optic nerves anterior to the optic chiasm. Extended, multi-channel protocols are required to evaluate postchiasmal lesions. PMID:27443562

  2. Electroretinogram and visual-evoked potential measurements in sheep.

    PubMed Central

    Strain, G M; Claxton, M S; Prescott-Mathews, J S; LaPhand, D J

    1991-01-01

    Electroretinogram (ERG) and visual-evoked potential (VEP) recordings were taken from ten Suffolk-cross sheep. Stimuli for VEP were 1.5 flashes of white light/s; ERG stimuli were single flashes. The ERG measurements of the a and b wave latencies and a-to-b amplitude were measured between the lower eyelid and the vertex, with ground on the nuchal crest. The VEP after monocular stimulation were measured between the nuchal crest and the interorbital line, with ground on the vertex. Measurements consisted of the latencies to seven alternating positive and negative peaks P1, N1, P2, N2, P3, N3 and P4, and six amplitudes, P1-N1, N1-P2, P2-N2, N2-P3, P3-N3 and N3-P4. Average latencies for the a and b waves were 13.6 and 28.2 ms; the mean ab amplitude was 131.68 microV. Average latencies for the seven VEP peaks were 35.0, 43.1, 52.8, 64.1, 74.5, 90.4 and 112.2 ms. Mean amplitudes ranged from 3.90 to 8.29 microV. PMID:1884277

  3. Excitotoxic insults to the optic nerve alter visual evoked potentials.

    PubMed

    Soto, A; Pérez-Samartín, A L; Etxebarria, E; Matute, C

    2004-01-01

    Excitotoxic oligodendroglial death is one of the mechanisms which has been proposed to underlie demyelinating diseases of the CNS. We describe here functional consequences of excitotoxic lesions to the rabbit optic nerve by studying the visual evoked potentials (VEPs) measured in the visual cortex. Nerves were slowly infused with the excitotoxin kainate a subcutaneously implanted osmotic pump which delivered the toxin through a cannula onto the optic nerve. Records of VEPs were obtained before pump implantation and at 1, 3 and 7 days post-implantation, and weekly evaluated thereafter for up to 4 months. We observed that the VEPs generated by light stimuli progressively changed in both amplitude and profile after the lesion as well as in comparison to those generated in control animals infused with vehicle. Histological examination of the damage caused by the excitotoxic insult showed that large areas of the optic nerve were demyelinated and their axons distorted. These observations were confirmed and extended by immunohistochemical analyses using markers to neurofilaments, myelin basic protein and the oligodendrocyte marker APC. The results of the present paper indicate that the consequences of excitotoxicity in the optic nerve share functional and morphological alterations which are found in demyelinating disorders. In addition, this experimental paradigm may be useful to evaluate the functional recovery of demyelinated optic nerves following various repair strategies. PMID:14698751

  4. Contrast Sensitivity versus Visual Evoked Potentials in Multiple Sclerosis

    PubMed Central

    Shandiz, Javad Heravian; Nourian, Abbas; Hossaini, Mercedeh Bahr; Moghaddam, Hadi Ostadi; yekta, Abbas-Ali; Sharifzadeh, Laleh; Marouzi, Parviz

    2010-01-01

    Purpose To compare the Cambridge contrast sensitivity (CS) test and visual evoked potentials (VEP) in detecting visual impairment in a population of visually symptomatic and asymptomatic patients affected by clinically definite multiple sclerosis (MS). Methods Fifty patients (100 eyes) presenting with MS and 25 healthy subjects (50 eyes) with normal corrected visual acuity were included in this study. CS was determined using the Cambridge Low Contrast Grating test and VEP was obtained in all eyes. Findings were evaluated in two age strata of 10–29 and 30–49 years. Results Of the 42 eyes in the 10–29 year age group, CS was abnormal in 22 (52%), VEP was also abnormal in 22 (52%), but only 12 eyes (28%) had visual symptoms. Of the 58 eyes in the 30–49 year group, CS was abnormal in 7 (12%), VEP was abnormal in 34 (58%), while only 11 eyes were symptomatic. No single test could detect all of the abnormal eyes. Conclusion The Cambridge Low Contrast Grating test is useful for detection of clinical and subclinical visual dysfunction especially in young patients with multiple sclerosis. Nevertheless, only a combination of CS and VEP tests can detect most cases of visual dysfunction associated with MS. PMID:22737353

  5. Conditions for evoked-potential audiometry in odontocetes

    NASA Astrophysics Data System (ADS)

    Supin, Alexander Ya.

    2005-04-01

    Currently auditory brainstem evoked potentials (ABR) become widely used for audiometry in odontocetes. Depending on the goal, the ABR technique differs with respect of (i) electrode positions, (ii) stimulus parameters, and (iii) threshold evaluation procedure. (I) Optimal electrode positions are vertex (for binaural responses), lateral (for monaural responses), or pharyngeal (for some express investigations). (II) The shorter the stimulus and the wider its spectrum, the more robust the response. Thereafter, narrow-band stimuli provoke low-amplitude ABR with a short dynamic range, but the goal of investigation often requires keeping the stimulus spectrum narrow. Sinusoidally amplitude modulated (SAM) sounds have narrow spectra, thereby provoking low amplitude envelope-following response (EFR); however, EFR can be extracted from noise by Fourier analysis. Modulation rate for SAM sounds must fit a spectrum peak of the ABR waveform. High-frequency sounds are more effective to provoke ABR and EFR than low-frequency ones, so ABR technique is better applicable for measurements in high-frequency ranges. (III) For precise threshold evaluation, low-amplitude responses must be extracted from noise. Apart from the averaging procedure, cross-correlation (for single ABR) or Fourier (for EFR) analysis is helpful to extract and measure low response amplitudes. [Work supported by Russian Basic Research Foundation, Russian President Grant, ONR.

  6. Pattern Visual Evoked Potentials in Dyslexic versus Normal Children

    PubMed Central

    Heravian, Javad; Sobhani-Rad, Davood; Lari, Samaneh; Khoshsima, Mohamadjavad; Azimi, Abbas; Ostadimoghaddam, Hadi; Yekta, Abbasali; Hoseini-Yazdi, Seyed Hosein

    2015-01-01

    Purpose: Presence of neurophysiological abnormalities in dyslexia has been a conflicting issue. This study was performed to evaluate the role of sensory visual deficits in the pathogenesis of dyslexia. Methods: Pattern visual evoked potentials (PVEP) were recorded in 72 children including 36 children with dyslexia and 36 children without dyslexia (controls) who were matched for age, sex and intelligence. Two check sizes of 15 and 60 min of arc were used with temporal frequencies of 1.5 Hz for transient and 6 Hz for steady-state methods. Results: Mean latency and amplitude values for 15 min arc and 60 min arc check sizes using steady state and transient methods showed no significant difference between the two study groups (P values: 0.139/0.481/0.356/0.062). Furthermore, no significant difference was observed between two methods of PVEPs in dyslexic and normal children using 60 min arc with high contrast (P values: 0.116, 0.402, 0.343 and 0.106). Conclusion: The sensitivity of PVEP has high validity to detect visual deficits in children with dyslexic problem. However, no significant difference was found between dyslexia and normal children using high contrast stimuli. PMID:26730313

  7. Calibration assessment in quantitative electroencephalographic brainmapping and evoked potential studies.

    PubMed

    Richards, A K; Hamilton-Bruce, M A

    1994-09-01

    Acquisition of a Cadwell Spectrum 32 resulted in the introduction of quantitative electrophysiological brainmapping techniques in our neurophysiology laboratory. To ascertain the accuracy and consistency of our equipment, we performed the following tests: inputting a calibration signal and measuring the resultant amplitudes for quantitative electroencephalographs (qEEGs) and evoked potentials (EPs) in the mapping and standard montages, inputting a synchronous calibration signal and mapping it at varying times for qEEGs and EPs, as well as re-analysing the same electroencephalographic (EEG) epochs previously selected from 20 control subjects. QEEG amplitudes varied from -5.4% to +5.8% and EPs by 9.5% or less, and after an EP software upgrade, by 5.5% or less. QEEG voltage mapping showed variation of only one color increment across the map, which could, in our example, represent up to 25.2% of the scale used. Re-analysis of previously selected epochs yielded identical results. We have established some of the accuracy and consistency limits of the hard- and software of our system with respect to the quantitative and topographic data. We conclude that such systems need to be calibration-checked in the laboratories in which they are used, with an independent signal generator. Users also need to be aware that scaling of topographic maps could lead to erroneous conclusions, as perceived amplitude changes could affect the interpretation of both initial and serial studies. PMID:7980205

  8. Long-latency evoked potentials to irrelevant, deviant stimuli

    NASA Technical Reports Server (NTRS)

    Snyder, E.; Hillyard, S. A.

    1976-01-01

    Occasional shifts of loudness in a repetitive train of clicks elicited a late-positive wave (P3a) in nonattending subjects which peaked at a mean latency of 258 msec and had a frontocentral scalp distribution; P3a was typically preceded by an 'N2' component at 196 msec. The P3a wave was distinguishable from the longer-latency (378 msec) parietocentrally distributed 'P3b' wave that was evoked by the same stimulus in an actively attending subject, thus confirming the findings of Squires et al. (1975). Infrequently presented single sounds did not produce large or consistent N2-P3a components; the critical condition for the generation of an N2-P3a wave seemed to be that the infrequent sounds represent a deviation (intensity increment or decrement) from a repetitive background. Furthermore, increasing the repetition rate of the background clicks drastically reduced N1-P2 amplitude but had little effect on the amplitude of N2-P3a. This suggests that N2-P3a is not simply a delayed N1-P2 'vertex potential', but rather reflects the operation of a 'mismatch' detector, which registers deviations from an ongoing auditory background.

  9. ACUTE SULFOLANE EXPOSURE PRODUCES TEMPERATURE-INDEPENDENT AND DEPENDENT CHANGES IN VISUAL EVOKED POTENTIALS

    EPA Science Inventory

    The report describes the consequences of acute exposure to sulfolane upon the visual system, as measured using flash evoked potential (FEPs) and pattern reversal evoked potentials (PREPs). A single injection of either 1/2 or 1/4, but not 1/8 the i.p. LD50 (1600 mg/kg) produced si...

  10. Magnetic motor evoked potentials (MEP) in diseases of the spinal cord.

    PubMed

    Linden, D; Berlit, P

    1994-11-01

    Transcranial magnetic stimulation (TMS) is a non-invasive diagnostic method particularly suited to investigation of the long motor tracts. The clinical value of this method in many cortical and subcortical diseases has been well established, but comparable studies for most spinal cord diseases have still to be made. Forty patients in whom spinal cord disease was established by clinical examination, cerebrospinal fluid examination, and magnetic resonance imaging (MRI) were studied by means of somatosensory evoked potentials (SEP, median and tibial nerve stimulation) and magnetic motor evoked potentials (MEP, first dorsal interosseus and tibialis anterior muscle recordings after transcranial and spinal stimulation). The underlying pathology was neoplastic (n = 16), inflammatory (n = 15) or ischemic (n = 9). Clinical signs and symptoms ranged from slight sensory disturbances to complete paraplegia and had developed within minutes (ischemia) or over many years (benign neoplastic disease). The overall frequency of pathological SEP was slightly higher than that of MEP (78% vs 68%) which was statistically not significant (p > 0.05). This was also true for the subgroups, except for pure motor disorders, which gave the same yield for both methods. Decreased amplitudes or absence of MEP were more frequent in neoplastic than in inflammatory lesions (75% vs 33%, p < 0.05). In the latter, however, MEP more often occurred with increased latencies (40% vs 31%, p > 0.05, n.s.). Pathological SEP were found in 75% of patients presenting with pure motor abnormalities, while pathological MEP were found in 30% of patients with pure sensory disturbances.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7887135

  11. Theta Burst Stimulation of the Cerebellum Modifies the TMS-Evoked N100 Potential, a Marker of GABA Inhibition

    PubMed Central

    2015-01-01

    Theta burst stimulation (TBS) of the cerebellum, a potential therapy for neurological disease, can modulate corticospinal excitability via the dentato-thalamo-cortical pathway, but it is uncertain whether its effects are mediated via inhibitory or facilitatory networks. The aim of this study was to investigate the effects of 30Hz cerebellar TBS on the N100 waveform of the TMS-evoked potential (TEP), a marker of intracortical GABAB-mediated inhibition. 16 healthy participants (aged 18–30 years; 13 right handed and 3 left handed) received 30Hz intermittent TBS (iTBS), continuous TBS (cTBS) or sham stimulation over the right cerebellum, in three separate sessions. The first 8 participants received TBS at a stimulus intensity of 80% of active motor threshold (AMT), while the remainder received 90% of AMT. Motor evoked potentials (MEP) and TEP were recorded before and after each treatment, by stimulating the first dorsal interosseus area of the left motor cortex. Analysis of the 13 right handed participants showed that iTBS at 90% of AMT increased the N100 amplitude compared to sham and cTBS, without significantly altering MEP amplitude. cTBS at 80% of active motor threshold decreased the N100 amplitude and cTBS overall reduced resting MEP amplitude. The study demonstrates effects of 30Hz cerebellar TBS on inhibitory cortical networks that may be useful for treatment of neurological conditions associated with dysfunctional intracortical inhibition. PMID:26529225

  12. Dipole source analyses of laser evoked potentials obtained from subdural grid recordings from primary somatic sensory cortex.

    PubMed

    Baumgärtner, Ulf; Vogel, Hagen; Ohara, Shinji; Treede, Rolf-Detlef; Lenz, Fred

    2011-08-01

    The cortical potentials evoked by cutaneous application of a laser stimulus (laser evoked potentials, LEP) often include potentials in the primary somatic sensory cortex (S1), which may be located within the subdivisions of S1 including Brodmann areas 3A, 3B, 1, and 2. The precise location of the LEP generator may clarify the pattern of activation of human S1 by painful stimuli. We now test the hypothesis that the generators of the LEP are located in human Brodmann area 1 or 3A within S1. Local field potential (LFP) source analysis of the LEP was obtained from subdural grids over sensorimotor cortex in two patients undergoing epilepsy surgery. The relationship of LEP dipoles was compared with dipoles for somatic sensory potentials evoked by median nerve stimulation (SEP) and recorded in area 3B (see Baumgärtner U, Vogel H, Ohara S, Treede RD, Lenz FA. J Neurophysiol 104: 3029-3041, 2010). Both patients had an early radial dipole in S1. The LEP dipole was located medial, anterior, and deep to the SEP dipole, which suggests a nociceptive dipole in area 3A. One patient had a later tangential dipole with positivity posterior, which is opposite to the orientation of the SEP dipole in area 3B. The reversal of orientations between modalities is consistent with the cortical surface negative orientation resulting from superficial termination of thalamocortical neurons that receive inputs from the spinothalamic tract. Therefore, the present results suggest that the LEP may result in a radial dipole consistent with a generator in area 3A and a putative later tangential generator in area 3B. PMID:21593389

  13. Felt and seen pain evoke the same local patterns of cortical activity in insular and cingulate cortex.

    PubMed

    Corradi-Dell'Acqua, Corrado; Hofstetter, Christoph; Vuilleumier, Patrik

    2011-12-01

    The discovery of regions in the human brain (e.g., insula and cingulate cortex) that activate both under direct exposure to pain and when perceiving pain in others has been interpreted as a neural signature of empathy. However, this overlap raises the question of whether it may reflect a unique distributed population of bimodal neurons or, alternatively, the activity of intermingled but independent populations. We used fMRI on 28 female volunteers and used multivariate pattern analysis techniques to probe for more fine-grain spatial representations of seen and felt pain. Using a whole-brain approach, we found that only in the anterior insula (bilaterally) the distribution of cortical activity evoked by seeing another person's hand in pain was spatially similar to that of pain felt on one's own hand. Subsequent region of interest analyses also implicated the middle insula (right hemisphere) and the middle cingulate cortex. Furthermore, for the anterior insula, the spatial distribution of activity associated with one's pain also replicates that of the perception of negative but painless stimuli. Our data show how the neural representations of aversive events affecting oneself are also recruited when the same events affect others, and provide the stronger evidence thus far of a unique distributed cortical ensemble coding for aversive events regardless of the subject who is affected. PMID:22159113

  14. The Use of Evoked Potentials in Sleep Research

    PubMed Central

    Colrain, Ian M.; Campbell, Kenneth B.

    2009-01-01

    Averaged event-related potentials (ERPs) represent sensory and cognitive processing of stimuli during wakefulness independent of behavioural responses, and reflect the underlying state of the CNS during sleep. Components measured during wakefulness which are reflective of arousal state or the automatic switching of attention are sensitive to prior sleep disruption. Components reflecting active attentional influences during the waking state appear to be preserved in a rudimentary form during REM sleep, but in a way that highlights the differences in the neurochemical environment between wakefulness and REM sleep. Certain ERP components only appear within sleep. These begin to emerge at NREM sleep onset and may reflect inhibition of information processing and thus have utility as markers of the functional status of sleep preparatory mechanisms. These large amplitude NREM components represent synchronized burst firing of large number of cortical cells and are a reflection of the nervous system’s capacity to generate delta frequency EEG activity. As such they are useful in assessing the overall integrity of the nervous system in populations not showing substantial amounts of SWS as measured using traditional criteria. While requiring care in their interpretation, ERPs nonetheless provide a rich tool to investigators interested in probing the nervous system to evaluate daytime functioning in the face of sleep disruption, the ability of the sleeping nervous system to monitor the external environment, and the ability of the nervous system to respond to stimuli in a manner consistent with the initiation or maintenance of sleep. PMID:17628317

  15. Laser flash effects on laser speckle shift visual evoked potential.

    PubMed

    Schmeisser, E T

    1985-10-01

    Steady-state visual evoked potentials (VEP's) were recorded from four cynomolgus monkeys in response to a sinusoidally oscillating 10 degrees helium-neon laser speckle field (632.8 nm), moving vertically 2.5 degrees at 8 shifts per second. A 5-pulse flash train at the maximum permissible exposure (MPE) dose from a collimated Q-switched frequency-doubled neodymium laser (532 nm) was superimposed on the foveal stimulus and the subsequent disruption and recovery of the VEP measured. Minimal disruption of the response signal magnitude was demonstrated (0.1 greater than p greater than 0.05) which recovered within 300 ms of the termination of the pulse train. A small but significant (p less than 0.01) disruption of phase entrainment was also noted that recovered within the same period. This is contrasted with a second experiment with three monkeys in which an argon (514 nm) laser served both as the speckle stimulus source and as the shuttered flash. Exposure to collimated MPE argon radiation for 250 ms immediately depressed the VEP (97%, p less than 0.01) and showed recovery to 70% of the pre-flash baseline only after 3 s. Phase lock was also severely degraded for several seconds. These results imply that visual processing of nonacuity-limited medium contrast stimuli with broad spatial frequency content will probably not be materially affected by ultra-short pulsed laser exposure at these energy levels and frequencies. However, even safe levels of collimated continuous laser light may have severe effects on vision that could parallel flash effects seen with Xenon discharge flash lamps. PMID:4073205

  16. Magnetic motor evoked potentials during methohexital anesthesia in the dog.

    PubMed

    Young SS; discussion 495; Boermans, H J; Sylvestre, A M

    1994-03-01

    Magnetic motor evoked potentials (MMEPs) were recorded from the right cranial tibial muscle after magnetic stimulation of the left motor cortex in six dogs sedated with oxymorphone. Anesthesia was induced with an intravenous bolus of 5.5 mg/kg of methohexital and maintained with a methohexital infusion. The dogs inspired 100% oxygen during anesthesia. Blood pressure, heart rate, respiratory rate, esophageal temperature, and end-tidal carbon dioxide tension were recorded. The depth of anesthesia was increased until the amplitude of the MMEP was less than 5% of the control value, and the dogs were then allowed to recover. Every 5 minutes during anesthesia, a blood sample was taken for methohexital assay and at the same time, four replicate MMEPs were recorded. Plasma methohexital levels were significantly (P < 0.05) correlated with heart rate (p = 0.38) and end-tidal carbon dioxide tension (p = 0.49) and negatively correlated with respiratory rate (p = 0.74). There was no significant correlation between blood pressure and methohexital levels. The dogs regained consciousness at a plasma methohexital level of 10.4 +/- 3.8 micrograms/ml (mean +/- SD). The amplitude of the MMEP decreased significantly with increasing methohexital levels. In four dogs, the relationship was reasonably linear. The MMEP disappeared at a plasma methohexital level of 23 +/- 6.6 micrograms/ml. The latency of onset of the MMEP increased significantly from its control value of 14.7 +/- 1.0 ms to 17.5 +/- 1.3 ms at the highest methohexital levels at which MMEPs were recordable. This study demonstrated that MMEPs can be reliably recorded under methohexital anesthesia. PMID:8190225

  17. Measurement of evoked potentials during thalamic deep brain stimulation

    PubMed Central

    Kent, Alexander R.; Swan, Brandon D.; Brocker, David T.; Turner, Dennis A.; Gross, Robert E.; Grill, Warren M.

    2014-01-01

    Background Deep brain stimulation (DBS) treats the symptoms of several movement disorders, but optimal selection of stimulation parameters remains a challenge. The evoked compound action potential (ECAP) reflects synchronized neural activation near the DBS lead, and may be useful for feedback control and automatic adjustment of stimulation parameters in closed-loop DBS systems. Objectives Determine the feasibility of recording ECAPs in the clinical setting, understand the neural origin of the ECAP and sources of any stimulus artifact, and correlate ECAP characteristics with motor symptoms. Methods The ECAP and tremor response were measured simultaneously during intraoperative studies of thalamic DBS, conducted in patients who were either undergoing surgery for initial lead implantation or replacement of their internal pulse generator. Results There was large subject-to-subject variation in stimulus artifact amplitude, which model-based analysis suggested may have been caused by glial encapsulation of the lead, resulting in imbalances in the tissue impedance between the contacts. ECAP recordings obtained from both acute and chronically implanted electrodes revealed that specific phase characteristics of the signal varied systematically with stimulation parameters. Further, a trend was observed in some patients between the energy of the initial negative and positive ECAP phases, as well as secondary phases, and changes in tremor from baseline. A computational model of thalamic DBS indicated that direct cerebellothalamic fiber activation dominated the clinically measured ECAP, suggesting that excitation of these fibers is critical in DBS therapy. Conclusions This work demonstrated that ECAPs can be recorded in the clinical setting and may provide a surrogate feedback control signal for automatic adjustment of stimulation parameters to reduce tremor amplitude. PMID:25457213

  18. Vestibular Evoked Myogenic Potentials in a Female Population with Migraine.

    PubMed

    Yetiser, Sertac; Gok, Meltem Hale; Kutukcu, Yasar; Ince, Dilay

    2016-06-01

    The objective is to analyze the vestibular system by vestibular evoked myogenic potential (VEMP) in 30 female patients with migraine and balance problem in a controlled study. Thirty female patients with migraine and vestibular problems were enrolled in the study (2009-2012). Fifteen age-matched healthy subjects were selected as the controls. Air conduction cervical VEMP was used. Tone-burst sound stimuli of 95 dB nHL with rarefaction polarity, 5 Hz stimulus repetition rate, 1 ms rise/fall time and 2 ms plateau time were delivered at 500 Hz. 200 sweeps were averaged. Myogenic responses were amplified and band-pass filtered (800-10 Hz). The latency and the amplitude of p1 and n1 waves and interpeak amplitude and latency differences were measured. Results were given as mean and SDs. Interaural p1 and n1 amplitude greater than 30 % asymmetry was accepted as abnormal. VEMP results were compared with controls. The One-way ANOVA test was used. Statistical significance was set at P < 0.05. VEMP responses were elicited in all controls and the patients. Comparative analysis of p1 amplitude between the patients and the controls was statistically significant (P = 0.010). P1n1 interaural amplitude difference was greater than 30 % in 4 patients (13.4 %). No statistically significant difference was found when comparing latency of all wave forms between the patients and healthy controls (P > 0.05). VEMP is an useful tool to test the vestibular system in patients with migraine and balance problem at the very early period. Clinicians should always consider migraine in patients with vertigo. PMID:27340638

  19. Diagnostic accuracy of somatosensory evoked potential monitoring during scoliosis fusion.

    PubMed

    Thirumala, Parthasarathy D; Cheng, Hannah L; Loke, Yoon K; Kojo Hamilton, D; Balzer, Jeffrey; Crammond, Donald J

    2016-08-01

    The goal of this review was to ascertain the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) changes to predict perioperative neurological outcome in patients undergoing spinal deformity surgery to correct adolescent idiopathic scoliosis (AIS). The authors searched PubMed/MEDLINE and World Science databases to retrieve reports and/or experiments from January 1950 through January 2014 for studies on SSEP use during AIS surgery. All motor and sensory deficits were noted in the neurological examination administered after the procedure which was used to determine the effectiveness of SSEP as an intraoperative monitoring technique. Fifteen studies identified a total of 4763 procedures on idiopathic patients. The observed incidence of neurological deficits was 1.11% (53/4763) of the sample population. Of the patients with new postoperative neurological deficits 75.5% (40/53) showed significant SSEP changes, and 24.5% (13/53) did not show significant change. Pooled analysis using the bivariate model showed SSEP change with pooled sensitivity (average 84%, 95% confidence interval 59-95%) and specificity (average 98%, 95% confidence interval 97-99%). The diagnostic odds ratio of a patient who had a new neurological deficit with SSEP changes was a diagnostic odds ratio of 340 (95% confidence interval 125-926). Overall, detection of SSEP changes had excellent discriminant ability with an area under the curve of 0.99. Our meta-analysis covering 4763 operations on idiopathic patients showed that it is a highly sensitive and specific test and that iatrogenic spinal cord injury resulting in new neurological deficits was 340 times more likely to have changes in SSEP compared to those without any new deficits. PMID:27021224

  20. Evoked potential changes in clinically definite multiple sclerosis: a two year follow up study.

    PubMed Central

    Walsh, J C; Garrick, R; Cameron, J; McLeod, J G

    1982-01-01

    Visual, spinal and somatosensory evoked potentials were performed on 56 patients with clinically definite multiple sclerosis at the beginning and end of a 2 1/2 year follow-up period. At the initial examination one or both visual evoked potentials were abnormal in all but nine patients (84%), five of whom had abnormalities of either spinal or somatosensory evoked responses; that is, one or more abnormal results were obtained from 52 of 56 (91%) patients. At the final examination there were abnormalities of one or more evoked potentials in 55 of the 56 (98%) patients. There was an increase in latency of the components of the evoked responses over the period; reduction in latency in individual patients was exceptional. The change in these electrophysiological measurements correlated with the increase in clinical disability of the group of patients over the period of study. PMID:7119812

  1. Synaptic potentials evoked by convergent somatosensory and corticocortical inputs in raccoon somatosensory cortex: substrates for plasticity.

    PubMed

    Smits, E; Gordon, D C; Witte, S; Rasmusson, D D; Zarzecki, P

    1991-09-01

    1. "Unmasking" of weak synaptic connections has been suggested as a mechanism for the early changes in cortical topographic maps that follow alterations of sensory activity. For such a mechanism to operate, convergent sensory inputs must already exist in the normal cortex. 2. We tested for topographic and cross-modality convergence in primary somatosensory cortex of raccoon. The representation of glabrous skin of forepaw digits was chosen because, even though it is dominated by inputs from the glabrous skin of a single digit, it nevertheless comes to respond to stimulation of other digits when, e.g., a digit is removed. 3. Intracellular recordings were made from 109 neurons in the representation of glabrous skin of digit 4. Neurons were tested for somatosensory inputs with electrical and natural stimulation of digits. 4. Excitatory postsynaptic potentials (EPSPs) were evoked in 100% of the neurons (109/109) by electrical stimulation of glabrous skin of digit 4, and in 79% (31 of 39) by vibrotactile stimulation. 5. Glabrous skin of digit 4 was not the sole source of somatosensory inputs. A minority of neurons generated EPSPs after electrical stimulation of hairy skin of digit 4 (10 of 98 neurons, 10%). Electrical stimulation of digits 3 or 5 evoked EPSPs in 22 of 103 neurons (21%). Natural stimulation (vibrotactile or hair bending) was also effective in most of these latter cases (digit 3, 6/7; digit 5, 9/10). 6. Intracortical microstimulation of the "heterogeneous zone" was used to test for corticocortical connections to neurons in the glabrous zone.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1753280

  2. Diagnostic value of Hoover sign and motor-evoked potentials in acute somatoform unilateral weakness and sensory impairment mimicking vascular stroke.

    PubMed

    Shahar, Eli; Ravid, Sarit; Hafner, Hava; Chistyakov, Andrei; Shcif, Aharon

    2012-07-01

    Acute unilateral weakness along with sensory impairment is commonly caused by obstruction of major cortical arteries in either adults or children. A somatoform presentation mimicking acute vascular stroke is very rare, especially in the pediatric age group. Here we report three adolescents presenting with acute unilateral weakness and sensory impairment along with diminished tendon reflexes who were suspected to have an acute stroke but who had developed a somatoform psychogenic disorder. Two adolescents had complete hemiplegia and one had weakness of the left leg - two had moved the alleged paralytic limbs during sleep. A normal Hoover sign was suggestive of a somatoform psychogenic etiology rather than true vascular stroke. Cortical and spinal MRI, motor-evoked potentials (MEP) and somatosensory-evoked potentials were normal. All adolescents recovered completely. Therefore, a somatoform conversion reaction should be considered in children presenting with acute unilateral weakness and sensory alterations, which is corroborated by a normal Hoover sign and intact MEP. PMID:22537658

  3. Neurophysiological Effects of Meditation Based on Evoked and Event Related Potential Recordings

    PubMed Central

    Singh, Nilkamal; Telles, Shirley

    2015-01-01

    Evoked potentials (EPs) are a relatively noninvasive method to assess the integrity of sensory pathways. As the neural generators for most of the components are relatively well worked out, EPs have been used to understand the changes occurring during meditation. Event-related potentials (ERPs) yield useful information about the response to tasks, usually assessing attention. A brief review of the literature yielded eleven studies on EPs and seventeen on ERPs from 1978 to 2014. The EP studies covered short, mid, and long latency EPs, using both auditory and visual modalities. ERP studies reported the effects of meditation on tasks such as the auditory oddball paradigm, the attentional blink task, mismatched negativity, and affective picture viewing among others. Both EP and ERPs were recorded in several meditations detailed in the review. Maximum changes occurred in mid latency (auditory) EPs suggesting that maximum changes occur in the corresponding neural generators in the thalamus, thalamic radiations, and primary auditory cortical areas. ERP studies showed meditation can increase attention and enhance efficiency of brain resource allocation with greater emotional control. PMID:26137479

  4. 3D graphics, virtual reality, and motion-onset visual evoked potentials in neurogaming.

    PubMed

    Beveridge, R; Wilson, S; Coyle, D

    2016-01-01

    A brain-computer interface (BCI) offers movement-free control of a computer application and is achieved by reading and translating the cortical activity of the brain into semantic control signals. Motion-onset visual evoked potentials (mVEP) are neural potentials employed in BCIs and occur when motion-related stimuli are attended visually. mVEP dynamics are correlated with the position and timing of the moving stimuli. To investigate the feasibility of utilizing the mVEP paradigm with video games of various graphical complexities including those of commercial quality, we conducted three studies over four separate sessions comparing the performance of classifying five mVEP responses with variations in graphical complexity and style, in-game distractions, and display parameters surrounding mVEP stimuli. To investigate the feasibility of utilizing contemporary presentation modalities in neurogaming, one of the studies compared mVEP classification performance when stimuli were presented using the oculus rift virtual reality headset. Results from 31 independent subjects were analyzed offline. The results show classification performances ranging up to 90% with variations in conditions in graphical complexity having limited effect on mVEP performance; thus, demonstrating the feasibility of using the mVEP paradigm within BCI-based neurogaming. PMID:27590974

  5. Auditory evoked potentials in a bottlenose dolphin during moderate-range echolocation tasks.

    PubMed

    Finneran, James J; Mulsow, Jason; Houser, Dorian S

    2013-12-01

    Studies with echolocating odontocetes have suggested that forms of automatic gain control mediate auditory electrophysiological responses to target-related echoes. This study used a phantom echo generator and auditory evoked potential measurements to examine automatic gain control in a bottlenose dolphin. Auditory evoked potentials to outgoing clicks and incoming echoes were recorded for simulated ranges from 2.5 to 80 m. When geometric spreading loss was simulated, echo-evoked potential amplitudes were essentially constant up to 14 m and progressively decreased with increasing range. When the echo levels were held constant relative to clicks, echo-evoked potential amplitudes increased with increasing range up to 80 m. These results suggest that automatic gain control maintains distance-independent echo-evoked potential amplitudes at close range, but does not fully compensate for attenuation due to spreading loss at longer ranges. The automatic gain control process appears to arise from an interaction of transmitter and receiver based processes, resulting in a short-range region of distance-independent echo-evoked potential amplitudes for relevant targets, and a longer-range region in which echo-evoked potential amplitudes are reduced. PMID:25669263

  6. Prandial States Modify the Reactivity of the Gustatory Cortex Using Gustatory Evoked Potentials in Humans

    PubMed Central

    Jacquin-Piques, Agnès; Gaudillat, Stéphanie; Mouillot, Thomas; Gigot, Vincent; Meillon, Sophie; Leloup, Corinne; Penicaud, Luc; Brondel, Laurent

    2016-01-01

    Previous functional Magnetic Resonance Imaging studies evaluated the role of satiety on cortical taste area activity and highlighted decreased activation in the orbito-frontal cortex when food was eaten until satiation. The modulation of orbito-frontal neurons (secondary taste area) by ad libitum food intake has been associated with the pleasantness of the food's flavor. The insula and frontal operculum (primary taste area) are also involved in reward processing. The aim was to compare human gustatory evoked potentials (GEP) recorded in the primary and secondary gustatory cortices in a fasted state with those after food intake. Fifteen healthy volunteers were enrolled in this observational study. In each of two sessions, two GEP recordings were performed (at 11:00 am and 1:30 pm) in response to sucrose gustatory stimulation, and a sucrose-gustatory threshold was determined. During one session, a standard lunch was provided between the two GEP recordings. During the other session, subjects had nothing to eat. Hunger sensation, wanting, liking, and the perception of the solution's intensity were evaluated with visual analog scales. GEP latencies measured in the Pz (p < 0.001), Cz (p < 0.01), Fz (p < 0.001) recordings (primary taste area) were longer after lunch than in the pre-prandial condition. Fp1 and Fp2 latencies (secondary taste area) tended to be longer after lunch, but the difference was not significant. No difference was observed for the sucrose-gustatory threshold regardless of the session and time. Modifications in the primary taste area activity during the post-prandial period occurred regardless of the nature of the food eaten and could represent the activity of the frontal operculum and insula, which was recently shown to be modulated by gut signals (GLP-1, CCK, ghrelin, or insulin) through vagal afferent neurons or metabolic changes of the internal milieu after nutrient absorption. This trial was registered at clinicalstrials.gov as NCT02472444. PMID

  7. Cortical Metabotropic Glutamate Receptors Contribute to Habituation of a Simple Odor-Evoked Behavior

    PubMed Central

    Best, Aaron R.; Thompson, Jason V.; Fletcher, Max L.; Wilson, Donald A.

    2008-01-01

    Defining the circuits that are involved in production and cessation of specific behaviors is an ultimate goal of neuroscience. Short-term behavioral habituation is the response decrement observed in many behaviors that occurs during repeated presentation of non-reinforced stimuli. Within a number of invertebrate models of short-term behavioral habituation, depression of a defined synapse has been implicated as the mechanism. However, the synaptic mechanisms of short-term behavioral habituation have not been identified within mammals. We have shown previously that a presynaptic metabotropic glutamate receptor (mGluR)-dependent depression of synapses formed by olfactory bulb afferents to the piriform (olfactory) cortex significantly contributes to adaptation of cortical odor responses. Here we show that blockade of mGluRs within the olfactory cortex of awake, behaving rats diminishes habituation of a simple odor-induced behavior, strongly implicating a central mechanism for sensory gating in olfaction. PMID:15758159

  8. Characterization of electrically evoked field potentials in the medial prefrontal cortex and orbitofrontal cortex of the rat: modulation by monoamines

    PubMed Central

    Wallace, Joanne; Jackson, Rosanna K; Shotton, Tanya L; Munjal, Ishaana; McQuade, Richard; Gartside, Sarah E

    2015-01-01

    Medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) play critical roles in cognition and behavioural control. Glutamatergic, GABAergic, and monoaminergic dysfunction in the prefrontal cortex has been hypothesised to underlie symptoms in neuropsychiatric disorders. Here we characterised electrically-evoked field potentials in the mPFC and OFC. Electrical stimulation evoked field potentials in layer V/VI of the mPFC and layer V of the OFC. The earliest component (approximately 2 ms latency) was insensitive to glutamate receptor blockade and was presumed to be presynaptic. Later components were blocked by 6,7-dinitroquinoxaline-2,3-dione (DNQX (20 μM) and were assumed to reflect monosynaptic (latency 4-6 ms) and polysynaptic activity (latency 6-40 ms) mediated by glutamate via AMPA/kainate receptor. In the mPFC, but not the OFC, the monosynaptic component was also partly blocked by 2-amino-5-phosphonopentanoic acid (AP-5 (50-100 μM) indicating the involvement of NMDA receptors. Bicuculline (3-10 μM) enhanced the monosynaptic component suggesting electrically-evoked and/or glutamate induced GABA release inhibits the monosynaptic component via GABAA receptor activation. There were complex effects of bicuculline on polysynaptic components. In the mPFC both the mono- and polysynaptic components were attenuated by 5-HT (10-100 μM) and NA (30 and 60 μM) and the monosynaptic component was attenuated by DA (100 μM). In the OFC the mono-and polysynaptic components were also attenuated by 5-HT (100 μM), NA (10-100 μM) but DA (10-100 μM) had no effect. We propose that these pharmacologically characterised electrically-evoked field potentials in the mPFC and OFC are useful models for the study of prefrontal cortical physiology and pathophysiology. PMID:23932190

  9. Monoaminergic substrates underlying cocaine-induced enhancement of somatosensory-evoked discharges in rat barrel field cortical neurons.

    PubMed

    Waterhouse, B D; Gould, E M; Bekavac, I

    1996-11-01

    Previously, we have described a selective potentiating effect of systemically administered cocaine (0.25-1.0 mg/kg i.v.) on long-latency excitatory responses (E2) of rat "barrel field" cortical neurons to mystacial vibrissae stimulation. The rat trigeminal system receives both norepinephrine (NE) and serotonin (5-HT)-containing afferents, but only minimal input from dopaminergic sources. The goal of the present study was to determine which of these monoamine systems was responsible for the previously observed facilitating action of cocaine on E2 responses of barrel field cortical neurons. Two approaches were used: 1) evaluation of cocaine effects on cortical neuron responses to whisker stimulation in NE- or 5-HT-depleted animals and 2) assessment of the effects of selective monoamine uptake blockers on cortical neuron responses to whisker deflection. Extracellular recordings were obtained from spontaneously active neurons in the barrel field cortex of halothane-anesthetized rats. Spontaneous activity and cellular responses to mechanical displacement of a single whisker were monitored before and after systemic (i.v.) administration of either cocaine or one of the following selective uptake blockers, fluoxetine (5-HT), desipramine (NE) and GBR12909 (dopamine). Cocaine-induced increases in the E2 response were observed in N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4, noradrenergic neurotoxin)-treated animals, but were reduced or abolished in p-chlorophenylalanine-treated (5-HT depletion) rats. Fluoxetine and desipramine, but not GBR12909, produced cocaine-like potentiation of the E2 response to whisker stimulation. These results point to a 5-HT-dependent mechanism as the substrate underlying cocaine's facilitating effects on long-latency somatosensory cortical neuron responses to receptive field stimulation. PMID:8930160

  10. Ocular Vestibular Evoked Myogenic Potentials Using Head Striker Stimulation

    NASA Technical Reports Server (NTRS)

    De Dios, Y. E.; Gadd, N. E.; Kofman, I. S.; Peters, B. T.; Reschke, M.; Bloomberg, J. J.; Wood, S. J.; Noohibezanjani, F.; Kinnaird, C.; Seidler, R. D.; Mulavara, A. P.

    2016-01-01

    Introduction: Over the last two decades, several studies have been published on the impact of long-duration (i.e., 22 days or longer) spaceflight on the central nervous system (CNS). In consideration of the health and performance of crewmembers in flight and post-flight, we are conducting a controlled prospective longitudinal study to investigate the effects of spaceflight on the extent, longevity and neural bases of sensorimotor, cognitive, and neural changes. Multiple studies have demonstrated the effects of spaceflight on the vestibular system. One of the supporting tests conducted in this protocol is the Vestibular Evoked Myogenic Potential (VEMP) test that provides a unilateral measure of otolith (saccule and utricle) function. A different approach was taken for ocular VEMP (oVEMP) testing using a head striker system (Wackym et al. 2012). The oVEMP is generally considered to be a measure of utricle function. The the otolithic input to the inferior oblique muscle is predominately from the utricular macula. Thus, quantitatively, oVEMP tests utricular function. Another practical extension of these relationships is that the oVEMP reflects the superior vestibular nerve function. Methods: Ground testing was administered on 16 control subjects and for 8 subjects over four repeated sessions spanning 70 days. The oVEMP was elicitied via a hand held striker by a vibrotactile pulse presented at the rate of 1 Hz for 24 seconds on the side of the head as subjects lay supine on a gurney. Subjects were directed to gaze approximately 25 degrees above straight ahead in semi-darkness. For the oVEMP electromyograms will be recorded with active bipolar electrodes (Delsys Inc., Boston, MA) on the infra-orbital ridge 1 cm below the eyelid with a reference electrode on the below the knee cap. The EMG potentials were amplified; band-pass filtered using a BagnoliTM Desktop EMG System (Delsys Inc., Boston, MA, USA). This EMG signal is sampled at 10 kHz and the data stimulus onset to

  11. A novel model incorporating two variability sources for describing motor evoked potentials

    PubMed Central

    Goetz, Stefan M.; Luber, Bruce; Lisanby, Sarah H.; Peterchev, Angel V.

    2014-01-01

    Objective Motor evoked potentials (MEPs) play a pivotal role in transcranial magnetic stimulation (TMS), e.g., for determining the motor threshold and probing cortical excitability. Sampled across the range of stimulation strengths, MEPs outline an input–output (IO) curve, which is often used to characterize the corticospinal tract. More detailed understanding of the signal generation and variability of MEPs would provide insight into the underlying physiology and aid correct statistical treatment of MEP data. Methods A novel regression model is tested using measured IO data of twelve subjects. The model splits MEP variability into two independent contributions, acting on both sides of a strong sigmoidal nonlinearity that represents neural recruitment. Traditional sigmoidal regression with a single variability source after the nonlinearity is used for comparison. Results The distribution of MEP amplitudes varied across different stimulation strengths, violating statistical assumptions in traditional regression models. In contrast to the conventional regression model, the dual variability source model better described the IO characteristics including phenomena such as changing distribution spread and skewness along the IO curve. Conclusions MEP variability is best described by two sources that most likely separate variability in the initial excitation process from effects occurring later on. The new model enables more accurate and sensitive estimation of the IO curve characteristics, enhancing its power as a detection tool, and may apply to other brain stimulation modalities. Furthermore, it extracts new information from the IO data concerning the neural variability—information that has previously been treated as noise. PMID:24794287

  12. Facilitatory effect of thinking about movement on magnetic motor-evoked potentials.

    PubMed

    Kiers, L; Fernando, B; Tomkins, D

    1997-08-01

    To investigate the facilitatory effect of thinking about movement on motor evoked potential (MEP) amplitude, we recorded MEPs in two test muscles during rest, with the subject thinking about contracting the test muscle but without subsequent contraction, and during 10% maximum voluntary contraction. Stimuli were delivered at 10% above resting motor threshold and at 90-100% stimulator output. H-reflexes, recorded in flexor carpi radialis, were obtained during rest and think conditions. MEP threshold was lower during the think condition (P = 0.004). At both stimulus intensities, median MEP amplitudes and areas were significantly (P < 0.001) larger during the think paradigm compared with rest. This effect was greater at the lower stimulus intensity. There was no significant difference in latency (P = 0.15). In 4/8 subjects, H-reflex amplitudes were mildly facilitated (P < 0.05) during the think condition. We conclude that thinking about movement without detectable EMG activity has a facilitatory effect on magnetic MEPs. The absence of a MEP latency shift between rest and think conditions and absence of a consistent increase in H-reflex amplitude suggests this effect occurs largely at the cortical level. In some subjects, however, an increase in spinal motoneuron excitability may also contribute. PMID:9284233

  13. Neural generators of the auditory evoked potential components P3a and P3b.

    PubMed

    Wronka, Eligiusz; Kaiser, Jan; Coenen, Anton M L

    2012-01-01

    The aim of the present study was to define the scalp topography of the two subcomponents of the P3 component of the auditory evoked potential elicited in a three-stimulus oddball paradigm and to identify their cortical generators using the standardized low resolution electromagnetic tomography (sLORETA). Subjects were presented with a random sequence of auditory stimuli and instructed to respond to an infrequently occurring target stimulus inserted into a sequence of frequent standard and rare non-target stimuli. Results show that the magnitude of the frontal P3a is determined by the relative physical difference among stimuli, as it was larger for the stimulus more deviant from the standard. Major neural generators of the P3a were localized within frontal cortex and anterior cingulate gyrus. In contrast to this, the P3b, showing maximal amplitude at parietal locations, was larger for stimuli demanding a response than for the rare non-target. Major sources of the P3b included the superior parietal lobule and the posterior part of the cingulate gyrus. Our findings are in line with the hypothesis that P3a is related to alerting activity during the initial allocation of attention, while P3b is related to activation of a posterior network when the neuronal model of perceived stimulation is compared with the attentional trace. PMID:22508084

  14. Dynamic topography of visual evoked potentials and extrageniculate projection in case of Riddoch phenomenon.

    PubMed

    Tsutsui, J; Ichihashi, K; Kimura, H

    1984-01-01

    A 34-year-old woman showing the Riddoch phenomenon was studied by the technique of dynamic topography of visual evoked potential (VEP). This case had cortical blindness which developed during the process of massive intestinal hemorrhage, shock and surgery. The visual acuity was limited to hand movement, and perception of white and colored light was present, but there was no form recognition. Tracking eye movement for a flashlight was possible and optokinetic nystagmus (OKN) also appeared. CT-scan showed a diffuse low density area in the white matter of the occipital lobe. The VEPs by flash and a checkerboard of 60'-100' were detectable. Dynamic topography of the VEP showed that a strong negative deflection from the brainstem appeared at around 30 msec and this deflection expanded to the parietal region at about 90 msec. Subsequently, a positive deflection extending from the frontal region to the occipital region continued at 100 msec to 150 msec. Such a process of reaction is not observed in the normal subject. These findings suggest that the visual reaction was conducted abnormally through the extrageniculate system; from the brainstem to the parietal area and then to the occipital area. PMID:6748358

  15. Masking the Auditory Evoked Potential in TMS-EEG: A Comparison of Various Methods.

    PubMed

    ter Braack, Esther M; de Vos, Cecile C; van Putten, Michel J A M

    2015-05-01

    There is growing interest in combining transcranial magnetic stimulation (TMS) with electroencephalography (EEG). Because TMS pulses are accompanied by a clicking sound, it is very likely that part of the response in the EEG consists of an auditory evoked potential (AEP). Different methods have been applied to mask the sound of TMS. However, it is unclear which masking method is most effective in reducing the AEP. In this study we explore the presumed contribution of the AEP to the response and evaluate different ways to mask the TMS clicking sound. Twelve healthy subjects and one completely deaf subject participated in this study. Eight different masking conditions were evaluated in nine hearing subjects. The amplitude of the N100-P180 complex was compared between the different masking conditions. We were not able to completely suppress the N100-P180 when the coil was placed on top of the head. Using an earmuff or exposing the subjects to white or adapted noise caused a small but significant reduction in N100-P180 amplitude, but the largest reduction was achieved when combining a layer of foam, placed between coil and head, with white or adapted noise. The deaf subject also showed a N100-P180 complex. We conclude that both the TMS clicking sound and cortical activation by the magnetic pulse contribute to the N100-P180 amplitude. PMID:23996091

  16. Modal analysis of corticothalamic dynamics, electroencephalographic spectra, and evoked potentials.

    PubMed

    Robinson, P A; Loxley, P N; O'Connor, S C; Rennie, C J

    2001-04-01

    The effects of cortical boundary conditions and resulting modal aspects of continuum corticothalamic electrodynamics are explored, including feedbacks. Dispersion relations, electroencephalographic spectra, and stimulus response functions are calculated from the underlying physiology, and the effects of discrete mode structure are determined. Conditions under which modal effects are important are obtained, along with estimates of the point at which modal series can be truncated, and the limit in which only a single globally uniform mode need be retained. It is found that for physiologically plausible parameters only the lowest cortical spatial eigenmode together with the set of next-lowest modes can produce distinct modal structure in spectra and response functions, and then only at frequencies where corticothalamic resonances reduce dissipation to the point where the spatial eigenmodes are weakly damped. The continuum limit is found to be a good approximation, except at very low frequencies and, under some circumstances, near the alpha resonance. It is argued that the major electroencephalographic rhythms result from corticothalamic feedback resonances, but that cortical modal effects can contribute to weak substructure in the alpha resonance. This mechanism is compared and contrasted with purely cortical and pacemaker-based alternatives and testable predictions are formulated to enable experimental discrimination between these possibilities. PMID:11308879

  17. Effects of ketamine and propofol on motor evoked potentials elicited by intracranial microstimulation during deep brain stimulation

    PubMed Central

    Furmaga, Havan; Park, Hyun-Joo; Cooperrider, Jessica; Baker, Kenneth B.; Johnson, Matthew; Gale, John T.; Machado, Andre G.

    2014-01-01

    Few preclinical or clinical studies have evaluated the effect of anesthetics on motor evoked potentials (MEPs), either alone or in the presence of conditioning stimuli such as deep brain stimulation (DBS). In this study we evaluated the effects of two commonly used anesthetic agents, propofol and ketamine (KET), on MEPs elicited by intra-cortical microstimulation of the motor cortex in a rodent model with and without DBS of the dentatothalamocortical (DTC) pathway. The effects of propofol anesthesia on MEP amplitudes during DTC DBS were found to be highly dose dependent. Standard, but not high, dose propofol potentiated the facilitatory effects of 30 Hz DTC DBS on MEPs. This facilitation was sustained and phase-dependent indicating that, compared to high dose propofol, standard dose propofol has a beta-band excitatory effect on cortical networks. In contrast, KET anesthetic demonstrated a monotonic relationship with increasing frequencies of stimulation, such that the highest frequency of stimulation resulted in the greatest MEP amplitude. KET also showed phase dependency but less pronounced than standard dose propofol. The results underscore the importance of better understanding the complex effects of anesthetics on cortical networks and exogenous stimuli. Choice of anesthetic agents and dosing may significantly confound or even skew research outcomes, including experimentation in novel DBS indications and paradigms. PMID:24904312

  18. Cortically evoked responses of superior salivary nucleus neurons in the cat.

    PubMed

    Ishizuka, K; Murakami, T

    1989-01-01

    Salivation can be controlled by the inputs from the cerebral cortex as well as from the sensory nerves. However, there has been no detailed report so far on the inputs to superior salivatory nucleus (SSN) neurons from the cerebral cortex. The responses of SSN neurons to electrical stimulation of orbital and coronal gyri were investigated in ketamine anesthetized cats. A total of 56 SSN neurons were identified by the antidromic spike responses to stimulation of the right chorda tympani nerve. Their responsiveness to stimulation of the orbital and anterior coronal gyri and the lingual nerve at the ipsilateral side was tested. Thirty-five neurons (63%) responded with spikes to stimulation of the orbital and/or coronal gyri. They were also activated by stimulation of the lingual nerve. Other eleven neurons (20%) received the inputs from the lingual nerve only. The remaining 10 neurons (17%) failed to respond to stimulation of either the cerebral cortex or the lingual nerve. The mean latencies of the responses to stimulation of the orbital gyrus, coronal gyrus and lingual nerve were 29.0 ms (n = 28), 22.7 ms (n = 33) and 10.2 ms (n = 46), respectively. In this study, the excitatory inputs converging from the cerebral cortex and the lingual nerve, found in 63% of SSN neurons, could play an important role in submandibular and sublingual salivation. Cortically induced salivation, in particular, may be involved in salivary secretion in the conditioned reflexes as well as in mastication. PMID:2635781

  19. Effects of calcium antagonists on KCl-evoked calcium uptake by rat cortical synaptosomes.

    PubMed

    Wei, J W; Chiang, D H

    1986-01-01

    A series of calcium antagonists were used to study their blocking effect on high potassium-induced calcium uptake into rat cortical synaptosomes; these antagonists were classified into five groups: dihydropyridine group (i.e. nifedipine and nitrendipine), benzothiazepine group (i.e. diltiazem), phenylalkylamine group (i.e. verapamil and D600), phenothiazine group (i.e. trifluoperazine) and diphenylpiperazine group (i.e. flunarizine and cinnarizine). Voltage-dependent 45Ca2+-uptake into this fraction was measured after 20 sec KCl-induced depolarization. The ID30 values of the above-mentioned antagonists affecting 45Ca2+-uptake were calculated to be nitrendipine (80 microM), nifedipine (100 microM), verapamil (50 microM), D600 (15 microM), diltiazem (70 microM), trifluoperazine (7 microM), cinnarizine (1.2 microM) and flunarizine (0.7 microM). Our results reveal that in rat brain synaptosomal fractions, calcium influx via the voltage-gated calcium channel appears to be more sensitive to diphenylpiperazine and phenothiazine groups; whereas, phenylalkylamine, benzothiazepine and dihydropyridine groups were relatively insensitive. This contrasts with the well known data obtained from vascular smooth muscle, in which the dihydropyridine group is the most sensitive of all the groups studied. Our results suggest that calcium channels in neuronal tissue are most likely different from those in non-neuronal tissue. PMID:3721183

  20. EVOKED POTENTIALS AS INDICES OF ADAPTATION IN THE SOMATOSENSORY SYSTEM IN HUMANS: A REVIEW AND PROSPECTUS

    EPA Science Inventory

    Population-level behavior of large neural aggregates can be efficiently monitored by corresponding population-level indices such as somatosensory evoked potentials (SEPs). The literature reviewed clearly indicates that SEPs undergo systematic and often marked changes under condit...

  1. THE USE OF VISUAL AND CHEMOSENSORY EVOKED POTENTIALS IN ENVIRONMENTAL AND OCCUPATIONAL HEALTH

    EPA Science Inventory

    The application of visual (VEP) and chemosensory evoked potentials (CSEP) in occupational and environmental health is briefly reviewed. EPs have been used extensively in experimental neurotoxicology and play an increasing role in human neurotoxicity testing. he similarity of VEP ...

  2. Report of Seizure Following Intraoperative Monitoring of Transcranial Motor Evoked Potentials

    PubMed Central

    Davis, Scott F.; Altstadt, Thomas; Flores, Rick; Kaye, Alan; Oremus, Glenn

    2013-01-01

    Background Transcranial motor evoked potentials are used to detect iatrogenic injury to the corticospinal tracts and vascular territory of the anterior spinal artery. Tongue and lip lacerations are the most common complication of this modality. Theoretical complications include cardiac arrhythmia and seizure although there are no published reports of either. Case Report We report a case of postoperative seizure following motor evoked potential testing in a patient without a seizure history. Although anecdotal reports exist, ours is the first known published report of seizure following transcranial electrical stimulation. Conclusion The intent of this novel report is to encourage the use of anesthetic regimens that raise seizure threshold, decrease stimulation threshold, and increase the specificity of motor evoked potentials. Providers should be prepared to treat intraoperative or perioperative seizure activity when the monitoring protocol includes transcranial motor evoked potentials. PMID:24358008

  3. Evaluation of brain function in acute carbon monoxide poisoning with multimodality evoked potentials

    SciTech Connect

    He, Fengsheng; Liu, Xibao; Yang, Shi; Zhang, Shoulin ); Xu, Guanghua; Fang, Guangchai; Pan, Xiaowen )

    1993-02-01

    The median nerve somatosensory evoked potentials (SEP), pattern reversal visual evoked potentials (VEP), and brain stem auditory evoked potentials (BAEP) were studied in 109 healthy adults and in 88 patients with acute carbon monoxide (CO) poisoning. The upper limits for normal values of peak and interpeak latencies of multimodalities of evoked potentials in the reference group were established by a stepwise multiple regression analysis. SEP changes selectively affecting N32 and N60 were found in 78.8% of patients. There was prolonged PI00 latency of VEP in 58.2% of the cases examined. The prevalence of BAEP abnormalities in comatose patients (36%) was significantly higher than that (8.6%) in conscious patients. BAEP abnormalities were most frequently seen in comatose patients who had diminished brain stem reflexes (77.8%). It has been found that a consistent abnormality involving N2O and subsequent peaks in SEP, a remarkable prolongation of PI00 latency in VEP, or a prolongation of Ill-V interpeak latency in BAEP as well as the reoccurrence of evoked potential abnormalities after initial recovery all indicate unfavorable outcomes in patients with acute CO poisoning. The multimodality evoked potentials have proved to be sensitive indicators in the evaluation of brain dysfunction and in the prediction of prognosis of acute CO poisoning and the development of delayed encephalopathy. 16 refs., 4 figs., 6 tabs.

  4. From cognitive networks to seizures: Stimulus evoked dynamics in a coupled cortical network

    NASA Astrophysics Data System (ADS)

    Lee, Jaejin; Ermentrout, Bard; Bodner, Mark

    2013-12-01

    Epilepsy is one of the most common neuropathologies worldwide. Seizures arising in epilepsy or in seizure disorders are characterized generally by uncontrolled spread of excitation and electrical activity to a limited region or even over the entire cortex. While it is generally accepted that abnormal excessive firing and synchronization of neuron populations lead to seizures, little is known about the precise mechanisms underlying human epileptic seizures, the mechanisms of transitions from normal to paroxysmal activity, or about how seizures spread. Further complication arises in that seizures do not occur with a single type of dynamics but as many different phenotypes and genotypes with a range of patterns, synchronous oscillations, and time courses. The concept of preventing, terminating, or modulating seizures and/or paroxysmal activity through stimulation of brain has also received considerable attention. The ability of such stimulation to prevent or modulate such pathological activity may depend on identifiable parameters. In this work, firing rate networks with inhibitory and excitatory populations were modeled. Network parameters were chosen to model normal working memory behaviors. Two different models of cognitive activity were developed. The first model consists of a single network corresponding to a local area of the brain. The second incorporates two networks connected through sparser recurrent excitatory connectivity with transmission delays ranging from approximately 3 ms within local populations to 15 ms between populations residing in different cortical areas. The effect of excitatory stimulation to activate working memory behavior through selective persistent activation of populations is examined in the models, and the conditions and transition mechanisms through which that selective activation breaks down producing spreading paroxysmal activity and seizure states are characterized. Specifically, we determine critical parameters and architectural

  5. Auditory brainstem and cortical potentials following bone-anchored hearing aid stimulation.

    PubMed

    Rahne, Torsten; Ehelebe, Thomas; Rasinski, Christine; Götze, Gerrit

    2010-11-30

    Patients suffering from conductive or mixed hearing loss and Single-Sided Deafness may benefit from implantable hearing devices relying on bone conducted auditory stimulation. However, with only passively cooperative patients, objective methods are needed to estimate the aided and unaided pure-tone audiogram. This study focuses on the feasibility aspect of an electrophysiological determination of the hearing thresholds with bone-anchored hearing aid stimulation. Therefore, 10 normal-hearing subjects were provided with a Baha Intenso (Cochlear Ltd.) which was temporarily connected to the Baha Softband (Cochlear Ltd.). Auditory evoked potentials were measured by auditory stimulation paradigm used in clinical routine. The amplitudes, latencies, and thresholds of the resulting auditory brainstem responses (ABR) and the cortically evoked responses (CAEP) were correlated with the respective responses without the use of the Baha Intenso. The recording of ABR and CAEP by delivering the stimuli to the Baha results in response waveforms which are comparable to those evoked by earphone stimulation and appears appropriate to be measured using the Baha Intenso as stimulator. At the ABR recordings a stimulus artifact at higher stimulation levels and a constant latency shift caused by the Baha Intenso has to be considered. The CAEP recording appeared promising as a frequency specific objective method to approve the fitting of bone-anchored hearing aids. At all measurements, the ABR and CAEP thresholds seem to be consistent with the normal hearing of the investigated participants. Thus, a recording of auditory evoked potentials using a Baha is in general possible if specific limitations are considered. PMID:20875458

  6. Vertex evoked potentials in a rating-scale detection task - Relation to signal probability

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Squires, N. K.; Hillyard, S. A.

    1975-01-01

    Results of vertex-evoked potential studies conducted to determine how decision confidence level and decision probability interact to determine P3 amplitude for both signal-present and signal-absent decisions. They support the contention that the form of the vertex-evoked response is closely correlated with the subject's psychophysical response regarding the presence or absence of a threshold-level signal.

  7. 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. PMID:23785166

  8. Cortical activity evoked by inoculation needle prick in infants up to one-year old

    PubMed Central

    Verriotis, Madeleine; Fabrizi, Lorenzo; Lee, Amy; Ledwidge, Sheryl; Meek, Judith; Fitzgerald, Maria

    2015-01-01

    Abstract Inoculation is one of the first and most common experiences of procedural pain in infancy. However, little is known about how needle puncture pain is processed by the central nervous system in children. In this study, we describe for the first time the event-related activity in the infant brain during routine inoculation using electroencephalography. Fifteen healthy term-born infants aged 1 to 2 months (n = 12) or 12 months (n = 5) were studied in an outpatient clinic. Pain behavior was scored using the Modified Behavioral Pain Scale. A distinct inoculation event–related vertex potential, consisting of 2 late negative-positive complexes, was observable in single trials after needle contact with the skin. The amplitude of both negative-positive components was significantly greater in the 12-month group. Both inoculation event–related potential amplitude and behavioral pain scores increased with age but the 2 measures were not correlated with each other. These components are the first recordings of brain activity in response to real-life needle pain in infants up to a year old. They provide new evidence of postnatal nociceptive processing and, combined with more traditional behavioral pain scores, offer a potentially more sensitive measure for testing the efficacy of analgesic protocols in this age group. PMID:25599443

  9. Cortical activity evoked by inoculation needle prick in infants up to one-year old.

    PubMed

    Verriotis, Madeleine; Fabrizi, Lorenzo; Lee, Amy; Ledwidge, Sheryl; Meek, Judith; Fitzgerald, Maria

    2015-02-01

    Inoculation is one of the first and most common experiences of procedural pain in infancy. However, little is known about how needle puncture pain is processed by the central nervous system in children. In this study, we describe for the first time the event-related activity in the infant brain during routine inoculation using electroencephalography. Fifteen healthy term-born infants aged 1 to 2 months (n = 12) or 12 months (n = 5) were studied in an outpatient clinic. Pain behavior was scored using the Modified Behavioral Pain Scale. A distinct inoculation event-related vertex potential, consisting of 2 late negative-positive complexes, was observable in single trials after needle contact with the skin. The amplitude of both negative-positive components was significantly greater in the 12-month group. Both inoculation event-related potential amplitude and behavioral pain scores increased with age but the 2 measures were not correlated with each other. These components are the first recordings of brain activity in response to real-life needle pain in infants up to a year old. They provide new evidence of postnatal nociceptive processing and, combined with more traditional behavioral pain scores, offer a potentially more sensitive measure for testing the efficacy of analgesic protocols in this age group. PMID:25599443

  10. One Size Fits All? Slow Cortical Potentials Neurofeedback: A Review

    ERIC Educational Resources Information Center

    Mayer, Kerstin; Wyckoff, Sarah N.; Strehl, Ute

    2013-01-01

    Objective: The intent of this manuscript was to review all published studies on slow cortical potentials (SCP) neurofeedback for the treatment of ADHD, with emphasis on neurophysiological rationale, study design, protocol, outcomes, and limitations. Method: For review, PubMed, MEDLINE, ERIC, and Google Scholar searches identified six studies and…

  11. Low level Methylmercury enhances CNTF-evoked STAT3 signaling and glial differentiation in cultured cortical progenitor cells

    PubMed Central

    Jebbett, Nathan J.; Hamilton, Joshua W.; Rand, Matthew D.; Eckenstein, Felix

    2013-01-01

    Although many previous investigations have studied how mercury compounds cause cell death, sub-cytotoxic levels may affect mechanisms essential for the proper development of the nervous system. The present study investigates whether low doses of methylmercury (MeHg) and mercury chloride (HgCl2) can modulate the activity of JAK/STAT signaling, a pathway that promotes gliogenesis. We report that sub-cytotoxic doses of MeHg enhance ciliary neurotrophic factor (CNTF) evoked STAT3 phosphorylation in human SH-SY5Y neuroblastoma and mouse cortical neural progenitor cells (NPCs). This effect is specific for MeHg, since HgCl2 fails to enhance JAK/STAT signaling. Exposing NPCs to these low doses of MeHg (30-300 nM) enhances CNTF-induced expression of STAT3-target genes such as glial fibrillary acidic protein (GFAP) and suppressors of cytokine signaling 3 (SOCS3), and increases the proportion of cells expressing GFAP following two days of differentiation. Higher, near-cytotoxic concentrations of MeHg and HgCl2 inhibit STAT3 phosphorylation and lead to increased production of superoxide. Lower concentrations of MeHg effective in enhancing JAK/STAT signaling (30 nM) do not result in a detectable increase in superoxide nor increased expression of the oxidant-responsive genes, heme oxygenase 1, heat shock protein A5 and sirtuin 1. These findings suggest that low concentrations of MeHg inappropriately enhance STAT3 phosphorylation and glial differentiation, and that the mechanism causing this enhancement is distinct from the reactive oxygen species -associated cell death observed at higher concentrations of MeHg and HgCl2. PMID:23845766

  12. Prognostic value of evoked and event-related potentials in moderate to severe brain injury.

    PubMed

    Lew, Henry L; Poole, John H; Castaneda, Annabel; Salerno, Rose Marie; Gray, Max

    2006-01-01

    Clinicians are often expected to project patients' clinical outcomes to allow effective planning for future care. This can be a challenge in patients with moderate to severe traumatic brain injury (TBI) who are often unable to participate reliably in clinical evaluations. With recent advances in computer instrumentation and signal processing, evoked potentials and event-related potentials show increasing promise as powerful tools for prognosticating the trajectory of recovery and ultimate outcome from the TBI. Short- and middle-latency evoked potentials can now effectively predict coma outcomes in patients with acute TBI. Long-latency event-related potential components hold promise in predicting recovery of higher order cognitive abilities. PMID:16915010

  13. The combined monitoring of brain stem auditory evoked potentials and intracranial pressure in coma. A study of 57 patients.

    PubMed Central

    García-Larrea, L; Artru, F; Bertrand, O; Pernier, J; Mauguière, F

    1992-01-01

    Continuous monitoring of brainstem auditory evoked potentials (BAEPs) was carried out in 57 comatose patients for periods ranging from 5 hours to 13 days. In 53 cases intracranial pressure (ICP) was also simultaneously monitored. The study of relative changes of evoked potentials over time proved more relevant to prognosis than the mere consideration of "statistical normality" of waveforms; thus progressive degradation of the BAEPs was associated with a bad outcome even if the responses remained within normal limits. Contrary to previous reports, a normal BAEP obtained during the second week of coma did not necessarily indicate a good vital outcome; it could, however, do so in cases with a low probability of secondary insults. The simultaneous study of BAEPs and ICP showed that apparently significant (greater than 40 mm Hg) acute rises in ICP were not always followed by BAEP changes. The stability of BAEP's despite "significant" ICP rises was associated in our patients with a high probability of survival, while prolongation of central latency of BAEPs in response to ICP modifications was almost invariably followed by brain death. Continuous monitoring of brainstem responses provided a useful physiological counterpart to physical parameters such as ICP. Serial recording of cortical EPs should be added to BAEP monitoring to permit the early detection of rostrocaudal deterioration. Images PMID:1402970

  14. Intraoperative monitoring of spinal cord function using motor evoked potentials via transcutaneous epidural electrode during anterior cervical spinal surgery.

    PubMed

    Gokaslan, Z L; Samudrala, S; Deletis, V; Wildrick, D M; Cooper, P R

    1997-08-01

    Because false-positive results are not infrequent when monitoring somatosensory evoked potentials during surgery, monitoring of motor evoked potentials (MEPs) has been proposed and successfully used during the removal of spinal cord tumors. However, this often requires direct visual placement of an epidural electrode after a laminectomy. We evaluated the use of MEPs, recorded via a transcutaneously placed epidural electrode, to monitor motor pathway functional integrity during surgery on the anterior cervical spine. Sixteen patients underwent anterior cervical vertebral decompression and fusion for cervical myelopathy and/or radiculopathy. Before surgery, an epidural monitoring electrode was placed transcutaneously at the midthoracic level and was used to record MEPs after transcranial cortical electrical stimulation. Electrode placement was successful in all patients but one, and satisfactory baseline spinal MEPs were obtained except for one patient who had cerebral palsy with significant motor dysfunction. Patients showed no significant changes in spinal MEPs during surgery, and all had baseline or better motor function postoperatively. None had complications from epidural electrode placement or electrical stimulation. We conclude that motor pathways can be monitored safely during anterior cervical spinal surgery using spinal MEPs recorded via a transcutaneously placed epidural electrode, that MEP preservation during surgery correlates with good postoperative motor function, and that cerebral palsy patients may possess too few functional motor fibers to allow MEP recording. PMID:9278914

  15. Immediate plasticity in the motor pathways after spinal cord hemisection: implications for transcranial magnetic motor-evoked potentials.

    PubMed

    Fujiki, Minoru; Kobayashi, Hidenori; Inoue, Ryo; Ishii, Keisuke

    2004-06-01

    The present study evaluates motor functional recovery after C2 spinal cord hemisection with or without contralateral brachial root transection, which causes a condition that is similar to the crossed phrenic phenomenon on rats. Descending motor pathways, including the reticulospinal extrapyramidal tract and corticospinal pyramidal tracts, were evaluated by transcranial magnetic motor-evoked potentials (mMEPs) and direct cortical electrical motor-evoked potentials (eMEP), respectively. All MEPs recorded from the left forelimb were abolished immediately after the left C2 hemisection. Left mMEPs recovered dramatically immediately after contralateral right brachial root transection. Corticospinal eMEPs never recovered, regardless of transection. The facilitation of mMEPs in animals that had undergone combined contralateral root transection was well correlated with open-field behavioral motor performance. Both electrophysiological and neurological facilitations were significantly attenuated by the selective serotonin synthesis inhibitor para-chlorophenylalanine (p-CPA). These results suggest that serotonergic reticulospinal fibers located contralateral to hemisection contribute to the behavioral and electrophysiological improvement that immediately follows spinal cord injury (SCI). PMID:15144873

  16. Single-Trial Extraction of Pure Somatosensory Evoked Potential Based on Expectation Maximization Approach.

    PubMed

    Chen, Wei; Chang, Chunqi; Hu, Yong

    2016-01-01

    It is of great importance for intraoperative monitoring to accurately extract somatosensory evoked potentials (SEPs) and track its changes fast. Currently, multi-trial averaging is widely adopted for SEP signal extraction. However, because of the loss of variations related to SEP features across different trials, the estimated SEPs in such a way are not suitable for the purpose of real-time monitoring of every single trial of SEP. In order to handle this issue, a number of single-trial SEP extraction approaches have been developed in the literature, such as ARX and SOBI, but most of them have their performance limited due to not sufficient utilization of multi-trial and multi-condition structures of the signals. In this paper, a novel Bayesian model of SEP signals is proposed to make systemic use of multi-trial and multi-condition priors and other structural information in the signal by integrating both a cortical source propagation model and a SEP basis components model, and an Expectation Maximization (EM) algorithm is developed for single-trial SEP estimation under this model. Numerical simulations demonstrate that the developed method can provide reasonably good single-trial estimations of SEP as long as signal-to-noise ratio (SNR) of the measurements is no worse than -25 dB. The effectiveness of the proposed method is further verified by its application to real SEP measurements of a number of different subjects during spinal surgeries. It is observed that using the proposed approach the main SEP features (i.e., latencies) can be reliably estimated at single-trial basis, and thus the variation of latencies in different trials can be traced, which provides a solid support for surgical intraoperative monitoring. PMID:26742104

  17. Effects of symptomatic treatments on cutaneous hyperalgesia and laser evoked potentials during migraine attack.

    PubMed

    de Tommaso, M; Losito, L; Libro, G; Guido, M; Di Fruscolo, O; Sardaro, M; Sciruicchio, V; Lamberti, P; Livrea, P

    2005-05-01

    Previously an amplitude enhancement of laser evoked potentials (LEPs) was detected during migraine attack: we further examined pain threshold to CO2 laser stimuli and LEPs during attacks, evaluating the effect of almotriptan, lysine-acetylsalicylate and placebo treatment on cutaneous hyperalgesia to thermal stimuli delivered by CO2 laser and on LEP components. Eighteen patients suffering from migraine without aura were analysed. They were divided into three groups of six patients each, randomly assigned to lysine acetyl-salicylate, almotriptan or placebo treatments. The supraorbital zones and the dorsum of the hand were stimulated on both the symptomatic and not symptomatic side in all patients. The LEPs were recorded by 25 scalp electrodes. During attacks, the P2 wave was significantly enhanced; the amplitude of the P2 component obtained by the stimulation of the supraorbital zone during the attack on the side of the headache was significantly correlated with the intensity of pain and the frequency of headache. Both almotriptan and lysine acetyl-salicylate significantly reduced the P2 amplitude but they showed no effects on hyperalgesia to laser stimulation; headache relief following therapy was correlated with the reduction of the P2 amplitude. The cortical elaboration of laser-induced experimental pain seemed increased during migraine attack, and the severity of headache was mainly related to the increase of the later LEPs components expressing the attentive and emotive compounds of suffering. Reversion of this process appeared to be primarily responsible for the efficacy of drugs in treating migraine, though both almotriptan and lysine-acetil salicilate seemed to have no effect in reducing sensitization at second and third order nociceptive neurons. PMID:15839851

  18. The use of magnetic motor evoked potentials in horses with cervical spinal cord disease.

    PubMed

    Nollet, H; Deprez, P; Van Ham, L; Verschooten, F; Vanderstraeten, G

    2002-03-01

    The aim of this study was to investigate the use of magnetic motor evoked potentials as an ancillary diagnostic test in horses with cervical cord lesions. Transcranial magnetic stimulation was performed in 12 ataxic horses and the results of the evoked responses were compared to those found in normal horses. The latency and peak-to-peak amplitude of the potentials in the 12 ataxic horses were significantly different from those measured in normal horses. The configuration of the abnormal potentials was also polyphasic. Normalisation of the evoked potentials occurred in none of the horses, presented after a period of clinical improvement. These findings demonstrate that the technique is also able to detect lesions in horses with subtle clinical signs of incoordination. Magnetic transcranial stimulation is a valuable ancillary test to assess the integrity of the motor tracts. The technique is painless and safe and shows good sensitivity to detect lesions along the descending motor pathways. PMID:11902758

  19. Effects of sedative and hypnotic drug combinations on transcranial magnetic motor evoked potential, bispectral index and ARX-derived auditory evoked potential index in dogs.

    PubMed

    Van Soens, Iris; Struys, Michel M; Polis, Ingeborgh E; Tshamala, Mulenda; Nollet, Heidi; Bhatti, Sofie F; Van Ham, Luc M

    2009-08-01

    Relationships between onset latency and peak-to-peak amplitude of magnetic motor evoked potentials (MMEP) after transcranial magnetic stimulation (TMS), together with the electroencephalographic parameters bispectral analysis index (BIS) and the autoregressive model with exogenous input (ARX)-derived auditory evoked potential index (AAI) were explored during different sedative and hypnotic drug combinations in six dogs. TMS was performed under sedation with acepromazine/methadone or medetomidine and after a single bolus injection of propofol or etomidate. Data for BIS and AAI were continuously collected during the periods of treatment with the hypnotic drugs. Changes in BIS and AAI during both periods were not statistically correlated with changes in onset latencies and peak-to-peak amplitudes of MMEP after TMS. Therefore, both electroencephalographic techniques are of limited use in titrating sedation and anaesthesia during TMS in the dog. PMID:18682332

  20. Evaluation of the dermatomal somatosensory evoked potential in the diagnosis of lumbo-sacral root compression.

    PubMed Central

    Katifi, H A; Sedgwick, E M

    1987-01-01

    The dermatomal somatosensory evoked potential from the lumbo-sacral dermatomes was recorded from 21 patients with radiographically and surgically (20) proven lumbo-sacral root compression due to prolapsed intervertebral disc or canal stenosis. The potential was abnormal in 19 of the 20 surgically proven cases. The dermatomal somatosensory evoked potential is as accurate as myelography for diagnosis but has the advantage of being non-invasive and repeatable. It provides useful additional diagnostic and pathophysiological information about lumbo-sacral root compression. PMID:3668570

  1. [Influence of GABA(C)-Receptor Antagonist on Formation of Evoked Potentials in Columns of the Rat Somatosensory Cortex].

    PubMed

    Matukhno, A E; Lysenko, L V; Andreeva, Y V; Sukhov, A G

    2015-01-01

    Microelectrode studies of evoked potentials (EP) in neuronal column of rats barrel cortex show activating action of selective GABA(C)-receptor antagonist 1,2,5,6-tetrahydropyridin-4-yl-methylphosphinic acid (TPMPA) mainly on secondary components of EP of supragranular afferent layers of column compared to the efferent infragranular layers. These data suggest localization of GABA(C)-receptors on pre- synaptic terminals of thalamo-cortical glutamatergic afferents and ascending apical dendrites of pyramidal cells. A blockade of GABA(C)-receptors with the selective antagonist TPM PA leads to dose-dependent afferent depolarization with development of presynaptic inhibition and suppression of primary components of EP GABA(C)-receptors blocker produces different effects on secondary components of EP in supragranular layers of the cortex caused by the development of neuronal after hyperpolarization followed by high-amplitude primary response and afterdepolarization followed by low-amplitude primary responses with subsequent activation of different voltage-gated channels and formation of different level of cortical direct current potential gradients. PMID:26841661

  2. Multiprocessing computer system for sensory evoked potentials and EEG spectral analysis for clinical neurophysiology laboratory.

    PubMed

    Steben, J D; Streletz, L J; Fariello, R G

    1985-12-01

    A general-purpose minicomputer has been adapted and interfaced for the averaging and analysis of clinical evoked potentials and for compressed spectral arrays (CSA) of the routine EEG. In the first 2 years of operation, over 1,000 routine clinical studies of visual evoked potentials (VEP) and brainstem auditory evoked potentials (BAEP) have been performed with it, as well as over 100 CSAs and a variety of special and research studies. The CSA modality gives comparative frequency-domain pictures of left and right hemisphere power. An attached graphics terminal gives a live cumulative display of the EP and CSA. In addition, the system has automated and comprehensive physician-interactive graphics analysis and report generation capabilities. The reports are finalized versions used in the patient's chart, minimizing clerical efforts. PMID:3841553

  3. Lumbosacral evoked potentials and vesicourethral function in patients with chronic suprasacral spinal cord injury.

    PubMed Central

    Lucas, M G; Thomas, D G

    1990-01-01

    Persistent detrusor acontractility despite normal somatic reflex activity in some patients with high spinal cord injury is an enigma. Previous work has suggested disordered integration of afferent activity in sacral roots or the sacral spinal cord. Forty male patients with chronic stable suprasacral cord lesions were studied by filling and voiding videocystometrography, and recording lumbosacral evoked potentials from posterior tibial nerve stimulation. Only five of 15 patients with decreased detrusor contractility had abnormal lumbosacral evoked potentials. Similar abnormalities were found in four of 11 patients with efficient hyperreflexic bladders. The finding of normal lumbosacral evoked potentials in the majority of patients with suprasacral cord injuries and decreased detrusor contractility supports the argument that the pathophysiology of this specific form of neurogenic bladder dysfunction is multifactorial. PMID:2283530

  4. Vertex evoked potentials in a rating-scale detection task: Relation to signal probability

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Squires, N. K.; Hillyard, S. A.

    1974-01-01

    Vertex evoked potentials were recorded from human subjects performing in an auditory detection task with rating scale responses. Three values of a priori probability of signal presentation were tested. The amplitudes of the N1 and P3 components of the vertex potential associated with correct detections of the signal were found to be systematically related to the strictness of the response criterion and independent of variations in a priori signal probability. No similar evoked potential components were found associated with signal absent judgements (misses and correct rejections) regardless of the confidence level of the judgement or signal probability. These results strongly support the contention that the form of the vertex evoked response is closely correlated with the subject's psychophysical decision regarding the presence or absence of a threshold level signal.

  5. Visual evoked potentials monitoring in a case of transient post-operative visual loss.

    PubMed

    Capon, Marie; Boven, Michel Van; van Pesch, Vincent; Hantson, Philippe

    2016-08-01

    Post-operative visual loss (POVL) is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations. PMID:27601743

  6. Visual evoked potentials monitoring in a case of transient post-operative visual loss

    PubMed Central

    Capon, Marie; Boven, Michel Van; van Pesch, Vincent; Hantson, Philippe

    2016-01-01

    Post-operative visual loss (POVL) is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations. PMID:27601743

  7. A novel ring electrode setup for the recording of somatosensory evoked potentials during transcranial direct current stimulation (tDCS).

    PubMed

    Sehm, Bernhard; Hoff, Maike; Gundlach, Christopher; Taubert, Marco; Conde, Virginia; Villringer, Arno; Ragert, Patrick

    2013-01-30

    Transcranial direct current stimulation (tDCS) modulates cortical excitability thereby influencing behavior and learning. While previous studies focused on tDCS after-effects, limited information about "online" tDCS effects is available. This in turn is an important prerequisite to better characterize and/or optimize tDCS effects. Here, we aimed to explore the feasibility of recording low-artifact somatosensory evoked potentials (SEPs) during tDCS using a novel ring electrode setup. We recorded SEP before, during and after 10 min of anodal or sham tDCS using a full-band direct current (DC) EEG system in a total number of 3 subjects. SEPs were recorded in the bore of the tDCS ring electrode. Using this approach, no tDCS-induced artifacts could be observed after the application of a standard EEG filter. This new setup might help to better characterize how tDCS alters evoked brain responses thus providing novel insight into underlying physiological effects during stimulation. PMID:23103376

  8. Simulated generation of evoked potentials components using networks with distinct excitatory and inhibitory neurons.

    PubMed

    Ventouras, E; Uzunoglu, N K; Koutsouris, D; Papageorgiou, C; Rabavilas, A; Stefanis, C

    2000-09-01

    Long latency evoked potentials (EP's) are electrical potentials related to brain information processing mechanisms. In this paper, three-layered neurophysiologically based artificial neural network model is presented whose neurons obey to Dale's law. The first two layers of the network can memorize and recall sparsely coded patterns, oscillating at biologically plausible frequencies. Excitatory low-pass filtering synapses, from the second to the third layer, create evoked current dipoles, when the network retrieves memories related to stimuli. Based on psychophysiological indications, simulated intracranial dipoles are straightforwardly transformed into long latency EP components such as N100 and P300 that match laboratory-measured scalp EP's. PMID:11026594

  9. Change in Speech Perception and Auditory Evoked Potentials over Time after Unilateral Cochlear Implantation in Postlingually Deaf Adults.

    PubMed

    Purdy, Suzanne C; Kelly, Andrea S

    2016-02-01

    Speech perception varies widely across cochlear implant (CI) users and typically improves over time after implantation. There is also some evidence for improved auditory evoked potentials (shorter latencies, larger amplitudes) after implantation but few longitudinal studies have examined the relationship between behavioral and evoked potential measures after implantation in postlingually deaf adults. The relationship between speech perception and auditory evoked potentials was investigated in newly implanted cochlear implant users from the day of implant activation to 9 months postimplantation, on five occasions, in 10 adults age 27 to 57 years who had been bilaterally profoundly deaf for 1 to 30 years prior to receiving a unilateral CI24 cochlear implant. Changes over time in middle latency response (MLR), mismatch negativity, and obligatory cortical auditory evoked potentials and word and sentence speech perception scores were examined. Speech perception improved significantly over the 9-month period. MLRs varied and showed no consistent change over time. Three participants aged in their 50s had absent MLRs. The pattern of change in N1 amplitudes over the five visits varied across participants. P2 area increased significantly for 1,000- and 4,000-Hz tones but not for 250 Hz. The greatest change in P2 area occurred after 6 months of implant experience. Although there was a trend for mismatch negativity peak latency to reduce and width to increase after 3 months of implant experience, there was considerable variability and these changes were not significant. Only 60% of participants had a detectable mismatch initially; this increased to 100% at 9 months. The continued change in P2 area over the period evaluated, with a trend for greater change for right hemisphere recordings, is consistent with the pattern of incremental change in speech perception scores over time. MLR, N1, and mismatch negativity changes were inconsistent and hence P2 may be a more robust measure

  10. Single Trial Predictors for Gating Motor-Imagery Brain-Computer Interfaces Based on Sensorimotor Rhythm and Visual Evoked Potentials

    PubMed Central

    Geronimo, Andrew; Kamrunnahar, Mst; Schiff, Steven J.

    2016-01-01

    For brain-computer interfaces (BCIs) that utilize visual cues to direct the user, the neural signals extracted by the computer are representative of ongoing processes, visual evoked responses, and voluntary modulation. We proposed to use three brain signatures for predicting success on a single trial of a BCI task. The first two features, the amplitude and phase of the pre-trial mu amplitude, were chosen as a correlate for cortical excitability. The remaining feature, related to the visually evoked response to the cue, served as a possible measure of fixation and attention to the task. Of these three features, mu rhythm amplitude over the central electrodes at the time of cue presentation and to a lesser extent the single trial visual evoked response were correlated with the success on the subsequent imagery task. Despite the potential for gating trials using these features, an offline gating simulation was limited in its ability to produce an increase in device throughput. This discrepancy highlights a distinction between the identification of predictive features, and the use of this knowledge in an online BCI. Using such a system, we cannot assume that the user will respond similarly when faced with a scenario where feedback is altered by trials that are gated on a regular basis. The results of this study suggest the possibility of using individualized, pre-task neural signatures for personalized, and asynchronous (self-paced) BCI applications, although these effects need to be quantified in a real-time adaptive scenario in a future study. PMID:27199630

  11. Steady-state visual evoked potentials: distributed local sources and wave-like dynamics are sensitive to flicker frequency

    PubMed Central

    Srinivasan, Ramesh; Bibi, F. Alouani; Nunez, Paul L.

    2007-01-01

    Steady-state visual evoked potentials (SSVEPs) are used in cognitive and clinical studies of brain function because of excellent signal-to-noise ratios and relative immunity to artifacts. SSVEPs also provide a means to characterize preferred frequencies of neocortical dynamic processes. In this study, SSVEPs were recorded with 110 electrodes while subjects viewed random dot patterns flickered between 3 and 30 Hz. Peaks in SSVEP power were observed at delta (3 Hz), lower alpha (7 and 8 Hz), and upper alpha band (12 and 13 Hz) frequencies; the spatial distribution of SSVEP power is also strongly dependent on the input frequency suggesting cortical resonances. We characterized the cortical sources that generate SSVEPs at different input frequencies by applying surface Laplacians and spatial spectral analysis. Laplacian SSVEPs recorded are sensitive to small changes (1–2 Hz) in the input frequency at occipital and parietal electrodes indicating distinct local sources. At 10 Hz, local source activity occurs in multiple cortical regions; Laplacian SSVEPs are also observed in lateral frontal electrodes. Laplacian SSVEPs are negligible at many frontal electrodes that elicit strong potential SSVEPs at delta, lower alpha, and upper alpha bands. One-dimensional (anterior-posterior) spatial spectra indicate that distinct large-scale source distributions contribute SSVEP power in these frequency bands. In the upper alpha band, spatial spectra indicate the presence of long-wavelength (> 15 cm) traveling waves propagating from occipital to prefrontal electrodes. In the delta and lower alpha band, spatial spectra indicate that long-wavelength source distributions over posterior and anterior regions form standing-wave patterns. These results suggest that the SSVEP is generated by both (relatively stationary) localized sources and distributed sources that exhibit characteristics of wave phenomena. PMID:16544207

  12. Dynamics of visual evoked potentials (VEPs) in the guinea pig visual cortex under laser light irradiation of the retina

    NASA Astrophysics Data System (ADS)

    Bondar, Galina G.

    1995-05-01

    Influence of laser irradiation (wavelength 632.8 nM) of the retina on visual evoked potentials (VEPs) in response to flashes of diffuse light have been studied. VEPs were recorded by tungsten-in-glass semimicroelectrode blocks at 700 (mu) M below cortical surface. It was revealed that VEPs were modified at all used doses of laser irradiation (power at cornea from 0.5 to 17 mW, exposure from 0.1 to 1000 s). During the initial 5 - 70 s of laser irradiation VEPs completely disappeared. After this silent period there appeared VEPs splitting into 2 - 4 distinct components and strong suppression or disappearance of VEPs first negative wave was observed. When laser irradiation was switched off VEPs negative waves were restored while the amplitude of splitting components was diminished. Restoration (frequently incomplete) of VEPs passed through a phase of increased negative wave amplitude. After the dose of laser irradiation was increased, this phase was followed by periodic changes in the amplitude of all VEPs components. Besides, the cortical zone that displayed the disturbances of the VEPs, became more extended. Long-lasting disturbances of VEPs occurred at irradiation doses close to those described in literature for ophthalmologically detected injuries. It is supposed that reversible (functional) disturbances may be identified by means of the above-mentioned phenomena. The discovered phenomena suit well the scheme which supposes disbalance and disinhibition of lateral connections between the irradiated retinal loci and the surrounding site.

  13. Serotonergic Dysfunction in Patients with Bipolar Disorder Assessed by the Loudness Dependence of the Auditory Evoked Potential

    PubMed Central

    Lee, Kyung-Sang; Park, Young-Min

    2012-01-01

    Objective The loudness dependence of the auditory evoked potential (LDAEP) is suggested to be a marker of serotonin system function. This study explored the LDAEP of multiple mood statuses (depression, mania, and euthymia) and its clinical implication in bipolar disorder patients. Methods A total of 89 subjects, comprising 35 patients with bipolar disorder, 32 patients with schizophrenia, and 22 healthy controls were evaluated. The bipolar disorder cases comprised 10 depressed patients, 15 patients with mania, and 10 euthymic patients. The N1/P2 peak-to-peak amplitudes were measured at 5 stimulus intensities, and the LDAEP was calculated as the slope of the linear regression. Both cortical and source LDAEP values were calculated. Results LDAEP varied according to mood statuses, and was significantly stronger in cases of euthymia, depression, and mania. Cortical LDAEP was significantly stronger in patients with bipolar euthymia compared with schizophrenia, stronger in bipolar depression than in schizophrenia, stronger in healthy controls than in schizophrenia patients, and stronger in healthy controls than in patients with bipolar mania. Source LDAEP was significantly stronger in patients with bipolar euthymia, bipolar depression, and bipolar mania compared with schizophrenia, stronger in bipolar euthymia than in bipolar mania. Psychotic features weakened the source LDAEP relative to nonpsychotic features. The severity of the depressive symptom was negatively correlated with source LDAEP. Conclusion These findings suggest that the serotonin activity of patients with bipolar disorder may vary according to mood status. A longitudinal follow-up study should be pursued using drug-naive subjects. PMID:22993531

  14. Auditory evoked potentials to spectro-temporal modulation of complex tones in normal subjects and patients with severe brain injury.

    PubMed

    Jones, S J; Vaz Pato, M; Sprague, L; Stokes, M; Munday, R; Haque, N

    2000-05-01

    In order to assess higher auditory processing capabilities, long-latency auditory evoked potentials (AEPs) were recorded to synthesized musical instrument tones in 22 post-comatose patients with severe brain injury causing variably attenuated behavioural responsiveness. On the basis of normative studies, three different types of spectro-temporal modulation were employed. When a continuous 'clarinet' tone changes pitch once every few seconds, N1/P2 potentials are evoked at latencies of approximately 90 and 180 ms, respectively. Their distribution in the fronto-central region is consistent with generators in the supratemporal cortex of both hemispheres. When the pitch is modulated at a much faster rate ( approximately 16 changes/s), responses to each change are virtually abolished but potentials with similar distribution are still elicited by changing the timbre (e.g. 'clarinet' to 'oboe') every few seconds. These responses appear to represent the cortical processes concerned with spectral pattern analysis and the grouping of frequency components to form sound 'objects'. Following a period of 16/s oscillation between two pitches, a more anteriorly distributed negativity is evoked on resumption of a steady pitch. Various lines of evidence suggest that this is probably equivalent to the 'mismatch negativity' (MMN), reflecting a pre-perceptual, memory-based process for detection of change in spectro-temporal sound patterns. This method requires no off-line subtraction of AEPs evoked by the onset of a tone, and the MMN is produced rapidly and robustly with considerably larger amplitude (usually >5 microV) than that to discontinuous pure tones. In the brain-injured patients, the presence of AEPs to two or more complex tone stimuli (in the combined assessment of two authors who were 'blind' to the clinical and behavioural data) was significantly associated with the demonstrable possession of discriminative hearing (the ability to respond differentially to verbal commands

  15. Influence of detomidine and buprenorphine on motor-evoked potentials in horses.

    PubMed

    Nollet, H; Van Ham, L; Gasthuys, F; Dewulf, J; Vanderstraeten, G; Deprez, P

    2003-04-26

    Horses need to be sedated before they are investigated by transcranial magnetic stimulation because of the mild discomfort induced by the evoked muscle contraction and the noise of stimulation. This paper describes the influence of a combination of detomidine (10 microg/kg bodyweight) and a low dose of buprenorphine (2.4 microg/kg) on the onset latency and peak-to-peak amplitude of magnetic motor-evoked potentials in normal horses. There were no significant differences between measurements of these parameters made before the horses were sedated and measurements made 10 and 30 minutes after the drugs were administered. PMID:12739602

  16. Potential application of ocular and cervical vestibular-evoked myogenic potentials in Meniere's disease: a review.

    PubMed

    Young, Yi-Ho

    2013-02-01

    By stimulating the ear with air-conducted sound or bone-conducted vibration stimuli, vestibular-evoked myogenic potential (VEMP) can be recorded on the contracted neck muscles, termed cervical VEMP (cVEMP), and on the extraocular muscles, termed ocular VEMP (oVEMP). These two electrophysiological tests expand the test battery for clinicians to explore the dynamic otolithic function, adding a potential usefulness to the sacculocollic reflex and vestibulo-ocular reflex, respectively. The inner ear test battery, including audiometry, and cVEMP, oVEMP and caloric tests, is designed for complete evaluation of the inner ear function, namely, the cochlea, saccule, utricle, and semicircular canals, respectively. Using this test battery to study the localization and prevalence of hydrops formation reveals that the declining function in the cochlea, saccule, utricle, and semicircular canals mimics the declining sequence of hydrops formation in temporal bone studies. This study reviewed the physiological results in Meniere's patients via the inner ear test battery, especially the potential application of the oVEMP and cVEMP tests, to correlate with the histopathological findings of Meniere's disease. PMID:23070719

  17. A modified mirror projection visual evoked potential stimulator for presenting patterns in different orientations.

    PubMed

    Taylor, P K; Wynn-Williams, G M

    1986-07-01

    Modifications to a standard mirror projection visual evoked potential stimulator are described to enable projection of patterns in varying orientations. The galvanometer-mirror assembly is mounted on an arm which can be rotated through 90 degrees. This enables patterns in any orientation to be deflected perpendicular to their axes. PMID:2424725

  18. A Steady State Visually Evoked Potential Investigation of Memory and Ageing

    ERIC Educational Resources Information Center

    Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

    2009-01-01

    Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and…

  19. Cervical vestibular evoked myogenic potentials and caloric test results in individuals with auditory neuropathy spectrum disorders.

    PubMed

    Sujeet, Kumar Sinha; Niraj, Kumar Singh; Animesh, Barman; Rajeshwari, G; Sharanya, R

    2014-01-01

    Auditory neuropathy spectrum disorder is a type of hearing loss where outer hair cell function are normal (as evidenced by the preservation of OAEs and cochlear microphonics), whereas auditory nerve functions are abnormal (as evidenced by abnormal auditory brainstem evoked potentials beginning with wave I of the ABR) and acoustic reflexes to ipsilateral and contralateral tones are absent. It is likely that in cases with auditory neuropathy spectrum disorder not only the cochlear nerve, but also the vestibular nerves might get involved. The present study was conducted with an aim of finding out the inferior and superior vestibular nerve involvement through cervical vestibular evoked myogenic potentials and Caloric test results respectively in individuals with Auditory Neuropathy Spectrum Disorders. Total 26 participants who fulfilled the criteria of auditory neuropathy spectrum disorder participated for the study. Vestibular evoked myogenic potentials results showed absence of responses from most of the subjects also caloric responses showed bilateral hypofunctional responses in most of the participants, which is suggestive of involvement of both the inferior as well as superior vestibular nerve in individuals with auditory neuropathy spectrum disorders. Additionally there was no association between the pattern and degree of hearing loss to caloric test results and vestibular evoked myogenic potentials results findings. PMID:25095776

  20. PEAK N160 OF RAT FLASH EVOKED POTENTIAL: DOES IT REFLECT HABITUATION OR SENSITIZATION?

    EPA Science Inventory

    Flash evoked potentials recorded from awake rats contain a negative peak occurring about 160 msec after the flash (N160). This peak has been associated with a specific level of arousal, and/or habituation by various authors. The current studies attempted to determine whether chan...

  1. RAT FLASH EVOKED POTENTIAL PEAK N160 AMPLITUDE: MODULATION BY RELATIVE FLASH INTENSITY

    EPA Science Inventory

    The flash evoked potential (FEP) of rats has a large negative (N160) approximately 160 msec following stimulation. his peak has been reported to be modulated by the subject's state of behavioral arousal and influenced by several test parameters. hese experiments bind the influenc...

  2. Attentional Modulation of Visual-Evoked Potentials by Threat: Investigating the Effect of Evolutionary Relevance

    ERIC Educational Resources Information Center

    Brown, Christopher; El-Deredy, Wael; Blanchette, Isabelle

    2010-01-01

    In dot-probe tasks, threatening cues facilitate attention to targets and enhance the amplitude of the target P1 peak of the visual-evoked potential. While theories have suggested that evolutionarily relevant threats should obtain preferential neural processing, this has not been examined empirically. In this study we examined the effects of…

  3. TEMPERATURE-DEPENDENT CHANGES IN VISUAL EVOKED POTENTIALS OF RATS (JOURNAL VERSION)

    EPA Science Inventory

    The effects of alterations in body temperature on flash and pattern reversal evoked potential (FEPs and PREPs) were examined in hooded rats whose thermoregulatory capacity was compromised with lesions of the preoptic/anterior hypothalamic area and/or cold restraint. Body temperat...

  4. Intelligence and Complexity of the Averaged Evoked Potential: An Attentional Theory.

    ERIC Educational Resources Information Center

    Bates, Tim; And Others

    1995-01-01

    A study measuring average evoked potentials in 21 college students finds that intelligence test scores correlate significantly with the difference between string length in attended and nonattended conditions, a finding that suggests that previous inconsistencies in reporting string length-intelligence correlations may have resulted from confound…

  5. Negative Component of Visual Evoked Potential in Children with Cognitive Processing.

    ERIC Educational Resources Information Center

    Yanagihara, Masafumi; Sako, Akihito

    This study investigates a negative component (N220) of visual evoked potential (VEP) which increases as certain cognitive processes are activated. Nine experimental conditions were designed by combining three stimulus and three task conditions. Letters were used as verbal stimuli, matrix patterns were used as nonverbal stimuli, and white light was…

  6. WITHIN-SESSION CHANGES IN PEAK N160 AMPLITUDE OF FLASH EVOKED POTENTIALS IN RATS

    EPA Science Inventory

    The negative peak occurring approximately 160 msec after stimulation (peak N 160) flash evoked potentials (FEPS) of rats changes with repeated testing. abituation, sensitization, and arousal have all been invoked to explain these changes, but few studies have directly tested thes...

  7. STATIONARY PATTERN ADAPTATION AND THE EARLY COMPONENTS IN HUMAN VISUAL EVOKED POTENTIALS

    EPA Science Inventory

    Pattern-onset visual evoked potentials were elicited from humans by sinusoidal gratings of 0.5., 1, 2 and 4 cpd (cycles/degree) following adaptation to a blank field or one of the gratings. The wave forms recorded after blank field adaptation showed an early positive component, P...

  8. Influence of spiking activity on cortical local field potentials

    PubMed Central

    Waldert, Stephan; Lemon, Roger N; Kraskov, Alexander

    2013-01-01

    The intra-cortical local field potential (LFP) reflects a variety of electrophysiological processes including synaptic inputs to neurons and their spiking activity. It is still a common assumption that removing high frequencies, often above 300 Hz, is sufficient to exclude spiking activity from LFP activity prior to analysis. Conclusions based on such supposedly spike-free LFPs can result in false interpretations of neurophysiological processes and erroneous correlations between LFPs and behaviour or spiking activity. Such findings might simply arise from spike contamination rather than from genuine changes in synaptic input activity. Although the subject of recent studies, the extent of LFP contamination by spikes is unclear, and the fundamental problem remains. Using spikes recorded in the motor cortex of the awake monkey, we investigated how different factors, including spike amplitude, duration and firing rate, together with the noise statistic, can determine the extent to which spikes contaminate intra-cortical LFPs. We demonstrate that such contamination is realistic for LFPs with a frequency down to ∼10 Hz. For LFP activity below ∼10 Hz, such as movement-related potential, contamination is theoretically possible but unlikely in real situations. Importantly, LFP frequencies up to the (high-) gamma band can remain unaffected. This study shows that spike–LFP crosstalk in intra-cortical recordings should be assessed for each individual dataset to ensure that conclusions based on LFP analysis are valid. To this end, we introduce a method to detect and to visualise spike contamination, and provide a systematic guide to assess spike contamination of intra-cortical LFPs. PMID:23981719

  9. Auditory evoked potential P300 in adults: reference values

    PubMed Central

    Didoné, Dayane Domeneghini; Garcia, Michele Vargas; Oppitz, Sheila Jacques; da Silva, Thalisson Francisco Finamôr; dos Santos, Sinéia Neujahr; Bruno, Rúbia Soares; Filha, Valdete Alves Valentins dos Santos; Cóser, Pedro Luis

    2016-01-01

    ABSTRACT Objective To establish reference intervals for cognitive potential P300 latency using tone burst stimuli. Methods This study involved 28 participants aged between 18 and 59 years. P300 recordings were performed using a two-channel device (Masbe, Contronic). Electrode placement was as follows: Fpz (ground electrode), Cz (active electrode), M1 and M2 (reference electrodes). Intensity corresponded to 80 dB HL and frequent and rare stimulus frequencies to 1,000Hz and 2,000Hz, respectively. Stimuli were delivered binaurally. Results Mean age of participants was 35 years. Average P300 latency was 305ms. Conclusion Maximum acceptable P300 latency values of 362.5ms (305 + 2SD 28.75) were determined for adults aged 18 to 59 years using the protocol described. PMID:27462895

  10. Correlates of a single cortical action potential in the epidural EEG

    PubMed Central

    Teleńczuk, Bartosz; Baker, Stuart N; Kempter, Richard; Curio, Gabriel

    2015-01-01

    To identify the correlates of a single cortical action potential in surface EEG, we recorded simultaneously epidural EEG and single-unit activity in the primary somatosensory cortex of awake macaque monkeys. By averaging over EEG segments coincident with more than hundred thousand single spikes, we found short-lived (≈ 0.5 ms) triphasic EEG deflections dominated by high-frequency components > 800 Hz. The peak-to-peak amplitude of the grand-averaged spike correlate was 80 nV, which matched theoretical predictions, while single-neuron amplitudes ranged from 12 to 966 nV. Combining these estimates with post-stimulus-time histograms of single-unit responses to median-nerve stimulation allowed us to predict the shape of the evoked epidural EEG response and to estimate the number of contributing neurons. These findings establish spiking activity of cortical neurons as a primary building block of high-frequency epidural EEG, which thus can serve as a quantitative macroscopic marker of neuronal spikes. PMID:25554430

  11. Semi-automatic attenuation of cochlear implant artifacts for the evaluation of late auditory evoked potentials.

    PubMed

    Viola, Filipa Campos; De Vos, Maarten; Hine, Jemma; Sandmann, Pascale; Bleeck, Stefan; Eyles, Julie; Debener, Stefan

    2012-02-01

    Electrical artifacts caused by the cochlear implant (CI) contaminate electroencephalographic (EEG) recordings from implanted individuals and corrupt auditory evoked potentials (AEPs). Independent component analysis (ICA) is efficient in attenuating the electrical CI artifact and AEPs can be successfully reconstructed. However the manual selection of CI artifact related independent components (ICs) obtained with ICA is unsatisfactory, since it contains expert-choices and is time consuming. We developed a new procedure to evaluate temporal and topographical properties of ICs and semi-automatically select those components representing electrical CI artifact. The CI Artifact Correction (CIAC) algorithm was tested on EEG data from two different studies. The first consists of published datasets from 18 CI users listening to environmental sounds. Compared to the manual IC selection performed by an expert the sensitivity of CIAC was 91.7% and the specificity 92.3%. After CIAC-based attenuation of CI artifacts, a high correlation between age and N1-P2 peak-to-peak amplitude was observed in the AEPs, replicating previously reported findings and further confirming the algorithm's validity. In the second study AEPs in response to pure tone and white noise stimuli from 12 CI users that had also participated in the other study were evaluated. CI artifacts were attenuated based on the IC selection performed semi-automatically by CIAC and manually by one expert. Again, a correlation between N1 amplitude and age was found. Moreover, a high test-retest reliability for AEP N1 amplitudes and latencies suggested that CIAC-based attenuation reliably preserves plausible individual response characteristics. We conclude that CIAC enables the objective and efficient attenuation of the CI artifact in EEG recordings, as it provided a reasonable reconstruction of individual AEPs. The systematic pattern of individual differences in N1 amplitudes and latencies observed with different stimuli at

  12. ALTERATIONS IN RAT FLASH AND PATTERN REVERSAL EVOKED POTENTIALS AFTER ACUTE OR REPEATED ADMINISTRATION OF CARBON DISULFIDE (CS2)

    EPA Science Inventory

    Because solvents may selectively alter portions of visual evoked potentials, we examined the effects of carbon disulfide (CS2) on flash (FEPs) and pattern reversal (PREPs) evoked potentials. Long-Evans rats were administered (ip) carbon disulfide (CS2) either acutely or for 30 da...

  13. Sufentanil and nitrous oxide anaesthesia for the recording of transcranial magnetic motor evoked potentials in dogs.

    PubMed

    Van Ham, L M; Nijs, J; Mattheeuws, D R; Vanderstraeten, G G

    1996-06-29

    Transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle of the forelimbs and from the cranial tibial muscle of the hindlimbs of anaesthetised dogs. The dogs were premedicated with droperidol and fentanyl and a light plane of anaesthesia was induced and maintained with sufentanil and nitrous oxide. The potentials recorded under sufentanil and nitrous oxide anaesthesia were suppressed in comparison with baseline recordings under droperidol and fentanyl sedation: their latencies were significantly increased and their amplitudes significantly decreased (P < 0.05). However, the potentials could be recorded reliably in all the dogs and with very good reproducibility. This narcotic anaesthesia also allowed sensory evoked potentials to be recorded reliably. PMID:8817859

  14. 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. PMID:21728204

  15. Stimulus novelty, task relevance and the visual evoked potential in man

    NASA Technical Reports Server (NTRS)

    Courchesne, E.; Hillyard, S. A.; Galambos, R.

    1975-01-01

    The effect of task relevance on P3 (waveform of human evoked potential) waves and the methodologies used to deal with them are outlined. Visual evoked potentials (VEPs) were recorded from normal adult subjects performing in a visual discrimination task. Subjects counted the number of presentations of the numeral 4 which was interposed rarely and randomly within a sequence of tachistoscopically flashed background stimuli. Intrusive, task-irrelevant (not counted) stimuli were also interspersed rarely and randomly in the sequence of 2s; these stimuli were of two types: simples, which were easily recognizable, and novels, which were completely unrecognizable. It was found that the simples and the counted 4s evoked posteriorly distributed P3 waves while the irrelevant novels evoked large, frontally distributed P3 waves. These large, frontal P3 waves to novels were also found to be preceded by large N2 waves. These findings indicate that the P3 wave is not a unitary phenomenon but should be considered in terms of a family of waves, differing in their brain generators and in their psychological correlates.

  16. Modified variance ratio for objective detection of transient evoked potentials in bottlenose dolphins (Tursiops truncatus).

    PubMed

    Finneran, James J

    2008-12-01

    Evoked potential studies have often relied on one or more human observers to visually assess the averaged waveforms and decide if a response is present. Although simple and easy to implement, response detection strategies based on human observers are inherently subjective and depend on the observers' experience and biases. To avoid these shortcomings, some recent marine animal studies utilizing auditory steady-state responses have applied frequency-domain, statistically based objective detection methods; however, statistically based objective methods have not yet been applied to marine animal tests involving transient evoked responses, which are normally analyzed in the time domain. The present study applied a modified version of the variance ratio F(SP) to determine the presence or absence of evoked responses in two bottlenose dolphins (Tursiops truncatus) stimulated with tone pips. The appropriate degrees of freedom for the statistical tests were empirically determined in four dolphins. The modified variance ratio was found to be a useful tool and to provide an objective statistical approach for the detection of transient evoked potentials. PMID:19206829

  17. Cortical representation of spatiotemporal pattern of firing evoked by echolocation signals: population encoding of target features in real time.

    PubMed

    Palakal, M J; Wong, D

    1999-07-01

    Target perception in echolocating bats entails the generation of an acoustic image of the target in the auditory cortex. By integrating information conveyed in the sequence of acoustic echoes, the population of cortical neurons in hypothesized to encode different target features based on its spatiotemporal pattern of neural-spike firing during the course of echolocation. A biologically plausible approach to the cortical representation of target features is employed by using electrophysiological data recorded from the auditory cortex of the FM bat, Myotis lucifugus. A single-neuron model of delay-sensitive neurons is first approximated by the formulation of a Gaussian function with different variables to represent the delay-tuning properties of individual cortical neurons. A cortical region consisting of delay-sensitive neurons organized topographically according to best frequency (i.e., tontopically organized) is then modeled with multiple layers of the single-neuron model. A mechanism is developed to represent and encode the responses of these neurons based on time-dependent, incoming echo signals. The time-varying responses of the population of neurons are mapped spatially on the auditory-cortical surface as a cortical response map (CORMAP). The model is tested using phantom targets with single and multiple glints. These simulation results provide further validation of the current auditory framework as a biomimetic mechanism for capturing time-varying, acoustic stimuli impinging in the bat's ears, and the neural representation of acoustic stimulus features by saptiotemporal-firing patterns in the cortical population. PMID:10420638

  18. Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients.

    PubMed

    Mihalj, Mario; Lušić, Linda; Đogaš, Zoran

    2016-06-01

    It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P < 0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought. PMID:26749257

  19. Giant pseudoaneurysm originated from distal middle cerebral artery dissection treated by trapping under sensitive evoked potential and motor evoked potential monitoring: Case report and discussion

    PubMed Central

    Gripp, Daniel Andrade; Nakasone, Fábio Jundy; Maldaun, Marcos Vinícius Calfat; de Aguiar, Paulo Henrique Pires; Mathias, Luis Roberto

    2016-01-01

    Background: Dissecting giant pseudoaneurysm of the middle cerebral artery (MCA) is a rare lesion often presenting challenges to neurosurgical teams dealing with this specific pathology. Giant pseudoaneurysm originating from a dissecting distal segment of the MCA treated with aneurysm trapping under motor and sensitive evoked potential monitoring with a successful outcome is presented in the article followed by a brief discussion on the subject. Case Description: A case of a previously healthy young female patient admitted at the emergency room of Santa Paula Hospital with a history of a sudden headache and syncope, dysphasia, and Grade 4 right hemiparesis due to a large brain hemorrhage secondary to a 25 mm ruptured pseudoaneurysm originated from a distal left MCA dissecting segment is described. Because the patient risked neurological worsening, aneurysm was treated with parent and efferent vessel trapping technique and no changes on the sensitive and motor evoked potential (MEP) from baseline informed on this decision. Hemorrhage was completely drained after aneurysm was secured. Conclusion: Neurophysiological sensitive and MEP monitoring, on this specific case was a valuable tool and informed on the decision of trapping of this large vascular lesion. PMID:27127710

  20. [Prognostic evaluation of patients with severe head injury by motor evoked potentials induced by transcranial magnetic stimulation--combined analysis with brainstem auditory evoked potentials].

    PubMed

    Kaneko, M

    1995-05-01

    Prognostic evaluation of severe head injury was performed on the basis of transcranial magnetic motor evoked potentials (MEPs) and brainstem auditory evoked potentials (BAEPs). The subjects were 43 severe head injury patients with Glasgow Coma Scale Scores (GCS) of 9 or less. MEPs were recorded within 3 days after the injury. Patient outcome at 1, 6 and 12 months after the injury was correlated with the MEPs and BAEPs. Differences between MEP and BAEP findings in focal lesions and diffuse lesions also were analyzed. MEP wave latencies and inter-peak latencies between BAEP waves IV and V and between waves I and V were evaluated. There was a closer relationship between MEP latency and GOS, especially between the good recovery group and other outcome groups. At 1 month after the injury, there was a closer correlation between MEP latency and BAEP latency in those who died than in those who survived, and this tendency was more evident with regard to focal lesions. However, there was no significant correlation between MEP and patient outcome when the lesions were diffuse. There was no correlation between BAEP latencies and patient outcome, but there was a good, close correlation between prolonged MEP latency and unfavorable outcome at 1, 6, 12 months after injury. In conclusion, the combined use of BAEPs and MEPs induced by transcranial magnetic stimulation is useful in prognostic evaluation of acute head injury patients, especially when the brain lesions are focal. PMID:7786626

  1. Cocaine-induced vs. behaviour-related alterations of spontaneous and evoked discharge of somatosensory cortical neurons.

    PubMed

    Drouin, Candice; Waterhouse, Barry D

    2004-02-01

    While the abuse potential of cocaine stems mainly from its ability to increase dopaminergic transmission in limbic regions, drug actions on other monoamine-innervated circuits may contribute to the development and maintenance of cocaine addiction. Previous extracellular recordings in anaesthetized rats revealed a facilitatory influence of cocaine on primary sensory pathways, which could influence the processing of drug-related stimuli during the development of cocaine addiction. We further analysed these sensory effects of cocaine in freely behaving rats (n = 9). Using an array of eight microelectrodes chronically implanted in infragranular layers of primary somatosensory cortex, we recorded the basal activity of 40 single- and 64 multiunits and their response to electrical stimulation of the whisker pad before and after incremental doses of cocaine (0.25-2 mg/kg i.v.). Both spontaneous and cocaine-induced explorations were associated with elevated basal firing of the cortical neurons and suppression of their short-latency excitation and postexcitatory inhibition in response to the whisker-pad stimulation. In addition to exploration-related alterations, the administration of cocaine enhanced the long-latency rebound excitation induced by the whisker-pad stimulation. This component of the sensory response, which is more labile and does not seem to convey information about the physical characteristics of the stimulus, may participate in the processing of drug-related sensory stimuli. PMID:15009149

  2. Steady-State Somatosensory Evoked Potential for Brain-Computer Interface—Present and Future

    PubMed Central

    Ahn, Sangtae; Kim, Kiwoong; Jun, Sung Chan

    2016-01-01

    Brain-computer interface (BCI) performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials (SSVEPs) seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP) BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed. PMID:26834611

  3. 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. PMID:26233037

  4. 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.

  5. A lateralized auditory evoked potential elicited when auditory objects are defined by spatial motion.

    PubMed

    Butcher, Andrew; Govenlock, Stanley W; Tata, Matthew S

    2011-02-01

    Scene analysis involves the process of segmenting a field of overlapping objects from each other and from the background. It is a fundamental stage of perception in both vision and hearing. The auditory system encodes complex cues that allow listeners to find boundaries between sequential objects, even when no gap of silence exists between them. In this sense, object perception in hearing is similar to perceiving visual objects defined by isoluminant color, motion or binocular disparity. Motion is one such cue: when a moving sound abruptly disappears from one location and instantly reappears somewhere else, the listener perceives two sequential auditory objects. Smooth reversals of motion direction do not produce this segmentation. We investigated the brain electrical responses evoked by this spatial segmentation cue and compared them to the familiar auditory evoked potential elicited by sound onsets. Segmentation events evoke a pattern of negative and positive deflections that are unlike those evoked by onsets. We identified a negative component in the waveform - the Lateralized Object-Related Negativity - generated by the hemisphere contralateral to the side on which the new sound appears. The relationship between this component and similar components found in related paradigms is considered. PMID:21056097

  6. Comparison of electrically evoked whole-nerve action potential and electrically evoked auditory brainstem response thresholds in nucleus CI24R cochlear implant recipients.

    PubMed

    Hay-McCutcheon, Marcia J; Brown, Carolyn J; Clay, Kelly Schmidt; Seyle, Keely

    2002-09-01

    In this study, differences between electrically evoked whole-nerve action potential (EAP) and electrically evoked auditory brainstem response (EABR) measurements within Nucleus CI24R cochlear implant recipients were evaluated. Precurved modiolus-hugging internal electrode arrays, such as the CI24R, are designed to provide more direct stimulation of neural elements of the modiolus. If the electrode array is closer to the modiolus, electrically evoked and behavioral levels might be lower than were previously recorded for the straight electrode array, the CI24M. EAP and EABR growth functions and behavioral levels were obtained for 10 postlingually deafened adults. Results revealed no significant differences between EAP and EABR threshold levels, and these levels were not significantly lower than those obtained using the CI24M. PMID:12371659

  7. 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. PMID:27084224

  8. Regulation of Action Potential Waveforms by Axonal GABAA Receptors in Cortical Pyramidal Neurons

    PubMed Central

    Xia, Yang; Zhao, Yuan; Yang, Mingpo; Zeng, Shaoqun; Shu, Yousheng

    2014-01-01

    GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb) of the main axon trunk of layer –5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs) and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors. PMID:24971996

  9. Total i.v. anaesthesia for transcranial magnetic evoked potential spinal cord monitoring.

    PubMed

    Watt, J W; Fraser, M H; Soni, B M; Sett, P K; Clay, R

    1996-06-01

    Continuous intraoperative monitoring of transcranial magnetic motor evoked potentials (TcMMEP) can warn the surgeon of motor tract damage more effectively than somatosensory evoked potentials. As a non-invasive technique it is especially useful during post-traumatic internal fixation and is applicable whatever the level of the spinal cord at risk. Inhalation and many i.v. anaesthetics block the single pulse TcMMEP but a total i.v. anaesthetic regimen based on methohexitone, alfentanil and ketamine was effective in seven patients undergoing post-traumatic internal fixation. Consistent TcMMEP of 100-1000 mcV were obtained in all patients, with a latency change of only 2 ms above preoperative values. Good cardiovascular stability was maintained during operation. PMID:8679365

  10. 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

  11. Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties

    PubMed Central

    Casale, Amanda E.; Foust, Amanda J.; Bal, Thierry

    2015-01-01

    The role of interneurons in cortical microcircuits is strongly influenced by their passive and active electrical properties. Although different types of interneurons exhibit unique electrophysiological properties recorded at the soma, it is not yet clear whether these differences are also manifested in other neuronal compartments. To address this question, we have used voltage-sensitive dye to image the propagation of action potentials into the fine collaterals of axons and dendrites in two of the largest cortical interneuron subtypes in the mouse: fast-spiking interneurons, which are typically basket or chandelier neurons; and somatostatin containing interneurons, which are typically regular spiking Martinotti cells. We found that fast-spiking and somatostatin-expressing interneurons differed in their electrophysiological characteristics along their entire dendrosomatoaxonal extent. The action potentials generated in the somata and axons, including axon collaterals, of somatostatin-expressing interneurons are significantly broader than those generated in the same compartments of fast-spiking inhibitory interneurons. In addition, action potentials back-propagated into the dendrites of somatostatin-expressing interneurons much more readily than fast-spiking interneurons. Pharmacological investigations suggested that axonal action potential repolarization in both cell types depends critically upon Kv1 channels, whereas the axonal and somatic action potentials of somatostatin-expressing interneurons also depend on BK Ca2+-activated K+ channels. These results indicate that the two broad classes of interneurons studied here have expressly different subcellular physiological properties, allowing them to perform unique computational roles in cortical circuit operations. SIGNIFICANCE STATEMENT Neurons in the cerebral cortex are of two major types: excitatory and inhibitory. The proper balance of excitation and inhibition in the brain is critical for its operation. Neurons

  12. Evoked potential correlates of selective attention with multi-channel auditory inputs

    NASA Technical Reports Server (NTRS)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  13. Evaluation of transducers for obtaining intraoperative short-latency auditory evoked potentials.

    PubMed

    Erwin, C W; Gulevich, S J

    1985-08-01

    Operative monitoring of short-latency auditory evoked potentials during posterior fossa surgery requires audio transducers of small physical size so as to not interfere with the operative field. There are many relatively inexpensive transducers in the commercial audio hifi market of appropriate size. Some produce suitable biological responses and tolerate long term use without failure. The authors describe factors to consider and methods used in testing such transducers. PMID:2410230

  14. Influence of electrode site and size on variability of magnetic evoked potentials.

    PubMed

    Dunnewold, R J; van der Kamp, W; van den Brink, A M; Stijl, M; van Dijk, J G

    1998-12-01

    Successive magnetic evoked potentials (MEPs) concern varying motor neurons. We investigated whether this MEP-specific source of variability depends on electrode site and size. Amplitude variability (standard deviation) was largest over the center of the hypothenar muscles. Latencies were longer at distal and proximal sites than at the center site. Large electrodes (10 cm2) did not decrease this source of amplitude variability compared with EEG electrodes, in contrast to other sources of variability. PMID:9843083

  15. The syndrome of delayed posthemiplegic hemidystonia, hemiatrophy, and partial seizure: clinical, neuroimaging, and motor-evoked potential studies.

    PubMed

    Thajeb, P

    1996-08-01

    Magnetic motor-evoked potential (MEP) study of patients with the syndrome of delayed posthemiplegic hemidystonia, hemiatrophy, and partial or hemi-seizures ('4-hemi' syndrome) has not been described. Among 35 patients investigated for posthemiplegic movement disorders from February 1988 to January 1995, seven showed '4-hemi' syndrome. Clinical work-up, magnetic resonance images (MRI) and/or computed tomography (CT) were performed in all. Transcranial MEP studies were done in five patients. The remote causes of '4-hemi' syndrome were neonatal stroke, trauma, and encephalitis in infancy. The dystonia may occur as long as a decade after the initial insult. MRI or CT showed destructive lesion in the contralateral putamen (five patients), caudate (four), thalamus (five), and atrophy of the contralateral hemisphere (five). Other associations were porencephalic cyst. Wallerian degeneration, and asymmetric compensatory ventriculomegaly. MEP showed abnormalities in the affected upper limbs in four of five patients. The abnormalities were reduced amplitude of the compound muscle action potential following cortical stimulations with or without temporal dispersion, and with or without prolongation of its latency. The peripheral motor conductions following cervical stimulations were normal. MEP abnormalities may not be related to the hemiatrophy and the size of brain lesion per se. The hemidystonia is static after the second decade of life, and it is often difficult to treat. PMID:8884090

  16. An indirect component in the evoked compound action potential of the vagal nerve.

    PubMed

    Ordelman, Simone C M A; Kornet, Lilian; Cornelussen, Richard; Buschman, Hendrik P J; Veltink, Peter H

    2010-12-01

    The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the brain stem or coming via the neural network on the heart. In an experimental study of 15 pigs, we identified four components in the evoked compound action potentials. The fourth component was found to be an indirect component, which came from the periphery. The latency of the indirect component increased when heart rate and contractility were decreased by burst stimulation (P = 0.01; n = 7). When heart rate and contractility were increased by dobutamine administration, the latency of the indirect component decreased (P = 0.01; n = 9). This showed that the latency of the indirect component of the evoked compound action potentials may relate to the state of the cardiovascular system. PMID:20966537

  17. A portable device for recording evoked potentials, optimized for pattern ERG.

    PubMed

    McInturff, Stephen P; Buchser, William J

    2016-02-01

    Recording evoked potentials in un-anesthetized animals and people is a powerful technique to non-invasively measure the function of neurons. As such, the primary output neurons of the eye can be assessed by the pattern electroretinogram (PERG). Currently, electro-physiologic setups to perform PERG or related recordings are costly, complicated, and non-portable. Here, we design a simple steady-state PERG system, based off an Arduino board. The amplifier is built on a shield that fits over a microcontroller board, an Arduino, which digitizes the signal and sends it to a computer that presents stimuli then records and analyzes the evoked potentials. We used the device to record PERG accurately with a sensitivity as low as half a microvolt. The device has also been designed to implement other evoked potential recordings. This simple device can be quickly constructed and used for experiments in moving systems. Additionally, this device can be used to expose students in underserved areas to research technology that they would otherwise not have access to. PMID:26536572

  18. Nociceptive-Evoked Potentials Are Sensitive to Behaviorally Relevant Stimulus Displacements in Egocentric Coordinates.

    PubMed

    Moayedi, M; Di Stefano, G; Stubbs, M T; Djeugam, B; Liang, M; Iannetti, G D

    2016-01-01

    Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site. PMID:27419217

  19. Peak morphology and scalp topography of the pharyngeal sensory-evoked potential.

    PubMed

    Wheeler-Hegland, Karen; Pitts, Teresa; Davenport, Paul W

    2011-09-01

    The initiation of the pharyngeal stage of swallowing is dependent upon sensory input to the brainstem and cortex. The event-related evoked potential provides a measure of neuronal electrical activity as it relates to a specific stimulus. Air-puff stimulation to the posterior pharyngeal wall produces a sensory-evoked potential (PSEP) waveform. The goal of this study was to characterize the scalp topography and morphology for the component peaks of the PSEP waveform. Twenty-five healthy men and women served as research participants. PSEPs were measured via a 32-electrode cap (10-20 system) connected to SynAmps2 Neuroscan EEG System. Air puffs were delivered directly to the oropharynx using a thin polyethylene tube connected to a flexible laryngoscope. The PSEP waveform is characterized by four early- and mid-latency component peaks: an early positivity (P1) and negativity (N1), followed by a mid-latency positivity (P2) and negativity (N2). The early positive peak P1 is localized bilaterally to the lateral parietal scalp, the N1 medially in the frontoparietal region, and the P2 and N2 with diffuse scalp locations. Somatosensory and premotor regions are possible anatomical correlates of peak locations. Based on the latencies of the peaks, they are likely analogous to somatosensory- and respiratory-related evoked potential peaks. PMID:20890713

  20. Nociceptive-Evoked Potentials Are Sensitive to Behaviorally Relevant Stimulus Displacements in Egocentric Coordinates

    PubMed Central

    Di Stefano, G.; Stubbs, M. T.; Djeugam, B.; Liang, M.

    2016-01-01

    Abstract Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site. PMID:27419217

  1. Correlation of Transcranial Color Doppler to N20 Somatosensory Evoked Potential Detects Ischemic Penumbra in Subarachnoid Hemorrhage

    PubMed Central

    Di Pasquale, Piero; Zanatta, Paolo; Morghen, Ilaria; Bosco, Enrico; Forini, Elena

    2011-01-01

    Background: Normal subjects present interhemispheric symmetry of middle cerebral artery (MCA) mean flow velocity and N20 cortical somatosensory evoked potential (SSEP). Subarachnoid haemorrhage (SAH) can modify this pattern, since high regional brain vascular resistances increase blood flow velocity, and impaired regional brain perfusion reduces N20 amplitude. The aim of the study is to investigate the variability of MCA resistances and N20 amplitude between hemispheres in SAH. Methods: Measurements of MCA blood flow velocity (vMCA) by transcranial color-Doppler and median nerve SSEP were bilaterally performed in sixteen patients. MCA vascular changes on the compromised hemisphere were calculated as a ratio of the reciprocal of mean flow velocity (1/vMCA) to contralateral value and correlated to the simultaneous variations of interhemispheric ratio of N20 amplitude, within each subject. Data were analysed with respect to neuroimaging of MCA supplied areas. Results: Both interhemispheric ratios of 1/vMCA and N20 amplitude were detected >0.65 (p <0,01) in patients without neuroimages of injury. Both ratios became <0.65 (p <0.01) when patients showed unilateral images of ischemic penumbra and returned >0.65 if penumbra disappeared. The two ratios no longer correlated after structural lesion developed, as N20 detected in the damaged side remained pathological (ratio <0.65), whereas 1/vMCA reverted to symmetric interhemispheric state (ratio >0.65), suggesting a luxury perfusion. Conclusion: Variations of interhemispheric ratios of MCA resistance and cortical N20 amplitude correlate closely in SAH and allow identification of the reversible ischemic penumbra threshold, when both ratios become <0.65. The correlation is lost when structural damage develops. PMID:21660110

  2. Effect of propofol and remifentanil on a somatosensory evoked potential indicator of pain perception intensity in volunteers.

    PubMed

    Castro, Ana; Amorim, Pedro; Nunes, Catarina S; de Almeida, Fernando Gomes

    2015-10-01

    Somatosensory evoked potentials (SEPs) have been linked to noxious activation and stimulus intensity. In this exploratory study we investigated the impact of anaesthetic drugs on SEPs and pain ratings, to assess their applicability as an objective measure of the nociception/anti-nociception balance. Following institutional approval and written informed consent, 10 healthy adult volunteers were enrolled (29.5 ± 9.1 years, 63.0 ± 8.9 kg and 171.4 ± 7.2). Median nerve electrical stimulation was adjusted according to volunteers' sensitive, motor and painful thresholds (PT). Baseline SEPs were registered, and remifentanil and propofol administered using a stair scheme TCI. For each drug combination a 1.3×PT stimulus was administered, and volunteers evaluated pain intensity in a numerical rating scale (0-10). SEPs' amplitudes and latencies were normalized by the baseline values, reducing volunteers' intervariability. Stimulation currents varied between 6-52 mA (1.3×PT) and pain ratings between 0 and 9. Cortical SEPs latencies were decreased for higher stimulus intensities (P < 0.01), accompanied by increased pain ratings (P < 0.01). An individually adjusted/normalized ratio based on cortical SEPs amplitude and interpeak latency is proposed([Formula: see text]): [Formula: see text] and NSR were significantly correlated in three out of nine subjects, and [Formula: see text] and remifentanil Ce were significantly correlated in two (low number of evaluation points). [Formula: see text] was shown to decrease with increasing doses of propofol and remifentanil (P < 0.05). The proposed metric was depressed by anaesthetics and reflected pain evaluations. Further research is necessary to increase the number of volunteers and drugs' combination, to assess its applicability during surgically adequate anesthetic leves. PMID:25355557

  3. BODY TEMPERATURE-DEPENDENT AND INDEPENDENT ACTIONS OF CHLORDIMEFORM ON VISUAL EVOKED POTENTIALS AND AXONAL TRANSPORT IN OPTIC SYSTEM OF RAT

    EPA Science Inventory

    Pattern reversal evoked potentials (PREPs), flash evoked potentials (FEPs), optic nerve axonal transport, and body temperature were measured in hooded rats treated with either saline or the formamidine insecticide/acaricide, chlordimeform (CDM). Rats receiving CDM had low body te...

  4. Oscillatory brain states interact with late cognitive components of the somatosensory evoked potential.

    PubMed

    Reinacher, Matthias; Becker, Robert; Villringer, Arno; Ritter, Petra

    2009-09-30

    The question of interaction between ongoing neuronal activity and evoked responses has been addressed for different species, sensory systems and measurement modalities. Among other findings, there is converging evidence for an interaction of occipital alpha-rhythm amplitude with the visual evoked potential. Here, we test the hypothesis that the modulatory role of an ongoing rhythm might not be confined to the visual system and the occipital alpha rhythm, but instead may be generalized to other sensory systems. Using an online EEG analysis approach, we investigated the influence of the Rolandic alpha-rhythm on the somatosensory evoked potential (SEP). We triggered vibrotactile stimulation during periods of high Rolandic alpha-rhythm amplitude. Analysis revealed significant effects of pre-stimulus Rolandic alpha amplitude on the amplitude of the N140 and P260 components of the SEP, known to be linked to cognitive processing, but not on early sensory components. The N140-P260 complex shows a different focus in topography than the early sensory components and the pre-stimulus Rolandic alpha rhythm. These results indicate an involvement of Rolandic alpha-rhythm in higher cognitive processing. In more general terms--and in the context of similar studies in the visual system--our findings suggest that modulation of late EP components by ongoing rhythms might be a characteristic and possibly universal feature of sensory systems. PMID:19589356

  5. [The cervical somatosensory evoked potential and its relation to F-wave activity].

    PubMed

    Strenge, H

    1989-06-01

    In 6 healthy volunteers aged 18-25 years cervical somatosensory evoked potentials (CEPs) were recorded following stimulation of the right median nerve at the wrist. At the same time the antidromically elicited individual F-waves evoked by any single impulse were recorded from the abductor pollicis brevis muscle. By means of selective averaging of the neck responses it could be shown that there was a close relationship between an F-wave-activity of 120-150 microV/stimulus or more during the trial and the appearance or the enhancement of a negative peak occurring 0.5-1.4 ms after the main CEP component N13. An F-wave-activity of more than 224 microV/stimulus regularly resulted in a total change of the CEP configuration. PMID:2503360

  6. Stimulus novelty, task relevance and the visual evoked potential in man

    NASA Technical Reports Server (NTRS)

    Courchesne, E.; Hillyard, S. A.; Galambos, R.

    1975-01-01

    The visual evoked potential (VEP) to rare, task-relevant (counted) numerical stimuli was compared with VEPs to rare, task-irrelevant stimuli, both being randomly interspersed within a sequence of tachistoscopically-flashed background numbers. These task-irrelevant stimuli were of two classes: (1) easily recognizable (e.g., simple geometric shapes) and (2) completely novel (i.e., complex, colorful abstract-type drawings which were unrecognizable). It was found that such novel stimuli did, in fact, evoke large P3 waves, but they had different scalp distributions from those which followed the task-relevant stimuli. This indicates that at least two types of late positive P3 waves exist, differing both in brain source and psychological correlates.

  7. Temperature effects on evoked potentials of hippocampal slices from euthermic chipmunks, hamsters and rats

    NASA Technical Reports Server (NTRS)

    Hooper, D. C.; Martin, S. M.; Horowitz, J. M.

    1985-01-01

    1. Neural activity was recorded in hippocampal slices from euthermic chipmunks, hamsters and rats. 2. While recording the evoked potentials, the temperature of the Ringer's solution bathing the slice was varied by controlling the temperature of an outer chamber jacketing the recording chamber. 3. The temperature just below that at which a population spike could be evoked, Tt, was 10.4 +/- 0.3 degrees C (mean +/- SEM) for chipmunk slices, 14.1 +/- 0.4 degrees C for rat slices and 14.8 +/- 0.4 degrees C for hamster slices. Tt was significantly lower in the chipmunk slices (P<0.01) than in the rat and hamster slices. 4. Data were interpreted as consistent with the hypothesis that chipmunk hippocampal neurons are intrinsically cold resistant.

  8. Early and late stimulus-evoked cortical hemodynamic responses provide insight into the neurogenic nature of neurovascular coupling

    PubMed Central

    Kennerley, Aneurin J; Harris, Sam; Bruyns-Haylett, Michael; Boorman, Luke; Zheng, Ying; Jones, Myles; Berwick, Jason

    2012-01-01

    Understanding neurovascular coupling is a prerequisite for the interpretation of results obtained from modern neuroimaging techniques. This study investigated the hemodynamic and neural responses in rat somatosensory cortex elicited by 16 seconds electrical whisker stimuli. Hemodynamics were measured by optical imaging spectroscopy and neural activity by multichannel electrophysiology. Previous studies have suggested that the whisker-evoked hemodynamic response contains two mechanisms, a transient ‘backwards' dilation of the middle cerebral artery, followed by an increase in blood volume localized to the site of neural activity. To distinguish between the mechanisms responsible for these aspects of the response, we presented whisker stimuli during normocapnia (‘control'), and during a high level of hypercapnia. Hypercapnia was used to ‘predilate' arteries and thus possibly ‘inhibit' aspects of the response related to the ‘early' mechanism. Indeed, hemodynamic data suggested that the transient stimulus-evoked response was absent under hypercapnia. However, evoked neural responses were also altered during hypercapnia and convolution of the neural responses from both the normocapnic and hypercapnic conditions with a canonical impulse response function, suggested that neurovascular coupling was similar in both conditions. Although data did not clearly dissociate early and late vascular responses, they suggest that the neurovascular coupling relationship is neurogenic in origin. PMID:22126914

  9. The fMRI signal, slow cortical potential and consciousness

    PubMed Central

    He, Biyu J.; Raichle, Marcus E.

    2010-01-01

    As functional magnetic resonance imaging (fMRI) has become a driving force in cognitive neuroscience, it is crucial to understand the neural basis of the fMRI signal. Here, we discuss a novel neurophysiological correlate of the fMRI signal, the slow cortical potential (SCP), which also seems to modulate the power of higher-frequency activity, the more established neurophysiological correlate of the fMRI signal. We further propose a hypothesis for the involvement of the SCP in the emergence of consciousness, and review existing data that lend support to our proposal. This hypothesis, unlike several previous theories of consciousness, is firmly rooted in physiology and as such is entirely amenable to empirical testing. PMID:19535283

  10. The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia

    PubMed Central

    Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P.; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin

    2016-01-01

    Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia. PMID:26763954

  11. Sex-Specific Automatic Responses to Infant Cries: TMS Reveals Greater Excitability in Females than Males in Motor Evoked Potentials.

    PubMed

    Messina, Irene; Cattaneo, Luigi; Venuti, Paola; de Pisapia, Nicola; Serra, Mauro; Esposito, Gianluca; Rigo, Paola; Farneti, Alessandra; Bornstein, Marc H

    2015-01-01

    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

  12. 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

  13. Different Stimulation Frequencies Alter Synchronous Fluctuations in Motor Evoked Potential Amplitude of Intrinsic Hand Muscles—a TMS Study

    PubMed Central

    Sale, Martin V.; Rogasch, Nigel C.; Nordstrom, Michael A.

    2016-01-01

    The amplitude of motor-evoked potentials (MEPs) elicited with transcranial magnetic stimulation (TMS) varies from trial-to-trial. Synchronous oscillations in cortical neuronal excitability contribute to this variability, however it is not known how different frequencies of stimulation influence MEP variability, and whether these oscillations are rhythmic or aperiodic. We stimulated the motor cortex with TMS at different regular (i.e., rhythmic) rates, and compared this with pseudo-random (aperiodic) timing. In 18 subjects, TMS was applied at three regular frequencies (0.05 Hz, 0.2 Hz, 1 Hz) and one aperiodic frequency (mean 0.2 Hz). MEPs (n = 50) were recorded from three intrinsic hand muscles of the left hand with different functional and anatomical relations. MEP amplitude correlation was highest for the functionally related muscle pair, less for the anatomically related muscle pair and least for the functionally- and anatomically-unrelated muscle pair. MEP correlations were greatest with 1 Hz, and least for stimulation at 0.05 Hz. Corticospinal neuron synchrony is higher with shorter TMS intervals. Further, corticospinal neuron synchrony is similar irrespective of whether the stimulation is periodic or aperiodic. These findings suggest TMS frequency is a crucial consideration for studies using TMS to probe correlated activity between muscle pairs. PMID:27014031

  14. Pain Related Cortical Oscillations: Methodological Advances and Potential Applications

    PubMed Central

    Peng, Weiwei; Tang, Dandan

    2016-01-01

    Alongside the time-locked event-related potentials (ERPs), nociceptive somatosensory inputs can induce modulations of ongoing oscillations, appeared as event-related synchronization or desynchronization (ERS/ERD) in different frequency bands. These ERD/ERS activities are suggested to reflect various aspects of pain perception, including the representation, encoding, assessment, and integration of the nociceptive sensory inputs, as well as behavioral responses to pain, even the precise details of their roles remain unclear. Previous studies investigating the functional relevance of ERD/ERS activities in pain perception were normally done by assessing their latencies, frequencies, magnitudes, and scalp distributions, which would be then correlated with subjective pain perception or stimulus intensity. Nevertheless, these temporal, spectral, and spatial profiles of stimulus induced ERD/ERS could only partly reveal the dynamics of brain oscillatory activities. Indeed, additional parameters, including but not limited to, phase, neural generator, and cross frequency couplings, should be paid attention to comprehensively and systemically evaluate the dynamics of oscillatory activities associated with pain perception and behavior. This would be crucial in exploring the psychophysiological mechanisms of neural oscillation, and in understanding the neural functions of cortical oscillations involved in pain perception and behavior. Notably, some chronic pain (e.g., neurogenic pain and complex regional pain syndrome) patients are often associated with the occurrence of abnormal synchronized oscillatory brain activities, and selectively modulating cortical oscillatory activities has been showed to be a potential therapy strategy to relieve pain with the application of neurostimulation techniques, e.g., repeated transcranial magnetic stimulation (rTMS) and transcranial alternating current stimulation (tACS). Thus, the investigation of the oscillatory activities proceeding from

  15. Pain Related Cortical Oscillations: Methodological Advances and Potential Applications.

    PubMed

    Peng, Weiwei; Tang, Dandan

    2016-01-01

    Alongside the time-locked event-related potentials (ERPs), nociceptive somatosensory inputs can induce modulations of ongoing oscillations, appeared as event-related synchronization or desynchronization (ERS/ERD) in different frequency bands. These ERD/ERS activities are suggested to reflect various aspects of pain perception, including the representation, encoding, assessment, and integration of the nociceptive sensory inputs, as well as behavioral responses to pain, even the precise details of their roles remain unclear. Previous studies investigating the functional relevance of ERD/ERS activities in pain perception were normally done by assessing their latencies, frequencies, magnitudes, and scalp distributions, which would be then correlated with subjective pain perception or stimulus intensity. Nevertheless, these temporal, spectral, and spatial profiles of stimulus induced ERD/ERS could only partly reveal the dynamics of brain oscillatory activities. Indeed, additional parameters, including but not limited to, phase, neural generator, and cross frequency couplings, should be paid attention to comprehensively and systemically evaluate the dynamics of oscillatory activities associated with pain perception and behavior. This would be crucial in exploring the psychophysiological mechanisms of neural oscillation, and in understanding the neural functions of cortical oscillations involved in pain perception and behavior. Notably, some chronic pain (e.g., neurogenic pain and complex regional pain syndrome) patients are often associated with the occurrence of abnormal synchronized oscillatory brain activities, and selectively modulating cortical oscillatory activities has been showed to be a potential therapy strategy to relieve pain with the application of neurostimulation techniques, e.g., repeated transcranial magnetic stimulation (rTMS) and transcranial alternating current stimulation (tACS). Thus, the investigation of the oscillatory activities proceeding from

  16. MECHANISMS UNDERLYING SOMATOSENSORY CORTICAL DYNAMICS: II. IN VITRO STUDIES

    EPA Science Inventory

    The response of the sensorimotor cortical slice to repetitive, single site afferent drive is mapped using both evoked potential and metabolic mapping (2DG) methods. ystematic changes (increases or decreases) in the evoked potential occur during repetitive 3-5 Hz stimulation. hese...

  17. Brainstem auditory evoked potentials in children with low level cumulative lead exposure

    PubMed Central

    Alvarenga, Kátia F.; Morata, Thais C.; Lopes, Andréa Cintra; Feniman, Mariza Ribeiro; Corteletti, Lilian Cássia Bórnia Jacob

    2015-01-01

    Introduction Earlier studies have demonstrated an auditory effect of lead exposure in children,but information on the effects of low chronic exposures needs to be further elucidated. Objective To investigate the effect of low chronic exposures of the auditory system in childrenwith a history of low blood lead levels, using an auditory electrophysiological test. Methods Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6years, 8 months ± 3 years, 2 months). Results The mean time-integrated cumulative blood lead index was 12 g/dL (SD ± 5.7, range:2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I---III, III---V, and I---V, and the cumulative lead values. Conclusion No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area. PMID:25458254

  18. 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.

  19. Basic Principles and Recent Trends of Transcranial Motor Evoked Potentials in Intraoperative Neurophysiologic Monitoring

    PubMed Central

    TSUTSUI, Shunji; YAMADA, Hiroshi

    2016-01-01

    Transcranial motor evoked potentials (TcMEPs), which are muscle action potentials elicited by transcranial brain stimulation, have been the most popular method for the last decade to monitor the functional integrity of the motor system during surgery. It was originally difficult to record reliable and reproducible potentials under general anesthesia, especially when inhalation-based anesthetic agents that suppressed the firing of anterior horn neurons were used. Advances in anesthesia, including the introduction of intravenous anesthetic agents, and progress in stimulation techniques, including the use of pulse trains, improved the reliability and reproducibility of TcMEP responses. However, TcMEPs are much smaller in amplitude compared with compound muscle action potentials evoked by maximal peripheral nerve stimulation, and vary from one trial to another in clinical practice, suggesting that only a limited number of spinal motor neurons innervating the target muscle are excited in anesthetized patients. Therefore, reliable interpretation of the critical changes in TcMEPs remains difficult and controversial. Additionally, false negative cases have been occasionally encountered. Recently, several facilitative techniques using central or peripheral stimuli, preceding transcranial electrical stimulation, have been employed to achieve sufficient depolarization of motor neurons and augment TcMEP responses. These techniques might have potentials to improve the reliability of intraoperative motor pathway monitoring using TcMEPs. PMID:26935781

  20. Pheromone-evoked potentials and oscillations in the antennal lobes of the sphinx moth Manduca sexta.

    PubMed

    Heinbockel, T; Kloppenburg, P; Hildebrand, J G

    1998-06-01

    Using intra- and extracellular recording methods, we studied the activity of pheromone-responsive projection neurons in the antennal lobe of the moth Manduca sexta. Intracellularly recorded responses of neurons to antennal stimulation with the pheromone blend characteristically included both inhibitory and excitatory stages of various strengths. To observe the activity of larger groups of neurons, we recorded responses extracellularly in the macroglomerular complex of the antennal lobe. The macroglomerular complex is part of a specialized olfactory subsystem and the site of first-order central processing of sex-pheromonal information. Odors such as the pheromone blend and host-plant (tobacco) volatiles gave rise to evoked potentials that were reproducible upon repeated antennal stimulation. Evoked potentials showed overriding high-frequency oscillations when the antenna was stimulated with the pheromone blend or with either one of the two key pheromone components. The frequency of the oscillations was in the range of 30-50 Hz. Amplitude and frequency of the oscillations varied during the response to pheromonal stimulation. Recording intracellular and extracellular activity simultaneously revealed phase-locking of action potentials to potential oscillations. The results suggest that the activity of neurons of the macroglomerular complex was temporally synchronized, potentially to strengthen the pheromone signal and to improve olfactory perception. PMID:9631552

  1. Action of hallucinogens on raphe-evoked dorsal root potentials (DRPs) in the cat.

    PubMed

    Larson, A A; Anderson, E G

    1986-02-01

    The dorsal root potential (DRP) evoked by stimulation of the inferior central nucleus (ICN) of the cat is affected by administration of a variety of hallucinogenic agents. It has been previously shown that a single low dose of LSD is unique in that it potentiates this DRP, while injections of 5-methoxy-N,N- dimethyltryptamine (5-MeODMT), ketamine or phencyclidine (PCP) inhibit its production. Tolerance develops to the facilitatory effect of low doses of LSD on the DRP, but not to the inhibitory action of 5-MeODMT. Repeated injections of ketamine every 30 minutes also fail to produce tachyphylaxis to the inhibitory effect of this dissociative anesthetic. The raphe-evoked DRP is a long latency potential that is inhibited by a wide variety of putative serotonin antagonists and has therefore been traditionally thought to be mediated by serotonin. However, in light of the inability of either tryptophan or fluoxetine to potentiate this DRP, and the resistance of this DRP to blockade by parachlorophenylalanine, reserpine or intrathecally administered 5,7-dihydroxytryptamine, it appears that this potential may in fact be mediated, at least in part, by a non-serotonergic transmitter. PMID:3952125

  2. Direct comparison of two statistical methods for determination of evoked-potential thresholds

    NASA Astrophysics Data System (ADS)

    Langford, Ted L.; Patterson, James H., Jr.

    1994-07-01

    Several statistical procedures have been proposed as objective methods for determining evoked-potential thresholds. Data have been presented to support each of the methods, but there have not been direct comparisons using the same data. The goal of the present study was to evaluate correlation and variance ratio statistics using common data. A secondary goal was to evaluate the utility of a derived potential for determining thresholds. Chronic, bipolar electrodes were stereotaxically implanted in the inferior colliculi of six chinchillas. Evoked potentials were obtained at 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 kHz using 12-ms tone bursts and 12-ms tone bursts superimposed on 120-ms pedestal tones which were of the same frequency as the bursts, but lower in amplitude by 15 dB. Alternate responses were averaged in blocks of 200 to 4000 depending on the size of the response. Correlations were calculated for the pairs of averages. A response was deemed present if the correlation coefficient reached the 0.05 level of significance in 4000 or fewer averages. Threshold was defined as the mean of the level at which the correlation was significant and a level 5 dB below that at which it was not. Variance ratios were calculated as described by Elberling and Don (1984) using the same data. Averaged tone burst and tone burst-plus pedestal data were differenced and the resulting waveforms subjected to the same statistical analyses described above. All analyses yielded thresholds which were essentially the same as those obtained using behavioral methods. When the difference between stimulus durations is taken into account, however, evoked-potential methods produced lower thresholds than behavioral methods.

  3. Neuronal mechanisms mediating the variability of somatosensory evoked potentials during sleep oscillations in cats

    PubMed Central

    Rosanova, Mario; Timofeev, Igor

    2005-01-01

    The slow oscillation (SO) generated within the corticothalamic system is composed of active and silent states. The studies of response variability during active versus silent network states within thalamocortical system of human and animals provided inconsistent results. To investigate this inconsistency, we used electrophysiological recordings from the main structures of the somatosensory system in anaesthetized cats. Stimulation of the median nerve (MN) elicited cortical responses during all phases of SO. Cortical responses to stimulation of the medial lemniscus (ML) were virtually absent during silent periods. At the ventral-posterior lateral (VPL) level, ML stimuli elicited either EPSPs in isolation or EPSPs crowned by spikes, as a function of membrane potential. Response to MN stimuli elicited compound synaptic responses and spiked at any physiological level of membrane potential. The responses of dorsal column nuclei neurones to MN stimuli were of similar latency, but the latencies of antidromic responses to ML stimuli were variable. Thus, the variable conductance velocity of ascending prethalamic axons was the most likely cause of the barrages of synaptic events in VPL neurones mediating their firing at different level of the membrane potential. We conclude that the preserved ability of the somatosensory system to transmit the peripheral stimuli to the cerebral cortex during all the phases of sleep slow oscillation is based on the functional properties of the medial lemniscus and on the intrinsic properties of the thalamocortical cells. However the reduced firing ability of the cortical neurones during the silent state may contribute to impair sensory processing during sleep. PMID:15528249

  4. Changes in brainstem auditory evoked potentials among North Indian females with Type 2 diabetes mellitus

    PubMed Central

    Baweja, Pooja; Gupta, Sharat; Mittal, Shallu; Kumar, Avnish; Singh, Kamal Dev; Sharma, Raghuvansh

    2013-01-01

    Background: Diabetes mellitus is a complex metabolic disorder whose detrimental effects on various organ systems, including the nervous system are well known. Aim: This study was conducted to determine the changes in the brainstem auditory evoked potentials (BAEP) in patients with type 2 diabetes mellitus. Materials and Methods: In this case-control study, 116 females with type 2 diabetes and 100 age matched, healthy female volunteers were selected. The brainstem auditory evoked potentials (BAEP) were recorded with RMS EMG EP Marc-II Channel machine. The measures included latencies of waves I, II, III, IV, V and Interpeak latencies (IPL) I-III, III-V and I-V separately for both ears. Data was analysed statistically with SPSS software v13.0. Results: It was found that IPL I-III was significantly delayed (P = 0.028) only in the right ear, while the latency of wave V and IPL I-V showed a significant delay bilaterally (P values for right ear being 0.021 and 0.0381 respectively while those for left ear being 0.028 and 0.016 respectively), in diabetic females. However, no significant difference (P > 0.05) was found between diabetic and control subjects as regards to the latencies of waves I, II, III, IV and IPL III-V bilaterally and IPL I-III unilaterally in the left ear. Also, none of the BAEP latencies were significantly correlated with either the duration of disease or with fasting blood glucose levels in diabetics. Conclusions: Therefore, it could be concluded that diabetes patients have an early involvement of central auditory pathway, which can be detected quite accurately with the help of auditory evoked potential studies. PMID:24381878

  5. 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

  6. Pain perception and brain evoked potentials in patients with angina despite normal coronary angiograms.

    PubMed Central

    Frøbert, O.; Arendt-Nielsen, L.; Bak, P.; Funch-Jensen, P.; Peder Bagger, J.

    1996-01-01

    OBJECTIVE: To evaluate the role of nociception in patients with angina despite normal coronary angiograms and to investigate whether any abnormality is confined to visceral or somatosensory perception. METHODS: Perception, pain threshold, and brain evoked potentials to nociceptive electrical stimuli of the oesophageal mucosa and the sternal skin were investigated in 10 patients who had angina but normal coronary angiograms, no other signs of cardiac disease, and normal upper endoscopy. Controls were 10 healthy volunteers. The peaks of the evoked potential signal were designated N for negative deflections and P for positive. Numbers were given to the peaks in order of appearance after the stimulus. The peak to peak amplitudes (P1/N1, N1/P2) were measured in microV. RESULTS: (1) Angina pectoris was provoked in seven patients following continuous oesophageal stimulation. (2) Distant projection of pain occurred after continuous electrical stimulation of the oesophagus in four patients and in no controls. (3) Patients had higher oesophageal pain thresholds (median 16.3 mA v 7.3 mA, P = 0.02) to repeated stimuli than controls, whereas the values did not differ with respect to the skin. There were no intergroup differences in thresholds to single stimuli. (4) Patients had substantially reduced brain evoked potential amplitudes after both single oesophageal (P1/N1, median values: 7.2 microV, controls: 29.0 microV; N1/P2: 16.5 microV, controls: 66.0 microV; P < 0.001 for both) and skin (N1/P2: 13.5 microV; controls: 76.0 microV; P < 0.001) stimuli despite the similar pain thresholds. CONCLUSION: Central nervous system responses to visceral and somatosensory nociceptive input are altered in patients who have angina despite normal coronary angiograms. PMID:8665332

  7. Evoked Potential Monitoring Identifies Possible Neurological Injury During Positioning for Craniotomy

    PubMed Central

    Anastasian, Zirka H.; Ramnath, Brian; Komotar, Ricardo J.; Bruce, Jeffrey N.; Sisti, Michael B.; Gallo, Edward J.; Emerson, Ronald G.; Heyer, Eric J.

    2009-01-01

    Somatosensory evoked potential (SSEP) monitoring is commonly used to detect changes in nerve conduction and prevent impending nerve injury. We present a case series of 2 patients who had SSEP monitoring for their surgical craniotomy procedure, and who, upon positioning supine with their head tilted 30–45 degrees, developed unilateral upper extremity SSEP changes. These SSEP changes were reversed when the patients were repositioned. These cases indicate the clinical usefulness of monitoring SSEPs while positioning the patient and adjusting position accordingly to prevent injury. PMID:19690251

  8. Optical Coherence Tomography versus Visual Evoked Potentials in detecting subclinical visual impairment in multiple sclerosis

    PubMed Central

    Grecescu, M

    2014-01-01

    Rationale. Visual impairment is one of the most common clinical manifestations of multiple sclerosis (MS). Some multiple sclerosis patients complain of poor vision although the Snellen visual acuity is 20/20. This study reveals that sensitive measurements like visual evoked potential (VEP) and optical coherence tomography (OCT) can evidence subclinical disturbances of visual pathway. These methods examine the relation between the visual function (VEP) and retinal nerve fiber layer (RNFL) thickness, as a structural biomarker for axonal loss in patients with multiple sclerosis (MS). The findings in this study indicate the utility of combining structural and functional testing in clinical research on patients with MS. Purpose. To detect visual impairment in a population of visually asymptomatic patients affected by clinically definite multiple sclerosis (MS) and to compare the utility of optical coherence tomography (OCT) versus visual evoked potentials (VEP). Material and methods. Fourteen patients (28 eyes) affected by clinically definite MS, without a history of optic neuritis and asymptomatic for visual disturbances, were initially fully examined (visual acuity, ocular fundus, biomicroscopy) from an ophthalmic point of view and then measured by OCT (RNFL thickness) and VEP. Patients with a history of glaucoma or other retinal or optic nerve disease were excluded. Results. Of fourteen patients (28 eyes), VEP was abnormal in 11 cases (78,57%) and OCT (RNFL thickness) was abnormal in 5 cases (35,71%), while 3 patients had no abnormalities on neither tests. Conclusions. Optical coherence tomography (OCT) is less sensitive than visual evoked potentials (VEPs) in detecting visual subclinical impairment in patients with multiple sclerosis (MS). VEP remains the preferred test for the detection of clinical and subclinical optic neuritis. OCT may provide complementary information to VEP in cases with clinical definite MS and represent a valuable research instrument for the

  9. Underwater Anesthesia of Diamondback Terrapins (Malaclemys terrapin) for Measurement of Auditory Evoked Potentials

    PubMed Central

    Christiansen, Emily F; Piniak, Wendy E D; Lester, Lori A; Harms, Craig A

    2013-01-01

    Investigations into the biology of aquatic and semiaquatic species, including those involving sensory specialization, often require creative solutions to novel questions. We developed a technique for safely anesthetizing a semiaquatic chelonian species, the diamondback terrapin (Malaclemys terrapin), for measurement of auditory evoked potentials while animals were completely submerged in water. Custom-modified endotracheal tubes were used to obtain a watertight seal on both sides of the glottis and prevent aspiration of water during testing. No adverse effects were seen after the procedures, and assessment of venous blood-gas partial pressures and lactate concentrations indicated that sufficient gas exchange was maintained under anesthesia through manual ventilation. PMID:24351768

  10. Acoustically evoked potentials in two cephalopods inferred using the auditory brainstem response (ABR) approach.

    PubMed

    Hu, Marian Y; Yan, Hong Young; Chung, Wen-Sung; Shiao, Jen-Chieh; Hwang, Pung-Pung

    2009-07-01

    It is still a matter of debate whether cephalopods can detect sound frequencies above 400 Hz. So far there is no proof for the detection of underwater sound above 400 Hz via a physiological approach. The controversy of whether cephalopods have a sound detection ability above 400 Hz was tested using the auditory brainstem response (ABR) approach, which has been successfully applied in fish, crustaceans, amphibians, reptiles and birds. Using ABR we found that auditory evoked potentials can be obtained in the frequency range 400 to 1500 Hz (Sepiotheutis lessoniana) and 400 to 1000 Hz (Octopus vulgaris), respectively. The thresholds of S. lessoniana were generally lower than those of O. vulgaris. PMID:19275944

  11. Auditory Evoked Potential Audiograms Compared with Behavioral Audiograms in Aquatic Animals.

    PubMed

    Sisneros, Joseph A; Popper, Arthur N; Hawkins, Anthony D; Fay, Richard R

    2016-01-01

    Auditory evoked potentials (AEPs) have become popular for estimating hearing thresholds and audiograms. What is the utility of these measurements? How do AEP audiograms compare with behavioral audiograms? In general, AEP measurements for fishes and marine mammals often underestimate behavioral thresholds, but comparisons are especially complicated when the AEP and behavioral measures are obtained under different acoustic conditions. There is no single representative relationship between AEP and behavioral audiograms and these audiograms should not be considered equivalent. We suggest that the most valuable comparisons are those made by the same researcher using similar acoustic conditions for both measurements. PMID:26611067

  12. Auditory evoked potential: a proposal for further evaluation in children with learning disabilities

    PubMed Central

    Frizzo, Ana C. F.

    2015-01-01

    The information presented in this paper demonstrates the author’s experience in previews cross-sectional studies conducted in Brazil, in comparison with the current literature. Over the last 10 years, auditory evoked potential (AEP) has been used in children with learning disabilities. This method is critical to analyze the quality of the processing in time and indicates the specific neural demands and circuits of the sensorial and cognitive process in this clinical population. Some studies with children with dyslexia and learning disabilities were shown here to illustrate the use of AEP in this population. PMID:26113833

  13. Middle ear muscle contractions and their relation to pulse and echo evoked potentials in the bat

    NASA Technical Reports Server (NTRS)

    Henson, O. W., Jr.; Henson, M. M.

    1972-01-01

    An analysis is made of pulse and echo orientation cries of the Mustache Bat. That bat's cries are characterized by a long, 60 to 30 msec, pure tone component and brief beginning and terminal FM sweeps. In addition to obvious echo overlap and middle ear muscle contractions, the following are examined: (1) characteristics of pulse- and echo-evoked potential under various conditions, (2) evidence of changes in hearing sensitivity during and after pulse emission, and (3) the role of the middle ear muscles in bringing about these changes.

  14. Control of humanoid robot via motion-onset visual evoked potentials.

    PubMed

    Li, Wei; Li, Mengfan; Zhao, Jing

    2014-01-01

    This paper investigates controlling humanoid robot behavior via motion-onset specific N200 potentials. In this study, N200 potentials are induced by moving a blue bar through robot images intuitively representing robot behaviors to be controlled with mind. We present the individual impact of each subject on N200 potentials and discuss how to deal with individuality to obtain a high accuracy. The study results document the off-line average accuracy of 93% for hitting targets across over five subjects, so we use this major component of the motion-onset visual evoked potential (mVEP) to code people's mental activities and to perform two types of on-line operation tasks: navigating a humanoid robot in an office environment with an obstacle and picking-up an object. We discuss the factors that affect the on-line control success rate and the total time for completing an on-line operation task. PMID:25620918

  15. Control of humanoid robot via motion-onset visual evoked potentials

    PubMed Central

    Li, Wei; Li, Mengfan; Zhao, Jing

    2015-01-01

    This paper investigates controlling humanoid robot behavior via motion-onset specific N200 potentials. In this study, N200 potentials are induced by moving a blue bar through robot images intuitively representing robot behaviors to be controlled with mind. We present the individual impact of each subject on N200 potentials and discuss how to deal with individuality to obtain a high accuracy. The study results document the off-line average accuracy of 93% for hitting targets across over five subjects, so we use this major component of the motion-onset visual evoked potential (mVEP) to code people's mental activities and to perform two types of on-line operation tasks: navigating a humanoid robot in an office environment with an obstacle and picking-up an object. We discuss the factors that affect the on-line control success rate and the total time for completing an on-line operation task. PMID:25620918

  16. Monitoring of Motor and Somatosensory Evoked Potentials During Spine Surgery: Intraoperative Changes and Postoperative Outcomes

    PubMed Central

    2016-01-01

    Objective To evaluate whether the combination of muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials (SEPs) measured during spinal surgery can predict immediate and permanent postoperative motor deficits. Methods mMEP and SEP was monitored in patients undergoing spinal surgery between November 2012 and July 2014. mMEPs were elicited by a train of transcranial electrical stimulation over the motor cortex and recorded from the upper/lower limbs. SEPs were recorded by stimulating the tibial and median nerves. Results Combined mMEP/SEP recording was successfully achieved in 190 operations. In 117 of these, mMEPs and SEPs were stable and 73 showed significant changes. In 20 cases, motor deficits in the first 48 postoperative hours were observed and 6 patients manifested permanent neurological deficits. The two potentials were monitored in a number of spinal surgeries. For surgery on spinal deformities, the sensitivity and specificity of combined mMEP/SEP monitoring were 100% and 92.4%, respectively. In the case of spinal cord tumor surgeries, sensitivity was only 50% but SEP changes were observed preceding permanent motor deficits in some cases. Conclusion Intraoperative monitoring is a useful tool in spinal surgery. For spinal deformity surgery, combined mMEP/SEP monitoring showed high sensitivity and specificity; in spinal tumor surgery, only SEP changes predicted permanent motor deficits. Therefore, mMEP, SEP, and joint monitoring may all be appropriate and beneficial for the intraoperative monitoring of spinal surgery. PMID:27446784

  17. Cognitive evoked potentials to speech and tonal stimuli in children with implants.

    PubMed

    Kileny, P R; Boerst, A; Zwolan, T

    1997-09-01

    We investigated late and cognitive (mismatch negativity, P300) auditory potentials in 14 children with cochlear implants between the ages of 4 and 12 years. Length of cochlear implant use ranged from 7 to 84 months. Three types of stimulus contrasts were used: (1) a loudness contrast consisting of a 1500 Hz tone burst presented at 75 (standard) and 90 dB sound pressure level (deviant); (2) a frequency contrast consisting of a 1500 Hz tone burst (standard) and a 3000 Hz tone burst (deviant) presented at 80 dB sound pressure level; and (3) a speech contrast consisting of "heed" (standard) and "who'd" (deviant) delivered with a roving loudness paradigm involving a randomized variation of the levels of the standard and deviant stimuli. Latencies and amplitudes of components N1, P2, N2, and P3 and a mismatch negativity were measured. Overall, there were very few missing or unidentifiable components. P3 and mismatch negativity components were identified for all subjects and all stimuli. The latencies of most components were affected by stimulus type. There was a trend for longer latencies for the speech contrast compared with the loudness or frequency contrasts. This may be a reflection of the increased processing time required for the speech stimuli because of its higher complexity. There were several significant correlations between speech recognition and cognitive evoked potential latencies. These results indicate that the clinical use of cognitive evoked potentials in children with cochlear implants is feasible and informative. PMID:9334760

  18. Limitations in the rapid extraction of evoked potentials using parametric modeling.

    PubMed

    De Silva, A C; Sinclair, N C; Liley, D T J

    2012-05-01

    The rapid extraction of variations in evoked potentials (EPs) is of great clinical importance. Parametric modeling using autoregression with an exogenous input (ARX) and robust evoked potential estimator (REPE) are commonly used methods for extracting EPs over the conventional moving time average. However, a systematic study of the efficacy of these methods, using known synthetic EPs, has not been performed. Therefore, the current study evaluates the restrictions of these methods in the presence of known and systematic variations in EP component latency and signal-to-noise ratios (SNR). In the context of rapid extraction, variations of wave V of the auditory brainstem in response to stimulus intensity were considered. While the REPE methods were better able to recover the simulated model of the EP, morphology and the latency of the ARX-estimated EPs was a closer match to the actual EP than than that of the REPE-estimated EPs. We, therefore, concluded that ARX rapid extraction would perform better with regards to the rapid tracking of latency variations. By tracking simulated and empirically induced latency variations, we conclude that rapid EP extraction using ARX modeling is only capable of extracting latency variations of an EP in relatively high SNRs and, therefore, should be used with caution in low-noise environments. In particular, it is not a suitable method for the rapid extraction of early EP components such as the auditory brainstem potential. PMID:22394572

  19. The impact of synaptic conductance on action potential waveform: evoking realistic action potentials with a simulated synaptic conductance.

    PubMed

    Johnston, Jamie; Postlethwaite, Michael; Forsythe, Ian D

    2009-10-15

    Most current clamp studies trigger action potentials (APs) by step current injection through the recording electrode and assume that the resulting APs are essentially identical to those triggered by orthodromic synaptic inputs. However this assumption is not always valid, particularly when the synaptic conductance is of large magnitude and of close proximity to the axon initial segment. We addressed this question of similarity using the Calyx of Held/MNTB synapse; we compared APs evoked by long duration step current injections, short step current injections and orthodromic synaptic stimuli. Neither injected current protocol evoked APs that matched the evoked orthodromic AP waveform, showing differences in AP height, half-width and after-hyperpolarization. We postulated that this 'error' could arise from changes in the instantaneous conductance during the combined synaptic and AP waveforms, since the driving forces for the respective ionic currents are integrating and continually evolving over this time-course. We demonstrate that a simple Ohm's law manipulation of the EPSC waveform, which accounts for the evolving driving force on the synaptic conductance during the AP, produces waveforms that closely mimic those generated by physiological synaptic stimulation. This stimulation paradigm allows supra-threshold physiological stimulation (single stimuli or trains) without the variability caused by quantal fluctuation in transmitter release, and can be implemented without a specialised dynamic clamp system. Combined with pharmacological tools this method provides a reliable means to assess the physiological roles of postsynaptic ion channels without confounding affects from the presynaptic input. PMID:19560491

  20. Long-term potentiation and evoked spike responses in the cingulate cortex of freely mobile rats.

    PubMed

    Gorkin, A G; Reymann, K G; Aleksandrov, Yu I

    2003-10-01

    Long-term potentiation of synaptic efficiency is regarded as a major candidate for the role of the physiological mechanism of long-term memory. However, the limited development of concepts of the cellular and subcellular characteristics of the induction of long-term potentiation in animals in conditions of free behavior does not correspond to the importance of this question. The present study was undertaken to determine whether the characteristics of potentiation in the cingulate cortex in response to stimulation of fibers of the subiculo-cingulate tract are truly long-term, i.e., develop through all known phases and last at least 24 h, in freely moving animals. In addition, the study aims included identification of the effects of application of blockers of different types of glutamate receptors on the development of long-term potentiation and identification of the characteristics of spike responses of single cingulate cortex neurons to stimulation of the subiculo-cingulate tract. Long-term potentiation, lasting more than 24 h, was obtained in freely moving adult rats not treated with GABA blockers. Injection of glutamate NMDA synapse blockers led to significant decreases in evoked cingulate cortex potentials in response to test stimulation. Activatory short-latency spike responses were characterized by a low probability of spike generation, and this increased with increases in the stimulation current. These data demonstrated that it is methodologically possible to compare, in freely moving rats, the involvement of individual neurons in the mechanisms involved in learning one or another type of adaptive behavior and the dynamics of their evoked spike activity during the formation of long-term potentiation. PMID:14635990

  1. Visual evoked potentials to an illusory change in brightness: the Craik-Cornsweet-O'Brien effect.

    PubMed

    Suter, Steve; Crown, Nik

    2016-07-01

    Can brain electrical activity associated with the Craik-Cornsweet-O'Brien effect (CCOB) be identified in humans? Opposing luminance gradients met in the middle of a square image to create a luminance contrast-defined vertical border. The resulting rectangles on each side of the border were otherwise equiluminant, but appeared to differ in brightness, the CCOB effect. When the contrast gradients were swapped, the participants perceived darker and lighter rectangles trading places. This dynamic CCOB stimulus was reversed 1/s to elicit visual evoked potentials. The CCOB effect was absent in two control conditions. In one, the immediate contrast border, where the gradients met, was replaced by a dark vertical stripe; in the other, the outer segments of both rectangles, where the illusion would otherwise occur, were replaced by dark rectangles, leaving only the contrast-reversing gradients. Visual evoked potential components P1 and N2 were present for the CCOB stimuli, but not the control stimuli. Results are consistent with functional MRI and single unit evidence, suggesting that the brightness of the CCOB effect becomes dissociated from the luminance falling on the eye early in visual processing. These results favor explanations of brightness induction invoking rapid, early amplification of very low spatial-frequency information in the image to approximate natural scenes as opposed to a sluggish brightness adjustment spreading from the contrast border. PMID:27254394

  2. Combined Muscle Motor and Somatosensory Evoked Potentials for Intramedullary Spinal Cord Tumour Surgery

    PubMed Central

    Choi, Il; Hyun, Seung-Jae; Kang, Joong-Koo

    2014-01-01

    Purpose To evaluate whether intraoperative neurophysiologic monitoring (IONM) with combined muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials is useful for more aggressive and safe resection in intramedullary spinal cord tumour (IMSCT) surgery. Materials and Methods We reviewed data from consecutive patients who underwent surgery for IMSCT between 1998 and April 2012. The patients were divided into two groups based on whether or not IONM was applied. In the monitored group, the procedures were performed under IONM using 75% muscle amplitude decline weaning criteria. The control group was comprised of patients who underwent IMSCT surgery without IONM. The primary outcome was the rate of gross total excision of the tumour on magnetic resonance imaging at one week after surgery. The secondary outcome was the neurologic outcome based on the McCormick Grade scale. Results The two groups had similar demographics. The total gross removal tended to increase when intraoperative neurophysiologic monitoring was used, but this tendency did not reach statistical significance (76% versus 58%; univariate analysis, p=0.049; multivariate regression model, p=0.119). The serial McCormick scale score was similar between the two groups (based on repeated measure ANOVA). Conclusion Our study evaluated combined IONM of trans-cranial electrical (Tce)-mMEPs and SEPs for IMSCT. During IMSCT surgery, combined Tce-mMEPs and SEPs using 75% muscle amplitude weaning criteria did not result in significant improvement in the rate of gross total excision of the tumour or neurologic outcome. PMID:24954338

  3. Electromagnetic interference in intraoperative monitoring of motor evoked potentials and a wireless solution.

    PubMed

    Farajidavar, Aydin; Seifert, Jennifer L; Delgado, Mauricio R; Sparagana, Steven; Romero-Ortega, Mario I; Chiao, J-C

    2016-02-01

    Intraoperative neurophysiological monitoring (IONM) is utilized to minimize neurological morbidity during spine surgery. Transcranial motor evoked potentials (TcMEPs) are principal IONM signals in which the motor cortex of the subject is stimulated with electrical pulses and the evoked potentials are recorded from the muscles of interest. Currently available monitoring systems require the connection of 40-60 lengthy lead wires to the patient. These wires contribute to a crowded and cluttered surgical environment, and limit the maneuverability of the surgical team. In this work, it was demonstrated that the cumbersome wired system is vulnerable to electromagnetic interference (EMI) produced by operating room (OR) equipment. It was hypothesized that eliminating the lengthy recording wires can remove the EMI induced in the IONM signals. Hence, a wireless system to acquire TcMEPs was developed and validated through bench-top and animal experiments. Side-by-side TcMEPs acquisition from the wired and wireless systems in animal experiments under controlled conditions (absence of EMI from OR equipment) showed comparable magnitudes and waveforms, thus demonstrating the fidelity in the signal acquisition of the wireless solution. The robustness of the wireless system to minimize EMI was compared with a wired-system under identical conditions. Unlike the wired-system, the wireless system was not influenced by the electromagnetic waves from the C-Arm X-ray machine and temperature management system in the OR. PMID:26678325

  4. Defensiveness, anxiety and the amplitude/intensity function of auditory-evoked potentials.

    PubMed

    Kline, J P; Schwartz, G E; Fitzpatrick, D F; Hendricks, S E

    1993-07-01

    This study measured relationships between defensiveness, anxiety, and auditory-evoked potentials to tones of varied intensity. Subjects were designated as defensive if they scored > or = 7 on the L-scale of the Eysenck Personality Questionnaire, and high-anxious if they scored > or = 11 on the N-scale. Four groups resulted: 'high anxious', 'defensive high anxious', 'repressors' (i.e., defensive low anxious) and 'low anxious'. Evoked potentials were recorded from FZ, CZ, PZ, C3, C4, T3 and T4, referenced to linked ears in response to 74, 84, 94 and 104 dB SPL tones. High-defensive subjects showed lower P2 amplitudes to the 94 and 104 dB tones and lower amplitude/intensity slopes at FZ, CZ, C3 and C4. High-anxious subjects showed lower P2 amplitudes to all four stimulus intensities at FZ, CZ and PZ. The results are consistent with the hypothesis that defensiveness is associated with desensitization to intense or painful stimulation. PMID:8407437

  5. Visual evoked potentials to an illusory change in brightness: the Craik–Cornsweet–O’Brien effect

    PubMed Central

    Crown, Nik

    2016-01-01

    Can brain electrical activity associated with the Craik–Cornsweet–O’Brien effect (CCOB) be identified in humans? Opposing luminance gradients met in the middle of a square image to create a luminance contrast-defined vertical border. The resulting rectangles on each side of the border were otherwise equiluminant, but appeared to differ in brightness, the CCOB effect. When the contrast gradients were swapped, the participants perceived darker and lighter rectangles trading places. This dynamic CCOB stimulus was reversed 1/s to elicit visual evoked potentials. The CCOB effect was absent in two control conditions. In one, the immediate contrast border, where the gradients met, was replaced by a dark vertical stripe; in the other, the outer segments of both rectangles, where the illusion would otherwise occur, were replaced by dark rectangles, leaving only the contrast-reversing gradients. Visual evoked potential components P1 and N2 were present for the CCOB stimuli, but not the control stimuli. Results are consistent with functional MRI and single unit evidence, suggesting that the brightness of the CCOB effect becomes dissociated from the luminance falling on the eye early in visual processing. These results favor explanations of brightness induction invoking rapid, early amplification of very low spatial-frequency information in the image to approximate natural scenes as opposed to a sluggish brightness adjustment spreading from the contrast border. PMID:27254394

  6. Diagnostic use of dermatomal somatosensory-evoked potentials in spinal disorders: Case series

    PubMed Central

    Dikmen, Pinar Yalinay; Oge, A. Emre

    2013-01-01

    Objective/Context Dermatomal somatosensory-evoked potentials (dSEPs) may be valuable for diagnostic purposes in selected cases with spinal disorders. Design Reports on cases with successful use of dSEPs. Findings Cases 1 and 2 had lesions causing multiple root involvement (upper to middle lumbar region in Case 1 and lower sacral region in Case 2). Cystic lesions in both cases seemed to compress more than one nerve root, and stimulation at the center of the involved dermatomes in dSEPs helped to reveal the functional abnormality. Cases 3 and 4 had lesions involving the spinal cord with or without nerve root impairment. In Case 3, an magnetic resonance imaging (MRI)-verified lesion seemed to occupy a considerable volume of the lower spinal cord, causing only very restricted clinical sensory and motor signs. In Case 4, a cervical MRI showed a small well-circumscribed intramedullary lesion at right C2 level. All neurophysiological investigations were normal in the latter two patients (motor, tibial, and median somatosensory-evoked potentials in Case 3, and electromyography in both) except for the dSEPs. Conclusions Objectifying the presence and degree of sensory involvement in spinal disorders may be helpful for establishing diagnoses and in therapeutic decision-making. Valuable information could be provided by dSEPs in selected patients with multiple root or spinal cord involvement. PMID:24089995

  7. Evoked potentials elicited by natural stimuli in the brain of unanesthetized crayfish.

    PubMed

    Hernández-Falcón, J; Serrato, J; Ramón, F

    1999-05-01

    Experiments were conducted to test some characteristics of vision by crayfish underwater and in air, and determine possible motion reactions elicited in response to naturalistic or quasi-ethological visual stimuli. Chronically implanted electrodes on the brain were used to record visually evoked potentials in response to moving bars at different speeds or to fish of different sizes. Electroretinograms were also recorded to detect when an object or a shadow appeared in the crayfish visual field. Ongoing brain activity is mild under basal conditions, but increases in RMS by approximately 6% in response to bar passage and 12 to 53% in response to fish motionless or swimming in front of the crayfish. When crayfish are free to move, fish swimming in front of them elicit intense brain activity, together with displacement toward them and an attempt to grab them. Visual evoked potentials are elicited by moving objects as small as 1 degree at a distance of 30 cm in air as well as underwater. None of the stimuli used induced evident behavioral responses under our conditions. We conclude that vision-action activities can be divided into (a) vision of irrelevant objects with short lasting electrical activity and no motion in response to it; (b) vision of mildly interesting objects with long-lasting electrical effects, but no motion in response to it; and (c) vision of relevant objects with appropriate motion reaction. PMID:10357428

  8. Ground-truthing evoked potential measurements against behavioral conditioning in the goldfish, Carassius auratus

    NASA Astrophysics Data System (ADS)

    Hill, Randy J.; Mann, David A.

    2005-04-01

    Auditory evoked potentials (AEPs) have become commonly used to measure hearing thresholds in fish. However, it is uncertain how well AEP thresholds match behavioral hearing thresholds and what effect variability in electrode placement has on AEPs. In the first experiment, the effect of electrode placement on AEPs was determined by simultaneously recording AEPs from four locations on each of 12 goldfish, Carassius auratus. In the second experiment, the hearing sensitivity of 12 goldfish was measured using both classical conditioning and AEP's in the same setup. For behavioral conditioning, the fish were trained to reduce their respiration rate in response to a 5 s sound presentation paired with a brief shock. A modified staircase method was used in which 20 reversals were completed for each frequency, and threshold levels were determined by averaging the last 12 reversals. Once the behavioral audiogram was completed, the AEP measurements were made without moving the fish. The recording electrode was located subdermally over the medulla, and was inserted prior to classical conditioning to minimize handling of animal. The same sound stimuli (pulsed tones) were presented and the resultant evoked potentials were recorded for 1000-6000 averages. AEP input-output functions were then compared to the behavioral audiogram to compare techniques for estimating behavioral thresholds from AEP data.

  9. Omission evoked potentials (OEPs) in rats and the effects of diazepam.

    PubMed

    Jongsma, Marijtje L A; Coenen, Anton M L; Van Rijn, Clementina M

    2002-03-01

    We investigated whether evoked potentials to omitted stimuli could be measured in rats. Such an animal model would provide a measure of aspects of information processing concerned with expectancy and time estimation. In a first experiment, omission evoked potentials (OEPs) were elicited in rats by omitting stimuli (10%) from a train of tone pips with a fixed ISI (3 s). A control session consisted of omitting stimuli (10%) from a train of tone pips with a variable ISI (2.5-3.5 s). In a second experiment, OEPs were measured in rats that received 4 mg x kg(-1) diazepam or vehicle sc. In the first experiment, half of the animals showed OEPs that consisted of a late-latency positive wave, the other rats showed a slow negative drift. No OEPs were found in the control session. Rats showing OEPs consisting of a positive wave in Experiment 1 were passed to Experiment 2. In the vehicle condition of the second experiment, all rats showed OEPs. In the diazepam condition no OEPs were found. We found that OEPs can be measured in rats. In addition, OEPs are disrupted by diazepam. We propose that OEPs provide an elegant tool to elicit selectively endogenous EP components. PMID:12212673

  10. Color vision in attention-deficit/hyperactivity disorder: A pilot visual evoked potential study

    PubMed Central

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary

    2014-01-01

    Background Individuals with attention-deficit/hyperactivity disorder (ADHD) are reported to manifest visual problems (including ophthalmological and color perception, particularly for blue–yellow stimuli), but findings are inconsistent. Accordingly, this study investigated visual function and color perception in adolescents with ADHD using color Visual Evoked Potentials (cVEP), which provides an objective measure of color perception. Method Thirty-one adolescents (aged 13–18), 16 with a confirmed diagnosis of ADHD, and 15 healthy peers, matched for age, gender, and IQ participated in the study. All underwent an ophthalmological exam, as well as electrophysiological testing color Visual Evoked Potentials (cVEP), which measured the latency and amplitude of the neural P1 response to chromatic (blue–yellow, red–green) and achromatic stimuli. Result No intergroup differences were found in the ophthalmological exam. However, significantly larger P1 amplitude was found for blue and yellow stimuli, but not red/green or achromatic stimuli, in the ADHD group (particularly in the medicated group) compared to controls. Conclusion Larger amplitude in the P1 component for blue–yellow in the ADHD group compared to controls may account for the lack of difference in color perception tasks. We speculate that the larger amplitude for blue–yellow stimuli in early sensory processing (P1) might reflect a compensatory strategy for underlying problems including compromised retinal input of s-cones due to hypo-dopaminergic tone. PMID:25435188

  11. Auditory evoked potential (AEP) measurements in stranded rough-toothed dolphins (Steno bredanensis)

    NASA Astrophysics Data System (ADS)

    Cook, Mandy L. H.; Manire, Charles A.; Mann, David A.

    2005-04-01

    Thirty-six rough-toothed dolphins (Steno bredanensis) live-stranded on Hutchinson Island, FL on August 6, 2004. Seven animals were transported to Mote Marine Laboratory for rehabilitation. Two auditory evoked potential (AEP) measurements were performed on each of five of these dolphins in air using a jawphone to present acoustic stimuli. Modulation rate transfer functions (MRTFs) were measured to establish how well the auditory system follows the temporal envelope of acoustic stimuli. A 40 kHz stimulus carrier was amplitude modulated (AM) with varying rates ranging from 200 Hz to 1800 Hz, in 200 Hz steps. The best AM-rate from the first dolphin tested was 1500 Hz. This AM rate was used in subsequent AEP measurements to determine evoked-potential hearing thresholds between 5000 and 80000 Hz. These findings show that rough-toothed dolphins can detect sounds between 5 and 80 kHz, and are most likely capable of detecting frequencies much higher than 80 kHz. MRTF data suggest that rough-toothed dolphins have a high temporal resolution, similar to that of other cetaceans.

  12. Brainstem auditory and somatosensory evoked potentials: a methodological study to evaluate the reproducibility of two devices.

    PubMed

    Moncho, D; Poca, M A; Minoves, T; Ferré, A; Rahnama, K; Sahuquillo, J

    2014-12-01

    We aimed to determine whether statistical significant differences exist between the sets of results obtained from two devices used in our department for measuring brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs). We obtained BAEP and median and posterior tibial nerve SEP values bilaterally in ten healthy subjects. The tests were performed on the same subject using two devices consecutively. The equipment consisted of a Nicolet Viking-IV (Nicolet, Madison, WI, USA) and a Viking Select (Viasys Healthcare, Madison, WI, USA), and the same recording electrodes and stimulator (auditory and electrical) were used without modifying any postural position of the subject. The stimuli and recording parameters were the same for both devices. We obtained 20 sets of data for each type of test. The Bland–Altman plots as well as the one-sample t-test or Wilcoxon signed rank test were used to compare data between the two groups of data sets. We found no significant differences between the sets of values obtained with the two devices. Our analysis indicates that the two devices are equal in recording all different variables of BAEP and SEP, which allows us to combine the BAEP and SEP data obtained from the two devices for follow-up studies involving quantitative statistical methods. This study received institutional approval (protocol number PRAG-154/2013). PMID:25420133

  13. Painful stimuli evoke potentials recorded from the medial temporal lobe in humans

    PubMed Central

    Liu, C.C.; Ohara, S.; Franaszczuk, P.; Zagzoog, N.; Gallagher, M.; Lenz, F.A.

    2009-01-01

    The role of human medial temporal structures in fear conditioning has led to the suggestion that neurons in these structures might respond to painful stimuli. We have now tested the hypothesis that recordings from these structures will demonstrate potentials related to the selective activation of cutaneous nociceptors by a painful laser stimulus (laser evoked potential, LEP)(Kenton et al., 1980). Recordings were carried out through electrodes implanted bilaterally in these structures for the investigation of intractable epilepsy. Reproducible LEPs were commonly recorded both bilaterally and unilaterally, while LEPs were recorded at contacts on the left (9/14, P=0.257) as commonly as on the right (5/14), independent of the hand stimulated. Along electrodes traversing the amygdala the majority of LEPs were recorded from dorsal contacts near the central nucleus of the amygdala and the nucleus basalis. Stimulus evoked changes in theta activity were observed at contacts on the right at which isolated early negative LEPs (N2*) responses could be recorded. Contacts at which LEPs could be recorded were as commonly located in medial temporal structures with evidence of seizure activity as on those without. These results demonstrate the presence of pain-related inputs to the medial temporal lobe where they may be involved in associative learning to produce anxiety and disability related to painful stimuli. PMID:19925853

  14. Auditory and somatosensory evoked potentials in a case of "locked-in" syndrome: a clinical and pathological study.

    PubMed

    Soria, E; Fine, E; Hajdu, I

    1989-01-01

    Brainstem auditory evoked potentials were bilaterally normal, and somatosensory evoked potentials were unilaterally abnormal in a patient with a large pontine infarct causing a "locked-in" syndrome. In the post mortem examination, the lesion extended unilaterally into the pontine tegmentum, partially involving the left medial lemniscus. The P14 potential was absent and the N20 potential was diminished in amplitude with right median nerve stimulation. The origin of the P14 potential has been debated in the literature. This case provides evidence for the P14 generator being located at the pontine level, in relation to a lemniscal area above the decussation of the somatosensory pathway. Evoked potentials can help to determine the tegmental extension of the pontine infarcts in the "locked-in" syndrome, especially in patients unable to cooperate with clinical examination. PMID:2666101

  15. Sensorimotor and cognitive involvement of the beta-gamma oscillation in the frontal N30 component of somatosensory evoked potentials.

    PubMed

    Cebolla, A M; Cheron, G

    2015-12-01

    The most consistent negative cortical component of somatosensory evoked potentials (SEPs), namely the frontal N30, can be considered more multidimensional than a strict item of standard somatosensory investigation, dedicated to tracking the afferent volley from the peripheral sensory nerve potentials to the primary somatosensory cortex. In this review, we revisited its classical sensorimotor implication within the framework of the recent oscillatory model of ongoing electroencephalogram (EEG) rhythms. Recently, the N30 component was demonstrated to be related to an increase in the power of beta-gamma EEG oscillation and a phase reorganization of the ongoing EEG oscillations (phase locking) in this frequency band. Thanks to high density EEG recordings and the inverse modeling method (swLORETA), it was shown that different overlapping areas of the motor and premotor cortex are specifically involved in generating the N30 in the form of a beta gamma oscillatory phase locking and power increase. This oscillatory approach has allowed a re-investigation of the movement gating behavior of the N30. It was demonstrated that the concomitant execution of finger movements by a stimulated hand impinges the temporal concentration of the ongoing beta/gamma EEG oscillations and abolished the N30 component. It was hypothesized that the involvement of neuronal populations in both the sensorimotor cortex and other related areas were unable to respond to the phasic sensory activation so could not phase-lock their oscillatory signals to the external sensory input during the movement. In this case, the actual movement has primacy over the artificial somatosensory input. The contribution of the ongoing oscillatory activity in the N30 emergence calls for a reappraisal of fundamental and clinical interpretations of the frontal N30 component. An absent or reduced amplitude of the N30 can now be viewed not only as a deficit in the activation of the somatosensory synaptic network in response

  16. Electromotive Triggering and Single Sweep Analysis of Vestibular Evoked Myogenic Potentials (VEMPs).

    PubMed

    Hecker, Dietmar J; Lohscheller, Joerg; Schorn, Bianca; Koch, Klaus Peter; Schick, Bernhard; Dlugaiczyk, Julia

    2014-01-01

    Cervical (c) and ocular (o) vestibular evoked myogenic potentials (VEMPs) provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice. First, recording of oVEMPs is compromised by small n10 amplitudes. Second, VEMP analysis is currently based on the averaging technique, resulting in a loss of information compared to single sweep analysis. Here, we: 1) developed a novel electromotive trigger mechanism for evoking VEMPs by bone-conducted vibration to the forehead and 2) established maximum entropy extraction of complex wavelet transforms for calculation of phase synchronization between VEMP single sweeps. Both c- and oVEMPs were recorded for n=10 healthy individuals. The oVEMP n10 amplitude was consistently higher (right: 24.84±9.71 μV; left: 27.40±14.55 μV) than previously described. Stable VEMP signals were reached after a smaller number of head taps (oVEMPs 6; cVEMPs 11) compared to current recommendations. Phase synchronization vectors and phase shift values were successfully determined for simulated and clinically recorded VEMPs, providing information about the impact of noise and phase jitter on the VEMP signal. Thus, the proposed method constitutes an easy-to-use approach for the fast detection and analysis of VEMPs in clinical practice. PMID:23529108

  17. A portable system for marine mammal auditory-evoked potential measurements

    NASA Astrophysics Data System (ADS)

    Finneran, James J.; Houser, Dorian S.

    2001-05-01

    Limitations to behavioral measures of hearing sensitivity in marine mammals include the time and expense typically required to train subjects. These limitations have resulted in limited subjects and lingering questions regarding intraspecific variability. An alternative to behavioral methods is the electrophysiological method, where passive electrodes are used to measure auditory-evoked potentials (AEPs) generated by the brain in response to sound stimuli. Marine mammal AEP measurements have been limited by the complexity of the technique and the limited applicability of commercially available AEP systems. In this paper, a portable, laptop computer-based system for marine mammal AEP measurements will be presented. The system features commercial off-the-shelf components, including a data acquisition PC card, biopotential amplifier, and programmable attenuator. The system is housed in a rugged, shock-resistant case. Custom software is used to present sound stimuli, record evoked responses, and analyze the resulting data. The system has been used to measure auditory brainstem responses to clicks and tone pips and envelope following responses to amplitude-modulated tones in bottlenose dolphins. Preliminary data obtained with the system will be presented and compared to behavioral hearing measures. [Work supported by the ILIR at SPAWARSYSCEN-SD and the ONR.

  18. A brain computer interface using motion-onset visual evoked potential

    NASA Astrophysics Data System (ADS)

    Guo, Fei; Hong, Bo; Gao, Xiaorong; Gao, Shangkai

    2008-12-01

    This paper presents a novel brain-computer interface (BCI) based on motion-onset visual evoked potentials (mVEPs). mVEP has never been used in BCI research, but has been widely studied in basic research. For the BCI application, the brief motion of objects embedded into onscreen virtual buttons is used to evoke mVEP that is time locked to the onset of motion. EEG data registered from 15 subjects are used to investigate the spatio-temporal pattern of mVEP in this paradigm. N2 and P2 components, with distinct temporo-occipital and parietal topography, respectively, are selected as the salient features of the brain response to the attended target that the subject selects by gazing at it. The computer determines the attended target by finding which button elicited prominent N2/P2 components. Besides a simple feature extraction of N2/P2 area calculation, the stepwise linear discriminant analysis is adopted to assess the target detection accuracy of a five-class BCI. A mean accuracy of 98% is achieved when ten trials data are averaged. Even with only three trials, the accuracy remains above 90%, suggesting that the proposed mVEP-based BCI could achieve a high information transfer rate in online implementation.

  19. Cortical localization of cognitive function by regression of performance on event-related potentials

    NASA Technical Reports Server (NTRS)

    Montgomery, R. W.; Montgomery, L. D.; Guisado, R.

    1992-01-01

    This paper demonstrates a new method of mapping cortical localization of cognitive function, using electroencephalographic data. Cross-subject regression analyses are used to identify cortical sites and post-stimulus latencies where there is a high correlation between subjects' performance and their cognitive event-related potential amplitude. The procedure was tested using a mental arithmetic task and was found to identify essentially the same cortical regions that have been associated with such tasks on the basis of research with patients suffering localized cortical lesions. Thus, it appears to offer an inexpensive, noninvasive tool for exploring the dynamics of localization in neurologically normal subjects.

  20. Effect of galvanic vestibular stimulation on movement-related cortical potential.

    PubMed

    Lee, Jeong-Woo

    2015-06-01

    [Purpose] This study examined the effects of galvanic vestibular stimulation on motion-related cortical potential. [Subjects and Methods] Fourty healthy female adult subjects each received galvanic vestibular stimulation or sham treatment. For galvanic vestibular stimulation, the anode and cathode were applied to the right and left mastoid processes, respectively, for 10 minutes. Motion-related cortical potential was tested pre- and post-treatment. To measure motion-related cortical potential, surface electromyography signals were generated by 50 thumb abductions with electrode application on the abductor pollicis brevis of the left (i.e., non-dominant) hand. [Results] The negative slope cortical potential on the C3 area (i.e., dominant hand) and cortical negative slope and motor potential on the C4 area (i.e., non-dominant hand) showed significant interaction effects. The galvanic vestibular stimulation group showed an increased negative slope amplitude in the C3 area, and increased negative slope and motor potential amplitudes in the C4 area compared to the sham group. [Conclusion] Galvanic vestibular stimulation increases the negative slope and motor potential amplitudes of the homonymous brain cortex area, which controls hand function and motion-related cortical potential, and the negative slope amplitude of the opposite cortical area, thus activating the brain areas for hand function. PMID:26180369

  1. Effect of galvanic vestibular stimulation on movement-related cortical potential

    PubMed Central

    Lee, Jeong-Woo

    2015-01-01

    [Purpose] This study examined the effects of galvanic vestibular stimulation on motion-related cortical potential. [Subjects and Methods] Fourty healthy female adult subjects each received galvanic vestibular stimulation or sham treatment. For galvanic vestibular stimulation, the anode and cathode were applied to the right and left mastoid processes, respectively, for 10 minutes. Motion-related cortical potential was tested pre- and post-treatment. To measure motion-related cortical potential, surface electromyography signals were generated by 50 thumb abductions with electrode application on the abductor pollicis brevis of the left (i.e., non-dominant) hand. [Results] The negative slope cortical potential on the C3 area (i.e., dominant hand) and cortical negative slope and motor potential on the C4 area (i.e., non-dominant hand) showed significant interaction effects. The galvanic vestibular stimulation group showed an increased negative slope amplitude in the C3 area, and increased negative slope and motor potential amplitudes in the C4 area compared to the sham group. [Conclusion] Galvanic vestibular stimulation increases the negative slope and motor potential amplitudes of the homonymous brain cortex area, which controls hand function and motion-related cortical potential, and the negative slope amplitude of the opposite cortical area, thus activating the brain areas for hand function. PMID:26180369

  2. Interactions Between Dyspnea and the Brain Processing of Nociceptive Stimuli: Experimental Air Hunger Attenuates Laser-Evoked Brain Potentials in Humans

    PubMed Central

    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. PMID:26648875

  3. Neural Consequences of Increasing Body Weight: Evidence from Somatosensory Evoked Potentials and the Frequency-Specificity of Brain Oscillations

    PubMed Central

    Lhomond, Olivia; Teasdale, Normand; Simoneau, Martin; Mouchnino, Laurence

    2016-01-01

    Previous studies on the control of human balance suggested that increased pressure under the feet, leading to reduced plantar sole mechanoreceptors sensitivity, increases body sway. Although this suggestion is attracting, it is unclear whether increased plantar sole pressure simply reduces the transmission of plantar sole afferent to the cortex or also alters the sensorimotor integrative mechanisms. Here we used electrical stimulation applied under the sole of the foot to probe the sensorimotor mechanisms processing foot mechanoreceptors. Balance control of healthy individuals was assessed either when wearing a loaded vest or in normal-weight condition. In the Loaded condition, we observed decreased cortical activity over the primary somatosensory cortex (SI) for both an early P50-N90 somatosensory evoked potential (SEP) and for oscillatory brain activity within the gamma band (30–80 Hz). These reductions were interpreted as a disrupted early sensory transmission (i.e., decreased early SEP) leading to a decreased perception of plantar sole sensory information (i.e., decreased gamma band power). These early sensory mechanisms for the Loaded condition were associated with an increase in the late P170-N210 SEP and oscillatory brain activity within the beta band (19–24 Hz). These neural signatures involved areas which are engaged in sensorimotor integrative processes (secondary somatosensory cortex (SII) and right temporoparietal junction). Altered early and late sensory processes may result from the increase pressure on the mechanoreceptors of the foot sole and not from postural instability per se. Indeed, postural instability with normal weight condition did not lead to SEP changes. PMID:27445758

  4. Subliminal presentation of other faces (but not own face) primes behavioral and evoked cortical processing of empathy for pain.

    PubMed

    Ibáñez, Agustín; Hurtado, Esteban; Lobos, Alejandro; Escobar, Josefina; Trujillo, Natalia; Baez, Sandra; Huepe, David; Manes, Facundo; Decety, Jean

    2011-06-29

    Current research on empathy for pain emphasizes the overlap in the neural response between the first-hand experience of pain and its perception in others. However, recent studies suggest that the perception of the pain of others may reflect the processing of a threat or negative arousal rather than an automatic pro-social response. It can thus be suggested that pain processing of other-related, but not self-related, information could imply danger rather than empathy, due to the possible threat represented in the expressions of others (especially if associated with pain stimuli). To test this hypothesis, two experiments considering subliminal stimuli were designed. In Experiment 1, neutral and semantic pain expressions previously primed with own or other faces were presented to participants. When other-face priming was used, only the detection of semantic pain expressions was facilitated. In Experiment 2, pictures with pain and neutral scenarios previously used in ERP and fMRI research were used in a categorization task. Those pictures were primed with own or other faces following the same procedure as in Experiment 1 while ERPs were recorded. Early (N1) and late (P3) cortical responses between pain and no-pain were modulated only in the other-face priming condition. These results support the threat value of pain hypothesis and suggest the necessity for the inclusion of own- versus other-related information in future empathy for pain research. PMID:21624566

  5. Optical coherence tomography is less sensitive than visual evoked potentials in optic neuritis

    PubMed Central

    Naismith, R T.; Tutlam, N T.; Xu, J; Shepherd, J B.; Klawiter, E C.; Song, S -K.; Cross, A H.

    2009-01-01

    Objectives: Determine the utility of optical coherence tomography (OCT) to detect clinical and subclinical remote optic neuritis (ON), its relationship to clinical characteristics of ON and visual function, and whether the retinal nerve fiber layer (RNFL) thickness functions as a surrogate marker of global disease severity. Methods: Cross-sectional study of 65 subjects with at least 1 clinical ON episode at least 6 months prior. Measures included clinical characteristics, visual acuity (VA), contrast sensitivity (CS), OCT, and visual evoked potentials (VEP). Results: Ninety-six clinically affected optic nerves were studied. The sensitivity of OCT RNFL after ON was 60%, decreasing further with mild onset and good recovery. VEP sensitivity was superior at 81% (p = 0.002). Subclinical ON in the unaffected eye was present in 32%. VEP identified 75% of all subclinically affected eyes, and OCT identified <20%. RNFL thickness demonstrated linear correlations with VA (r = 0.65) and CS (r = 0.72) but was unable to distinguish visual categories <20/50. RNFL was thinner with severe onset and disease recurrence but was unaffected by IV glucocorticoids. OCT measurements were not related to overall disability, ethnicity, sex, or age at onset. The greatest predictor for RNFL in the unaffected eye was the RNFL in the fellow affected eye. Conclusions: Visual evoked potentials (VEP) remains the preferred test for detecting clinical and subclinical optic neuritis. Optical coherence tomography (OCT) measures were unrelated to disability and demographic features predicting a worse prognosis in multiple sclerosis. OCT may provide complementary information to VEP in select cases, and remains a valuable research tool for studying optic nerve disease in populations. GLOSSARY ANOVA = analysis of variance; CIS = clinically isolated syndrome; CS = contrast sensitivity; EDSS = Expanded Disability Status Score; logMAR = logarithm of the minimum angle of resolution; MS = multiple sclerosis; MSSS

  6. [Determination of irreversibility of clinical brain death. Electroencephalography and evoked potentials].

    PubMed

    Buchner, H; Ferbert, A

    2016-02-01

    Principally, in the fourth update of the rules for the procedure to finally determine the irreversible cessation of function of the cerebrum, the cerebellum and the brainstem, the importance of an electroencephalogram (EEG), somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) are confirmed. This paper presents the reliability and validity of the electrophysiological diagnosis, discusses the amendments in the fourth version of the guidelines and introduces the practical application, problems and sources of error.An EEG is the best established supplementary diagnostic method for determining the irreversibility of clinical brain death syndrome. It should be noted that residual brain activity can often persist for many hours after the onset of brain death syndrome, particularly in patients with primary brainstem lesions. The derivation and analysis of an EEG requires a high level of expertise to be able to safely distinguish artefacts from primary brain activity. The registration of EEGs to demonstrate the irreversibility of clinical brain death syndrome is extremely time consuming.The BAEPs can only be used to confirm the irreversibility of brain death syndrome in serial examinations or in the rare cases of a sustained wave I or sustained waves I and II. Very often, an investigation cannot be reliably performed because of existing sound conduction disturbances or failure of all potentials even before the onset of clinical brain death syndrome. This explains why BAEPs are only used in exceptional cases.The SEPs of the median nerve can be very reliably derived, are technically simple and with few sources of error. A serial investigation is not required and the time needed for examination is short. For these reasons SEPs are given preference over EEGs and BAEPs for establishing the irreversibility of clinical brain death syndrome. PMID:26785843

  7. Prenatal exposure to cannabinoids evokes long-lasting functional alterations by targeting CB1 receptors on developing cortical neurons

    PubMed Central

    de Salas-Quiroga, Adán; Díaz-Alonso, Javier; García-Rincón, Daniel; Remmers, Floortje; Vega, David; Gómez-Cañas, María; Lutz, Beat; Guzmán, Manuel; Galve-Roperh, Ismael

    2015-01-01

    The CB1 cannabinoid receptor, the main target of Δ9-tetrahydrocannabinol (THC), the most prominent psychoactive compound of marijuana, plays a crucial regulatory role in brain development as evidenced by the neurodevelopmental consequences of its manipulation in animal models. Likewise, recreational cannabis use during pregnancy affects brain structure and function of the progeny. However, the precise neurobiological substrates underlying the consequences of prenatal THC exposure remain unknown. As CB1 signaling is known to modulate long-range corticofugal connectivity, we analyzed the impact of THC exposure on cortical projection neuron development. THC administration to pregnant mice in a restricted time window interfered with subcerebral projection neuron generation, thereby altering corticospinal connectivity, and produced long-lasting alterations in the fine motor performance of the adult offspring. Consequences of THC exposure were reminiscent of those elicited by CB1 receptor genetic ablation, and CB1-null mice were resistant to THC-induced alterations. The identity of embryonic THC neuronal targets was determined by a Cre-mediated, lineage-specific, CB1 expression-rescue strategy in a CB1-null background. Early and selective CB1 reexpression in dorsal telencephalic glutamatergic neurons but not forebrain GABAergic neurons rescued the deficits in corticospinal motor neuron development of CB1-null mice and restored susceptibility to THC-induced motor alterations. In addition, THC administration induced an increase in seizure susceptibility that was mediated by its interference with CB1-dependent regulation of both glutamatergic and GABAergic neuron development. These findings demonstrate that prenatal exposure to THC has long-lasting deleterious consequences in the adult offspring solely mediated by its ability to disrupt the neurodevelopmental role of CB1 signaling. PMID:26460022

  8. Prenatal exposure to cannabinoids evokes long-lasting functional alterations by targeting CB1 receptors on developing cortical neurons.

    PubMed

    de Salas-Quiroga, Adán; Díaz-Alonso, Javier; García-Rincón, Daniel; Remmers, Floortje; Vega, David; Gómez-Cañas, María; Lutz, Beat; Guzmán, Manuel; Galve-Roperh, Ismael

    2015-11-01

    The CB1 cannabinoid receptor, the main target of Δ(9)-tetrahydrocannabinol (THC), the most prominent psychoactive compound of marijuana, plays a crucial regulatory role in brain development as evidenced by the neurodevelopmental consequences of its manipulation in animal models. Likewise, recreational cannabis use during pregnancy affects brain structure and function of the progeny. However, the precise neurobiological substrates underlying the consequences of prenatal THC exposure remain unknown. As CB1 signaling is known to modulate long-range corticofugal connectivity, we analyzed the impact of THC exposure on cortical projection neuron development. THC administration to pregnant mice in a restricted time window interfered with subcerebral projection neuron generation, thereby altering corticospinal connectivity, and produced long-lasting alterations in the fine motor performance of the adult offspring. Consequences of THC exposure were reminiscent of those elicited by CB1 receptor genetic ablation, and CB1-null mice were resistant to THC-induced alterations. The identity of embryonic THC neuronal targets was determined by a Cre-mediated, lineage-specific, CB1 expression-rescue strategy in a CB1-null background. Early and selective CB1 reexpression in dorsal telencephalic glutamatergic neurons but not forebrain GABAergic neurons rescued the deficits in corticospinal motor neuron development of CB1-null mice and restored susceptibility to THC-induced motor alterations. In addition, THC administration induced an increase in seizure susceptibility that was mediated by its interference with CB1-dependent regulation of both glutamatergic and GABAergic neuron development. These findings demonstrate that prenatal exposure to THC has long-lasting deleterious consequences in the adult offspring solely mediated by its ability to disrupt the neurodevelopmental role of CB1 signaling. PMID:26460022

  9. Laser-evoked potentials as a tool for assessing the efficacy of antinociceptive drugs

    PubMed Central

    Truini, A.; Panuccio, G.; Galeotti, F.; Maluccio, M.R.; Sartucci, F.; Avoli, M.; Cruccu, G.

    2016-01-01

    Laser-evoked potentials (LEPs) are brain responses to laser radiant heat pulses and reflect the activation of Aδ nociceptors. LEPs are to date the reference standard technique for studying nociceptive pathway function in patients with neuropathic pain. To find out whether LEPs also provide a useful neurophysiological tool for assessing antinociceptive drug efficacy, in this double-blind placebo-controlled study we measured changes induced by the analgesic tramadol on LEPs in 12 healthy subjects. We found that tramadol decreased the amplitude of LEPs, whereas placebo left LEPs unchanged. The opioid antagonist naloxone partially reversed the tramadol-induced LEP amplitude decrease. We conclude that LEPs may be reliably used in clinical practice and research for assessing the efficacy of antinociceptive drugs. PMID:19477145

  10. Vertex potentials evoked during auditory signal detection - Relation to decision criteria

    NASA Technical Reports Server (NTRS)

    Squires, K. C.; Hillyard, S. A.; Lindsay, P. H.

    1973-01-01

    Vertex potentials were recorded from eight subjects performing in an auditory threshold detection task with rating scale responses. The amplitudes and latencies of both the N1 and the late positive (P3) components were found to vary systematically with the criterion level of the decision. These changes in the waveshape of the N1 component were comparable to those produced by varying the signal intensity in a passive condition, but the late positive component in the active task was not similarly related to the passively evoked P2 component. It was suggested that the N1 and P3 components represent distinctive aspects of the decision process, with N1 signifying the quantity of signal information received and P3 reflecting the certainty of the decision based upon that information.

  11. The pontomesencephalic tegmentum delays the peak latency of the visual evoked potential in rats.

    PubMed

    Bringmann, A

    1995-12-29

    In previous experiments it was found that physostigmine application in unrestrained rats delayed the peak latency of the visual evoked potential (VEP). The present study was carried out to find the putative site that cholinergically mediates the latency delay of rat's VEP. After unilateral ibotenic acid lesions of the nucleus basalis magnocellularis (NBM) and the pedunculopontine tegmental nucleus (PPTg), respectively, the VEPs of freely moving rats were recorded in different behavioural states. While NBM lesion did not alter the behavioural modulation of the VEP latency, the PPTg lesion produced shorter VEP latencies in the occipital cortex of the lesioned hemisphere in high and moderate arousal states. The peak latency shortening was significant for exploratory sniffing. Physostigmine but not nicotine application abolished the shorter VEP latency. The results indicate a muscarinic mechanism within the pontomesencephalic tegmentum that ipsilaterally delayed the VEP latency in high and moderate but not in low arousal states. PMID:8787819

  12. 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

    2014-01-01

    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. PMID:24828128

  13. Abnormal visual-evoked potentials in leukemic children after cranial radiation

    SciTech Connect

    Russo, A.; Tomarchio, S.; Pero, G.; Consoli, G.; Marina, R.; Rizzari, C.; Schiliro, G.

    1985-01-01

    Visual-evoked potentials (VEPs) were studied in 55 asymptomatic children with leukemia or solid tumors in remission in order to detect subclinical demyelination of the optic pathway after CNS prophylaxis. In group I (11 patients with ALL studied prospectively), VEP latency was increased in ten after cranial radiation (CR) as compared with previous values. Group II (18 patients with ALL in maintenance) and group III (16 patients with ALL off therapy) were studied retrospectively and VEP latency was found above normal limits in 33 and 31%, respectively. In group IV (four patients with solid tumors and six with leukemia, all of whom received no CR), VEP latency was normal despite periodical intrathecal methotrexate administrations to five of them. The authors conclude that CR determines a slowing of conduction on VEP test, probably due to demyelination of the optic pathway, in a high proportion of patients. The future clinical significance of these findings must be established throughout a prolonged follow-up period.

  14. Comparison of acuity tests and pattern evoked potential criteria: two mechanisms underly acuity maturation in man.

    PubMed

    Spekreijse, H

    1983-10-01

    A comparative study of acuity tests and pattern evoked potential (EP) criteria was performed on a total of 307 subjects, 214 of them at an age between 2 months post-term and 12 years. All were examined ophthalmologically prior to testing. It was shown that both psychophysical and EP estimated acuity improve in the same way until puberty. From birth to about 6 months a rapid improvement is found. This fast phase can probably be attributed to retinal morphological maturation. During this period a fair estimate of acuity can be obtained by determining the checksize that yields the largest EP; a conclusion of practical importance for screening. The subsequent slow improvement phase, which ends around puberty, is reflected in the development of the waveform of the pattern onset EP. Since it correlates with the growth of a spatial contrast specific component of extrastriate origin in the EP, the slow improvement phase most likely reflects maturation of central processes. PMID:6639719

  15. The N2-P3 complex of the evoked potential and human performance

    NASA Technical Reports Server (NTRS)

    Odonnell, Brian F.; Cohen, Ronald A.

    1988-01-01

    The N2-P3 complex and other endogenous components of human evoked potential provide a set of tools for the investigation of human perceptual and cognitive processes. These multidimensional measures of central nervous system bioelectrical activity respond to a variety of environmental and internal factors which have been experimentally characterized. Their application to the analysis of human performance in naturalistic task environments is just beginning. Converging evidence suggests that the N2-P3 complex reflects processes of stimulus evaluation, perceptual resource allocation, and decision making that proceed in parallel, rather than in series, with response generation. Utilization of these EP components may provide insights into the central nervous system mechanisms modulating task performance unavailable from behavioral measures alone. The sensitivity of the N2-P3 complex to neuropathology, psychopathology, and pharmacological manipulation suggests that these components might provide sensitive markers for the effects of environmental stressors on the human central nervous system.

  16. Respiratory sensory gating measured by respiratory-related evoked potentials in generalized anxiety disorder

    PubMed Central

    Chan, Pei-Ying S.; Cheng, Chia-Hsiung; Hsu, Shih-Chieh; Liu, Chia-Yih; Davenport, Paul W.; von Leupoldt, Andreas

    2015-01-01

    The perception of respiratory sensations plays an important role both in respiratory diseases and in anxiety disorders. However, little is known about the neural processes underlying respiratory sensory perception, especially in patient groups. Therefore, the present study examined whether patients with generalized anxiety disorder (GAD) would demonstrate altered respiratory sensory gating compared to a healthy control group. Respiratory-related evoked potentials (RREP) were measured in a paired inspiratory occlusion paradigm presenting two brief occlusion stimuli (S1 and S2) within one inspiration. The results showed a significantly greater S2/S1 ratio for the N1 component of the RREP in the GAD group compared to the control group. Our findings suggest altered respiratory sensory processing in patients with GAD, which might contribute to altered perception of respiratory sensations in these patients. PMID:26217278

  17. Slow negative evoked potentials in the rhesus monkey (Macaca mulatta): myogenic versus neurogenic influences.

    PubMed

    Fria, T J; Saad, M M; Doyle, W J; Cantekin, E I

    1984-02-01

    The influence of myogenic activity on the generation of slow negative evoked potentials (SN10) to octave, toneburst stimuli (0.5-2 Hz) was investigated in 5 rhesus monkeys (M. mulatta) by comparing responses obtained prior to and during total paralysis induced with curare. The SN10 could be easily elicited during paralysis, regardless of stimulus intensity, rate, or frequency. During paralysis, there were no systematic changes in either response latency or amplitude; variability in latency was less than 10% and changes in response amplitude were within 30%. These findings suggest that the myogenic contribution to the SN10 response is negligible and that this response is of neurogenic origin in the rhesus monkey. PMID:6198169

  18. 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.

  19. Effect of refractive error on visual evoked potentials with pattern stimulation in dogs.

    PubMed

    Ito, Yosuke; Maehara, Seiya; Itoh, Yoshiki; Matsui, Ai; Hayashi, Miri; Kubo, Akira; Uchide, Tsuyoshi

    2016-04-01

    The purpose of this study was to investigate the effects of refractive error on canine visual evoked potentials with pattern stimulation (P-VEP). Six normal beagle dogs were used. The refractive power of the recorded eyes was measured by skiascopy. The refractive power was corrected to -4 diopters (D) to +2 D using contact lens. P-VEP was recorded at each refractive power. The stimulus pattern size and distance were 50.3 arc-min and 50 cm. The P100 appeared at almost 100 msec at -2 D (at which the stimulus monitor was in focus). There was significant prolongation of the P100 implicit time at -4, -3, 0 and +1 D compared with -2 D, respectively. We concluded that the refractive power of the eye affected the P100 implicit time in canine P-VEP recording. PMID:26655769

  20. Ageing Effect on Air-Conducted Ocular Vestibular Evoked Myogenic Potential

    PubMed Central

    Bhat, Jayashree S.; Sequeira, Nimalka Maria; Bhojwani, Kiran M.

    2015-01-01

    One of the recent diagnostic tests to assess the function of otolithic organs is through vestibular evoked myogenic potential (VEMP) testing. There are equivocal findings on effect of aging on ocular VEMP (oVEMP) parameters with reference to latencies. Hence this study was taken up to investigate the age related changes in oVEMP parameters. This present study considered 30 participants in each age group i.e., young adults, middle-aged adults and older adults. oVEMP were recorded using insert earphone at 100dBnHL at 500hZ short duration tone burst. The results showed in older adult significant difference in response rate, latencies and amplitude as compared to young and middle adult. Hence age should be taken into consideration when interpreting oVEMP results. PMID:26779326

  1. Steady state visually evoked potential correlates of auditory hallucinations in schizophrenia.

    PubMed

    Line, P; Silberstein, R B; Wright, J J; Copolov, D L

    1998-11-01

    This study attempted to localize regions of brain electrical activity associated with the onset of auditory hallucinations. Changes in Steady State Visually Evoked Potential (SSVEP) topography associated with the onset of spontaneous auditory hallucinations was studied in eight schizophrenic patients. The SSVEP elicited by a spatially uniform sinusoidally varying visual flicker was recorded using a 64-channel electrode helmet. A large and significant decrease in SSVEP latency in the right temporo/parietal region occurred in the second prior to the report of auditory hallucinations. A control task with matching motor movements produced no significant decrease in SSVEP latency in the same right temporo/parietal location. This finding suggests that activity of fine temporal resolution in the neural networks in the right temporo/parietal area may be implicated in the genesis of auditory hallucination, in conformity with certain neuropsychological theories. PMID:9811555

  2. Neural network-based diagnosing for optic nerve disease from visual-evoked potential.

    PubMed

    Kara, Sadik; Güven, Ayşegül

    2007-10-01

    In this paper, we purpose a diagnostic procedure to identify the optic nerve disease from visual evoked potential (VEP) signals using an Artificial Neural Network (ANN). Multilayer feed forward ANN trained with a Levenberg Marquart backpropagation algorithm was implemented. The correct classification rate was 96.87% for subjects having optic nerve disease and 96.66% for healthy subjects. The end results are classified as healthy and diseased. Testing results were found to be compliant with the expected results that are derived from the physician's direct diagnosis, angiography, VEP and pattern electroretinography. The stated results show that the proposed method could point out the ability of design of a new intelligent assistance diagnosis system. PMID:17918693

  3. Learned control over spinal nociception reduces supraspinal nociception as quantified by late somatosensory evoked potentials.

    PubMed

    Ruscheweyh, Ruth; Bäumler, Maximilian; Feller, Moritz; Krafft, Stefanie; Sommer, Jens; Straube, Andreas

    2015-12-01

    We have recently shown that subjects can learn to use cognitive-emotional strategies to suppress their spinal nociceptive flexor reflex (RIII reflex) under visual RIII feedback and proposed that this reflects learned activation of descending pain inhibition. Here, we investigated whether learned RIII suppression also affects supraspinal nociception and whether previous relaxation training increases success. Subjects were trained over 3 sessions to reduce their RIII size by self-selected cognitive-emotional strategies. Two groups received true RIII feedback (with or without previous relaxation training) and a sham group received false feedback (15 subjects per group). RIII reflexes, late somatosensory evoked potentials (SEPs), and F-waves were recorded and pain intensity ratings collected. Both true feedback groups achieved significant (P < 0.01) but similar RIII suppression (to 79% ± 21% and 70% ± 17% of control). Somatosensory evoked potential amplitude (100-150 milliseconds after stimulation) was reduced in parallel with the RIII size (r = 0.57, P < 0.01). In the sham group, neither RIII size nor SEP amplitude was significantly reduced during feedback training. Pain intensity was significantly reduced in all 3 groups and also correlated with RIII reduction (r = 0.44, P < 0.01). F-wave parameters were not affected during RIII suppression. The present results show that learned RIII suppression also affects supraspinal nociception as quantified by SEPs, although effects on pain ratings were less clear. Lower motor neuron excitability as quantified by F-waves was not affected. Previous relaxation training did not significantly improve RIII feedback training success. PMID:26270584

  4. In-vitro characterization of a cochlear implant system for recording of evoked compound action potentials

    PubMed Central

    2012-01-01

    Background Modern cochlear implants have integrated recording systems for measuring electrically evoked compound action potentials of the auditory nerve. The characterization of such recording systems is important for establishing a reliable basis for the interpretation of signals acquired in vivo. In this study we investigated the characteristics of the recording system integrated into the MED-EL PULSARCI100 cochlear implant, especially its linearity and resolution, in order to develop a mathematical model describing the recording system. Methods In-vitro setup: The cochlear implant, including all attached electrodes, was fixed in a tank of physiologic saline solution. Sinusoidal signals of the same frequency but with different amplitudes were delivered via a signal generator for measuring and recording on a single electrode. Computer simulations: A basic mathematical model including the main elements of the recording system, i.e. amplification and digitalization stage, was developed. For this, digital output for sinusoidal input signals of different amplitudes were calculated using in-vitro recordings as reference. Results Using an averaging of 100 measurements the recording system behaved linearly down to approximately -60 dB of the input signal range. Using the same method, a system resolution of 10 μV was determined for sinusoidal signals. The simulation results were in very good agreement with the results obtained from in-vitro experiments. Conclusions The recording system implemented in the MED-EL PULSARCI100 cochlear implant for measuring the evoked compound action potential of the auditory nerve operates reliably. The developed mathematical model provides a good approximation of the recording system. PMID:22531599

  5. Early abnormalities of evoked potentials and future disability in patients with multiple sclerosis.

    PubMed

    Kallmann, B A; Fackelmann, S; Toyka, K V; Rieckmann, P; Reiners, K

    2006-02-01

    Evoked potentials (EP) have a role in making the diagnosis of multiple sclerosis (MS) but their implication for predicting the future disease course in MS is under debate. EP data of 94 MS patients examined at first presentation, and after five and ten years were retrospectively analysed. Patients were divided into two groups in relation to the prior duration of disease at the time point of first examination: group 1 patients (n=44) were first examined within two years after disease onset, and group 2 patients (n=50) at later time points. As primary measures sum scores were calculated for abnormalities of single and combined EP (visual (VEP), somatosensory (SEP), magnetic motor evoked potentials (MEP)). In patients examined early after disease onset (group 1), a significant predictive value for abnormal EP was found with MEP and SEP sum scores at first presentation correlating significantly with Expanded Disability Status Scale (EDSS) values after five years, while the VEP sum score was not. The cumulative number of abnormal MEP, SEP and VEP results also indicated higher degrees of disability (EDSS > or = 3.5) after five years. Combined pathological SEP and MEP findings at first presentation best predicted clinical disability (EDSS > or = 3.5) after five years (odds ratio 11.0). EP data and EDSS at first presentation were not significantly linked suggesting that EP abnormalities at least in part represented clinically silent lesions not mirrored by EDSS. For patients in later disease phases (group 2), no significant associations between EP data at first presentation and EDSS at five and ten years were detected. Together with clinical findings and MR imaging, combined EP data may help to identify patients at high risk of long-term clinical deterioration and guide decisions as to immunomodulatory treatment. PMID:16459720

  6. Cortical folding and the potential for prognostic neuroimaging in schizophrenia

    PubMed Central

    Guo, Shuixia; Iwabuchi, Sarina; Balain, Vijender; Feng, Jianfeng; Liddle, Peter; Palaniyappan, Lena

    2015-01-01

    In 41 patients with schizophrenia, we used neuroanatomical information derived from structural imaging to identify patients with more severe illness, characterised by high symptom burden, low processing speed, high degree of illness persistence and lower social and occupational functional capacity. Cortical folding, but not thickness or volume, showed a high discriminatory ability in correctly identifying patients with more severe illness. PMID:26206860

  7. Cortical folding and the potential for prognostic neuroimaging in schizophrenia.

    PubMed

    Guo, Shuixia; Iwabuchi, Sarina; Balain, Vijender; Feng, Jianfeng; Liddle, Peter; Palaniyappan, Lena

    2015-11-01

    In 41 patients with schizophrenia, we used neuroanatomical information derived from structural imaging to identify patients with more severe illness, characterised by high symptom burden, low processing speed, high degree of illness persistence and lower social and occupational functional capacity. Cortical folding, but not thickness or volume, showed a high discriminatory ability in correctly identifying patients with more severe illness. PMID:26206860

  8. Effects of left primary motor and dorsolateral prefrontal cortex transcranial direct current stimulation on laser-evoked potentials in migraine patients and normal subjects.

    PubMed

    Vecchio, Eleonora; Ricci, Katia; Montemurno, Anna; Delussi, Marianna; Invitto, Sara; de Tommaso, Marina

    2016-07-28

    Migraine is characterized by an altered cortical excitability. Because transcranial direct current stimulation (tDCS) can change brain activity noninvasively, it is possible to hypothesize its efficacy in modulating pain in migraine. In this study, we compared the effects of tDCS of the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) both on subjective pain and on evoked responses induced by laser stimulation (LEPs). Thirty-two patients and sixteen controls were randomized to receive sham stimulation and real tDCS with the anode centered over M1 or DLPFC. Laser Evoked potentials were recorded in basal, sham and tDCS conditions. We did not find significant acute changes in LEPs parameters and pain perception among subjects who received tDCS of both M1 and DLPFC. After DLPFC tDCS, we observed a significant increase of N2-P2 component habituation in migraine patients while M1 stimulation reduced it. These findings may suggest a modulation of abnormal pain processing induced by DLPFC and M1 anodal tDCS and outline the need for future investigations exploring the possible neuronal plasticity changes supporting the clinical effect on migraine. PMID:27208831

  9. Combination of blood oxygen level–dependent functional magnetic resonance imaging and visual evoked potential recordings for abnormal visual cortex in two types of amblyopia

    PubMed Central

    Wang, Xinmei; Cui, Dongmei; Zheng, Ling; Yang, Xiao; Yang, Hui

    2012-01-01

    Purpose To elucidate the different neuromechanisms of subjects with strabismic and anisometropic amblyopia compared with normal vision subjects using blood oxygen level–dependent functional magnetic resonance imaging (BOLD-fMRI) and pattern-reversal visual evoked potential (PR-VEP). Methods Fifty-three subjects, age range seven to 12 years, diagnosed with strabismic amblyopia (17 cases), anisometropic amblyopia (20 cases), and normal vision (16 cases), were examined using the BOLD-fMRI and PR-VEP of UTAS-E3000 techniques. Cortical activation by binocular viewing of reversal checkerboard patterns was examined in terms of the calcarine region of interest (ROI)-based and spatial frequency–dependent analysis. The correlation of cortical activation in fMRI and the P100 amplitude in VEP were analyzed using the SPSS 12.0 software package. Results In the BOLD-fMRI procedure, reduced areas and decreased activation levels were found in Brodmann area (BA) 17 and other extrastriate areas in subjects with amblyopia compared with the normal vision group. In general, the reduced areas mainly resided in the striate visual cortex in subjects with anisometropic amblyopia. In subjects with strabismic amblyopia, a more significant cortical impairment was found in bilateral BA 18 and BA 19 than that in subjects with anisometropic amblyopia. The activation by high-spatial-frequency stimuli was reduced in bilateral BA 18 and 19 as well as BA 17 in subjects with anisometropic amblyopia, whereas the activation was mainly reduced in BA 18 and BA 19 in subjects with strabismic amblyopia. These findings were further confirmed by the ROI-based analysis of BA 17. During spatial frequency–dependent VEP detection, subjects with anisometropic amblyopia had reduced sensitivity for high spatial frequency compared to subjects with strabismic amblyopia. The cortical activation in fMRI with the calcarine ROI-based analysis of BA 17 was significantly correlated with the P100 amplitude in VEP

  10. Dysfunctional cortical inhibition in adult ADHD: neural correlates in auditory event-related potentials.

    PubMed

    Schubert, J K; Gonzalez-Trejo, E; Retz, W; Rösler, M; Corona-Strauss, F I; Steidl, G; Teuber, T; Strauss, D J

    2014-09-30

    In recent times, the relevance of an accurate diagnosis of attention-deficit/hyperactivity disorder (ADHD) in adults has been the focus of several studies. No longer considered a pathology exclusive to children and adolescents, and taking into account its social implications, developing enhanced support tools for the current diagnostic procedure becomes a priority. Here we present a method for the objective assessment of ADHD in adults using chirp-evoked, paired auditory late responses (ALRs) combined with a two-dimensional ALR denoising scheme to extract correlates of intracortical inhibition. Our method allows for an effective single-sweep denoising, thus requiring less trials to obtain recognizable physiological features, useful as pointers of cortical impairment. Results allow an optimized diagnosis, reduction of data loss and acquisition time; moreover, they do not account exclusively for critical elements within clinical evaluations, but also allow studying the pathophysiology of the condition by providing objective information regarding impaired cortical functions. PMID:25033725

  11. Usefulness of the Combined Motor Evoked and Somatosensory Evoked Potentials for the Predictive Index of Functional Recovery After Primary Pontine Hemorrhage

    PubMed Central

    Seong, Jin Wan; Kim, Min Ho; Shin, Hyo Keong; Lee, Han Do; Park, Jun Bum

    2014-01-01

    Objective To investigate the predictive index of functional recovery after primary pontine hemorrhage (PPH) using the combined motor evoked potential (MEP) and somatosensory evoked potential (SEP) in comparison to the hematoma volume and transverse diameter measured with computerized tomography. Methods Patients (n=14) with PPH were divided into good- and poor-outcome groups according to the modified Rankin Score (mRS). We evaluated clinical manifestations, radiological characteristics, and the combined MEP and SEP responses. The summed MEP and SEP (EP sum) was compared to the hematoma volume and transverse diameter predictive index of global disability, gait ability, and trunk stability in sitting posture. Results All measures of functional status and radiological parameters of the good-outcome group were significantly better than those of the poor-outcome group. The EP sum showed the highest value for the mRS and functional ambulatory category, and transverse diameter showed the highest value for "sitting-unsupported" of Berg Balance Scale. Conclusion The combined MEP and SEP is a reliable and useful tool for functional recovery after PPH. PMID:24639921

  12. Giant somatosensory evoked potentials in a patient with the anterior spinal artery syndrome.

    PubMed

    Triggs, W J; Berić, A

    1993-05-01

    We studied a previously healthy 25-year-old woman with the anterior spinal artery syndrome, a rare thoracocervical myelopathy with multiple potential etiologies. Quantitative and clinical sensory examination showed dissociated loss of pin-prick and temperature discrimination below the level of the lesion, with normal light touch, vibratory, and position sense. Magnetic resonance imaging was consistent with cervical spinal cord infarction. Median SEPs showed normal Erb's potential with absent spinal N13- and normal scalp N20- latency. Tibial SEPs showed normal lumbosacral responses and normal scalp P30- latency. Both median and tibial nerve stimulation produced cortical responses of unusually large amplitude (median 38 microV, tibial 17 microV). We hypothesize that large SEP amplitudes in this patient resulted from loss of anterolateral inhibitory influences on the dorsal column-medial lemniscal system. PMID:8515757

  13. Cortical Auditory Event Related Potentials (P300) for Frequency Changing Dynamic Tones

    PubMed Central

    Kalaiah, Mohan Kumar

    2016-01-01

    Background and Objectives P300 has been studied with a variety of stimuli. However, the nature of P300 has not been investigated for deviant stimuli which change its characteristics from standard stimuli after a period of time from onset. Subjects and Methods Nine young adults with normal hearing participated in the study. The P300 was elicited using an oddball paradigm, the probability of standard and deviant stimuli was 80% and 20% respectively. Six stimuli were used to elicit P300, it included two pure-tones (1,000 Hz and 2,000 Hz) and four tone-complexes (tones with frequency changes). Among these stimuli, 1,000 Hz tone served as standard while others served as deviant stimuli. The P300 was recorded in five separate blocks, with one of the deviant stimuli as target in each block. Electroencephalographic was recorded from electrode sites Fz, Cz, C3, C4, and Pz. Latency and amplitude of components of the cortical auditory evoked potentials were measured at Cz. Results Waveforms obtained in the present study shows that, all the deviant stimuli elicited obligatory P1-N1-P2 for stimulus onset. 2,000 Hz deviant tone elicited P300 at a latency of 300 ms. While, tone-complexes elicited acoustic change complex (ACC) for frequency changes and finally elicited P300 at a latency of 600 ms. In addition, the results showed shorter latency and larger amplitude ACC and P300 for rising tone-complexes compared to falling tone-complexes. Conclusions Tone-complexes elicited distinct waveforms compared to 2,000 Hz deviant tone. Rising tone-complexes which had an increase in frequency elicited shorter latency and larger amplitude responses, which could be attributed to perceptual bias for frequency changes. PMID:27144230

  14. 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

  15. 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

  16. Using evoked potentials to match interaural electrode pairs with bilateral cochlear implants.

    PubMed

    Smith, Zachary M; Delgutte, Bertrand

    2007-03-01

    Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency-channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable. PMID:17225976

  17. Using Evoked Potentials to Match Interaural Electrode Pairs with Bilateral Cochlear Implants

    PubMed Central

    Delgutte, Bertrand

    2007-01-01

    Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency–channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable. PMID:17225976

  18. Effect of higher frequency on the classification of steady-state visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Won, Dong-Ok; Hwang, Han-Jeong; Dähne, Sven; Müller, Klaus-Robert; Lee, Seong-Whan

    2016-02-01

    Objective. Most existing brain-computer interface (BCI) designs based on steady-state visual evoked potentials (SSVEPs) primarily use low frequency visual stimuli (e.g., <20 Hz) to elicit relatively high SSVEP amplitudes. While low frequency stimuli could evoke photosensitivity-based epileptic seizures, high frequency stimuli generally show less visual fatigue and no stimulus-related seizures. The fundamental objective of this study was to investigate the effect of stimulation frequency and duty-cycle on the usability of an SSVEP-based BCI system. Approach. We developed an SSVEP-based BCI speller using multiple LEDs flickering with low frequencies (6-14.9 Hz) with a duty-cycle of 50%, or higher frequencies (26-34.7 Hz) with duty-cycles of 50%, 60%, and 70%. The four different experimental conditions were tested with 26 subjects in order to investigate the impact of stimulation frequency and duty-cycle on performance and visual fatigue, and evaluated with a questionnaire survey. Resting state alpha powers were utilized to interpret our results from the neurophysiological point of view. Main results. The stimulation method employing higher frequencies not only showed less visual fatigue, but it also showed higher and more stable classification performance compared to that employing relatively lower frequencies. Different duty-cycles in the higher frequency stimulation conditions did not significantly affect visual fatigue, but a duty-cycle of 50% was a better choice with respect to performance. The performance of the higher frequency stimulation method was also less susceptible to resting state alpha powers, while that of the lower frequency stimulation method was negatively correlated with alpha powers. Significance. These results suggest that the use of higher frequency visual stimuli is more beneficial for performance improvement and stability as time passes when developing practical SSVEP-based BCI applications.

  19. 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…

  20. [Long-term potentiation and unit evoked responses in the cingulate cortex of freely moving rats].

    PubMed

    Gorkin, A G; Reymann, K G; Aleksandrov, Iu I

    2002-01-01

    Long-term potentiation (LTP) of synaptic efficacy is considered to be the most probable physiological mechanism of long-term memory. However, lack of understanding of cellular and subcellular mechanisms of LTP induction in freely behaving animals does not correspond to the importance of the problem. It was tested whether the characteristics of potentiation in the cingulate cortex after tetanization of the subiculocingulate tract (SCT) meet the criteria of true LTP (that passes all known stages in its development and lasts for more than a day in freely-behaving animals). Additionally, characteristics of spike responses to SCT stimulation and the effects of application of different glutamate receptor blockers were studied. Without application of GABA receptor blockers, the LTP lasted for more than 24 hours. Application of NMDA glutamate receptor blockers significantly inhibited field potentials evoke by testing stimulation. Short-latency spike responses to SCT stimulation were recorded with low probability that increased with stimulation intensity. The obtained data reveal the possibility to compare the involvement of cingulate neurons in acquisition of adaptive behavior and changes in their spike responses during the LTP development in freely-moving rats. PMID:12528373

  1. 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. PMID:26493491

  2. Gravity-induced changes in intracellular potentials in elongating cortical cells of mung bean roots

    NASA Technical Reports Server (NTRS)

    Ishikawa, H.; Evans, M. L.

    1990-01-01

    Gravity-induced changes in intracellular potentials in primary roots of 2-day-old mung bean (Vigna mungo L. cv. black matpe) seedlings were investigated using glass microelectrodes held by 3-dimensional hydraulic micro-drives. The electrodes were inserted into outer cortical cells within the elongation zone. Intracellular potentials, angle of root orientation with respect to gravity, and position within the root of the impaled cortical cell were measured simultaneously. Gravistimulation caused intracellular potential changes in cortical cells of the elongation zone. When the roots were oriented vertically, the intracellular potentials of the outer cortical cells (2 mm behind the root apex) were approximately - 115 mV. When the roots were placed horizontally cortical cells on the upper side hyperpolarized to - 154 mV within 30 s while cortical cells on the lower side depolarized to about - 62 mV. This electrical asymmetry did not occur in cells of the maturation zone. Because attempts to insert the electrode into cells of the root cap were unsuccessful, these cells were not measured. The hyperpolarization of cortical cells on the upper side was greatly reduced upon application of N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of respiratory energy coupling. When stimulated roots were returned to the vertical, the degree of hyperpolarization of cortical cells on the previous upper side decreased within 30 s and approached that of cortical cells in non-stimulated roots. This cycle of hyperpolarization/loss of hyperpolarization was repeatable at least ten times by alternately turning the root from the vertical to the horizontal and back again. The very short (<30 s) lag period of these electrical changes indicates that they may result from stimulus-perception and transduction within the elongation zone rather than from transmission of a signal from the root cap.

  3. Gravity-induced changes in intracellular potentials in elongating cortical cells of mung bean roots.

    PubMed

    Ishikawa, H; Evans, M L

    1990-06-01

    Gravity-induced changes in intracellular potentials in primary roots of 2-day-old mung bean (Vigna mungo L. cv. black matpe) seedlings were investigated using glass microelectrodes held by 3-dimensional hydraulic micro-drives. The electrodes were inserted into outer cortical cells within the elongation zone. Intracellular potentials, angle of root orientation with respect to gravity, and position within the root of the impaled cortical cell were measured simultaneously. Gravistimulation caused intracellular potential changes in cortical cells of the elongation zone. When the roots were oriented vertically, the intracellular potentials of the outer cortical cells (2 mm behind the root apex) were approximately - 115 mV. When the roots were placed horizontally cortical cells on the upper side hyperpolarized to - 154 mV within 30 s while cortical cells on the lower side depolarized to about - 62 mV. This electrical asymmetry did not occur in cells of the maturation zone. Because attempts to insert the electrode into cells of the root cap were unsuccessful, these cells were not measured. The hyperpolarization of cortical cells on the upper side was greatly reduced upon application of N,N'-dicyclohexylcarbodiimide (DCCD), an inhibitor of respiratory energy coupling. When stimulated roots were returned to the vertical, the degree of hyperpolarization of cortical cells on the previous upper side decreased within 30 s and approached that of cortical cells in non-stimulated roots. This cycle of hyperpolarization/loss of hyperpolarization was repeatable at least ten times by alternately turning the root from the vertical to the horizontal and back again. The very short (<30 s) lag period of these electrical changes indicates that they may result from stimulus-perception and transduction within the elongation zone rather than from transmission of a signal from the root cap. PMID:11537168

  4. Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception.

    PubMed Central

    Frøbert, O; Arendt-Nielsen, L; Bak, P; Funch-Jensen, P; Bagger, J P

    1995-01-01

    Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus. PMID:8549932

  5. 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...

  6. 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…

  7. Longitudinal Study of Averaged Auditory Evoked Potentials in Normal Children from Birth to Three Years of Age.

    ERIC Educational Resources Information Center

    Ohlrich, Elizabeth S.; And Others

    This study examined individual patterns of the maturation of auditory evoked potential (AEP) in normal infants to determine whether longitudinal data show less variability than cross-sectional data, and to further assess the effect of stage of sleep on AEP. The AEPs for 10 children were examined by repeated testing between the ages of about two…

  8. Effect of sodium tungstate on visual evoked potentials in diabetic rats

    PubMed Central

    Bulut, Mehmet; Dönmez, Barış Özgür; Öztürk, Nihal; Başaranlar, Göksun; Kencebay Manas, Ceren; Derin, Narin; Özdemir, Semir

    2016-01-01

    AIM To evaluate the effect of sodium tungstate on visual evoked potentials (VEPs) in diabetic rats. METHODS Wistar rats were randomly divided into three groups as normal control, diabetic control and diabetic rats treated with sodium tungstate. Diabetes was induced by single intraperitoneal injection of streptozotocin (50 mg/kg). Sodium tungstate [40 mg/(kg·d)] was administered for 12wk and then VEPs were recorded. Additionally, thiobarbituric acid reactive substance (TBARS) levels were measured in brain tissues. RESULTS The latencies of P1, N1, P2, N2 and P3 waves were significantly prolonged in diabetic rats compared with control group. Diabetes mellitus caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. However, prolonged latencies of VEPs for all components returned to control levels in sodium tungstate-treated group. The treatment of sodium tungstate significantly decreased brain TBARS levels and depleted the prolonged latencies of VEP components compared with diabetic control group. CONCLUSION Sodium tungstate shows protective effects on visual pathway in diabetic rats, and it can be worthy of further study for potential use. PMID:27275420

  9. Effect of intrathecal bupivacaine on somatosensory evoked potentials following dermatomal stimulation.

    PubMed

    Lund, C; Selmar, P; Hansen, O B; Kehlet, H

    1987-09-01

    The effect of spinal anesthesia with 3.6 +/- 0.1 ml (mean +/- SEM) of 0.5% bupivacaine on early (less than 150 msec) somatosensory evoked potentials (SEPs) with electrical stimulation of the L1 and S1 dermatomes was examined in 12 patients. The mean level of sensory analgesia (pinprick) was T8,9 +/- 1.0 (+/- SEM) and the mean degree of motor blockade was 1.3 +/- 0.1 (Bromage scale). Intrathecal bupivacaine significantly (P less than 0.05) decreased the amplitude of all SEP components after stimulation of the L1 dermatome and most components during stimulation of the S1 dermatome. Intrathecal bupivacaine also increased the latency of SEPs (P less than 0.05) of both dermatomes. The L1 SEP disappeared in 7 and the S1 SEPs in 5 of the 12 patients during neural blockade. In three patients the SEPs disappeared at both locations. Sensory thresholds increased significantly during blockade. We found no correlation between decrease of amplitude and degree of motor blockade or level of sensory analgesia. Thus, intrathecal plain bupivacaine has a strong depressant effect on the neural afferent transmission as assessed by SEPs. However, despite clinically effective blockade as assessed by pinprick and motor blockade nerve potentials after nociceptive stimulation within the area of sensory block were often able to pass to the cerebral cortex. PMID:3039873

  10. Masculinizing effects on otoacoustic emissions and auditory evoked potentials in women using oral contraceptives.

    PubMed

    McFadden, D

    2000-04-01

    The otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) measured in two separate large scale studies were examined retrospectively for potential differences between those women using, and those not using, oral contraception (OC). Fourteen dependent variables were examined, all of which exhibited substantial sex differences. For 13 of those 14 dependent variables, the means for the users of OC were shifted away from the means of the non-users in the direction of the males. Specifically, for four different measures of OAE strength, for seven of eight measures of AEP latency or amplitude, and for two cognitive tests (mental rotation and water level), the means for the users of OC were located intermediate to those of the non-users of OC and the males. Few of these differences between users and non-users of OC achieved statistical significance, but the near universality of the direction of the difference suggests that oral contraceptives do produce a weak masculinizing effect on some auditory structures. These weak masculinizing effects appear to run contrary to the facts that the levels of both free testosterone and estradiol are lower in women using OC than in normal-cycling women. Past findings on auditory sex differences may have underestimated those sex differences. PMID:10748325

  11. The effect of anaesthesia on somatosensory evoked potential measurement in a rat model.

    PubMed

    Kortelainen, Jukka; Al-Nashash, Hasan; Vipin, Ashwati; Thow, Xin Yuan; All, Angelo

    2016-02-01

    Somatosensory evoked potentials (SEPs) are widely used to study the functional integrity of ascending sensory pathways. For animal studies, SEPs provide a convenient method to quantitatively assess the functionality of the nervous system with low invasiveness. Even though they are frequently used in animal models, little attention is paid to the fact that SEPs are vulnerable to contamination from experimental factors such as anaesthetic delivery. In this study, the effect of isoflurane on SEP measurement was investigated in a rat model. The aim was to find out the adjustments for anaesthetic delivery optimizing the quality of the recordings. Two aspects were studied: the effect of isoflurane dosage on the SEP parameters and on the repeatability of the measurements. The SEP quality was found to be best when 1.5% isoflurane concentration was used. This dosage resulted in the best signal-to-noise ratio and equal repeatability of the measurements compared with the others. Our findings can help in refining the anaesthetic protocols related to SEP recordings in a rat model and, by improving the quality of the measurements, potentially reducing the number of subjects needed to carry out studies. PMID:26025916

  12. Short-duration transient visual evoked potential for objective measurement of refractive errors.

    PubMed

    Anand, Aashish; De Moraes, Carlos Gustavo V; Teng, Christopher C; Liebmann, Jeffrey M; Ritch, Robert; Tello, Celso

    2011-12-01

    This study examined effects of uncorrected refractive errors (RE) in a short-duration transient visual evoked potential (SD t-VEP) system and investigated their role for objective measurement of RE. Refractive errors were induced by means of trial lenses in 35 emmetropic subjects. A synchronized single-channel EEG was recorded for emmetropia, and each simulated refractive state to generate 21 VEP responses for each subject. P100 amplitude (N75 trough to P100 peak) and latency were identified by an automated post-signal processing algorithm. Induced hypermetropia and myopia correlated strongly with both P100 amplitude and latency. To minimize the effect of baseline shift and waveform fluctuations, a VEP scoring system, based on software-derived P100 latency, amplitude and waveform quality, was used to estimate the RE. Using the VEP scores, a single VEP response had a high sensitivity and specificity for discerning emmetropia, small RE (<2 diopter) within a 2 diopter range and large RE (2-14 diopter) within a 4 diopter range. The VEP scoring system has a potential for objective screening of RE and for a more accurate 3-step objective refraction. PMID:21931961

  13. Neurophysiological assessment of perceived image quality using steady-state visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Bosse, Sebastian; Acqualagna, Laura; Porbadnigk, Anne K.; Curio, Gabriel; Müller, Klaus-Robert; Blankertz, Benjamin; Wiegand, Thomas

    2015-09-01

    An approach to the neural measurement of perceived image quality using electroencephalography (EEG) is presented. 6 different images were tested on 6 different distortion levels. The distortions were introduced by a hybrid video encoder. The presented study consists of two parts: In a first part, subjects were asked to evaluate the quality of the test stimuli behaviorally during a conventional psychophysical test using a degradation category rating procedure. In a second part, subjects were presented undistorted and distorted texture images in a periodically alternating fashion at a fixed frequency. This alternating presentation elicits so called steady-state visual evoked potentials (SSVEP) as a brain response that can be measured on the scalp. The amplitude of modulations in the brain signals is significantly and strongly negatively correlated with the magnitude of visual impairment reported by the subjects. This neurophysiological approach to image quality assessment may potentially lead to a more objective evaluation, as behavioral approaches suffer from drawbacks such as biases, inter-subject variances and limitations to test duration.

  14. Visual Evoked Potential Using Head-Mounted Display Versus Cathode Ray Tube: A Pilot Study

    PubMed Central

    Choi, Hyo Seon; Im, Sang Hee; Kim, Yong Kyun

    2016-01-01

    Objective To present a new stimulation method based on the use of a head-mounted display (HMD) during pattern reversal visual evoked potential (PR-VEP) testing and to compare variables of HMD to those of conventional cathode ray tube (CRT). Methods Twenty-three normal subjects without visual problems were recruited. PR-VEPs were generated using CRT or HMD stimuli. VEP outcome measures included latencies (N75, P100, and N145) and peak-to-peak amplitudes (N75–P100 and P100–N145). Subjective discomfort associated with HMD was determined using a self-administered questionnaire. Results PR-VEPs generated by HMD stimuli showed typical triphasic waveforms, the components of which were found to be correlated with those obtained using conventional CRT stimuli. Self-administered discomfort questionnaires revealed that HMD was more comfortable in some aspects. It allowed subjects to concentrate better than CRT. Conclusion The described HMD stimulation can be used as an alternative to the standard CRT stimulation for PR-VEPs. PR-VEP testing using HMD has potential applications in clinical practice and visual system research because HMD can be used on a wider range of subjects compared to CRT. PMID:27152285

  15. Evoked potential correlates of selective attention with multi-channel auditory inputs.

    PubMed

    Schwent, V L; Hillyard, S A

    1975-02-01

    Ten subjects were presented with a random sequence of 50 msec tone pips at a rapid rate (averaging one tone every 225 msec). The tones came from four different sound sources or sensory "channels" each having a different pitch (2000,4000,1000, and 500 c/sec respectively) and perceived spatial position (spaced equidistant across the head). Within each sensory "channel" a random 10% of the tones were of a slightly higher pitch (designated as "targets"). The subject attended to one channel at a time for 7.5 min and counted the targets in that channel. The auditory evoked vertex potential elicited by a channel of stimuli when attended was compared with the mean vertex potential elicited by those same stimuli when the other three channels were being attended. The N1 component (latency 80130 msec) measured re a baseline revealed an increase with attention (82% in the baselineN1 measure, P less than 10-). It was concluded that: (1) this N1 enhancement could not be attributed to peripheral mechanisms acting on sensory transmission; (2) this N1 enhancement reflects a "finely tuned" selective attention to one channel of stimuli among several concurrent and competing channels; and (3) a probable relationship exists between the information load on the subject and the magnitude of this EP enhancement with selective attention. PMID:45943

  16. Comparison of Cervical and Ocular Vestibular Evoked Myogenic Potentials in Dancers and Non-Dancers

    PubMed Central

    Sinha, Sujeet Kumar; Bohra, Vaishnavi; Sanju, Himanshu Kumar

    2013-01-01

    The objective of the study was to assess the sacculocollic and otolith ocular pathway function using cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular myogenic potentials (oVEMP) in dancers and non dancers. Total 16 subjects participated in the study. Out of 16 participants, 8 were trained in Indian classical form of dance (dancers) and other 8 participants who were not trained in any dance form (non dancers). cVEMP and oVEMP responses were recorded for all the subjects. Non Parametric Mann-Whitney U test revealed no significant difference between dancers and non dancers for the latency and amplitude parameter for cVEMP and oVEMP, i.e. P13, N23 latency and P13-N23 complex amplitude and N10, P14 latency, N10-P14 complex amplitude respectively. The vestibular system comprises of several structures. It is possible that the dance style practiced by the dancer’s group assessed in this study does not contribute towards improving the plasticity of the sacculocollic and otolith-ocular pathways. It can be concluded that not all forms of dance training brings about a change in the plasticity of the sacculocollic and otolithocular pathways. PMID:26557344

  17. Contributions of ocular vestibular evoked myogenic potentials and the electrooculogram to periocular potentials produced by whole-body vibration.

    PubMed

    Todd, Neil P M; Bell, Steven L; Paillard, Aurore C; Griffin, Michael J

    2012-11-01

    In this paper we report the results of an experiment to investigate the emergence of ocular vestibular evoked myogenic potentials (OVEMPs) during the linear vestibular ocular reflex (LVOR) evoked by whole-body vibration (WBV). OVEMP and electrooculogram (EOG) montages were employed to record periocular potentials (POPs) from six subjects during WBV in the nasooccipital (NO) axis over a range of frequencies from 0.5 to 64 Hz with approximately constant peak head acceleration of 1.0 ms(-2) (i.e., 0.1 g). Measurements were made in two context conditions: a fixation context to examine the effect of gaze eccentricity (0 vs. 20°), and a visual context, where a target was either head-fixed or earth-fixed. The principal results are that from 0.5 to 2 Hz POP magnitude in the earth-fixed condition is related to head displacement, so with constant acceleration at all frequencies it reduces with increasing frequency, but at frequencies greater than 2 Hz both POP magnitude and POP gain, defined as the ratio of POP magnitude at 20 and 0°, increase with increasing frequency. By exhibiting this high-pass characteristic, a property shared with the LVOR, the results are consistent with the hypothesis that the OVEMP, as commonly employed in the clinical setting, is a high-frequency manifestation of the LVOR. However, we also observed low-frequency acceleration following POPs in head-fixed conditions, consistent with a low-frequency OVEMP, and found evidence of a high-frequency visual context effect, which is also consistent with the OVEMP being a manifestation of the LVOR. PMID:22984251

  18. Contributions of ocular vestibular evoked myogenic potentials and the electrooculogram to periocular potentials produced by whole-body vibration

    PubMed Central

    Bell, Steven L.; Paillard, Aurore C.; Griffin, Michael J.

    2012-01-01

    In this paper we report the results of an experiment to investigate the emergence of ocular vestibular evoked myogenic potentials (OVEMPs) during the linear vestibular ocular reflex (LVOR) evoked by whole-body vibration (WBV). OVEMP and electrooculogram (EOG) montages were employed to record periocular potentials (POPs) from six subjects during WBV in the nasooccipital (NO) axis over a range of frequencies from 0.5 to 64 Hz with approximately constant peak head acceleration of 1.0 ms−2 (i.e., 0.1 g). Measurements were made in two context conditions: a fixation context to examine the effect of gaze eccentricity (0 vs. 20°), and a visual context, where a target was either head-fixed or earth-fixed. The principal results are that from 0.5 to 2 Hz POP magnitude in the earth-fixed condition is related to head displacement, so with constant acceleration at all frequencies it reduces with increasing frequency, but at frequencies greater than 2 Hz both POP magnitude and POP gain, defined as the ratio of POP magnitude at 20 and 0°, increase with increasing frequency. By exhibiting this high-pass characteristic, a property shared with the LVOR, the results are consistent with the hypothesis that the OVEMP, as commonly employed in the clinical setting, is a high-frequency manifestation of the LVOR. However, we also observed low-frequency acceleration following POPs in head-fixed conditions, consistent with a low-frequency OVEMP, and found evidence of a high-frequency visual context effect, which is also consistent with the OVEMP being a manifestation of the LVOR. PMID:22984251

  19. Modeling of region-specific fMRI BOLD neurovascular response functions in rat brain reveals residual differences that correlate with the differences in regional evoked potentials.

    PubMed

    Pawela, Christopher P; Hudetz, Anthony G; Ward, B Douglas; Schulte, Marie L; Li, Rupeng; Kao, Dennis S; Mauck, Matthew C; Cho, Younghoon R; Neitz, Jay; Hyde, James S

    2008-06-01

    The response of the rat visual system to flashes of blue light has been studied by blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). The BOLD temporal response is dependent on the number of flashes presented and demonstrates a refractory period that depends on flash frequency. Activated brain regions included the primary and secondary visual cortex, superior colliculus (SC), dorsal lateral geniculate (DLG), and lateral posterior nucleus (LP), which were found to exhibit differing temporal responses. To explain these differences, the BOLD neurovascular response function was modeled. A second-order differential equation was developed and solved numerically to arrive at region-specific response functions. Included in the model are the light input from the diode (duty cycle), a refractory period, a transient response following onset and cessation of stimulus, and a slow adjustment to changes in the average level of the signal. Constants in the differential equation were evaluated for each region by fitting the model to the experimental BOLD response from a single flash, and the equation was then solved for multiple flashes. The simulation mimics the major features of the data; however, remaining differences in the frequency dependence of the response between the cortical and subcortical regions were unexplained. We hypothesized that these discrepancies were due to regional-specific differences in neuronal response to flash frequency. To test this hypothesis, cortical visual evoked potentials (VEPs) were recorded using the same stimulation protocol as the fMRI. Cortical VEPs were more suppressed than subcortical VEPs as flash frequency increased, supporting our hypothesis. This is the first report that regional differences in neuronal activation to the same stimulus lead to differential BOLD activation. PMID:18406628

  20. Modeling cyclic variations in sustained human performance as measured by reaction time and the flash visual evoked potential-P2.

    PubMed

    Case, Jason L; Arruda, James E; VanWormer, Lisa A

    2016-03-01

    Recent research suggests that sustained attention is punctuated by periodic lapses that produce cyclic variations in sustained human performance. Research conducted by our laboratory (Arruda, Zhang, Amoss, Coburn, & Aue, 2009) and by the laboratories of others (Aue, Arruda, Kass, & Stanny, 2009; Smith, Valentino, & Arruda, 2003) suggests that sustained human performance cycles approximately every 1.5 and 5.2min. Further, it has been suggested that a norepinephrine based arousal system may be responsible for these variations. Unfortunately, both cholinergic and noradrenergic pathways are known to mediate attention and it is unclear from previous research whether one or both of the identified cycles is related to cholinergic functioning. Consequently, the purpose of the present investigation was to assess the validity of the 1.5 and the 5.2mincycles using both reaction time and a cortical marker of cholinergic activity-the flash visual evoked potential P2 (FVEP-P2). Twenty-seven participants performed a 15-min continuous performance task. A spectral analysis procedure was used to detect the prevalence of the 1.5 and 5.2mincycles in both performance and cortical activity. While the results of these analyses support the validity of the 1.5 and 5.2mincycles in sustained human performance, only the 5.2mincycle was detected in cortical activity (i.e., the FVEP-P2 amplitudes) using model fitting. Consequently, the results of the present investigation support the validity of the 1.5 and 5.2mincycles and extend the findings of previous research by implicating acetylcholine in the 5.2mincycle. PMID:26825236

  1. HYPOTHERMIA AND CHLOROPENT ANESTHESIA DIFFERENTIALLY AFFECT THE FLASH EVOKED POTENTIALS OF HOODED RATS

    EPA Science Inventory

    Anesthetics and body temperature alterations are both known to alter parameters of sensory-evoked responses. However few studies have quantitatively assessed the contributions of hypothermia to anesthetic-induced changes. Two experiments were performed. In the first, chronically ...

  2. Cortical motion deafness.

    PubMed

    Ducommun, Christine Y; Michel, Christoph M; Clarke, Stephanie; Adriani, Michela; Seeck, Margitta; Landis, Theodor; Blanke, Olaf

    2004-09-16

    The extent to which the auditory system, like the visual system, processes spatial stimulus characteristics such as location and motion in separate specialized neuronal modules or in one homogeneously distributed network is unresolved. Here we present a patient with a selective deficit for the perception and discrimination of auditory motion following resection of the right anterior temporal lobe and the right posterior superior temporal gyrus (STG). Analysis of stimulus identity and location within the auditory scene remained intact. In addition, intracranial auditory evoked potentials, recorded preoperatively, revealed motion-specific responses selectively over the resected right posterior STG, and electrical cortical stimulation of this region was experienced by the patient as incoming moving sounds. Collectively, these data present a patient with cortical motion deafness, providing evidence that cortical processing of auditory motion is performed in a specialized module within the posterior STG. PMID:15363389

  3. Cortico-cortical communication dynamics

    PubMed Central

    Roland, Per E.; Hilgetag, Claus C.; Deco, Gustavo

    2014-01-01

    In principle, cortico-cortical communication dynamics is simple: neurons in one cortical area communicate by sending action potentials that release glutamate and excite their target neurons in other cortical areas. In practice, knowledge about cortico-cortical communication dynamics is minute. One reason is that no current technique can capture the fast spatio-temporal cortico-cortical evolution of action potential transmission and membrane conductances with sufficient spatial resolution. A combination of optogenetics and monosynaptic tracing with virus can reveal the spatio-temporal cortico-cortical dynamics of specific neurons and their targets, but does not reveal how the dynamics evolves under natural conditions. Spontaneous ongoing action potentials also spread across cortical areas and are difficult to separate from structured evoked and intrinsic brain activity such as thinking. At a certain state of evolution, the dynamics may engage larger populations of neurons to drive the brain to decisions, percepts and behaviors. For example, successfully evolving dynamics to sensory transients can appear at the mesoscopic scale revealing how the transient is perceived. As a consequence of these methodological and conceptual difficulties, studies in this field comprise a wide range of computational models, large-scale measurements (e.g., by MEG, EEG), and a combination of invasive measurements in animal experiments. Further obstacles and challenges of studying cortico-cortical communication dynamics are outlined in this critical review. PMID:24847217

  4. Potentiation of K+-evoked catecholamine release in the cat adrenal gland treated with ouabain.

    PubMed Central

    Garcia, A. G.; Garcia-Lopez, E.; Horga, J. F.; Kirpekar, S. M.; Montiel, C.; Sanchez-Garcia, P.

    1981-01-01

    1 A vigorous catecholamine secretory response was evoked by small increments (2-10 mM) of the extracellular concentration of K+ ([K+])o) in cat adrenal glands treated with ouabain (10(-4) M), and perfused with Krebs-bicarbonate solution at room temperature. 2 The secretory response depends on [K+]o; increments of [K+]o as small as 2 mM for 2 min evoked a clear secretory response; at 10-17.7 mM K+, the maximal secretory response was observed. In normal glands, not treated with ouabain, no increase of the rate of catecholamine output was observed by raising [K+]o up to 17.7 mM for 2 min. 3 The K+ secretory response was time-dependent, requiring at least 1 min to be initiated; on continued exposure to 10 mM [K+]o, the enhanced response remained for at least 1 h. 4 In low [Na+]o, the K+-secretory response was unchanged. However, in 0-Ca2+, high-Mg2+ solutions, or in the presence of D600, an organic Ca2+ antagonist, it was abolished. 5 The K+-induced secretory response was not altered in the presence of tetrodoxin or tetraethylammonium. 6 It is concluded that ouabain potentiated the catecholamine secretory response to raised [K+]o by increasing the amount of Ca2+ available to the secretory machinery through (a) mobilization of an enhanced pool of membrane-bound Ca2+, (b) activation of membrane Ca2+ inward current; or (c) decrease of intracellular Ca2+ buffering systems. The activation by ouabain of a membrane Na+-Ca2+ exchange system is not involved in this K+-secretory response. It is suggested that the plasma membrane ATPase enzyme system, by changing the affinity of its Ca2+ binding sites, might control the availability of this cation to the secretory machinery and, therefore, modulate catecholamine secretion in the adrenal gland. PMID:7296168

  5. Attachment style moderates partner presence effects on pain: a laser-evoked potentials study.

    PubMed

    Krahé, Charlotte; Paloyelis, Yannis; Condon, Heather; Jenkinson, Paul M; Williams, Steven C R; Fotopoulou, Aikaterini

    2015-08-01

    Social support is crucial for psychological and physical well-being. Yet, in experimental and clinical pain research, the presence of others has been found to both attenuate and intensify pain. To investigate the factors underlying these mixed effects, we administered noxious laser stimuli to 39 healthy women while their romantic partner was present or absent, and measured pain ratings and laser-evoked potentials (LEPs) to assess the effects of partner presence on subjective pain experience and underlying neural processes. Further, we examined whether individual differences in adult attachment style (AAS), alone or in interaction with the partner's level of attentional focus (manipulated to be either on or away from the participant) might modulate these effects. We found that the effects of partner presence vs absence on pain-related measures depended on AAS but not partner attentional focus. The higher participants' attachment avoidance, the higher pain ratings and N2 and P2 local peak amplitudes were in the presence compared with the absence of the romantic partner. As LEPs are thought to reflect activity relating to the salience of events, our data suggest that partner presence may influence the perceived salience of events threatening the body, particularly in individuals who tend to mistrust others. PMID:25556212

  6. Human high frequency somatosensory evoked potential components are refractory to circadian modulations of tonic alertness.

    PubMed

    Gobbelé, René; Waberski, Till D; Thyerlei, Dinah; Thissen, Melanie; Fimm, Bruno; Klostermann, Fabian; Curio, Gabriel; Buchner, Helmut

    2007-02-01

    The impact of vigilance states, such as sleep or arousal changes, on the high-frequency (600 Hz) components (HFOs) of somatosensory evoked potentials (SEPs) is known. The present study sought to characterize the effects of circadian fluctuations of tonic alertness on HFOs in awake humans. Median nerve SEPs were recorded at four times during a 24-hour waking period. In parallel to the SEP recordings, a reaction-time (RT) task was performed to assess tonic alertness. Additionally, the spontaneous EEG was monitored. The low-frequency SEP component N20 and the early and late HFO parts did not change across the measurement sessions. In contrast, RTs were clearly prolonged at night and on the second morning. EEG also showed increased delta power at night. HFOs are sensitive to pronounced vigilance changes, such as sleep, but are refractory to fluctuations of tonic alertness. Tonic alertness is regarded to be the top-down cognitive control mechanism of wakefulness, whereas sleep is mediated by overwhelming bottom-up regulation, which seems apparently more relevant for, at least in part, subcortically triggered high-frequency burst generation in the ascending somatosensory system. PMID:17277574

  7. 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

  8. Transcranial Motor Evoked Potentials of Lower Limbs Can Prognosticate Ambulation in Hemiplegic Stroke Patients

    PubMed Central

    2016-01-01

    Objective To examine the association between motor evoked potentials (MEPs) in lower limbs and ambulatory outcomes of hemiplegic stroke patients. Methods Medical records of hemiplegic patients with the first ever stroke who received inpatient rehabilitation from January 2013 to May 2014 were reviewed. Patient who had diabetes, quadriplegia, bilateral lesion, brainstem lesion, severe musculoskeletal problem, and old age over 80 years were excluded. MEPs in lower limbs were measured when they were transferred to the Department of Rehabilitation Medicine. Subjects were categorized into three groups (normal, abnormal, and absent response) according to MEPs findings. Berg Balance Scale (BBS) and Functional Ambulation Category (FAC) at initial and discharge were compared among the three groups by one-way analysis of variance (ANOVA). Correlation was determined using a linear regression model. Results Fifty-eight hemiplegic patients were included. BBS and FAC at discharge were significantly (ANOVA, p<0.001) different according to MEPs findings. In linear regression model of BBS and FAC using stepwise selection, patients' age (p<0.01), BBS at admission (p<0.01), and MEPs (p<0.01) remained significant covariates. In regression assumption model of BBS and FAC at admission, MEPs and gender were significant covariates. Conclusion Initial MEPs of lower limbs can prognosticate the ambulatory outcomes of hemiplegic patients. PMID:27446774

  9. Ketamine-Based Anesthetic Protocols and Evoked Potential Monitoring: A Risk/Benefit Overview.

    PubMed

    Stoicea, Nicoleta; Versteeg, Gregory; Florescu, Diana; Joseph, Nicholas; Fiorda-Diaz, Juan; Navarrete, Víctor; Bergese, Sergio D

    2016-01-01

    Since its discovery, ketamine, a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist related to phencyclidine, has been linked to multiple adverse reactions sometimes described as "out of body" and "near death experiences," including emergence phenomena, delusions, hallucinations, delirium, and confusion. Due to these effects, ketamine has been withdrawn from mainstream anesthetic use in adult patients. Evoked potentials (EPs) are utilized to monitor neural pathways during surgery, detect intraoperative stress or damage, detect and define the level of neural lesions, and define abnormalities. Unfortunately, many of the volatile anesthetics commonly used during spinal and neurologic procedures suppress EP amplitude and monitoring. Ketamine has been found in several preclinical and clinical studies to actually increase EP amplitude and thus has been used as an analgesic adjunct in procedures where EP monitoring is critical. Once the gap in our knowledge of ketamine's risks has been sufficiently addressed in animal models, informed clinical trials should be conducted in order to properly incorporate ketamine-based anesthetic regimens during EP-monitored neurosurgeries. PMID:26909017

  10. Distortion product otoacoustic emissions and auditory evoked potentials in the hedgehog tenrec, Echinops telfairi.

    PubMed

    Drexl, Markus; Faulstich, Michael; Von Stebut, Boris; Radtke-Schuller, Susanne; Kössl, Manfred

    2003-12-01

    The hedgehog tenrec, Echinops telfairi, has certain basal mammalian features, like a cloaca and a sparsely differentiated brain with smooth cerebral hemispheres. The peripheral auditory capabilities of this species were investigated by means of distortion product otoacoustic emissions (DPOAE). For comparison, we determined auditory evoked potentials (AEP) in the inferior colliculus and the auditory cortex. Both methods show that the auditory range of E. telfairi extends well into ultrasonic frequencies, with a region of highest sensitivity at around 16 kHz. The total auditory range spans about 4 octaves at 40 dB SPL. The low-frequency limit of auditory processing is found at frequencies of about 2-3 kHz. The DPOAE and the AEP thresholds of E. telfairi do not run fully parallel in the high-frequency range. For a threshold value of 40 dB SPL, cochlear mechanical thresholds as measured with DPOAE extend up to 50 kHz, whereas neuronal thresholds reach the high-frequency limit at about 30 kHz. Frequency tuning, as assessed from DPOAE suppression tuning curves, was low to moderate with Q(10 dB) values ranging from 1.7 to 8. The lack of discontinuity in the group delay (derived from DPOAE measurements) reveals that cochlear frequency representation is tonotopic without any region of specialized mechanical tuning. PMID:14569428

  11. Stimulus Specificity of Brain-Computer Interfaces Based on Code Modulation Visual Evoked Potentials

    PubMed Central

    Wei, Qingguo; Feng, Siwei; Lu, Zongwu

    2016-01-01

    A brain-computer interface (BCI) based on code modulated visual evoked potentials (c-VEP) is among the fastest BCIs that have ever been reported, but it has not yet been given a thorough study. In this study, a pseudorandom binary M sequence and its time lag sequences are utilized for modulation of different stimuli and template matching is adopted as the method for target recognition. Five experiments were devised to investigate the effect of stimulus specificity on target recognition and we made an effort to find the optimal stimulus parameters for size, color and proximity of the stimuli, length of modulation sequence and its lag between two adjacent stimuli. By changing the values of these parameters and measuring classification accuracy of the c-VEP BCI, an optimal value of each parameter can be attained. Experimental results of ten subjects showed that stimulus size of visual angle 3.8°, white, spatial proximity of visual angle 4.8° center to center apart, modulation sequence of length 63 bits and the lag