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Sample records for cortical evoked potentials

  1. Cortical evoked potentials recorded from the guinea pig without averaging.

    PubMed

    Walloch, R A

    1975-01-01

    Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.

  2. 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…

  3. Cortically evoked potentials in the human subthalamic nucleus.

    PubMed

    Zwartjes, Daphne G M; Janssen, Marcus L F; Heida, Tjitske; Van Kranen-Mastenbroek, Vivianne; Bour, Lo J; Temel, Yasin; Visser-Vandewalle, Veerle; Veltink, Peter H

    2013-02-28

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in Parkinson's disease (PD) patients. However, in a substantial number of patients the beneficial effects of STN DBS are overshadowed by psychiatric side effects. We hypothesize that stimulation of the STN motor area will provide the optimal effect on the motor symptoms without inducing these side effects, and expect that motor cortex stimulation (MCS) evokes a spatially specific response within the STN, which identifies the STN motor area. We previously showed that MCS evokes responses in the unit activity specifically within certain areas of the STN. Unit activity is generally considered a measure of the output activity. To gain more insight into the neuronal input into the STN, we describe the results of cortically evoked subthalamic local field potentials (LFPs). We show that the cortically evoked LFPs follow a certain temporal and spatial pattern. The significant peaks of the evoked LFPs coincide with the timing of some of the inhibitions and excitations present in the unit responses. The spatial resolution of responses measured in the LFP to MCS is not high enough to identify the STN motor region. However, we believe that optimizing targeting techniques and the development of novel DBS electrodes will improve STN DBS therapy for PD patients.

  4. 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

  5. [Experimental visual evoked potentials. Interstimuli interval and cortical excitability].

    PubMed

    Díaz Calavia, E; Fernández del Moral, R; Dawid-Milner, S; Jiménez Vargas, J

    1989-01-01

    The excitability of the visual system was studied in ten adult chronic cats. Visual evoked potentials were recorded, using decreasing interstimulus intervals. A decrease of the excitability of the visual system is observed when interstimulus intervals are less than 800 milliseconds. Clinical applications with regard to visual evoked potential recording on comatose patients are suggested.

  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. Predicting perception in noise using cortical auditory evoked potentials.

    PubMed

    Billings, Curtis J; McMillan, Garnett P; Penman, Tina M; Gille, Sun Mi

    2013-12-01

    Speech perception in background noise is a common challenge across individuals and health conditions (e.g., hearing impairment, aging, etc.). Both behavioral and physiological measures have been used to understand the important factors that contribute to perception-in-noise abilities. The addition of a physiological measure provides additional information about signal-in-noise encoding in the auditory system and may be useful in clarifying some of the variability in perception-in-noise abilities across individuals. Fifteen young normal-hearing individuals were tested using both electrophysiology and behavioral methods as a means to determine (1) the effects of signal-to-noise ratio (SNR) and signal level and (2) how well cortical auditory evoked potentials (CAEPs) can predict perception in noise. Three correlation/regression approaches were used to determine how well CAEPs predicted behavior. Main effects of SNR were found for both electrophysiology and speech perception measures, while signal level effects were found generally only for speech testing. These results demonstrate that when signals are presented in noise, sensitivity to SNR cues obscures any encoding of signal level cues. Electrophysiology and behavioral measures were strongly correlated. The best physiological predictors (e.g., latency, amplitude, and area of CAEP waves) of behavior (SNR at which 50 % of the sentence is understood) were N1 latency and N1 amplitude measures. In addition, behavior was best predicted by the 70-dB signal/5-dB SNR CAEP condition. It will be important in future studies to determine the relationship of electrophysiology and behavior in populations who experience difficulty understanding speech in noise such as those with hearing impairment or age-related deficits.

  8. 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.

  9. An observation on flash evoked cortical potentials and Qigong meditation.

    PubMed

    Zhang, W; Zheng, R; Zhang, B; Yu, W; Shen, X

    1993-01-01

    The purpose of this study was to investigate the functional state of the cerebral cortex during Qigong meditation with flash visual evoked potentials (F-VEPs) recorded from the occipital scalp in four groups of adults. The first group included 14 subjects who had exercised in Neiyang Gong for 0.5-5.5 years. The second group was composed of 12 subjects who had practiced Neiyang Gong for only 0.5-3 months. Eleven subjects who had never practiced Qigong before made up the third group and served as control. Eleven Qigong practitioners constituted the fourth group. It was found that F-VEP amplitudes were increased in the first group and decreased in the fourth group with the exception of one subject during Qigong meditation. No significant changes were found in the second group and controls. The results were discussed and it is shown that Qigong mediation may have either facilitative or inhibitory effects on the visual cortex depending on the Qigong methods practiced by different individuals.

  10. [In vivo investigation of human brain networks by using cortico-cortical evoked potentials].

    PubMed

    Matsumoto, Riki; Kunieda, Takeharu; Ikeda, Akio

    2012-09-01

    A better understanding of seizure networks and the mechanisms underlying human higher cortical functions requires a detailed knowledge of neuronal connectivity. As it relates to higher cortical functions, such as language, in humans, studies performed in nonhuman primates are less relevant. By using subdural electrodes implanted for presurgical evaluation, we developed an in vivo electrical tract-tracing technique of cortico-cortical evoked potentials (CCEPs). Cortico-cortical connections could be traced by applying repetitive single-pulse electrical stimuli to a part of the cortices and recording evoked cortical potentials from adjacent and remote cortical regions by averaging electrocorticogram time-locked to stimulus onset. This technique has contributed to the understanding of human cortico-cortical networks involved in higher brain functions, such as language, praxis, and higher motor control. Establishing a CCEP connectivity map in the MNI standard space is also of academic importance, since a standardized CCEP connectivity map would provide a substantial reference for noninvasive network analyses. In addition to its importance in basic systems neuroscience, this method, in combination with conventional cortical mapping, could be used to clinically map functional brain systems by tracking cortico-cortical connections among functional cortical regions in individual patients. This approach may help identify the cortico-cortical network of a given function within the context of pathology and any resultant plasticity of brain systems. In relation to epileptogenicity, as CCEPs can be used as a measure of regional cortical excitability, stimulating the epileptic focus and recording CCEPs in adjacent areas could help evaluate cortical excitability at and around the focus.

  11. 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

  12. Effects of Consonant-Vowel Transitions in Speech Stimuli on Cortical Auditory Evoked Potentials in Adults

    PubMed Central

    Doellinger, Michael; Burger, Martin; Hoppe, Ulrich; Bosco, Enrico; Eysholdt, Ulrich

    2011-01-01

    We examined the neural activation to consonant-vowel transitions by cortical auditory evoked potentials (AEPs). The aim was to show whether cortical response patterns to speech stimuli contain components due to one of the temporal features, the voice-onset time (VOT). In seven normal-hearing adults, the cortical responses to four different monosyllabic words were opposed to the cortical responses to noise stimuli with the same temporal envelope as the speech stimuli. Significant hemispheric asymmetries were found for speech but not in noise evoked potentials. The difference signals between the AEPs to speech and corresponding noise stimuli revealed a significant negative component, which correlated with the VOT. The hemispheric asymmetries can be referred to rapid spectral changes. The correlation with the VOT indicates that the significant component in the difference signal reflects the perception of the acoustic change within the consonant-vowel transition. Thus, at the level of automatic processing, the characteristics of speech evoked potentials appear to be determined primarily by temporal aspects of the eliciting stimuli. PMID:21643536

  13. 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

  14. Cerebral cortical respiratory-related evoked potentials elicited by inspiratory occlusion in lambs.

    PubMed

    Davenport, Paul W; Hutchison, Alastair A

    2002-07-01

    Respiratory-related evoked potentials (RREP) elicited by inspiratory mechanical loads have been recorded in humans. Early RREP peaks were hypothesized to be generated by activation of neurons in the somatosensory cortex. An animal model was developed to test this hypothesis in chronically instrumented, awake, spontaneously breathing lambs. Electrocorticogram (ECoG) was recorded bilaterally with ball electrodes on the dural surface over the somatosensory region. Inspiratory occlusions were presented through a face mask or endotracheal tube as interruptions of inspiration. Occlusion-elicited evoked potentials were obtained by computer-signal averaging the ECoG activity. A short-latency positive peak was observed bilaterally in the averaged occlusion-elicited evoked potentials in all animals breathing with the facemask and 5 of 8 lambs with the endotracheal tube. Postmortem identification of the electrode location demonstrated that the ECoG was recorded in the caudal-lateral portion of the somatosensory cortex. These results demonstrate that inspiratory occlusion elicits an evoked potential in the somatosensory cortical region of awake, spontaneously breathing lambs. The lamb cortical RREP is similar to human RREP.

  15. 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

  16. 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.

  17. Spatiotemporal analysis of the cortical sources of the steady-state visual evoked potential.

    PubMed

    Di Russo, Francesco; Pitzalis, Sabrina; Aprile, Teresa; Spitoni, Grazia; Patria, Fabiana; Stella, Alessandra; Spinelli, Donatella; Hillyard, Steven A

    2007-04-01

    This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874-886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing.

  18. 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.

  19. 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

  20. 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

  1. Cerebral hypoxia, missing cortical somatosensory evoked potentials and recovery of consciousness

    PubMed Central

    2014-01-01

    Background Bilaterally absent N20 components of the sensory evoked potentials (SEP) from the median nerve are regarded as accurately predicting poor outcome after cardiac arrest. Case presentation We are reporting on a patient, who regained consciousness despite this ominous finding. Early after cardiac arrest, MRI showed signal alterations in diffusion weighted imaging (DWI) bilaterally in the primary visual and sensorimotor cortex and in the basal ganglia. SEP were repeatedly absent. The patient survived shut out form sensory and visual experience and locked in for voluntary movements, but kept her verbal competence in several languages. Conclusion SEP inform about integrity only of a narrow cortical strip. It is unguarded, but common practice, to conclude from absent SEP, that a patient has suffered diffuse cortical damage after cardiac arrest. Cerebral MRI with DWI helps to avoid this prognostic error and furthers understanding of the sometimes very peculiar state of mind after cardiac arrest. PMID:24720818

  2. The locus of color sensation: cortical color loss and the chromatic visual evoked potential.

    PubMed

    Crognale, Michael A; Duncan, Chad S; Shoenhard, Hannah; Peterson, Dwight J; Berryhill, Marian E

    2013-01-01

    Color losses of central origin (cerebral achromatopsia and dyschromatopsia) can result from cortical damage and are most commonly associated with stroke. Such cases have the potential to provide useful information regarding the loci of the generation of the percept of color. One available tool to examine this issue is the chromatic visual evoked potential (cVEP). The cVEP has been used successfully to objectively quantify losses in color vision capacity in both congenital and acquired deficiencies of retinal origin but has not yet been applied to cases of color losses of cortical origin. In addition, it is not known with certainty which cortical sites are responsible for the generation of the cVEP waveform components. Here we report psychophysical and electrophysiological examination of a patient with color deficits resulting from a bilateral cerebral infarct in the ventral occipitotemporal region. Although this patient demonstrated pronounced color losses of a general nature, the waveform of the cVEP remains unaffected. Contrast response functions of the cVEP are also normal for this patient. The results suggest that the percept of color arises after the origin of the cVEP and that normal activity in those areas that give rise to the characteristic negative wave of the cVEP are not sufficient to provide for the normal sensation of color. PMID:23986535

  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.

  4. 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

  5. Functional connectivity in the human language system: a cortico-cortical evoked potential study.

    PubMed

    Matsumoto, Riki; Nair, Dileep R; LaPresto, Eric; Najm, Imad; Bingaman, William; Shibasaki, Hiroshi; Lüders, Hans O

    2004-10-01

    A better understanding of the mechanisms involved in human higher cortical functions requires a detailed knowledge of neuronal connectivity between functional cortical regions. Currently no good method for tracking in vivo neuronal connectivity exists. We investigated the inter-areal connections in vivo in the human language system using a new method, which we termed 'cortico-cortical evoked potentials' (CCEPs). Eight patients with epilepsy (age 13-42 years) underwent invasive monitoring with subdural electrodes for epilepsy surgery. Six patients had language dominance on the side of grid implantation and two had bilateral language representation by the intracarotid amobarbital test. Conventional cortical electrical stimulation was performed to identify the anterior and posterior language areas. Single pulse electrical stimuli were delivered to the anterior language (eight patients), posterior language (four patients) or face motor (two patients) area, and CCEPs were obtained by averaging electrocorticograms (ECoGs) recorded from the perisylvian and extrasylvian basal temporal language areas time-locked to the stimulus. The subjects were not asked to perform any tasks during the study. Stimulation at the anterior language area elicited CCEPs in the lateral temporo-parietal area (seven of eight patients) in the middle and posterior part of the superior temporal gyrus, the adjacent part of the middle temporal gyrus and the supramarginal gyrus. CCEPs were recorded in 3-21 electrodes per patient. CCEPs occurred at or around the particular electrodes in the posterior language area which, when stimulated, produced speech arrest. Similar early and late CCEPs were obtained from the basal temporal area by stimulating the anterior language area (three of three patients). In contrast, stimulation of the adjacent face motor area did not elicit CCEPs in language areas but rather in the postcentral gyrus. Stimulation of the posterior language area produced CCEPs in the anterior

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

    PubMed

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

    2014-12-01

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

  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.

  8. 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

  9. 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.

  10. Dynamics of Infant Cortical Auditory Evoked Potentials (CAEPs) for Tone and Speech Tokens

    PubMed Central

    Cone, Barbara; Whitaker, Richard

    2013-01-01

    Objectives Cortical auditory evoked potentials (CAEPs) to tones and speech sounds were obtained in infants to: 1) further knowledge of auditory development above the level of the brainstem during the first year of life; 2) establish CAEP input-output functions for tonal and speech stimuli as a function of stimulus level and to 3) elaborate the data-base that establishes CAEP in infants tested while awake using clinically relevant stimuli, thus providing methodology that would have translation to pediatric audiological assessment. Hypotheses concerning CAEP development were that the latency and amplitude input-output functions would reflect immaturity in encoding stimulus level. In a second experiment, infants were tested with the same stimuli used to evoke the CAEPs. Thresholds for these stimuli were determined using observer-based psychophysical techniques. The hypothesis was that the behavioral thresholds would be correlated with CAEP input-output functions because of shared cortical response areas known to be active in sound detection. Design 36 infants, between the ages of 4-12 months (mean= 8 months, s.d.=1.8 months) and 9 young adults (mean age 21 years) with normal hearing were tested. First, CAEPs amplitude and latency input-output functions were obtained for 4 tone bursts and 7 speech tokens. The tone bursts stimuli were 50 ms tokens of pure tones at 0.5, 1.0, 2.0 and 4.0 kHz. The speech sound tokens, /a/, /i/, /o/, /u/, /m/, /s/, and /∫/, were created from natural speech samples and were also 50 ms in duration. CAEPs were obtained for tone burst and speech token stimuli at 10 dB level decrements in descending order from 70 dB SPL. All CAEP tests were completed while the infants were awake and engaged in quiet play. For the second experiment, observer-based psychophysical methods were used to establish perceptual threshold for the same speech sound and tone tokens. Results Infant CAEP component latencies were prolonged by 100-150 ms in comparison to

  11. 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

  12. 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

  13. 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

  14. Cortical configuration by stimulus onset visual evoked potentials (SO-VEPs) predicts performance on a motion direction discrimination task.

    PubMed

    Zalar, Bojan; Martin, Tim; Kavcic, Voyko

    2015-06-01

    The slowing of information processing, a hallmark of cognitive aging, has several origins. Previously we reported that in a motion direction discrimination task, older as compared to younger participants showed prolonged non-decision time, an index of an early perceptual stage, while in motion onset visual evoked potentials (MO-VEPs) the P1 component was enhanced and N2 was diminished. We did not find any significant correlations between behavioral and MO-VEP measures. Here, we investigated the role of age in encoding and perceptual processing of stimulus onset visually evoked potentials (SO-VEPs). Twelve healthy adults (age<55years) and 19 elderly (age>55years) performed a motion direction discrimination task during EEG recording. Prior to motion, the stimulus consisted of a static cloud of white dots on a black background. As expected, SO-VEPs evoked well defined P1, N1, and P2 components. Elderly participants as compared to young participants showed increased P1 amplitude while their P2 amplitude was reduced. In addition elderly participants showed increased latencies for P1 and N1 components. Contrary to the findings with MO-VEPs, SO-VEP parameters were significant predictors of average response times and diffusion model parameters. Our electrophysiological results support the notion that slowing of information processing in older adults starts at the very beginning of encoding in visual cortical processing, most likely in striate and extrastriate visual cortices. More importantly, the earliest SO-VEP components, possibly reflecting configuration of visual cortices and encoding processes, predict subsequent prolonging and tardiness of perceptual and higher-level cognitive processes.

  15. Short-latency cortical potentials evoked by tactile air-jet stimulation of body and face in man.

    PubMed

    Schieppati, M; Ducati, A

    1984-11-01

    Natural cutaneous stimulation was performed in 10 healthy volunteers by means of a brief, localized air jet directed to the glabrous skin of the face, finger or toe. Neurograms (from finger stimulation) and somatosensory evoked potentials (SEPs) were recorded and, in the case of finger and toe stimulation, compared with the SEPs obtained by low intensity electrical stimulation. Comparing the latencies at wrist and elbow of the respective neurograms, it appears that a 2 msec period accounts for skin indentation and build-up of the generator potential in the receptors activated by the air jet. A slightly lower conduction velocity was obtained on natural than on electrical stimulation, and the cortical SEPs accordingly had a longer latency. In spite of the much smaller amplitude of the air-jet evoked neurograms, the amplitudes of the SEPs from finger and toe were similar to the amplitudes of the SEPs on electrical stimulation of the same regions. Natural stimulation in the regions innervated by the 3 branches of the trigeminal nerve (tongue included) yielded consistent SEPs, comparable with those reported in the literature to electrical stimulation. These potentials were distinguishable from the electrical activity due to the blink reflex, which invariably takes place on air-jet stimulation of the first trigeminal branch.

  16. Repetition suppression in the cortical motor and auditory systems resemble each other--a combined TMS and evoked potential study.

    PubMed

    Löfberg, O; Julkunen, P; Tiihonen, P; Pääkkönen, A; Karhu, J

    2013-07-23

    Repetition suppression (RS) in cortical sensory systems optimizes the size of neuronal ensemble reacting to repetitive stimuli such as sounds. Recently RS has also been demonstrated to occur with mental imaging of movement. We studied the existence of RS in the motor system using transcranial magnetic stimulation (TMS). Six healthy subjects participated in this study. TMS was focused on the primary motor cortex with neuronavigation and RS was studied by measuring the motor-evoked potentials from the contralateral first dorsal interosseous muscle. At the same time, we measured TMS-induced cortical responses using electroencephalography (EEG). For a comparison baseline, we evaluated RS by recording EEG responses to sounds with the same stimulation protocol as with TMS. Each stimulus train included four identical stimuli repeated at 1-s intervals, and the stimulation trains were repeated at 20-s intervals. The response amplitude was reduced significantly (p<.01) after the first stimulus in all stimulus trains. This suggests that RS may be a general mechanism for adaptation of neuronal population responses in the human cortex.

  17. 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

  18. Evaluation of combined use of transcranial and direct cortical motor evoked potential monitoring during unruptured aneurysm surgery.

    PubMed

    Motoyama, Yasushi; Kawaguchi, Masahiko; Yamada, Shuichi; Nakagawa, Ichiro; Nishimura, Fumihiko; Hironaka, Yasuo; Park, Young-Su; Hayashi, Hironobu; Abe, Ryuichi; Nakase, Hiroyuki

    2011-01-01

    The feasibility and reliability of combined use of transcranial and direct cortical motor evoked potential (MEP) monitoring during unruptured aneurysm surgery were evaluated. Forty-eight patients with unruptured cerebral aneurysms underwent craniotomy and neck clipping accompanied by muscle MEP monitoring. MEPs were elicited successfully by transcranial electrical stimulation in all patients. Direct cortical stimulation elicited MEPs in 44 patients. Reduction in MEP amplitude to less than 50% of baseline was considered significant. No postoperative motor paresis occurred in 39 patients in whom transcranial and direct MEPs remained unchanged. Four patients in whom direct MEPs could not be recorded had no intraoperative abnormality in transcranial MEPs and no postoperative motor dysfunction. Four of the other 5 patients manifested significant transient direct MEP changes without transcranial MEP changes. The transient MEP changes were observed in 3 patients during temporary clipping of the parent artery and in one patient with inadequate clipping of an middle cerebral artery aneurysm, and were considered due to insufficiency of blood flow. Decrease or disappearance of direct MEP waves recovered immediately after re-application of the clip and release of the temporary clip. Direct MEP waves disappeared and did not recover until the end of microsurgical procedures in one patient, although transcranial MEP amplitude remained at less than 50% of baseline. She developed hemiparesis postoperatively, which recovered within 6 hours. The duration of temporary occlusion in patients with direct MEP changes was significantly longer than that in patients without (p < 0.05). Direct MEP was sensitive in detecting ischemic stress to descending motor pathways during aneurysm surgery. Transcranial MEPs could be elicited in patients in whom direct MEPs could not be obtained, and during periods such as craniotomy or after dural closure, in which direct MEPs could not be recorded. These

  19. [Evoked potentials and inhalation anesthetics].

    PubMed

    Thiel, A; Russ, W; Hempelmann, G

    1988-01-01

    Intraoperative monitoring of evoked potentials can be affected by various factors including volatile anaesthetics. These effects have to be considered in order to give correct interpretations of the obtained data. Visual evoked potentials (VEP) and auditory evoked potentials (AEP) will show strong alterations under general anaesthesia whereas brainstem auditory evoked potentials (BAEP) are slightly affected. The effects of nitrous oxide, halothane, enflurane, and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 35 healthy adult patients. pCO2 and tympanic membrane temperature were held constant. Simultaneous cervical and cortical SEP recording was performed using surface electrodes. After induction of anaesthesia SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. 10 patients received halothane at inspired concentrations of 0.5, 1.0, 1.5, and 2.0%. After nitrous oxide had been replaced by oxygen, halothane was reduced in steps of 0.5%. SEP were recorded at the end of each period (15 min). Equipotent doses of enflurane or isoflurane were administered to 15 and 10 patients, respectively. Nitrous oxide depressed early cortical SEP amplitude. Halothane, enflurane, and isoflurane caused dose dependent increases of latencies. Reduction of amplitude was most pronounced with isoflurane. Using high doses of enflurane in oxygen cortical SEP showed unusual high amplitudes associated with marked increases of latencies. Even under high concentrations of volatile anaesthetics cervical SEP were minimally affected. The effects of anaesthetic gases have to be considered when SEP are recorded intraoperatively.

  20. Sensitivity of cortical auditory evoked potential detection for hearing-impaired infants in response to short speech sounds

    PubMed Central

    Van Dun, Bram; Carter, Lyndal; Dillon, Harvey

    2012-01-01

    Cortical auditory evoked potentials (CAEPs) are an emerging tool for hearing aid fitting evaluation in young children who cannot provide reliable behavioral feedback. It is therefore useful to determine the relationship between the sensation level of speech sounds and the detection sensitivity of CAEPs, which is the ratio between the number of detections and the sum of detections and non-detections. Twenty-five sensorineurally hearing impaired infants with an age range of 8 to 30 months were tested once, 18 aided and 7 unaided. First, behavioral thresholds of speech stimuli /m/, /g/, and /t/ were determined using visual reinforcement orientation audiometry. Afterwards, the same speech stimuli were presented at 55, 65, and 75 dB sound pressure level, and CAEPs were recorded. An automatic statistical detection paradigm was used for CAEP detection. For sensation levels above 0, 10, and 20 dB respectively, detection sensitivities were equal to 72±10, 75±10, and 78±12%. In 79% of the cases, automatic detection P-values became smaller when the sensation level was increased by 10 dB. The results of this study suggest that the presence or absence of CAEPs can provide some indication of the audibility of a speech sound for infants with sensorineural hearing loss. The detection of a CAEP might provide confidence, to a degree commensurate with the detection probability, that the infant is detecting that sound at the level presented. When testing infants where the audibility of speech sounds has not been established behaviorally, the lack of a cortical response indicates the possibility, but by no means a certainty, that the sensation level is 10 dB or less. PMID:26557328

  1. 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

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

    PubMed

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

    2013-01-01

    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 70 μm 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 2-20 Hz, 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

  3. 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

  4. 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…

  5. 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.

  6. 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

    2016-04-19

    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.

  7. 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

  8. Motor neuron disease with pyramidal tract dysfunction involves the cortical generators of the early somatosensory evoked potential to tibial nerve stimulation.

    PubMed

    Zanette, G; Tinazzi, M; Polo, A; Rizzuto, N

    1996-10-01

    We evaluated somatosensory evoked potentials (SEPs) to tibial nerve stimulation in 39 patients with sporadic motor neuron disease using multiple scalp derivations (earlobe reference). SEPs were altered in 22 of 29 amyotrophic lateral sclerosis (ALS) patients, whereas they were unaffected in 10 progressive muscular atrophy (PMA) patients. The main changes involved the amplitude and the field distribution of the early P40 and N37 cortical potentials with different modalities varying from a selective loss of the P40 potential (33% of tested sides) to absence of all early cortical SEPs (22% of tested sides). The later components following N50 were generally spared. The commonly used Cz-Fz montage was inadequate for detecting these alterations. Central afferent conduction was slightly affected. The selective loss of cortical SEPs and their close correlation with clinicoelectrophysiologic evidence of central motor system involvement strongly support a cortical origin of the SEP alterations in ALS. We suggest that neuronal loss in the somatosensory cortex may selectively affect the generator sites of the cortical SEPs to lower limb stimulation. PMID:8857722

  9. 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

  10. [The effect of millimeter-range electromagnetic radiation on the evoked potentials from the vestibular cortical area of the cerebral hemispheres (an experimental study)].

    PubMed

    Mal'tsev, A E; Abakarov, A T

    1994-01-01

    Acute experiments on 20 cats showed that EHF waves of nonthermal intensity can influence evoked potentials (EP) of the exposed vestibular zone of the cerebral hemispheres. Cerebral cortical exposure to low-frequency EHF waves stimulates negative EP component. Higher frequencies (78.33-118 GHz) reduce the above component amplitude. Changes in the positive EP component were minimal. It is suggested that different effects of millimetric waves diverse frequencies are related to the depth of the radiation penetration into the live tissue. The findings can be used in new techniques of physiotherapy.

  11. 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.

  12. [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

  13. Electroacoustic Comparison of Hearing Aid Output of Phonemes in Running Speech versus Isolation: Implications for Aided Cortical Auditory Evoked Potentials Testing

    PubMed Central

    Easwar, Vijayalakshmi; Purcell, David W.; Scollie, Susan D.

    2012-01-01

    Background. Functioning of nonlinear hearing aids varies with characteristics of input stimuli. In the past decade, aided speech evoked cortical auditory evoked potentials (CAEPs) have been proposed for validation of hearing aid fittings. However, unlike in running speech, phonemes presented as stimuli during CAEP testing are preceded by silent intervals of over one second. Hence, the present study aimed to compare if hearing aids process phonemes similarly in running speech and in CAEP testing contexts. Method. A sample of ten hearing aids was used. Overall phoneme level and phoneme onset level of eight phonemes in both contexts were compared at three input levels representing conversational speech levels. Results. Differences of over 3 dB between the two contexts were noted in one-fourth of the observations measuring overall phoneme levels and in one-third of the observations measuring phoneme onset level. In a majority of these differences, output levels of phonemes were higher in the running speech context. These differences varied across hearing aids. Conclusion. Lower output levels in the isolation context may have implications for calibration and estimation of audibility based on CAEPs. The variability across hearing aids observed could make it challenging to predict differences on an individual basis. PMID:23316236

  14. 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

  15. Evoked Potential Variability

    PubMed Central

    Hu, Lingli; Boutros, Nash N.; Jansen, Ben H.

    2008-01-01

    An unsupervised correlation-based clustering method was developed to assess the trial-to-trial variability of auditory evoked potentials (AEPs). The method first decomposes single trials into three frequency bands, each containing activity primarily associated with one of the three major AEP components, i.e., P50, N100 and P200. Next, single-trial evoked potentials with similar post-stimulus characteristics are clustered and selectively averaged to determine the presence or absence of an AEP component. The method was evaluated on actual AEP and spontaneous EEG data collected from 25 healthy participants using a paradigm in which pairs of identical tones were presented, with the first stimulus (S1) presented 0.5 s before the second stimulus (S2). Homogeneous, well-separated clusters were obtained and substantial AEP variability was found. Also, there was a trend for S2 to produce fewer ‘complete’ (and significantly smaller) responses than S1. Tests conducted on spontaneous EEG produced similar clusters as obtained from EP data, but significantly fewer stimuli produced responses containing all three EP components than seen in AEP data. These findings suggest that the clustering method presented here performs adequately to assess trial-to-trial EP variability. Also, the results suggest that the sensory gating observed in normal controls may be caused by the fact that the second stimulus generates fewer ‘responsive’ trials than the first stimulus, thus resulting in smaller ensemble averages. PMID:19103222

  16. 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

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

    PubMed

    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.

  18. 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

  19. Evoked potentials in multiple sclerosis.

    PubMed

    Kraft, George H

    2013-11-01

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

  20. 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

  1. [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

  2. 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.

  3. 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

  4. Hypothyroidism Affects Olfactory Evoked Potentials

    PubMed Central

    Świdziński, Teodor; Czerniejewska-Wolska, Hanna; Wiskirska-Woźnica, Bożena; Owecki, Maciej; Głowacka, Maria Danuta; Frankowska, Anna; Łącka, Katarzyna; Glapiński, Mariusz; Maciejewska-Szaniec, Zofia; Świdziński, Piotr

    2016-01-01

    Background. Objective electrophysiological methods for investigations of the organ of smell consist in recordings of olfactory cortex responses to specific, time restricted odor stimuli. In hypothyroidism have impaired sense of smell. Material and Methods. Two groups: control of 31 healthy subjects and study group of 21 with hypothyroidism. The inclusion criterion for the study group was the TSH range from 3.54 to 110 μIU/mL. Aim. Assessment of the latency time of evoked responses from the olfactory nerve N1 and the trigeminal nerve N5 using two smells of mint and anise in hypothyroidism. Results. The smell perception in subjective olfactory tests was normal in 85% of the hypothyroid group. Differences were noticed in the objective tests. The detailed intergroup analysis of latency times of recorded cortical responses PN5 and PN1 performed by means between the groups of patients with overt clinical hypothyroidism versus subclinical hypothyroidism demonstrated a significant difference (p < 0.05) whereas no such differences were found between the control group versus subclinical hypothyroidism group (p > 0.05). Conclusion. We can conclude that registration of cortex potentials at irritation of olfactory and trigeminal nerves offers possibilities for using this method as an objective indicator of hypothyroidism severity and prognostic process factor. PMID:27656655

  5. [Intraoperative Visual Evoked Potential Monitoring].

    PubMed

    Hayashi, Hironobu; Kawaguchi, Masahiko

    2015-05-01

    Visual evoked potential (VEP) is recorded from the back of the head, which is elicited by retinal stimulation transmitted through optic nerve, optic chiasm, optic tract lateral geniculate body, optic radiation and finally cortical visual area. VEP monitoring did not prevail since 1990s because marked intra-individual difference and instability of VEP recording limited the clinical usefulness under inhalation anesthetic management and techniques of VEP monitoring at the time. However, recent advances in techniques including a new light-stimulating device consisting of high-luminosity LEDs and induction of electroretinography to ascertain the arrival of the stimulus at the retina provided better conditions for stable VEP recording under general anesthesia. In addition, the introduction of total intravenous anesthesia using propofol is important for the successful VEP recordings because inhaled anesthetics have suppressive effect on VEP waveform. Intraoperative VEP has been considered to monitor the functional integrity of visual function during neurosurgical procedures, in which the optic pathway is at a risk of injury. Intraoperative VEP monitoring may allow us to detect reversible damage to the visual pathway intraoperatively and enable us to prevent permanent impairment.

  6. Hypothyroidism Affects Olfactory Evoked Potentials

    PubMed Central

    Świdziński, Teodor; Czerniejewska-Wolska, Hanna; Wiskirska-Woźnica, Bożena; Owecki, Maciej; Głowacka, Maria Danuta; Frankowska, Anna; Łącka, Katarzyna; Glapiński, Mariusz; Maciejewska-Szaniec, Zofia; Świdziński, Piotr

    2016-01-01

    Background. Objective electrophysiological methods for investigations of the organ of smell consist in recordings of olfactory cortex responses to specific, time restricted odor stimuli. In hypothyroidism have impaired sense of smell. Material and Methods. Two groups: control of 31 healthy subjects and study group of 21 with hypothyroidism. The inclusion criterion for the study group was the TSH range from 3.54 to 110 μIU/mL. Aim. Assessment of the latency time of evoked responses from the olfactory nerve N1 and the trigeminal nerve N5 using two smells of mint and anise in hypothyroidism. Results. The smell perception in subjective olfactory tests was normal in 85% of the hypothyroid group. Differences were noticed in the objective tests. The detailed intergroup analysis of latency times of recorded cortical responses PN5 and PN1 performed by means between the groups of patients with overt clinical hypothyroidism versus subclinical hypothyroidism demonstrated a significant difference (p < 0.05) whereas no such differences were found between the control group versus subclinical hypothyroidism group (p > 0.05). Conclusion. We can conclude that registration of cortex potentials at irritation of olfactory and trigeminal nerves offers possibilities for using this method as an objective indicator of hypothyroidism severity and prognostic process factor.

  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. Vestibular-evoked myogenic potentials.

    PubMed

    Colebatch, J G; Rosengren, S M; Welgampola, M S

    2016-01-01

    The vestibular-evoked myogenic potential (VEMP) is a short-latency potential evoked through activation of vestibular receptors using sound or vibration. It is generated by modulated electromyographic signals either from the sternocleidomastoid muscle for the cervical VEMP (cVEMP) or the inferior oblique muscle for the ocular VEMP (oVEMP). These reflexes appear to originate from the otolith organs and thus complement existing methods of vestibular assessment, which are mainly based upon canal function. This review considers the basis, methodology, and current applications of the cVEMP and oVEMP in the assessment and diagnosis of vestibular disorders, both peripheral and central. PMID:27638068

  9. [Vestibular evoked potentials in people].

    PubMed

    Fraczkowski, K; Pośpiech, L; Orendorz-Fraczkowska, K

    1997-01-01

    In the article had been presented the structure and functioning of a prototype system for stimulation and registration vestibular evoked potentials, and the first recording of evoked vestibular potentials (VsEPs) in human beings. This system consist of a original stimulator accelerated for the stimulation of vestibular organ, modul registratory VsEPs as well as string elements and synchronizing stimulation with recording. IMB PC 486 is quickly process of investigation with help of standard interface and a original computer programme. Vestibular organ had been evoked by 200 to 500 cyclicly repealed angular decelerations of 4000 degrees/s2. During investigation white noise was used for masking to avoid the evoking of auditory potentials. Seven of the examined healthy persons (including one deaf person whose vestibular organ was not damaged) had registered a response consisting of several waves with vertex positive peaks. The first two waves P1 and P2 with the mean value 2.02 ms and 5.6 ms are most often during in the 10 ms. The registered deaf persons response does not differ from the record of healthy persons. PMID:9518319

  10. Local and thalamic origins of correlated ongoing and sensory-evoked cortical activities

    PubMed Central

    Cohen-Kashi Malina, Katayun; Mohar, Boaz; Rappaport, Akiva N.; Lampl, Ilan

    2016-01-01

    Thalamic inputs of cells in sensory cortices are outnumbered by local connections. Thus, it was suggested that robust sensory response in layer 4 emerges due to synchronized thalamic activity. To investigate the role of both inputs in the generation of correlated cortical activities, we isolated the thalamic excitatory inputs of cortical cells by optogenetically silencing cortical firing. In anaesthetized mice, we measured the correlation between isolated thalamic synaptic inputs of simultaneously patched nearby layer 4 cells of the barrel cortex. Here we report that in contrast to correlated activity of excitatory synaptic inputs in the intact cortex, isolated thalamic inputs exhibit lower variability and asynchronous spontaneous and sensory-evoked inputs. These results are further supported in awake mice when we recorded the excitatory inputs of individual cortical cells simultaneously with the local field potential in a nearby site. Our results therefore indicate that cortical synchronization emerges by intracortical coupling. PMID:27615520

  11. [Personality dimensions and cerebral evoked potential].

    PubMed

    Camposano, S; Alvarez, C; Lolas, F

    1994-12-01

    Eysenck's personality theory postulates 3 orthogonal dimensions of personality: extraversion (E), neuroticism (N) and psychoticism (P), predicting conductual and physiological predispositions to suffer mental illness. Biological bases of Eysenck's personality traits have been documented electrophysiologically. Psychoticism, the latest described dimension, is controverted, since there is some evidence of common factors with the other two. In order to assess the relation between Eysenck's dimensions and sensorial reactivity and information encoding processes we studied 20 healthy young subjects (mean age 28.5 years) with flash visual cortical evoked potentials (VEP, 3 intensities, peak to peak amplitude of III, IV-V-VI, VII components), and auditory cognitive evoked potentials (odd ball paradigm, P300 latency). There was a positive correlation between N and P dimensions (Spearman, r = 0.52), between N and VEP amplitude at high intensity (r = 0.58) and a negative correlation between E and P300 latency (r = 0.58). In short we found that P is not an independent dimension, but is related to sensorial reactivity. E dimension was related to encoding processes supporting Eysenck's observations about memory and learning differences.

  12. 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

  13. 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

  14. [Long-latency auditory evoked potentials in cochlear implants].

    PubMed

    Mata, J J; Jiménez, J M; Pérez, J; Postigo, A; Roldán, B

    1999-01-01

    Cortical evoked potentials were evaluated in patients with cochlear implants. In a group of 8 adults of different ages, the lingual state before implantation and during rehabilitation were evaluated. Using cortical evoked potentials, the results of the P300 wave in response to two tones, one frequent (1,000 Hz) and the other infrequent (2,000 Hz), presented at 70 and 80 dB HL were studied. Results were analyzed and compared in relation to locutive state, rehabilitation stage, and intensity of stimulus. Absolute latencies did not differ significantly. However, latency values in relation to reaction time were significantly longer in prelingual than in postlingual patients (p < 0.05, Student test). The results confirmed the normality of central cognitive processes in patients with cochlear implants in objective assessment of P300 latency. The results suggest differences between prelingual and postlingual patients in relation to central signal processing.

  15. Effects of pulse phase duration and location of stimulation within the inferior colliculus on auditory cortical evoked potentials in a guinea pig model.

    PubMed

    Neuheiser, Anke; Lenarz, Minoo; Reuter, Guenter; Calixto, Roger; Nolte, Ingo; Lenarz, Thomas; Lim, Hubert H

    2010-12-01

    The auditory midbrain implant (AMI), which consists of a single shank array designed for stimulation within the central nucleus of the inferior colliculus (ICC), has been developed for deaf patients who cannot benefit from a cochlear implant. Currently, performance levels in clinical trials for the AMI are far from those achieved by the cochlear implant and vary dramatically across patients, in part due to stimulation location effects. As an initial step towards improving the AMI, we investigated how stimulation of different regions along the isofrequency domain of the ICC as well as varying pulse phase durations and levels affected auditory cortical activity in anesthetized guinea pigs. This study was motivated by the need to determine in which region to implant the single shank array within a three-dimensional ICC structure and what stimulus parameters to use in patients. Our findings indicate that complex and unfavorable cortical activation properties are elicited by stimulation of caudal-dorsal ICC regions with the AMI array. Our results also confirm the existence of different functional regions along the isofrequency domain of the ICC (i.e., a caudal-dorsal and a rostral-ventral region), which has been traditionally unclassified. Based on our study as well as previous animal and human AMI findings, we may need to deliver more complex stimuli than currently used in the AMI patients to effectively activate the caudal ICC or ensure that the single shank AMI is only implanted into a rostral-ventral ICC region in future patients.

  16. [Brainstem auditory evoked potentials and somatosensory evoked potentials in Chiari malformation].

    PubMed

    Moncho, Dulce; Poca, María A; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

    2013-06-16

    Introduccion. La malformacion de Chiari (MC) incluye una serie de anomalias congenitas que tienen como comun denominador la ectopia de las amigdalas del cerebelo por debajo del foramen magno, lo que puede condicionar fenomenos compresivos del troncoencefalo, la medula espinal alta y los nervios craneales, alterando las respuestas de los potenciales evocados auditivos del tronco cerebral (PEATC) y de los potenciales evocados somatosensoriales (PESS). Sin embargo, las indicaciones de ambas exploraciones en las MC han sido motivo de estudio en un numero limitado de publicaciones, centradas en series cortas y heterogeneas de pacientes. Objetivo. Revisar los hallazgos de los PEATC y los PESS en los estudios publicados en pacientes con MC tipo 1 (MC-1) o tipo 2 (MC-2), y su indicacion en el diagnostico, tratamiento y seguimiento, especialmente en la MC-1. Desarrollo. Es un estudio de revision realizado mediante analisis de los estudios publicados en Medline desde 1966, localizados mediante PubMed, utilizando combinaciones de las palabras clave 'Chiari malformation', 'Arnold-Chiari malformation', 'Chiari type 1 malformation', 'Arnold-Chiari type 1 malformation', 'evoked potentials', 'brainstem auditory evoked potentials' y 'somatosensory evoked potentials', asi como informacion de pacientes con MC-1 valorados en los servicios de neurocirugia y neurofisiologia clinica del Hospital Universitari Vall d'Hebron. Conclusiones. Los hallazgos mas comunes de los PESS son la reduccion en la amplitud cortical para el nervio tibial posterior, la reduccion o ausencia del potencial cervical del nervio mediano y el aumento del intervalo N13-N20. En el caso de los PEATC, los hallazgos mas frecuentes descritos son el aumento del intervalo I-V y la alteracion periferica o coclear.

  17. 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.

  18. Auditory evoked potentials and transcendental meditation.

    PubMed

    Barwood, T J; Empson, J A; Lister, S G; Tilley, A J

    1978-11-01

    Auditory evoked potentials to tone stimuli were recorded from 8 practised meditators before, during, and after meditation, and also during light sleep. No consistent changes were noted between baseline and meditating AEPs, or between meditating and sleep AEPs.

  19. Non-invasive modulation of somatosensory evoked potentials by the application of static magnetic fields over the primary and supplementary motor cortices

    PubMed Central

    Kirimoto, Hikari; Asao, Akihiko; Tamaki, Hiroyuki; Onishi, Hideaki

    2016-01-01

    This study was performed to investigate the possibility of non-invasive modulation of SEPs by the application of transcranial static magnetic field stimulation (tSMS) over the primary motor cortex (M1) and supplementary motor cortex (SMA), and to measure the strength of the NdFeB magnetic field by using a gaussmeter. An NdFeB magnet or a non-magnetic stainless steel cylinder (for sham stimulation) was settled on the scalp over M1 and SMA of 14 subjects for periods of 15 min. SEPs following right median nerve stimulation were recorded before and immediately after, 5 min after, and 10 min after tSMS from sites C3′ and F3. Amplitudes of the N33 component of SEPs at C3′ significantly decreased immediately after tSMS over M1 by up to 20%. However, tSMS over the SMA did not affect the amplitude of any of the SEP components. At a distance of 2–3 cm (rough depth of the cortex), magnetic field strength was in the range of 110–190 mT. Our results that tSMS over M1 can reduce the amplitude of SEPs are consistent with those of low-frequency repeated TMS and cathodal tDCS studies. Therefore, tSMS could be a useful tool for modulating cortical somatosensory processing. PMID:27698365

  20. 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

  1. Brainstem auditory evoked potentials and middle latency auditory evoked potentials in young children.

    PubMed

    Luo, Jin Jun; Khurana, Divya S; Kothare, Sanjeev V

    2013-03-01

    Measurements of brainstem auditory evoked potentials (BAEP) and middle latency auditory evoked potentials (MLAEP) are readily available neurophysiologic assessments. The generators for BAEP are believed to involve the structures of cochlear nerve, cochlear nucleus, superior olive complex, dorsal and rostral pons, and lateral lemniscus. The generators for MLAEP are assumed to be located in the subcortical area and auditory cortex. BAEP are commonly used in evaluating children with autistic and hearing disorders. However, measurement of MLAEP is rarely performed in young children. To explore the feasibility of this procedure in young children, we retrospectively reviewed our neurophysiology databank and charts for a 3-year period to identify subjects who had both BAEP and MLAEP performed. Subjects with known or identifiable central nervous system abnormalities from the history, neurologic examination and neuroimaging studies were excluded. This cohort of 93 children up to 3 years of age was divided into 10 groups based on the age at testing (upper limits of: 1 week; 1, 2, 4, 6, 8, 10 and 12 months; 2 years; and 3 years of age). Evolution of peak latency, interpeak latency and amplitude of waveforms in BAEP and MLAEP were demonstrated. We concluded that measurement of BAEP and MLAEP is feasible in children, as early as the first few months of life. The combination of both MLAEP and BAEP may increase the diagnostic sensitivity of neurophysiologic assessment of the integrity or functional status of both the peripheral (acoustic nerve) and the central (brainstem, subcortical and cortical) auditory conduction systems in young children with developmental speech and language disorders.

  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. [Evoked potentials in patients with secondary headaches].

    PubMed

    Iakupov, E Z; Kuznetsova, E A

    2010-01-01

    Characteristics of brain evoked activity were studied in patients with most frequent variants of secondary headaches: chronic posttraumatic headaches, cervicogenic headaches and vascular headaches in patients with arterial hypertension and chronic brain ischemia. The multimodal registration of evoked potentials (EP) (short-latency brainstem auditory, visual EPs to flash stimulation and cognitive EPs - P300) revealed signs of brainstem dysfunction, decrease of visual analyzer and diminished cognitive functions in most patients with secondary headaches. Based on results obtained, we can recommend a complex therapy of chronic secondary headaches with neuroprotectors and nootropics.

  4. Human evoked cortical activity to signal-to-noise ratio and absolute signal level.

    PubMed

    Billings, Curtis J; Tremblay, Kelly L; Stecker, G Christopher; Tolin, Wendy M

    2009-08-01

    The purpose of this study was to determine the effect of signal level and signal-to-noise ratio (SNR) on the latency and amplitude of evoked cortical activity to further our understanding of how the human central auditory system encodes signals in noise. Cortical auditory evoked potentials (CAEPs) were recorded from 15 young normal-hearing adults in response to a 1000 Hz tone presented at two tone levels in quiet and while continuous background noise levels were varied in five equivalent SNR steps. These 12 conditions were used to determine the effects of signal level and SNR level on CAEP components P1, N1, P2, and N2. Based on prior signal-in-noise experiments conducted in animals, we hypothesized that SNR, would be a key contributor to human CAEP characteristics. As hypothesized, amplitude increased and latency decreased with increasing SNR; in addition, there was no main effect of tone level across the two signal levels tested (60 and 75 dB SPL). Morphology of the P1-N1-P2 complex was driven primarily by SNR, highlighting the importance of noise when recording CAEPs. Results are discussed in terms of the current interest in recording CAEPs in hearing aid users.

  5. 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.

  6. Intraoperative monitoring of evoked potentials.

    PubMed

    Raudzens, P A

    1982-01-01

    Sensory EPs were recorded intraoperatively in 173 neurosurgical procedures (71 VEPs, 66 BAEPs, and 31 SSEPs) to evaluate the utility of this technique. EPs could be safely recorded in all cases, but the yield of useful results varied with each sensory modality. BAEPs were recorded reliably in 100% of the cases and intraoperative latency changes accurately predicted postoperative hearing deficits in 10%. Potential hearing deficits were detected in another 15%. BAEP changes were associated with brainstem dysfunction in only one case. VEP changes were difficult to interpret intraoperatively because of contamination by a high degree of variability and both false negative and false positive results. Changes in VEP amplitudes related to surgical manipulation of the optic chiasm were only suggested. SSEP changes were recorded reliably in only 75% of the cases and no correlations between SSEP changes and postoperative sensory function were established. Again, intraoperative amplitude attenuation of the SSEP waveform with surgical manipulation only suggested a potential sensory deficit. Intraoperative EP monitoring is a valuable technique that provides a functional analysis of the sensory nervous system during surgical procedures. Specific sensory stimuli and improved data analysis will increase the utility of this CNS monitor.

  7. Localizing evoked cortical activity associated with balance reactions: does the anterior cingulate play a role?

    PubMed

    Marlin, Amanda; Mochizuki, George; Staines, William R; McIlroy, William E

    2014-06-15

    The ability to correct balance disturbances is essential for the maintenance of upright stability. Although information about how the central nervous system controls balance reactions in humans remains limited, recent literature highlights a potentially important role for the cerebral cortex. The objective of this study was to determine the neural source of the well-reported balance-evoked N1 response. It was hypothesized that the N1 is associated with an "error-detection" event in response to the induced perturbation and therefore may be associated with activity within the anterior cingulate cortex (ACC). The localized source of the N1 evoked by perturbations to standing balance was compared, within each participant, to the location of an error-related negativity (ERN) known to occur within the ACC while performing a flanker task. In contrast to the main hypotheses, the results revealed that the location of the N1 was not within the ACC. The mean Talairach coordinates for the ERN were (6.47, -4.41, 41.17) mm, corresponding to the cingulate gyrus [Brodmann area (BA) 24], as expected. However, coordinates for the N1 dipole were (5.74, -11.81, 53.73) mm, corresponding to the medial frontal gyrus (BA 6), specifically the supplementary motor area. This may suggest the N1 is linked to the planning and execution of elements of the evoked balance reactions rather than being associated with error or event detection. Alternatively, it is possible that the N1 is associated with variation in the cortical representation due to task-specific differences in the activation of a distributed network of error-related processing. Subsequent work should focus on disentangling these two possible explanations as they relate to the cortical processing linked to reactive balance control.

  8. The inhibitory neurotransmitter GABA evokes long‐lasting Ca2+ oscillations in cortical astrocytes

    PubMed Central

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

    2015-01-01

    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 Ca2+ 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 Ca2+ 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 Ca2+ elevations. At all astrocytic processes tested, local GABA or Baclofen brief applications induced long‐lasting Ca2+ oscillations, suggesting that all astrocytes have the potential to respond to GABA. Finally, in patch‐clamp recordings it was found that Ca2+ oscillations induced by Baclofen evoked astrocytic glutamate release and slow inward currents (SICs) in pyramidal cells from wild type but not IP3R2−/− mice, in which astrocytic GABAB receptor‐mediated Ca2+ 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. GLIA 2016;64:363–373 PMID:26496414

  9. 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

  10. Perceptual learning of acoustic noise generates memory-evoked potentials.

    PubMed

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-01

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics.

  11. Beaked whale auditory evoked potential hearing measurements.

    PubMed

    Cook, Mandy L H; Varela, René A; Goldstein, Juli D; McCulloch, Stephen D; Bossart, Gregory D; Finneran, James J; Houser, Dorian; Mann, David A

    2006-05-01

    Several mass strandings of beaked whales have recently been correlated with military exercises involving mid-frequency sonar highlighting unknowns regarding hearing sensitivity in these species. We report the hearing abilities of a stranded juvenile beaked whale (Mesoplodon europaeus) measured with auditory evoked potentials. The beaked whale's modulation rate transfer function (MRTF) measured with a 40-kHz carrier showed responses up to an 1,800 Hz amplitude modulation (AM) rate. The MRTF was strongest at the 1,000 and 1,200 Hz AM rates. The envelope following response (EFR) input-output functions were non-linear. The beaked whale was most sensitive to high frequency signals between 40 and 80 kHz, but produced smaller evoked potentials to 5 kHz, the lowest frequency tested. The beaked whale hearing range and sensitivity are similar to other odontocetes that have been measured.

  12. Evoked potentials in pediatrics: economic audit.

    PubMed

    Chiozza, M L; Suppiej, A; Zacchello, F

    1997-03-01

    In the present era of resource management, there is increasing emphasis on the need to make the best possible use of available resources. We therefore measured the productive factors directly involved in performance of 59 evoked potential examinations (brainstem auditory evoked potentials, BAEPs; flash visual evoked potentials, F-VEPs; and electroretinograms, ERGs) in different pediatric age groups. In order to ascertain the gap between the costs of instrumental examinations performed in our service on children and the fees reimbursed by the Italian national health service (NHS) a breakdown was made of the costs of tests and their scheduling in relation to the different age variables involved. It was found that the fees reimbursed do not cover the real costs, because they underestimate the actual consumption of resources. The findings recorded indicate that for pediatric tests the economic audit should be graded according to the ages of the children examined and should include an analysis of different test phases. The economic audit should also be considered a preliminary step in clinical audit. It is concluded that it is financially punitive to reimburse a pediatric service with a fee based on the examination of adults, because in pediatrics the variable "age" influences the duration and complexity of tests and also their interpretation.

  13. 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…

  14. Voluntary alteration of visual evoked potentials.

    PubMed

    Bumgartner, J; Epstein, C M

    1982-11-01

    Fifteen normal adults had pattern-shift visual evoked potentials (PSVEPs) using monocular checkerboard pattern reversal. Subjects were instructed to concentrate on the pattern in the first set of trials and then to avoid perceiving it in the second set. Direct, continuous visual observation ensured that the eye remained open and fixed on the pattern. Nonetheless, a third of the subjects could spontaneously alter or obliterate the PSVEP using several maneuvers, including meditation, daydreaming, and convergence. Several could produce shifts in apparent PSVEP latency. With explicit instruction, most subjects could learn to alter their PSVEP by maneuvers that are inapparent even to an observent technician.

  15. Visual evoked potentials in occipital lobe lesions.

    PubMed

    Streletz, L J; Bae, S H; Roeshman, R M; Schatz, N J; Savino, P J

    1981-02-01

    Recording of visual evoked potentials (VEPs) to pattern reversal is considered to be a reliable diagnostic procedure for examining patients with anterior visual pathway lesions (optic nerves and chiasm). Less consistent results have been reported in studies of more posterior lesions. The VEPs were recorded in 20 patients with occipital lobe lesions. A maximal VEP response (P94) was recorded at the scalp electrodes situated over the involved occipital lobes and contralateral to the hemianoptic visual field defect, indicating a positive correlation of unilateral occipital lobe lesions, homonymous visual field loss, and the VEP abnormality.

  16. Pattern reversal visual evoked potentials in phenylketonuria.

    PubMed

    Giovannini, M; Valsasina, R; Villani, R; Ducati, A; Riva, E; Landi, A; Longhi, R

    1988-01-01

    The pathogenesis of brain dysfunction in phenylketonuria (PKU) is still under investigation. Hyperphenylalaninaemia results in increased turnover of myelin. In order to demonstrate the derangement of myelinization in PKU we studied the visual evoked potentials (VEP) in 14 PKU patients and in 20 normal subjects. VEP findings were correlated with the metabolic control of the disease and with the electroencephalographic findings. VEP were more sensitive than the EEG in detecting a neurological dysfunction. VEP are influenced by dietary control and are normal only in children with good metabolic control.

  17. [Intraoperative monitoring: visual evoked potentials in surgery of the sellar region].

    PubMed

    Lorenz, M; Renella, R R

    1989-01-01

    During 18 sellar and perisellar operations the optic tract was monitored by visual evoked potentials (VEP). Deteriorations of the cortical responses were recorded in 73%. In this patients there was no close correlation between the intraoperative findings and the postoperative visual function. Only in those patients who showed no remarkable intraoperative changes VEP seemed to be of reliable prognostic value.

  18. Long Latency Auditory Evoked Potential in Term and Premature Infants

    PubMed Central

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

    2013-01-01

    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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. Somatosensory evoked potentials during natural and learning rearrangements of posture accompanied by limb elevation in dogs.

    PubMed

    Gavrilenko, T; Frolov, A G; Ioffe, M E; Ganchev, G N; Aleksandrov, A V; Pavlova, O G

    2002-01-01

    Changes in the functional state of the sensorimotor cortex associated with reorganization of the natural pattern of postural rearrangement before limb elevation (the "diagonal" patten and of an artificial rearrangement (the "unilateral" pattern) were studied in dogs. The state of cortical structures on postural rearrangement was assessed in terms of the pattern of somatosensory evoked potentials produced in response to stimulation of the forelimb during postural preparation of the animal for elevating the hindlimb (acquired avoidance response to a sound signal). Evoked potentials during the natural postural preparation (the "diagonal" pattern) were compared with those during the altered pattern of postural preparation (the "unilateral" pattern), this preparation taking place prior to elevation of the limb. Controls consisted of evoked potentials in the resting state. Decreases were seen in the latencies and amplitudes of most components of evoked potentials during postural rearrangement. In general, changes in evoked potentials were less marked in the "unilateral" pattern than in the "diagonal" pattern, though the differences were significant only for the amplitude of the first negative component. Changes in evoked potentials were similar regardless of whether the supporting forces of the limb to which the test stimulus was applied increased or decreased during postural rearrangement. It is suggested that differences in evoked potentials may reflect changes in the interaction between neuronal populations within the sensorimotor cortex during reorganization of the pattern of postural rearrangement associated with learning.

  4. 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

  5. Multimodality evoked potentials in HIV infected subjects: a longitudinal study.

    PubMed

    Cazzullo, C L; Gala, C; Ducati, A; Landi, A; Donati, R; Russo, R; Rossini, M; Nicolosi, A

    1990-10-01

    18 subjects with symptomless HIV infection were investigated with multimodal evoked potentials for possible CNS involvement and again after an 8-12 month interval. 13 subjects showed neuropsychological changes, which were confirmed at the second examination. The 5 subjects found normal remained so at the second examination. On WAIS assessment the only patient to earn pathological scores was the one with the greatest evoked potentials changes. Thus the evoked potentials procedure proved capable of identifying early CNS involvement by HIV infection.

  6. Somatosensory evoked potentials and neuraxial blood flow in central nervous system decompression sickness.

    PubMed

    Leitch, D R; Hallenbeck, J M

    1984-10-01

    Seven adult, conditioned dogs were anesthetized with pentobarbital sodium and prepared for measurement of upper lumbar, mid-thoracic and lower cervical spinal evoked potentials (SEPs), cortical evoked potential (CEP), and aortic, right ventricular, and cerebrospinal fluid pressures. Following preparation, one animal was monitored by means of repeated evoked potentials for 2 h, at which time a [14C]iodoantipyrine autoradiographic blood flow study was performed. The 6 other animals were exposed to simulated dives in a compression chamber while anesthesia was maintained through a chamber penetration. These animals developed decompression sickness (DCS) of varying severity upon returning to the surface, and the corresponding decrements in neuronal function of the cord and the brain were measured by means of serial SEP and CEP recording. Following this evoked potential recording, [14C]iodoantipyrine autoradiographic blood flow studies were performed. The results indicated that clear reductions in SEP and CEP amplitude were associated with very low blood flows, which were in the 'neuron-disabling' range. Spinal and cortical somatosensory evoked potentials provide a valuable index with which to monitor and manage a model of spinal cord DCS. PMID:6498488

  7. 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.

  8. Cortico-centric effects of general anesthetics on cerebrocortical evoked potentials.

    PubMed

    Voss, Logan J; Sleigh, James W

    2015-12-01

    Despite their ubiquitous use for rendering patients unconscious for surgery, our understanding of how general anesthetics cause hypnosis remains rudimentary at best. Recent years have seen increased interest in "top-down" cortico-centric theories of anesthetic action. The aim of this study was to explore this by investigating direct cortical effects of anesthetics on cerebrocortical evoked potentials in isolated mouse brain slices. Evoked potentials were elicited in cortical layer IV by electrical stimulation of the underlying white matter. The effects of three anesthetics (ketamine, etomidate, and isoflurane) on the amplitude, latency, and slope of short-latency evoked potentials were quantified. The N2/P3/N4 potentials–which represent the early cortical response–were enhanced by etomidate (increased P3-N4 slope, P <0.01), maintained by ketamine, and reduced by isoflurane (lower N2/P3 amplitude, P <0.01). These effects closely resemble those seen in vivo for the same drugs and point to a cortical mechanism independent of effects on subcortical structures such as the thalamus.

  9. Caloric vestibular stimulation modulates nociceptive evoked potentials.

    PubMed

    Ferrè, Elisa Raffaella; Haggard, Patrick; Bottini, Gabriella; Iannetti, Gian Domenico

    2015-12-01

    Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. To investigate how vestibular inputs influence nociception, we combined caloric vestibular stimulation (CVS) with psychophysical and electrocortical responses elicited by nociceptive-specific laser stimulation in humans (laser-evoked potentials, LEPs). Cold water CVS applied to the left ear resulted in significantly lower subjective pain intensity for experimental laser pain to the left hand immediately after CVS, relative both to before CVS and to 1 h after CVS. This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated either by subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex.

  10. [Intraoperative monitoring of visual evoked potentials].

    PubMed

    Sasaki, Tatsuya; Ichikawa, Tsuyoshi; Sakuma, Jun; Suzuki, Kyouichi; Matsumoto, Masato; Itakura, Takeshi; Kodama, Namio; Murakawa, Masahiro

    2006-03-01

    Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

  11. 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.

  12. Axonal and somatic filtering of antidromically evoked cortical excitation by simulated deep brain stimulation in rat brain

    PubMed Central

    Chomiak, T; Hu, B

    2007-01-01

    Antidromic cortical excitation has been implicated as a contributing mechanism for high-frequency deep brain stimulation (DBS). Here, we examined the reliability of antidromic responses of type 2 corticofugal fibres in rat over a stimulation frequency range compatible to the DBS used in humans. We activated antidromically individual layer V neurones by stimulating their two subcortical axonal branches. We found that antidromic cortical excitation is not as reliable as generally assumed. Whereas the fast conducting branches of a type 2 axon in the highly myelinated brainstem region follow high-frequency stimulation, the slower conducting fibres in the poorly myelinated thalamic region function as low-pass filters. These fibres fail to transmit consecutive antidromic spikes at the beginning of high-frequency stimulation, but are able to maintain a steady low-frequency (6–12 Hz) spike output during the stimulation. In addition, antidromic responses evoked from both branches are rarely present in cortical neurones with a more hyperpolarized membrane potential. Our data indicate that axon-mediated antidromic excitation in the cortex is strongly influenced by the myelo-architecture of the stimulation site and the excitability of individual cortical neurones. PMID:17170044

  13. 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

  14. [Vestibular evoked potentials in "Gallus Domesticus"].

    PubMed

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

    1989-01-01

    Electrophysiological activity in response to linear acceleration stimuli was recorded from Gallus Domesticus by means of subcutaneous electrodes. This investigation had two purposes: 1) to obtain normative data for our laboratory, and 2) to rule out auditory and somatosensory contributions to the Vestibular Evoked Potentials (VsEP). The stimulus consisted of a sigmoid-shaped voltage function generated by a digital-to-analog converter. This signal was amplified, attenuated, and directed to a shaker (selenoid-based, linear mechanical vibrator). The animal's head was firmly attached to a small platform which in turn was coupled to the transducer. The recorded electrophysiological activity was filtered, amplified, and averaged over 256 stimulus presentations. The VsEP are composed of a positive wave, a prominent negativity, and three to five additional positive waves which occur within the first 10 milliseconds following the stimulus. The first three elements are the most robust components of the response. Latency/acceleration and amplitude/acceleration functions were constructed for each of these three waves. Clear and replicable responses were obtained at an acceleration of 2.00 g. At this level the amplitude of the components ranged between 3 and 5 microvolts. On the average, threshold responses were recorded at 0.0935 g. VsEP were not affected by high intensity white noise. However, bilateral intralabyrinthine injection of tetrodotoxin (TTX), a voltage-gated sodium channel blocker, abolished the responses. These results suggest that the activity recorded in response to linear acceleration stimuli is of vestibular origin. PMID:2635851

  15. Electroretinography and Visual Evoked Potentials in Childhood Brain Tumor Survivors.

    PubMed

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

    2016-07-01

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

  16. Enhancement of the amplitude of somatosensory evoked potentials following magnetic pulse stimulation of the human brain.

    PubMed

    Seyal, M; Browne, J K; Masuoka, L K; Gabor, A J

    1993-01-01

    In this study we have demonstrated an enhancement of cortically generated wave forms of the somatosensory evoked potential (SEP) following magnetic pulse stimulation of the human brain. Subcortically generated activity was unaltered. The enhancement of SEP amplitude was greatest when the median nerve was stimulated 30-70 msec following magnetic pulse stimulation over the contralateral parietal scalp. We posit that the enhancement of the SEP is the result of synchronization of pyramidal cells in the sensorimotor cortex resulting from the magnetic pulse.

  17. 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

  18. Cochlear Implant-Evoked Cortical Activation in Children with Cochlear Nerve Deficiency

    PubMed Central

    He, Shuman; Grose, John; Hang, Anna X.; Buchman, Craig A.

    2012-01-01

    Objective To report the results of cochlear implant-elicited cortical auditory evoked potentials (eCAEP) in children with cochlear nerve deficiency (CND). Study Design Case control series. Setting Tertiary academic referral center. Patients Seven children with CND that have a cochlear implant in their affected ear. Four children without CND served as controls. Intervention(s) eCAEPs were elicited by activation of individual cochlear implant electrodes. Main Outcome Measure(s) Onset responses (P1-N1-P2 complex). Results Three of 7 CND children demonstrated eCAEP responses across a broad range of electrodes despite having limited or no open set speech perception abilities using their implants. Two of these children had eCAEPs that were characterized by substantial variability in latency, amplitude, and number of electrodes with identifiable responses. The remaining 4 ears with CND and poor speech perception had multiphasic responses that are inconsistent with eCAEPs. Non-CND ears with excellent speech perception abilities demonstrated robust responses on all electrodes stimulated. Conclusions Abent eCAEP responses were indicative of poor open-set speech perception skills in all cases. However, eCAEP onset responses were measurable in some children with imaging evidence of CND, indicating probable cochlear nerve hypoplasia rather than aplasia. That some children with CND and poor speech perception had robust eCAEPs in some instances makes this particular measure of limited utility for predicting good speech perception outcomes following cochlear implantation in these children. The origin of multiphasic responses remains to be determined but may be of somatosensory origin in some instances. PMID:22872179

  19. 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

  20. 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

  1. 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

  2. Cortical speech-evoked response patterns in multiple auditory fields are correlated with behavioral discrimination ability.

    PubMed

    Centanni, T M; Engineer, C T; Kilgard, M P

    2013-07-01

    Different speech sounds evoke unique patterns of activity in primary auditory cortex (A1). Behavioral discrimination by rats is well correlated with the distinctness of the A1 patterns evoked by individual consonants, but only when precise spike timing is preserved. In this study we recorded the speech-evoked responses in the primary, anterior, ventral, and posterior auditory fields of the rat and evaluated whether activity in these fields is better correlated with speech discrimination ability when spike timing information is included or eliminated. Spike timing information improved consonant discrimination in all four of the auditory fields examined. Behavioral discrimination was significantly correlated with neural discrimination in all four auditory fields. The diversity of speech responses across recordings sites was greater in posterior and ventral auditory fields compared with A1 and anterior auditor fields. These results suggest that, while the various auditory fields of the rat process speech sounds differently, neural activity in each field could be used to distinguish between consonant sounds with accuracy that closely parallels behavioral discrimination. Earlier observations in the visual and somatosensory systems that cortical neurons do not rely on spike timing should be reevaluated with more complex natural stimuli to determine whether spike timing contributes to sensory encoding.

  3. 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.

  4. 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…

  5. 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

  6. 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.

  7. Chronic network stimulation enhances evoked action potentials

    NASA Astrophysics Data System (ADS)

    Ide, A. N.; Andruska, A.; Boehler, M.; Wheeler, B. C.; Brewer, G. J.

    2010-02-01

    Neurons cultured on multielectrode arrays almost always lack external stimulation except during the acute experimental phase. We have investigated the effects of chronic stimulation during the course of development in cultured hippocampal neural networks by applying paired pulses at half of the electrodes for 0, 1 or 3 r/day for 8 days. Spike latencies increased from 4 to 16 ms as the distance from the stimulus increased from 200 to 1700 µm, suggesting an average of four synapses over this distance. Compared to no chronic stimulation, our results indicate that chronic stimulation increased evoked spike counts per stimulus by 50% at recording sites near the stimulating electrode and increased the instantaneous firing rate. On trials where both pulses elicited responses, spike count was 40-80% higher than when only one of the pulses elicited a response. In attempts to identify spike amplitude plasticity, we found mainly amplitude variation with different latencies suggesting recordings from neurons with different identities. These data suggest plastic network changes induced by chronic stimulation that enhance the reliability of information transmission and the efficiency of multisynaptic network communication.

  8. 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

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

    PubMed

    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.

  10. 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

  11. 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.

  12. Intermittent cortical stimulation evokes sensitization to cocaine and enduring changes in matrix and striosome neuron responsiveness.

    PubMed

    Canales, Juan J

    2005-07-01

    Both the behavioral sensitization syndrome and the changes in the responsiveness of striatal neurons evoked by chronic cocaine exposure may be linked to enhanced neocortical activity, yet a direct demonstration of the effects of cortical stimulation on these parameters is lacking. We have found that repeated stimulation of the rat prelimbic cortex with picrotoxin (0.25 microg/0.25 microl, five injections on alternate days followed by 7-day withdrawal) contributed to increase c-Fos protein expression in the striosomes of the dorsolateral striatum, while producing the opposite effect in the matrix compartment, after a single exposure to cocaine (25 mg/kg). Moreover, rats exposed to cortical stimulation showed decreased locomotor activation but enhanced stereotypy following acute cocaine treatment. Thus, pulsatile stimulation of the prelimbic cortex facilitated modifications in striatal activity typically produced by chronic cocaine treatment and sensitized drug-naive animals to acute cocaine challenge. These results suggest that enhanced activation of the prelimbic cortex may contribute to the long-term adaptations induced by cocaine on neural activity and behavior.

  13. 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

  14. 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

  15. [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

  16. [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

  17. [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

  18. Changes in brainstem and cortical auditory potentials during Qi-Gong meditation.

    PubMed

    Liu, G L; Cui, R Q; Li, G Z; Huang, C M

    1990-01-01

    "Qi Gong" (QG) is a meditation exercise known for thousands of years in China and has always been widely practiced. It has been claimed to have a variety of healing and other health benefits. To provide an understanding of the effect of QG on brain structures along the whole neural axis from the periphery to the cerebral cortex, we have monitored short-latency auditory brainstem evoked response, middle-latency response, and long-latency cortical auditory evoked potentials, before, during, and after QG. Our results showed that QG caused an enhancement of brainstem auditory evoked response with a concomitant depression of cortical responses. These observations may be related to the healing and other health benefits of QG.

  19. 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.

  20. Auditory evoked potentials and impairments to psychomotor activity evoked by falling asleep.

    PubMed

    Dorokhov, V B; Verbitskaya, Yu S; Lavrova, T P

    2010-05-01

    Sounds provide the most suitable stimuli for studies of information processes occurring in the brain during falling asleep and at different stages of sleep. The widely used analysis of evoked potentials averaged for groups of subjects has a number of disadvantages associated with their individual variability. Thus, in the present study, measures of the individual components of auditory evoked potentials were determined and selectively summed for individual subjects, with subsequent analysis by group. The aim of the present work was to identify measures of auditory evoked potentials providing quantitative assessment of the dynamics of the brain's functional state during the appearance of errors in activity associated with decreases in the level of waking and falling asleep. A monotonous psychomotor test was performed in the lying position with the eyes closed; this consisted of two alternating parts: the first was counting auditory stimuli from 1 to 10 with simultaneous pressing of a button, and the second was counting stimuli from 1 to 5 silently without pressing the button, and so on. Computer-generated sound stimuli (duration 50 msec, envelope filling frequency 1000 Hz, intensity 60 dB) were presented binaurally with interstimulus intervals of 2.4-2.7 sec. A total of 41 subjects took part (both genders, mean age 25 years), of which only 23 fell asleep; data for 14 subjects with sufficient episodes of falling asleep were analyzed. Comparison of measures of auditory evoked potentials (the latencies and amplitudes of the N1, P2, N2, and P3 components) during correct and erroneous psychomotor test trials showed that decreases in the level of consciousness elicited significant increases in the amplitudes of the components of the vertex N1-P2-N2 complex in series without button pressing. The greatest changes in auditory evoked potentials in both series were seen in the N2 component, with latency 330-360 msec, which has a common origin with the EEG theta rhythm and is

  1. 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.

  2. 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.

  3. 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…

  4. 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

  5. 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

  6. 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

  7. 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

  8. [Visual evoked potentials (VEP) in anesthesia and intensive care].

    PubMed

    Russ, W; Krumholz, W; Hempelmann, G

    1984-03-01

    Methodological considerations and different stimulation techniques of visual evoked potentials (VEP) are described. VEP can provide information about neurological function during anaesthesia, surgery and in the unconscious patient after head injury. The feasibility of the method for intraoperative monitoring in neuro- and cardiac surgery and the influence of general anaesthetics and other contributing factors such as temperature, paCO2, pO2, part are discussed.

  9. Changes in middle latency auditory evoked potentials during meditation.

    PubMed

    Telles, Shirley; Naveen, K V

    2004-04-01

    In the present study of middle latency auditory evoked potentials during Brahmakumaris Raja Yoga meditation there was a decrease in the peak latency of the Na wave (a negative wave between 14 and 19 msec.) during meditation. Since the neural generator of this wave lies at the midbrain-thalamic level, from the results one can infer that the meditation reduces conduction time at this level.

  10. 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

  11. Effect of musical modelling on late auditory evoked potentials.

    PubMed

    Paulus, W

    1988-01-01

    Late auditory evoked potentials were recorded in four subjects during musical tasks. A PDP 12 computer synchronized stimuli, which were produced by an integrated circuit, and recording with the help of a quartz time basis. The content of each experiment was different modelling of an ambiguous identical acoustic stimulus. In experiment 1, subjects had to model a 6-note melody according to the classic metric foot. In experiment 2, segmentation of an 8-note melody into 5- and 3- versus 3- and 5-tone motifs had to be performed. In experiment 1 an intra-individually reliable, but inter-individually variable neurophysiological correlate was detected during the heavy tone: (1) positivity, (2) negativity, (3) alpha blocking and (4) DC shift. Experiment 2 yielded an intra- and inter-individually reliable positive DC shift of about 4 microV between the two motifs. Myogenic, ocular, dermal, respiratory or electrocardiographic artefacts were excluded in each case. The results indicate that conclusions from evoked potentials to musical perception might be possible and that possible modelling mechanisms with subsequent undesirable influence on recordings have to be considered in any kind of evoked potential experimental design. PMID:3169066

  12. 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.

  13. 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.

  14. Is the movement-evoked potential mandatory for movement execution? A high-resolution EEG study in a deafferented patient.

    PubMed

    Kristeva, Rumyana; Chakarov, Vihren; Wagner, Michael; Schulte-Mönting, Jürgen; Hepp-Reymond, M-C

    2006-06-01

    During simple self-paced index finger flexion with and without visual feedback of the finger, we compared the movement-evoked potentials of the completely deafferented patient GL with those of 7 age-matched healthy subjects. EEG was recorded from 58 scalp positions, together with the electromyogram (EMG) from the first dorsal interosseous muscle and the movement trace. We analyzed the movement parameters and the contralateral movement-evoked potential and its source. The patient performed the voluntary movements almost as well as the controls in spite of her lack of sensory information from the periphery. In contrast, the movement-evoked potential was observed only in the controls and not in the patient. These findings clearly demonstrate that the movement-evoked potential reflects cutaneous and proprioceptive feedback from the moving part of the body. They also indicate that in absence of sensory peripheral input the motor control switches from an internal "sensory feedback-driven" to a "feedforward" mode. The role of the sensory feedback in updating the internal models and of the movement-evoked potential as a possible cortical correlate of motor awareness is discussed.

  15. 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

  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. Neuronal generators of the visual evoked potentials: intracerebral recording in awake humans.

    PubMed

    Ducati, A; Fava, E; Motti, E D

    1988-01-01

    Flash and pattern reversal visual evoked potentials were recorded in awake patients undergoing stereotactic procedures for severe dyskinetic disorders resistant to medical treatment. The nucleus ventralis lateralis thalami was reached via an occipital approach. VEPs were recorded on the scalp at the entrance of the intracerebral electrode, and serially from sites at different depths. A polarity reversal of the surface recorded wave form took place as the intracerebral electrode was advanced beneath the surface cortical layers. As concerns F-VEPs, most of the scalp activity mirrored the potentials recorded down to the depth of 70-65 mm from the thalamus. The largest amplitude of intracerebral F-VEPs was obtained from recording sites at 50-70 mm from the thalamus, i.e., in the depth of the calcarine fissure. A negative wave, peaking around 47-50 msec, became evident in recording sites at 30-40 mm from the thalamus but vanished as the electrode was advanced farther. In only one patient could we record a small negative wave, peaking at 33 msec, in the vicinity of the corpus geniculatum externum. Furthermore, the oscillatory activity recorded from the scalp appeared to be generated in the cortical layers. PR-VEPs also underwent polarity reversal as the electrode traversed the cortex. PR-VEPs disappeared more superficially than F-VEPs. No PR-evoked activity could be recorded in the vicinity of the corpus geniculatum externum. We conclude that slow and fast components of VEPs recorded from the scalp are entirely generated in cortical layers.

  18. 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

  19. Baroreceptor activation attenuates attentional effects on pain-evoked potentials.

    PubMed

    Gray, Marcus A; Minati, Ludovico; Paoletti, Giulia; Critchley, Hugo D

    2010-12-01

    Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. To address this hypothesis, we explored in a group of healthy participants the combined effects of cue-induced expectancy and baroreceptor activity on the amplitude of pain-evoked ERPs. Brief nociceptive skin stimuli were delivered during a simple visual task; half were preceded by a visual forewarning cue, and half were unpredictable. Nociceptive stimuli were timed to coincide either with systole (maximum activation of cardiac baroreceptors) or with diastole (minimum baroreceptor activation). We observed a strong interaction between expectancy and cardiac timing for the amplitude of the P2 ERP component; no effects were observed for the N2 component. Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive-affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain.

  20. 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

  1. 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

  2. Laminar profile of spontaneous and evoked theta: Rhythmic modulation of cortical processing during word integration.

    PubMed

    Halgren, Eric; Kaestner, Erik; Marinkovic, Ksenija; Cash, Sydney S; Wang, Chunmao; Schomer, Donald L; Madsen, Joseph R; Ulbert, Istvan

    2015-09-01

    Theta may play a central role during language understanding and other extended cognitive processing, providing an envelope for widespread integration of participating cortical areas. We used linear microelectrode arrays in epileptics to define the circuits generating theta in inferotemporal, perirhinal, entorhinal, prefrontal and anterior cingulate cortices. In all locations, theta was generated by excitatory current sinks in middle layers which receive predominantly feedforward inputs, alternating with sinks in superficial layers which receive mainly feedback/associative inputs. Baseline and event-related theta were generated by indistinguishable laminar profiles of transmembrane currents and unit-firing. Word presentation could reset theta phase, permitting theta to contribute to late event-related potentials, even when theta power decreases relative to baseline. Limited recordings during sentence reading are consistent with rhythmic theta activity entrained by a given word modulating the neural background for the following word. These findings show that theta occurs spontaneously, and can be momentarily suppressed, reset and synchronized by words. Theta represents an alternation between feedforward/divergent and associative/convergent processing modes that may temporally organize sustained processing and optimize the timing of memory formation. We suggest that words are initially encoded via a ventral feedforward stream which is lexicosemantic in the anteroventral temporal lobe; its arrival may trigger a widespread theta rhythm which integrates the word within a larger context. PMID:25801916

  3. Laminar profile of spontaneous and evoked theta: Rhythmic modulation of cortical processing during word integration.

    PubMed

    Halgren, Eric; Kaestner, Erik; Marinkovic, Ksenija; Cash, Sydney S; Wang, Chunmao; Schomer, Donald L; Madsen, Joseph R; Ulbert, Istvan

    2015-09-01

    Theta may play a central role during language understanding and other extended cognitive processing, providing an envelope for widespread integration of participating cortical areas. We used linear microelectrode arrays in epileptics to define the circuits generating theta in inferotemporal, perirhinal, entorhinal, prefrontal and anterior cingulate cortices. In all locations, theta was generated by excitatory current sinks in middle layers which receive predominantly feedforward inputs, alternating with sinks in superficial layers which receive mainly feedback/associative inputs. Baseline and event-related theta were generated by indistinguishable laminar profiles of transmembrane currents and unit-firing. Word presentation could reset theta phase, permitting theta to contribute to late event-related potentials, even when theta power decreases relative to baseline. Limited recordings during sentence reading are consistent with rhythmic theta activity entrained by a given word modulating the neural background for the following word. These findings show that theta occurs spontaneously, and can be momentarily suppressed, reset and synchronized by words. Theta represents an alternation between feedforward/divergent and associative/convergent processing modes that may temporally organize sustained processing and optimize the timing of memory formation. We suggest that words are initially encoded via a ventral feedforward stream which is lexicosemantic in the anteroventral temporal lobe; its arrival may trigger a widespread theta rhythm which integrates the word within a larger context.

  4. 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.

  5. 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…

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. Quantifying interhemispheric symmetry of somatosensory evoked potentials with the intraclass correlation coefficient.

    PubMed

    van de Wassenberg, Wilma J G; van der Hoeven, Johannes H; Leenders, Klaus L; Maurits, Natasha M

    2008-06-01

    Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in cortical sensory processing. We developed and evaluated a new technique to quantify interhemispheric SEP symmetry that uses a time interval including multiple SEP components, measures similarity of SEP waveforms between both hemispheres and results in high symmetry values even in the presence of small interhemispheric anatomic differences. Median nerve SEPs were recorded in 50 healthy subjects (20-70 years) using 128-channel EEG. Symmetry was quantified by the intraclass correlation coefficient and correlation coefficient between global field power of left and right median nerve SEPs. In 74% of subjects left-right intraclass correlation coefficient was higher than 0.60, implying high SEP hemispheric symmetry in terms of shape and amplitude. Left-right intraclass correlation coefficients lower than 0.60 were due to differences in amplitude, unilateral absence of peaks, or shape differences. We quantified SEP waveform interhemispheric symmetry and found it to be high in most healthy subjects. This technique may therefore be useful for detection of unilateral abnormalities in cortical sensory processing.

  12. 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

  13. A joint sparse representation-based method for double-trial evoked potentials estimation.

    PubMed

    Yu, Nannan; Liu, Haikuan; Wang, Xiaoyan; Lu, Hanbing

    2013-12-01

    In this paper, we present a novel approach to solving an evoked potentials estimating problem. Generally, the evoked potentials in two consecutive trials obtained by repeated identical stimuli of the nerves are extremely similar. In order to trace evoked potentials, we propose a joint sparse representation-based double-trial evoked potentials estimation method, taking full advantage of this similarity. The estimation process is performed in three stages: first, according to the similarity of evoked potentials and the randomness of a spontaneous electroencephalogram, the two consecutive observations of evoked potentials are considered as superpositions of the common component and the unique components; second, making use of their characteristics, the two sparse dictionaries are constructed; and finally, we apply the joint sparse representation method in order to extract the common component of double-trial observations, instead of the evoked potential in each trial. A series of experiments carried out on simulated and human test responses confirmed the superior performance of our method.

  14. A New Measure for Monitoring Intraoperative Somatosensory Evoked Potentials

    PubMed Central

    Jin, Seung-Hyun; Kim, Jeong Eun; Choi, Young Doo

    2014-01-01

    Objective To propose a new measure for effective monitoring of intraoperative somatosensory evoked potentials (SEP) and to validate the feasibility of this measure for evoked potentials (EP) and single trials with a retrospective data analysis study. Methods The proposed new measure (hereafter, a slope-measure) was defined as the relative slope of the amplitude and latency at each EP peak compared to the baseline value, which is sensitive to the change in the amplitude and latency simultaneously. We used the slope-measure for EP and single trials and compared the significant change detection time with that of the conventional peak-to-peak method. When applied to single trials, each single trial signal was processed with optimal filters before using the slope-measure. In this retrospective data analysis, 7 patients who underwent cerebral aneurysm clipping surgery for unruptured aneurysm middle cerebral artery (MCA) bifurcation were included. Results We found that this simple slope-measure has a detection time that is as early or earlier than that of the conventional method; furthermore, using the slope-measure in optimally filtered single trials provides warning signs earlier than that of the conventional method during MCA clipping surgery. Conclusion Our results have confirmed the feasibility of the slope-measure for intraoperative SEP monitoring. This is a novel study that provides a useful measure for either EP or single trials in intraoperative SEP monitoring. PMID:25628803

  15. 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.

  16. Evaluation of spinal cord function by means of lower limb somatosensory evoked potentials in reparative aortic surgery.

    PubMed

    Fava, E; Bortolani, E M; Ducati, A; Ruberti, U

    1988-01-01

    A group of patients undergoing aortic replacement of thoracic and abdominal aneurysms were studied by intraoperative recording of Somatosensory Evoked Potentials (SEPs). Lower limb nerves were stimulated and SEPs recorded at spinal and cortical level. Progressive changes of cortical SEPs until their disappearance were observed. In operations on the thoracic aorta, the spinal response was essentially unmodified, so that the observed alterations reflected true dysfunction of the spinal cord. The only patient who developed an intraoperative anterior spinal infarct had the longest period of absent SEPs and a striking latency prolongation when they returned. Postoperative recordings were absolutely normal. When the abdominal aorta was occluded, SEP alterations involved both cortical and spinal responses, so that it is difficult to distinguish between the relative roles of peripheral nerve and spinal cord ischemia. These findings indicate that SEPs can be reliably applied to spinal cord monitoring in the course of aortic surgery, even though they are mainly conducted in the posterior cord tracts.

  17. [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

  18. [Decrease of latency of auditory evoked potentials in humans practicing transcendental meditation (author's transl].

    PubMed

    Wandhöfer, A; Kobal, G; Plattig, K H

    1976-06-01

    Slow cortical auditory responses were recorded from humans practicing transcendental meditation. The potentials were computated according to Fig. 1, and the latencies of the positive peaks P1 and P2 and of the negative peaks N1 and N2 were measured as well as the areas of the on-effect FON, of the off-effect FOFF and of the DC-shift FDC during the stimulus duration. Latencies for most of the initial peaks during TM as well as during normal consciousness were significantly shorter than in a control group in a dozing state or during normal consciousness (Table 1 and Fig. 2). Certain differences were also found in regard to other parameters such as amplitudes and areas of the auditory evoked response.

  19. [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

  20. Visual evoked potential monitoring of optic nerve function during surgery.

    PubMed

    Harding, G F; Bland, J D; Smith, V H

    1990-10-01

    A study was made with intra-operative flash--visual evoked potentials (VEP) monitored using a fibre-optic/contact lens photo stimulator in 57 patients undergoing intra-orbital surgical procedures with potential risk to the optic nerve. The VEPs recorded under enflurane and nitrous oxide anaesthesia did not differ significantly in latency or amplitude from the pre-operative recordings. Transient abolition of the VEP was seen under many circumstances and did not correlate with the outcome of surgery, but absence of a previously normal VEP for more than four minutes during surgical manipulation within the orbit did show a correlation with post operative impairment of vision. The technique provides early warning to the surgeon of threats to the integrity of the optic nerve.

  1. Visual evoked potential monitoring of optic nerve function during surgery.

    PubMed Central

    Harding, G F; Bland, J D; Smith, V H

    1990-01-01

    A study was made with intra-operative flash--visual evoked potentials (VEP) monitored using a fibre-optic/contact lens photo stimulator in 57 patients undergoing intra-orbital surgical procedures with potential risk to the optic nerve. The VEPs recorded under enflurane and nitrous oxide anaesthesia did not differ significantly in latency or amplitude from the pre-operative recordings. Transient abolition of the VEP was seen under many circumstances and did not correlate with the outcome of surgery, but absence of a previously normal VEP for more than four minutes during surgical manipulation within the orbit did show a correlation with post operative impairment of vision. The technique provides early warning to the surgeon of threats to the integrity of the optic nerve. PMID:2266371

  2. 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...

  3. Auditory evoked-potential correlates of decrement detection.

    PubMed

    Boettcher, Flint A; Emery, Mark

    2006-02-01

    Decrement detection is a commonly used psychophysical technique in which a subject is required to detect partially filled gaps in an ongoing sound. The paradigm provides information regarding both temporal resolution and intensity discrimination. The purpose of this project was to determine if an evoked-potential paradigm using decrements in an ongoing noise approximates psychophysical data. If so, the evoked-response paradigm would be useful in estimating decrement detection in laboratory animals, where training time for a psychophysical model of decrement detection might prove prohibitive. In this study, Mongolian gerbils aged 3-10 months were used as subjects. The stimulus was a broadband noise (low-pass filtered at 5 or 30 kHz, overall level of 70 dB SPL), interrupted for durations of 2-32 ms. Within each off period, a second, identically filtered noise at levels of 0-70 dB SPL was presented. In a manner qualitatively similar to previous human and animal psychophysical studies, the ABR threshold decreased as the duration of the decrement was increased. Latency and amplitudes changed as a function of decrement duration when the decrement depth was held constant, but minimal change as a function of decrement depth occurred when the decrement duration was held constant. The results suggest that ABR paradigm for decrement detection is a qualitative alternative to psychophysical techniques, but that amplitude and latency data may not provide more information on temporal and intensity coding than ABR measures of gap detection. PMID:16403610

  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. TMS-induced motor evoked potentials in Wilson's disease: a systematic literature review.

    PubMed

    Bembenek, Jan P; Kurczych, Katarzyna; Członkowska, Anna

    2015-04-01

    Wilson's disease (WD) is a metabolic brain disease resulting from improper copper metabolism. Although pyramidal symptoms are rarely observed, subclinical injury is highly possible as copper accumulates in all brain structures. The usefulness of motor evoked potentials (MEPs) in pyramidal tracts damage evaluation still appears to be somehow equivocal. We searched for original papers assessing the value of transcranial magnetic stimulation elicited MEPs with respect to motor function of upper and lower extremity in WD. We searched PubMed for original papers evaluating use of MEPs in WD using key words: "motor evoked potentials Wilson's disease" and "transcranial magnetic stimulation Wilson's disease." We found six articles using the above key words. One additional article and one case report were found while viewing the references lists. Therefore, we included eight studies. Number of patients in studies was low and their clinical characteristic was variable. There were also differences in methodology. Abnormal MEPs were confirmed in 20-70% of study participants. MEPs were not recorded in 7.6-66.7% of patients. Four studies reported significantly increased cortical excitability (up to 70% of patients). Prolonged central motor conduction time was observed in four studies (30-100% of patients). One study reported absent or prolonged central motor latency in 66.7% of patients. Although MEPs may be abnormal in WD, this has not been thoroughly assessed. Hence, further studies are indispensable to evaluate MEPs' usefulness in assessing pyramidal tract damage in WD.

  6. Modeling neural correlates of auditory attention in evoked potentials using corticothalamic feedback dynamics.

    PubMed

    Trenado, Carlos; Haab, Lars; Strauss, Daniel J

    2007-01-01

    Auditory evoked cortical potentials (AECP) are well established as diagnostic tool in audiology and gain more and more impact in experimental neuropsychology, neuro-science, and psychiatry, e.g., for the attention deficit disorder, schizophrenia, or for studying the tinnitus decompensation. The modulation of AECP due to exogenous and endogenous attention plays a major role in many clinical applications and has experimentally been studied in neuropsychology. However the relation of corticothalamic feedback dynamics to focal and non-focal attention and its large-scale effect reflected in AECPs is far from being understood. In this paper, we model neural correlates of auditory attention reflected in AECPs using corticothalamic feedback dynamics. We present a mapping of a recently developed multiscale model of evoked potentials to the hearing path and discuss for the first time its neurofunctionality in terms of corticothalamic feedback loops related to focal and non-focal attention. Our model reinforced recent experimental results related to online attention monitoring using AECPs with application as objective tinnitus decompensation measure. It is concluded that our model presents a promising approach to gain a deeper understanding of the neurodynamics of auditory attention and might be use as an efficient forward model to reinforce hypotheses that are obtained from experimental paradigms involving AECPs. PMID:18002948

  7. 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

  8. 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

  9. Aroused with heart: Modulation of heartbeat evoked potential by arousal induction and its oscillatory correlates.

    PubMed

    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

  10. Visual evoked potentials in neuromyelitis optica and its spectrum disorders.

    PubMed

    Ringelstein, Marius; Kleiter, Ingo; Ayzenberg, Ilya; Borisow, Nadja; Paul, Friedemann; Ruprecht, Klemens; Kraemer, Markus; Cohn, Eva; Wildemann, Brigitte; Jarius, Sven; Hartung, Hans-Peter; Aktas, Orhan; Albrecht, Philipp

    2014-04-01

    Optic neuritis (ON) is a key feature of neuromyelitis optica (NMO). Recently, NMO patients of predominantly Afro-Brazilian origin were evaluated by visual evoked potentials (VEPs) and showed marked amplitude reductions. Here, we analyzed VEPs in a predominantly Caucasian cohort, consisting of 43 patients with definite NMO, 18 with anti-aquaporin (AQP) 4 antibody-seropositive NMO spectrum disorders and 61 matched healthy controls. We found reduced amplitudes in only 12.3%, prolonged latencies in 41.9% and a lack of response in 14.0% of NMO eyes. Delayed P100 latencies in eyes without prior ON suggested this was a subclinical affection. The data indicate heterogenous patterns in NMO, warranting further investigation.

  11. Diurnal changes in the rabbit's visual evoked potential.

    PubMed

    Bobbert, A C; Krul, W H; Brandenburg, J

    1978-01-01

    Rabbits that have been exposed to the natural cycles of day and night exhibit marked diurnal changes in the shape of their Visual Evoked Potential in constant environmental conditions. The results of exposure to artificial 24 hr light-dark cycles strongly suggest that it is the regular alternation of daylight and darkness which acts as the synchronizing "Zeitgeber" for the V.E.P. rhythm which exists after exposure to the natural cycles of day and night. It would seem further that the V.E.P. changes reflect a square-wave like rhythm in the sensitivity of the visual system to photic stimuli, in which the sensitivity is much higher at night than in the day-time. The probable importance of the diurnal V.E.P. rhythm for the occurrence of daily fluctuations in behaviour is discussed. PMID:563382

  12. 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

  13. Pattern-reversal visual evoked potentials in phenylketonuric children.

    PubMed

    Landi, A; Ducati, A; Villani, R; Longhi, R; Riva, E; Rodocanachi, C; Giovannini, M

    1987-01-01

    Pattern-reversal visual evoked potentials (PR-VEPs) and EEG were recorded in 14 phenylketonuric (PKU) children on a low-phenylalanine (phe) diet; the data obtained were correlated with metabolic parameters, namely, the actual phe plasma level, the mean phe plasma level in the last year, an the beginning of the diet. PR-VEPs seem to be more sensitive than EEG in detecting neurophysiological derangements in these subjects; in fact PR-VEPs were pathological in six patients while EEG detected three; no significant alterations were found in the neurophysiological tests among the children with good metabolic control, and only one child was abnormal among the six on an early dietetic regimen; in contrast, six of the nine subjects presenting with high mean phe plasma levels (greater than 10 mg/100 ml) and five of the eight whose diet started after the 2nd month of life showed pathological PR-VEPs.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. Activity-dependent potentiation and depression of visual cortical responses to optic nerve stimulation in kittens.

    PubMed

    Tamura, H; Tsumoto, T; Hata, Y

    1992-11-01

    1. To see whether long-lasting changes in synaptic efficacy are induced in the developing visual cortex (VC), field potentials evoked by test stimulation given alternatively to each of the optic nerves (ONs) were recorded from VC of kittens ranging in age from 4 to 8 wk. In some experiments, field potentials were recorded simultaneously from the dorsal lateral geniculate nucleus (LGN) in addition to VC. 2. Tetanic stimulation was applied to one of the ONs for 1-60 min at 5 Hz. Homosynaptic potentiation of cortical responses, defined as an increase lasting > 2.5 h in the cortical field potential evoked by test stimulation of the ON that was tetanized, was induced without any changes in LGN responses in 3 of the 12 kittens tested. Heterosynaptic depression, defined as a decrease lasting > 0.5 h in the field potential evoked by stimulation of the ON that was not tetanized, was also induced in two of those three kittens. 3. To elucidate a role of inputs originating from spontaneous activity of retinal ganglion cells in induction of potentiation and depression in the cortex, tetrodotoxin (TTX) was injected into both eyes of 11 kittens. After we confirmed the suppression of retinal activity by TTX, tetanic stimulation was applied to ON. Homosynaptic potentiation of cortical responses was induced in 6 of the 11 kittens, and the ratio of the mean amplitude of posttetanic responses to that of pretetanic responses for the 11 kittens was on average larger than that for the 12 control kittens. Heterosynaptic depression was not observed in any of the 11 kittens. 4. To see a role of postsynaptic activity in induction of potentiation and depression, gamma-aminobutyric acid (GABA) was applied continuously to the VC by an infusion pump in 10 kittens. Tetanic stimulation was given to ON while cortical activities were suppressed by GABA. After recovery of cortical activities, homosynaptic depression was found to be induced in 3 of the 10 kittens, but homosynaptic potentiation was not

  20. 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

  1. 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

  2. Evoked potential correlates of intelligence: some problems with Hendrickson's string measure of evoked potential complexity and error theory of intelligence.

    PubMed

    Vetterli, C F; Furedy, J J

    1985-07-01

    The string measure of evoked potential (EP) complexity is based on a new error theory of intelligence, which differs from the older speed-based formulations which focus on EP latency rather than complexity. In this note we first raise a methodological problem of arbitrariness with respect to one version of the string measure. We then provide a comparative empirical assessment of EP-IQ correlations with respect to a revised string measure (which does not suffer from the methodological problem), a latency measure, and another measure of EP complexity: average voltage. This assessment indicates that the string measure, in particular, yields quite disorderly results, and that, in general, the results favor the speed over the error formulation.

  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.

  4. 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

  5. Vestibular evoked myogenic potentials in patients with ankylosing spondylitis.

    PubMed

    Özgür, Abdulkadir; Serdaroğlu Beyazal, Münevver; Terzi, Suat; Coşkun, Zerrin Özergin; Dursun, Engin

    2016-10-01

    Ankylosing spondylitis (AS) is a chronic systemic inflammatory disease with unknown etiology. Although sacroiliac joint involvement is the classic sign along with the formed immune mediators, it may result in immune-mediated inner ear disease and may cause damage to the audiovestibular system. Vestibular evoked myogenic potentials (VEMP) is a clinical reflex test used in the diagnosis of vestibular diseases and is performed by recording and evaluating the muscle potentials resulting from the stimulation of the vestibular system with different stimuli. The aim of this study is to evaluate the cervical VEMP test results in AS patients without vestibular symptoms. Thirty-three patients with AS and a control group of 30 healthy volunteers with similar demographic characteristics were evaluated in the study. VEMP wave latency, P13-N23 wave amplitude, and VEMP asymmetry ratio (VAR) values were compared between the groups. The relationship between clinical and laboratory findings of the AS patients and VEMP data were also investigated. Compared with healthy people, this study shows the response rate of patients with ankylosing spondylitis was reduced in the VEMP test, and P13-N23 wave amplitude showed a decrease in AS patients who had VEMP response (p < 0.001). There was no correlation between the clinical and laboratory findings and VEMP findings in patients with ankylosing spondylitis. The data obtained from this study suggest that AS may lead to decreased sensitivity of the vestibular system.

  6. Influence of visual angle on pattern reversal visual evoked potentials

    PubMed Central

    Kothari, Ruchi; Singh, Smita; Singh, Ramji; Shukla, A. K.; Bokariya, Pradeep

    2014-01-01

    Purpose: The aim of this study was to find whether the visual evoked potential (VEP) latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs). Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females) in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females) in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field) on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II). The statistical analysis was done by One Way Analysis of Variance (ANOVA) using EPI INFO 6. Results: In Group I, the maximum (max.) P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes. Conclusion: Altering the size of stimulus (visual angle) has an effect on the PRVEP parameters. Our study found that the 120 is the

  7. 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

  8. The I' potential of the brain-stem auditory-evoked potential.

    PubMed

    Moore, E J; Semela, J J; Rakerd, B; Robb, R C; Ananthanarayan, A K

    1992-01-01

    We have consistently recorded a positive wave which precedes wave I, and is called I', within the human brain-stem auditory-evoked potential. It is postulated that I' represents initial neural activity of the auditory nerve, which presumably has as its origin auditory nerve dendrites. Thus, I' may represent a summed far-field dendritic potential from currents of excitatory postsynaptic potentials. We report latency and amplitude values of I'.

  9. 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

  10. Brain-stem evoked potentials and noise effects in seagulls.

    PubMed

    Counter, S A

    1985-01-01

    Brain-stem auditory evoked potentials (BAEP) recorded from the seagull were large-amplitude, short-latency, vertex-positive deflections which originate in the eighth nerve and several brain-stem nuclei. BAEP waveforms were similar in latency and configurations to that reported for certain other lower vertebrates and some mammals. BAEP recorded at several pure tone frequencies throughout the seagull's auditory spectrum showed an area of heightened auditory sensitivity between 1 and 3 kHz. This range was also found to be the primary bandwidth of the vocalization output of young seagulls. Masking by white noise and pure tones had remarkable effects on several parameters of the BAEP. In general, the tone- and click-induced BAEP were either reduced or obliterated by both pure tone and white noise maskers of specific signal to noise ratios and high intensity levels. The masking effects observed in this study may be related to the manner in which seagulls respond to intense environmental noise. One possible conclusion is that intense environmental noise, such as aircraft engine noise, may severely alter the seagull's localization apparatus and induce sonogenic stress, both of which could cause collisions with low-flying aircraft.

  11. Brain-stem auditory evoked potentials and brain death.

    PubMed

    Machado, C; Valdés, P; García-Tigera, J; Virues, T; Biscay, R; Miranda, J; Coutin, P; Román, J; García, O

    1991-01-01

    BAEP records were obtained from 30 brain-dead patients. Three BAEP patterns were observed: (1) no identifiable waves (73.34%), (2) an isolated bilateral wave I (16.66%), and (3) an isolated unilateral wave I (10%). When wave I was present, it was always significantly delayed. Significant augmentation of wave I amplitude was present bilaterally in one case and unilaterally in another. On the other hand, in serial records from 3 cases wave I latency tended to increase progressively until this component disappeared. During the same period, wave I amplitude fluctuations were observed. A significant negative correlation was found for wave I latency with heart rate and body temperature in 1 case. Two facts might explain the progressive delay and disappearance of wave I in brain-dead patients: a progressive hypoxic-ischaemic dysfunction of the cochlea and the eighth nerve plus hypothermia, often present in brain-dead patients. Then the incidence of wave I preservation reported by different authors in single BAEP records from brain-dead patients might depend on the moment at which the evoked potential study was done in relation to the onset of the clinical state. It is suggested that, although BAEPs provide an objective electrophysiological assessment of brain-stem function, essential for BD diagnosis, this technique could be of no value for this purpose when used in isolation.

  12. Visual evoked potentials in guinea pigs with brain lesion.

    PubMed

    Takeuchi, T; Suzuki, M; Sitizyo, K; Isobe, R; Saito, T; Umemura, T; Shimada, A

    1992-10-01

    Visual evoked potentials (VEPs) were recorded in 10 adult male guinea pigs with brain lesion. Lesions were produced in 5 animals by superficial suction of the occipital lobe. The other 5 animals were orally administered with hexachlorophene (about 35 mg/kg/day) for 28 days. In the VEP following the ablation of the occipital lobe, the peaks P10, N20, P55, N75, N140 and P200 disappeared in many cases. The amplitude of the peak N40 decreased to approximately one half its control VEP. In the VEP obtained from the animals administered with hexachlorophene, the peak latencies of N20, P30, P55, N75 and P100 were slightly prolonged after the 7th day following the first administration. On the other hand, there was no change in the latency of N40 during the whole period of administration. The peak-to-peak amplitude showed some variability in different peaks. Histologically, diffuse status spongiosis were found in the white matter of the cerebrum, cerebellum, and brain stem. As described above, the ablation of the occipital lobe caused markedly depressed VEPs, however, the responses to the photic stimulation persisted after the injury. On the other hand, the VEPs of animals administered with hexachlorophene showed a high probability of peak appearance, and a decrease in amplitude was not marked.

  13. Auditory Evoked Potential Variability in Healthy and Schizophrenia Subjects

    PubMed Central

    Jansen, Ben H.; Hu, Lingli; Boutros, Nash N.

    2010-01-01

    Objectives To investigate if the reduced P50, N100 and P200 auditory evoked potential (EP) components and gating deficits seen in schizophrenia can be explained in terms of response incompleteness. Methods Twenty-five healthy and schizophrenia participants were studied using pairs of 1000 Hz tones (S1 and S2, 0.5 s apart) separated by 8.0 s. A correlation-based clustering method identified the responses containing P50, N100, and/or P200 related-activity. Results Schizophrenia participants produced fewer S1 and S2 responses containing all three EP components than healthy participants. Healthy participants, but not the patient population, produced fewer and smaller S2 than S1 responses containing all three EP components. However, the S2 responses following complete S1 responses were smaller than the complete S1 responses in both populations. Conclusions The gating deficits observed in schizophrenia are due to two mechanisms. First, the S1 response consistency is less in schizophrenia than in health. Second, the S2 responses are attenuated less in schizophrenia. Significance This research contributes to the understanding of response variability and sensory gating in health and schizophrenia. It also extends previous reports that fewer and smaller P300 components are produced in schizophrenia than in health to the mid-latency component range. PMID:20363180

  14. Effects of meditation on brainstem auditory evoked potentials.

    PubMed

    McEvoy, T M; Frumkin, L R; Harkins, S W

    1980-01-01

    Brainstem auditory evoked potentials (BAEPs) were measured in five advanced practitioners of Transcendental Meditation (TM) to determine whether such responses would reflect reported increases in perceptual acuity to auditory stimuli following meditation. The BAEP provides an objective physiological index of auditory function at a subcortical level. Repeated measures of the BAEPs of TM practitioners were taken before and after a period of meditation and were compared with those of age-matched controls. Peak latencies as well as interwave latencies between major BAEP components were evaluated. No pre-postmeditation differences for experimental subjects were observed at low stimulus intensities (0--35 dB). At moderate intensities (40--50 dB), latency of the inferior collicular wave (wave V) increased following meditation, but at higher stimulus intensities (55--70 dB), latency of this wave was slightly decreased. Comparison of slopes and intercepts of stimulus intensity-latency functions indicates a possible effect of meditation on brainstem activity.

  15. 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

  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. 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

  18. 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

  19. 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

  20. 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

  1. A Chronic Implant to Record Electroretinogram, Visual Evoked Potentials and Oscillatory Potentials in Awake, Freely Moving Rats for Pharmacological Studies

    PubMed Central

    Guarino, Irene; Loizzo, Stefano; Lopez, Luisa; Fadda, Antonello; Loizzo, Alberto

    2004-01-01

    Electroretinogram (ERG), widely used to study the pharmacological effects of drugs in animal models (e.g., diabetic retinopathy), is usually recorded in anesthetized rats. We report here a novel simple method to obtain chronic implantation of electrodes for simultaneous recording at the retinal and cortical levels in freely moving, unanesthetized animals. We recorded cortical (VEPs) and retinal (ERGs) responses evoked by light (flash) stimuli in awake rats and compared the results in the same rats anesthetized with urethane (0.6 mg/kg) before and after the monocular administration of scopolamine methyl bromide (1‰solution). We also compared the retinal responses with those derived from a classic acute corneal electrode. Anesthesia induced consistent changes of several VEP and ERG parameters like an increase of both latency and amplitude. In particular, the analysis of the variation of latency, amplitude, and spectral content of rapid oscillatory potentials could be important for a functional evaluation of the visual system in unanesthetized versus anesthetized animals. PMID:15656271

  2. Accurate identification of waveform of evoked potentials by component decomposition using discrete cosine transform modeling.

    PubMed

    Bai, O; Nakamura, M; Kanda, M; Nagamine, T; Shibasaki, H

    2001-11-01

    This study introduces a method for accurate identification of the waveform of the evoked potentials by decomposing the component responses. The decomposition was achieved by zero-pole modeling of the evoked potentials in the discrete cosine transform (DCT) domain. It was found that the DCT coefficients of a component response in the evoked potentials could be modeled sufficiently by a second order transfer function in the DCT domain. The decomposition of the component responses was approached by using partial expansion of the estimated model for the evoked potentials, and the effectiveness of the decomposition method was evaluated both qualitatively and quantitatively. Because of the overlap of the different component responses, the proposed method enables an accurate identification of the evoked potentials, which is useful for clinical and neurophysiological investigations.

  3. Steady-state evoked potentials to study the processing of tactile and nociceptive somatosensory input in the human brain.

    PubMed

    Colon, E; Legrain, V; Mouraux, A

    2012-10-01

    The periodic presentation of a sensory stimulus induces, at certain frequencies of stimulation, a sustained electroencephalographic response of corresponding frequency, known as steady-state evoked potentials (SS-EP). In visual, auditory and vibrotactile modalities, studies have shown that SS-EP reflect mainly activity originating from early, modality-specific sensory cortices. Furthermore, it has been shown that SS-EP have several advantages over the recording of transient event-related brain potentials (ERP), such as a high signal-to-noise ratio, a shorter time to obtain reliable signals, and the capacity to frequency-tag the cortical activity elicited by concurrently presented sensory stimuli. Recently, we showed that SS-EP can be elicited by the selective activation of skin nociceptors and that nociceptive SS-EP reflect the activity of a population of neurons that is spatially distinct from the somatotopically-organized population of neurons underlying vibrotactile SS-EP. Hence, the recording of SS-EP offers a unique opportunity to study the cortical representation of nociception and touch in humans, and to explore their potential crossmodal interactions. Here, (1) we review available methods to achieve the rapid periodic stimulation of somatosensory afferents required to elicit SS-EP, (2) review previous studies that have characterized vibrotactile and nociceptive SS-EP, (3) discuss the nature of the recorded signals and their relationship with transient event-related potentials and (4) outline future perspectives and potential clinical applications of this technique.

  4. Neural origin of evoked potentials during thalamic deep brain stimulation.

    PubMed

    Kent, Alexander R; Grill, Warren M

    2013-08-01

    Closed-loop deep brain stimulation (DBS) systems could provide automatic adjustment of stimulation parameters and improve outcomes in the treatment of Parkinson's disease and essential tremor. The evoked compound action potential (ECAP), generated by activated neurons near the DBS electrode, may provide a suitable feedback control signal for closed-loop DBS. The objectives of this work were to characterize the ECAP across stimulation parameters and determine the neural elements contributing to the signal. We recorded ECAPs during thalamic DBS in anesthetized cats and conducted computer simulations to calculate the ECAP of a population of thalamic neurons. The experimental and computational ECAPs were similar in shape and had characteristics that were correlated across stimulation parameters (R(2) = 0.80-0.95, P < 0.002). The ECAP signal energy increased with larger DBS amplitudes (P < 0.0001) and pulse widths (P < 0.002), and the signal energy of secondary ECAP phases was larger at 10-Hz than at 100-Hz DBS (P < 0.002). The computational model indicated that these changes resulted from a greater extent of neural activation and an increased synchronization of postsynaptic thalamocortical activity, respectively. Administration of tetrodotoxin, lidocaine, or isoflurane abolished or reduced the magnitude of the experimental and computational ECAPs, glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D(-)-2-amino-5-phosphonopentanoic acid (APV) reduced secondary ECAP phases by decreasing postsynaptic excitation, and the GABAA receptor agonist muscimol increased the latency of the secondary phases by augmenting postsynaptic hyperpolarization. This study demonstrates that the ECAP provides information about the type and extent of neural activation generated during DBS, and the ECAP may serve as a feedback control signal for closed-loop DBS.

  5. 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

  6. 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

  7. 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

  8. 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

  9. The Nature and Process of Development in Averaged Visually Evoked Potentials: Discussion on Pattern Structure.

    ERIC Educational Resources Information Center

    Izawa, Shuji; Mizutani, Tohru

    This paper examines the development of visually evoked EEG patterns in retarded and normal subjects. The paper focuses on the averaged visually evoked potentials (AVEP) in the central and occipital regions of the brain in eyes closed and eyes open conditions. Wave pattern, amplitude, and latency are examined. The first section of the paper reviews…

  10. 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

  11. Enhanced P1-N1 auditory evoked potential in patients with musicians' cramp.

    PubMed

    Lim, Vanessa K; Bradshaw, John L; Nicholls, Michael E R; Altenmüller, Eckart

    2005-12-01

    Auditory evoked potentials (AEPs) were examined in patients with musician's cramp (focal dystonia) in order to determine whether these patients have electrophysiological changes in a sensory system that is not usually associated with symptoms. All participants were professional guitarists and were required to listen to 2,000 monaurally presented stimuli (middle C, with duration of 7 ms). During one block, 250 stimuli were presented to one ear. Once a block was finished, another block was presented in the other ear; in total there were eight blocks of stimuli. During this task, EEGs from 10 scalp electrodes and one bipolar eye channel were continuously recorded. There were no significant latency or topographical differences in the electrophysiological recordings. However, there was a significant group difference in the peak-to-peak amplitude of the P1-N1a component. The patients had a larger peak-to-peak difference than controls (1.63 vs. 0.62 microV). The P1 and N1a are cortically generated potentials. Patients with focal dystonia had an increase in activity compared to controls when processing simple auditory stimuli. Such changes in electrophysiological responses may be a result of increases in excitation or lack of inhibition; alternatively the changes may represent cross-modal maladaptive plasticity from the somatosensory modality to the auditory modality. Thus, this study provides further evidence that patients with focal dystonia have alterations of the central nervous system that are not limited to their symptomatic sensory domain.

  12. Changes in midlatency auditory evoked potentials following two yoga-based relaxation techniques.

    PubMed

    Subramanya, Pailoor; Telles, Shirley

    2009-07-01

    Practicing meditation while focusing on a sound or a symbol influenced midlatency auditory evoked potentials (MLAEPs). Cyclic meditation (CM) is a technique combining yoga postures with meditation while supine, which has influenced the P300 event-related potential. The effects of CM on MLAEPs have not been previously studied. The MLAEPs were studied before and after the practice of CM compared to an equal duration of supine rest (SR) in 47 male volunteers (group mean age 26.5 +/- 4.4 years), recorded from the vertex referenced to linked earlobes. The sessions were one day apart and subjects were randomly assigned to each session. The Pa wave peak latency and Nb wave peak latency significantly increased following CM compared to before CM (repeated measures ANOVA, post-hoc analysis with least significant difference, p<0.05). There was a significant increase in the peak amplitude of the Nb wave (p<0.05) compared to before CM. Post SR there was a significant increase in the peak latency of the Na wave (p<0.05) compared to before SR. In conclusion following CM the latencies of neural generators corresponding to cortical areas is prolonged, whereas following SR a similar change occurs at mesencephalic-diencephalic levels.

  13. 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.

  14. 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.

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

    PubMed

    Szlavik, Robert B

    2016-02-01

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

  16. 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

  17. Long-latency TMS-evoked potentials during motor execution and inhibition.

    PubMed

    Yamanaka, Kentaro; Kadota, Hiroshi; Nozaki, Daichi

    2013-01-01

    Transcranial magnetic stimulation (TMS) has often been used in conjunction with electroencephalography (EEG), which is effective for the direct demonstration of cortical reactivity and corticocortical connectivity during cognitive tasks through the spatio-temporal pattern of long-latency TMS-evoked potentials (TEPs). However, it remains unclear what pattern is associated with the inhibition of a planned motor response. Therefore, we performed TMS-EEG recording during a go/stop task, in which participants were instructed to click a computer mouse with a right index finger when an indicator that was moving with a constant velocity reached a target (go trial) or to avoid the click when the indicator randomly stopped just before it reached the target (stop trial). Single-pulse TMS to the left (contralateral) or right (ipsilateral) motor cortex was applied 500 ms before or just at the target time. TEPs related to motor execution and inhibition were obtained by subtractions between averaged EEG waveforms with and without TMS. As a result, in TEPs induced by both contralateral and ipsilateral TMS, small oscillations were followed by a prominent negative deflection around the TMS site peaking at approximately 100 ms post-TMS (N100), and a less pronounced later positive component (LPC) over the broad areas that was centered at the midline-central site in both go and stop trials. However, compared to the pattern in go and stop trials with TMS at 500 ms before the target time, N100 and LPC were differently modulated in the go and stop trials with TMS just at the target time. The amplitudes of both N100 and LPC decreased in go trials, while the amplitude of LPC decreased and the latency of LPC was delayed in both go and stop trials. These results suggested that TMS-induced neuronal reactions in the motor cortex and subsequent their propagation to surrounding cortical areas might change functionally according to task demand when executing and inhibiting a motor response.

  18. Nicotinic modulation of auditory evoked potential electroencephalography in a rodent neurodevelopmental model of schizophrenia.

    PubMed

    Kohlhaas, Kathy L; Robb, Holly M; Roderwald, Victoria A; Rueter, Lynne E

    2015-10-15

    Schizophrenia is a chronic disease that has been hypothesized to be linked to neurodevelopmental abnormalities. Schizophrenia patients exhibit impairments in basic sensory processing including sensory gating deficits in P50 and mismatch negativity (MMN). Neuronal nicotinic acetylcholine receptor (nAChR) agonists have been reported to attenuate these deficits. Gestational exposure of rats to methylazoxymethanol acetate (MAM) at embryonic day 17 leads to developmental disruption of the limbic-cortical system. MAM exposed offspring show neuropathological and behavioral changes that have similarities with those seen in schizophrenia. In this study, we aimed to assess whether N40 auditory sensory gating (the rodent form of P50 gating) and MMN deficits as measures of auditory evoked potential (AEP) electroencephalography (EEG) are present in MAM rats and whether nAChR agonists could attend the deficit. E17 male MAM and sham rats were implanted with cortical electrodes at 2 months of age. EEG recordings evaluating N40 gating and MMN paradigms were done comparing effects of vehicle (saline), nicotine and the α7 agonist ABT-107. Deficits were seen for MAM rats compared to sham animals in both N40 auditory sensory gating and MMN AEP recordings. There was a strong trend for N40 deficits to be attenuated by both nicotine (0.16mg/kg i.p. base) and ABT-107 (1.0mg/kg i.p. base). MMN deficits were significantly attenuated by ABT-107 but not by nicotine. These data support the MAM model as a useful tool for translating pharmacodynamic effects in clinical medicine studies of novel therapeutic treatments for schizophrenia. PMID:26032639

  19. Nicotinic modulation of auditory evoked potential electroencephalography in a rodent neurodevelopmental model of schizophrenia.

    PubMed

    Kohlhaas, Kathy L; Robb, Holly M; Roderwald, Victoria A; Rueter, Lynne E

    2015-10-15

    Schizophrenia is a chronic disease that has been hypothesized to be linked to neurodevelopmental abnormalities. Schizophrenia patients exhibit impairments in basic sensory processing including sensory gating deficits in P50 and mismatch negativity (MMN). Neuronal nicotinic acetylcholine receptor (nAChR) agonists have been reported to attenuate these deficits. Gestational exposure of rats to methylazoxymethanol acetate (MAM) at embryonic day 17 leads to developmental disruption of the limbic-cortical system. MAM exposed offspring show neuropathological and behavioral changes that have similarities with those seen in schizophrenia. In this study, we aimed to assess whether N40 auditory sensory gating (the rodent form of P50 gating) and MMN deficits as measures of auditory evoked potential (AEP) electroencephalography (EEG) are present in MAM rats and whether nAChR agonists could attend the deficit. E17 male MAM and sham rats were implanted with cortical electrodes at 2 months of age. EEG recordings evaluating N40 gating and MMN paradigms were done comparing effects of vehicle (saline), nicotine and the α7 agonist ABT-107. Deficits were seen for MAM rats compared to sham animals in both N40 auditory sensory gating and MMN AEP recordings. There was a strong trend for N40 deficits to be attenuated by both nicotine (0.16mg/kg i.p. base) and ABT-107 (1.0mg/kg i.p. base). MMN deficits were significantly attenuated by ABT-107 but not by nicotine. These data support the MAM model as a useful tool for translating pharmacodynamic effects in clinical medicine studies of novel therapeutic treatments for schizophrenia.

  20. Monitoring of brain function by means of evoked potentials in cerebral aneurysm surgery.

    PubMed

    Ducati, A; Landi, A; Cenzato, M; Fava, E; Rampini, P; Giovanelli, M; Villani, R

    1988-01-01

    Deliberate arterial hypotension is currently used to operate upon cerebral aneurysms. However, it is not ascertained whether this practice is really safe for all patients, especially those presenting with preoperative vasospasm. 50 patients, requiring surgical treatment for cerebral aneurysm, have been submitted, during surgery, to the recording of Somatosensory Evoked Potentials (SEPs) on median nerve stimulation. This technique allows the functional evaluation of neural pathways mediating the somatosensory stimuli and of primary somatosensory cortex; it is known that a decrease of cerebral perfusion may affect the SEP waveforms in terms of reduced subcortical conduction velocity (i.e., increased central conduction time, CCT) and of reduced cortical response amplitude. These changes may be apparent before a permanent neurological damage is produced. Preoperative SEP recording demonstrated a prolonged CCT, possibly related to vasospasm, in 9 patients, a normal clinical evaluation notwithstanding (grade I and II). During intraoperative deliberate hypotension, a SEP change has always been produced. No postoperative damage has been observed, however, as long as the CCT did not exceed 9 msec for 10 minutes (maximum normal CCT value is 6.7 msec) and as the cortical response had been visible throughout the whole surgical procedure. The critical value of CCT has been reached at a mean arterial pressure (MAP) lower than 60 Torr in patients with a normal preoperative SEP recording; at the opposite, in patients presenting with a prolonged preoperative CCT, the value of 9 msec was arrived at with a MAP value that is generally accepted as safe for all patients (75 Torr).(ABSTRACT TRUNCATED AT 250 WORDS)

  1. 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

  2. Time-frequency component analysis of somatosensory evoked potentials in rats

    PubMed Central

    Zhang, Zhi-Guo; Yang, Jun-Lin; Chan, Shing-Chow; Luk, Keith Dip-Kei; Hu, Yong

    2009-01-01

    Background Somatosensory evoked potential (SEP) signal usually contains a set of detailed temporal components measured and identified in a time domain, giving meaningful information on physiological mechanisms of the nervous system. The purpose of this study is to measure and identify detailed time-frequency components in normal SEP using time-frequency analysis (TFA) methods and to obtain their distribution pattern in the time-frequency domain. Methods This paper proposes to apply a high-resolution time-frequency analysis algorithm, the matching pursuit (MP), to extract detailed time-frequency components of SEP signals. The MP algorithm decomposes a SEP signal into a number of elementary time-frequency components and provides a time-frequency parameter description of the components. A clustering by estimation of the probability density function in parameter space is followed to identify stable SEP time-frequency components. Results Experimental results on cortical SEP signals of 28 mature rats show that a series of stable SEP time-frequency components can be identified using the MP decomposition algorithm. Based on the statistical properties of the component parameters, an approximated distribution of these components in time-frequency domain is suggested to describe the complex SEP response. Conclusion This study shows that there is a set of stable and minute time-frequency components in SEP signals, which are revealed by the MP decomposition and clustering. These stable SEP components have specific localizations in the time-frequency domain. PMID:19203394

  3. Simultaneous 3-T fMRI and high-density recording of human auditory evoked potentials.

    PubMed

    Scarff, Carrie J; Reynolds, Angela; Goodyear, Bradley G; Ponton, Curtis W; Dort, Joseph C; Eggermont, Jos J

    2004-11-01

    We acquired simultaneous high-field (3 T) functional magnetic resonance imaging (fMRI) and high-density (64- and 128-channel) EEG using a sparse sampling technique to measure auditory cortical activity generated by right ear stimulus presentation. Using dipole source localization, we showed that the anatomical location of the grand mean equivalent dipole of auditory evoked potentials (AEPs) and the center of gravity of fMRI activity were in good agreement in the horizontal plane. However, the grand mean equivalent dipole was located significantly superior in the cortex compared to fMRI activity. Interhemispheric asymmetry was exhibited by fMRI, whereas neither the AEP dipole moments nor the mean global field power (MGFP) of the AEPs showed significant asymmetry. Increasing the number of recording electrodes from 64 to 128 improved the accuracy of the equivalent dipole source localization but decreased the signal-to-noise ratio (SNR) of MR images. This suggests that 64 electrodes may be optimal for use in simultaneous recording of EEG and fMRI.

  4. [Somatosensory evoked potentials during natural and learned patterns of postural adjustment, accompanying limb movements in dogs].

    PubMed

    Gavrilenko, T; Frolov, A G; Ioffe, M E; Ganchev, G N; Aleksandrov, A V; Pavlova, O G

    2001-01-01

    A goal of the study was to investigate cortical reorganization corresponding to inhibition of innate motor patterns during motor learning. Functional changes in the sensorimotor cortex during learned rearrangement of the natural diagonal pattern of postural adjustment (PA) accompanying a hindlimb movement into a new one, the so-called unilateral pattern, were studied in dogs by testing somatosensory evoked potentials (SEP) in response to stimulation of a forelimb during PA immediately before the limb movement onset. During PA the latency and the amplitude of several SEP components decreased. In general, changes in SEP were less pronounced in the learned unilateral pattern of postural adjustment in comparison with the innate diagonal pattern, but the difference was significant only for some SEP components. The SEP late positivity in the learned postural pattern was replaced by a negativity. The SEP changes were similar independently of whether the test stimulus was applied on the forelimb loaded or unloaded during postural adjustment. The data suggest that changes in interrelations between different neuronal populations in the sensorimotor cortex during formation and realization of a learned motor program can be reflected in SEP changes.

  5. 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

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

    PubMed Central

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

    2014-01-01

    OBJECTIVES: This study investigated whether neurophysiologic responses (auditory evoked potentials) differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy. METHODS: The participants included 24 typically developing children (Control Group, mean age: eight years and ten months) and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months). Additionally, 12 study group children were enrolled in speech therapy (Study Group 1), and 11 were not enrolled in speech therapy (Study Group 2). The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups. RESULTS: Latency differences were observed between the groups (the control and study groups) regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy. CONCLUSION: The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy. PMID:24626949

  7. 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

  8. 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

  9. Short latency vestibular potentials evoked by electrical round window stimulation in the guinea pig.

    PubMed

    Bordure, P; Desmadryl, G; Uziel, A; Sans, A

    1989-11-01

    Short-latency potentials evoked by round window electrical stimulation were recorded in guinea pig by means of vertex-pinna skin electrodes using averaging techniques. Constant current shocks of 20 microseconds or 50 microseconds (25-300 microA) were used to evoke both auditory and vestibular brain-stem potentials. Pure auditory potentials, comparable to those evoked by acoustic clicks, were obtained by 20 microseconds electrical stimuli and disappeared during an auditory masking procedure made with a continuous white noise (110 dB SPL). Short latency potentials labeled V1, V2 and V3 were obtained by 50 microseconds electrical stimuli during an auditory masking procedure. This response disappeared after specific vestibular neurectomy, whereas the auditory response evoked by acoustic clicks or by electrical stimulation remained unchanged, suggesting that these latter potentials had a vestibular origin.

  10. Short latency vestibular potentials evoked by electrical round window stimulation in the guinea pig.

    PubMed

    Bordure, P; Desmadryl, G; Uziel, A; Sans, A

    1989-11-01

    Short-latency potentials evoked by round window electrical stimulation were recorded in guinea pig by means of vertex-pinna skin electrodes using averaging techniques. Constant current shocks of 20 microseconds or 50 microseconds (25-300 microA) were used to evoke both auditory and vestibular brain-stem potentials. Pure auditory potentials, comparable to those evoked by acoustic clicks, were obtained by 20 microseconds electrical stimuli and disappeared during an auditory masking procedure made with a continuous white noise (110 dB SPL). Short latency potentials labeled V1, V2 and V3 were obtained by 50 microseconds electrical stimuli during an auditory masking procedure. This response disappeared after specific vestibular neurectomy, whereas the auditory response evoked by acoustic clicks or by electrical stimulation remained unchanged, suggesting that these latter potentials had a vestibular origin. PMID:2479525

  11. Known and unexpected constraints evoke different kinematic, muscle, and motor cortical neuron responses during locomotion

    PubMed Central

    Stout, Erik E.; Sirota, Mikhail G.; Beloozerova, Irina N.

    2015-01-01

    During navigation through complex natural environments, people and animals must adapt their movements when the environment changes. The neural mechanisms of such adaptations are poorly understood, especially in respect to constraints that are unexpected and must be adapted to quickly. In this study, we recorded forelimb-related kinematics, muscle activity, and the activity of motor cortical neurons in cats walking along a raised horizontal ladder, a complex locomotion task requiring accurate limb placement. One of the crosspieces was motorized, and displaced before the cat stepped on the ladder or at different points along the cat’s progression over the ladder, either toward or away from the cat. We found that when the crosspiece was displaced before the cat stepped onto the ladder, kinematic modifications were complex and involved alterations of dynamics of all forelimb joints. When the crosspiece displaced unexpectedly while the cat was on the ladder, kinematic modifications were minimalistic and primarily involved distal joints. The activity of M. triceps and M. extensor digitorum communis differed based on the direction of displacement. Out of 151 neurons tested, 69% responded to at least one condition; however, neurons were significantly more likely to respond when crosspiece displacement was unexpected. Most often they responded during the swing phase. These results suggest that different neural mechanisms and motor control strategies are used to overcome constraints for locomotor movements depending on whether they are known or unexpectedly emerge. PMID:26302230

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

    PubMed

    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.

  13. Cerebral chemosensory evoked potentials elicited by chemical stimulation of the human olfactory and respiratory nasal mucosa.

    PubMed

    Kobal, G; Hummel, C

    1988-01-01

    A stimulation method was employed by which chemosensory evoked potentials were recorded without tactile somatosensory contamination. The purpose of the study was to determine whether potential components evoked by stimulation of the chemoreceptors of the trigeminal nerve can be distinguished from those of the olfactory nerve. The stimulants (vanillin, phenylethyl alcohol, limonene, menthol, anethol, benzaldehyde, carbon dioxide and a mixture of vanillin and carbon dioxide) were presented in a randomized order to 13 volunteers. Chemosensory evoked potentials to substances which anosmics are unable to perceive (vanillin, phenylethyl alcohol) were termed olfactory evoked potentials; potentials to CO2, which effected no olfactory sensations were termed chemo-somatosensory potentials. Analysis of variance revealed that the different substances resulted in statistically significant changes in the amplitudes and latencies of the evoked potentials, and also in the subjective estimates of intensity. An increased excitation of the somatosensory system resulted in reduced latencies and enhanced amplitudes of the evoked potentials. Responses to the mixture of carbon dioxide and vanillin appeared significantly earlier (50-150 msec) than responses to either substance alone.

  14. NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release.

    PubMed

    Hu, Zhitao; Vashlishan-Murray, Amy B; Kaplan, Joshua M

    2015-01-21

    A neuropeptide (NLP-12) and its receptor (CKR-2) potentiate tonic and evoked ACh release at Caenorhabditis elegans neuromuscular junctions. Increased evoked release is mediated by a presynaptic pathway (egl-30 Gαq and egl-8 PLCβ) that produces DAG, and by DAG binding to short and long UNC-13 proteins. Potentiation of tonic ACh release persists in mutants deficient for egl-30 Gαq and egl-8 PLCβ and requires DAG binding to UNC-13L (but not UNC-13S). Thus, NLP-12 adjusts tonic and evoked release by distinct mechanisms.

  15. Relationships between Electrically Evoked Potentials and Loudness Growth in Bilateral Cochlear Implant Users

    PubMed Central

    Kirby, Benjamin; Brown, Carolyn; Abbas, Paul; Etler, Christine; O’Brien, Sara

    2011-01-01

    SHORT SUMMARY Bilateral cochlear implantation has motivated efforts to ensure that sounds presented at equal levels to each ear are perceived as equally loud. Psychophysical loudness balancing is not always practical, especially with pediatric users. Electrophysiological potentials -- electrically evoked auditory brain stem response (EABR) and electrically evoked compound action potential (ECAP) measures -- may provide a means of approximating loudness balance. It was hypothesized that stimuli evoking equal amplitude neural responses would be more closely matched in loudness than stimuli with equal current levels. No significant differences in loudness discrepancy across ears were found for ECAP, EABR or matched current levels. PMID:22246138

  16. From cognitive networks to seizures: stimulus evoked dynamics in a coupled cortical network.

    PubMed

    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

  17. 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

  18. Comparing principal components analyses of evoked potentials recorded from heterogeneous groups of subjects.

    PubMed

    Roemer, R A; Josiassen, R C; Shagass, C

    1990-01-01

    Principal components analysis of evoked potentials differing between groups presents an interpretive problem, particularly in psychiatric research. Two sets of principal components and associated factor scores may appear to differ. The issue is to determine the extent to which visually differing principal components and resultant factor scores span the same factor space. Sets of evoked potentials from controls and from schizophrenics were each subjected to principal components analysis, from which factor score coefficients were computed for all subjects. This allowed determination of the extent to which (1) the two sets of basis waves were similar and (2) the factor scores resulting from the set of basis waves derived from principal components analysis of the control subjects' evoked potential data adequately represented those of the schizophrenics and vice-versa. Canonical correlation analyses indicated substantial similarities between the principal component structures (sets of basis waves). Multiple correlational analyses confirmed that the basis waves from either group spanned the other group's factor space. Factor scores from either set of basis waves were highly correlated. These results suggest that principal component structures derived from evoked potentials of a control group may be used in computing evoked potential factor scores of psychiatrically diverse populations even though the average evoked potentials of the groups may differ in several ways.

  19. The blink reflex and the corneal reflex are followed by cortical activity resembling the nociceptive potentials induced by trigeminal laser stimulation in man.

    PubMed

    de Tommaso, M; Libro, G; Guido, M; Sciruicchio, V; Puca, F

    2001-09-01

    Laser stimulation of the supraorbital regions evokes brain potentials (LEPs) related to trigeminal nociception. The aim of this study was to record the R2 component of the blink reflex and the corneal reflex in 20 normal subjects, comparing the scalp activity following these reflexes with the nociceptive potentials evoked by CO2 laser stimulation of supraorbital regions. Cortical and muscular reflexes evoked by stimulation of the first trigeminal branch were recorded simultaneously. The R2 component of the blink reflex and the corneal reflex were followed by two cortical peaks, which resembled morphologically N-P waves of LEPs. The two peaks demonstrated a difference in latency of approximately 40 ms, which is consistent with activation time of nociception. This finding suggests that these reflexes are induced by activation of small pain-related fibers. PMID:11524152

  20. The blink reflex and the corneal reflex are followed by cortical activity resembling the nociceptive potentials induced by trigeminal laser stimulation in man.

    PubMed

    de Tommaso, M; Libro, G; Guido, M; Sciruicchio, V; Puca, F

    2001-09-01

    Laser stimulation of the supraorbital regions evokes brain potentials (LEPs) related to trigeminal nociception. The aim of this study was to record the R2 component of the blink reflex and the corneal reflex in 20 normal subjects, comparing the scalp activity following these reflexes with the nociceptive potentials evoked by CO2 laser stimulation of supraorbital regions. Cortical and muscular reflexes evoked by stimulation of the first trigeminal branch were recorded simultaneously. The R2 component of the blink reflex and the corneal reflex were followed by two cortical peaks, which resembled morphologically N-P waves of LEPs. The two peaks demonstrated a difference in latency of approximately 40 ms, which is consistent with activation time of nociception. This finding suggests that these reflexes are induced by activation of small pain-related fibers.

  1. 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…

  2. Nociception-related somatosensory evoked potentials in awake dogs recorded after intra epidermal electrical stimulation.

    PubMed

    van Oostrom, Hugo; Stienen, Peter J; Doornenbal, Arie; Hellebrekers, Ludo J

    2009-02-01

    At present, the specific neurophysiologic methodology of recording pain-related evoked potentials is considered a most promising approach to objectively quantify pain in man. This study was designed to characterise and evaluate the use of somatosensory evoked potentials to study nociception in a canine model. To this aim, somatosensory evoked potentials were evoked by intra-epidermal electrical stimulation and recorded from the scalp in 8 beagle dogs. Characteristics determined were: (1) the conduction velocities of the peripheral nerve fibres involved, (2) the stimulus intensity response characteristics and (3) the evaluation of possible disturbance of the signals by muscular activity from the hind paw withdrawal reflex (EMG artefact). The results showed (1) the conduction velocities to be in the A-delta fibre range (i.e. fibres involved in nociception), (2) an increase in amplitude and a decrease in latency of the evoked potential following increasing stimulus intensities and (3) the absence of EMG artefact in the signals. These data indicate that the evoked potentials recorded, are related to nociception and thus are suited to quantitatively characterise the perception of noxious stimuli making this model useful for pain- and analgesia-related research.

  3. Reduced habituation to experimental pain in migraine patients: a CO(2) laser evoked potential study.

    PubMed

    Valeriani, M; de Tommaso, M; Restuccia, D; Le Pera, D; Guido, M; Iannetti, G D; Libro, G; Truini, A; Di Trapani, G; Puca, F; Tonali, P; Cruccu, G

    2003-09-01

    The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO(2) laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in 24 patients with migraine without aura (MO), 19 patients with chronic tension-type headache (CTTH), and 28 control subjects (CS). The habituation was studied by measuring the changes of LEP amplitudes across three consecutive repetitions of 30 trials each (the repetitions lasted 5 min and were separated by 5-min intervals). The slope of the regression line between LEP amplitude and number of repetitions was taken as an index of habituation. The LEPs consisted of middle-latency, low-amplitude responses (N1, contralateral temporal region, and P1, frontal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). The latency and amplitude of these responses were similar in both patients and controls. While CS and CTTH patients showed a significant habituation of the N2/P2 response, in MO patients this LEP component did not develop any habituation at all after face stimulation and showed a significantly lower habituation than in CS after hand stimulation. The habituation index of the vertex N2/P2 complex exceeded the normal limits in 13 out of the 24 MO patients and in none of the 19 CTTH patients (P<0.0001; Fisher's exact test). Moreover, while the N1-P1 amplitude showed a significant habituation in CS after hand stimulation, it did not change across repetitions in MO patients. In conclusion, no functional impairment of the nociceptive pathways, including the trigeminal pathways, was found in either MO or CTTH patients. But patients with migraine had a reduced habituation, which probably reflects an abnormal excitability of the cortical areas involved in

  4. Reduced habituation to experimental pain in migraine patients: a CO(2) laser evoked potential study.

    PubMed

    Valeriani, M; de Tommaso, M; Restuccia, D; Le Pera, D; Guido, M; Iannetti, G D; Libro, G; Truini, A; Di Trapani, G; Puca, F; Tonali, P; Cruccu, G

    2003-09-01

    The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO(2) laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in 24 patients with migraine without aura (MO), 19 patients with chronic tension-type headache (CTTH), and 28 control subjects (CS). The habituation was studied by measuring the changes of LEP amplitudes across three consecutive repetitions of 30 trials each (the repetitions lasted 5 min and were separated by 5-min intervals). The slope of the regression line between LEP amplitude and number of repetitions was taken as an index of habituation. The LEPs consisted of middle-latency, low-amplitude responses (N1, contralateral temporal region, and P1, frontal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). The latency and amplitude of these responses were similar in both patients and controls. While CS and CTTH patients showed a significant habituation of the N2/P2 response, in MO patients this LEP component did not develop any habituation at all after face stimulation and showed a significantly lower habituation than in CS after hand stimulation. The habituation index of the vertex N2/P2 complex exceeded the normal limits in 13 out of the 24 MO patients and in none of the 19 CTTH patients (P<0.0001; Fisher's exact test). Moreover, while the N1-P1 amplitude showed a significant habituation in CS after hand stimulation, it did not change across repetitions in MO patients. In conclusion, no functional impairment of the nociceptive pathways, including the trigeminal pathways, was found in either MO or CTTH patients. But patients with migraine had a reduced habituation, which probably reflects an abnormal excitability of the cortical areas involved in

  5. 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

  6. 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.

  7. Electrophysiologic studies of cervical vagus nerve stimulation in humans: II. Evoked potentials.

    PubMed

    Hammond, E J; Uthman, B M; Reid, S A; Wilder, B J

    1992-01-01

    Evidence from studies of experimental animals indicates that electrical stimulation of the vagus nerve not only can alter the EEG but evokes activity in specific brain areas. We report effects of electrical stimulation of the vagus nerve in 9 patients with medically intractable seizures as part of a clinical trial of chronic vagal stimulation for control of epilepsy. The left vagus nerve in the neck was stimulated with a programmable implanted stimulator. Effects of stimulus amplitude, duration, and rate were studied. Noncephalic reference recording of the vagus nerve evoked potential showed some unusual properties: a scalp negative component occurred with a latency of 12 ms, very high amplitude (< or = 60 microV), and widespread scalp distribution. Field distribution studies indicated that this potential was myogenic in origin and generated in the region of the stimulating electrodes in the neck area. Chemically induced muscle paralysis confirmed this observation. Bipolar scalp recording showed several small-amplitude topographically distinct potentials occurring in 30 ms. No effect, either acute or chronic, could be detected on pattern-reversal evoked potentials, auditory brainstem evoked potentials, auditory 40-Hz potentials, or cognitive evoked potentials. PMID:1464258

  8. [The action of ionizing radiation on the central nervous system (based on clinical and polymodal evoked potential data)].

    PubMed

    Shkol'nik, V M; Pogorelov, A V

    1998-05-01

    A clinical examination was done as was an investigation into polymodal evoked potentials (EP) of the brain in the group of 123 liquidators of the accident (LA) to the N 4 reactor unit of the Chernobyl nuclear power station. There was a steady decrease in the amplitude of auditory EP of the brain stem (AEPBS), somatosensory EP, visual EP and a great lengthening of latent periods (LP) of late cortical components H200, II300, H400. LP AEPBS appeared to be intact in 91.5% LA. Correlation was established between the hemodynamic and neurodynamic disorders suggesting to us that further postradiation nosology is brought about by morbid neuronal pattern, the formation of which is determined not only by radiation exposure but acquires the character of a multivariate process. PMID:9695553

  9. 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

  10. 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

  11. Differences in early sensory-perceptual processing in synesthesia: a visual evoked potential study.

    PubMed

    Barnett, Kylie J; Foxe, John J; Molholm, Sophie; Kelly, Simon P; Shalgi, Shani; Mitchell, Kevin J; Newell, Fiona N

    2008-11-15

    Synesthesia is a condition where stimulation of a single sensory modality or processing stream elicits an idiosyncratic, yet reliable perception in one or more other modalities or streams. Various models have been proposed to explain synesthesia, which have in common aberrant cross-activation of one cortical area by another. This has been observed directly in cases of linguistic-color synesthesia as cross-activation of the 'color area', V4, by stimulation of the grapheme area. The underlying neural substrates that mediate cross-activations in synesthesia are not well understood, however. In addition, the overall integrity of the visual system has never been assessed and it is not known whether wider differences in sensory-perceptual processing are associated with the condition. To assess whether fundamental differences in perceptual processing exist in synesthesia, we utilised high-density 128-channel electroencephalography (EEG) to measure sensory-perceptual processing using stimuli that differentially bias activation of the magnocellular and parvocellular pathways of the visual system. High and low spatial frequency gratings and luminance-contrast squares were presented to 15 synesthetes and 15 controls. We report, for the first time, early sensory-perceptual differences in synesthetes relative to non-synesthete controls in response to simple stimuli that do not elicit synesthetic color experiences. The differences are manifested in the early sensory components of the visual evoked potential (VEP) to stimuli that bias both magnocellular and parvocellular responses, but are opposite in direction, suggesting a differential effect on these two pathways. We discuss our results with reference to widespread connectivity differences as a broader phenotype of synesthesia.

  12. 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.

  13. 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

  14. [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.

  15. [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

  16. 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.

  17. Effect of body temperature on visual evoked potential delay and visual perception in multiple sclerosis.

    PubMed

    Regan, D; Murray, T J; Silver, R

    1977-11-01

    Seven multiple sclerosis patients were cooled and four heated, but evoked potential delay changed in only five out 11 experiments. Control limits were set by cooling eight and heating four control subjects. One patient gave anomalous results in that although heating degraded perceptual delay and visual acuity, and depressed the sine wave grating MTF, double-flash resolution was improved. An explanation is proposed in terms of the pattern of axonal demyelination. The medium frequency flicker evoked potential test seems to be a less reliable means of monitoring the progress of demyelination in multiple sclerosis patients than is double-flash campimetry or perceptual delay campimetry, although in some situations the objectivity of the evoked potential test would be advantageous.

  18. Quantifying the effect of isoflurane and nitrous oxide on somatosensory-evoked potentials.

    PubMed

    Devadoss, Usha; Babu, S; Cherian, Vt

    2010-01-01

    Anaesthetic techniques may have a significant effect on intraoperative-evoked potentials (EP). The present study is designed to compare Propofol anaesthesia with Isoflurane (with or without nitrous oxide) during intraoperative somatosensory-evoked potential (SSEP) monitoring in 15 ASA Grade I and II patients undergoing surgery for intracranial tumours. SSEPs in response to median and posterior tibial nerve stimulation were recorded under four different anaesthetic conditions: 1) Propofol infusion and ventilation with air-oxygen, 2) Isoflurane, 1.0 MAC and ventilation with air-oxygen, 3) Isoflurane 1.0 MAC and ventilation with nitrous oxide-oxygen, and 4) Return to Isoflurane, 1.0 MAC and ventilation with air-oxygen. Intraoperative monitoring of somatosensory evoked potentials is best recordable using Propofol. The morphology of the EP is reproducible with Isoflurane. This effect is exaggerated when it is advisable to avoid nitrous oxide. PMID:20532071

  19. Dynamic extraction of visual evoked potentials through spatial analysis and dipole localization.

    PubMed

    Wang, Y; Yang, F

    1995-08-01

    The dynamic extraction of evoked potential is a problem of great interest in EEG signal processing. In this paper, a comprehensive method is presented which integrates spatial analysis and dipole localization to make full use of the spatial-temporal information contained in the multichannel stimulation records. A realistic double boundary head model is constructed through CT scans and a two-step method devised to overcome the ill-posed nature of the forward problem of EEG caused by the low conductivity of the skull. As a result, visual evoked potentials can be effectively extracted from only two consecutive records and the dynamic information of visual evoked potential thus procured. The efficiency of the presented method has been verified by means of computer simulation and a clinical experiment.

  20. Attention Influences Single Unit and Local Field Potential Response Latencies in Visual Cortical Area V4

    PubMed Central

    Sundberg, Kristy A.; Mitchell, Jude F.; Gawne, Timothy J.

    2012-01-01

    Many previous studies have demonstrated that changes in selective attention can alter the response magnitude of visual cortical neurons, but there has been little evidence for attention affecting response latency. Small latency differences, though hard to detect, can potentially be of functional importance, and may also give insight into the mechanisms of neuronal computation. We therefore reexamined the effect of attention on the response latency of both single units and the local field potential (LFP) in primate visual cortical area V4. We find that attention does produce small (1–2 ms) but significant reductions in the latency of both the spiking and LFP responses. Though attention, like contrast elevation, reduces response latencies, we find that the two have different effects on the magnitude of the LFP. Contrast elevations increase and attention decreases the magnitude of the initial deflection of the stimulus-evoked LFP. Both contrast elevation and attention increase the magnitude of the spiking response. We speculate that latencies may be reduced at higher contrast because stronger stimulus inputs drive neurons more rapidly to spiking threshold, while attention may reduce latencies by placing neurons in a more depolarized state closer to threshold before stimulus onset. PMID:23136440

  1. 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

  2. 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

  3. 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

  4. Transient brain activity explains the spectral content of steady-state visual evoked potentials.

    PubMed

    Gaume, Antoine; Vialatte, François; Dreyfus, Gérard

    2014-01-01

    Steady-state visual evoked potentials (SSVEPs) are widely used in the design of brain-computer interfaces (BCIs). A lot of effort has therefore been devoted to find a fast and reliable way to detect SSVEPs. We study the link between transient and steady-state VEPs and show that it is possible to predict the spectral content of a subject's SSVEPs by simulating trains of transient VEPs. This could lead to a better understanding of evoked potentials as well as to better performances of SSVEP-based BCIs, by providing a tool to improve SSVEP detection algorithms.

  5. 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

  6. Sleep Promotes Cortical Response Potentiation Following Visual Experience

    PubMed Central

    Aton, Sara J.; Suresh, Aneesha; Broussard, Christopher; Frank, Marcos G.

    2014-01-01

    Study Objectives: Sleep has been hypothesized to globally reduce synaptic strength. However, recent findings suggest that in the context of learning and memory consolidation, sleep may promote synaptic potentiation. We tested the requirement for sleep in a naturally occurring form of experience-dependent synaptic potentiation in the adult mouse visual cortex (V1), which is initiated by patterned visual experience. Design: Visual responses were recorded in individual V1 neurons before and after presentation of an oriented grating stimulus, and after subsequent sleep or sleep deprivation. Measurements and Results: We find that V1 response potentiation—associated with a shift in orientation preference in favor of the presented stimulus—occurs only after sleep and only during the entrained circadian sleep phase, and is blocked by sleep deprivation. Induction of plasticity following stimulus presentation is associated with an increase in principal neuron firing in V1, which is present in all behavioral states and occurs regardless of time of day. Sleep dependent potentiation is proportional to phase-locking of neuronal activity with thalamocortical spindle oscillations. Conclusions: Our results suggest that sleep can promote cortical synaptic potentiation in vivo, and that this potentiation may be mediated by slow wave sleep spindles. Citation: Aton SJ, Suresh A, Broussard C, Frank MG. Sleep promotes cortical response potentiation following visual experience. SLEEP 2014;37(7):1163-1170. PMID:25061244

  7. 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

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

    PubMed

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

    2015-10-01

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

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

    PubMed Central

    Huidobro, Nayeli; Silva, Mayte; Flores, Amira; Trenado, Carlos; Quintanar, Luis; Arias-Carrión, Oscar; Kristeva, Rumyana

    2015-01-01

    The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. PMID:26156387

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

    PubMed

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

    2015-10-01

    The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. PMID:26156387

  11. Vestibular evoked potentials with short and middle latencies recorded in humans.

    PubMed

    Leibner, E; Elidan, J; Freeman, S; Sela, M; Nitzan, M; Sohmer, H

    1990-01-01

    Following success in recording short latency vestibular evoked potentials in experimental animals, we have succeeded in our attempts to record such potentials in human subjects. The stimuli were repetitive, short steps of high intensity angular acceleration (10,000 degrees/sec2) with short rise times which would synchronously activate many neurons of the vestibular pathway. Stringent control procedures ensured that the recorded activity was not an artefact. Short latency vestibular evoked potentials were recorded in 10 normal subjects with peak latencies of 3.5, 6.0 and 8.4 msec and amplitudes of 0.5 microV. Middle latency potentials were also recorded with latencies of 8.8, 18.8 and 26.8 msec and amplitudes of 15 microV. These responses were absent in a cadaver and in patients with bilateral dead labyrinths. In normal subjects, these vestibular evoked potentials were not affected by white noise. In conclusion, short and middle latency vestibular evoked potentials were recorded in normal human subjects. PMID:2289418

  12. Histological correlates of N40 auditory evoked potentials in adult rats after neonatal ventral hippocampal lesion: animal model of schizophrenia.

    PubMed

    Romero-Pimentel, A L; Vázquez-Roque, R A; Camacho-Abrego, I; Hoffman, K L; Linares, P; Flores, G; Manjarrez, E

    2014-11-01

    The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.

  13. The effect of swallowing treatments on corticobulbar excitability: a review of transcranial magnetic stimulation induced motor evoked potentials.

    PubMed

    Macrae, Phoebe R; Jones, Richard D; Huckabee, Maggie-Lee

    2014-08-15

    Transcranial magnetic stimulation (TMS) has been used extensively as a method of investigating the corticomotor physiology of many motor tasks, including healthy and disordered swallowing. Changes in excitability of cortical projections to various swallowing muscles have been documented in response to treatments with TMS induced motor evoked potentials (MEPs). These studies have provided valuable insight into CNS response to swallowing impairment, and more importantly, the adaptations associated with functional recovery. However, unique obstacles are presented when investigating corticobulbar neurophysiology associated with the complex task of swallowing. Stringent methodological control and supplementary outcome measures are required to ensure robust and clinically applicable findings. This article offers a tutorial for the researcher who may be considering the use of TMS for investigating changes in cortical excitability associated with various swallowing paradigms. Included is a review of the mechanisms of TMS and what can be measured with this technique, a summary of existing research using MEPs to investigate swallowing, a review of methodological factors that may influence outcomes, and proposed directions for new areas of research.

  14. Effects of adenosine triphosphate (ATP) on somatosensory evoked potentials in humans anesthetized with isoflurane and nitrous oxide.

    PubMed

    Andoh, T; Ohtsuka, T; Okazaki, K; Okutsu, Y; Okumura, F

    1993-08-01

    In order to examine the usefulness of adenosine triphosphate (ATP) as an adjuvant to anesthesia for surgery requiring intraoperative somatosensory evoked potential (SSEP) monitoring, we have studied the effects of ATP on SSEPs in patients anesthetized with isoflurane and nitrous oxide (N2O). A control recording of SSEP was performed while anesthesia was maintained with 0.5% end-tidal concentration of isoflurane in 60% N2O. The recordings were repeated after an ATP infusion had been added to this basal anesthesia at the rates of 100 micrograms.kg bw-1.min-1 and 200 micrograms.kg bw-1.min-1. SSEP was also studied when end-tidal isoflurane concentration was increased to 1.5% after cessation of ATP infusion. An infusion of ATP combined with 0.5% isoflurane and 60% N2O effectively inhibited an increase in blood pressure during surgery. The amplitude of the cortical component of SSEP was lowered by 1.5% isoflurane, which also increased both cortical and spinal latencies as well as central conduction time (CCT). In contrast ATP infusions at both rates induced no significant changes in latencies, amplitude and CCT. The results indicate that ATP infusion combined with 0.5% isoflurane in 60% N2O can be a useful anesthetic technique for intraoperative SSEP monitoring because adequate anesthetic depth can be maintained by a low concentration of anesthetics without further suppression of SSEPs. PMID:8213025

  15. Colored focal visual evoked potentials by cathode ray tube versus scanning laser ophthalmoscope.

    PubMed

    Rigaudière, F; Le Gargasson, J F; Guez, J E; Grall, Y

    1993-01-01

    We compared the focal visual evoked potentials obtained in 52 young subjects with normal vision, evoked by means of three alternating black/color checkerboards generated by a trichromic cathode ray tube (dominant wavelength, 514 nm; colorimetric purity, 0.45) and by means of a scanning laser ophthalmoscope (argon laser beam, 514 nm; colorimetric purity, approximately 1). These three checkerboards, with an area of 3.5 degrees x 3.5 degrees (stimulating the fovea), then with an area of 3.5 degrees x 3.5 degrees with a central exclusion of 1.5 degrees x 1.5 degrees (stimulating the perifoveola) and finally with an area of 1.5 degrees x 1.5 degrees (stimulating the foveola) were presented within a field (8 degrees x 8 degrees) of homogeneous luminance of 170 cd/m2 and 1500 cd/m2, respectively. Their check sizes were 30', with a reversal temporal frequency of 0.75 Hz. The transient focal visual evoked potentials recorded with these three stimuli generated by the two types of stimulators were clearly detected for at least 85% of subjects. Their characteristics (waveform, amplitude and culmination times of the different waves) were comparable, regardless of the stimulator used (cathode ray tube or scanning laser ophthalmoscope). These results suggest that, under these various conditions of luminance and colorimetric purity, the neurophysiologic circuits tested function in identical ways. The focal visual evoked potential signs, now clearly defined by means of stimuli generated by cathode ray tubes, therefore apparently can be applied to the focal visual evoked potential evoked by stimuli generated by the scanning laser ophthalmoscope.

  16. 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

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

    PubMed

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

    2016-03-01

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

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

    PubMed

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

    2016-03-01

    Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI. PMID:26677784

  19. [Indications for studying evoked potentials in childhood. Methods--indications--value].

    PubMed

    Görke, W

    1986-01-01

    Evoked potentials (EP) represent a valuable addition to currently applied diagnostic methods in neuropediatrics. Profound knowledge of the neurophysiological conditions producing EP-alterations allows basic conclusions, that cannot be gained or replaced by other investigations. EP-investigation demonstrate the existence but not the nature of a lesion in the CNS. Further diagnostic work-up usually will be necessary. Proved EP-alterations produce reproducible diagnostic results and give clues regarding its localization. Evoked potentials can be used as a screening-method for neuropediatric diseases. By follow-up examinations it is possible to show, wether there is progression or not. Testing for evoked potentials is indicated in suspected cerebral palsy in infants, in all cases of psychomotor retardation of unknown origin, impairment of vision or hearing, in cases of brain trauma or in suspected brainstem process, lesions of N. opticus or visual projective systems, neurometabolic or degenerative CNS disease, phacomatosis, progressive myoclonic epilepsy, ceroidlipofuscinosis Jansky-Bielschowski, benign partial epilepsy with extreme somatosensory evoked potentials, Ramsey-Hunt-Syndrome and aplasia of the corpus callosum.

  20. 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…

  1. 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…

  2. 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…

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

    PubMed

    Ellingson, Roger M; Oken, Barry

    2010-01-01

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

  4. 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…

  5. 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

  6. Spinal pathways mediating somatosensory evoked potentials from cutaneous and muscle nerves in the cat.

    PubMed

    Ducati, A; Schieppati, M

    1980-01-01

    The Authors give evidence on the function of a pathway mediating somatosensory evoked potentials (SEPs) from muscle nerves, other than the dorsal columns: physiological and anatomical data prove its location to be in the spinothalamic tract. Previous contrasting results on the topic are discussed.

  7. Effects of prenatal exposure to carbamazepine on brainstem auditory evoked potentials in infants of epileptic mothers.

    PubMed

    Poblano, Adrián; Belmont, Aurora; Sosa, Jesús; Ibarra, Jorge; Rosas, Yolanda; López, Vivián; Garza, Saúl

    2002-05-01

    The purpose of this study was to determine if there are any correlations between carbamazepine serum levels of epileptic mothers during pregnancy and the brainstem auditory evoked potentials in their infants as an index of drug neurotoxicity in newborns exposed prenatally. We included 20 epileptic mothers with carbamazepine medication and their 20 otherwise healthy infants. The study was conducted from September 1, 1993, to December 15, 1999. Serum carbamazepine determinations were performed monthly by enzymatic immunoanalysis in the mothers, and the averages for each trimester during pregnancy were calculated. Brainstem auditory evoked potentials were performed at 10.2 +/- 4.6 weeks of postnatal life. Pearson's correlations were calculated between carbamazepine serum levels during pregnancy and waves and interwave intervals of brainstem auditory evoked potentials. Both examinations were performed without knowledge of the results of the other investigations. No alterations in the infants' brainstem auditory evoked potentials were evident, and carbamazepine determinations were within therapeutic levels. Significant Pearson's correlations between latencies of waves III and V and third trimester of carbamazepine serum concentration levels and I-V interwave intervals to third-trimester minimum serum levels of carbamazepine were found. The findings suggest that the higher carbamazepine levels in mothers are related to increased latencies in waves III and V and I-V interwave intervals in infants subclinically, which could be an early index of fetal neurotoxicity.

  8. 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

  9. An involvement of BDNF and PI3-K/Akt in the anti-apoptotic effect of memantine on staurosporine-evoked cell death in primary cortical neurons.

    PubMed

    Jantas, D; Szymanska, M; Budziszewska, B; Lason, W

    2009-07-01

    Memantine, a clinically used NMDA receptor antagonist possesses neuroprotective properties, but the exact mechanisms of its beneficial action on neuronal survival are poorly recognized. In the present study, some intracellular mechanisms of memantine effects on staurosporine-evoked cell death were investigated in primary cortical neurons. Memantine (0.1-2 muM) suppressed neuronal apoptosis evoked by staurosporine in 7 DIV cortical neurons, whereas other antagonists of NMDA receptor, MK-801 (1 muM) and AP-5 (100 muM) were ineffective. The anti-apoptotic effects of memantine were not connected with any changes in cytoplasmic calcium concentration or reactive oxygen species level. The immunoblot analysis showed that the staurosporine induced a decrease in p-Akt protein kinase level and that this effect was reversed by memantine treatment. Moreover, the PI3-K inhibitors, wortmannin and LY 294002 attenuated the anti-apoptotic action of memantine on staurosporine-induced cell damage. Furthermore, the ELISA studies showed increased cellular and released BDNF protein level after combined treatment with memantine and staurosporine. There was no effect of memantine on the activation and expression of other protein kinases involved in the mechanism of cellular survival, i.e. ERK1/2, JNK and GSK3-beta. The obtained data suggest an NMDAR-independent action of memantine in attenuation of neuronal apoptosis and point to the engagement of BDNF and PI3-K/Akt pathway in these processes.

  10. Self-modeling structure of evoked postsynaptic potentials.

    PubMed

    Viele, Kert; Lancaster, Mark; Cooper, Robin L

    2006-07-01

    With the simplicity of the synaptic structure and physiology at neuromuscular junctions (NMJs) of crayfish and the given transmitter being released in quantal packets, a detailed assessment in the fundamental processes of chemical synaptic transmission is possible. Since the quantal event is the basic element of transmission, we consider an approach to further understand the characteristics of quantal responses. In this study, we introduce a method for combining information across excitatory postsynaptic potentials (EPSPs) that are quantal in nature. The method is called self-modeling regression, known in the statistics literature as SEMOR. This method illustrates that the differing timing and heights of EPSPs can be described with four coefficients measuring affine (shift and scale) transformations of the x and y axes. We demonstrate that this relationship allows us to provide a unified schema for the many functionals currently used in the literature, such as peak amplitude, tau, latency, area under the curve, or decay time. Computer code in R is available on the internet to perform the analysis.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  16. Running Reduces Uncontrollable Stress-Evoked Serotonin and Potentiates Stress-Evoked Dopamine Concentrations in the Rat Dorsal Striatum.

    PubMed

    Clark, Peter J; Amat, Jose; McConnell, Sara O; Ghasem, Parsa R; Greenwood, Benjamin N; Maier, Steven F; Fleshner, Monika

    2015-01-01

    Accumulating evidence from both the human and animal literature indicates that exercise reduces the negative consequences of stress. The neurobiological etiology for this stress protection, however, is not completely understood. Our lab reported that voluntary wheel running protects rats from expressing depression-like instrumental learning deficits on the shuttle box escape task after exposure to unpredictable and inescapable tail shocks (uncontrollable stress). Impaired escape behavior is a result of stress-sensitized serotonin (5-HT) neuron activity in the dorsal raphe (DRN) and subsequent excessive release of 5-HT into the dorsal striatum following exposure to a comparatively mild stressor. However, the possible mechanisms by which exercise prevents stress-induced escape deficits are not well characterized. The purpose of this experiment was to test the hypothesis that exercise blunts the stress-evoked release of 5-HT in the dorsal striatum. Changes to dopamine (DA) levels were also examined, since striatal DA signaling is critical for instrumental learning and can be influenced by changes to 5-HT activity. Adult male F344 rats, housed with or without running wheels for 6 weeks, were either exposed to tail shock or remained undisturbed in laboratory cages. Twenty-four hours later, microdialysis was performed in the medial (DMS) and lateral (DLS) dorsal striatum to collect extracellular 5-HT and DA before, during, and following 2 mild foot shocks. We report wheel running prevents foot shock-induced elevation of extracellular 5-HT and potentiates DA concentrations in both the DMS and DLS approximately 24 h following exposure to uncontrollable stress. These data may provide a possible mechanism by which exercise prevents depression-like instrumental learning deficits following exposure to acute stress. PMID:26555633

  17. Running Reduces Uncontrollable Stress-Evoked Serotonin and Potentiates Stress-Evoked Dopamine Concentrations in the Rat Dorsal Striatum

    PubMed Central

    Clark, Peter J.; Amat, Jose; McConnell, Sara O.; Ghasem, Parsa R.; Greenwood, Benjamin N.; Maier, Steven F.; Fleshner, Monika

    2015-01-01

    Accumulating evidence from both the human and animal literature indicates that exercise reduces the negative consequences of stress. The neurobiological etiology for this stress protection, however, is not completely understood. Our lab reported that voluntary wheel running protects rats from expressing depression-like instrumental learning deficits on the shuttle box escape task after exposure to unpredictable and inescapable tail shocks (uncontrollable stress). Impaired escape behavior is a result of stress-sensitized serotonin (5-HT) neuron activity in the dorsal raphe (DRN) and subsequent excessive release of 5-HT into the dorsal striatum following exposure to a comparatively mild stressor. However, the possible mechanisms by which exercise prevents stress-induced escape deficits are not well characterized. The purpose of this experiment was to test the hypothesis that exercise blunts the stress-evoked release of 5-HT in the dorsal striatum. Changes to dopamine (DA) levels were also examined, since striatal DA signaling is critical for instrumental learning and can be influenced by changes to 5-HT activity. Adult male F344 rats, housed with or without running wheels for 6 weeks, were either exposed to tail shock or remained undisturbed in laboratory cages. Twenty-four hours later, microdialysis was performed in the medial (DMS) and lateral (DLS) dorsal striatum to collect extracellular 5-HT and DA before, during, and following 2 mild foot shocks. We report wheel running prevents foot shock-induced elevation of extracellular 5-HT and potentiates DA concentrations in both the DMS and DLS approximately 24 h following exposure to uncontrollable stress. These data may provide a possible mechanism by which exercise prevents depression-like instrumental learning deficits following exposure to acute stress. PMID:26555633

  18. A Novel Method of Brainstem Auditory Evoked Potentials Using Complex Verbal Stimuli

    PubMed Central

    Kouni, Sophia N; Koutsojannis, Constantinos; Ziavra, Nausika; Giannopoulos, Sotirios

    2014-01-01

    Background: The click and tone-evoked auditory brainstem responses are widely used in clinical practice due to their consistency and predictability. More recently, the speech-evoked responses have been used to evaluate subcortical processing of complex signals, not revealed by responses to clicks and tones. Aims: Disyllable stimuli corresponding to familiar words can induce a pattern of voltage fluctuations in the brain stem resulting in a familiar waveform, and they can yield better information about brain stem nuclei along the ascending central auditory pathway. Materials and Methods: We describe a new method with the use of the disyllable word “baba” corresponding to English “daddy” that is commonly used in many other ethnic languages spanning from West Africa to the Eastern Mediterranean all the way to the East Asia. Results: This method was applied in 20 young adults institutionally diagnosed as dyslexic (10 subjects) or light dyslexic (10 subjects) who were matched with 20 sex, age, education, hearing sensitivity, and IQ-matched normal subjects. The absolute peak latencies of the negative wave C and the interpeak latencies of A-C elicited by verbal stimuli “baba” were found to be significantly increased in the dyslexic group in comparison with the control group. Conclusions: The method is easy and helpful to diagnose abnormalities affecting the auditory pathway, to identify subjects with early perception and cortical representation abnormalities, and to apply the suitable therapeutic and rehabilitation management. PMID:25210677

  19. 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

  20. Recording of auditory middle latency evoked potentials during the practice of meditation with the syllable 'OM'.

    PubMed

    Telles, S; Desiraju, T

    1993-10-01

    Middle latency auditory evoked potentials were examined in 7 proficient subjects during the practice of meditation on the syllable 'OM', to determine whether these potentials would differ significantly from those recorded during the baseline state without practicing mediation. Similar records were also obtained in 7 'naive' subjects, matched for age, before and during a control period which involved sitting with eyes closed, and with no special instructions for focusing their thoughts. There was considerable inter-subject variability in the different components. However, during meditation there was a small but significant reduction in the peak latency of the Nb wave (the maximum negativity occurring between 35 and 65 msec). This reduction was observed consistently during the 3 repeat sessions of each subject, while the 'naive' subjects did not show this change. These results suggest that the inter-subject variability of middle latency auditory evoked potentials precludes using them as the method of choice for assessing the effects of meditation. The small but consistent decrease in the Nb wave peak latency, indicates that the middle latency auditory evoked potentials do change with meditation. However, the variability of the potentials may mask subtle changes.

  1. 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.

  2. Spontaneous EEG spikes in the normal hippocampus. III. Relations to evoked potentials.

    PubMed

    Suzuki, S S; Smith, G K

    1988-06-01

    Spontaneous EEG spikes (SPKs) were recorded from the CA1 region of the dorsal hippocampus in normal rats during behavioral states not accompanied by rhythmical slow activity (RSA). SPKs were positive in stratum oriens, negative in stratum radiatum and accompanied by population bursts (PBs) in stratum pyramidale. In order to examine the origin of SPKs and PBs single pulse or brief high frequency electrical stimuli were applied to the Schaffer collateral/commissural pathway. Evoked potentials were recorded and compared with spontaneous SPKs and PBs. The results indicate the following: (1) the laminar amplitude profile of spontaneous SPKs was similar to that of population EPSPs evoked by stimulation of the Schaffer collateral/commissural pathway; (2) the population EPSP most similar to the spontaneous SPK was evoked by a brief (20-60 msec) train of high frequency (125-500 Hz) pulses; (3) the same pattern of stimulation was also found to be most efficient in evoking a series of multiple population spikes resembling a type of spontaneous PB (ripple). These observations suggest that SPKs and PBs in CA1 represent population EPSPs and multiple population spikes, respectively and that these CA1 events are triggered by brief, high frequency burst discharges of CA3 pyramidal cells via the Schaffer collateral and commissural pathway. PMID:2453331

  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. Conditioned cortical slow potential responses in urethane anesthetized rats.

    PubMed

    Pirch, J H; Corbus, M J; Ebenezer, I

    1985-01-01

    Cortical slow potential (SP) responses to tone or light stimuli preceding medial forebrain bundle (MFB) stimulation were recorded in urethane anesthetized rats. In the first study, rats were implanted with Ag-AgCl electrodes for recording frontal cortex SPs as well as monopolar electrodes for MFB stimulation. Following recovery, optimum stimulation parameters for SP conditioning were determined for each rat during self-stimulation sessions. These animals were then subjected to extensive associative conditioning in the unanesthetized state. Trials were presented at variable intervals and a 2-sec tone preceded a single 0.5 sec train of MFB stimulation. Negative SP responses developed with training and responses of similar waveform and amplitude were observed in the same animals under urethane anesthesia. Other rats were implanted with MFB stimulating electrodes and, after recovery, stimulation parameters were determined as above but the animals were not subjected to the conditioning procedure prior to urethane administration. Under urethane anesthesia, Ag-AgCl electrodes were placed on the dura over frontal cortex for recording SP responses during pseudoconditioning, conditioning, extinction and retraining trials, using either light or tone stimuli. Negative bilateral SP responses to the tone or light were minimal or nonexistent during pseudoconditioning, developed gradually with pairing, diminished markedly during extinction and returned to maximum amplitude with retraining. The SP responses also reflected discrimination between reinforced and nonreinforced tone and light stimuli as well as reversal conditioning. Furthermore, turning off a light could also serve as the conditioned stimulus for SP response generation. Cortical slow potential responses can be conditioned in urethane anesthetized rats. Therefore, it may be possible to apply additional neurophysiological techniques in these animals to investigate event-related slow potential mechanisms. PMID:3872286

  6. Suggestion and pain in migraine: a study by laser evoked potentials.

    PubMed

    de Tommaso, Marina; Federici, Antonio; Franco, Giovanni; Ricci, Katia; Lorenzo, Marta; Delussi, Marianna; Vecchio, Eleonora; Serpino, Claudia; Livrea, Paolo; Todarello, Orlando

    2012-03-01

    Belief and expectation are part of placebo effect. Migraine patients are characterized by a dysfunctional modulation of pain processing, though a clear placebo effect emerges in clinical trials. The aim of the study was to evaluate the effect of visual and verbal suggestion on subjective pain sensation and cortical responses evoked by CO2 painful laser stimuli in migraine without aura patients vs healthy controls. Twenty-six patients were recorded during the inter-ictal phase and compared to 26 sex and age-matched controls. The right hand and the right supraorbital zone were stimulated during a not conditioned and a conditioned task, where laser stimuli were delivered after a verbal and visual cues of decreased (D), increased (I) or basal (B) intensity, which was left unmodified during the entire task. In control subjects pain rating changed, according to the announced intensity, while in migraine patients the basal hyper-algesia remained unmodified. The N1 and N2 amplitudes tended to change coherently with the stimulus cue in controls, while an opposite paradoxical increase in decreasing condition emerged in migraine. The P2 amplitude modulation was also reduced in migraine, differently from controls. The altered pattern of pain rating and N2 amplitude modulation concurred with frequency of migraine, disability and allodynia. In controls suggestion influenced cortical pain processing and subjective pain rating, while in migraine a peculiar pattern of cortical activation contrasted external cues in order to maintain the basal hyper-algesia. This scarce influence of induced suggestion on pain experience seemed to characterize patients with more severe migraine and central sensitization.

  7. 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

  8. 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.

  9. [Anesthesia with flunitrazepam/fentanyl and isoflurane/fentanyl. Unconscious perception and mid-latency auditory evoked potentials].

    PubMed

    Schwender, D; Kaiser, A; Klasing, S; Faber-Züllig, E; Golling, W; Pöppel, E; Peter, K

    1994-05-01

    There is a high incidence of intraoperative awareness during cardiac surgery. Mid-latency auditory evoked potentials (MLAEP) reflect the primary cortical processing of auditory stimuli. In the present study, we investigated MLAEP and explicit and implicit memory for information presented during cardiac anaesthesia. PATIENTS AND METHODS. Institutional approval and informed consent was obtained in 30 patients scheduled for elective cardiac surgery. Anaesthesia was induced in group I (n = 10) with flunitrazepam/fentanyl (0.01 mg/kg) and maintained with flunitrazepam/fentanyl (1.2 mg/h). The patients in group II (n = 10) received etomidate (0.25 mg/kg) and fentanyl (0.005 mg/kg) for induction and isoflurane (0.6-1.2 vol%)/fentanyl (1.2 mg/h) for maintenance of general anaesthesia. Group III (n = 10) served as a control and patients were anaesthetized as in I or II. After sternotomy an audiotape that included an implicit memory task was presented to the patients in groups I and II. The story of Robinson Crusoe was told, and it was suggested to the patients that they remember Robinson Crusoe when asked what they associated with the word Friday 3-5 days postoperatively. Auditory evoked potentials were recorded awake and during general anaesthesia before and after the audiotape presentation on vertex (positive) and mastoids on both sides (negative). Auditory clicks were presented binaurally at 70 dBnHL at a rate of 9.3 Hz. Using the electrodiagnostic system Pathfinder I (Nicolet), 1000 successive stimulus responses were averaged over a 100 ms poststimulus interval and analyzed off-line. Latencies of the peak V, Na, Pa were measured. V belongs to the brainstem-generated potentials, which demonstrates that auditory stimuli were correctly transduced. Na, Pa are generated in the primary auditory cortex of the temporal lobe and are the electrophysiological correlate of the primary cortical processing of the auditory stimuli. RESULTS. None of the patients had an explicit memory

  10. 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

  11. The effects of halothane on somatosensory and flash visual evoked potentials during operations.

    PubMed

    Wang, A D; Costa e Silva, I; Symon, L; Jewkes, D

    1985-06-01

    Intraoperative use of somatosensory evoked potentials (SEP's) to monitor intracranial aneurysm surgery and flash visual evoked potentials (F-VEP's) for parasellar surgery have been routinely employed in our clinic. We found that both EP modalities are sensitive to the changing concentration of our standard hypotensive agent, halothane. The prolongation of the N14-N20 interpeak latency to median nerve stimulation at the wrist, and prolongation of P100 latency with altered configuration of early VEP components to flash light stimulation, appear to be the results of direct pharmacological effects of the agent and not an effect of secondary hypotension. VEP is found easily abolished by halothane at a concentration of 2.0%, while the SEP is more resistant. Halothane is not ideal however when monitoring intraoperative VEP.

  12. Visual evoked potentials in dementia: a meta-analysis and empirical study of Alzheimer's disease patients.

    PubMed

    Pollock, V E; Schneider, L S; Chui, H C; Henderson, V; Zemansky, M; Sloane, R B

    1989-04-15

    A meta-analytic review of flash and pattern reversal visual evoked potential research indicates that elderly demented patients have longer P100 latencies than age-matched control subjects. In the present empirical research, patients with research diagnoses of probable Alzheimer's disease were compared with sex- and age-matched control subjects using P100 latencies of visual evoked potentials (VEP) elicited by flash and pattern reversal. As compared to control subjects, Alzheimer's disease patients showed significantly longer P100 latencies of the VEP elicited by pattern reversal; the flash P100 only marginally distinguished them. These findings are discussed within the context of VEP recording practices, patient selection, sex and age matching of control subjects, and the visual system.

  13. 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

  14. Enabling fast brain-computer interaction by single-trial extraction of visual evoked potentials.

    PubMed

    Chen, Min; Guan, Jinan; Liu, Haihua

    2011-10-01

    This paper investigates the challenging issue of enabling fast brain-computer interaction to construct a mental speller. Exploiting visual evoked potentials as communication carriers, an online paradigm called "imitating-human-natural-reading" is realized. In this online paradigm, single-trial estimation with the intrinsically real-time feature should be used instead of grand average that is traditionally used in the cognitive or clinical experiments. By the use of several montages of component features from four channels with parameter optimization, we explored the support vector machines-based single-trial estimation of evoked potentials. The results on a human-subject show the advantages of the inducing paradigm used in our mental speller with a high classification rate.

  15. 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

  16. 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

  17. Stimulus-evoked potentials contribute to map the epileptogenic zone during stereo-EEG presurgical monitoring.

    PubMed

    Boido, Davide; Kapetis, Dimos; Gnatkovsky, Vadym; Pastori, Chiara; Galbardi, Barbara; Sartori, Ivana; Tassi, Laura; Cardinale, Francesco; Francione, Stefano; de Curtis, Marco

    2014-09-01

    Presurgical monitoring with intracerebral electrodes in patients with drug-resistant focal epilepsy represents a standard invasive procedure to localize the sites of seizures origin, defined as the epileptogenic zone (EZ). During presurgical evaluation, intracerebral single-pulse electrical stimulation (SPES) is performed to define the boundaries of eloquent areas and to evoke seizure-associated symptoms. Extensive intracranial exploration and stimulation generate a large dataset on brain connectivity that can be used to improve EZ detection and to understand the organization of the human epileptic brain. We developed a protocol to analyse field responses evoked by intracranial stimulation. Intracerebral recordings were performed with 105-162 recording sites positioned in fronto-temporal regions in 12 patients with pharmacoresistant focal epilepsy. Recording sites were used for bipolar SPES at 1 Hz. Reproducible early and late phases (<60 ms and 60-500 ms from stimulus artefact, respectively) were identified on averaged evoked responses. Phase 1 and 2 responses recorded at all and each recording sites were plotted on a 3D brain reconstructions. Based on connectivity properties, electrode contacts were primarily identified as receivers, mainly activators or bidirectional. We used connectivity patterns to construct networks and applied cluster partitioning to study the proprieties between potentials evoked/stimulated in different regions. We demonstrate that bidirectional connectivity during phase 1 is a prevalent feature that characterize contacts included in the EZ. This study shows that the application of an analytical protocol on intracerebral stimulus-evoked recordings provides useful information that may contribute to EZ detection and to the management of surgical-remediable epilepsies. PMID:24706574

  18. 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.

  19. The effect of water maze spatial training on posterior parietal cortex transcallosal evoked field potentials in the rat.

    PubMed

    Beiko, J; Cain, D P

    1998-01-01

    Long-term potentiation (LTP) is the principal model of synaptic plasticity often used to explain the changes that occur in the brain as a result of learning and memory. In this experiment the relationship between rat posterior parietal cortex (PPC) transcallosal evoked field potentials (TCEPs) and spatial training in the water maze was examined to determine if LTP-like changes (i.e. learning-induced LTP) in PPC TCEPs occur as a result of spatial training. Spatial training consisted of 10 trials per day for 10 consecutive days. The location of the hidden platform was changed over the course of spatial training to ensure the rats' acquisition of several different platform positions. TCEPs were taken 1 and 23 h after each training session. Upon completion of all water maze training, the animals were administered LTP-inducing trains to ensure that the recording arrangement and procedure was capable of detecting LTP. The results showed that the rats quickly acquired the water maze task and that the recording arrangement and procedure were capable of detecting LTP, even after the first session of induction. However, despite robust place learning, the TCEPs taken after water maze training did not differ from those taken before water maze training. Although the present results failed to provide any evidence for a role of neocortical LTP in learning and memory, further studies of this nature are required to determine if the present results generalize to different behavioural tasks and/or cortical areas.

  20. 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

  1. The pattern visual evoked potential and pattern electroretinogram in drusen-associated optic neuropathy.

    PubMed

    Scholl, G B; Song, H S; Winkler, D E; Wray, S H

    1992-01-01

    Sixteen patients (29 eyes) with optic disc drusen were studied prospectively for clinical and electrophysiologic evidence of impaired optic nerve conduction. Abnormalities were detected in the following areas: visual acuity, eight (28%) of 29 eyes; kinetic visual field, 22 (76%) of 29 eyes; results of Farnsworth-Munsell 100-Hue test, 12 (41%) of 29 eyes; and flash visual evoked potential, 13 (54%) of 24 eyes. Simultaneous pattern visual evoked potentials and results of pattern electroretinograms were recorded. The P100 latency of the pattern visual evoked potential was prolonged in 41% of eyes. The P50 and N95 components of the pattern electroretinogram were also analyzed. The P50 amplitude was reduced in only four (17%) of 24 eyes. The most common abnormality was a reduction in amplitude or the absence of the N95 component in 19 (79%) of 24 eyes, reflecting ganglion cell dysfunction. The data support mounting evidence that the P50 and N95 components of the pattern electroretinogram have different retinal origins. PMID:1731726

  2. Abnormal visual evoked potentials in children with "Alice in Wonderland" syndrome due to infectious mononucleosis.

    PubMed

    Lahat, E; Berkovitch, M; Barr, J; Paret, G; Barzilai, A

    1999-11-01

    Visual illusions characterized by distortion of form, size, reciprocal position of objects, movement, or color, labeled as "Alice in Wonderland" syndrome, were discussed in children with infectious mononucleosis, as well as in other clinical conditions, such as migraine, epilepsy, use of certain hallucinogenic drugs, etc. The purpose of our study was to investigate for the first time visual evoked potential results in children with "Alice in Wonderland" syndrome associated with infectious mononucleosis. Five children with "Alice in Wonderland" syndrome associated with infectious mononucleosis underwent visual evoked potential studies during and after their clinical symptoms. Visual evoked potential results during the disease demonstrated statistically significant high amplitudes of P100-N145 in all children compared to the control group. A few weeks later, repeated studies after the resolution of the complaints were normal. Since the same findings can be observed in patients with migraine, we postulate that a common pathophysiologic underlying abnormality, which can cause transient focal decreased cerebral perfusion, could be involved in the disease process of these two conditions. PMID:10593551

  3. 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

  4. Peak morphology and scalp topography of the pharyngeal sensory evoked potential

    PubMed Central

    Wheeler-Hegland, Karen; Pitts, Teresa; Davenport, Paul W

    2016-01-01

    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 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 4 early and mid-latency components 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 fronto-parietal 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

  5. 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

  6. 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.

  7. 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

  8. Quantal evoked depolarizations underlying the excitatory junction potential of the guinea-pig isolated vas deferens

    PubMed Central

    Manchanda, Rohit; Venkateswarlu, K

    1999-01-01

    The effects of a putative gap junction uncoupling agent, heptanol, on the intracellularly recorded junction potentials of the guinea-pig isolated vas deferens have been investigated. After the stimulation-evoked excitatory junction potentials (EJPs) had been suppressed by heptanol (2.0 mm) to undetectable levels, a different pattern of evoked activity ensued. This consisted of transient depolarizations that were similar to EJPs in being stimulus locked and in occurring at a fixed latency, but differed from EJPs in that they occurred intermittently and had considerably briefer time courses. Analysis of the amplitudes and temporal parameters of the rapid residual depolarizations revealed a close similarity with spontaneous EJPs (SEJPs). There was no statistically significant difference between the rise times, time constants of decay and durations of the rapid residual depolarizations and of SEJPs. Selected evoked depolarizations were virtually identical to SEJPs occurring in the same cell. Evoked depolarizations of closely similar amplitude and time course also occurred, usually within a few stimuli of each other. These depolarizations appear to represent the individual quantal depolarizations that normally underlie the EJP and are therefore termed ‘quantal excitatory junction potentials’ (QEJPs) to distinguish them from both EJPs and SEJPs. We examined the possibility that heptanol revealed QEJPs by disrupting electrical coupling between cells in the smooth muscle syncytium. Heptanol (2.0 mm) had no effect on the amplitude distribution, time courses, or the frequency of occurrence of SEJPs. Intracellular input impedance (Rin) of smooth muscle cells was left unaltered by heptanol. ‘Cable’ potentials of the vas deferens, recorded using the partition stimulation method, also remained unchanged in the presence of heptanol. Thus, heptanol appeared not to modify syncytial electrical properties of the smooth muscle in any significant way. Our observations show

  9. 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

  10. 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

  11. Motor potentials evoked by navigated transcranial magnetic stimulation in healthy subjects.

    PubMed

    Säisänen, Laura; Julkunen, Petro; Niskanen, Eini; Danner, Nils; Hukkanen, Taina; Lohioja, Tarja; Nurkkala, Jouko; Mervaala, Esa; Karhu, Jari; Könönen, Mervi

    2008-12-01

    Navigated transcranial magnetic stimulation (TMS) is a tool for targeted, noninvasive stimulation of cerebral cortex. Transcranial stimuli can depolarize neurons and evoke measurable effects which are unique in two ways: the effects are caused directly and without a consciousness of the subject, and, the responses from peripheral muscles provide a direct measure for the integrity of the whole motor pathway. The clinical relevance of the method has not always been fully exposed because localizing the optimal stimulation site and determining the optimal stimulation strength have been dependent on time-consuming experimentation and skill. Moreover, in many disorders it has been uncertain, whether the lack of motor responses is the result of true pathophysiological changes or merely because of unoptimal stimulation. We characterized the muscle responses from human primary motor cortex system by navigated TMS to provide normative values for the clinically relevant TMS parameters on 65 healthy volunteers aged 22 to 81 years. We delivered focal TMS pulses on the primary motor area (M1) and recorded muscle responses on thenar and anterior tibial muscles. Motor threshold, latencies and amplitudes of motor-evoked potentials, and silent period duration were measured. The correction of the motor-evoked potential latency for subjects' height is provided. In conclusion, we provide a modified baseline of TMS-related parameters for healthy subjects. Earlier such large-scale baseline material has not been available.

  12. 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.

  13. [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

  14. The effect of changes in perilymphatic K+ on the vestibular evoked potential in the guinea pig.

    PubMed

    Kingma, C M; Wit, H P

    2010-11-01

    To investigate the effect on the functioning of the vestibular system of a rupture of Reissner's membrane, artificial endolymph was injected in scala media of ten guinea pigs and vestibular evoked potentials (VsEPs), evoked by vertical acceleration pulses, were measured. Directly after injection of a sufficient volume to cause rupture, all ears showed a complete disappearance of VsEP, followed by partial recovery. To investigate the effect of perilymphatic potassium concentration on the vestibular sensory and neural structures, different concentrations of KCl were injected directly into the vestibule. The KCl injections resulted in a dose-dependent decrease of VsEP, followed by a dose-dependent slow recovery. This animal model clearly shows a disturbing effect of a higher than normal K(+) concentration in perilymph on the vestibular and neural structures in the inner ear. Potassium intoxication is the most probable explanation for the observed effects. It is one of the explanations for Menière attacks.

  15. Different Stimulation Frequencies Alter Synchronous Fluctuations in Motor Evoked Potential Amplitude of Intrinsic Hand Muscles-a TMS Study.

    PubMed

    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.

  16. 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

  17. Spatial filtering based on canonical correlation analysis for classification of evoked or event-related potentials in EEG data.

    PubMed

    Spüler, Martin; Walter, Armin; Rosenstiel, Wolfgang; Bogdan, Martin

    2014-11-01

    Classification of evoked or event-related potentials is an important prerequisite for many types of brain-computer interfaces (BCIs). To increase classification accuracy, spatial filters are used to improve the signal-to-noise ratio of the brain signals and thereby facilitate the detection and classification of evoked or event-related potentials. While canonical correlation analysis (CCA) has previously been used to construct spatial filters that increase classification accuracy for BCIs based on visual evoked potentials, we show in this paper, how CCA can also be used for spatial filtering of event-related potentials like P300. We also evaluate the use of CCA for spatial filtering on other data with evoked and event-related potentials and show that CCA performs consistently better than other standard spatial filtering methods.

  18. 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

  19. Localizing Cortical Sources of Event-Related Potentials in Infants' Covert Orienting

    ERIC Educational Resources Information Center

    Richards, John E.

    2005-01-01

    This study used cortical source analysis to locate potential cortical sources of event-related potentials (ERPs) during covert orienting in infants aged 14 and 20 weeks. The infants were tested in a spatial cueing procedure. The reaction time to localize the target showed response facilitation for valid trials relative to invalid or neutral…

  20. Basic Principles and Recent Trends of Transcranial Motor Evoked Potentials in Intraoperative Neurophysiologic Monitoring.

    PubMed

    Tsutsui, Shunji; Yamada, Hiroshi

    2016-08-15

    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

  1. 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.

  2. 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

  3. Flash visual evoked potential monitoring of optic tract function during macroelectrode-based pallidotomy.

    PubMed

    Bonaroti, E A; Rose, R D; Kondziolka, D; Baser, S; Lunsford, L D

    1997-03-15

    Posteroventral pallidotomy (PVP) has received renewed interest as an ablative procedure for the symptomatic treatment of Parkinson's disease. In previous reports, the proximity of the optic tract to the lesion target in the globus pallidus internus has resulted in the occurrence of visual field deficits in as much as 14% of patients. The authors have used intraoperative visual evoked potentials (VEPs) during PVP to reduce this risk. All procedures were performed in awake patients. Flash stimuli were delivered to each eye via fiberoptic sources. Baseline flash VEPs were recorded at O1/Cz (left visual cortex to vertex), Oz/Cz (midline visual cortex to vertex), and O2/Cz (right visual cortex to vertex) for OS, OU, and OD stimulation. Epochs were acquired before and after localization, after macroelectrode stimulation, after temporary thermal lesioning, and after permanent thermal lesioning. Forty-seven patients underwent a total of 59 procedures. Visual evoked potentials were recorded reproducibly in all patients. In 11 procedures, VEP changes were reported, including six amplitude changes (10-80%), six latency shifts (3-10 msec), and one report of "variability." In four procedures, VEP changes prompted a change in target coordinates. One false-positive and one false-negative VEP change were encountered. The only confirmed visual deficit was a superior quadrantanopsia, present on formal fields, but clinically asymptomatic. The authors conclude that VEPs may be useful for procedures performed in the awake patient because of the lack of anesthetic-induced variability. The 1.7% visual morbidity reported here (one in 59 patients) compares favorably with other series using microelectrodes. Visual evoked potentials may be a useful monitoring technique to reduce the incidence of clinically significant visual morbidity during pallidotomy, especially during formal lesioning of the ventral pallidum adjacent to the optic tract.

  4. 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

  5. [Evoked potentials and brainstem reflex activity in patients of young and middle age with chronic headache].

    PubMed

    Kuznetsova, E A; Iakupov, E Z

    2011-01-01

    Neurophysiological peculiarities of functional state of afferent systems, including brain evoked potentials of different modalities and brainstem reflex activity, in patients of young and middle age with chronic headaches have been studied. In young patients, there was the increased reflex activity of visual and trigeminal systems, somatosensory cortex and brainstem structures that indicated the main role of the generator of pathologically increased excitation (GPIE) of different levels in the pathogenesis of chronic pain. In patients of middle age, we observed the predominant role of conduction delay on the supraspinal level. The revealed age-related neurophysiological peculiarities determine the pathogenetic therapy of chronic headaches.

  6. Somatosensory evoked potentials aid prediction after hypoxic-ischaemic brain injury.

    PubMed

    Kane, Nick; Oware, Agyepong

    2015-10-01

    Cardiopulmonary resuscitation, basic life support and early defibrillation are leading to more survivors of out-of-hospital cardiac arrest reaching hospital. Once stabilised on an intensive care unit, it can be difficult to predict the neurological outcome using clinical criteria alone, particularly with modern management using sedation, neuromuscular blockade and hypothermia. If we are to prevent ongoing futile life support, it is important to try to identify the majority of patients who, despite best efforts, will not make a meaningful recovery. Somatosensory evoked potentials are widely available electrophysiological tests that can provide an objective biomarker of a poor neurological outcome and assist in predicting the prognosis.

  7. Auditory evoked potential: a proposal for further evaluation in children with learning disabilities.

    PubMed

    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.

  8. Visual evoked potential latency and contrast sensitivity in patients with posterior chamber intraocular lens implants.

    PubMed Central

    Howe, J. W.; Mitchell, K. W.; Mahabaleswara, M.; Abdel-Khalek, M. N.

    1986-01-01

    An electrophysiological investigation of visual evoked potential (VEP) latency and contrast sensitivity was performed in a group of 13 patients who had undergone extracapsular cataract surgery with posterior chamber lens implantation. In spite of good postoperative visual acuity, abnormalities were detected in nine of the group (69%). This study suggests that, even with successfully implanted lenses, there may be a reduction in visual function which could be the result of altered transmission through the plastic lenticulus or fibrosis of the posterior lens capsule, and/or subtle changes in retinal architecture, not observed ophthalmoscopically. PMID:3801366

  9. 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.

  10. 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

  11. 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

  12. Assessment of an ICA-based noise reduction method for multi-channel auditory evoked potentials

    NASA Astrophysics Data System (ADS)

    Mirahmadizoghi, Siavash; Bell, Steven; Simpson, David

    2015-03-01

    In this work a new independent component analysis (ICA) based method for noise reduction in evoked potentials is evaluated on for auditory late responses (ALR) captured with a 63-channel electroencephalogram (EEG) from 10 normal-hearing subjects. The performance of the new method is compared with a single channel alternative in terms of signal to noise ratio (SNR), the number of channels with an SNR above an empirically derived statistical critical value and an estimate of hearing threshold. The results show that the multichannel signal processing method can significantly enhance the quality of the signal and also detected hearing thresholds significantly lower than with the single channel alternative.

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

    PubMed

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

    2014-01-01

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

  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.

  15. 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

  16. 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

  17. Visual evoked potentials in adrenoleukodystrophy: a trial with glycerol trioleate and Lorenzo oil.

    PubMed

    Kaplan, P W; Tusa, R J; Shankroff, J; Heller, J; Moser, H W

    1993-08-01

    Adrenoleukodystrophy is an X-linked metabolic disorder with very-long-chain fatty acid (VLCFA) accumulation and multifocal nervous system demyelination, often with early involvement of visual pathways. Dietary therapy with glycerol trioleate and glycerol trierucate (Lorenzo oil) diminishes VLCFA levels. In a study of patients with the adrenomyeloneuropathy phenotype of adrenoleukodystrophy, we used pattern-reversal visual evoked potentials to evaluate visual pathways before and after treatment. Of 108 patients tested, all 26 women and 68 of the 82 men had normal potentials at baseline. Seventy patients were retested at 1 year, at which time VLCFA levels were markedly diminished. Of them, the responses in the 10 men who showed abnormalities at baseline remained abnormal; the latencies in 4 men with initially normal responses became abnormal. No patients improved. There were no correlations between disease duration prior to treatment, baseline P100 latencies, VLCFA levels, or the change in P100 latencies and VLCFA levels after dietary treatment for 1 year. Pattern-reversal visual evoked potentials were abnormal in 17% of the men with adrenoleukodystrophy, and there was no evidence that reduction of VLCFA levels improved or retarded visual pathway demyelination.

  18. Evoked-potential audiogram of an Indo-Pacific humpback dolphin (Sousa chinensis).

    PubMed

    Li, Songhai; Wang, Ding; Wang, Kexiong; Taylor, Elizabeth A; Cros, Emilie; Shi, Wenjing; Wang, Zhitao; Fang, Liang; Chen, Yuefei; Kong, Fanming

    2012-09-01

    An evoked-potential audiogram was measured for an Indo-Pacific humpback dolphin (Sousa chinensis) living in the dolphinarium of Nanning Zoo, China. Rhythmic 20 ms pip trains composed of cosine-enveloped 0.25 ms tone pips at a pip rate of 1 kHz were presented as sound stimuli. The dolphin was trained to remain still at the water surface and to wear soft latex suction-cup EEG electrodes used to measure the animal's envelope-following evoked potentials to the sound stimuli. Responses to 1000 rhythmic 20 ms pip trains for each amplitude/frequency combination were averaged and analysed using a fast Fourier transform to obtain an evoked auditory response. The hearing threshold was defined as the zero crossing point of the response input-output function using linear regression. Fourteen frequencies ranging from 5.6 to 152 kHz were studied. The results showed that most of the thresholds were lower than 90 dB re. 1 μPa (r.m.s.), covering a frequency range from 11.2 to 128 kHz, and the lowest threshold of 47 dB was measured at 45 kHz. The audiogram, which is a function of hearing threshold versus stimulus carrier frequency, presented a U-shape with a region of high hearing sensitivity (within 20 dB of the lowest threshold) between approximately 20 and 120 kHz. At frequencies lower than this high-sensitivity region, thresholds increased at a rate of approximately 11 dB octave(-1) up to 93 dB at 5.6 kHz. The thresholds at high frequencies above 108 kHz increased steeply at a rate of 130 dB octave(-1) up to 127 dB at 152 kHz.

  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. 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. Bilaterally evoked monosynaptic EPSPs, NMDA receptors and potentiation in rat sympathetic preganglionic neurones in vitro.

    PubMed

    Spanswick, D; Renaud, L P; Logan, S D

    1998-05-15

    1. Whole-cell patch clamp and intracellular recordings were obtained from 190 sympathetic preganglionic neurones (SPNs) in spinal cord slices of neonatal rats. Fifty-two of these SPNs were identified histologically as innervating the superior cervical ganglion (SCG) by the presence of Lucifer Yellow introduced from the patch pipette and the appearance of retrograde labelling following the injection of rhodamine-dextran-lysine into the SCG. 2. Electrical stimulation of the ipsilateral (n = 71) or contralateral (n = 32) lateral funiculi (iLF and cLF, respectively), contralateral intermediolateral nucleus (cIML, n = 41) or ipsilateral dorsal horn (DH, n = 34) evoked EPSPs or EPSCs that showed a constant latency and rise time, graded response to increased stimulus intensity, and no failures, suggesting a monosynaptic origin. 3. In all neurones tested (n = 60), fast rising and decaying components of EPSPs or EPSCs evoked from the iLF, cLF, cIML and DH in response to low-frequency stimulation (0.03-0.1 Hz) were sensitive to non-NMDA receptor antagonists. 4. In approximately 50 % of neurones tested (n = 29 of 60), EPSPs and EPSCs evoked from the iLF, cLF, cIML and DH during low-frequency stimulation were reduced by NMDA receptor antagonists. In the remaining neurones, an NMDA receptor antagonist-sensitive EPSP or EPSC was revealed only in magnesium-free bathing medium, or following high-frequency stimulation. 5. EPSPs evoked by stimulation of the iLF exhibited a sustained potentiation of the peak amplitude (25.3 +/- 11.4 %) in six of fourteen SPNs tested following a brief high-frequency stimulus (10-20 Hz, 0.1-2 s). 6. These results indicate that SPNs, including SPNs innervating the SCG, receive monosynaptic connections from both sides of the spinal cord. The neurotransmitter mediating transmission in some of the pathways activated by stimulation of iLF, cLF, cIML and DH is glutamate acting via both NMDA and non-NMDA receptors. Synaptic plasticity is a feature of

  2. 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

  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.

  4. Evoked Potentials and Neuropsychological Tests Validate Positron Emission Topography (PET) Brain Metabolism in Cognitively Impaired Patients

    PubMed Central

    Braverman, Eric R.; Blum, Kenneth; Damle, Uma J.; Kerner, Mallory; Dushaj, Kristina; Oscar-Berman, Marlene

    2013-01-01

    Fluorodeoxyglucose (FDG) Positron Emission Topography (PET) brain hypometabolism (HM) correlates with diminished cognitive capacity and risk of developing dementia. However, because clinical utility of PET is limited by cost, we sought to determine whether a less costly electrophysiological measure, the P300 evoked potential, in combination with neuropsychological test performance, would validate PET HM in neuropsychiatric patients. We found that patients with amnestic and non-amnestic cognitive impairment and HM (n = 43) evidenced significantly reduced P300 amplitudes, delayed latencies, and neuropsychological deficits, compared to patients with normal brain metabolism (NM; n = 187). Data from patients with missing cognitive test scores (n = 57) were removed from the final sample, and logistic regression modeling was performed on the modified sample (n = 173, p = .000004). The logistic regression modeling, based on P300 and neuropsychological measures, was used to validate membership in the HM vs. NM groups. It showed classification validation in 13/25 HM subjects (52.0%) and in 125/148 NM subjects (84.5%), correlating with total classification accuracy of 79.8%. In this paper, abnormal P300 evoked potentials coupled with cognitive test impairment validates brain metabolism and mild/moderate cognitive impairment (MCI). To this end, we cautiously propose incorporating electrophysiological and neuropsychological assessments as cost-effective brain metabolism and MCI indicators in primary care. Final interpretation of these results must await required additional studies confirming these interesting results. PMID:23526928

  5. [Experience with flash-evoked visual potentials in unconscious patients in the neurologic intensive care station].

    PubMed

    Krieger, D; Adams, H P; Hacke, W

    1991-12-01

    Evoked potential monitoring has become a widely used procedure in the evaluation of stuporous patients on neurological intensive care units. Currently BAEP and SEP are preferentially employed. VEP monitoring is a relatively uncommon procedure, because late evoked potentials tend to be relatively unstable, varying in amplitude to a moderate extend from changes of temperature, drugs, attention and the level of consciousness. A valuable approach of VEP monitoring on intensive care units are structures of the visual system at risk in vascular disease of the vertebrobasilar system or during evaluated intracranial pressure (EIP). This study uses the data of 20 stuporous patients presenting with either intracranial mass lesions or vascular diseases of the vertebrobasilar system and 20 control persons. Light emitting diode (LED)-VEP are compared with checkerboard stimulation in control persons using the technique of cross-correlation. The comparison of the control group with patients using LED-VEP allows definition of limits for normal variation as a base for identification of significant changes. Despite methodical restrictions of LED-VEP, our results are in favour of serial studies in patients with EIP. There are no corresponding findings in LED-VEP and vascular lesions of the retrochiasmatic visual system.

  6. Hearing outcomes after loss of brainstem auditory evoked potentials during microvascular decompression.

    PubMed

    Thirumala, Parthasarathy D; Krishnaiah, Balaji; Habeych, Miguel E; Balzer, Jeffrey R; Crammond, Donald J

    2015-04-01

    The primary aim of this paper is to study the pre-operative characteristics, intra-operative changes and post-operative hearing outcomes in patients after complete loss of wave V of the brainstem auditory evoked potential. We retrospectively analyzed the brainstem auditory evoked potential data of 94 patients who underwent microvascular decompression for hemifacial spasm at our institute. Patients were divided into two groups - those with and those without loss of wave V. The differences between the two groups and outcomes were assessed using t-test and chi-squared tests. In our study 23 (24%) patients out of 94 had a complete loss of wave V, with 11 (48%) patients experiencing transient loss and 12 (52%) patients experiencing permanent loss. The incidence of hearing loss in patients with no loss of wave V was 5.7% and 26% in patients who did experience wave V loss. The incidence of hearing change in patients with no loss of wave V was 12.6% and 30.43% in patients who did experience wave V loss. Loss of wave V during the procedure or at the end of procedure significantly increases the odds of hearing loss. Hearing change is a significant under-reported clinical condition after microvascular decompression in patients who have loss of wave V.

  7. 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

  8. Effects of remote cutaneous pain on trigeminal laser-evoked potentials in migraine patients.

    PubMed

    de Tommaso, Marina; Difruscolo, Olimpia; Sardaro, Michele; Libro, Giuseppe; Pecoraro, Carla; Serpino, Claudia; Lamberti, Paolo; Livrea, Paolo

    2007-06-01

    The present study aimed to evaluate heat pain thresholds and evoked potentials following CO(2) laser thermal stimulation (laser-evoked potentials, LEPs), during remote application of capsaicin, in migraine patients vs. non-migraine healthy controls. Twelve outpatients suffering from migraine without aura were compared with 10 healthy controls. The LEPs were recorded by 6 scalp electrodes, stimulating the dorsum of the right hand and the right supraorbital zone in basal condition, during the application of 3% capsaicin on the dorsum of the left hand and after capsaicin removal. In normal subjects, the laser pain and the N2-P2 vertex complex obtained by the hand and face stimulation were significantly reduced during remote capsaicin application, with respect to pre-and post-capsaicin conditions, while in migraine LEPs and laser pain were not significantly modified during remote painful stimulation. In migraine a defective brainstem inhibiting control may coexist with cognitive factors of focalised attention to facial pain, less sensitive to distraction by a second pain. PMID:17563842

  9. Effects of remote cutaneous pain on trigeminal laser-evoked potentials in migraine patients.

    PubMed

    de Tommaso, Marina; Difruscolo, Olimpia; Sardaro, Michele; Libro, Giuseppe; Pecoraro, Carla; Serpino, Claudia; Lamberti, Paolo; Livrea, Paolo

    2007-06-01

    The present study aimed to evaluate heat pain thresholds and evoked potentials following CO(2) laser thermal stimulation (laser-evoked potentials, LEPs), during remote application of capsaicin, in migraine patients vs. non-migraine healthy controls. Twelve outpatients suffering from migraine without aura were compared with 10 healthy controls. The LEPs were recorded by 6 scalp electrodes, stimulating the dorsum of the right hand and the right supraorbital zone in basal condition, during the application of 3% capsaicin on the dorsum of the left hand and after capsaicin removal. In normal subjects, the laser pain and the N2-P2 vertex complex obtained by the hand and face stimulation were significantly reduced during remote capsaicin application, with respect to pre-and post-capsaicin conditions, while in migraine LEPs and laser pain were not significantly modified during remote painful stimulation. In migraine a defective brainstem inhibiting control may coexist with cognitive factors of focalised attention to facial pain, less sensitive to distraction by a second pain.

  10. Correlation between acceleration magnitude and ocular vestibular-evoked myogenic potential.

    PubMed

    Wang, Shou-Jen; Jaw, Fu-Shan; Young, Yi-Ho

    2012-05-10

    This study combined bone-conducted vibration (BCV) stimulation with triaxial accelerometry to correlate the acceleration magnitudes of BCV stimuli with ocular vestibular-evoked myogenic potential (oVEMP) test results. Fourteen healthy volunteers underwent oVEMP test using BCV stimuli with simultaneous monitoring the triaxial acceleration. All (100%) subjects exhibited clear oVEMPs in response to BCV stimuli from a vibrator. The lowest acceleration magnitudes for eliciting oVEMPs along the x-, y- and z-axes were 0.05±0.01 g, 0.16±0.08 g, and 0.04±0.01 g, respectively, exhibiting significantly higher acceleration magnitude along the y-axis than those along the x- and z-axes. In addition, significantly positive correlations were noted between the acceleration magnitude along each axis and the oVEMP amplitude. In conclusion, measuring the acceleration magnitude throughout oVEMP testing revealed a significant correlation between linear acceleration and oVEMP responses. Restated, increasing acceleration magnitude may have more synchronization of firing of vestibular afferents, resulting in more synchronized evoked potentials and greater oVEMP amplitude.

  11. 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.

  12. 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

  13. 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

  14. Pericellular Ca2+ recycling potentiates thrombin-evoked Ca2+ signals in human platelets

    PubMed Central

    Sage, Stewart O; Pugh, Nicholas; Farndale, Richard W; Harper, Alan G S

    2013-01-01

    We have previously demonstrated that Na+/Ca2+ exchangers (NCXs) potentiate Ca2+ signaling evoked by thapsigargin in human platelets, via their ability to modulate the secretion of autocoids from dense granules. This link was confirmed in platelets stimulated with the physiological agonist, thrombin, and experiments were performed to examine how Ca2+ removal by the NCX modulates platelet dense granule secretion. In cells loaded with the near-membrane indicator FFP-18, thrombin stimulation was observed to elicit an NCX-dependent accumulation of Ca2+ in a pericellular region around the platelets. To test whether this pericellular Ca2+ accumulation might be responsible for the influence of NCXs over platelet function, platelets were exposed to fast Ca2+ chelators or had their glycocalyx removed. Both manipulations of the pericellular Ca2+ rise reduced thrombin-evoked Ca2+ signals and dense granule secretion. Blocking Ca2+-permeable ion channels had a similar effect, suggesting that Ca2+ exported into the pericellular region is able to recycle back into the platelet cytosol. Single cell imaging with extracellular Fluo-4 indicated that thrombin-evoked rises in extracellular [Ca2+] occurred within the boundary described by the cell surface, suggesting their presence within the open canalicular system (OCS). FFP-18 fluorescence was similarly distributed. These data suggest that upon thrombin stimulation, NCX activity creates a rise in [Ca2+] within the pericellular region of the platelet from where it recycles back into the platelet cytosol, acting to both accelerate dense granule secretion and maintain the initial rise in cytosolic [Ca2+]. PMID:24303163

  15. Topographic recordings of auditory evoked potentials to speech: subcortical and cortical responses.

    PubMed

    Bellier, Ludovic; Bouchet, Patrick; Jeanvoine, Arnaud; Valentin, Olivier; Thai-Van, Hung; Caclin, Anne

    2015-04-01

    Topographies of speech auditory brainstem response (speech ABR), a fine electrophysiological marker of speech encoding, have never been described. Yet, they could provide useful information to assess speech ABR generators and better characterize populations of interest (e.g., musicians, dyslexics). We present here a novel methodology of topographic speech ABR recording, using a 32-channel low sampling rate (5 kHz) EEG system. Quality of speech ABRs obtained with this conventional multichannel EEG system were compared to that of signals simultaneously recorded with a high sampling rate (13.3 kHz) EEG system. Correlations between speech ABRs recorded with the two systems revealed highly similar signals, without any significant difference between their signal-to-noise ratios (SNRs). Moreover, an advanced denoising method for multichannel data (denoising source separation) significantly improved SNR and allowed topography of speech ABR to be recovered.

  16. Are flash-evoked visual potentials useful for intraoperative monitoring of visual pathway function?

    PubMed

    Cedzich, C; Schramm, J; Fahlbusch, R

    1987-11-01

    Flash-evoked visual potentials (VEPs) recorded from the scalp were used in a series of 35 patients with tumors along the visual pathway: 3 orbital tumors, 25 perisellar tumors, 4 intraventricular tumors, and 3 occipital lesions. Preoperatively, various combinations of impaired visual fields and visual acuity were observed in over 90% of the patients. A postoperative decrease in visual function was observed in 3 cases. Of the 25 perisellar lesions, 13 were operated through a standard frontotemporal craniotomy and 12 were operated through a transnasal-transsphenoidal approach. VEPs were highly susceptible to volatile anesthetics, and there was a significant incidence of spontaneous latency increases and amplitude decreases in a large number of patients. There was an unacceptably high number of cases with significant VEP alteration occurring without concomitant visual function change. During trepanation or the transnasal approach, a reversible potential loss was observed in 11 patients, a profoundly altered wave form was seen in 8 cases, and a loss of single peaks was observed in 15 patients. During dissection of the tumor, a reversible potential loss or a potential with unidentifiable peaks was found in 25 cases; however, the VEPs recovered during closure or in the recovery room. There was no correlation between intraoperative VEP changes and the postoperative changes in visual function. In only 1 patient with an insignificant postoperative decrease in visual acuity from 0.4 to 0.3 was there a concomitant intraoperative potential loss. The major conclusion of our findings is that light-emitting diode flash-evoked VEPs demonstrate intraoperative changes that appear too early and too prominently to be caused solely by manipulation of the optic pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. 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

  18. 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

  19. 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

  20. Post-tetanic mechanical tension and evoked action potentials in McArdle's disease

    PubMed Central

    Brandt, N. J.; Buchthal, F.; Ebbesen, F.; Kamieniecka, Z.; Krarup, C.

    1977-01-01

    The tension produced by the cramp evoked in the adductor pollicis muscle by repetitive stimuli to the nerve (20/s for 50 s) and by full voluntary effort in the brachial biceps was measured in a patient with McArdle's disease. The contracture was 17% of the peaktetanic tension, and was not associated with action potentials. Twitches superimposed on the contracture were at most diminished to half, as were their action potentials. Both slow and fast muscle fibres participated in the contracture. The contraction time of the twitches elicited after the tetanus was prolonged more in the patient than in a normal subject of the same age. There was evidence of delayed firing, first observed 90 seconds after the peak of the contracture. The patient had electromyographic and histological signs of myopathy. PMID:271684

  1. Effect of raising body temperature on visual and somatosensory evoked potentials in patients with multiple sclerosis.

    PubMed

    Matthews, W B; Read, D J; Pountney, E

    1979-03-01

    The effects of raising body temperature on the visual (VEP) and somatosensory (SEP) evoked potentials were observed in normal subjects and in patients with multiple sclerosis. The amplitude of the VEP was significantly reduced to the same degree after heating in normal subjects and in patients with multiple sclerosis but there was no effect on the latency of the potential. Changes in amplitude could not be related to reduction in acuity. In contrast, the cervical SEP was greatly disorganised after heating in many patients with multiple sclerosis while the only effect in normal subjects was to reduce the latency by increasing peripheral conduction velocity. These results suggest that heat caused conduction block in demyelinated axons in the sensory pathways of the cervical spinal cord.

  2. [Development of auditory evoked potentials of the brainstem in relation to age].

    PubMed

    Tarantino, V; Stura, M; Vallarino, R

    1988-01-01

    In order to study the various changes which occur in the waveform, latency and amplitude of the auditory brainstem evoked response (BSER) as a function of age, the authors recorded the BSER from the scalp's surface of 20 newborns and 50 infants, 3 months, 6 months, 1 year and 3 years old as well as from 20 normal adults. The data obtained show that the most reliable waves during the first month of life are waves I, III, V, which is often present even when other vertex-positive peaks are absent. The latencies of the various potential components decreased with maturation. Wave V, evoked by 90 dB sensation level clicks, changed in latency from 7, 12 msec at 1-4 weeks of age to 5,77 msec at 3 years of life. The auditory processes related to peripheral and central transmission were shown to mature at differential rates during the first period of life. By the 6th month, in fact, wave I latency had reached the adult value; in contrast, wave V latency did match that of the adult until approximately 1 year old. One obvious explanation for the age-related latency shift is progressive myelination of the auditory tract in infants, for this is know to occur. The authors conclude that the clinical application of this technique in paediatric patients couldn't provide reliable informations about auditory brain stem activity regardless of evaluation of the relationship between age and characteristics of BSER.

  3. 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.

  4. Frequency specificity of simultaneously recorded early and middle latency auditory evoked potentials.

    PubMed

    Scherg, M; Volk, S A

    1983-11-01

    Early and middle latency auditory evoked potentials were recorded simultaneously with a 2-channel wide-band recording technique. Latency and amplitude distributions of components V, Na and Pa were determined in 20 normal hearing adults for 3 different stimuli (click, plop, 500 Hz tone burst) presented at 70, 30 and 20 dB HL. Normative latency data of the middle latency components are presented. The detectability and amplitude of the Na-Pa complex were considerably larger than those of wave V at 20 and 30 dB HL for the two low frequency stimuli. Ten ears exhibiting high frequency sensorineural hearing loss were examined. In these cases, only click-evoked Na and Pa, but not wave V, were observed down to 20 dB HL. Also, the click latency-intensity function of Na-Pa was found to be similar to the normal low frequency latency functions. The results consistently suggested that the low frequency contributions to wave V cancel in phase because of short duration, whereas the duration of the Na-Pa complex allows for a positive superimposition of all frequency bands. Since these differences in frequency specificity of the EAEP and the MAEP affect latency, care is advised for the interpretation of inter-peak latencies.

  5. 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

  6. Interactions Between Dyspnea and the Brain Processing of Nociceptive Stimuli: Experimental Air Hunger Attenuates Laser-Evoked Brain Potentials in Humans.

    PubMed

    Dangers, Laurence; Laviolette, Louis; Similowski, Thomas; Morélot-Panzini, Capucine

    2015-01-01

    Dyspnea and pain share several characteristics and certain neural networks and interact with each other. Dyspnea-pain counter-irritation consists of attenuation of preexisting pain by intercurrent dyspnea and has been shown to have neurophysiological correlates in the form of inhibition of the nociceptive spinal reflex RIII and laser-evoked potentials (LEPs). Experimentally induced exertional dyspnea inhibits RIII and LEPs, while "air hunger" dyspnea does not inhibit RIII despite its documented analgesic effects. We hypothesized that air hunger may act centrally and inhibit LEPs. LEPs were obtained in 12 healthy volunteers (age: 21-29) during spontaneous breathing (FB), ventilator-controlled breathing (VC) tailored to FB, after inducing air hunger by increasing the inspired fraction of carbon dioxide -FiCO2- (VCCO2), and during ventilator-controlled breathing recovery (VCR). VCCO2 induced intense dyspnea (visual analog scale = 63% ± 6% of full scale, p < 0.001 vs. VC), predominantly of the air hunger type. VC alone reduced the amplitude of the N2-P2 component of LEPs (Δ = 24.0% ± 21.1%, p < 0.05, effect-size = 0.74) predominantly through a reduction in P2, and the amplitude of this inhibition was further reduced by inducting air hunger (Δ = 22.6% ± 17.9%, p < 0.05, effect-size = 0.53), predominantly through a reduction in N2. Somatosensory-evoked potentials (SEPs) were not affected by VC or VCCO2, suggesting that the observed effects are specific to pain transmission. We conclude that air hunger interferes with the cortical mechanisms responsible for the cortical response to painful laser skin stimulation, which provides a neurophysiological substrate to the central nature of its otherwise documented analgesic effects. PMID:26648875

  7. 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

  8. Neural Consequences of Increasing Body Weight: Evidence from Somatosensory Evoked Potentials and the Frequency-Specificity of Brain Oscillations.

    PubMed

    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

  9. 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

  10. 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.

  11. Temperature dependence and independence of effects of pentobarbital on visual evoked potentials of rats.

    PubMed

    Hetzler, B E; Krekow, L K

    1999-01-01

    Visual cortex flash evoked potentials (FEPs), pattern reversal evoked potentials (PREPs), and body temperature were measured in hooded rats following IP injections on separate days of saline, and of 15 and 30 mg pentobarbital/kg body weight. Two experiments were performed, differentiated by standard (23 degrees C) and warm (31 degrees C) room temperatures. The 30 mg/kg dose produced hypothermia of 2.6 degrees C in the standard environment, but not in the warm environment. Early components of FEPs were generally increased in amplitude by the 15 mg/kg dose, and decreased by the 30 mg/kg dose at 23 degrees C. At 31 degrees C, the 30 mg/kg dose did not decrease early component amplitude, suggesting that hypothermia can potentiate some effects of pentobarbital. Amplitudes of late FEP components were depressed at both ambient temperatures. The main PREP components N1P1 and P1N3 were increased in amplitude by the 15 mg/kg dose, but returned to near baseline levels at 30 mg/kg, at both temperatures. PREP component N2P2 was reduced in amplitude by the 30 mg/kg dose only at 23 degrees C. Treatment with 30 mg/kg pentobarbital increased FEP and PREP latencies at both ambient temperatures, but the magnitudes of the increases at 31 degrees C were typically less than half those observed at 23 degrees C. These results indicate that hypothermia contributes to some pentobarbital-induced changes in both FEPs and PREPs, but that pentobarbital also produces effects independent of hypothermia.

  12. [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

  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. Effect of noise on the vestibular system - Vestibular evoked potential studies in rats.

    PubMed

    Sohmer, H.; Elidan, J.; Plotnik, M.; Freeman, S.; Sockalingam, R.; Berkowitz, Z.; Mager, M.

    1999-01-01

    Studies have shown that in order for sound to affect the vestibular end organs in the inner ear, very high intensities are required. Furthermore, in patients with noise induced hearing loss, vestibular signs, if present, are subclinical. In order to study possible auditory-vestibular interactions in a more controlled fashion, using physiological sound intensities, the present study used short latency vestibular evoked potentials (VsEPs) to impulses of angular (15,000 degrees /sec(2), risetime 1.5 msec) and linear (3-5 g, risetime 1.5 msec) acceleration were used to study the possible effects of sound on peripheral vestibular function in rats. Four different paradigms were used: a - an intense (135 dB pe SPL) click stimulus was presented 5 msec before the linear acceleration impulse and the VsEP to 128 stimuli were recorded with and without this click stimulus. There was no effect of the preceding intense click on the first wave (reflecting end organ activity) of the linear VsEP. b - 113 dB SPL white noise "masking" was presented while the VsEPs were elicited. A 10-20% reduction in the amplitude of the first VsEP wave was seen during the noise exposure, but 5 minutes after this exposure, there was almost complete recovery to pre-exposure amplitude. c - 113 dB SPL noise was presented for one hour and VsEPs were recorded within 15 minutes of cessation of the noise. The auditory nerve-brainstem-evoked response showed a temporary threshold shift while there was no effect on the VsEP. d - 113 dB SPL white noise was presented for 12 hours per day for 21 consecutive days. Auditory nerve-brainstem-evoked responses and vestibular (VsEPs) function were studied one week after the conclusion of the noise exposure. Auditory function was severely permanently depressed (40 dB threshold elevation and clear histological damage) while the amplitude of wave 1 of the VsEP was not affected. It seems therefore that even though intense noise clearly affects the cochlea and may have a

  15. Effects of cigarette smoking on resting EEG, visual evoked potentials and photic driving.

    PubMed

    Golding, J F

    1988-01-01

    The effects of smoking a cigarette (1.3 mg nicotine delivery) versus sham smoking were studied using EEG, visual evoked potentials (VEP), photic driving (PD) and heart rate (HR) in thirty young healthy male and female habitual cigarette smokers. Heart rate (HR) and exhaled carbon monoxide (CO) level were significantly increased by real as opposed to sham smoking. Real versus sham smoking significantly increased relative power in the beta bands, reduced alpha and theta activity to a small but significant extent, but had no effect on delta activity. Dominant EEG alpha frequency was significantly increased by real as opposed to sham smoking. Smoking produced no significant mean change in PD or VEP. However, correlational analysis indicated that variables such as basal CO level, residual butt filter nicotine, basal electrocortical response level and personality, predicted to varying degrees the magnitude and direction of the effect of smoking on VEP, PD and EEG.

  16. Statistical Modeling and Analysis of Laser-Evoked Potentials of Electrocorticogram Recordings from Awake Humans

    PubMed Central

    Chen, Zhe; Ohara, Shinji; Cao, Jianting; Vialatte, François; Lenz, Fred A.; Cichocki, Andrzej

    2007-01-01

    This article is devoted to statistical modeling and analysis of electrocorticogram (ECoG) signals induced by painful cutaneous laser stimuli, which were recorded from implanted electrodes in awake humans. Specifically, with statistical tools of factor analysis and independent component analysis, the pain-induced laser-evoked potentials (LEPs) were extracted and investigated under different controlled conditions. With the help of wavelet analysis, quantitative and qualitative analyses were conducted regarding the LEPs' attributes of power, amplitude, and latency, in both averaging and single-trial experiments. Statistical hypothesis tests were also applied in various experimental setups. Experimental results reported herein also confirm previous findings in the neurophysiology literature. In addition, single-trial analysis has also revealed many new observations that might be interesting to the neuroscientists or clinical neurophysiologists. These promising results show convincing validation that advanced signal processing and statistical analysis may open new avenues for future studies of such ECoG or other relevant biomedical recordings. PMID:18369410

  17. Respiratory sensory gating measured by respiratory-related evoked potentials in generalized anxiety disorder.

    PubMed

    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.

  18. Electrically evoked potentials in an ovine model for the evaluation of visual prosthesis efficacy.

    PubMed

    Barriga-Rivera, Alejandro; Eiber, Calvin D; Dodds, Christopher W D; Fung, Adrian T; Tatarinoff, Veronica; Lovell, Nigel H; Suaning, Gregg J

    2015-01-01

    Visual prostheses are becoming a reality as a therapy to restore functional vision to the blind. New stimulation strategies and novel electrode designs are contributing to accelerate the development of such devices triggering the interest of scientists, clinicians and the blind community worldwide. In this scenario, there is a need for large animal models that are suitable for preclinical testing of retinal neuroprostheses. This study presents an electrophysiology assessment of an ovine model for single and simultaneous electrode stimulation from the suprachoroidal space, using symmetric biphasic current pulses with a monopolar return configuration. Visually and electrically evoked potentials were recorded using supradural surface electrodes, showing charge thresholds comparable to those in humans. This model represents an alternative to feline or canine models with analogous activation levels and an eye anatomy similar to that of humans.

  19. 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.

  20. [Increase in intracranial pressure in monitoring brain stem auditory evoked potentials using headphones].

    PubMed

    Schwarz, G; Pfurtscheller, G; Tritthart, H; List, W F

    1988-11-01

    Ten measurements of intracranial pressure (ICP) (ventricular n = 5, epidural n = 3) in 8 patients (3 after aneurysm surgery, 5 with head trauma) were performed before and after application of conventional headphones for stimulating brainstem auditory evoked potentials (BAEP). The effects of miniature earphones and sound tubes on ICP were also studied. In 7 of 10 measurements after application of headphones a reversible increase of ICP (mean 26 +/- 19% in patients with ICP greater than 10 mmHg was recorded; in 3 patients (ICP less than or equal to 10 mgHg) no changes of ICP were seen. Using miniature earphones and sound tubes no increase of ICP was noted in any patient, and hence these can be recommended for stimulating BAEP in case of increased ICP.

  1. Visual evoked potentials to lateralised stimuli in two cases of callosal agenesis.

    PubMed Central

    Rugg, M D; Milner, A D; Lines, C R

    1985-01-01

    Visual evoked potentials (VEPs) to lateralised light flashes were recorded from two acallosal patients. In one patient, these recordings were made while he performed a choice-reaction time task, and in the other patient the VEPs were obtained during a simple reaction time task. In both cases the patient's VEPs from electrode sites contralateral to the visual field of stimulus delivery resembled those of controls. Their VEPs from ipsilateral sites were aberrant, however, in that while control subjects showed a smaller and slightly delayed ipsilateral N160 component, this was not discernible in the patients' data. It is concluded that the ipsilateral N160 relies for its generation on the transcallosal transfer of information processed initially by the contralateral hemisphere. PMID:3998742

  2. Value of visual evoked potential monitoring during trans-sphenoidal pituitary surgery.

    PubMed

    Chacko, A G; Babu, K S; Chandy, M J

    1996-06-01

    The visual outcome of 22 patients undergoing trans-sphenoidal excision of pituitary macroadenomas with intraoperative flash visual evoked potential (VEP) monitoring (Group A), was compared with a non-randomized group of 14 patients who had undergone similar operations without VEP monitoring (Group B). Tumour size, preoperative visual acuity, peripheral fields, and latencies and amplitudes of P1 and P2 were analysed to ascertain the best predictor of postoperative visual function. It was found that patients in Group A had a significantly greater improvement in field defects than those in Group B. There was no difference in postoperative improvement in visual acuity between the two groups. None of the variables analysed were good predictors of visual outcome.

  3. A computational model for generation of the P300 evoked potential component.

    PubMed

    Bonala, Bharat K; Jansen, Ben H

    2012-09-01

    The P300 is an endogenously evoked potential with amplitude and latency depending on the amount of information carried by the stimulus rather than its physical characteristics. It has been suggested that P300 is a manifestation of the context updating mechanism in the human working memory. We present a neural network-based model that mimics the learning and forgetting mechanisms of external stimuli in the human working memory that are believed to be responsible for P300 generation. A modified version of the Hebbian learning rule has been devised to govern the weight dynamics of the network. The model was validated by comparing the characteristics of simulated P300 with actual experimental findings such as the relationship between P300 amplitude and stimulus probability, and task relevance. The results show that the proposed P300 model mimics many aspects of the nervous system responsible for P300 generation. PMID:22974337

  4. 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.

  5. Does athletic training in volleyball modulate the components of visual evoked potentials? A preliminary investigation.

    PubMed

    Zwierko, Teresa; Lubiński, Wojciech; Lesiakowski, Piotr; Steciuk, Hanna; Piasecki, Leszek; Krzepota, Justyna

    2014-01-01

    This longitudinal study investigated visual evoked potentials (VEPs) in 11 young female volleyball players who participated in extensive training for 2 years. The control group consisted of 7 age-matched female students who were not involved in any regular sports activity. Recordings of VEPs were performed twice: baseline recording (i.e., before training began) and after 2 years of systematic, volleyball-specific athletic training. The effect of athletic training on visual signal conductivity was assessed by recording the latency of N75, P100 and N135 components of the VEPs waveform. Extensive experience with volleyball training reduced signal conductivity time through visual pathway. Specifically, the latency of P100 was reduced on average by 2.2 ms during binocular viewing. Moreover, athletes had reduced N75 latency (difference of 3.3 ms) for visual stimuli that generated greater response from peripheral retina. These results indicate that sport training can affect very early sensory processing in athletes.

  6. Possible long term effects of chemical warfare using visual evoked potentials.

    PubMed

    Riazi, Abbas; Hafezi, Rhamatollah; Babaei, Mahmoud; Naderi, Mostafa

    2014-09-01

    Some studies have already addressed the effects of occupational organic solvent exposure on the visually evoked potentials (VEPs). Visual system is an important target for Sulphur Mustard (SM) toxicity. A number of Iranian victims of Sulphur Mustard (SM) agent were apprehensive about the delay effect of SM on their vision and a possible delay effect of SM on their visual cortex. This investigation was performed on 34 individuals with a history of chemical exposure and a control group of 15 normal people. The Toennies electro-diagnosis device was used and its signals were saved as the latencies. The mean of N75, N140 and P100 of victims of chemical warfare (VCWs) and control group indicated no significant results (P>0.05). The VCWs did not show any visual symptoms and there was no clear deficit in their VEPs.

  7. 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.

  8. Postoperative changes in visual evoked potentials and cognitive function tests following sevoflurane anaesthesia.

    PubMed

    Iohom, G; Collins, I; Murphy, D; Awad, I; O'Connor, G; McCarthy, N; Shorten, G

    2001-12-01

    We tested the hypothesis that minor disturbance of the visual pathway persists following general anaesthesia even when clinical discharge criteria are met. To test this, we measured visual evoked potentials (VEPs) in 13 ASA I or II patients who did not receive any pre-anaesthetic medication and underwent sevoflurane anaesthesia. VEPs were recorded on four occasions, before anaesthesia and at 30, 60, and 90 min after emergence from anaesthesia. Patients completed visual analogue scales (VAS) for sedation and anxiety, a Trieger Dot Test (TDT) and a Digit Symbol Substitution Test (DSST) immediately before each VEP recording. These results were compared using Student's t-test. P<0.05 was considered significant. VEP latency was prolonged (P<0.001) and amplitude diminished (P<0.05) at 30, 60, and 90 min after emergence from anaesthesia, when VAS scores for sedation and anxiety, TDT, and DSST had returned to pre-anaesthetic levels. PMID:11878686

  9. Changes in visual evoked potentials in children on chronic dialysis treatment.

    PubMed

    Ducati, A; Cattarelli, D; Cenzato, M; Landi, A; Edefonti, A; Capitanio, L; Pavani, M; Villani, R

    1985-01-01

    Visual evoked potentials (VEP) were recorded in 20 children undergoing dialysis for chronic renal failure. VEP before treatment (72 h after last dialysis) were pathological in 17 patients (85%); responses obtained 3 h after treatment were abnormal in only 6 cases (30%). Furthermore, all patients improved after treatment, except two who were unchanged. However, VEP recorded immediately after dialysis were worse in 4 of 7 patients than before treatment, probably as an effect of the dysequilibrium syndrome; they improved spontaneously afterwards. The acute changes caused by dialysis seem to be more evident in children than in adults. No correlations have been found between blood chemistry indexes and VEP modifications. Finally, VEP have proved to be more sensitive than EEG in identifying a central nervous system (CNS) dysfunction in these uremic patients.

  10. Effect of refractive error on visual evoked potentials with pattern stimulation in dogs

    PubMed Central

    ITO, Yosuke; MAEHARA, Seiya; ITOH, Yoshiki; MATSUI, Ai; HAYASHI, Miri; KUBO, Akira; UCHIDE, Tsuyoshi

    2015-01-01

    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

  11. 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.

  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

    2014-05-14

    Although noise has a proven beneficial role in brain functions, there have not been any attempts on the dedication of stochastic resonance effect in neural engineering applications, especially in researches of brain-computer interfaces (BCIs). In our study, a steady-state motion visual evoked potential (SSMVEP)-based BCI with periodic visual stimulation plus moderate spatiotemporal noise can achieve better offline and online performance due to enhancement of periodic components in brain responses, which was accompanied by suppression of high harmonics. Offline results behaved with a bell-shaped resonance-like functionality and 7-36% online performance improvements can be achieved when identical visual noise was adopted for different stimulation frequencies. Using neural encoding modeling, these phenomena can be explained as noise-induced input-output synchronization in human sensory systems which commonly possess a low-pass property. Our work demonstrated that noise could boost BCIs in addressing human needs.

  13. Multimodal electrophysiological studies including motor evoked potentials in patients with locked-in syndrome: report of six patients.

    PubMed Central

    Bassetti, C; Mathis, J; Hess, C W

    1994-01-01

    Clinical and electrophysiological findings in six patients with locked-in syndrome are reported. Motor evoked potentials (MEPs) after magnetic stimulation of the motor cortex were absent in four patients, none of whom recovered clinically. In two patients, MEPs could be obtained from the severely paretic limbs and almost full motor recovery followed. Somatosensory evoked potentials were altered in four of the patients, and brainstem auditory evoked potentials were altered in two of four patients examined, showing a clinically unsuspected tegmental involvement. The EEG showed a predominance of reactive alpha activity in all patients, documenting a preserved consciousness. It is concluded that a multimodal electrophysiological approach, in addition to clinical assessment, can be helpful in diagnosing locked-in syndrome, estimating the extension of the underlying brainstem dysfunction, and predicting functional outcome. Images PMID:7964820

  14. Electrically Elicited Visual Evoked Potentials in Argus II Retinal Implant Wearers

    PubMed Central

    Stronks, H. Christiaan; Barry, Michael P.; Dagnelie, Gislin

    2013-01-01

    Purpose. We characterized electrically elicited visual evoked potentials (eVEPs) in Argus II retinal implant wearers. Methods. eVEPs were recorded in four subjects, and analyzed by determining amplitude and latency of the first two positive peaks (P1 and P2). Subjects provided subjective feedback by rating the brightness and size of the phosphenes. We established eVEP input–output relationships, eVEP variability between and within subjects, the effect of stimulating different areas of the retina, and the maximal pulse rate to record eVEPs reliably. Results. eVEP waveforms had low signal-to-noise ratios, requiring long recording times and substantial signal processing. Waveforms varied between subjects, but showed good reproducibility and consistent parameter dependence within subjects. P2 amplitude overall was the most robust outcome measure and proved an accurate indicator of subjective threshold. Peak latencies showed small within-subject variability, yet their correlation with stimulus level and subjective rating were more variable than that of peak amplitudes. Pulse rates of up to 2/3 Hz resulted in reliable eVEP recordings. Perceived phosphene brightness declined over time, as reflected in P1 amplitude, but not in P2 amplitude or peak latencies. Stimulating-electrode location significantly affected P1 and P2 amplitude and latency, but not subjective percepts. Conclusions. While recording times and signal processing are more demanding than for standard visually evoked potential (VEP) recordings, the eVEP has proven to be a reliable tool to verify retinal implant functionality. eVEPs correlated with various stimulus parameters and with perceptual ratings. In view of these findings, eVEPs may become an important tool in functional investigations of retinal prostheses. (ClinicalTrials.gov number NCT00407602.) Dutch Abstract PMID:23611993

  15. Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency

    PubMed Central

    Subramanian, Senthil Kumar; Gaur, Giriwar Singh; Narayan, Sunil K.

    2013-01-01

    Context: Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP), though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects. Aim: To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs. Subjects and Methods: Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique). Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day. Statistical Analysis: Variation in FVEP latencies between the individuals (interindividual variability) and the variations within the same individual for four trials (intraindividual variability) were assessed using coefficient of variance (COV). The technique with lower COV was considered the better method. Results: Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red) showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques. Conclusions: Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique. PMID:24339591

  16. 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

  17. Broad-Band Visually Evoked Potentials: Re(con)volution in Brain-Computer Interfacing

    PubMed Central

    Thielen, Jordy; van den Broek, Philip; Farquhar, Jason; Desain, Peter

    2015-01-01

    Brain-Computer Interfaces (BCIs) allow users to control devices and communicate by using brain activity only. BCIs based on broad-band visual stimulation can outperform BCIs using other stimulation paradigms. Visual stimulation with pseudo-random bit-sequences evokes specific Broad-Band Visually Evoked Potentials (BBVEPs) that can be reliably used in BCI for high-speed communication in speller applications. In this study, we report a novel paradigm for a BBVEP-based BCI that utilizes a generative framework to predict responses to broad-band stimulation sequences. In this study we designed a BBVEP-based BCI using modulated Gold codes to mark cells in a visual speller BCI. We defined a linear generative model that decomposes full responses into overlapping single-flash responses. These single-flash responses are used to predict responses to novel stimulation sequences, which in turn serve as templates for classification. The linear generative model explains on average 50% and up to 66% of the variance of responses to both seen and unseen sequences. In an online experiment, 12 participants tested a 6 × 6 matrix speller BCI. On average, an online accuracy of 86% was reached with trial lengths of 3.21 seconds. This corresponds to an Information Transfer Rate of 48 bits per minute (approximately 9 symbols per minute). This study indicates the potential to model and predict responses to broad-band stimulation. These predicted responses are proven to be well-suited as templates for a BBVEP-based BCI, thereby enabling communication and control by brain activity only. PMID:26208328

  18. 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

  19. 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.

  20. Identification of Stimulated Sites Using Artificial Neural Networks Based on Transcranial Magnetic Stimulation-Elicited Motor Evoked Potentials and Finger Forces

    NASA Astrophysics Data System (ADS)

    Fukuda, Hiroshi; Odagaki, Masato; Hiwaki, Osamu

    Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) vary in their amplitude from trial to trial. To investigate the functions of motor cortex by TMS, it is necessary to confirm the causal relationship between stimulated sites and variable MEPs. We created artificial neural networks to classify sets of variable MEP signals and finger forces into the corresponding stimulated sites. We conducted TMS at three different positions over M1 and measured MEPs of hand and forearm muscles and forces of the index finger in four subjects. We estimated the sites within motor cortex stimulated by TMS based on cortical columnar structure and nerve excitation properties. Finally, we tried to classify the various MEPs and finger forces into three groups using artificial neural networks. MEPs and finger forces varied from trial to trial, even if the stimulating coil was fixed on the subject's head. Our proposed neural network was able to identify the MEPs and finger forces with the corresponding stimulated sites in M1. We proposed the artificial neural networks to confirm the TMS-stimulated sites using various MEPs and evoked finger forces.

  1. Histograms of the unitary evoked potential of the mouse diaphragm show multiple peaks.

    PubMed

    Kriebel, M E; Llados, F; Matteson, D R

    1982-01-01

    1. Two classes of miniature end-plate potentials (m.e.p.p.s) were recorded from diaphragm neuromuscular junctions. Amplitude histograms of both classes had multiple peaks that were integral multiples of the smallest peak (s-m.e.p.p.s). The smaller m.e.p.p.s formed the first three or four peaks of histograms and the number of m.e.p.p.s (skew-m.e.p.p.s) in each peak decreased, forming an over-all skewed distribution. The larger m.e.p.p.s (bell-m.e.p.p.s) formed a more-or-less bell-shaped distribution. The distribution of m.e.p.p.s varied from mainly skew- to mainly bell-m.e.p.p.s. In young adult mice the number of subunits composing the classical m.e.p.p.s varied between ten and fifteen at room temperature; at higher temperatures the range was from three to ten subunits.2. End-plate potentials (e.p.p.s) were reduced with cobalt ions (ca. 4 mm) until most nerve impulses failed to release transmitter. The amplitudes of ;unitary evoked potentials' were of the bell-m.e.p.p. class and histograms show integral multiple peaks that correspond to the peaks in histograms of the bell-m.e.p.p.s.3. The peaks in both m.e.p.p. and unitary e.p.p. histograms remained in the same position throughout the recording period and became more distinct as the sample size increased.4. The variance of the s-m.e.p.p. was estimated from the noise and measurement error and the variance of all peaks in the histograms. Most variance of the first peak (s-m.e.p.p.) was due to noise and measurement error.5. The integral peaks in the m.e.p.p. and ;unitary evoked potential' histograms are predicted with a probability density model based on the estimated variance of the s-m.e.p.p. and the assumption that larger potentials are composed of subunits the size of s-m.e.p.p.s. The data and model support the hypothesis that m.e.p.p.s and unitary potentials are composed of subunits.

  2. Ratio between the amplitude of sensory evoked potentials at the wrist in both hands of left-handed subjects.

    PubMed Central

    Martínez, A C; Conde, M C; Campo, F D; Mingo, P; Ferrer, M T

    1980-01-01

    Maximum sensory conduction velocity, duration and amplitude of the sensory evoked potentials at the wrist on stimulating digits 1, 2, 3 and 5, were determined bilaterally in 21 left-handed subjects with an age range from 6 to 47 years. The amplitude of the sensory evoked potential at the wrist was larger in the right hand. This asymmetry is the reverse of the one previously observed in right-handed infants and adults. It could be physiological and suggests a difference in density of sensory innervation between the two hands. Asymmetry of sensory innervation can be helpful in the study of hand dominance. PMID:7359155

  3. A Preclinical Study of Laryngeal Motor-Evoked Potentials as a Marker Vagus Nerve Activation.

    PubMed

    Grimonprez, Annelies; Raedt, Robrecht; De Taeye, Leen; Larsen, Lars Emil; Delbeke, Jean; Boon, Paul; Vonck, Kristl

    2015-12-01

    Vagus nerve stimulation (VNS) is a treatment for refractory epilepsy and depression. Previous studies using invasive recording electrodes showed that VNS induces laryngeal motor-evoked potentials (LMEPs) through the co-activation of the recurrent laryngeal nerve and subsequent contractions of the laryngeal muscles. The present study investigates the feasibility of recording LMEPs in chronically VNS-implanted rats, using a minimally-invasive technique, to assess effective current delivery to the nerve and to determine optimal VNS output currents for vagal fiber activation. Three weeks after VNS electrode implantation, signals were recorded using an electromyography (EMG) electrode in the proximity of the laryngeal muscles and a reference electrode on the skull. The VNS output current was gradually ramped up from 0.1 to 1.0 mA in 0.1 mA steps. In 13/27 rats, typical LMEPs were recorded at low VNS output currents (median 0.3 mA, IQR 0.2-0.3 mA). In 11/27 rats, significantly higher output currents were required to evoke electrophysiological responses (median 0.7 mA, IQR 0.5-0.7 mA, p < 0.001). The latencies of these responses deviated significantly from LMEPs (p < 0.05). In 3/27 rats, no electrophysiological responses to simulation were recorded. Minimally invasive LMEP recordings are feasible to assess effective current delivery to the vagus nerve. Furthermore, our results suggest that low output currents are sufficient to activate vagal fibers.

  4. 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.

  5. Effects of overt and covert attention on the steady-state visual evoked potential.

    PubMed

    Walter, Sabrina; Quigley, Cliodhna; Andersen, Søren K; Mueller, Matthias M

    2012-06-21

    Flickering stimuli evoke an oscillatory brain response with the same frequency as the driving stimulus, the so-called steady-state visual evoked potential (SSVEP). SSVEPs are robust brain signals whose amplitudes are enhanced with attention and thus play a major role in the development and use of non-invasive Brain-Computer Interfaces (BCIs). We compared the modulation of SSVEP amplitudes when subjects directly gazed at a flickering array of static dots (overt attention) to when they covertly shifted attention to the dots keeping their eyes at central fixation. A discrimination task was performed at the attended location to ensure that subjects shifted attention as instructed. Horizontal eye movements (allowed in overt attention but to be avoided in covert attention) were monitored by the horizontal electrooculogram. Subjects' behavioural performance was significantly reduced in covert attention compared to overt attention. Correspondingly, attentional modulation of SSVEP amplitudes by overt attention was larger in magnitude than for covert attention. Overt attention also changed the topographical distribution of SSVEP amplitudes on the scalp. Stimuli elicited the largest amplitudes at central occipital electrodes when they were overtly attended and at contralateral parieto-occipital sites when they were covertly attended. Accordingly, source analysis revealed clear centrally located sources in early visual areas in overt attention, regardless of the attended visual hemifield. Taken together these results affirm that overt and covert attention have qualitatively and quantitatively different effects on SSVEP responses as well as on task performance. Moreover, our results suggest that navigating SSVEP-BCIs with overt attention is more reliable and highlight some of the challenges in developing BCIs for patients who have lost the ability to move their eyes.

  6. Effect of white noise "masking" on vestibular evoked potentials recorded using different stimulus modalities.

    PubMed

    Freeman, S; Plotnik, M; Elidan, J; Rosen, L J; Sohmer, H

    1999-01-01

    Short latency vestibular evoked potentials (VsEPs) to linear acceleration impulses (L-VsEPs) are initiated in the otolith organs (saccule and utricle). Some of the saccule afferents have been reported to respond not only to linear acceleration, but also to high intensity acoustic stimuli. If so, the L-VsEP recorded from the saccule (elicited with the stimulus orientated relative to the head so as to optimally activate the saccule, i.e. stimulus in the vertical plane, Z-VsEP) should be reduced during high intensity broad band noise (BBN) "masking". Conversely, the utricular afferents have been reported to be less auditory-sensitive. Therefore, an L-VsEP which is mainly utricular in origin (stimulus in the horizontal plane, X-VsEP) should be less affected by this noise "masking". This was investigated in rats by recording X-VsEPs and Z-VsEPs and angular VsEPs (A-VsEPs), originating in the lateral semi-circular canals, before, during and after exposure to short duration, high intensity (113 dB SPL) BBN. This intensity completely masked auditory nerve evoked responses. The Z-VsEP did appear to be slightly more affected by the noise "masking" than the X-VsEP, implying the presence of more auditory-sensitive elements in the saccule. The A-VsEP was also affected by the BBN. The overall effect was relatively small (on average, 10-25% depression of the first wave of the different VsEPs). The responses showed recovery 5 min later. PMID:10380734

  7. 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…

  8. Cortisol rapidly affects amplitudes of heartbeat-evoked brain potentials--implications for the contribution of stress to an altered perception of physical sensations?

    PubMed

    Schulz, André; Strelzyk, Florian; Ferreira de Sá, Diana S; Naumann, Ewald; Vögele, Claus; Schächinger, Hartmut

    2013-11-01

    Little is known about the impact of stress and stress hormones on the processing of visceral-afferent signals. Clinical data suggest that cortisol may lower the threshold for interoceptive stimuli, while a pharmacological administration of cortisol decreases the sensitivity for physical symptoms. To clarify the role of cortisol for the processing of interoceptive signals, we investigated 16 healthy men on two occasions, once during the infusion of 4 mg of cortisol and once during the infusion of a placebo substance. Heartbeat-evoked potentials (HEP; derived from resting EEG and ECG, during open and closed eyes), which are psychophysiological indicators for the cortical processing of cardioceptive signals, were measured over 6-min periods once before, and four times after the infusion (1-7, 11-17, 21-27 and 31-37 min). We found that HEP amplitudes were higher during open than during closed eyes between 1 and 17 min after cortisol infusion. There was no effect of cortisol on heart rate. We conclude that cortisol may rapidly modulate the cortical processing of cardioceptive neural signals. These results may have relevance for the effects of stress on the development and maintenance of psychosomatic symptoms.

  9. [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

  10. 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.

  11. Cerebral monitoring in the operating room and the intensive care unit - an introductory for the clinician and a guide for the novice wanting to open a window to the brain. Part II: Sensory-evoked potentials (SSEP, AEP, VEP).

    PubMed

    Freye, Enno

    2005-04-01

    after severe head trauma and the effects of therapy. 10. An intraoperative warning device of unsuspected awareness during light anesthesia when movement is abolished by muscle relaxants and cardiovascular responses are modified by vasoactive drugs. In case of the latter the stimulus is a small electrical potential applied to the skin of the hand. Thereafter, the stimulus travels along the specific nervous pathways inducing (= generating) potential activation at various sites. The generation of potential changes at various sites along the pathway is an index for the integrity of the nerve. Thus, the evoked potential can be considered a neurophysiological response (usually of the cortex) to impulses originating from some externally stimulated sensory nerve. They provide a physiological measure of the functional integrity of the sensory nerve pathway, which can be used as a clinical diagnostic tool as well as for intraoperative monitoring. The evoked potential usually is recorded from the specific cortical area corresponding to the stimulus input. The classification of evoked potentials. Stimulating a sensory nervous pathway induces evoked potentials. If the auditory nerve is stimulated by "clicks" from headphones, it is called the auditory evoked potential (AEP). The early part of the AEP waveform (less than 10 msec) is called the Brainstem Auditory Evoked Potential (BAEP) since it reflects the passing of the impulse through the brainstem. If a nerve on the arm or the leg is stimulated by a small electrical current applied to the overlying skin, it is called the Somatosensory Evoked Potential (SSEP). If, however, the retina is stimulated by means of flicker light or a sudden change in a checkerboard pattern, the evoked potential thus recorded over the corresponding cortical area is called the Visual Evoked Potential (VEP). Evoked potentials are used both as a diagnostic tool and as a monitoring technique. As diagnostic tests, evoked potentials are useful to evaluate

  12. Cerebral monitoring in the operating room and the intensive care unit - an introductory for the clinician and a guide for the novice wanting to open a window to the brain. Part II: Sensory-evoked potentials (SSEP, AEP, VEP).

    PubMed

    Freye, Enno

    2005-04-01

    after severe head trauma and the effects of therapy. 10. An intraoperative warning device of unsuspected awareness during light anesthesia when movement is abolished by muscle relaxants and cardiovascular responses are modified by vasoactive drugs. In case of the latter the stimulus is a small electrical potential applied to the skin of the hand. Thereafter, the stimulus travels along the specific nervous pathways inducing (= generating) potential activation at various sites. The generation of potential changes at various sites along the pathway is an index for the integrity of the nerve. Thus, the evoked potential can be considered a neurophysiological response (usually of the cortex) to impulses originating from some externally stimulated sensory nerve. They provide a physiological measure of the functional integrity of the sensory nerve pathway, which can be used as a clinical diagnostic tool as well as for intraoperative monitoring. The evoked potential usually is recorded from the specific cortical area corresponding to the stimulus input. The classification of evoked potentials. Stimulating a sensory nervous pathway induces evoked potentials. If the auditory nerve is stimulated by "clicks" from headphones, it is called the auditory evoked potential (AEP). The early part of the AEP waveform (less than 10 msec) is called the Brainstem Auditory Evoked Potential (BAEP) since it reflects the passing of the impulse through the brainstem. If a nerve on the arm or the leg is stimulated by a small electrical current applied to the overlying skin, it is called the Somatosensory Evoked Potential (SSEP). If, however, the retina is stimulated by means of flicker light or a sudden change in a checkerboard pattern, the evoked potential thus recorded over the corresponding cortical area is called the Visual Evoked Potential (VEP). Evoked potentials are used both as a diagnostic tool and as a monitoring technique. As diagnostic tests, evoked potentials are useful to evaluate

  13. 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

  14. 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

  15. Training voluntary motor suppression with real-time feedback of motor evoked potentials

    PubMed Central

    Majid, D. S. Adnan; Lewis, Christina

    2015-01-01

    Training people to suppress motor representations voluntarily could improve response control. We evaluated a novel training procedure of real-time feedback of motor evoked potentials (MEPs) generated by transcranial magnetic stimulation (TMS) over motor cortex. On each trial, a cue instructed participants to use a mental strategy to suppress a particular finger representation without overt movement. A single pulse of TMS was delivered over motor cortex, and an MEP-derived measure of hand motor excitability was delivered visually to the participant within 500 ms. In experiment 1, we showed that participants learned to reduce the excitability of a particular finger beneath baseline (selective motor suppression) within 30 min of practice. In experiment 2, we performed a double-blind study with 2 training groups (1 with veridical feedback and 1 with matched sham feedback) to show that selective motor suppression depends on the veridical feedback itself. Experiment 3 further demonstrated the importance of veridical feedback by showing that selective motor suppression did not arise from mere mental imagery, even when incentivized with reward. Thus participants can use real-time feedback of TMS-induced MEPs to discover an effective mental strategy for selective motor suppression. This high-temporal-resolution, trial-by-trial-feedback training method could be used to help people better control response tendencies and may serve as a potential therapy for motor disorders such as Tourette's and dystonia. PMID:25744889

  16. 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

  17. 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

  18. Training voluntary motor suppression with real-time feedback of motor evoked potentials.

    PubMed

    Majid, D S Adnan; Lewis, Christina; Aron, Adam R

    2015-05-01

    Training people to suppress motor representations voluntarily could improve response control. We evaluated a novel training procedure of real-time feedback of motor evoked potentials (MEPs) generated by transcranial magnetic stimulation (TMS) over motor cortex. On each trial, a cue instructed participants to use a mental strategy to suppress a particular finger representation without overt movement. A single pulse of TMS was delivered over motor cortex, and an MEP-derived measure of hand motor excitability was delivered visually to the participant within 500 ms. In experiment 1, we showed that participants learned to reduce the excitability of a particular finger beneath baseline (selective motor suppression) within 30 min of practice. In experiment 2, we performed a double-blind study with 2 training groups (1 with veridical feedback and 1 with matched sham feedback) to show that selective motor suppression depends on the veridical feedback itself. Experiment 3 further demonstrated the importance of veridical feedback by showing that selective motor suppression did not arise from mere mental imagery, even when incentivized with reward. Thus participants can use real-time feedback of TMS-induced MEPs to discover an effective mental strategy for selective motor suppression. This high-temporal-resolution, trial-by-trial-feedback training method could be used to help people better control response tendencies and may serve as a potential therapy for motor disorders such as Tourette's and dystonia.

  19. Normative data for the segmental acquisition of contact heat evoked potentials in cervical dermatomes

    PubMed Central

    Jutzeler, Catherine R.; Rosner, Jan; Rinert, Janosch; Kramer, John L. K.; Curt, Armin

    2016-01-01

    Contact heat evoked potentials (CHEPs) represent a neurophysiological approach to assess conduction in the spinothalamic tract. The aim of this study was to establish normative values of CHEPs acquired from cervical dermatomes (C4, C6, C8) and examine the potential confounds of age, sex, and height. 101 (49 male) healthy subjects of three different age groups (18–40, 41–60, and 61–80 years) were recruited. Normal (NB, 35–52 °C) followed by increased (IB, 42–52 °C) baseline stimulation protocols were employed to record CHEPs. Multi-variate linear models were used to investigate the effect of age, sex, and height on the CHEPs parameters (i.e., N2 latency, N2P2 amplitude, rating of perceived intensity). Compared to NB, IB stimulation reduced latency jitter within subjects, yielding larger N2P2 amplitudes, and decreased inter-subject N2 latency variability. Age was associated with reduced N2P2 amplitude and prolonged N2 latency. After controlling for height, male subjects had significantly longer N2 latencies than females during IB stimulation. The study provides normative CHEPs data in a large cohort of healthy subjects from segmentally examined cervical dermatomes. Age and sex were identified as important factors contributing to N2 latency and N2P2 amplitude. The normative data will improve the diagnosis of spinal cord pathologies. PMID:27708413

  20. Evaluating the noise in electrically evoked compound action potential measurements in cochlear implants.

    PubMed

    Undurraga, Jaime A; Carlyon, Robert P; Wouters, Jan; van Wieringen, Astrid

    2012-07-01

    Electrically evoked compound action potentials (ECAPs) are widely used to study the excitability of the auditory nerve and stimulation properties in cochlear implant (CI) users. However, ECAP detection can be difficult and very subjective at near-threshold stimulation levels or in spread of excitation measurements. In this study, we evaluated the statistical properties of the background noise (BN) and the postaverage residual noise (RN) in ECAP measurements in order to determine an objective detection criterion. For the estimation of the BN and the RN, a method currently used in auditory brainstem response measurements was applied. The potential benefit of using weighted (Bayesian) averages was also examined. All estimations were performed with a set of approximately 360 ECAP measurements recorded from five human CI users of the CII or HiRes90K device (advanced bionics). Results demonstrated that the BN was normally distributed and the RN decreased according to the square root of the number of averages. No additional benefit was observed by using weighted averaging. The noise was not significantly different either at different stimulation intensities or across recording electrodes along the cochlea. The analysis of the statistical properties of the noise indicated that a signal-to-noise ratio of 1.7 dB as a detection criterion corresponds to a false positive detection rate of 1% with the used measurement setup.

  1. 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

  2. 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…

  3. Influence of the midbrain reticular formation irradiation with luminescent incoherent light on evoked potential of cerebral cortex in cats

    NASA Astrophysics Data System (ADS)

    Malinovskaya, Svetlana L.; Abakarov, Asadulla; Monich, Victor A.

    1996-11-01

    In acute experiments on cats it is shown, that direct, of- low-intensity incoherent light exposure on midbrain reticular formation, cases brain cortex projection areas functional state changes, which find expression in shifting amplitude of both positive and negative components of cortex evoked potentials on visual stimuli.

  4. 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...

  5. Click-evoked potentials in a large marine mammal, the adult male northern elephant seal (Mirounga angustirostris).

    PubMed

    Houser, Dorian S; Crocker, Daniel E; Finneran, James J

    2008-07-01

    Auditory evoked potential (AEP) hearing studies in marine mammals should consider an expected size-dependent reduction in AEP amplitude. This study is the first to measure the click-evoked response in a large marine mammal, the adult male elephant seal (Mirounga angustirostris). Click stimuli were presented at peak-peak equivalent sound pressure levels of 117-118 dB re: 20 microPa. Three positive peaks (P1-P3) and two negative peaks (N4 and N5) were observed in the AEP. Response latencies were longer than previously observed in a 1.8 yr old seal and the maximum peak-peak amplitude was comparatively reduced by more than 60%. The inverse relationship between size and AEP amplitude will likely require increased averaging with larger subjects and possibly modifications to electrode placement and design in order to increase the quality of recorded evoked responses.

  6. 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.

  7. Membrane potential dynamics of populations of cortical neurons during auditory streaming.

    PubMed

    Farley, Brandon J; Noreña, Arnaud J

    2015-10-01

    How a mixture of acoustic sources is perceptually organized into discrete auditory objects remains unclear. One current hypothesis postulates that perceptual segregation of different sources is related to the spatiotemporal separation of cortical responses induced by each acoustic source or stream. In the present study, the dynamics of subthreshold membrane potential activity were measured across the entire tonotopic axis of the rodent primary auditory cortex during the auditory streaming paradigm using voltage-sensitive dye imaging. Consistent with the proposed hypothesis, we observed enhanced spatiotemporal segregation of cortical responses to alternating tone sequences as their frequency separation or presentation rate was increased, both manipulations known to promote stream segregation. However, across most streaming paradigm conditions tested, a substantial cortical region maintaining a response to both tones coexisted with more peripheral cortical regions responding more selectively to one of them. We propose that these coexisting subthreshold representation types could provide neural substrates to support the flexible switching between the integrated and segregated streaming percepts.

  8. Changes in somatosensory-evoked potentials and high-frequency oscillations after paired-associative stimulation.

    PubMed

    Murakami, Takenobu; Sakuma, Kenji; Nomura, Takashi; Uemura, Yusuke; Hashimoto, Isao; Nakashima, Kenji

    2008-01-01

    Paired-associative stimulation (PAS), combining electrical median nerve stimulation with transcranial magnetic stimulation (TMS) with a variable delay, causes long-term potentiation or depression (LTP/LTD)-like cortical plasticity. In the present study, we examined how PAS over the motor cortex affected a distant site, the somatosensory cortex. Furthermore, the influences of PAS on high-frequency oscillations (HFOs) were investigated to clarify the origin of HFOs. Interstimulus intervals between median nerve stimulation and TMS were 25 ms (PAS(25)) and 10 ms (PAS(10)). PAS was performed over the motor and somatosensory cortices. SEPs following median nerve stimulation were recorded before and after PAS. HFOs were isolated by 400-800 Hz band-pass filtering. PAS(25) over the motor cortex increased the N20-P25 and P25-N33 amplitudes and the HFOs significantly. The enhancement of the P25-N33 amplitude and the late HFOs lasted more than 60 min. After PAS(10) over the motor cortex, the N20-P25 and P25-N33 amplitudes decreased for 40 min, and the HFOs decreased for 60 min. Frontal SEPs were not affected after PAS over the motor cortex. PAS(25/10) over the somatosensory cortex did not affect SEPs and HFOs. PAS(25/10) over the motor cortex caused the LTP/LTD-like phenomena in a distant site, the somatosensory cortex. The PAS paradigms over the motor cortex can modify both the neural generators of SEPs and HFOs. HFOs may reflect the activation of GABAergic inhibitory interneurons regulating pyramidal neurons in the somatosensory cortex. PMID:17724581

  9. Motor evoked potentials in standing and recumbent calves induced by magnetic stimulation at the foramen magnum.

    PubMed

    Rijckaert, J; Pardon, B; Verryken, K; Van Ham, L; van Loon, G; Deprez, P

    2016-10-01

    The aims of this study were to determine reference values for magnetic motor evoked potentials (mMEPs) in calves and the influence of position during examination (standing or lateral recumbency). Reference values were determined using 41 healthy Holstein Friesian bull calves aged 1-10 months; standing and lateral recumbency were examined in 11 calves. Maximal magnetic stimulation was performed at the level of the foramen magnum with a magnetic field of 4 T at the coil surface. In standing position, distinct, reproducible mMEPs were obtained in all calves. Onset latency (LAT) (mean ± standard deviation) was significantly shorter in the thoracic limbs (34.4 ± 3.1 ms) than in the pelvic limbs (44.6 ± 3.0 ms). Amplitude (AMPL) was significantly higher in the thoracic limbs (3.7 ± 1.7 mV) than in the pelvic limbs (3.3 ± 1.7 mV) and significantly increased with body length. Age, body weight, height at the withers and rectal temperature had no significant association with LAT or AMPL, and no differences between left and right were noted. In the lateral position, only 64% of the calves showed responses in the four limbs; in these calves, LAT (29.7 ± 4.7 ms) and AMPL (3.0 ± 1.8 mV) in the thoracic limbs were significantly different from AMPL (47.0 ± 7.4 ms) and LAT (2.1 ± 2.1 mV) in the pelvic limbs. In conclusion, mMEPs in limb muscles can be evoked in calves by stimulation at the level of the foramen magnum. mMEPs are more difficult to obtain in lateral recumbency than in standing calves.

  10. Motor evoked potentials in standing and recumbent calves induced by magnetic stimulation at the foramen magnum.

    PubMed

    Rijckaert, J; Pardon, B; Verryken, K; Van Ham, L; van Loon, G; Deprez, P

    2016-10-01

    The aims of this study were to determine reference values for magnetic motor evoked potentials (mMEPs) in calves and the influence of position during examination (standing or lateral recumbency). Reference values were determined using 41 healthy Holstein Friesian bull calves aged 1-10 months; standing and lateral recumbency were examined in 11 calves. Maximal magnetic stimulation was performed at the level of the foramen magnum with a magnetic field of 4 T at the coil surface. In standing position, distinct, reproducible mMEPs were obtained in all calves. Onset latency (LAT) (mean ± standard deviation) was significantly shorter in the thoracic limbs (34.4 ± 3.1 ms) than in the pelvic limbs (44.6 ± 3.0 ms). Amplitude (AMPL) was significantly higher in the thoracic limbs (3.7 ± 1.7 mV) than in the pelvic limbs (3.3 ± 1.7 mV) and significantly increased with body length. Age, body weight, height at the withers and rectal temperature had no significant association with LAT or AMPL, and no differences between left and right were noted. In the lateral position, only 64% of the calves showed responses in the four limbs; in these calves, LAT (29.7 ± 4.7 ms) and AMPL (3.0 ± 1.8 mV) in the thoracic limbs were significantly different from AMPL (47.0 ± 7.4 ms) and LAT (2.1 ± 2.1 mV) in the pelvic limbs. In conclusion, mMEPs in limb muscles can be evoked in calves by stimulation at the level of the foramen magnum. mMEPs are more difficult to obtain in lateral recumbency than in standing calves. PMID:27687949

  11. 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

  12. Continuous- and Discrete-Time Stimulus Sequences for High Stimulus Rate Paradigm in Evoked Potential Studies

    PubMed Central

    Wang, Tao; Huang, Jiang-hua; Lin, Lin

    2013-01-01

    To obtain reliable transient auditory evoked potentials (AEPs) from EEGs recorded using high stimulus rate (HSR) paradigm, it is critical to design the stimulus sequences of appropriate frequency properties. Traditionally, the individual stimulus events in a stimulus sequence occur only at discrete time points dependent on the sampling frequency of the recording system and the duration of stimulus sequence. This dependency likely causes the implementation of suboptimal stimulus sequences, sacrificing the reliability of resulting AEPs. In this paper, we explicate the use of continuous-time stimulus sequence for HSR paradigm, which is independent of the discrete electroencephalogram (EEG) recording system. We employ simulation studies to examine the applicability of the continuous-time stimulus sequences and the impacts of sampling frequency on AEPs in traditional studies using discrete-time design. Results from these studies show that the continuous-time sequences can offer better frequency properties and improve the reliability of recovered AEPs. Furthermore, we find that the errors in the recovered AEPs depend critically on the sampling frequencies of experimental systems, and their relationship can be fitted using a reciprocal function. As such, our study contributes to the literature by demonstrating the applicability and advantages of continuous-time stimulus sequences for HSR paradigm and by revealing the relationship between the reliability of AEPs and sampling frequencies of the experimental systems when discrete-time stimulus sequences are used in traditional manner for the HSR paradigm. PMID:23606900

  13. 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

  14. The brain computer interface using flash visual evoked potential and independent component analysis.

    PubMed

    Lee, Po-Lei; Hsieh, Jen-Chuen; Wu, Chi-Hsun; Shyu, Kuo-Kai; Chen, Shyan-Shiou; Yeh, Tzu-Chen; Wu, Yu-Te

    2006-10-01

    In this study flashing stimuli, such as digits or letters, are displayed on a LCD screen to induce flash visual evoked potentials (FVEPs). The aim of the proposed interface is to generate desired strings while one stares at target stimulus one after one. To effectively extract visually-induced neural activities with superior signal-to-noise ratio, independent component analysis (ICA) is employed to decompose the measured EEG and task-related components are subsequently selected for data reconstruction. In addition, all the flickering sequences are designed to be mutually independent in order to remove the contamination induced by surrounding non-target stimuli from the ICA-recovered signals. Since FVEPs are time-locked and phase-locked to flash onsets of gazed stimulus, segmented epochs from ICA-recovered signals based on flash onsets of gazed stimulus will be sharpen after averaging whereas those based on flash onsets of non-gazed stimuli will be suppressed after averaging. The stimulus inducing the largest averaged FVEPs is identified as the gazed target and corresponding digit or letter is sent out. Five subjects were asked to gaze at each stimulus. The mean detection accuracy resulted from averaging 15 epochs was 99.7%. Another experiment was to generate a specified string '0287513694E'. The mean accuracy and information transfer rates were 83% and 23.06 bits/min, respectively.

  15. 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.

  16. 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

  17. Flumazenil antagonizes the suppressive effect of midazolam on the somatosensory evoked potentials in the rat.

    PubMed Central

    Suzuki, N.; Hirose, Y.; Katakura, N.; Kubota, Y.

    1991-01-01

    The effect of flumazenil, a specific benzodiazepine antagonist, on the midazolam-induced suppression of somatosensory evoked potentials (SEPs) following strong electrical stimulation of the upper lip was investigated in Wistar albino rats. The averaged SEPs were recorded from the contralateral surface of the skull in the temporal area. Each rat received midazolam in a dose of 10 mg/kg intraperitoneally. Five min after midazolam injection, the relative amplitude of the P1N1 wave of the SEPs was reduced significantly. A 0.5 mg dose of flumazenil or physiological saline was injected intraperitoneally 7.5 min after midazolam injection. The P1N1 amplitude recovered rapidly to the control value in the flumazenil group but not in the physiological saline group. No significant differences were found in the latencies of the P1 and N1 peaks before or after midazolam or flumazenil injection. It is suggested that flumazenil strongly antagonizes the midazolam-induced suppression of SEPs in the rat. PMID:1809048

  18. Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials

    PubMed Central

    Calderón-Garcidueñas, Lilian; D’Angiulli, Amedeo; Kulesza, Randy J; Torres-Jardón, Ricardo; Osnaya, Norma; Romero, Lina; Keefe, Sheyla; Herritt, Lou; Brooks, Diane M; Avila-Ramirez, Jose; Delgado-Chávez, Ricardo; Medina-Cortina, Humberto; González-González, Luis Oscar

    2011-01-01

    We assessed brainstem inflammation in children exposed to air pollutants by comparing brainstem auditory evoked potentials (BAEPs) and blood inflammatory markers in children age 96.3± 8.5 months from highly polluted (n=34) versus a low polluted city (n=17). The brainstems of nine children with accidental deaths were also examined. Children from the highly polluted environment had significant delays in wave III (t(50)=17.038; p<0.0001) and wave V (t(50)=19.730; p<0.0001) but no delay in wave I (p=0.548). They also had significantly longer latencies than controls for interwave intervals I–III, III–V, and I–V (all t(50)> 7.501; p<0.0001), consisting with delayed central conduction time of brainstem neural transmission. Highly exposed children showed significant evidence of inflammatory markers and their auditory and vestibular nuclei accumulated α synuclein and/or β amyloid 1–42. Medial superior olive neurons, critically involved in BAEPs, displayed significant pathology. Children’s exposure to urban air pollution increases their risk for auditory and vestibular impairment. PMID:21458557

  19. 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.

  20. Instrumentation to record evoked potentials for closed-loop control of deep brain stimulation.

    PubMed

    Kent, Alexander R; Grill, Warren M

    2011-01-01

    Closed-loop deep brain stimulation (DBS) systems offer promise in relieving the clinical burden of stimulus parameter selection and improving treatment outcomes. In such a system, a feedback signal is used to adjust automatically stimulation parameters and optimize the efficacy of stimulation. We explored the feasibility of recording electrically evoked compound action potentials (ECAPs) during DBS for use as a feedback control signal. A novel instrumentation system was developed to suppress the stimulus artifact and amplify the small magnitude, short latency ECAP response during DBS with clinically relevant parameters. In vitro testing demonstrated the capabilities to increase the gain by a factor of 1,000× over a conventional amplifier without saturation, reduce distortion of mock ECAP signals, and make high fidelity recordings of mock ECAPs at latencies of only 0.5 ms following DBS pulses of 50 to 100 μs duration. Subsequently, the instrumentation was used to make in vivo recordings of ECAPs during thalamic DBS in cats, without contamination by the stimulus artifact. The signal characteristics were similar across three experiments, suggesting common neural activation patterns. The ECAP recordings enabled with this novel instrumentation may provide insight into the type and spatial extent of neural elements activated during DBS, and could serve as feedback control signals for closed-loop systems. PMID:22255894

  1. [A significant increase in intraoperative flash visual evoked potential amplitude during craniopharyngioma surgery-case report].

    PubMed

    Kawaguchi, Tomohiro; Ogawa, Yoshikazu; Fujiwara, Satoru; Tominaga, Teiji

    2015-04-01

    The flash visual evoked potential (VEP) is a useful diagnostic modality for visual preservation during surgery. Decreased VEP amplitude is recognized to indicate visual deterioration;however, whether intraoperative VEP can detect visual improvement remains unclear. We describe a craniopharyngioma case with a significant increase in VEP amplitude during surgery. A 67-year-old woman presented with progressive gait disturbance and impaired consciousness. Head magnetic resonance imaging demonstrated a sellar-suprasellar tumor compressing the optic chiasm upward with significant ventricular dilation. Her Glasgow Coma Scale was E3V3M5. Visual fields and acuity could not be examined because of impaired consciousness, and she could not see/recognize objects on a table. Preoperative VEP showed reproducible waveforms. Tumor removal by the extended transsphenoidal approach was performed with VEP monitoring. Increased VEP amplitude was observed after dural incision and persisted until the surgery ended. Postoperative VEP waveforms were also reproducible, but visual fields/acuity could not be examined because of cognitive dysfunction. Useful visual function was restored, and she became independent in daily life. The histological diagnosis was craniopharyngioma. The patient underwent ventriculo-peritoneal shunting for hydrocephalus 16 days after tumor removal. The postoperative course was uneventful and she was transferred to another hospital for rehabilitation. Intraoperative VEP may indicate visual improvement during surgery, which is a useful objective assessment for visual function in patients with impaired consciousness and cognitive dysfunction.

  2. Visual evoked potentials for intraoperative neurophysiologic monitoring using total intravenous anesthesia.

    PubMed

    Wiedemayer, Helmut; Fauser, Barbara; Armbruster, W; Gasser, Thomas; Stolke, Dietmar

    2003-01-01

    Conflicting reports on the usefulness of intraoperative monitoring of visual function by means of visual evoked potentials (VEPs) initiated this study. In 32 patients without visual problems, VEPs were recorded to evaluate the reliability for intraoperative monitoring with total intravenous anesthesia. All patients underwent noncranial surgery. Using a standard technique, VEPs were recorded preoperatively in the awake patients and after induction of anesthesia during surgery. A total of 1436 intraoperative traces were recorded and analyzed. A minor prolongation of the P100 latency of 8% and a more pronounced attenuation of the P100-N145 amplitude of 60% were observed in the anesthetized patients. In most of the anesthetized patients, a stable recording of VEPs was not obtainable. In 4 patients (12.5%), clearly identifiable VEP peaks were detected in more than 90% of the traces recorded intraoperatively. In 88% of the patients, reproducible VEPs were obtained in less than 75% of the intraoperative traces only. We concluded that with standard recording techniques and total intravenous anesthesia, intraoperative VEP monitoring in surgically anesthetized patients is not reliable.

  3. Analysis of the visual evoked potential in anesthesia with sevoflurane and chloral hydrate

    PubMed Central

    Ghita, AM; Parvu, D; Sava, R; Georgescu, L; Zagrean, L

    2013-01-01

    The visually evoked potential (VEP) is an electrical signal generated by the occipital cortex in response to light stimulation of the retina. The clinical importance of the VEP consists in the diagnosis of optic nerve diseases and others ocular diseases. For experimental studies of VEP in experimental animals anesthesia is frequently required. Our study sought VEP changes depending on the type and depth of anesthesia. Methods: this study evaluated VEPs in 20 Wistar rats under two anesthetics. Ten rats were anesthetized with sevoflurane and ten rats with chloral hydrate. Results: The amplitudes, latencies and morphology of the VEP varied with the depth of anesthesia. The latency of VEP increases with the depth of anesthesia and the amplitude of the waves becomes more positive once the anesthesia decreases under sevoflurane and more negative under chloral hydrate. The variability of VEP was different under the two anesthetics with greater peak latencies under sevoflurane than under chloral hydrate at the same depth of anesthesia. In conclusion: it is important to know the influence of the anesthetic and the depth of anesthesia over VEPS, because they may constitute a confounding factor in studying VEP in different diseases of optic nerve or eyeball. PMID:23904886

  4. Auditory evoked potentials (AEP) methods for population-level assessment of hearing sensitivity in bottlenose dolphins

    NASA Astrophysics Data System (ADS)

    Houser, Dorian; Finneran, James

    2005-04-01

    A portable system for recording auditory evoked potentials (AEP) was developed to rapidly assess the hearing sensitivity of dolphins in air. The system utilizes a transducer embedded in a silicone suction cup to deliver amplitude modulated tones to the dolphin through the lower jaw. Frequencies tested range from 10-150 kHz and testing of both ears is completed within 90 min. AEP-determined thresholds from one subject were benchmarked against that subject's direct field behavioral audiogram to quantify variation between the two methods. To date, AEP audiograms have been obtained from over 30 bottlenose dolphins. Considerable individual variation in frequency-specific hearing sensitivity was observed. Some high-frequency hearing loss was observed in relatively young (early 20s) and old (35+ years) animals; conversely, age was not necessarily related to hearing loss as several animals greater than 40 years of age had good hearing sensitivity across the range of tested frequencies. Profound hearing loss typically occurred at higher frequencies. Decline in sensitivity was rapid in all cases and began between 50-60 kHz. Increased sample size of hearing sensitivity in dolphins suggest that the use of audiometric functions from single animals as representative of population level audiometry might be misleading.

  5. Saccular function in otosclerosis patients: bone conducted-vestibular evoked myogenic potential analysis.

    PubMed

    Amali, Amin; Mahdi, Parvane; Karimi Yazdi, Alireza; Khorsandi Ashtiyani, Mohammad Taghi; Yazdani, Nasrin; Vakili, Varasteh; Pourbakht, Akram

    2014-01-01

    Vestibular involvements have long been observed in otosclerotic patients. Among vestibular structures saccule has the closest anatomical proximity to the sclerotic foci, so it is the most prone vestibular structure to be affected during the otosclerosis process. The aim of this study was to investigate the saccular function in patients suffering from otosclerosis, by means of Vestibular Evoked Myogenic Potential (VEMP). The material consisted of 30 otosclerosis patients and 20 control subjects. All participants underwent audiometric and VEMP testing. Analysis of tests results revealed that the mean values of Air-Conducted Pure Tone Average (AC-PTA) and Bone-Conducted Pure Tone Average (BC-PTA) in patients were 45.28 ± 15.57 and 19.68 ± 10.91, respectively and calculated 4 frequencies Air Bone Gap (ABG) was 25.64 ± 9.95. The VEMP response was absent in 14 (28.57%) otosclerotic ears. A statistically significant increase in latency of the p13 was found in the affected ears (P=0.004), differences in n23 latency did not reach a statistically significant level (P=0.112). Disparities in amplitude of p13-n23 in between two study groups was statistically meaningful (P=0.009), indicating that the patients with otosclerosis had lower amplitudes. This study tends to suggest that due to the direct biotoxic effect of the materials released from the otosclerosis foci on saccular receptors, there might be a possibility of vestibular dysfunction in otosclerotic patients. PMID:24659067

  6. Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials.

    PubMed

    Calderón-Garcidueñas, Lilian; D'Angiulli, Amedeo; Kulesza, Randy J; Torres-Jardón, Ricardo; Osnaya, Norma; Romero, Lina; Keefe, Sheyla; Herritt, Lou; Brooks, Diane M; Avila-Ramirez, Jose; Delgado-Chávez, Ricardo; Medina-Cortina, Humberto; González-González, Luis Oscar

    2011-06-01

    We assessed brainstem inflammation in children exposed to air pollutants by comparing brainstem auditory evoked potentials (BAEPs) and blood inflammatory markers in children age 96.3±8.5 months from highly polluted (n=34) versus a low polluted city (n=17). The brainstems of nine children with accidental deaths were also examined. Children from the highly polluted environment had significant delays in wave III (t(50)=17.038; p<0.0001) and wave V (t(50)=19.730; p<0.0001) but no delay in wave I (p=0.548). They also had significantly longer latencies than controls for interwave intervals I-III, III-V, and I-V (all t(50)>7.501; p<0.0001), consisting with delayed central conduction time of brainstem neural transmission. Highly exposed children showed significant evidence of inflammatory markers and their auditory and vestibular nuclei accumulated α synuclein and/or β amyloid(1-42). Medial superior olive neurons, critically involved in BAEPs, displayed significant pathology. Children's exposure to urban air pollution increases their risk for auditory and vestibular impairment. PMID:21458557

  7. A Case of Functional (Psychogenic) Monocular Hemianopia Analyzed by Measurement of Hemifield Visual Evoked Potentials

    PubMed Central

    Yoneda, Tsuyoshi; Fukuda, Ken; Nishimura, Mayu; Fukushima, Atsuki

    2013-01-01

    Purpose Functional monocular hemianopia is an extremely rare condition, for which measurement of hemifield visual evoked potentials (VEPs) has not been previously described. Methods A 14-year-old boy with functional monocular hemianopia was followed up with Goldmann perimetry and measurement of hemifield and full-field VEPs. Results The patient had a history of monocular temporal hemianopia of the right eye following headache, nausea and ague. There was no relative afferent pupillary defect, and a color perception test was normal. Goldmann perimetry revealed a vertical monocular temporal hemianopia of the right eye; the hemianopia on the right was also detected with a binocular visual field test. Computed tomography, magnetic resonance imaging (MRI) and MR angiography of the brain including the optic chiasm as well as orbital MRI revealed no abnormalities. On the basis of these results, we diagnosed the patient's condition as functional monocular hemianopia. Pattern VEPs according to the International Society for Clinical Electrophysiology of Vision (ISCEV) standard were within the normal range. The hemifield pattern VEPs for the right eye showed a symmetrical latency and amplitude for nasal and temporal hemifield stimulation. One month later, the visual field defect of the patient spontaneously disappeared. Conclusions The latency and amplitude of hemifield VEPs for a patient with functional monocular hemianopia were normal. Measurement of hemifield VEPs may thus provide an objective tool for distinguishing functional hemianopia from hemifield loss caused by an organic lesion. PMID:24474929

  8. Development and evaluation of the piecewise Prony method for evoked potential analysis.

    PubMed

    Garoosi, V; Jansen, B H

    2000-12-01

    A new method is presented to decompose nonstationary signals into a summation of oscillatory components with time varying frequency, amplitude, and phase characteristics. This method, referred to as piecewise Prony method (PPM), is an improvement over the classical Prony method, which can only deal with signals containing components with fixed frequency, amplitude and phase, and monotonically increasing or decreasing rate of change. PPM allows the study of the temporal profile of post-stimulus signal changes in single-trial evoked potentials (EPs), which can lead to new insights in EP generation. We have evaluated this method on simulated data to test its limitations and capabilities, and also on single-trial EPs. The simulation experiments showed that the PPM can detect amplitude changes as small as 10%, rate changes as small as 10%, and 0.15 Hz of frequency changes. The capabilities of the PPM were demonstrated using single electroencephalogram/EP trials of flash visual EPs recorded from one normal subject. The trial-by-trial results confirmed that the stimulation drastically attenuates the alpha activity shortly after stimulus presentation, with the alpha activity returning about 0.5 s later. The PPM results also provided evidence that delta activity undergoes phase alignment following stimulus presentation.

  9. [Evoked potentials and vigilance states induced during the course of choice reaction time tests].

    PubMed

    Banquet, J P; Bourzeix, J C; Lesèvre, N

    1979-01-01

    Characteristics of Visual Evoked Potentials (N120, P200, P300) were investigated during choice reaction time situations in a group of 10 subjects practising meditation (E.S.) versus a matched control group (C.S.) During a series of visual stimuli occuring at fixed intervals, with 10% random omissions, the subjects were asked : 1) to respond by a finger displacement to each visual stimulus; 2) to hold on the response to the stimulus and to respond to omission. Both tasks were recorded before and after the practice of meditation or rest for the controls. The intergroup comparison showed that the experimental subjects had faster RT's with less mistakes, and N120 and P200 of larger amplitude and shorter latency. These differencies were significant before and after meditation. The transient effects of meditation or rest, were opposite for the two groups : whereas after meditation the RT's became longer with less mistakes, and the amplitude of P300 larger, after rest there was a decrease of the P300 amplitude and no change in the RT's of the controls. These results are interpreted in terms of selective attention capacity and information processing strategies, A.S.C. being used as a model for the study of these processes.

  10. Alterations in auditory middle latency evoked potentials during meditation on a meaningful symbol--"Om".

    PubMed

    Telles, S; Nagarathna, R; Nagendra, H R; Desiraju, T

    1994-05-01

    Middle latency auditory evoked potentials were recorded in 18 male volunteers with ages between 25 and 45 years, 9 of whom had more than 10 years of experience in "Om" meditation (senior subjects), whereas the other 9 had no meditation experience (naive subjects). Both groups were studied in two types of sessions. (1) Before, during, and after 20 minutes of mentally repeating "one" (control session), and (2) a similar session, though with 20 minutes of mentally chanting "Om" (meditation session). The senior subjects showed a statistically significant (paired t-test) increase in the peak amplitude of Na wave (the maximum negative peak between 14 and 18 ms) during meditation, while the same subjects showed a statistically significant reduction in the Na wave peak amplitude during control sessions. In contrast, the naive subjects had a significant decrease in the Na wave peak amplitude during meditation sessions and a nonsignificant trend of reduction during control sessions, as well. This difference between senior and naive subjects was significant (two-way ANOVA). There were no significant changes in short latency wave V or Pa wave (the positive peak between the Na wave and 35 ms). The changes in the Na wave suggest that both mediation on a meaningful symbol, and mental repetition of a neutral word cause neural changes at the same level (possibly diencephalic). However, the change could be in opposite directions, and this difference could be correlated with differences in the duration of experience in meditation between senior and naive subjects.

  11. Rhythmic context influences the auditory evoked potentials of musicians and non-musicians.

    PubMed

    Jongsma, Marijtje L A; Desain, Peter; Honing, Henkjan

    2004-04-01

    In this study, we investigated how rhythms are processed in the brain by measuring both behaviourally obtained ratings and auditory evoked potentials (AEPs) from the EEG. We presented probe beats on seven positions within a test bar. Two bars of either a duple- or triple meter rhythm preceded probe beats. We hypothesised that sequential processing would lead to meter effects at the 1/3 and 1/2bar positions, whereas hierarchical processing would lead to context effects on the 1/3, 1/2 and 2/3bar positions. We found that metric contexts affected behavioural ratings. This effect was more pronounced for rhythmic experts. In addition, both the AEP P3a and P3b component could be identified. Though metric context affected the P3a amplitudes, group effects were less clear. We found that the AEP P3a component is sensitive to violation of temporal expectancies. In addition, behavioural data and P3a correlation coefficients (CCs) suggest that temporal patterns are processed sequentially in nonmusicians but are processed in a hierarchical way in rhythmic experts.

  12. Forward-masking based gain control in odontocete biosonar: an evoked-potential study.

    PubMed

    Supin, Alexander Ya; Nachtigall, Paul E; Breese, Marlee

    2009-04-01

    Auditory evoked potentials (AEPs) were recorded during echolocation in a false killer whale Pseudorca crassidens. An electronically synthesized and played-back ("phantom") echo was used. Each electronic echo was triggered by an emitted biosonar pulse. The echo had a spectrum similar to that of the emitted biosonar clicks, and its intensity was proportional to that of the emitted click. The attenuation of the echo relative to the emitted click and its delay was controlled by the experimenter. Four combinations of echo attenuation and delay were tested (-31 dB, 2 ms), (-40 dB, 4 ms), (-49 dB, 8 ms), and (-58 dB, 16 ms); thus, attenuation and delay were associated with a rate of 9 dB of increased attenuation per delay doubling. AEPs related to emitted clicks displayed a regular amplitude dependence on the click level. Echo-related AEPs did not feature amplitude dependence on echo attenuation or emitted click levels, except in a few combinations of the lowest values of these two variables. The results are explained by a hypothesis that partial forward masking of the echoes by the preceding emitted sonar pulses serves as a kind of automatic gain control in the auditory system of echolocating odontocetes. PMID:19354417

  13. 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 C