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Brainstem auditory evoked potentials following head injury.  


Brainstem auditory evoked potentials (BAEP) were examined in 40 patients with subjective disorders following closed head injury (CHI), with the established degree of recovery and performed CT-scan of the head. For all BAEP parameters the interval of normality was defined as 3 SD above and below mean value in the control group comprised of 20 healthy subjects. The upper limits of thus defined intervals of normality enabled the formation of four types of findings: type 1--normal finding that was registered in 23 (57.5%) patients; type 2 was a sum of individual findings with the prolonged interpeak latencies, but without the change of relative amplitude V:I--7 (17.5%) recordings; type 3--the findings where the fall of relative amplitude V:I was registered together with the prolongation of interpeak latency. It comprised of 4 (10%) recordings and the type 4 included 6 (15%) individual recordings with registered low RA V:I (0.8 or lower). The explanation of the most probable genesis of registered changes was presented. PMID:10838952

Savanovi?, V; Jovici?, A; Kitanoski, B; Magdi?, B; Umi?evi?, P; Cirkovi?, S; Savanovi?, L



Lesion Detection in MS Patients with and without Clinical Brainstem Disorders: Magnetic Resonance Imaging and Brainstem Auditory Evoked Potentials Compared  

Microsoft Academic Search

The findings of the present study can be summed up in the following points: (1) brainstem auditory evoked potentials (BAEP), as compared with magnetic resonance imaging (MRI), has a greater capacity and a lower cost in disclosing brainstem plaques both in MS patients with symptoms or signs of actual brainstem involvement and in clinically silent ones. This makes BAEP a

R. Capra; F. Mattioli; L. A. Vignolo; A. R. Antonelli; F. Bonfioli; J. Cappiello; P. Nicolai; G. Peretti; A. Orlandini



Brainstem auditory evoked potentials in cattle sedated with xylazine  

PubMed Central

This study examined the effect of sedation with xylazine on the brainstem auditory evoked potentials (BAEP) of cattle to determine whether sedation causes differences in waveform configuration, peak latencies, interpeak latencies, measurement time of the average count (2000 responses), and clinical signs. There were no significant differences between the sedation and no-sedation groups in peak latency of any stimulus intensities. In the sedation group, the baselines of waveforms were comparatively stabilized. Those in the no-sedation group were unstable, however, because the measurement can be influenced by excessive muscle movement. The present findings suggest that clinically, it is useful to use a sedative when measuring BAEP in cattle to control excessive movement of the cattle without influencing the peak latencies.

Arai, Shozo



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

PubMed Central

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 ? synuclein and/or ? 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.

Calderon-Garciduenas, Lilian; D'Angiulli, Amedeo; Kulesza, Randy J; Torres-Jardon, Ricardo; Osnaya, Norma; Romero, Lina; Keefe, Sheyla; Herritt, Lou; Brooks, Diane M; Avila-Ramirez, Jose; Delgado-Chavez, Ricardo; Medina-Cortina, Humberto; Gonzalez-Gonzalez, Luis Oscar



Utility of somatosensory evoked potentials in the early diagnosis of Bickerstaff's brainstem encephalitis  

Microsoft Academic Search

Bickerstaff's brainstem encephalitis (BBE) is characterized by diverse symptoms, and early diagnosis is often difficult, especially confusing with menigoencephalitis with cranial nerve involvements. Diagnostic role of anti-GQ1b antibody has been established, although its result is usually known late. Prompt diagnosis is preferred because immunotherapies are effective. Here we illustrate the usefulness of somatosensory evoked potentials (SEP) in the early diagnosis

H. Tsukamoto; M Sonoo; Y. Hatanaka; M. Kobayashi; T. Shimizu



F response and somatosensory and brainstem auditory evoked potential studies in HMSN type I and II.  

PubMed Central

To evaluate conduction along the proximal and distal segments of motor and sensory long limb nerves, as well as along the very short acoustic nerve, F response and somatosensory and brainstem auditory evoked potential were studied in a series of patients with hereditary motor and sensory neuropathy (HMSN) types I and II. A diffuse and comparable slowing of conduction in proximal and distal nerve segments, as well as along the acoustic nerve, seems to favour a primary myelin defect in HMSN I. F response and motor conduction velocity showed a similar derangement in both proximal and distal motor segments. Latencies of somatosensory evoked potentials were symmetrically prolonged and correlated with motor nerve impairment. Central conduction times were normal. Studies of brainstem auditory evoked potentials showed a high incidence of acoustic nerve involvement, the most evident abnormality being a statistically significant increase in the latency of the I wave. Our data seem to support the presence of primary myelinopathic damage in HMSN I.

Scaioli, V; Pareyson, D; Avanzini, G; Sghirlanzoni, A



Contribution from crossed and uncrossed brainstem structures to the brainstem auditory evoked potentials: a study in humans.  


The neural generators of the brainstem auditory evoked potentials (BAEPs) in humans are not completely known. Attempts to identify the anatomical location of the neural generators of the human BAEP based on the results of studies in animals commonly used in auditory experimentation have been difficult because of the considerable anatomical differences between the ascending auditory pathways in humans and animals. The authors of this study compared recordings obtained from different locations on the lateral side of the brainstem in six patients undergoing microvascular decompression surgery for a cranial nerve disorder affecting the fifth cranial nerve (i.e., trigeminal neuralgia). Ipsilateral click stimulation evoked prominent responses from the caudal aspect of the pons up to the junction between the pons and the midbrain, but all components of the responses with latencies shorter than 8 msec had smaller amplitudes when recorded at more rostral locations. Components with latencies in the range of peak V elicited by contralateral click stimulation had their largest amplitudes when recorded from the lateral brainstem at the level of the fourth cranial nerve (thus, close to the inferior colliculus). Earlier components of the contralateral responses (latencies in the range of the latency of peak III) had their largest amplitudes when recorded from the caudal lateral brainstem. The results of this study indicate that the part of the uncrossed auditory pathway that is located rostral to the cochlear nucleus contributes little to the farfield potentials (i.e., BAEP), and it is doubtful whether the contralateral response that can be recorded at the level of the cochlear nucleus contributes noticeably to the BAEP. PMID:7769942

Møller, A R; Jho, H D; Yokota, M; Jannetta, P J



Brain-stem trigeminal and auditory evoked potentials in multiple sclerosis: physiological insights.  


Thirty-six patients with multiple sclerosis were evaluated by means of brain-stem trigeminal and auditory evoked potentials. The brain-stem auditory evoked potentials (BAEPs) were abnormal in 26 patients (72.2%). Brain-stem trigeminal evoked potentials (BTEPs) yielded similar results, showing distorted waveforms and/or prolonged latencies in 25 patients (69.4%). As expected, the MRI proved to be the most efficient single test, revealing plaques in 86.4% of the patients evaluated. However, the diagnostic accuracy of MRI was lower than that provided by the combination of the BTEP and BAEP (88.9%). Moreover, in patients having signs of brain-stem involvement, the BTEP, alone and in combination with the BAEP, proved to be more sensitive than the MRI in revealing brain-stem lesions. Correlation between clinical and BTEP findings could be found only in those patients who presented with signs of trigeminal involvement such as trigeminal neuralgia or dysesthesiae. The analysis of the BTEP waveforms showed two distinct types of abnormality-a peripheral type and a central type-suggesting plaques in distinct locations. Both the BTEP and the BAEP demonstrated a correlation with the clinical course of the disease and the condition of the patient at the time of the evaluation. Relapse of the disease was associated with a marked prolongation of the central conduction time in the BTEP and in the BAEP, suggesting the application of such studies to the monitoring of unstable patients in the evaluation of new therapeutic protocols. PMID:8617153

Soustiel, J F; Hafner, H; Chistyakov, A V; Yarnitzky, D; Sharf, B; Guilburd, J N; Feinsod, M



Monitoring of brain-stem trigeminal evoked potentials. Clinical applications in posterior fossa surgery.  


Brain-stem trigeminal evoked potentials (BTEPs) were monitored intraoperatively in 17 patients during posterior fossa surgery. Satisfactory BTEP recording was performed in all patients without technical problems or interfering with the activity of the operating team. The BTEP was not altered by anesthetic agents or muscle relaxants. Intraoperative monitoring of the BTEP showed wave form alterations or increasing peak latencies in 10 patients. Among these patients, the BTEP demonstrated a dynamic correlation with the surgical process in 8 instances. Two major causative surgical manipulations were identified: cerebellar retraction in 4 cases and tumor dissection from the brain-stem in 6 cases. Withholding the dissection of the tumor, readjusting a cerebellar retractor or further modifying the surgical attitude resulted in partial or complete return of the wave form in 7 patients. The BTEP at the end of surgery proved to correlate with the immediate surgical outcome in most instances. We concluded that the intraoperative monitoring of the BTEP was feasible and suggested, despite the small number of patients, a potential value in the survey of brain-stem functions during posterior fossa surgery. PMID:7688280

Soustiel, J F; Hafner, H; Chistyakov, A V; Guilburd, J N; Zaaroor, M; Yussim, E; Feinsod, M



Differential maturation of brainstem auditory evoked potentials in preterm infants according to birthweight.  


Brainstem auditory evoked potentials (BAEPs) were recorded from 39 preterm infants, divided into 3 groups: small-for-gestational-age, with a birthweight less than or equal to 1500 g (SGA); appropriate-for-gestational-age, with a birthweight less than or equal to 1500 g (AGA1); and appropriate-for-gestational-age, with a birthweight higher than 1500 g (AGA2). A significant shortening of the I-V interval due to an increase in wave I latency was found in the SGA group. The lower-weight AGA group (AGA1) was never significantly different from the SGA group. Although there was no correlation between conceptional age and weight at the time of the examination for the studied population, negative correlations were found between wave I latency and weight at the time of the examination. These findings confirm previous research and suggest the existence of a link between weight and basal cochlear maturation. PMID:1342046

Soares, I; Collet, L; Desreux, V; Morgon, A; Salle, B



Hearing Screening of High-Risk Newborns with Brainstem Auditory Evoked Potentials: A Follow-Up Study.  

ERIC Educational Resources Information Center

The brainstem auditory evoked potential (BAEP) was evaluated as a hearing screening test in 168 high-risk newborns. The BAEP was found to be a sensitive procedure for the early identification of hearing-impaired newborns. However, the yield of significant hearing abnormalities was less than predicted in other studies using BAEP. (Author/CL)

Shannon, Dorothy A.; And Others



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


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

Shaw, N A



Brainstem auditory evoked potentials in a case of 'Manto syndrome', or spasmodic torticollis with thoracic outlet syndrome.  


A case of spasmodic torticollis with thoracic outlet syndrome observed for over 18 months is presented and discussed. Maximal head rotation (determining backward gaze) was associated with compression of the brachial plexus between the scaleni muscles and motor, sensory and trophic troubles in the hand. This new syndrome is called after the diviner Manto, quoted by Dante Alighieri in his 'Divina Commedia' (Inferno, XX, 52-56). The etiology was ascribed to subacute toxic effects of methylparathion. Brainstem Auditory Evoked Potentials (BAEPs) demonstrated severe brainstem involvement, maximal in the mesencephalic structures. Clinical and neurophysiological data improved on treatment with L-5-hydroxytryptophan. Finally, BAEPs returned to normal. PMID:6984700

Disertori, B; Ducati, A; Piazza, M; Pavani, M



Altered brainstem auditory evoked potentials in a rat central sensitization model are similar to those in migraine.  


Migraine symptoms often include auditory discomfort. Nitroglycerin (NTG)-triggered central sensitization (CS) provides a rodent model of migraine, but auditory brainstem pathways have not yet been studied in this example. Our objective was to examine brainstem auditory evoked potentials (BAEPs) in rat CS as a measure of possible auditory abnormalities. We used four subdermal electrodes to record horizontal (h) and vertical (v) dipole channel BAEPs before and after injection of NTG or saline. We measured the peak latencies (PLs), interpeak latencies (IPLs), and amplitudes for detectable waveforms evoked by 8, 16, or 32kHz auditory stimulation. At 8kHz stimulation, vertical channel positive PLs of waves 4, 5, and 6 (vP4, vP5, and vP6), and related IPLs from earlier negative or positive peaks (vN1-vP4, vN1-vP5, vN1-vP6; vP3-vP4, vP3-vP6) increased significantly 2h after NTG injection compared to the saline group. However, BAEP peak amplitudes at all frequencies, PLs and IPLs from the horizontal channel at all frequencies, and the vertical channel stimulated at 16 and 32kHz showed no significant/consistent change. For the first time in the rat CS model, we show that BAEP PLs and IPLs ranging from putative bilateral medial superior olivary nuclei (P4) to the more rostral structures such as the medial geniculate body (P6) were prolonged 2h after NTG administration. These BAEP alterations could reflect changes in neurotransmitters and/or hypoperfusion in the midbrain. The similarity of our results with previous human studies further validates the rodent CS model for future migraine research. PMID:24680742

Arakaki, Xianghong; Galbraith, Gary; Pikov, Victor; Fonteh, Alfred N; Harrington, Michael G



Effects of isoflurane on auditory evoked potentials in the cochlea and brainstem of guinea pigs.  


Electrophysiological recordings of the auditory system are commonly performed in deeply anesthetized animals. This study evaluated the effects of various concentrations of the volatile anesthetic isoflurane (1-3%) on the compound action potential (CAP), cochlear microphonic (CM) and auditory brainstem response (ABR). Recordings were initiated in the awake, lightly restrained animal. Anesthesia was induced with a single dose of Hypnorm (fentanyl and fluanisone). After tracheostomy increasing isoflurane concentrations were applied in N(2)O/O(2) via controlled ventilation. Data were compared to recordings in the awake animal using repeated measures ANOVA and Dunnett's post hoc test. On average, isoflurane dose-dependently suppressed the amplitude and increased the latency of the CAP. CM amplitude was suppressed. These effects were most profound at high frequencies and were typically significant at isoflurane concentrations of 2.5% and 3%. Amplitude and latency of the second negative peak of the CAP (N(2)) were affected to a greater extent compared to the first peak (N(1)). On average, isoflurane dose-dependently reduced the amplitude and increased the latency of the ABR. These effects were typically significant at an isoflurane concentration of 2%. Effects on peak IV and V were more pronounced compared to the early peaks I and III. PMID:19878711

Stronks, H Christiaan; Aarts, Mark C J; Klis, Sjaak F L



Normative Bilateral Brainstem Evoked Response Data for a Naval Aviation Student Population: Group Statistics.  

National Technical Information Service (NTIS)

A biomedical instrumentation capability has been developed and exploratory research has been initiated to investigate the potential contributions of brainstem auditory evoked response technology to aviation medicine. Brainstem data based upon simultaneous...

W. C. Hixson J. D. Mosko



The effect of broad-band noise on the binaural interaction components of human auditory brainstem-evoked potentials.  


Three-channel Lissajous trajectories (3-CLTs) of binaural interaction components (BI) of auditory brainstem potentials (ABEPs) were derived from 13 normally hearing adults by subtracting the response to binaural clicks from the algebraic sum of monaurally evoked responses to clicks. ABEPs were recorded in response to 65 dB nHL, alternating-polarity clicks, presented at a rate of 11/s. The procedure was repeated with clicks alone as well as with clicks with broad-band masking noise. Noise was presented at 25 and 45 dB nHL, producing a signal-to-noise ratio of +40 and +20 dB, respectively. All BI 3-CLTs included 6 planar segments (labeled BdI, BdII, BdIII, BeI, BeII and Bf) whose apex latencies, except Bf, increased with increasing noise level above 25 dB nHL, and whose durations, sizes, shapes and orientations did not change across noise levels. There were also significant increases in peak latencies of the BI from single channels vertex-mastoid and vertex-neck with increasing noise level. No significant change was found in the trajectory amplitude of apices, with the exception of apices BdIII and Bf whose amplitudes increased with increasing noise level. We suggest that the paradoxical increase in BI amplitude with masking noise may reflect a binaural enhancement of the effect of noise. The effects observed indicate that, whereas the response to clicks displays occlusion, the response to noise displays spatial facilitation at the brainstem level. PMID:7487645

Polyakov, A; Pratt, H



Episodic coma due to acute basilar artery migraine: correlation of EEG and brainstem auditory evoked potential patterns.  


Our patient presented with three episodes of deep coma in 5 weeks, followed by a complete recovery. The neuroradiological tests and spinal fluid analysis excluded structural lesions, including subarachnoid hemorrhage, from the diagnosis. A nonconvulsive status was excluded by 24-hour EEG monitoring. The EEGs and brainstem auditory evoked responses were abnormal during ictus, but they reversed to normal with the clinical recovery. Timely neurophysiological tests helped in the diagnosis of basilar artery migraine. PMID:8420697

Ganji, S; Hellman, S; Stagg, S; Furlow, J



[The relationship of brainstem auditory evoked potential to cerebral blood flow volume in with vertebrobasilar transient ischemic vertigo].  


This study was aimed at the relationship of brain-stem auditory evoked potential(BAEP) with cerebral blood flow(CBF) volume and vascular pathological changes in patients with vertebro-basilar transient ischemic vertigo (VBTIV). 65 patients were examined by magnetic resonance angiography(MRA), transcranial Dopplar(TCD) and BAEP; 26 controls were examined by MRA and TCD. In the patient group, MRA showed that vascular pathological changes were obvious in 50 patients, and obscure or absent in 15 patients. The CBF volume [112.3-278.9 ml/min (2s)] of control group was higher than that (48.0-262.0 ml/min) of the patients group (t = 2.43, P < 0.01) in which 15 patients had low CBF volume and 50 patients had normal CBF volume. The BAEP of 47(72.3%) patients was abnormal. Out of 15 patients with low CBF volume, 14(93.3%) had abnormal BAEP, but out of 50 patients with normal CBF volume, only 33(66%) patients had abnormal BAED (chi 2 = 4.34, P < 0.05). In the 50 patients with obscure obvious vascular pathological changes, 40(80%) patients had abnormal BAEP, but in the 15 patients with obscure or without the changes, only 7(43.3%) patients had abnormal BAEP (chi 2 = 4.86, P < 0.05). These results suggested that there might be a close relationship of BAEP with CBF volume and vascular pathological changes. PMID:12501621

Tang, K; Chen, R; Cal, R; Zhou, J; Huang, J; Long, W; Mo, Z



The location by early auditory evoked potentials (EAEP) of acoustic nerve and brainstem demyelination in multiple sclerosis (MS)  

Microsoft Academic Search

Tone pips of suprathreshold intensities elicit an acoustic nerve response (I) and six low amplitude brainstem potentials (II–VII) during the initial 10 ms. Seven waves were studied in 40 control subjects and 5 waves (I–V) in 47 patients with MS. The results suggest involvement of the auditory pathway of 24 of 27 patients in the clinically “definite”, of 5 of

K. Maurer; E. Schäfer; H. C. Hopf; H. Leitner



A comparison of neural network and Bayes recognition approaches in the evaluation of the brainstem trigeminal evoked potentials in multiple sclerosis.  


This article describes the application of Multi-Layer Perceptron (MLP), Probabilistic Neural Network and Kohonen's Learning Vector Quantization to the problem of diagnosing Multiple Sclerosis. The classification information is obtained from brainstem trigeminal evoked potential. The performance of the neural networks based classifiers is compared with that of the human experts and the Bayes classifier. The ability of the MLP classifier to generalize is far better than that of the Bayes classifier. The efficiency of the neural network based classifiers in conjunction with several types of well-known evoked potential features, such as Fourier transform space, latency and temporal wave, is examined. Although a large clinical data base would be necessary, before this approach can be fully validated, the initial results are promising. PMID:9032009

Guterman, H; Nehmadi, Y; Chistyakov, A; Soustiel, J F; Feinsod, M



Developmental normo-maturation of brainstem auditory evoked potentials in children with asymptomatic meningo-myelocele during the first year of life.  


It is difficult to predict the onset of clinical symptoms due to Chiari II malformation. Brainstem auditory evoked potentials (BAEPs) may be useful to select potential candidates for surgery. We studied 158 BAEPs in 134 asymptomatic children with meningomyelocele (MMC) during the first year of life. Both wave latencies (WLs) and interpeak latencies (IPLs) in asymptomatic children with MMC gradually became shorter during the first year of life. In particular, the shortening of III-V IPLs was observed in the asymptomatic children with MMC from 2 or 3 weeks to 4-6 months of age. This may be a characteristic parameter of the development of the intrinsic brainstem function in patients with MMC. Comparison of these data on BAEPs in asymptomatic children with MMC with the published data on BAEPs in normal neonates and infants showed that the maturation of brainstem function was delayed in the asymptomatic children with MMC during the first year of life. These data on asymptomatic neonates and infants with MMC could potentially be a good reference for selecting the modalities of treatment in patients with MMC associated with symptomatic Chiari II malformation. PMID:9137856

Fujii, M; Tomita, T; McLone, D G; Grant, J A; Stack, C V; Mori, K



Brainstem auditory-evoked potential assessment of auditory function and congenital deafness in llamas (Lama glama) and alpacas (L. pacos).  


Auditory function of llamas and alpacas was assessed objectively by means of brainstem auditory-evoked response audiometry (BAER) to establish the normal hearing range and to test the hypothesis of a correlation between blue eyes, white coat, and deafness. Sixty-three camelids were available for the study. Thirteen animals had blue irides; 1 animal had 1 blue and 1 pigmented iris. Wave latencies, amplitudes, and interpeak latencies were measured under general anesthetic. Click stimuli (dB [HL]) were delivered by an insert earphone. Four to five positive peaks could be detected; waves I, II, and V were reproducible; wave II appeared infrequently; and wave IV generally merged with wave V to form a complex. Peak latencies decreased and peak amplitudes increased as stimulus intensity increased. A hearing threshold level of 10-20 dB (HL) was proposed as the normal range in llamas and alpacas. None of the animals with pigmentation of coat and iris showed any degree of hearing impairment. Seven of the 10 blue-eyed, pure-white animals were bilaterally deaf and one of them was unilaterally deaf. However, 2 blue-eyed, white animals exhibited normal hearing ability. Three blue-eyed animals with pigmented coat did not show any hearing impairment. All white animals with normal iris pigmentation had normal auditory function; so did the 1 animal with 1 normal and 1 blue iris. The high frequency (78%) of bilaterally deaf animals with pure white coat and blue iris pigmentation supports the hypothesis of a correlation between pigmentation anomalies and congenital deafness in llamas and alpacas. PMID:16231723

Gauly, Matthias; Vaughan, Jane; Hogreve, Saskia K; Erhardt, Georg



Classification of brain-stem trigeminal evoked potentials in multiple sclerosis, minor head injuries and post-concussion syndrome pathologies by similarity measurements.  


In this study measurements obtained from brain-stem trigeminal evoked potentials (BTEP) are applied to the problem of diagnosing Multiple Sclerosis (MS) and Post-concussion syndrome (PCS). We present a simplistic model that depicts the BTEP waveform as the linear combination of a set of filters excited by a short stimulus. The relation between the BTEP latencies and the 1st to 4th harmonic components is shown. The performance of a fuzzy similarity measure based classifier is compared with that of human experts. The efficiency of the proposed classifier in conjunction with delay time and amplitude features is examined. Using this novel approach, a classification rate of 93.55% and 84.1% for MS and PCS pathologies, respectively, was achieved. This performance compares favorably to the classification rates of 84.28% for MS and 70.47% for PCS pathologies achieved by human experts. PMID:11137473

Guterman, H; Nehmadi, Y; Chistyakov, A; Soustiel, J; Hafner, H; Feinsod, M



Speech Evoked Auditory Brainstem Responses: A New Tool to Study Brainstem Encoding of Speech Sounds  

Microsoft Academic Search

The neural encoding of speech sound begins in the auditory nerve and travels to the auditory brainstem. Non speech stimuli\\u000a such as click or tone bursts stimulus are used to check the auditory neural integrity routinely. Recently Speech evoked Auditory\\u000a Brainstem measures (ABR) are being used as a tool to study the brainstem processing of Speech sounds. The aim of

Sujeet Kumar Sinha; Vijayalakshmi Basavaraj



Inhalational Exposure to Carbonyl Sulfide Produces Altered Brainstem Auditory and Somatosensory-Evoked Potentials in Fischer 344N Rats  

Microsoft Academic Search

Carbonyl sulfide (COS), a chemical listed by the original Clean Air Act, was tested for neurotoxicity by a National Institute of Environmental Health Sciences\\/National Toxicology Program and U.S. Environmental Protection Agency collaborative investiga- tion. Previous studies demonstrated that COS produced cortical and brainstem lesions and altered auditory neurophysiological responses to click stimuli. This paper reports the results of ex- panded

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



Gap prepulse inhibition and auditory brainstem-evoked potentials as objective measures for tinnitus in guinea pigs  

PubMed Central

Tinnitus or ringing of the ears is a subjective phantom sensation necessitating behavioral models that objectively demonstrate the existence and quality of the tinnitus sensation. The gap detection test uses the acoustic startle response elicited by loud noise pulses and its gating or suppression by preceding sub-startling prepulses. Gaps in noise bands serve as prepulses, assuming that ongoing tinnitus masks the gap and results in impaired gap detection. This test has shown its reliability in rats, mice, and gerbils. No data exists for the guinea pig so far, although gap detection is similar across mammals and the acoustic startle response is a well-established tool in guinea pig studies of psychiatric disorders and in pharmacological studies. Here we investigated the startle behavior and prepulse inhibition (PPI) of the guinea pig and showed that guinea pigs have a reliable startle response that can be suppressed by 15 ms gaps embedded in narrow noise bands preceding the startle noise pulse. After recovery of auditory brainstem response (ABR) thresholds from a unilateral noise over-exposure centered at 7 kHz, guinea pigs showed diminished gap-induced reduction of the startle response in frequency bands between 8 and 18 kHz. This suggests the development of tinnitus in frequency regions that showed a temporary threshold shift (TTS) after noise over-exposure. Changes in discharge rate and synchrony, two neuronal correlates of tinnitus, should be reflected in altered ABR waveforms, which would be useful to objectively detect tinnitus and its localization to auditory brainstem structures. Therefore, we analyzed latencies and amplitudes of the first five ABR waves at suprathreshold sound intensities and correlated ABR abnormalities with the results of the behavioral tinnitus testing. Early ABR wave amplitudes up to N3 were increased for animals with tinnitus possibly stemming from hyperactivity and hypersynchrony underlying the tinnitus percept. Animals that did not develop tinnitus after noise exposure showed the opposite effect, a decrease in wave amplitudes for the later waves P4–P5. Changes in latencies were only observed in tinnitus animals, which showed increased latencies. Thus, tinnitus-induced changes in the discharge activity of the auditory nerve and central auditory nuclei are represented in the ABR.

Dehmel, Susanne; Eisinger, Daniel; Shore, Susan E.



The Theoretical Distribution of Evoked Brainstem Activity in Preterm, High-Risk, and Healthy Infants.  

ERIC Educational Resources Information Center

Determines the frequency distribution of Brainstem Auditory Evoked Potential variables (BAEP) for premature babies at different stages of development--normal newborns, infants, young children, and adults. The author concludes that the assumption of normality underlying most "standard" statistical analyses can be met for many BAEP measures.…

Salamy, A.



Brainstem evoked response audiometry (BAER) in neonates with hyperbilirubinemia  

Microsoft Academic Search

Objective: To evaluate Brainstem Evoked Response Audiometry (BAER) as an objective testing of hearing assessment in icteric babies\\u000a and correlate the abnormalities with serum bilirubin levels.Methods: BAER recordings were taken in 30 icteric ferm neonates at birth, at peak of serum bilirubin levels and on a follw-up visit\\u000a at 2–4 months of age.Results: Mean latency of waves and interwave intervals

Pramod Sharma; N. P. Chhangani; Kesh Ram Meena; Rakesh Jora; Navratan Sharma; B. D. Gupta



Kcna1 gene deletion lowers the behavioral sensitivity of mice to small changes in sound location and increases asynchronous brainstem auditory evoked potentials but does not affect hearing thresholds.  


Sound localization along the azimuth depends on the sensitivity of binaural nuclei in the auditory brainstem to small differences in interaural level and timing occurring within a submillisecond epoch and on monaural pathways that transmit level and timing cues with high temporal fidelity to insure their coincident arrival at the binaural targets. The soma and axons of these brainstem neurons are heavily invested with ion channels containing the low-threshold potassium channel subunit Kv1.1, which previous in vitro and in vivo studies suggest are important for regulating their high input-output correspondence and temporal synchrony. We compared awake Kcna1-null mutant (Kcna1-/-) mice lacking Kv1.1 with Kcna1+/+ mice to determine whether Kv1.1 activity contributes to sound localization and examined anesthetized mice for absolute hearing thresholds for suprathreshold differences that may be revealed in the waveforms of auditory brainstem response potentials. The awake -/- mice tested with reflex modification audiometry had reduced sensitivity to an abrupt change in the location of a broad band noise compared to +/+ mice, while anesthetized -/- mice had normal absolute thresholds for tone pips but a high level of stimulus-evoked but asynchronous background activity. Evoked potential waveforms had progressively earlier peaks and troughs in -/- mice, but the amplitude excursions between adjacent features were identical in the two groups. Their greater excitability and asynchrony in suprathreshold evoked potentials coupled with their normal thresholds suggests that a disruption in central neural processing in -/- mice and not peripheral hearing loss is responsible for their poor sound localization. PMID:22396426

Allen, Paul D; Ison, James R



Kcna1 gene deletion lowers the behavioral sensitivity of mice to small changes in sound location and increases asynchronous brainstem auditory evoked potentials, but does not affect hearing thresholds  

PubMed Central

Sound localization along the azimuth depends on the sensitivity of binaural nuclei in the auditory brainstem to small differences in interaural level and timing occurring within a sub-millisecond epoch, and on monaural pathways that transmit level and timing cues with high temporal fidelity to insure their coincident arrival at the binaural targets. The soma and axons of these brainstem neurons are heavily invested with ion channels containing the low-threshold potassium channel subunit Kv1.1, which previous in-vitro and in-vivo studies suggest are important for regulating their high input-output correspondence and temporal synchrony. We compared awake Kcna1 null mutant (?/?) mice lacking Kv1.1 with +/+ mice to determine if Kv1.1 activity contributes to sound localization, and examined anesthetized mice for absolute hearing thresholds for suprathreshold differences that may be revealed in the waveforms of auditory brainstem response potentials. The awake ?/? mice tested with reflex modification audiometry had reduced sensitivity to an abrupt change in the location of a broad band noise compared to +/+ mice, while anesthetized ?/? mice had normal absolute thresholds for tone pips but a high level of stimulus-evoked but asynchronous background activity. Evoked potential waveforms had progressively earlier peaks and troughs in ?/? mice but the amplitude excursions between adjacent features were identical in the two groups. Their greater excitability and asynchrony in suprathreshold evoked potentials coupled with their normal thresholds suggests that a disruption in central neural processing in ?/? mice and not peripheral hearing loss is responsible for their poor sound localization.

Allen, Paul D.; Ison, James R.



[Evoked potentials in patients with secondary headaches].  


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. PMID:20436441

Iakupov, E Z; Kuznetsova, E A



Brainstem Maturation after Antenatal Steroids Exposure in Premature Infants as Evaluated by Auditory Brainstem-Evoked Response  

Microsoft Academic Search

OBJECTIVE: Antenatal steroids result in fetal lung maturation, but may retard brain development. Auditory brainstem-evoked response (ABR) is a noninvasive assessment of brainstem maturation. The objective of this study was to determine if antenatal steroids affect brainstem maturation in infants ?32 weeks gestational age (GA).DESIGN\\/METHODS: Bilateral monaural ABR were performed within the first 24 hours using 80 db nHL unfiltered

Sanjiv B Amin; Mark S Orlando; Larry E Dalzell; Kathleen S Merle; Ronnie Guillet



Modified brainstem auditory evoked responses in patients with non-brainstem compressive cerebral lesions.  


The brainstem auditory evoked response (BAER) is sensitive to pontomesencephalic integrity, transtentorial brain herniation, and at times increased intracranial pressure (ICP). The authors report their experience utilizing a recently described rapid rate, binaural, click and 1,000-Hz tone-burst modification of the BAER (MBAER) in 22 symptomatic non-trauma patients with non-brainstem compressive space-taking cerebral lesions. The majority presented with mild to moderate clinical signs suggestive of increased ICP, and focal neurological deficits. The cerebral lesions, mostly tumors (17), averaged 4-5 cm in diameter, with radiological signs of mass effect such as flattening of the sulci, midline shift, and narrowing of the basal cisterns. A number of significant changes in Wave V and V (n) latency and less so amplitude were found in patients compared with age-matched normal volunteers, as well as those again studied after surgical decompression. Similar MBAER changes had been noted in normal volunteers placed in a dependent head position. Possible mechanisms to explain these findings are discussed. The methodology shows promise and if combined with automated peak recognition could make Neuro ICU monitoring practical. PMID:22327668

Stone, James L; Fino, John; Vannemreddy, Prasad; Charbel, Fady



An algorithm for monitoring sensory evoked potentials  

Microsoft Academic Search

Brainstem auditory evoked potentials (BAEP) testing is used extensively to monitor auditory function during retromastoid craniectomies\\u000a for microvascular decompression. The latency between BAEP peaks can change notably over a period of several seconds or minutes,\\u000a a much shorter time than is necessary to acquire and analyze a conventionally averaged BAEP. This article describes a continuous\\u000a monitoring algorithm that detects both

J. R. Boston



Motion evoked vestibular potentials.  

National Technical Information Service (NTIS)

Motion evoked potentials were collected from subjects while they were rotated from side to side in a seated postion. The MERS were bipahsic with major component mean latencies of 278 MSEC It is concluded that the MERS are of brain origin and not due to ar...

W. D. Fraser N. Black D. E. Eastman J. P. Landolt




EPA Science Inventory

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


Tobacco and Evoked Potential  

Microsoft Academic Search

Significant changes were found in two indices of the averaged visual evoked potentials in nine smokers after 12 and 36 hours of abstinence and after resumption of smoking. There was a decrease of the amplitude envelope accompanying withdrawal and an increase with resumption of smoking. These changes are consistent with the contention that tobacco increases arousal. Amplitude changes were found

R. A. Hall; M. Rappaport; H. K. Hopkins; R. Griffin



Auditory evoked potentials.  


Auditory evoked potentials (AEPs) have become an integral part of the current otologic/audiologic test battery. With these techniques, synchronous neural activity can be examined from the peripheral end organ of hearing up to the cortical structures responsible for audition. The clinical applications of AEPs range from their use as an indicator of auditory sensitivity in patients who either cannot or will not respond in a conventional behavioral test situation to their use in the diagnosis and monitoring of various otologic and neurologic disorders. As such, measurement of AEPs allows the clinician a unique glimpse of the auditory system. PMID:1857616

Ruth, R A; Lambert, P R



Evaluation of various brain structures in multiple sclerosis with multimodality evoked potentials, blink reflex and nystagmography  

Microsoft Academic Search

Pattern reversal visual evoked potentials (VEP), blink reflexes, auditory brainstem evoked potentials (ABEP), spinal and scalp recorded somatosensory evoked potentials (SSEP), and nystagmographic records were investigated in 55 patients with multiple sclerosis (MS), who were separated in different categories of probability according to the clinical history, symptoms, and signs. The combined use of different electrophysiological methods forms a sensitive battery

W. Tackmann; H. Strenge; R. Barth; A. Sojka-Raytscheff




EPA Science Inventory

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


Newborn Auditory Brainstem Evoked Responses (ABRs): Longitudinal Correlates in the First Year.  

ERIC Educational Resources Information Center

Aimed to determine to what degree newborns' auditory brainstem evoked responses (ABRs) predict delayed or impaired development during the first year. When 93 infants' ABRs were evaluated at three, six, and nine months, newborn ABR was moderately sensitive for detecting hearing impairment and more sensitive than other indicators in detecting…

Murray, Ann D.




EPA Science Inventory

Two experiments were conducted to determine the effects of hypothermia and pentobarbital anesthesia, alone and in combination, on the brainstem auditory evoked responses (BAERs) of rats. n experiment I, unanesthetized rats were cooled to colonic temperatures 0.5 and 1.0 degrees C...


Auditory brainstem potentials in uraemia.  


Evoked response audiometry was carried out to assess the viability of the auditory pathway in haemodialysed patients. The latency of the waves III and V and I-V interpeak latencies were significantly longer in the renal patients compared to the control group. The I-V interpeak latency was longer in 8 of our 13 patients than the upper limit (4.38 ms) in our laboratory. The possible cause for the central auditory dysfunction may be multifactorial, including the effect of metastatic calcifications, repeated occurrence of disequilibrium syndrome, or some small, molecular, toxic, metabolic substance. The significance of the different factors may vary among different haemodialysis centres. PMID:8446393

Küstel, M; Büki, B; Gyimesi, J; Makó, J; Komora, V; Ribári, O



Human Evoked Potentials. Applications and Problems.  

National Technical Information Service (NTIS)

Human Evoked Potentials presents a multidisciplinary selection of recent papers discussing such topics as event related potentials in development, aging and dementia, color evoked potentials, and spatial and temporal distribution of olfactory evoked poten...

D. Lehman E. Callaway



Anesthesia and evoked potentials: Overview  

Microsoft Academic Search

Summary  Evoked potentials are increasingly used for intraoperative monitoring. Their use is based on their ability to detect early\\u000a changes caused by surgical maneuvers which may result in post operative deficits. However, not all changes are surgically\\u000a related and any decrease in the non surgical causes of evoked potential changes increases the yield of intraoperative monitoring.\\u000a In this review I will

Antoun Koht



Investigation of auditory processing disorder and language impairment using the speech-evoked auditory brainstem response.  


This study investigated whether there are differences in the Speech-Evoked Auditory Brainstem Response among children with Typical Development (TD), (Central) Auditory Processing Disorder (C)APD, and Language Impairment (LI). The speech-evoked Auditory Brainstem Response was tested in 57 children (ages 6-12). The children were placed into three groups: TD (n = 18), (C)APD (n = 18) and LI (n = 21). Speech-evoked ABR were elicited using the five-formant syllable/da/. Three dimensions were defined for analysis, including timing, harmonics, and pitch. A comparative analysis of the responses between the typical development children and children with (C)APD and LI revealed abnormal encoding of the speech acoustic features that are characteristics of speech perception in children with (C)APD and LI, although the two groups differed in their abnormalities. While the children with (C)APD might had a greater difficulty distinguishing stimuli based on timing cues, the children with LI had the additional difficulty of distinguishing speech harmonics, which are important to the identification of speech sounds. These data suggested that an inefficient representation of crucial components of speech sounds may contribute to the difficulties with language processing found in children with LI. Furthermore, these findings may indicate that the neural processes mediated by the auditory brainstem differ among children with auditory processing and speech-language disorders. PMID:22974503

Rocha-Muniz, Caroline N; Befi-Lopes, Debora M; Schochat, Eliane



Somatosensory evoked potentials in syringomyelia.  

PubMed Central

The two types of upper limb somatosensory evoked potential abnormality observed in nine patients with syringomyelia were reduced amplitude or absent cervical potentials and an abnormal central conduction time. Although this pattern of abnormalities resembles that observed in other intrinsic spinal cord lesions, it differs from peripheral nerve diseases and cervical radiculopathy in which the central conduction time is normal.

Anderson, N E; Frith, R W; Synek, V M



Potenciais evocados auditivos em indivíduos acima de 50 anos de idade***** Auditory evoked potentials in individuals over 50 years  

Microsoft Academic Search

Background: auditory evoked potentials. Aim: to describe the results of brainstem auditory evoked potentials (PEATE), middle latency auditory evoked potentials (PEAML) and cognitive potential (P300) in individuals over 50 years. Method: this study was developed at the Speech and Hearing Investigation Laboratory in Auditory Evoked Potentials of the Speech-Language and Hearing Course of the Department of Physiotherapy, Speech-language and Hearing

Carla Gentile Matas; Valdete Alves; Valentins dos Santos Filha; Melissa Mitsue Cunha; Pires Okada; Juliana Reis Resque


Test-Retest Reliability of the Speech-Evoked Auditory Brainstem Response in Young Adults  

PubMed Central

Objective The speech-evoked auditory brainstem response (ABR) provides an objective measure of subcortical encoding of complex acoustic features. However, the intrasubject reliability of this response in both optimal and challenging listening conditions has not yet been systematically documented. This study aimed to evaluate test-retest reliability of the speech-evoked ABR in young adults. Methods In each of two sessions, ABRs were obtained with: 1) a 170 ms/da/ syllable presented in quiet as well as 2-talker and 6-talker babble background noise conditions and 2) a 40 ms/da/ syllable presented in quiet. Test-retest reliability of the responses was analyzed in the frequency and time domains. Results The speech-evoked ABR does not vary significantly across sessions within individuals on measures of temporal encoding (i.e., peak latencies, stimulus-to-response and response-to-response measures), frequency representation and response magnitude. Conclusions The subcortical auditory pathway produces a response to a complex sound that is stable and replicable from session to session. Significance By demonstrating the high degree of replicability in optimal and challenging listening conditions, the applicability of the speech-evoked ABR may be increased to examining a range of auditory processing abilities in clinical and research settings.

Song, Judy H.; Nicol, Trent; Kraus, Nina



Serial evoked potentials and outcome in cerebrovascular critical care patients.  


Median-nerve evoked somatosensory evoked potentials (SEPs) and brainstem auditory evoked potentials (BAEPs), examined early in the course of patients suffering from cerebrovascular disease, correlate statistically significantly with outcome. Little is known about the changes of evoked potentials in the course of disease and their correlation to outcome. In a series of 215 patients (75 supratentorial infarctions, 36 infratentorial infarctions, 58 supratentorial hemorrhages, 18 infratentorial hemorrhages, and 28 aneurysmatic subarachnoid hemorrhages) requiring neurologic intensive care treatment, we prospectively examined the correlation between the findings of serial SEPs and BAEPs and outcome at 4 weeks. Evoked potentials were examined after admission, after 1 week, and after 2 weeks. The findings were classified in 4 categories (normal, unilateral or bilateral pathologic findings, unilaterally attenuated, and bilaterally attenuated). Clinical outcome was determined by classification according to the Glasgow Outcome Scale (death, persistent vegetative state, severely incapacitated, mildly incapacitated, and recovery). Statistical evaluation was performed using Fisher's exact test for all variables. In all subgroups, SEPs correlated statistically significantly with outcome at all three examinations. No correlation was found for BAEPs at first examination in infratentorial disease, nor at second examination in subarachnoid hemorrhages. In all other cases, SEPs and BAEPs were correlated statistically significantly with outcome at all three examination timepoints. PMID:10928644

Haupt, W F; Birkmann, C; Halber, M



Evoked potentials in children with Wilson's disease.  


We assessed multimodal evoked potentials (EPs) in 13 children with newly diagnosed neurologically symptomatic Wilson's disease (WD) and in their first degree symptom-free relatives, consisting of seven presymptomatic and 15 asymptomatic siblings and 22 asymptomatic parents. EP abnormalities of at least one modality and one side stimulation were observed in 38.5% of patients, 42.9% of presymptomatic siblings, 21.4% of asymptomatic siblings and 18.2% of parents. Patients tended to have more prolonged central latencies of EPs. However, the left I-V interpeak brainstem auditory EP latency difference was the only one to reach at the statistical significance (P = 0.001). Abnormal VEP P100 latency was detected more frequently in presymptomatic siblings than those in asymptomatic ones (42.9% vs 7.1%, P = 0.049). In all relatives, other diagnostic tests including electroencephalography, electromyography and head magnetic resonance imaging (MRI) for subclinical nervous system involvement and Kayser-Fleischer rings examination yielded normal results. In pre/asymptomatic siblings, genetic and biochemical studies may aid to initiate treatment prior to the development of permanent tissue damage. Our results indicate that abnormal EPs may signal unique pathological finding in some subjects. Importantly, these abnormalities occur earlier than Kayser-Fleischer rings and MRI lesions. In early stages of WD, EP recordings may, therefore, be used to help decide on treatment initiation and treatment efficacy evaluation. Moreover, EP recordings can readily be added to family screening studies. PMID:12142063

Topcu, Meral; Topcuoglu, Mehmet Akif; Kose, Gulsen; Nurlu, Gulay; Turanli, Guzide



Median Nerve Somatosensory Evoked Potentials Recorded with Cephalic and Noncephalic References in Central and Peripheral Nervous System Lesions  

Microsoft Academic Search

Somatosensory evoked potentials (SSEP) to electrical stimulation of the median nerve by using cephalic and noncephalic references were studied to detect the generator sources of short latency evoked potentials in 29 patients with cerebral, brainstem, spinal and peripheral nerve lesions.Patients were divided into six groups according to the localization of their lesions: group 1: cortical and subcortical lesions, group 2:

Umit Hidir Ulas; Fatih Özdag; Erdal Eroglu; Zeki Odabasi; Yasar Kutukcu; Seref Demirkaya; Zeki Gökçil; Kemal Hamamcioglu; Okay Vural



Progressive hearing loss in an infant in a neonatal intensive care unit as revealed by auditory evoked brainstem responses  

Microsoft Academic Search

We herein report a case of a 14-month-old infant who revealed a progressive hearing loss by repeated auditory evoked brainstem responses (ABR) during his 1 year stay in the neonatal intensive care unit (NICU). He was born prematurely with asphyxia, hyperbilirubinemia and respiratory distress. During his 1 year stay in the NICU he was under constant mechanical ventilation. Repeated ABRs

Lihui Huang; Kimitaka Kaga; Kazuhiro Hashimoto




EPA Science Inventory

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


Evoked-Potential Correlates of Stimulus Uncertainty  

Microsoft Academic Search

The average evoked-potential waveforms to sound and light stimuli recorded from scalp in awake human subjects show differences as a function of the subject's degree of uncertainty with respect to the sensory modality of the stimulus to be presented. Differences are also found in the evoked potential as a function of whether or not the sensory modality of the stimulus

Samuel Sutton; Margery Braren; Joseph Zubin; E. R. John



Intraoperative Monitoring Using Somatosensory Evoked Potentials  

Microsoft Academic Search

Objective: To provide an educational service to the intraoperative neurophysiologist community by publishing a position statement by the American Society of Neurophysiological Monitoring on the recommended appropriate and correct use of somatosensory evoked potentials as an intraoperative neurophysiological monitoring tool to protect patient well-being during surgery. This position statement presents the somatosensory evoked potential utilization basis, relevant anatomy, patient preparation,

J. Richard Toleikis



[Temporal-spatial analysis of evoked potentials].  


Evoked potentials are widely used in clinical neurophysiology. The conventional analysis methods of evoked potentials are based on the waves in time domain. Analysis based on time-spatial domain will provide more information than simple time domain analysis. The existing temporal-spatial analysis methods, such as microstate, frequency domain analysis and event-related coherence, are introduced in this paper. PMID:11951507

Li, Yong; Gao, Xiaorong; Gao, Shangkai



[Monitoring intraoperative processing of acoustic stimuli with auditory evoked potentials].  


130 Patients undergoing elective intra-abdominal, gynaecological, urological or cardiac surgery were studied after institutional approval and informed consent. In all patients auditory-evoked potentials (AEP) were recorded in the awake state and during general anaesthesia. Latencies of the peaks V, Na, Pa, Nb and P1 were measured. V belongs to the brainstem-generated potentials, which demonstrates that auditory stimuli were correctly transduced. Na, Pa, Nb, P1 are generated in the primary auditory cortex of the temporal lobe. During anaesthesia with isoflurane, enflurane, thiopentone, etomidate and propofol the peak V remains unchanged, whereas the mid-latency auditory-evoked potentials (MLAEP) show marked increases in latencies and decreases in amplitudes or are even completely suppressed. This indicates a successful stimulus transmission up to the level of the brainstem and midbrain. However, stimulus processing in the primary auditory cortex is blocked. Under increasing end-expiratory concentrations of isoflurane MLAEP show a dose-dependent increase of latencies and decrease of amplitudes. Under surgical anaesthesia with 1.2 vol%, MLAEP are nearly completely suppressed. A different picture can be seen when MLAEP were recorded during anaesthesia with the receptor-specific anaesthetics midazolam, flunitrazepam, diazepam, fentanyl and ketamine. During anaesthesia with receptor-specific anaesthetics, the brainstem peak V as well as the mid-latency components remain nearly unchanged compared with AEP from awake patients. This indicates that auditory stimuli reach the primary auditory cortex and are processed at a primary cortical level. With increasing doses of fentanyl one can observe only a significant decrease of amplitudes for the late component P1.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8305868

Schwender, D; Madler, C; Klasing, S; Pöppel, E; Peter, K



Ultra Fast Quantification of Hearing Loss by Neural Synchronization Stabilities of Auditory Evoked Brainstem Activity  

Microsoft Academic Search

Recently, we proposed a new novelty detection paradigm for the fast detection of hearing thresholds using single sweeps of auditory evoked potentials as efficient approach to newborn hearing screening. Such a method might prevent currently used time consuming averaging procedures which require the state of spontaneous sleep, sedation, or narcosis of the newborns when using such systems in universal newborn

F. I. Corona-Strauss; W. Delb; M. Bloching; D. J. Strauss



The multifocal visual evoked potential.  


With the multifocal technique, visual evoked potentials (VEPs) can be recorded simultaneously from many regions of the visual field. For the multifocal VEP (mfVEP), the patient views a display that typically contains 60 sectors, each with a checkerboard pattern. The display covers about the same retinal area as the 24-2 Humphrey visual field (HVF). However, due to the scaling of the sectors of the mfVEP display, the fields are sampled differently by the mfVEP and HVF. To assess local defects in the visual field, the mfVEP responses must be compared with normal controls. These comparisons require relatively sophisticated analyses and software. Whereas the mfVEP can be recorded relatively easily with the same equipment used to record multifocal electroretinograms (mfERGs), the software needed to perform the analysis is not yet widely available. The mfVEP is valuable for ruling out non-organic visual loss, diagnosing and following patients with optic neuritis/multiple sclerosis, evaluating patients with unreliable or questionable HVFs, and following disease progression. When combined with the mfERG, diseases of the outer retina (before the retinal ganglion cells) can be distinguished from diseases of the ganglion cells and/or optic nerve. The difficulties encountered in recording and analyzing mfVEP responses are greater than those involved in full-field VEP testing. Thus, in its current form, the mfVEP is best recorded and interpreted by ophthalmologists and electrophysiologists experienced with the technique. However, this technique is developing rapidly; advances in commercial hardware and software are expected in the near future. PMID:14663311

Hood, Donald C; Odel, Jeffrey G; Winn, Bryan J



Brainstem auditory-evoked response (BAER) in client-owned pet ferrets with normal hearing.  


The objective of this study was to evaluate the feasibility of brainstem auditory-evoked response (BAER) testing in pet ferrets in a clinical setting, and to describe a routine method and baseline data for normal hearing ferrets for future investigation of deafness in this species. Twenty-eight clinically normal client-owned ferrets were included. BAER measurements were recorded under general anaesthesia (isoflurane delivered by mask), from subcutaneously placed needle electrodes. A 'click' stimulus applied by insert earphone with an intensity of 90?dB sound pressure level (SPL) was used. The final BAER waveform represents an average of 500 successive responses. Morphology of the waveform was studied; amplitude and latency measures were determined and means were calculated. The BAER waveform of the normal ferret included 4 reproducible waves named I, II, III and V, as previously described in dogs and cats. Measurements of latencies are consistent with previous laboratory research using experimental ferrets. In the present study, a reliable routine protocol for clinical evaluation of the hearing function in the pet ferret was established. This procedure can be easily and safely performed in a clinical setting in ferrets as young as eight weeks of age. The prevalence of congenital deafness in ferrets is currently unknown but may be an important consideration, especially in ferrets with a white coat. BAER test is a useful screening for congenital deafness in this species. PMID:24714054

Piazza, S; Huynh, M; Cauzinille, L



The latency of auditory nerve brainstem evoked responses to air- and bone-conducted stimuli.  


The auditory nerve brainstem evoked responses (ABRs) to bone conduction (BC) stimuli are longer in latency than those to air conduction (AC). In order to study the mechanism of this difference, ABR wave I was recorded in experimental animals in response to low intensity (0-20 dB above their threshold) logon stimuli delivered by BC and by using the same bone vibrator to generate the air-conducted stimulus. The BC stimuli were delivered to skull bone, and directly to the contents of the cranial cavity (brain and cerebrospinal fluid) through a craniotomy. ABR wave I in response to BC stimuli delivered to skull bone was significantly longer in latency than that to BC delivered on the brain, while there was no latency difference between AC stimuli and BC to the brain. Furthermore, the vibration (measured with an accelerometer) recorded on the brain during BC stimulation of skull bone was always delayed compared to that measured on the skull. Thus there is a delay in the transfer of vibratory energy from the skull bone to the underlying contents of the cranial cavity. From there, the delayed vibrations of the contents of the cranial cavity are transmitted to the inner ear. This is probably the mechanism of the longer latency BC response compared to the AC response. PMID:11591496

Sohmer, H; Freeman, S




EPA Science Inventory

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


Can subject-specific single-fibre electrically evoked auditory brainstem response data be predicted from a model?  


This article investigates whether prediction of subject-specific physiological data is viable through an individualised computational model of a cochlear implant. Subject-specific predictions could be particularly useful to assess and quantify the peripheral factors that cause inter-subject variations in perception. The results of such model predictions could potentially be translated to clinical application through optimisation of mapping parameters for individual users, since parameters that affect perception would be reflected in the model structure and parameters. A method to create a subject-specific computational model of a guinea pig with a cochlear implant is presented. The objectives of the study are to develop a method to construct subject-specific models considering translation of the method to in vivo human models and to assess the effectiveness of subject-specific models to predict peripheral neural excitation on subject level. Neural excitation patterns predicted by the model are compared with single-fibre electrically evoked auditory brainstem responses obtained from the inferior colliculus in the same animal. Results indicate that the model can predict threshold frequency location, spatial spread of bipolar and tripolar stimulation and electrode thresholds relative to one another where electrodes are located in different cochlear structures. Absolute thresholds and spatial spread using monopolar stimulation are not predicted accurately. Improvements to the model should address this. PMID:23021310

Malherbe, Tiaan K; Hanekom, Tania; Hanekom, Johan J



Evoked potential application to study of echolocation in cetaceans  

NASA Astrophysics Data System (ADS)

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.

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



Association of Hemoglobin levels and Brainstem Auditory Evoked Responses in Lead-Exposed Children  

PubMed Central

Objectives Decreased blood hemoglobin (HbB) levels and anemia have been associated with abnormal brainstem auditory evoked responses (BAER). Lead (Pb) exposure has also been associated with anemia and aberrant BAER. This study investigated the relationship between HbB level and BAER wave latency and amplitude in Pb-exposed Andean children. Design and methods Sixty-six children aged 2 to 15 years (mean age: 9.1; SD: 3.3) living in Pb-contaminated villages were screened for HbB levels, blood Pb (PbB) levels and BAER latencies and amplitudes. Results The mean HbB level observed in the study group was 11.9 g/dL (SD: 1.4; range: 8.6–14.8 g/dL). The mean HbB level corrected for altitude was 10.3 g/dL (SD: 1.4; range: 6.9–13.1 g/dL), and suggestive of anemia. The mean PbB level was 49.3 ?g/dL (SD: 30.1; range: 4.4–119.1 ?g/dL) and indicative of Pb poisoning. Spearman Rho correlation analyses revealed significant associations between the BAER absolute latencies and HbB level, indicating that as the HbB level decreased, the BAER wave latency increased. Children with low HbB levels (?11 g/dL) showed significantly prolonged absolute latencies of waves I, II, III, IV and V compared to the children with normal HbB levels. Although a significant relationship between HbB and BAER waves was observed, no significant associations between PbB level and BAER parameters were found. Conclusion Low hemoglobin levels may diminish auditory sensory-neural function, and is therefore an important variable to consider when assessing BAER in children with anemia and/or Pb exposure.

Counter, S. Allen; Buchanan, Leo H.; Ortega, Fernando



Use of evoked potentials in preterm neonates.  

PubMed Central

This paper has reviewed the techniques used for recording evoked potentials in the premature infant and the early developmental changes. The maturational changes in the evoked potentials, including morphological changes, and the very rapid latency changes within the first months of life, provide an invaluable means for assessing and monitoring development within the central nervous system. The maturational changes are such that normative values are requisite, and the norms must take into account both the infant's gestational age at birth as well as the postnatal age. These norms can then be used to aid in the assessment of gestational age, and whether there has or has not been normal maturational development, either in utero or during the postnatal preterm period. Evoked potentials are of increasing value clinically in preterm neonates, primarily because of the difficulty in obtaining reliable neurological evaluation of these infants. Median nerve SEPs may provide reliable information in preterm infants at risk of PVL, and when recorded in the second week of life, predict cerebral palsy. PTN SEPs seem to be even more reliable indicators of outcome, but the difficulty in obtaining them in preterm infants needs to be taken into consideration. Further study is needed in some areas, such as in apnoeic preterm babies clearly to establish the role that evoked potentials (in this case BAEPs) may have in understanding both the aetiology and the clinical course of this dysfunction. In other conditions, such as delayed intrauterine growth, that may lead to neurological sequelae, evoked potentials can provide objective CNS assessment. Evoked potentials may also prove useful in the monitoring of treatment modalities for preterm infants. The evoked potentials are a valuable adjunct in the assessment of preterm neonates and, as their value is recognised, we expect their use to increase.

Taylor, M. J.; Saliba, E.; Laugier, J.



A microcomputer-based system for auditory evoked potentials.  


We have been using a microprocessor/microcomputer-based system which affords flexibility in the recording of neuroaudiologic and neurophysiologic data. To date, we have used it to record auditory sensory and neural events. Data such as spontaneous oto-acoustic emissions, evoked oto-acoustic emissions, compound action potentials, and auditory brain-stem responses can be recorded, displayed and analysed. The system hardware is configured from commercially available and 'off-the-shelf' components. The software which directs stimulus generation, data recording, data display and analysis is all written in compiled BASIC or C. A hard-disk organizational scheme has also been developed to permit ease in categorizing, storing, and using in-house or commercially available systems, utility and applications software. PMID:2814325

Moore, E J; Rakerd, B; Robb, R C; Semela, J J; Hooks, W C



Short latency visual evoked potentials in man.  


Contrary to auditory and somatosensory evoked potentials, surface recorded visual evoked potentials which arise in subcortical neural elements have rarely been described. Considerable disagreement exists between the reports in the literature on such visual potentials. In this study, flash stimuli were used to evoke the potentials which were recorded from the skin overlying the infra-orbital ridge, outer canthus, middle of the forehead, vertex, mastoid ipsilateral to the stimulated eye and inion, using a non-cephalic reference. The potentials were amplified in a band which was chosen to omit slow retinal and cortical potentials, and to enhance activity which might include compound neural activity. Potentials were recorded from 9 subjects (13 eyes), and for each one the effects of eye position and stimulus intensity were studied. The results indicate that the series of components recorded within the first 100 msec following photic stimulation were volume-conducted activity generated by a subset of the visual system which is activated by luminosity changes. The generators of the first 4 or 5 components seem to be situated within the retina, the subsequent components seem to be generated in the optic nerve or tracts, and the later components may be thalamo-cortical in origin. These potentials may complement pattern evoked potentials in a more accurate definition of sites of lesions along the visual pathway. PMID:6177518

Pratt, H; Bleich, N; Berliner, E



Evoked Potentials in Acute Head Injured Patients with MRI-Detected Intracerebral Lesions  

Microsoft Academic Search

Summary.\\u000a Summary.  \\u000a \\u000a \\u000a Background:   Magnetic resonance imaging (MRI) allows precise detection of intracranial lesions in head injured patients. We compared intracranial\\u000a lesions detected in MRI to somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) concerning\\u000a their prognostic value.\\u000a \\u000a \\u000a \\u000a Methods:   Thirty patients with traumatic brain injury and prolonged recovery were studied. Size, side and number of 474 intra- and\\u000a extraparenchymal

F. Soldner; B. M. Hölper; L. Chone ´; T. Wallenfang



Visual Evoked Potential Changes in Hyperbaric Atmospheres.  

National Technical Information Service (NTIS)

The visual evoked potential (VEP) in chloralose-anesthetized cats decreased in amplitude as a function of increasing pressure. This was true for compression with pO2 = 200 or 1,000 mm Hg. Maintained pressure while changing pO2 from p)2 from 200 to 1,000 m...

C. R. Larson D. Sutton E. M. Taylor J. D. Burns



Modeling the vestibular evoked myogenic potential  

Microsoft Academic Search

Measuring the vestibular evoked myogenic potential (VEMP) promises to become a routine method for assessing vestibular function, although the technique is not yet standardized. To overcome the problem that the VEMP amplitude depends not only on the inhibition triggered by the acoustic stimulation of the vestibular end organs in the inner ear, but also on the tone of the muscle

Bernd Lütkenhöner; Wolfgang Stoll; Türker Basel



Repetitive magnetic stimulation and motor evoked potentials  

Microsoft Academic Search

The aim of the study was to evaluate the effect of varying stimulus rates of repetitive transcranial magnetic stimulation (RTMS) on the motor evoked potentials (MEPs) recorded from the right abductor pollicis brevis muscle (APB). Thirteen normals were included. Stimuli were applied to the cortex and to the median nerve at the wrist. The cortical stimuli were applied without and

Poul Jennum; Henrik Winkel; Anders Fuglsang-Frederiksen



Motor-evoked potentials: unusual findings  

Microsoft Academic Search

Objective: The aims of this study were to present rare findings of motor evoked potentials (MEPs) in 3 patients with spastic paraparesis and to show that careful interpretation is indispensable in experiments done with very high intensity stimulation.Methods: The conduction along several segments of the descending tracts was studied by our previously published method in 3 patients with spastic paraparesis.Results:

Yoshikazu Ugawa; Ichiro Kanazawa



Kallmann's syndrome and chemosensory evoked potentials  

Microsoft Academic Search

Kallmann's syndrome is generally assessed by history and subjective tests of olfactory function. In this study three patients suffering from Kallmann's syndrome were investigated with more objective techniques, including the recording of chemosensory evoked potentials (CSEPs). After testing olfactory function by means of a simple odor identification test, anosmia was confirmed in only one patient, since the other two patients

T. Hummel; H. Pietsch; G. Kobal



Somatosensory evoked potentials to median nerve stimulation in meningomyelocele: what is occurring in the hindbrain and its connections during growth?  

Microsoft Academic Search

Twenty patients with meningomyelocele (MMC) and shunted hydrocephalus, ranging in age from 3 to 23 years old, underwent serial recording of short-latency somatosensory evoked potentials (SEPs) to median nerve stimulation, on the basis of which to assess the evolution of dysfunction in the brainstem and its connections (cervical spinal cord, cervical nerve roots, lower cranial nerves). Eighteen patients had Chiari

Toshihiko Nishimura; Koreaki Mori



Click-evoked myogenic potentials recorded on alert guinea pigs.  


The aim of this study was to establish an animal model of acoustically evoked vestibulo-collic reflex using guinea pigs. A special clamp was applied to restrain the head and body of the guinea pigs, but leaving its four legs free. Each animal underwent vestibular evoked myogenic potential (VEMP) and caloric tests using clip electrode method without general anesthesia or decerebrate surgery. The response rates for the myogenic potentials on the neck of guinea pigs using 100, 90, 80 and 70 dB monaural acoustic stimulation with unilateral recording were 100%, 62%, 50% and 0%, respectively. The mean latencies of the positive and negative peaks for the myogenic potentials were 7.24+/-0.49 and 9.15+/-0.47 ms, 7.09+/-0.43 and 9.28+/-0.42 ms, as well as 7.03+/-0.59 and 9.14+/-0.56 ms, when elicited by 100, 90 and 80 dB acoustic stimulation, respectively. The median (minimum-maximum) peak-to-peak amplitudes were 11.93 (6.14-16.86), 10.99 (5.28-19.40), and 11.17 (5.02-20.72) microV, when elicited by 100, 90 and 80 dB acoustic stimulation, respectively. We found no significant relationship between the stimulus intensity and the mean latencies or peak-to-peak amplitude of the myogenic potentials in guinea pigs. For those treated with gentamicin unilaterally, all guinea pigs showed absent caloric responses on the lesion side, and absent myogenic potentials on the neck when using ipsi-lesional acoustic stimulation, while the hearing was preserved. Hence, the use of gentamicin-treated animals, along with normal controls and auditory brainstem responses, results in convincing results that the recorded myogenic potentials are in fact of vestibular origin. PMID:15953537

Yang, Ting-Hua; Young, Yi-Ho



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

PubMed Central

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

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



Evoked Potentials to Evaluate Mechanisms of Peripheral Nerve Repair.  

National Technical Information Service (NTIS)

The goals of this peripheral nerve project include development of a neurophysiologic technique termed 'evoked potentials' for, not only objective, but also relatively early evaluation of injured nerves. Evoked potentials as well as electromyography are us...

D. G. Kline E. R. Hackett P. A. McGarry S. Liles G. D. Davis



Brainstem stimulation during sleep evokes abnormal rhythmic activity in thalamic neurons in feline penicillin epilepsy  

Microsoft Academic Search

Some periods in the sleep-waking cycle are more seizure prone than others. In absence epilepsy, transition periods between nonrapid-eye-movement (nonREM) sleep and waking or REM sleep can be more seizure prone that stable states. One feature of transition periods that is hypothesized to promote seizure activity is the presence of coincident activity in ascending brainstem reticular formation (RF) arousal systems

Ronald Szymusiak; Margaret N. Shouse; Dennis McGinty



Developments for recording lumbosacral evoked potentials.  


Detailed measurement of lumbosacral evoked potentials is usually only feasible using sophisticated, multichannel neurophysiological equipment. This paper describes the recording technique, and the additional equipment developed for use with a high-quality two-channel recording system, the Dantec Neuromatic 2000M, to facilitate the routine measurement of these potentials. The characteristic feature is a microprocessor based control unit, which allows switching of multiple input channels prior to preamplification and detects the electrocardiogram to trigger the stimulus with a variable time delay. PMID:3244152

Lucas, M; Wild, P



Brainstem Auditory Evoked Responses in Man. 1: Effect of Stimulus Rise-Fall Time and Duration.  

National Technical Information Service (NTIS)

Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and ...

K. Hecox N. Squires R. Galambos



Inhibitory effect of capsaicin evoked trigeminal pain on warmth sensation and warmth evoked potentials  

Microsoft Academic Search

The aim of the study was to evaluate the effect of tonic pain evoked by topical application of capsaicin on the somatosensory sensation of warmth. The warmth pathways were studied in ten healthy subjects by recording the scalp potentials evoked by non-painful warm laser stimuli delivered on both the right and left perioral region (warmth C-fiber related laser-evoked potentials (C-LEPs)).

Massimiliano Valeriani; Michele Tinazzi; Domenica Le Pera; Domenico Restuccia; Liala De Armas; Toni Maiese; Pietro Tonali; Lars Arendt-Nielsen



[Motor evoked potentials in thoracoabdominal aortic surgery].  


Thoracoabdominal aortic disease (aneurysm or dissection) has increased in recent decades. Surgery is the curative treatment but is associated to high perioperative morbidity and mortality risks. Paraplegia is one of the most severe complications, whose incidence has decreased significantly with the implementation of spinal cord protection strategies. No single method or combination of methods has proven to be fully effective in preventing paraplegia. This review is intended to analyse the scientific evidence available on the role of intraoperative monitoring with motor evoked potentials in the neurological outcome of patients undergoing thoracoabdominal aortic surgery. An online search (PubMed) was conducted. Relevant references were selected and reviewed. Intraoperative monitoring with motor evoked potentials (MEP) allows early detection of ischemic events and a targeted intervention to prevent the development of spinal cord injury, significantly reducing the incidence of postoperative paraplegia. MEP monitoring may undergo several intraoperative interferences which may compromise their interpretation. Neuromuscular blockade is the main limiting factor of anesthetic origin. It is essential to strike a balance between monitoring conditions and surgical and anesthetic needs as well as to evaluate the risks and benefits of the technique for each patient. MEP monitoring improves neurological outcome when integrated in a multidisciplinary strategy which must include multiple protective mechanisms that should be tailored to each hospital reality. PMID:24490197

Magro, Cátia; Nora, David; Marques, Miguel; Alves, Angela Garcia



Long-Term Evolution of Brainstem Electrical Evoked Responses to Sound after Restricted Ablation of the Auditory Cortex  

PubMed Central

Introduction This study aimed to assess the top-down control of sound processing in the auditory brainstem of rats. Short latency evoked responses were analyzed after unilateral or bilateral ablation of auditory cortex. This experimental paradigm was also used towards analyzing the long-term evolution of post-lesion plasticity in the auditory system and its ability to self-repair. Method Auditory cortex lesions were performed in rats by stereotactically guided fine-needle aspiration of the cerebrocortical surface. Auditory Brainstem Responses (ABR) were recorded at post-surgery day (PSD) 1, 7, 15 and 30. Recordings were performed under closed-field conditions, using click trains at different sound intensity levels, followed by statistical analysis of threshold values and ABR amplitude and latency variables. Subsequently, brains were sectioned and immunostained for GAD and parvalbumin to assess the location and extent of lesions accurately. Results Alterations in ABR variables depended on the type of lesion and post-surgery time of ABR recordings. Accordingly, bilateral ablations caused a statistically significant increase in thresholds at PSD1 and 7 and a decrease in waves amplitudes at PSD1 that recover at PSD7. No effects on latency were noted at PSD1 and 7, whilst recordings at PSD15 and 30 showed statistically significant decreases in latency. Conversely, unilateral ablations had no effect on auditory thresholds or latencies, while wave amplitudes only decreased at PSD1 strictly in the ipsilateral ear. Conclusion Post-lesion plasticity in the auditory system acts in two time periods: short-term period of decreased sound sensitivity (until PSD7), most likely resulting from axonal degeneration; and a long-term period (up to PSD7), with changes in latency responses and recovery of thresholds and amplitudes values. The cerebral cortex may have a net positive gain on the auditory pathway response to sound.

Lamas, Veronica; Alvarado, Juan C.; Carro, Juan; Merchan, Miguel A.




EPA Science Inventory

Stimultaneous recording from 21 electrode sites in a 4x4 mm area over the posterior cortex was used to determine the surface distribution of all major peaks which constitute flash evoked potentials (FEPs) and pattern reversal evoked potentials (PREPs) in hooded rats. Topographica...


Reducing blanking artifact in electrically evoked compound action potentials.  


The main source of distortion in the recording of the electrically evoked compound action potentials is the stimulus artifact. The popular hardware blanking technique tends to reduce this artifact, but generates a blanking artifact as a consequence of the transient state in the amplifier. In this paper we propose two techniques to deal with the blanking artifact. The proposed techniques are combined with conventional and generalized alternating stimulation in order to reduce both stimulus and blanking artifacts in the recording of the evoked potentials. A comparison over 126 evoked potential recordings reveals that the proposed blanking artifact reduction methods improve the quality of electrically evoked compound action potential recordings. PMID:19833406

Alvarez, Isaac; de la Torre, Angel; Sainz, Manuel; Roldán, Cristina



A comparison of transient-evoked otoacoustic emissions and automated auditory brainstem responses for pre-discharge neonatal hearing screening.  


The aim of this study was to compare two hearing-screening methods in well newborn infants within the postnatal ward environment prior to discharge. Eighty-one newborn infants underwent one-step hearing screening by measurement of automated auditory brainstem responses (aABRs), using the ALGO-3 screener. These were compared with a further cohort of 81 neonates who underwent two-step screening using transient-evoked otoacoustic emissions (TEOAEs) followed by aABR. The pass rate was 78/81 (96.3%) for the one-step screen, 74/81 (91.4%) for the two-step screen, and 54/81 (66.7%) for TEOAE alone. There was no significant difference between cohorts in time required to complete the screening protocol. We conclude that pre-discharge hearing screening of newborn infants on the postnatal ward is feasible and acceptable. Use of TEOAE alone for pre-discharge screening is associated with an excessively high false-positive rate. At our institution, one-step screening resulted in a lower referral rate compared with a two-step approach. The performance of aABR screening may be affected by prior TEOAE screening. PMID:14658852

Clarke, Paul; Iqbal, Mohammed; Mitchell, Simon



Methodological factors involved in neonatal screening using transient-evoked otoacoustic emissions and automated auditory brainstem response testing.  


The methodological factors involved in screening neonates for hearing loss, using transient-evoked otoacoustic emissions (TEOAEs) and automated auditory brainstem responses, have been evaluated from a large sample of neonates. The risk factors, commonly used to select babies for a targeted screen, have very little correlation with failing TEOAE testing. The parameters used to determine passing or failing the TEOAE test and the false alarm rate change markedly with age in the first few days of life as, of course, did the percentage of babies who failed the test. The stimulus level used was the default setting for the Otodynamics equipment but the stimulus level measured in the ear canal decreased over the first 140 h of life. It is thought that this reflects the impedance changes in outer and middle ears and possible changes in middle ear dynamics. The methodological variables investigated here can illuminate some of the differences in previous reports of neonatal screening, in particular the reported hit and false alarm rates. PMID:12948603

Thornton, A Roger D; Kimm, Lindsay; Kennedy, Colin R



Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential  

NASA Astrophysics Data System (ADS)

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.

Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai



Anterior spinal cord injury with preserved neurogenic ‘motor’ evoked potentials  

Microsoft Academic Search

Objective: To describe two cases in which intraoperative monitoring of neurogenic ‘motor’ evoked potentials (NMEPs) did not identify a spinal cord injury that resulted in paraplegia.Methods: Bilateral tibial nerve somatosensory evoked potential (SEP) and NMEP testing was performed in two patients during spinal deformity corrective surgery using standard stimulation and recording parameters. These potentials were obtained repetitively throughout the primary

Robert E Minahan; Jehuda P Sepkuty; Ronald P Lesser; Paul D Sponseller; John P Kostuik



Modeling the vestibular evoked myogenic potential.  


Measuring the vestibular evoked myogenic potential (VEMP) promises to become a routine method for assessing vestibular function, although the technique is not yet standardized. To overcome the problem that the VEMP amplitude depends not only on the inhibition triggered by the acoustic stimulation of the vestibular end organs in the inner ear, but also on the tone of the muscle from which the potential is recorded, the VEMP is often normalized by dividing through a measure of the electromyogram (EMG) activity. The underlying idea is that VEMP amplitude and EMG activity are proportional. But this would imply that the muscle tone is irrelevant for a successful VEMP recording, contradicting experimental evidence. Here, an analytical model is presented that allows to resolve the contradiction. The EMG is modeled as the sum of motor unit action potentials (MUAPs). A brief inhibition can be characterized by its equivalent rectangular duration (ERD), irrespective of the actual time course of the inhibition. The VEMP resembles a polarity-inverted MUAP under such circumstances. Its amplitude is proportional to both the ERD and the MUAP rate. The EMG activity, by contrast, is proportional to the square root of the MUAP rate. Thus, the normalized VEMP still depends on the muscle tone. To avoid confounding effects of the muscle tone, the standard deviation of the EMG could be considered. But the inhibition effect on the standard deviation is small so that the measuring time would have to be much longer than usual today. PMID:19896953

Lütkenhöner, Bernd; Stoll, Wolfgang; Basel, Türker



Laser evoked potentials in amyotrophic lateral sclerosis.  


The pathophysiological mechanism of the pain in ALS is still unclear. The aim of the study was to evaluate the laser evoked potentials (LEPs) in ALS patients in relation to their clinical features. Twenty-four ALS patients were selected. Pain features were assessed and their intensity was measured by a 0-10 VAS. LEPs were recorded in all patients and in 23 healthy subjects. The dorsum of both hands was stimulated, at laser stimuli intensity of 7.5 W, with 10s inter-stimulus interval and 25 ms duration. Four electrodes were placed at Cz, T3, T4 and Fz positions, with the reference electrode at the nasion; T3 and T4 electrodes were referred off-line to Fz, in order to detect the N1 component. Latencies of N2, P2 and N1 waves were significantly higher in ALS than in controls. N1 amplitude was significantly increased in ALS patients compared to controls, with a similar trend for the N2-P2 complex. No correlation was found between LEP abnormalities, pain intensity and clinical features. A degeneration of subcortical structures may subtend a delay in the afferent input to the nociceptive cortex in ALS. On the other hand, an increase of pain processing at the cortical level may derive from a potential sensory compensation to motor cortex dysfunction. PMID:19836030

Simone, Isabella Laura; Tortelli, Rosanna; Samarelli, Vito; D'Errico, Eustachio; Sardaro, Michele; Difruscolo, Olimpia; Calabrese, Rita; Francesco, Vito De Vito; Livrea, Paolo; de Tommaso, Marina



Deconvolution of the vestibular evoked myogenic potential.  


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

Lütkenhöner, Bernd; Basel, Türker



Motor and somatosensory evoked potentials in hereditary spastic paraplegia  

Microsoft Academic Search

Motor evoked potentials (MEPs) from the arms and legs to transcranial stimulation of the motor cortex and somatosensory evoked potentials (SSEPs) from stimulation of the nerves of the arms and legs, were recorded in 11 patients with hereditary spastic paraplegia. Electrophysiological abnormalities were found to be distributed differently among the systems examined; the longer the pathway, the higher the incidence

L Pelosi; B Lanzillo; A Perretti; L Santoro; L Blumhardt; G Caruso



Pudendal nerve somatosensory evoked potentials in probable multiple sclerosis  

Microsoft Academic Search

Bladder dysfunctions are often observed in patients with multiple sclerosis (MS). In order to evaluate their sensitivity in detecting abnormalities in bladder central control pathways, pudendal nerve somatosensory evoked potentials (pSEPs) were recorded in 16 patients with clinically probable MS: six were affected by retention or urge incontinence, and ten were asymptomatic. Conventional visual, auditory and somatosensory evoked potentials were

G. F. Sau; I. Aiello; S. Siracusano; M. Belgrano; M. Pastorino; P. Balsamo; I. Magnano; G. Rosati



Multixnodality Evoked Potential Findings in Infants With Congenital Heart Defects  

Microsoft Academic Search

Evoked potentials are sensitive prognostic tools in young infants at risk for developmental disability. The objective of this prospective study was to determine whether infants with congenital heart defects demonstrate evoked potential abnormalities prior to or following open heart surgery, and to examine the association between these abnormalities and developmental status 1 year following surgery. A consecutive series of newborns

Catherine Limperopoulos; Annette Majnemer; Bernard Rosenblatt; Michael Shevell; Charles Rohlicek; Christo Tchervenkov



Auditory evoked potential measurements in elasmobranchs  

NASA Astrophysics Data System (ADS)

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.

Casper, Brandon; Mann, David



Finding physiological responses in vestibular evoked potentials.  


Vestibular prostheses are regarded as a promising tool to restore lost sensation in patients with vestibular disorders. These prostheses often electrically stimulate the vestibular nerve and stimulation efficacy is evaluated by measuring the vestibulo-ocular reflex (VOR). However, eye movement recording as intuitive metric of vestibular functionality is difficult to obtain outside the laboratory environment, and hence not available as an error signal in a closed-loop prosthesis. Recently we investigated vestibular evoked potentials (VEPs) by stimulating and recording in the same semicircular canal of a guinea pig. Here we studied the correlation between VOR and one region of VEP. We further analyzed a second portion of VEP, where vestibular nerve activity should occur using rectified bin integration (RBI). To this end, stimulation artifact was significantly reduced by hardware and software approaches. We found a high VEP-VOR correlation (R-squared=0.86), suggesting that VEP could substitute VOR as metric of vestibular function. Differences between below and above vestibular threshold stimulation were seen for the second portion of VEP. Further investigations are required to determine the specific parts of VEP that accurately represents vestibular function(s). PMID:22254790

Nguyen, T A K; Kogler, V; DiGiovanna, J; Micera, S



Conventional and cross-correlation brain-stem auditory evoked responses in the white leghorn chick: rate manipulations  

NASA Technical Reports Server (NTRS)

Rate-dependent changes in the chick brain-stem auditory evoked response (BAER) using conventional averaging and a cross-correlation technique were investigated. Five 15- to 19-day-old white leghorn chicks were anesthetized with Chloropent. In each chick, the left ear was acoustically stimulated. Electrical pulses of 0.1-ms duration were shaped, attenuated, and passed through a current driver to an Etymotic ER-2 which was sealed in the ear canal. Electrical activity from stainless-steel electrodes was amplified, filtered (300-3000 Hz) and digitized at 20 kHz. Click levels included 70 and 90 dB peSPL. In each animal, conventional BAERs were obtained at rates ranging from 5 to 90 Hz. BAERs were also obtained using a cross-correlation technique involving pseudorandom pulse sequences called maximum length sequences (MLSs). The minimum time between pulses, called the minimum pulse interval (MPI), ranged from 0.5 to 6 ms. Two BAERs were obtained for each condition. Dependent variables included the latency and amplitude of the cochlear microphonic (CM), wave 2 and wave 3. BAERs were observed in all chicks, for all level by rate combinations for both conventional and MLS BAERs. There was no effect of click level or rate on the latency of the CM. The latency of waves 2 and 3 increased with decreasing click level and increasing rate. CM amplitude decreased with decreasing click level, but was not influenced by click rate for the 70 dB peSPL condition. For the 90 dB peSPL click, CM amplitude was uninfluenced by click rate for conventional averaging. For MLS BAERs, CM amplitude was similar to conventional averaging for longer MPIs.(ABSTRACT TRUNCATED AT 250 WORDS).

Burkard, R.; Jones, S.; Jones, T.



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

PubMed Central

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.

Leite, Renata Aparecida; Wertzner, Haydee Fiszbein; Goncalves, Isabela Crivellaro; Magliaro, Fernanda Cristina Leite; Matas, Carla Gentile



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


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

Finneran, James J



Tone-evoked brainstem responses and auditory steady state responses to 40hz and 80hz amplitude modulated stimuli with different frequencies — a comparative study  

Microsoft Academic Search

Abstract  Tone burst evoked auditory brainstem responses and auditory steady state responses with 40 or > 80 Hz modulation can be used\\u000a to determine frequency specific threshold.\\u000a \\u000a \\u000a \\u000a Aim  The present study was taken up to check for the efficacy of estimating hearing thresholds by tone burst ABR and ASSR. The\\u000a frequency effect (low, mid and high) on estimating the threshold was also

Kaushlendra Kumar; Sujeet Kumar Sinha; Jayashree S. Bhat



Click-evoked potentials on the neck of the guinea pig.  


Vestibulocollic reflex in humans is called vestibular evoked myogenic potential. To try to establish an animal model of the acoustically evoked vestibulocollic reflex, 18 guinea pigs were used in this study. Eight of the 18 guinea pigs received intramuscular injection of amikacin for 18 days (450 mg/kg/day) before recording to destroy the cochlea pharmacologically. Under general anesthesia with intraperitoneal injection of pentobarbital sodium (40 mg/kg body weight), auditory brainstem responses (ABRs) were recorded. Then potentials on the neck evoked by loud clicks were recorded on the pre-vertebral muscle or on the spinal cord at the level of third cervical vertebral bone using a silver-ball electrode. As a result, a negative peak (NP) with a latency of 6 approximately 8 ms was observed on the neck muscle or on the spinal cord in the control group. The thresholds of the NP were 90-100 dB above those of ABRs. The NP was also observed in the amikacin-administered group using clicks with the same intensity as that for the control group, while the ABR thresholds were highly elevated. These results are in agreement with a vestibular origin of the NP potential. PMID:12031524

Matsuzaki, Masaki; Murofushi, Toshihisa



Transient Evoked Potential in a Critical Event Detection Task.  

National Technical Information Service (NTIS)

An experiment was designed to investigate late positive components of the transient evoked potential elicited by detection of a perceptually complex critical event. Areas of investigation included spatial distribution, motor response effects, stimulus dur...

S. A. Huddleson



Use of Sensory Evoked Potentials in Neurotoxicity Testing of Workers,  

National Technical Information Service (NTIS)

Electrophysiological measures appropriate for use in neurotoxicity testing of workers are briefly reviewed. These measures include auditory, visual and somatosensory evoked potentials. Relevant human studies are reviewed. Selection criteria, strengths and...

D. A. Otto



Enhanced neuronal excitability in adult rat brainstem causes widespread repetitive brainstem depolarizations with cardiovascular consequences  

PubMed Central

The brainstem of the adult rat is relatively resistant to spreading depolarization (SD) but after enhancement of excitability SD can be evoked by local application of KCl. In the present experiments, we observed that the enhanced excitability even triggers prolonged periods of repetitive depolarizations (RDs), which elicit significant cardiovascular changes. In contrast to KCl-evoked SDs with amplitudes of ?24?mV and spreading velocity of 4?mm/min, spontaneous RDs had amplitudes of 7 to 12?mV, propagated up to 30 times faster than KCl-evoked SDs, and depolarized larger brainstem areas including the contralateral side. Similarly as SD, RDs depended on glutamatergic neurotransmission and were blocked by MK-801 or by the calcium channel blocker agatoxin. They depended on sodium channels and were blocked by tetrodotoxin. Functionally, the invasion of RDs into the spinal trigeminal and other nuclei evoked bursts of action potentials, indicating that specific neuronal systems are affected. In fact, during episodes of RDs the blood pressure and the local blood flow at the surface of the brainstem and the cortex increased substantially. Brainstem RDs did not propagate into the cerebral cortex. We propose to consider brainstem RPs as a pathophysiological mechanism whose significance for brainstem disease states should be further explored.

Richter, Frank; Bauer, Reinhard; Ebersberger, Andrea; Lehmenkuhler, Alfred; Schaible, Hans-Georg



Vestibular receptors contribute to cortical auditory evoked potentials.  


Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin. PMID:24321822

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



Suboccipital craniotomy for Chiari I results in evoked potential conduction changes  

PubMed Central

Background: Management of Chiari I is controversial, in part because there is no widely used quantitative measurement of decompression. It has been demonstrated that brainstem auditory evoked responses (BAER) and somatosensory evoked potentials (SSEP) have decreased conduction latencies after wide craniectomy. We analyzed these parameters in a suboccipital craniectomy/craniotomy procedure. Methods: Thirteen consecutive patients underwent suboccipital decompression for treatment of symptomatic Chiari I. Craniectomy was restricted to the inferior aspect of the nuchal line, and in most cases the bone flap was replaced. Neuronal conduction was monitored continuously with median nerve somatosensory evoked potentials (M-SEP), posterior tibial nerve somatosensory evoked potentials (T-SEP), BAER, or a combination. The M-SEP N20, T-SEP P37, and BAER V latencies were recorded at four milestones – preoperatively, following craniotomy, following durotomy, and following closure. Results: Five males and eight females, with average age of 9 years, were studied. Clinical improvement was noted in all 13 patients. M-SEP N20 latency decreased from a mean of 18.55 at baseline to 17.75 ms after craniotomy (P = 0.01); to 17.06 ms after durotomy (P = 0.01); and to 16.68 ms after closing (P = 0.02). T-SEP P37 latency did not change significantly. BAER V latency decreased from a mean of 6.25 ms at baseline to 6.14 ms after craniotomy (P = 0.04); to 5.98 ms after durotomy (P = 0.01); and to 5.95 ms after closing (P = 0.45). Conclusion: Significant improvements in conduction followed both craniectomy and durotomy. Bone replacement did not affect these results.

Chen, Jason A.; Coutin-Churchman, Pedro E.; Nuwer, Marc R.; Lazareff, Jorge A.



Ocular Vestibular Evoked Myogenic Potential Using Different Test Stimuli  

PubMed Central

Aim. Ocular Evoked Myogenic Potential (oVEMP) are short latency potentials evoked by higher acoustic stimulation. In this study, we aimed at comparing the click, 500?Hz mixed modulated, and 500?Hz short duration tone burst stimuli using oVEMP. Material. Click, 500?Hz mixed modulated and 500?Hz short duration tone burst stimuli were used for the study. Method. Conventional sampling and conveneint study design were used. Sixty healthy subjects underwent contralateral oVEMP testing maintaining 30 degrees upward gaze. Single channel electrode montage was applied to record oVEMP response. Results. On statistical analysis the three stimuli evoked equal response rates (100%), and when latency of n1 and p1 and peak-peak amplitude were compared, the click evoked showed significantly early latency and lower peak-peak amplitude than the 500?Hz stimuli. Five hundred Hz stimuli did not show significant difference in latency and peak-peak amplitude of n1-p1. Discussion. Thus, 500?Hz stimuli can evoke better latency and peak-peak amplitude. oVEMP has good clinical significance in diagnosing subjects with vestibular dysfunction. To add to the sensitivity of the oVEMP test, 500?Hz stimuli may also be used as it can evoke better oVEMP responses in clinical population with good morphology.

Deepak, Dessai Teja; Bhat, Jayashree S.; Kumar, Kaushlendra



Transient deafferentation in humans induces rapid modulation of primary sensory cortex not associated with subcortical changes: a somatosensory evoked potential study  

Microsoft Academic Search

Human somatosensory cortex (S1) is capable of rapid modification after temporary peripheral deafferentation but it is not known whether subcortical changes contribute to this modulation. We recorded spinal, brainstem and cortical somatosensory evoked potentials (SEPs) to median nerve stimulation following anaesthetic block of the ipsilateral ulnar nerve. Spinal N13 and subcortical P14, N18 potentials remained unchanged during the experiment. N20\\/P20,

M Tinazzi; G Zanette; A Polo; D Volpato; P Manganotti; C Bonato; R Testoni; A Fiaschi



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

NASA Astrophysics Data System (ADS)

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.

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



Prevention of spinal cord injury with time-frequency analysis of evoked potentials: an experimental study  

Microsoft Academic Search

OBJECTIVESTo verify the applicability and validity of time-frequency analysis (TFA) of evoked potential (EP) signals in detecting the integrity of spinal cord function and preventing spinal cord injury.METHODSThe spinal cord was simulated during surgery in 20 mature rats by mechanically damaging the spinal cord. Cortical somatosensory evoked potential (CSEP), spinal somatosensory evoked potential (SSEP), cortical motor evoked potential (CMEP), and

Yong Hu




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...


Sensory, cognitive and motor assessment of children with poor academic performance: an auditory evoked potential study.  


The present study aims to evaluate the auditory sensory process in the brainstem, thalamocortical and cortical areas by using auditory evoked potentials [auditory brainstem response (ABR), mid latency response (MLR) and slow vertex response (SVR)], cognitive functions by P300 and motor response by reaction time in children with poor academic performance. Thirty children between 6-12 years of age were selected as subjects on the basis of poor academic school records. While thirty children with good academic performance served as controls. The recordings were done using a computerized evoked potential recorder by 10-20 electrode placement system. There was no difference in the anthropometric parameters and IQ of the two groups. There was a significant increase in latency of waves II, III, IV and V, and Inter-peak latency I-V of ABR in poor performer females. All the component waves of MLR and SVR showed increased latency in the subjects but could not reach the level of significance. There was a significant increase in latencies of P300 at Cz and Pz electrode positions with no change in amplitude in poor performer females. The reaction time was also increased in the poor performer females as compared to the controls. The latencies of all the waves of ABR, P300 and reaction time are also increased in male poor performers as compared to male controls but could not reach the level of significance. The conduction of impulses is slower in pontine and midbrain auditory pathway along with inefficient cortical processing of task relevant stimuli and motor response in female children having poor academic performance. PMID:21409863

Khaliq, Farah; Alam, Kaushal Kumar; Vaney, Neelam; Singh, T B



Evoked potential measurement and analysis on a small laboratory computer.  


A program is described for the collection and subsequent analysis of somatosensory evoked potentials using a LINC-8 computer. The program allows simple evoked-potentials analysis in centers where a small laboratory computer may be available but sophisticated instrumentation such as a computer of average transients is not available. This program provides an efficient method of easily obtaining information concerning the conduction pathways of the nervous system as well as the cerebral function; the program can be implemented on small laboratory computers which most hospitals currently own, without the associated cost or complexity of additional hardware in the laboratory. Combining utilization of a small laboratory computer with an easily programmable method provides an approach for evoked potential analysis which is well within the financial and technical scope of most neurophysiology laboratories. PMID:755603

Cohen, B A; Myklebust, J



Vestibular evoked myogenic potentials: optimal stimulation and clinical application  

Microsoft Academic Search

Summary  By easily stimulating the ear with loud sound and recording on tonically contracted neck muscles, vestibular evoked myogenic potential (VEMP) test can reflect inner ear function other than the cochlea and semicircular canal. This expands the test battery for clinicians to explore saccular disease, adding a potential usefulness to the sacculo-collic reflex. The ideal stimulation mode for VEMPs is as

Yi-Ho Young



Visual and somatosensory evoked cortical potentials in multiple sclerosis.  

PubMed Central

The diagnostic value of the pattern reversal evoked cortical potential (VEP) and the somatosensory evoked cortical potential (SEP) has been compared in 50 patients with established or suspected multiple sclerosis. A prolonged latency of VEP was found in 96% of definite cases of multiple sclerosis, 58% of probable cases, and 20% of possible cases. A prolonged latency of SEP by stimulation of median or peroneal nerves or both was found in 86% of definite cases of multiple sclerosis, 83% of probable cases, and 50% of possibe cases. When combining the results of all three tests the diagnostic yield increased to 100%, 92%, and 50%, respectively.

Trojaborg, W; Petersen, E



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


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 could be carried out. Despite these difficulties, evoked potential monitoring seems useful. We believe, however, that it is not routinely used in operating rooms at present because alterations of the responses can be due to different causes; for the neurosurgeon, the problem as to which interdependent degrees of alteration in evoked potentials are related to neuronal disturbances remains unsolved. PMID:3592205

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



[Neurophysiological evaluation using multimodal sensory evoked potentials in patients in coma: general aspects].  


Noninvasive sensory evoked potentials (SEP) performed at bedside in the Intensive Care Unit for patients in coma can be helpful in establishing both a diagnosis and a prognosis. Based on a more than 6-year experience on this subject, the authors discuss general aspects concerning these EP, their probable known generators, and propose a classification depicting different aspects observed for flash visual EP (F-VEP), brainstem auditory EP (BAEP), and median nerve somato-sensory EP (SSEP). Isolated, SSEP shows the best diagnostic and prognostic performance. Nevertheless, the authors consider that multimodality SEP are even better than any isolated EP study; cross-correlating information generated through a horizontal (F-VEP), a vertical (SSEP), and a pathway focusing brainstem in greater detail (BAEP) allows the neurophysiological establishment of the level of lesion in the CNS from a better perspective; besides, SEP can help setting the diagnosis of brain (encephalic) death, and the diagnosis of particular problems concerning each pathway. Notwithstanding, most important is prognosis definition, and the findings are summarized. Abnormal BAEP implies bad prognosis, as would be expected considering the severity of a brainstem lesion; on the other hand, a normal BAEP per se does not allow a precise definition, resting on other EP the role prognosis characterization. SSEP if bilaterally normal or only mildly abnormal imply good prognosis; bilateral absence of SSEP thalamo-cortical components has always carried a bad prognosis, since younger patients may at best evolve into a persistent vegetative state; SSEP intermediary results are more often accompanied by variable evolution. FVEP results parallel those of SSEP. PMID:2264787

Luccas, F J; Lopes, J A; Plastino, F R; Knobel, E



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


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

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



On hemispheric differences in evoked potentials to speech stimuli  

NASA Technical Reports Server (NTRS)

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.

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



Motor evoked potentials of the respiratory muscles in tetraplegic patients  

Microsoft Academic Search

We studied the respiratory muscles with magnetic transcranial stimulation (TCS) in four spinal cord injured (SCI) patients as compared to age-matched controls from a database of 40 healthy subjects. These SCI patients all had spinal cord lesions above C6 level with a clinically incomplete tetraplegia. One patient was artificially ventilated. Motor evoked potentials (MEPs) were recorded from the diaphragm, the

Mark A Lissens; Guy G Vanderstraeten



Somatosensory evoked potentials in adults with cortical dysgenesis and epilepsy  

Microsoft Academic Search

Cortical dysgenesis (CD) is a well-recognised cause of epilepsy, but its functional anatomy is not fully understood. We recorded cortical somatosensory evoked potentials (SEPs) in 13 adult patients with epilepsy and various CDs excluding diffuse gyral malformations as diagnosed by MRI. The CD involved the perirolandic\\/perisylvian region in 7 patients. Six patients had neurological signs but only 3 had sensory

A. A Raymond; S. J Jones; D. R Fish; J Stewart; J. M Stevens



Real-Time Detection of Steady-State Evoked Potentials.  

National Technical Information Service (NTIS)

In order to use the visual evoked potential as a real-time monitor of the state of the visual system, a monitoring technique was developed to maximize the signal-to-noise (S/N) ratio. System response parameters (co-power, phase angle, and coherence) are e...

J. G. Nelson L. Hrebien



Effect of stimulus check size on multifocal visual evoked potentials  

Microsoft Academic Search

In this study we examined the effects of varying stimulus check size on multifocal visual evoked potential (VEP). We also evaluated the currently used cortical scaling of stimulus segments. The ObjectiVisionTM multifocal objective perimeter stimulates the eye with random check patterns at 56 cortically scaled segments within the visual field extending to a radius of 26°. All cortically scaled segments

Chandra Balachandran; Alexander I. Klistorner; Stuart L. Graham




EPA Science Inventory

The effects of age and stimulation frequency (0.2/sec, 1.0/sec, 2.0/sec, or 4.0/sec) on flash evoked potentials (FEPs) were investigated in awake, unsedated, unrestrained rats. Animals were tested daily from postnatal day (PND) 8 through PND 20, and every three or four days there...



EPA Science Inventory

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


Comparability of Rat and Human Visual-Evoked Potentials.  

National Technical Information Service (NTIS)

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

H. K. Hudnell W. K. Boyes



Brain stem auditory-evoked potentials in meningomyelocele  

Microsoft Academic Search

Brain stem auditory-evoked potentials (BAEPs) were recorded in 30 patients with meningomyelocele and shunted hydrocephalus ranging in age from birth to 33 years. Twenty-two of them had Chiari II malformation, one of which was symptomatic. In 22 cases, including 15 with Chiari II malformation, BAEPs were recorded repeatedly after periods ranging from 18 months to 7 years. The results were

Toshihiko Nishimura; Koreaki Mori; Yasufumi Uchida; Takayuki Ohira; Kazumi Tamura



Evoked-Potential Monitoring during Dorsal Root Entry Zone Surgery  

Microsoft Academic Search

Spinal cord evoked potentials (SCEP) in response to epispinal stimulation were measured in an experimental animal model designed to define further the value of electrophysiological monitoring during dorsal root entry zone (DREZ) surgery. Thirteen cats underwent microsurgical stereotactic thermal radiofrequency lesions of the DREZ. The postmortem histological examination of the location and extent of the lesions were compared with the

Marvin H. Bennett; L. Dade Lunsford; Osman Akin; A. Julio Martinez



Short-latency somatosensory evoked potentials in brain death  

Microsoft Academic Search

Simultaneous recording of somatosensory evoked potentials to median nerve stimulation above the upper and lower neck in brain-dead patients revealed that all cervical responses were preserved in 10%, whereas a marked reduction in amplitude or even loss of N 13b at the level of the C2 spinous process was observed in 90%. Of the patients, 55% revealed an additional loss

M. Stiihr; B. Riffel; E. Trost; A. Ullrich



EEG and evoked potentials in the intensive care unit  

Microsoft Academic Search

We review the principal aspects of EEG and evoked potential (EP) neuromonitoring in the intensive care unit. The electrophysiological methods allow functional assessment of comatose patients and can be used (a) as a help to diagnose the origin of coma, (b) as a means to predict outcome, and (c) for monitoring purposes. The combination of the EEG and long-, middle-,

J. M. Guérit



[Introduction to clinical investigation of olfactory evoked potentials].  


The modified own constructed device served automatically odour stimulus to nasal cavity allowed registration evoked cortical potentials in 30 patients with normal olfaction sensitivity and identification. It is possibly to differentiate the nerve V receptors responses on odour stimulation (latency range 180-360 ms) as well as nerve I receptors responses (latency range 380-600 ms). PMID:15307468

Obrebowski, Andrzej; Swidzi?ski, Teodor; Swidzi?ski, Piotr



Hearing in time: evoked potential studies of temporal processing.  


This article reviews the temporal aspects of human hearing as measured using the auditory evoked potentials. Interaural timing cues are essential to the detection and localization of sound sources. The temporal envelope of a sound--how it changes in amplitude over time--is crucially important for speech perception. Time is taken to integrate, identify, and dissolve auditory streams. These temporal aspects of human hearing can be examined using the auditory evoked potentials, which measure the millisecond-by-millisecond activity of populations of neurons as they form an auditory percept. Important measurements are the time taken to localize sounds on the basis of their interaural time differences as measured by the cortical N1 wave, the contribution of the vocal cord frequency and phonemic frequency to the perception of speech sounds as indicated by the envelope-following responses, the temporal integration of sound as assessed using the steady state responses, and the duration of auditory memory as shown in the refractory periods of the slow auditory evoked potentials. Disorders of temporal processing are a characteristic feature of auditory neuropathy, a significant component of the hearing problems that occur in the elderly, and a possible etiological factor in developmental dyslexia and central auditory processing disorders. Auditory evoked potentials may help in the diagnosis and monitoring of these disorders. PMID:24005840

Picton, Terence



Preliminary investigation of somatosensory evoked potentials in equine headshaking  

Microsoft Academic Search

The aim of this study was to develop a technique for recording electrical activity of the equine cerebral cortex following application of a noxious electrical stimulus to the maxillary branch of the trigeminal nerve in order to investigate trigeminal nerve neurophysiology in control and headshaking horses. Triphasic somatosensory evoked potentials (SEPs) were recorded using subcutaneous needle electrodes in four control

K. J. Pickles; T. J. Gibson; C. B. Johnson; V. Walsh; J. C. Murrell; J. E. Madigan



Brain-Computer Interfaces Based on Visual Evoked Potentials  

Microsoft Academic Search

Recently, electroencephalogram (EEG)-based brain- computer interfaces (BCIs) have become a hot spot in the study of neural engineering, rehabilitation, and brain science. In this article, we review BCI systems based on visual evoked potentials (VEPs). Although the performance of this type of BCI has already been evaluated by many research groups through a variety of laboratory demonstrations, researchers are still

Yijun Wang; Xiaorong Gao; Bo Hong; Chuan Jia; Shangkai Gao



[Workshop on electroretinography and visual evoked potentials].  


Studies of vision using electrophysiological techniques are tests which record functional alterations in very early phases of a disease. Full field flash ERG evaluates the integrity of the cones, rods and bipolar cells. It is obtained by photopsic stimulation with Ganzfeld and contact lens corneal electrodes or, alternatively, gold leaf or anchor electrodes. Five responses must be obtained: that of the rods, a maximum, oscillatory potentials, that of the cones and a flicker response. Pattern ERG is a response of the ganglionic cells, which is obtained by pattern reversal morphoscopic stimulation, with a bandwidth between 1 and 60 Hz. The fundamental waves (0.5 5 mV) are P50 (luminance) and N95 (pattern specific). This is of great value in the early diagnosis of glaucoma. VEP are electrical fields that are recorded in the calcarine cortex. They give information about alterations in the optic nerve, chiasm, radiations and cortex. Pattern VEP is obtained with a visual angle of between 13 and 14 . The fundamental wave P100 is evaluated according to its latency and amplitude, and by comparing it with a healthy eye. Flash VEP is only used on patients who do not collaborate or who present an opacity of media. PMID:12599140

Ucles Moreno, P


Somatosensory Evoked Potentials and Neuraxial Blood Flow in Central Nervous System Decompression Sickness.  

National Technical Information Service (NTIS)

Seven adult, conditioned dogs were anesthetized with pentobarbital sodium and prepared for measurement of upper lumbar, mid-thoracic and lower cervical evoked potentials (SEPs), cortical evoked potential (CEP), and aortic, right ventricular, and cerebrosp...

D. R. Leitch J. M. Hallenbeck



Layer by Layer Analysis of Evoked Potentials in the Paramedian Lobe of the Cerebellar Cortex.  

National Technical Information Service (NTIS)

The object of the investigation was to study which cerebellar cortical cells generate local and diffuse evoked potentials. The direction of the electric current was determined from changes in the evoked potentials as the microelectrode was moved from one ...

Y. I. Arshavskii M. B. Berkinblit O. I. Fukson



Laser-evoked potentials in post-herpetic neuralgia  

Microsoft Academic Search

Objective: We evaluated the reliability of laser-evoked potentials (LEPs) as a diagnostic tool in patients with post-herpetic neuralgia (PHN), i.e. a chronic painful condition that causes small-diameter fibre dysfunction. Furthermore, we sought information on pathophysiology of PHN pain.Methods: We recorded ‘late’ LEPs after stimulation of the supraorbital, upper cervical, lower cervical, upper thoracic, mid thoracic, and lower thoracic territories in

A Truini; M Haanpää; R Zucchi; F Galeotti; G. D Iannetti; A Romaniello; G Cruccu



Vestibular-evoked myogenic potentials in vestibular migraine  

Microsoft Academic Search

Sound-induced vestibular-evoked myogenic potentials (VEMPs) can be used to investigate saccular function, measured from the\\u000a tonically contracted sternocleidomastoid muscles (SCM) in response to loud sound stimuli. The aim of the present study was\\u000a to assess VEMPs in patients with vestibular migraine and to determine whether saccular function is affected by the disease.\\u000a Furthermore, tests such as tilts of subjective visual

Bernhard Baier; N. Stieber; M. Dieterich



Nondepolarizing neuromuscular blockade does not alter sensory evoked potentials  

Microsoft Academic Search

Objective. The objective of this study was to determine whether changes in nondepolarizing neuromuscular blockade (NMB) alter the latency\\u000a or amplitude of visual, brain stem auditory, or median nerve somatosensory evoked potentials.Methods. Ten adult cynomologousMacaca fascicularis monkeys were studied during continuous ketamine anesthesia infusion. The NMB was incrementally adjusted between no block\\u000a and complete block using infusions of vecuronium or

Tod B. Sloan



Long-latency motor evoked potentials in congenital hemiplegia  

Microsoft Academic Search

Objective: To investigate long-latency motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation in congenital hemiplegia (CH) and to seek for correlation with paretic hand movement deficits.Methods: MEPs were recorded from the first dorsal interosseous of both hands in 12 CH patients and 12 age-matched controls; dexterity and upper limb function were quantitatively assessed in both groups.Results: In CH patients,

Y. Vandermeeren; E. Bastings; L. Fadiga; E. Olivier



Pudendal nerve somatosensory evoked potentials in paediatrics: maturation aspects  

Microsoft Academic Search

Pudendal nerve somatosensory evoked potentials (PN-SSEPs) were recorded in 21 healthy children (age range: 3.3–13.3 years). The dorsal nerve of the penis\\/clitoris was stimulated and SSEPs were recorded at spinal L1-D12 and at cortical Cz?-Fz. Morphology, latency and amplitude of the cortical SSEPs were evaluated. A cortical response was obtained in all but two subjects. Cortical SSEPs were broader and

A Perretti; A Savanelli; P Balbi; G De Bernardo



Evoked autonomic skin potentials (Present views of the mechanisms)  

Microsoft Academic Search

This article presents the present views on the mechanisms of the evoked autonomic skin potentials (EASP). Consideration is\\u000a given to the research history of the electrodermal phenomena, methodological features of EASP recording, and possibilities\\u000a of their implementation in clinical neurology. The EASP is a suprasegmental somatoautonomic reflex, whose effector is presented\\u000a by sweat glands, and the posterior hypothalamus acts as

S. A. Kotel’nikov; A. D. Nozdrachev; M. M. Odinak; E. B. Shustov



Determining abnormal interocular latencies of multifocal visual evoked potentials  

Microsoft Academic Search

Purpose: To describe methods for measuring interocular latency differences of multifocal visual evoked potentials (mfVEP) and for determining regions with abnormal interocular latencies in patients. Methods: The mfVEPs from 100 individuals with normal visual fields and normal fundus examinations were analyzed. Individuals ranged in age from 21.6 to 92.4 years. The stimulus was a 60 sector, pattern-reversing dartboard display. Each

Donald C. Hood; Xian Zhang; Christopher Rodarte; E. Bo Yang; Nitin Ohri; Brad Fortune; Chris A. Johnson



Investigating Visual Function with Multifocal Visual Evoked Potentials  

Microsoft Academic Search

? With multifocal visual evoked potentials (mfVEPs) the visual field can be sampled for response abnormalities. Thus, mfVEPs\\u000a open the possibility of an objective visual field test. The issue, however, is greatly complicated by the variability of the\\u000a responses across the visual field and between subjects. \\u000a \\u000a ? Cortical morphology dictates the mfVEP shape and influences mfVEP magnitude; consequently it is

Michael B. Hoffmann


Activation of the brainstem precedes and outlasts the K-complex in humans.  


A K-complex (KC) in the electroencephalographs (EEGs) indicates a moderate depth of slow-wave sleep (SWS) in humans and animals. The cortical activities are upregulated during the periods between the KCs ("up state"), and it is proposed that temporarily stored memories during wakeful periods will be consolidated during these periods. Although the underlying mechanism for KCs is proposed to be in the cortex itself, the involvement of the brainstem has not been explored. Here we investigate the excitability changes of the brainstem preceding, during, and after KCs in humans. We simultaneously recorded brainstem auditory evoked potentials (BAEPs) with EEGs, and sequentially analyzed BAEPs around the KCs. The results showed a transient activation of the ventral brainstem preceding the KC and a sustained activation of the dorsal brainstem outlasting the KC. Thus, it is suggested that KCs are triggered by the activation of the brainstem and that the "up state" is maintained by the sustained activation of the brainstem. PMID:22155495

Kohsaka, S; Sakai, T; Kohsaka, M; Fukuda, N; Ariga, T



EEG, auditory evoked potentials and evoked rhythmicities in three-year-old children.  


According to our working hypothesis, the resonance properties of the brain systems play an important role in internal brain communications (e.g., Ba?ar, 1992; Ba?ar, Ba?ar-Eroglu, Demiralp & Schürmann, 1992). It was assumed that evoked potentials (EPs) reflect brain resonance properties, showing enhancement, time and frequency-locking during the poststimulus period. All these phenomena might be referred to the spontaneous (intrinsic) EEG rhythms according to the excitability rule and the related concept of brain system response susceptibility: a brain system could react to internal or external stimuli producing those rhythms or frequency components, which have already been present in intrinsic or spontaneous activity (Ba?ar, 1980). In order to test the hypothesis of response susceptibility, in the present paper we used an natural model--3-year-old children--to investigate how brain systems respond to external stimulation if their spontaneous rhythms are different in comparison to the spontaneous EEG rhythms in adults. For that purpose we used a combined time and frequency domain approach. The spectral characteristics of the spontaneous EEGs as well as the frequency components of auditory EPs elicited under identical auditory stimulation in 3-year-old children and adults aged 20-22 years were compared. Our observations support the hypothesis for response susceptibility; if in a given frequency channel the spontaneous brain rhythms are missing, they are also absent in the evoked and induced rhythmicities and vice versa: children at 3 years do not create alpha resonance upon sensory stimulation while they do not have developed EEG rhythms in the range of 8-15 Hz. Elicited under identical experimental conditions (auditory stimulation with fixed stimulus parameters) children and adult evoked rhythms differ. It was concluded that the AEPs recorded in 3-year-old children might be regarded mainly as a superposition of rhythmicities in delta and theta ranges. These rhythmicities are prolonged and delayed in comparison to the corresponding rhythms in adults. PMID:8050865

Ba?ar-Eroglu, C; Kolev, V; Ritter, B; Aksu, F; Ba?ar, E



Multimodality evoked potentials and electrically elicited blink reflex in optic neuritis  

Microsoft Academic Search

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

W. Tackmann; Th. Ettlin; H. Strenge



Effects of hypocapnia on canine spinal, subcortical, and cortical somatosensory-evoked potentials during isoflurane anesthesia  

Microsoft Academic Search

Although hyperventilation with hypocapnia is frequently used in the management of neurosurgical patients in whom sensory-evoked potentials may be monitored, the effects of hypocapnia on evoked potentials have not been described with precision. In the present experiment, the effects of randomized arterial carbon dioxide tensions of 20, 25, 30, and 35 mm Hg on spinal, subcortical, and cortical somatosensory-evoked potentials

Mary Ann Gravenstein; Frank Sasse; Kirk Hogan



The effects of cortical stimulation, anesthesia and recording site on somatosensory evoked potentials in the rat  

Microsoft Academic Search

The purpose of this study was to standardize the method of spinal cord monitoring with evoked potentials in the rat. Seventeen male Wistar rats were anesthetized with ?-chloralose and urethane. Somatosensory evoked potential (SEP) and cerebellar evoked potential (CEP) following sciatic nerve stimulation were mapped at different time points after induction of anesthesia. SEP peaks at latencies of 13–18 ms

Izumi Koyanagi; Charles H. Tator



Evoked sacral potentials in subjects with true premature ejaculation.  


Evoked sacral potentials were used to study the bulbo-cavernous reflex in 85 patients with true premature ejaculation (TPE) and in 52 subjects as a control group. In the perineal and perianal recordings the amplitudes of the evoked responses (means +/- SD) were 70 +/- 91.1 microV and 35.6 +/- 36 microV in the TPE patients, and 39.2 +/- 36.8 microV and 26 +/- 21.6 microV in the controls, respectively. Both these differences resulted significant (P less than 0.01 and P congruent to 0.05, respectively). Our results suggest a reflex hyperexcitability, or an impaired "modulation" of the motor neurons of the pudendal nucleus by the regulating upper centers in the TPE patients. PMID:3813046

Colpi, G M; Fanciullacci, F; Beretta, G; Negri, L; Zanollo, A



Spatial frequency-dependent asymmetry of visual evoked potential amplitudes.  


The extent to which pattern reversal evoked potential amplitudes are distributed symmetrically over the scalp was investigated as a function of stimulus spatial frequency. Nine right-handed male subjects viewed sinusoidal grating stimuli of 4.0 and 0.5 c/deg phase reversed every 900 msec. A visual half-field configuration enabled selective stimulation of the right- or left-hemisphere visual cortex. Evoked responses were recorded from the 2 cm above the inion (Oz) and at 7 and 13 cm lateral to Oz. Analyses of normalized evoked response amplitudes showed a significant asymmetry for the 4.0 c/deg stimulus; right-hemisphere amplitudes declined as a function of distance from the midline, while left-hemisphere amplitudes were greatest at the 7 cm recording site. No hemispheric differences were observed for the 0.5 c/deg stimulus; amplitudes for both hemispheres declined as a function of distance from the midline. The data are discussed in terms of hemispheric differences in morphology and functional asymmetries at early levels of sensory processing. PMID:8774045

van Orden, K F; House, J F



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


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. PMID:22510942

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



Cortical modulation of short-latency TMS-evoked potentials  

PubMed Central

Transcranial magnetic stimulation–electroencephalogram (TMS–EEG) co-registration offers the opportunity to test reactivity of brain areas across distinct conditions through TMS-evoked potentials (TEPs). Several TEPs have been described, their functional meaning being largely unknown. In particular, short-latency potentials peaking at 5 (P5) and 8 (N8) ms after the TMS pulse have been recently described, but because of their large amplitude, the problem of whether their origin is cortical or not has been opened. To gain information about these components, we employed a protocol that modulates primary motor cortex excitability (MI): low frequency stimulation of premotor area (PMC). TMS was applied simultaneously with EEG recording from 70 electrodes. Amplitude of TEPs evoked by 200 single-pulses TMS delivered over MI at 110% of resting motor threshold (rMT) was measured before and after applying 900 TMS conditioning stimuli to left PMC with 1 Hz repetition rate. Single subject analyses showed reduction in TEPs amplitude after PMC conditioning in a sample of participants and increase in TEPs amplitude in two subjects. No effects were found on corticospinal excitability as recorded by motor-evoked potentials (MEPs). Furthermore, correlation analysis showed an inverse relation between the effects of the conditioning protocol on P5-N8 complex amplitude and MEPs amplitude. Because the effects of the used protocol have been ascribed to a cortical interaction between premotor area and MI, we suggest that despite the sign of P5-N8 amplitude modulation is not consistent across participant; this modulation could indicate, at least in part, their cortical origin. We conclude that with an accurate experimental procedure early latency components can be used to evaluate the reactivity of the stimulated cortex.

Veniero, Domenica; Bortoletto, Marta; Miniussi, Carlo



Short latency vestibular evoked potentials in the chicken embryo  

NASA Technical Reports Server (NTRS)

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.

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



Evaluation of breast sensibility using dermatomal somatosensory evoked potentials.  


This study was undertaken to prospectively evaluate breast sensibility before and after reduction mammaplasty with a new, objective, and quantitative neurophysiologic method based on the anatomic knowledge of breast innervation and the congruent areas of dermatomal maps. An innovative application of dermatomal somatosensory evoked potentials was used to study the breast regions of 42 healthy women, bilaterally. The areas stimulated in each breast were the superior quadrant, the nipple-areola complex and the medial and lateral quadrants, and the inferior quadrant; these areas correspond to T3, T4, and T5 dermatomes, respectively, following the accepted concepts of segmentary innervation of the skin. The two groups of 21 patients each were formed according to breast size: group I comprised small-breasted, unoperated controls (brassiere cup size A or B); group II comprised macromastia patients (brassiere cup size C or greater) who presented to a general plastic surgery department for breast reduction surgery. First the authors established the normal range of latency and amplitude in the dermatomal somatosensory evoked potentials for the five areas stimulated in patients with small breasts and compared these parameters with those obtained from patients with macromastia. Then, after the macromastia patients underwent reduction mammaplasty using the McKissock technique, the authors compared the postoperative sensory values with their own preoperative values and with those from the small-breasted group. Using dermatomal somatosensory evoked potentials, they found that small breasts were statistically more sensitive than large breasts, which concurs with studies in the literature that use other methods to evaluate breast sensibility. They also found that after breast reduction, the macromastia patients presented statistically significant improvement in breast sensibility in relation to their own preoperative latency and amplitude values, with no statistical difference in amplitude with respect to the small-breasted group; this finding suggests that after breast reduction, sensibility similar to that of the small-breasted group can be considered a possibility. Furthermore, in comparisons of each of the five areas stimulated, there was no significant difference in values within the small-breasted group or within the macromastia group before or after surgery; this supports a possible overlap between adjacent dermatomes. This innovative application of dermatomal somatosensory evoked potentials is an objective, quantitative, and noninvasive method that has allowed the authors to evaluate breast sensibility and to compare postsurgical sensory outcomes. PMID:15253186

DelVecchyo, Carlos; Caloca, Jaime; Caloca, Jaime; Gómez-Jauregui, Jesica



Photo Data Retrieval via P300 Evoked Potentials  

NASA Astrophysics Data System (ADS)

In this letter, a new concept of life log retrieval using human brain activities is presented. The non-invasive electroencephalogram (EEG) recording was applied to have P300 evoked potentials during the photo retrieving tasks. Three subjects tried to select the photo images that interest them among nine according to their mental states. It was found that with four times EEG averaging, the performances of target photo selections could reach 90% for two subjects. This concept would be applicable in future to achieve intuitive retrieval of life log with large quantities of data.

Touyama, Hideaki


Transient visually evoked potentials to sinusoidal gratings in optic neuritis.  

PubMed Central

Transient visually evoked potentials (VEPs) to sinusoidal gratings over a range of spatial frequencies have been recorded in cases of optic neuritis. The use of the response to pattern onset in addition to the response to pattern reversal extended the range to higher spatial frequencies by up to two octaves. There was an increase in VEP delay and a greater degree of discrimination from a control group at higher spatial frequencies. This finding is discussed in the light of previous reports of luminance and checkerboard VEPs in demyelinating optic nerve disease. An attempt is made to relate amplitude changes in various VEP components to contrast sensitivity measurements in this group of patients.

Plant, G T



Classification of somatic evoked potentials through maximum entropy spectral analysis.  


Maximum entropy (ME) spectra are currently considered to be superior to spectra calculated by means of Fast Fourier Transforms (FFT) because the former offer higher resolution. However, in terms of classification of somatic evoked potentials (SEPs), FFT spectra are found to be better than ME spectra. An even better set of parameters for discriminating SEPs is the set of reflection coefficients derived in the process of calculating the ME spectra. They permit separation of SEPs obtained from monkeys with dorsal column lesion from SEPs obtained from normal monkeys, as well as distinguishing between SEPs obtained from large nerve fiber stimulation and SEPs from stimulation of all nerve fibers. PMID:6177493

Lam, C F; Zimmermann, K; Simpson, R K; Katz, S; Blackburn, J G



Evoked trigeminal nerve potential in chronic trichloroethylene intoxication.  


Results of a study of trigeminal nerve impairment resulting from trichloroethylene intoxication by the somatosensory-evoked potential method reveal three kinds of abnormalities: increased stimulation voltage, excessive latency delay with morphological abnormalities, and excessive graph amplitude. These abnormalities confirm clinical disturbance (hypesthesia of the trigeminal nerve area) and open debate about the real mechanism of trichloroethylene neurotoxicity. Industrial intoxication by solvents, particularly trichloroethylene, is common. We have conducted a study of 188 workers chronically exposed to trichloroethylene and have confirmed the selective neurological disturbances of this intoxication in the trigeminal nerve (20%) [3, 10]. We utilized a new experimental method, developed for studies of chronic intoxications effecting the median nerve [5, 8], of recording the somatosensory evoked potential following stimulation of the trigeminal nerve [4, 6, 7]. The workers in this study were selected following clinical evaluation of their facial sensitivity and trigeminal nerve reflexes. In this paper we present our preliminary results on 11 workers, 9 suffering effects of intoxication and 2 controls. PMID:7143527

Barret, L; Arsac, P; Vincent, M; Faure, J; Garrel, S; Reymond, F



Study for Analysis of the Multifocal Visual Evoked Potential  

PubMed Central

Purpose To introduce the clinical utility of the absolute value of the reconstructed waveform method in the analysis of multifocal visual evoked potential (mfVEP). Methods The mfVEP with 4-channel recording was performed using RETIscan® on 10 eyes of 10 normal subjects. Amplitudes were obtained from ring-shaped 6 areas and 4 sectors. The best visual evoked potential (VEP) response method and the absolute value of the reconstructed waveform method were compared in terms of analysis of the amplitudes. In order to assess the false positive rate of the examination, stimuli were administered with one-half of the cathode ray tube (CRT) monitor completely covered and the results were compared using 2 methods. Results The amplitudes in 6 areas and 4 sectors analyzed with the best VEP response method and the absolute value of the reconstructed waveform method showed no statistical difference (p > 0.05). The amplitude in the stimuli-blocked area of the absolute value of the reconstructed waveform method was smaller than that of the best VEP response method (p < 0.05) and the amplitude of the stimuli area showed no substantial difference between two methods (p > 0.05). Conclusions The absolute value of the reconstructed waveform method has similar reproducibility and lower level of false positives relative to the best VEP response method. Therefore, it can be considered as a useful method in the analysis of the mfVEP.

Park, Saemi; Park, Sang Hyouk; Chang, Jee Ho



Adaptive stimulus artifact reduction in noncortical somatosensory evoked potential studies.  


Somatosensory evoked potentials (SEP's) are an important class of bioelectric signals which contain clinically valuable information. The surface measurements of these potentials are often contaminated by a stimulus evoked artifact. The stimulus artifact (SA), depending upon the stimulator and measurement system characteristics, may obscure some of the information carried by the SEP's. Conventional methods for SA reduction employ hardware-based circuits which attempt to eliminate the SA by blanking the input during SA period. However, there is a danger of losing some of the important SEP information, especially if the stimulating and recording electrodes are close together. In this paper, we apply both linear and nonlinear adaptive filtering techniques to the problem of SA reduction. Nonlinear adaptive filters (NAF's) based on truncated second-order Volterra series expansion are discussed and their applicability to SA cancellation is explored through processing both simulated and in vivo SEP data. The performances of the NAF and the finite impulse response (FIR) linear adaptive filter (LAF) are compared by processing experimental SEP data collected from different recording sites. Due to the inherent nonlinearities in the generation of the SA, the NAF is shown to achieve significantly better SA cancellation compared to the LAF. PMID:9473840

Parsa, V; Parker, P A; Scott, R N



Evoked-potential changes following discrimination learning involving complex sounds  

PubMed Central

Objective Perceptual sensitivities are malleable via learning, even in adults. We trained adults to discriminate complex sounds (periodic, frequency-modulated sweep trains) using two different training procedures, and used psychoacoustic tests and evoked potential measures (the N1-P2 complex) to assess changes in both perceptual and neural sensitivities. Methods Training took place either on a single day, or daily across eight days, and involved discrimination of pairs of stimuli using a single-interval, forced-choice task. In some participants, training started with dissimilar pairs that became progressively more similar across sessions, whereas in others training was constant, involving only one, highly similar, stimulus pair. Results Participants were better able to discriminate the complex sounds after training, particularly after progressive training, and the evoked potentials elicited by some of the sounds increased in amplitude following training. Significant amplitude changes were restricted to the P2 peak. Conclusion Our findings indicate that changes in perceptual sensitivities parallel enhanced neural processing. Significance These results are consistent with the proposal that changes in perceptual abilities arise from the brain’s capacity to adaptively modify cortical representations of sensory stimuli, and that different training regimens can lead to differences in cortical sensitivities, even after relatively short periods of training.

Orduna, Itzel; Liu, Estella H.; Church, Barbara A.; Eddins, Ann C.; Mercado, Eduardo



[Postnatal development of evoked potentials in the rat somatosensory cortex].  


The developmental changes of evoked potentials in the somatosensory cortex were studied using Long-Evans rats of postnatal age from day 2 to day 55. A hole of appropriate size was made in the skull under urethane anesthesia (1.4 g/kg) and somatosensory evoked potentials (SEPs) were recorded with a silver-ball electrode. Electrical stimulation was applied to whisker C 3 follicle. The electrode was moved on the dura over the hemisphere and SEPs were displayed on an oscilloscope. When a maximum SEP was obtained 100 successive responses were digitally processed with a time resolutions of 100 microseconds and averaged. From the averaged SEP, various peak latencies and amplitudes were calculated. In response to electrical stimulation of the whisker follicle, a short-latency positive wave appeared on postnatal day 2 (PND 2) and the second positive wave was recorded on PND 8 and a negative wave appeared on PND 10. The latency of these waves shortened, while the amplitude increased with age. SEPs in developing rats attained adult pattern on PND 17, although both the values of latency and amplitude reach the limit on PND 55. The placing reaction was also tested from PND 9 to PND 15 to examine the functional development of whisker. All subjects displayed positive placing reaction of chin hair on PND 10. At this age all components appeared in the SEP, 1st positive, 2nd positive and negative waves. PMID:7699587

Seo, M; Uramoto, I



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


Object Intraoperative dorsal column mapping, transcranial motor evoked potentials (TcMEPs), and somatosensory evoked potentials (SSEPs) have been used in adults to assist with the resection of intramedullary spinal cord tumors (IMSCTs) and to predict postoperative motor deficits. The authors sought to determine whether changes in MEP and SSEP waveforms would similarly predict postoperative motor deficits in children. Methods The authors reviewed charts and intraoperative records for children who had undergone resection for IMSCTs as well as dorsal column mapping and TcMEP and SSEP monitoring. Motor evoked potential data were supplemented with electromyography data obtained using a Kartush microstimulator (Medtronic Inc.). Motor strength was graded using the Medical Research Council (MRC) scale during the preoperative, immediate postoperative, and follow-up periods. Reductions in SSEPs were documented after mechanical traction, in response to maneuvers with the cavitational ultrasonic surgical aspirator (CUSA), or both. Results Data from 12 patients were analyzed. Three lesions were encountered in the cervical and 7 in the thoracic spinal cord. Two patients had lesions of the cervicomedullary junction and upper spinal cord. Intraoperative MEP changes were noted in half of the patients. In these cases, normal polyphasic signals converted to biphasic signals, and these changes correlated with a loss of 1-2 grades in motor strength. One patient lost MEP signals completely and recovered strength to MRC Grade 4/5. The 2 patients with high cervical lesions showed neither intraoperative MEP changes nor motor deficits postoperatively. Dorsal columns were mapped in 7 patients, and the midline was determined accurately in all 7. Somatosensory evoked potentials were decreased in 7 patients. Two patients each had 2 SSEP decreases in response to traction intraoperatively but had no new sensory findings postoperatively. Another 2 patients had 3 traction-related SSEP decreases intraoperatively, and both had new postoperative sensory deficits that resolved. One additional patient had a CUSA-related SSEP decrease intraoperatively, which resolved postoperatively, and the last patient had 3 traction-related sensory deficits and a CUSA-related sensory deficit postoperatively, none of which resolved. Conclusions Intraoperative TcMEPs and SSEPs can predict the degree of postoperative motor deficit in pediatric patients undergoing IMSCT resection. This technique, combined with dorsal column mapping, is particularly useful in resecting lesions of the upper cervical cord, which are generally considered to be high risk in this population. Furthermore, the spinal cord appears to be less tolerant of repeated intraoperative SSEP decreases, with 3 successive insults most likely to yield postoperative sensory deficits. Changes in TcMEPs and SSEP waveforms can signal the need to guard against excessive manipulation thereby increasing the safety of tumor resection. PMID:24702615

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



Visual evoked potential monitoring of optic nerve function during surgery.  

PubMed Central

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.

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



Pain-related somatosensory evoked potentials in cortical reflex myoclonus.  

PubMed Central

To elucidate the sensitivity to pain stimuli in patients with cortical reflex myoclonus, pain-related somatosensory evoked potentials (pain SEPs) following CO2 laser stimulation and conventional electrically-stimulated SEPs (electric SEPs) were compared in four patients with cortical reflex myoclonus. The P25 peak of electric SEPs was considerably enhanced but the P320 potential of pain SEPs was of normal amplitude in all patients. After medication, myoclonus was reduced and the amplitude of P25 was decreased, but P320 showed no change. In our previous study of the scalp distribution in normal subjects, a subcortical site, probably the thalamus, was considered to be the generator source of P320. Because most pain stimuli do not reach the cortex, patients with cortical reflex myoclonus are not sensitive to pain stimuli and P320 in pain SEPs is not enhanced. Images

Kakigi, R; Shibasaki, H; Neshige, R; Ikeda, A; Mamiya, K; Kuroda, Y



Posterior femoral cutaneous nerve neuropathy and somatosensory evoked potentials.  


Isolated posterior femoral cutaneous nerve (PFCN) entrapment has only rarely been described in the literature and never documented electrophysiologically. We report an unusual occurrence of such an injury and use somatosensory evoked potentials (SSEP) to explore the extent of the lesion. A 40-year-old woman had localized numbness of the right posterior thigh after a left putamenal hemorrhage four years before this study. She made a complete recovery from her stroke within four months; however, she continued to experience decreased sensation in the right posterior thigh. Normal sural and peroneal nerve latencies, velocities, and amplitudes were obtained in the right leg. Electromyographic examination of right leg and related para spinal musculature was unremarkable. SSEP were then performed with CZ'-FZ (10-20 system) electrode placement. Normal sural, lateral femoral cutaneous, and posterior tibial responses were obtained bilaterally. Response differences consistent with an isolated right PFCN neuropathy were observed. The perfectly symmetric SSEP responses for the sural, lateral femoral cutaneous, and posterior tibial nerves obviate a central, and substantiate a peripheral, cause for the altered right PFCN evoked response. PMID:2827603

Dumitru, D; Marquis, S



Widespread activation of the brainstem preceding the recruiting rhythm in human epilepsies.  


The excitability change of the brainstem was investigated before and during the conspicuous epileptic discharge in six patients with generalized convulsive seizures. The discharge consisted of a short duration of recruiting rhythm, which was considered equivalent to the seizure discharge on electroencephalogram. The excitability of the brainstem was measured with the parameters (amplitude and area) of component waves (wave-III and -V) of brainstem auditory evoked potentials. The theoretical background of the analysis is that brainstem auditory evoked potentials are 'far-field' potentials, by which they convey the information on the activity change of the brainstem even during the paroxysmal discharge within the cortex. The excitability of both the ventral (parameters of wave-III) and the dorsal brainstem (parameters of wave-V) exhibited a synchronized change (activation-inactivation). They were enhanced from -2.4+/-0.4 s, reaching the maxima before the onset of the seizure discharge, and decayed corresponding to the emergence of the recruiting rhythm. The results suggest the possibility that the widespread (ventral and dorsal) and synchronized activation of the brainstem triggers the seizure discharge in human generalized epilepsy. During the widespread activation of the brainstem, both the thalamus and the cortex probably undergo a suppressed inhibitory state through the cholinergic activation, precipitating the seizure discharge. PMID:12435408

Kohsaka, S; Mizukami, S; Kohsaka, M; Shiraishi, H; Kobayashi, K



Protein profiling of formalin fixed paraffin embedded tissue: Identification of potential biomarkers for pediatric brainstem glioma  

PubMed Central

Little is known about the molecular characteristics of pediatric brainstem gliomas (BSG), which continue to have a dismal prognosis. Targeted molecular strategies are limited due to rarity of biopsy BSG specimen coupled with obstacles associated with the analyses of formalin-fixed paraffin- embedded (FFPE) autopsies. The objective of this study was to develop methodologies to successfully identify the proteome profile from these archived FFPE specimens. Peptides were extracted from both tumor and adjacent normal FFPE brainstem specimen and quantified using 18O proteolytic labeling strategy and LC-MS/MS analysis. The ingenuity pathway analysis software was used to elucidate interactions amongst differentially expressed proteins. We identified 188 proteins of which 54 (29%) were found up-regulated (?1.5-fold) in BSG compared to normal sections. Of these, 15 (28%) proteins have previously been reported as potential biomarkers for supratentorial malignant gliomas, while the rest appear to be exclusive to pediatric BSG. Because the majority of differentially expressed proteins are unique to BSG, we conclude that pediatric BSG is distinct from supratentorial gliomas. To the best of our knowledge, this is the first proteome profile of pediatric BSG, which may facilitate discovery of novel therapeutic targets for early diagnostics and improving prognostics.

Nazarian, Javad; Santi, Mariarita; Hathout, Yetrib; MacDonald, Tobey J.



Conscious Wireless Electroretinogram and Visual Evoked Potentials in Rats  

PubMed Central

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.

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



Multifocal visual-evoked potential in unilateral compressive optic neuropathy  

PubMed Central

Aim To evaluate the effects of unilateral compressive optic neuropathy on amplitude and latency of multifocal visual evoked potentials (mfVEPs). Methods Static automated perimetry and mfVEP recordings were obtained from six patients with presumed meningiomas affecting one optic nerve. Monocular and interocular amplitude and latency analyses were performed and compared with normal control subjects. Results The change in the mfVEP amplitude agreed with visual field findings with regard to topography and severity of deviation from normal. The delay in recordable responses from affected eyes ranged from 7.6 to 20.7?ms (interocular analysis) and 7.9 to 13.9?ms (monocular analysis). Conclusions Compressive optic neuropathy decreases the amplitude and increases the latency of the mfVEP. The changes in latency were similar to those seen in optic neuritis but larger than those in ischaemic optic neuropathy and glaucoma.

Semela, Linda; Yang, E Bo; Hedges, Thomas R; Vuong, Laurel; Odel, Jeffery G; Hood, Donald C



Threshold prediction from the auditory 40-Hz evoked potential.  


This is an investigation of the accuracy with which the 40-Hz evoked potential (EP) threshold can be used to predict low frequency behavioral audiometric thresholds. The EP thresholds for 500 and 1000 Hz tone bursts were compared with behavioral thresholds obtained from 40 hearing-impaired ears. Correlation coefficients (between EP and behavioral thresholds) of 0.79 and 0.87 were obtained for the 500 and 1000 Hz signals, respectively. Confidence intervals for EP estimates of behavioral thresholds were -10 to +30 dB for 500 Hz signals and -20 to +20 for 1000 Hz. Problems associated with the use of the EP for predicting behavioral thresholds are discussed. PMID:6510584

Lynn, J M; Lesner, S A; Sandridge, S A; Daddario, C C



Visual evoked potentials in neuromyelitis optica and its spectrum disorders.  


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. PMID:24009163

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



Pattern visual evoked potential luminance and multiple sclerosis.  


Pattern visual evoked potentials (PVEPs) were recorded from 111 patients classified as having possible, probable or definite multiple sclerosis. Patients were stimulated with a checkerboard pattern using high and low luminances in order to test the hypothesis that an attenuated pattern luminance increases the detection rate of PVEP abnormalities. With increasing certainty of diagnosis, there was a concomitant increase in the incidence of PVEP abnormalities. However, there was no evidence that stimulating with a lower luminance pattern enhanced the sensitivity of the test. The same findings were also apparent when the patient data was analyzed according to the presence or absence of a history of optic neuritis or other visual symptoms. It is concluded that, within the luminance limits used in this study, the role of varied luminance in detecting demyelinating lesions in the optic nerves using the PVEP is minimal, although there was some limited evidence that a high level of luminance may be more appropriate than a low level. PMID:1395053

Frith, R W; Shaw, N A; Aitcheson, F



The impact of emotion on respiratory-related evoked potentials  

PubMed Central

Emotion influences the perception of respiratory sensations, although the specific mechanism underlying this modulation is not yet clear. We examined the impact of viewing pleasant, neutral, and unpleasant affective pictures on the respiratory-related evoked potential (RREP) elicited by a short inspiratory occlusion in healthy volunteers. Reduced P3 amplitude of the RREP was found for respiratory probes presented when viewing pleasant or unpleasant series, when compared to those presented during the neutral series. Earlier RREP components, such as Nf, P1, N1, and P2, showed no modulation by emotion. The results suggest that emotion impacts the perception of respiratory sensations by reducing the attentional resources available for processing afferent respiratory sensory signals.

von Leupoldt, Andreas; Vovk, Andrea; Bradley, Margaret M.; Keil, Andreas; Lang, Peter J.; Davenport, Paul W.



Preliminary investigation of somatosensory evoked potentials in equine headshaking.  


The aim of this study was to develop a technique for recording electrical activity of the equine cerebral cortex following application of a noxious electrical stimulus to the maxillary branch of the trigeminal nerve in order to investigate trigeminal nerve neurophysiology in control and headshaking horses. Triphasic somatosensory evoked potentials (SEPs) were recorded using subcutaneous needle electrodes in four control and four headshaking horses under general anaesthesia. Dural electroencephalography electrodes were used to record SEPs in one further control and one further headshaking horse. Headshaking horses appeared to have decreased middle latency and inter-peak intervals following stimulation of the trigeminal nerve compared with control horses, supporting abnormal trigeminal nerve physiology in equine headshaking. PMID:21546406

Pickles, K J; Gibson, T J; Johnson, C B; Walsh, V; Murrell, J C; Madigan, J E



Vestibular-evoked myogenic potentials, clinical evaluation, and imaging findings in multiple sclerosis.  


Vestibular-evoked myogenic potentials (VEMP), short-latency electromyographic responses elicited by acoustic stimuli, evaluate the function of vestibulocollic reflex and may give information about brainstem function. The aim of the present study is to evaluate the potential contribution of VEMP to the diagnosis of multiple sclerosis (MS). Fifty patients with MS and 30 healthy control subjects were included in this study. The frequency of VEMP p1-n1 and n2-p2 waves; mean p1, n1, n2, and p2 latency; and mean p1-n1 and n2-p2 amplitude were determined. The relation between clinical and imaging findings and VEMP parameters was evaluated. The p1-n1 and n2-p2 waves were more frequently absent in MS than in control subjects [p1-n1 wave absent: MS, 25 (25 %) ears; control, 6 (10 %) ears; P ? 0.02] [n2-p2 wave absent: MS, 44 (44 %) ears; control, 7 (12 %) ears; P ? 0.001]. The mean p1-n1 amplitude was lower in MS than in control subjects (MS, 19.1 ± 7.2 ?V; control, 23.3 ± 7.4 ?V; P ? 0.002). A total of 24/50 (48 %) MS patients had VEMP abnormalities (absent responses and/or prolonged latencies). VEMP abnormalities were more frequent in patients with than without vestibular symptoms (P ? 0.02) and with brainstem functional system score (FSS) ? 1 than FSS = 0 (P ? 0.02). In patients with MS, absence of p1-n1 wave was more frequent in patients with than without vestibular symptoms [absence of p1-n1 wave: vestibular symptoms, 9 (45 %) ears; no vestibular symptoms, 16 (20 %) ears; P ? 0.03] and patients with Expanded Disability Status Scale (EDSS) score ? 5.5 [absence of p1-n1 wave: EDSS ? 5.5, 7 (70 %) ears; EDSS <5.5, 18 (20 %) ears; P ? 0.001]. Abnormal VEMP may be noted in MS patients, especially those with vestibular symptoms and greater disability. The VEMP test may complement other studies for diagnosis and follow-up of patients with MS. PMID:23807120

Güven, Hayat; Bay?r, Omer; Aytaç, Emrah; Ozdek, Ali; Como?lu, Selim Selçuk; Korkmaz, Hakan



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

PubMed Central

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

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



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

PubMed Central

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

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



S(+)Ketamine Attenuates Myogenic Motor-Evoked Potentials at or Distal to the Spinal ??Motoneuron  

Microsoft Academic Search

We investigated the effect of S()-ketamine on spinal cord evoked potentials (ESCPs) and myogenic motor- evoked potentials after electrical stimulation of the motor cortex in a rabbit model. This study was de- signed to characterize the relationship between ESCP characteristics and corresponding changes in com- pound muscle action potentials (CMAPs) derived from fore and hind limbs. Direct (D) and indirect

Kai-Michael Scheufler; Christof Thees; Joachim Nadstawek; Josef Zentner



Spinal Cord-Evoked Potentials and Muscle Responses Evoked by Transcranial Magnetic Stimulation in 10 Awake Human Subjects  

Microsoft Academic Search

Transcranial magnetic stimulation (TCMS) causes leg muscle contractions, but the neural structures in the brain that are activated by TCMS and their relationship to these leg muscle responses are not clearly understood. To elucidate this, we concomitantly recorded leg muscle responses and thoracic spinal cord-evoked potentials (SCEPs) after TCMS for the first time in 10 awake, neurologically intact human subjects.

David A. Houlden; Michael L. Schwartz; Charles H. Tator; Peter Ashby; William A. MacKay



Effects of Low to Moderate Lead Exposure on Brainstem Auditory Evoked Potentials in Children.  

National Technical Information Service (NTIS)

Complex auditory processing deficits have been reported in children with asymptomatic lead (Pb) exposure (1,2) as well as acute Pb poisoning (3). Hearing thresholds have not been systematically evaluated in Pb exposed children, although hearing impairment...

C. Barton D. Kleinbaum G. Robinson S. Baumann S. Schroeder



Nitrous oxide and isoflurane are synergistic with respect to amplitude and latency effects on sensory evoked potentials  

Microsoft Academic Search

Objective  Combinations of anesthetic agents are frequently employed to produce the desired clinical effect. No systematic study has\\u000a been conducted on the effect of the combination of nitrous oxide with a potent inhalational agent such as isoflurane on sensory\\u000a evoked responses.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Median nerve somatosensory evoked responses from the cervical and cortical regions (SSEP), auditory brainstem responses (ABR)\\u000a and flash visual evoked

Tod Sloan; H. Sloan; J. Rogers



Pain-evoked potentials: what do they really measure?  


Cerebral evoked potentials (EPs) in response to painful stimuli have been recorded since the 1970s. Based on the apparent relationship of the response amplitude to intensity of stimulation, these potentials are conventionally interpreted as reflecting the sensory-discriminative aspects of pain. As such, pain-EPs provide an objective measure for sensation of pain. An alternative interpretation regards the pain-EP as comprised of at least two overlapping components, one pain-specific, the other, a P300 wave. In the case of pain, the P300 may reflect the degree of discomfort or unpleasantness, thus reflecting the emotional-motivational aspect. To establish the nature of the pain-EP, mini doses of a benzodiazepine, counterbalanced with placebo, were given to 6 normal volunteers. Benzodiazepines decrease anxiety, and so diminish the emotional response to pain, but they have no analgesic effect. In all subjects, pain perception was unchanged, while the EP wave was almost completely obliterated. We conclude that the pain-EP reflects the emotional-motivational response to pain rather than the sensory-discriminative. Thus, it provides a useful neurophysiological tool for studying the emotions associated with pain. PMID:8893656

Zaslansky, R; Sprecher, E; Katz, Y; Rozenberg, B; Hemli, J A; Yarnitsky, D



Monitoring of sensory evoked potentials is highly reliable and helpful in the operating room.  


Because short-latency evoked potentials are relatively resistant to anesthetic agents, they can be used to monitor neural pathways during surgical procedures. The use of median nerve somatosensory evoked potentials to localize the central sulcus is an established aid of indisputable value in neurosurgical procedures involving cortical incisions for resection of certain epileptic foci, vascular malformations, or neoplasms near the central area of the brain. Likewise, recording of intraoperative nerve action potentials is currently regarded as indispensable in management of the neuroma-incontinuity after peripheral nerve trauma, as this evoked potential monitoring technique provides the only reliable method of distinguishing between axonotmetic and neurotmetic lesions. Evoked potential monitoring has been of value during many other types of surgical procedures, including cerebral aneurysm clipping, carotid endarterectomy, aortic procedures, microvascular decompression for trigeminal neuralgia and hemifacial spasm, acoustic neuroma resection, and a variety of spinal procedures. A detailed review of the literature is presented on the use of evoked potential monitoring for one of the more common indications: scoliosis surgery. Many orthopedic surgeons use the "wake-up test" only if the somatosensory evoked potentials change during surgery. A detailed review of the few reported cases of "false negative" evoked potentials is presented. The dearth of convincing reports of such phenomena in the face of so many positive experiences should persuade even the skeptical that monitoring of evoked potentials is a highly reliable and helpful intraoperative tool. PMID:3546609

Friedman, W A; Grundy, B L



Spatial profile of back-propagating action potential-evoked Ca2+ transients in basal dendrites.  


Calcium influx in basal dendrites evoked by back-propagating action potentials is important for understanding the input-specific modulation of synaptic transmission. Calcium transients evoked by back-propagating action potentials were measured for the basal dendrites of layer II/III pyramidal neurons in visual cortex slices. In contrast to apical dendrites, the peak calcium transients evoked by a single somatic action potential increased with distance from the soma. The peak calcium transients evoked by bursts of back-propagating action potentials (three or five pulses, 20 Hz) were greater than those evoked by a single back-propagating action potential. These different spatial profiles for calcium transients triggered by back-propagating action potentials between apical and basal dendrites suggest that the segregated inputs from brain areas might be modulated in different ways, according to their synaptic location. PMID:16407758

Cho, Kwang-Hyun; Kim, Myung-Jun; Yoon, Shin Hee; Hahn, Sang June; Jo, Yang-Hyeok; Kim, Myung-Suk; Rhie, Duck-Joo



Disappearance of click-evoked potentials on the neck of the guinea pig by pharmacological and surgical destruction of the peripheral vestibular afferent system.  


In order to establish an animal model of acoustically evoked vestibulo-collic reflex, the so-called vestibular evoked myogenic potential in humans, potentials evoked by loud clicks on the neck of the guinea pig were recorded using subjects whose peripheral vestibular endorgans or vestibular afferents had been damaged. Four normal control guinea pigs, four guinea pigs that received an intramuscular injection of gentamicin for 20 days (90 mg/kg/day) and five guinea pigs whose vestibular nerves were surgically sectioned were used in this study. Under general anesthesia with an intraperitoneal injection of pentobarbital sodium (40 mg/kg), auditory brainstem responses (ABRs) were recorded. Then, potentials evoked by loud clicks on the pre-vertebral muscle at the level of the third cervical vertebral bone were recorded using silver ball electrodes. As a result, a distinctive negative peak (NP) with a latency of 6-8 ms was recorded in all animals in the control group. NP was not observed in the gentamicin-administered group while ABR was preserved. After sectioning the vestibular nerve, NP was abolished while ABR was preserved. From these results, NP could be of vestibular origin. These results are in agreement with a previous report of NP using subjects whose cochlea had been damaged pharmacologically. PMID:14553899

Matsuzaki, Masaki; Murofushi, Toshihisa



Accurate Identification of Evoked Potentials by Waveform Decomposition Using Discrete Cosine Transform Modeling.  

National Technical Information Service (NTIS)

This paper introduces a method for decomposing the component responses of the evoked potentials. The decomposition was realized by zero-pole modeling of the evoked potentials in the discrete cosine transform (DCT) domain. It was found that the DCT coeffic...

O. Bai M. Nakamura H. Shibasaki



Dermatomal and mixed nerve somatosensory evoked potentials in the diagnosis of neurogenic thoracic outlet syndrome  

Microsoft Academic Search

To evaluate the diagnostic utility of dermatomal and mixed nerve somatosensory evoked potentials (SEPs) in patients with thoracic outlet syndrome (TOS) and to compare their value with routine electrodiagnostic methods, we studied a group of 44 patients with neurogenic TOS and 30 healthy controls. In addition to bilateral median and ulnar SEPs, evoked potentials were recorded after stimulation of C6

Raif Cakmur; Fethi Idiman; Elif Akalin; Ahmet Genç; Görsev G Yener; Vesile Öztürk



BAER - brainstem auditory evoked response  


... be a sign of hearing loss , multiple sclerosis , acoustic neuroma , or stroke. Abnormal results may also be due to: Brain injury Brain malformation Brain tumor Central pontine myelinolysis Speech ...


[Multimodal evoked potentials and heart rate variability in comatose patients--1: Method of measuring and normal values].  


Multimodal EPs and heart rate variability-measurements in comatose patients have been performed for few years at the university hospitals of Graz and Erlangen. The following data and parameters are analysed and discussed: brainstem auditory evoked potentials, mechanical evoked long-latency SEP, VEP recorded over the central and occipital region and heart rate variability (HRV). The method of data acquisition and processing is described and normative data are introduced. For the long-latency EP-components a signal-to-noise-ratio (SNR) is calculated. SNR is defined as ratio of the largest EP peak-to-peak amplitude and the mean amplitude (standard deviation) of a period prior to the stimulation. An unmeasurable or questionable EP is defined when SNR less than 2.6. For the vertex-SEP the following mean +/- standard deviation was obtained: SNR = 10.6 +/- 4.6; the vertex VEP was calculated with SNR = 7.0 +/- 3.0. The SNR of the bipolar recorded occipitally VEP was 3.9 +/- 2.0. Heart rate variability measurements in normal persons revealed the following mean +/- standard deviation at a heart rate of 67.8/min +/- 10.8/min: HRV = 7.8% +/- 2.5%. PMID:3115751

Pfurtscheller, G; Druschky, K; Kamp, H D; Schwarz, G; Litscher, G; Rügheimer, E; Neundörfer, B; List, W



Effects of blood glutamate scavenging on cortical evoked potentials.  


It is well known that traumatic or ischemic brain injury is followed by acute excitotoxicity caused by the presence of abnormally high glutamate (Glu) in brain fluids. It has recently been demonstrated that excess Glu can be eliminated from brain into blood following the intravenous administration of oxaloacetate (OxAc), which, by scavenging blood Glu, induces an enhanced and neuroprotective brain-to-blood Glu efflux. In this study, we subjected rats to intravenous OxAc administration (i.v., 12.5, 25, and 50 mg/kg, respectively), and studied its effects on somatosensory evoked cortical potentials (EPs). Against our expectation, the amplitudes of EPs did not decrease but increased in a dose- and time-dependent manner after OxAc administration. Similar effects were observed when blood Glu scavenging was enhanced by combining OxAc (12.5 mg/kgbw) with recombinant glutamate-oxaloacetate transaminase (GOT, 0.14 nmol/100 g rat). On the basis of these results, we suggest that the changes of amplitudes of the EPs involve not only a glutamatergic but also the weakening of a GABAergic component. We cannot rule out the possibility that OxAc penetrates into the brain and improves mitochondrial functions. PMID:20607387

Nagy, Dávid; Knapp, Levente; Marosi, Máté; Farkas, Tamás; Kis, Zsolt; Vécsei, László; Teichberg, Vivian I; Toldi, József



Vestibular evoked myogenic potentials in patients with BPPV  

PubMed Central

Summary Background The probable cause of Benign Paroxysmal Positional Vertigo (BPPV) is a degeneration of the oto lithic organs (utricle and saccule). The aim of the study is to find possible alterations in Vestibular Evoked Myogenic Potentials (VEMP) recordings in BPPV patients, because the saccule is part of the VEMP pathway. Material/Methods 27 BPPV patients (24 unilateral and 3 bilateral) aged 20 to 70 years and 30 healthy age matched controls. BPPV was diagnosed by the upbeating geotropic nystagmus found in the supine position with the head overextended towards one side. The subjects were investigated with pure tone audiometry, bi-thermal caloric test with electronystagmographic (ENG) recording, and VEMP recording. Results P1 latency and N1 latency did not present any statistical difference between control ears and affected ears of the BPPV population. The percentage of abnormal VEMP in the BPPV population was statistically higher than in the control ears (p<0.005). No significant relationship could be shown between the occurrence of Canal Paresis and abnormal VEMP. No relationship was found between the side (right or left ear) where BPPV appeared clinically and the side where abnormal VEMP was registered. Conclusions BPPV is a clinical entity associated with increased occurrence of abnormal VEMP recordings, possibly due to degeneration of the saccular macula, which is part of the neural VEMP pathway.

Korres, Stavros; Gkoritsa, Eleni; Giannakakou-Razelou, Dimitra; Yiotakis, Ioannis; Riga, Maria; Nikolpoulos, Thomas P.



Cortical auditory evoked potentials in unsuccessful cochlear implant users.  


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 and discriminate auditory stimuli in 10 unsuccessful implant users aged 8-10 years (CI) and 10 healthy age-matched controls with normal hearing (NH). Pure tones (1 and 2 kHz) and double consonant-vowel syllables were applied. The stimuli were presented in an oddball paradigm that required the subjects to react consciously. The latencies and amplitudes of the P1, N1, P2, N2 and P3 waves were analyzed, in addition to reaction times and number of responses. Significant differences in the average response times and number of responses were observed between the CI and NH groups. The latencies also indicate that the CI group took longer to perceive and discriminate between tonal and speech auditory stimuli than the NH group. PMID:23621479

Munivrana, Boška; Mildner, Vesna



Effect of pupil size on multifocal pattern visual evoked potentials.  


The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal. PMID:12880463

Martins, Alessandra; Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L; Billson, Francis A



Effect of stimulus check size on multifocal visual evoked potentials.  


In this study we examined the effects of varying stimulus check size on multifocal visual evoked potential (VEP). We also evaluated the currently used cortical scaling of stimulus segments. The ObjectiVision multifocal objective perimeter stimulates the eye with random check patterns at 56 cortically scaled segments within the visual field extending to a radius of 26 degrees. All cortically scaled segments have equal number of checks, which gradually increase in size from the center to the periphery, proportional to the size of the segment. Stimuli with 9, 16, 25, 36 and 49 checks/segment were tested on 10 eyes belonging to 10 normal subjects. The check size varied inversely with number of checks per segment. VEP was recorded using bipolar occipital cross electrodes (7 min/eye), the amplitude and latency of responses obtained were compared with the check size at different eccentricities. Our findings suggest that the existing setting with 16 checks/segment subtending 26' to 140' from center to periphery, is the most effective amongst all the check sizes. Decreasing the check size prolongs the latency in the central field only. Cortical scaling of segments generates responses of the same order of magnitude throughout the field, but could be improved slightly to enhance the signal from the outer two rings. PMID:12678283

Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L



Does speaker presentation affect auditory evoked potential thresholds in goldfish?  


The auditory evoked potential (AEP) recording technique has proved to be a very versatile and successful approach in studying auditory sensitivities in fishes. The AEP protocol introduced by Kenyon, Ladich and Yan in 1998 using an air speaker with the fish positioned at the water surface gave auditory thresholds in goldfish very close to behavioural values published before. This approach was subsequently modified by several laboratories, raising the question whether speaker choice (air vs. underwater) or the position of subjects affect auditory threshold determination. To answer these questions, the hearing specialist Carassius auratus was measured using an air speaker, an underwater speaker and alternately positioning the fish directly at or 5cm below the water surface. Mean hearing thresholds obtained using these 4 different setups varied by 5.6dB, 3.7dB and 4dB at 200Hz, 500Hz and 1000Hz, respectively. Accordingly, pronounced differences in AEP thresholds in goldfish measured in different laboratories reflect other factors than speaker used and depth of the test subjects, namely variations in threshold definition, background noise, population differences, or calibration errors. PMID:19602445

Ladich, Friedrich; Wysocki, Lidia Eva



Visual-evoked cortical potentials in dissociated vertical deviation.  


It is debatable whether chiasmatic misrouting of temporal optic-nerve fibers (similar to that found in ocular albinism) is also characteristic of dissociated vertical deviation. Pattern appearance, pattern reversal, and diffuse-flash, monocular full-field visual-evoked cortical potentials were recorded from albino and normal human subjects and subjects with dissociated vertical deviation. Pattern appearance was the most reliable stimulus for evaluating lateralization (albino-type misrouting) in adult albino patients, and diffuse-flash stimulation was almost as reliable in children. Pattern reversal was found to be an unreliable indicator. Lateralization was not evident among patients with dissociated vertical deviation, as determined by the three modes of stimulation. Our data supported earlier findings that pattern appearance is the most appropriate technique to detect lateralization. Our findings differed from those of previous reports in demonstrating that reliability of the lateralization phenomenon increases with age up to approximately 15 years. Pattern reversal stimulation was not reliable in patients with horizontal nystagmus. PMID:1957909

Zubcov, A A; Fendick, M G; Gottlob, I; Wizov, S S; Reinecke, R D



On the use of evoked potentials for quantification of pain.  


Pain is a subjective and individual sensation causing major discomfort. So, it is necessary to put into practice methods to objectively quantify it. Several studies indicate that evoked potentials (EP) generate responses which may reflect painful processes. This study reports the results of the application of two different protocols by using biopotentials to objectively measure pain. The first (protocol 1) evaluates the relation between pain, induced by electrical stimulation, and subjective perception and also with nociceptive flexion reflex (NFR) represented by muscle activity (electromyography) detected on the femoral biceps after sural nerve stimulation. The second protocol (protocol 2) verifies whether there is some correlation between M-wave parameters and subjective pain sensation. The results obtained from protocol 1 suggest that the area of the EMG envelope and entropy estimated from the EMG activity are correlated with subjective sensation of pain. The analysis of data obtained from protocol 2 shows a correlation between the global minimum of the M-wave and pain increase. These results contribute to studies which seek to objective measures for pain quantification based on the analysis of biopotentials. PMID:23366206

Oliveira, M I; Machado, A R P; Chagas, V G S; Granado, T C; Pereira, A A; Andrade, A O



Measuring action potential-evoked transmission at individual synaptic contacts  

PubMed Central

In the neuronal culture experimental system, the total synaptic connection between two neurons can consist of large numbers of synaptic sites, each behaving probabilistically. Studies of synaptic function with paired recordings typically consider the summed response across all of these sites and from this infer the average response. Understanding of synaptic transmission and plasticity could be improved by examination of activity at as few synaptic sites as possible. To this end, we develop a system for recording responses from individual contacts. It relies on a precisely regulated pneumatic/hydrostatic pressure system to create a microenvironment within which individual synapses are active, and an acoustic signature method to monitor the stability of this microenvironment noninvasively. With this method we are able to record action potential-evoked postsynaptic currents consistent with individual quanta. The approach does not distort synaptic current waveforms and permits stable recording for several hours. The method is applied to address mechanisms of short-term plasticity, the variability of latency at individual synaptic sites and, in a preliminary experiment, the independence of nearby synapses on the same axon.

Nauen, David W; Bi, Guo-Qiang



Topographic visually evoked potentials induced by stereoptic stimulus.  

PubMed Central

Topographic processes of brain activity during stereopsis were investigated by means of two different principles, with a real stereo target and a computer stereogram. Use of either principle produced the same tendency: an electrically negative focus started from the central region of the scalp and moved to the parietal and occipital regions. These flows of excitation were seen during a period of 90 to 170 ms. The difference between these two stimulus represented a return of the negative focus from the occipital pole to the parietal region in the real stereo target and a spread of the negative focus to the temporal region in the computer stereogram. Since monocular viewing of a real stereo target produces a similar visually evoked potentials wave form but with less intensity, the negative focus in binocular viewing may be due to the enhancement of binocular cells and disparity sensitive neurons in a wide area of the brain cortex. Thus stereoptic brain responses start from the central and parietal regions and move to the occipital region, making a flow of excitation. Images

Fukai, S



A Subspace Method for Dynamical Estimation of Evoked Potentials  

PubMed Central

It is a challenge in evoked potential (EP) analysis to incorporate prior physiological knowledge for estimation. In this paper, we address the problem of single-channel trial-to-trial EP characteristics estimation. Prior information about phase-locked properties of the EPs is assesed by means of estimated signal subspace and eigenvalue decomposition. Then for those situations that dynamic fluctuations from stimulus-to-stimulus could be expected, prior information can be exploited by means of state-space modeling and recursive Bayesian mean square estimation methods (Kalman filtering and smoothing). We demonstrate that a few dominant eigenvectors of the data correlation matrix are able to model trend-like changes of some component of the EPs, and that Kalman smoother algorithm is to be preferred in terms of better tracking capabilities and mean square error reduction. We also demonstrate the effect of strong artifacts, particularly eye blinks, on the quality of the signal subspace and EP estimates by means of independent component analysis applied as a prepossessing step on the multichannel measurements.

Georgiadis, Stefanos D.; Ranta-aho, Perttu O.; Tarvainen, Mika P.; Karjalainen, Pasi A.



The adaptive chirplet transform and visual evoked potentials.  


We propose a new approach based upon the adaptive chirplet transform (ACT) to characterize the time-dependent behavior of the visual evoked potential (VEP) from its initial transient portion (tVEP) to the steady-state portion (ssVEP). This approach employs a matching pursuit (MP) algorithm to estimate the chirplets and then a maximum-likelihood estimation (MLE) algorithm to refine the results. The ACT decomposes signals into Gaussian chirplet basis functions with four adjustable parameters, i.e., time-spread, chirp rate, time-center and frequency-center. In this paper, we show how these four parameters can be used to distinguish between the transient and the steady-state phase of the response. We also show that as few as three chirplets are required to represent a VEP response. Compared to decomposition with Gabor logons, a more compact representation can be achieved by using Gaussian chirplets. Finally, we argue that the adaptive chirplet spectrogram gives a superior visualization of VEP signals' time-frequency structures when compared to the conventional spectrogram. PMID:16830941

Cui, Jie; Wong, Willy



An analytical model of the vestibular evoked myogenic potential.  


The vestibular evoked myogenic potential (VEMP) can be modeled (scaling factors aside) as a convolution of the motor unit action potential (MUAP) of a representative motor unit, h(t), with the temporal modulation of the MUAP rate of all contributing motor units, r(t). Accordingly, the variance modulation associated with the VEMP can be modeled as a convolution of r(t) with the square of h(t). To get a deeper theoretical understanding of the VEMP phenomenon, a specific realization of this general model is investigated here. Both r(t) and h(t) were derived from a Gaussian probability density function (in the latter case taking the first derivative). The resulting model turned out to be simple enough to be evaluated analytically in the time and in the frequency domain, while still being realistic enough to account for the basic aspects of the VEMP generation. Perhaps the most significant conclusion of this study is that, in the case of noisy data, it may be difficult to falsify the hypothesis of a rate modulation of infinitesimal duration. Thus, certain aspects of the data (particularly the peak amplitudes) can be interpreted using a short-modulation approximation rather than the general model. The importance of this realization arises from the fact that the approximation offers an exceptionally simple and convenient way for a model-based interpretation of experimental data, whereas any attempt to use the general model for that purpose would result in an ill-posed inverse problem that is far from easy to solve. PMID:21771601

Lütkenhöner, Bernd; Basel, Türker



Evoked Potentials to Evaluate Mechanisms of Peripheral Nerve Repair Including Computerized, Non-invasive Recording.  

National Technical Information Service (NTIS)

The purpose of these studies is to develop earlier and more accurate methods of evaluating peripheral nerve injuries than are commonly in use. Nerve action potential recording has been combined with evoked muscle action potential and muscle tension studie...

D. G. Kline A. R. Hudson B. R. Bratton E. R. Hackett L. T. Happel



Amplitude of somatosensory cortical evoked potentials is correlated with spontaneous activity of spinal neurones in the cat  

Microsoft Academic Search

Simultaneous recordings of cortical evoked potentials in the posterior sigmoid gyrus, and spontaneous negative cord dorsum potentials (CDPs) of the L6 lumbar spinal segment, were made in the anaesthetised cat. The electrodes were positioned in cortical and spinal somatosensory regions where the largest spontaneous and evoked negative potentials were detected. Evoked potentials were produced by electrical stimulation to cutaneous nerves

E. Manjarrez; G. Rojas-Piloni; L. Mart??nez; D. Vázquez; D. Vélez; I. Méndez; A. Flores



Pedunculopontine nucleus evoked potentials from subthalamic nucleus stimulation in Parkinson's disease.  


The effects of subthalamic nucleus (STN) stimulation on the pedunculopontine nucleus area (PPNR) evoked activities were examined in two patients with Parkinson's disease. The patients had previously undergone bilateral STN deep brain stimulation (DBS) and subsequently received unilateral DBS electrodes in the PPNR. Evoked potentials were recorded from the local field potentials (LFP) from the PPNR with STN stimulation at different frequencies and bipolar contacts. Ipsilateral and contralateral short latency (<2ms) PPNR responses were evoked from left but not from right STN stimulation. In both patients, STN stimulation evoked contralateral PPNR responses at medium latencies between 41 and 45ms. Cortical evoked potentials to single pulse STN stimulation were observed at latencies between 18 and 27ms. These results demonstrate a functional connection between the STN and the PPNR. It likely involves direct projections between the STN and PPNR or polysynaptic pathways with thalamic or cortical relays. PMID:24095981

Neagu, Bogdan; Tsang, Eric; Mazzella, Filomena; Hamani, Clement; Moro, Elena; Hodaie, Mojgan; Lozano, Andres M; Chen, Robert



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

ERIC Educational Resources Information Center

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…

Izawa, Shuji; Mizutani, Tohru


Neural generators of early cortical somatosensory evoked potentials in the awake monkey  

Microsoft Academic Search

Controversy continues to exist regarding the generators of the initial cortical components of the somatosensory evoked potential (SEP). This issue was explored by detailed epidural and intracortical mapping of somatosensory evoked activity in Old World monkeys. In depth recordings, 3 complementary procedures were utilized: (1) the intracortical and subcortical distribution of SEPs was determined from approximately 4000 locations; (2) concomitant

Nancy Nicholson Peterson; Charles E. Schroeder; Joseph C. Arezzo



Paying attention to orthography: a visual evoked potential study  

PubMed Central

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).

Herdman, Anthony T.; Takai, Osamu



Event related evoked potentials in dementia: role of vitamin E.  


Dementia is a common cognitive syndrome reflecting a wide spread chronic progressive disease as an extension to normal aging process. Oxidative stress has been implicated in dementia and antioxidants have become attractive therapeutic agents. Among the antioxidants vitamin E is the most potent in the treatment of dementia. Study was conducted in 20 patients suffering from dementia in the age group of 66-74 and in 20 age and sex matched controls. Latency of the P3 component of event related evoked potential (ERP) showed an increase from 338.65 +/- 42.22 msec in control group to 348.9 +/- 46.38 msec in patients of dementia. In control group P3 latency decreased from 338.65 +/- 42.22 msec to 331.6 +/- 38.75 msec after Vitamin E therapy. In patients of dementia latency decreased significantly from 348.9 +/- 46.38 msec to 324.62 +/- 44.25 msec after vitamin therapy for one month. P3 amplitude in controls and demented was 7.2 +/- 3.62 mu v and 7.07 +/- 3.73 mu v respectively. After vitamin E therapy a statistically significant increase in amplitude (P < 0.05) was observed in controls (9.34 +/- 5.04 mu v) and in patients of dementia (9.58 +/- 5.24 mu v). The study suggests that the latency and amplitude of P3 were not significantly different in control and dementia patients, while vitamin E supplementation (oral 800 mg per day for 30 days) decreased the latency and increased the P3 amplitude in both the control and dementia patients. Our study further supports that Vitamin E supplementation, because of its antioxidant property might be decreasing oxidative stress, which may lead to improvement in cognitive pool of generator neurons of P3. PMID:12024959

Vaney, Neelam; Chouhan, Sandeep; Bhatia, M S; Tandon, O P



Neural origin of evoked potentials during thalamic deep brain stimulation.  


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. PMID:23719207

Kent, Alexander R; Grill, Warren M



Somatosensory evoked potential monitoring following severe closed head injury.  


This paper describes the results of somatosensory evoked potential (SSEP) monitoring in 65 patients with severe head injury. Intracranial pressure (ICP) monitoring data were available for 63 patients, and arterial-jugular oxygen content (AVDO2) data for 52 patients. Eighty-nine percent of patients with no SSEP activity beyond 50 msec post-stimulus in either hemisphere died or were vegetative survivors (3 month Glasgow Outcome Score). All 17 patients with a good or moderate outcome had long latency cortical activity (i.e. > or = 70 msec post-stimulus) in both hemispheres. Among patients with absent activity in 1 hemisphere, 53% died and 47% were severely disabled (chi 2 = 40, p = 0.0000). In the latter group, age was a significant factor among patients who died or were severely disabled (p < 0.02). Forty-four of 65 patients had either clear-cut deterioration or improvement in SSEPs over the course of monitoring. There were no significant differences in peak ICP between patients with improving or deteriorating SSEPs. In contrast, those with deteriorating SSEPs had a significant drop in AVDO2, compared with patients with improving SSEPs (p < 0.01). Long-term continuous monitoring of SSEPs shows that following severe injury, neurologic function may undergo significant change in approximately two-thirds of patients. Furthermore, ICP does not appear to play a prominent role in neurologic deterioration. AVDO2 measurements indicate that deterioration is more likely associated with perturbation of cerebral oxidative metabolism. SSEP monitoring following severe head injury has proven prognostic value, and is recommended for patients who must be pharmacologically paralyzed for ICP or ventilator management. PMID:7923995

Moulton, R J; Shedden, P M; Tucker, W S; Muller, P J



Aging effect in pattern, motion and cognitive visual evoked potentials.  


An electrophysiological study on the effect of aging on the visual pathway and various levels of visual information processing (primary cortex, associate visual motion processing cortex and cognitive cortical areas) was performed. We examined visual evoked potentials (VEPs) to pattern-reversal, motion-onset (translation and radial motion) and visual stimuli with a cognitive task (cognitive VEPs - P300 wave) at luminance of 17 cd/m(2). The most significant age-related change in a group of 150 healthy volunteers (15-85 years of age) was the increase in the P300 wave latency (2 ms per 1 year of age). Delays of the motion-onset VEPs (0.47 ms/year in translation and 0.46 ms/year in radial motion) and the pattern-reversal VEPs (0.26 ms/year) and the reductions of their amplitudes with increasing subject age (primarily in P300) were also found to be significant. The amplitude of the motion-onset VEPs to radial motion remained the most constant parameter with increasing age. Age-related changes were stronger in males. Our results indicate that cognitive VEPs, despite larger variability of their parameters, could be a useful criterion for an objective evaluation of the aging processes within the CNS. Possible differences in aging between the motion-processing system and the form-processing system within the visual pathway might be indicated by the more pronounced delay in the motion-onset VEPs and by their preserved size for radial motion (a biologically significant variant of motion) compared to the changes in pattern-reversal VEPs. PMID:22503557

Kuba, Miroslav; Kremlá?ek, Jan; Langrová, Jana; Kubová, Zuzana; Szanyi, Jana; Vít, František



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).  


An evoked potential differs from the EEG mainly in two ways: 1. The EEG is a random, continuous signal, which arises from the ongoing activity of the outer layers of the cortex. An evoked potential is the brain's response to a repetitive stimulus along a specific nerve pathway. 2.EEG signals range from 10-200 milliVolt (mV). Evoked potentials are smaller in amplitude (1-5-20 microVolt requiring precise electrode positioning and special techniques (signal averaging) to extract the specific response from the underlying EEG "noise". The technique of signal averaging, as originally described by Dawson in 1954 [69J, has been further developed in computer processing. The technique is now used by applying a stimulus repeatedly--preferably at randomized intervals--and to record the evoked response over the corresponding area of the brain, averaging out mathematically the change over the number of stimuli. Rationale for the use of EPs in the OR and the ICU. Evoked potentials (EPs) serve the following major purposes: 1. Monitoring of the functional integrity of neural structures that may be at risk during, for instance, ECC (extracorporeal circulation) or endarterectomy indicating cerebral hypoxia. 2. Monitoring of the effects of anesthetic agents and other centrally active drugs, which, besides the cortex, affect deeper neuronal structures. 3. Orthopedic cases where the spinal cord is at risk such as Harrington rod insertion and removal. 4. Clamping of the abdominal aortic artery during aneurysmectomy resulting in a potential damage of the lower parts of the spinal cord. 5. Clipping of an intracerebral aneurysm, which may be impeding blood flow to vital cerebral textures. 6. An indicator of cerebral hypoxia when the blood pressure is deliberately lowered. 7. Operation on peripheral nerves and nerve roots to identify early trauma. 8. Monitoring the cerebral function during controlled hypothermia when the EEG becomes flat. 9. Monitoring of the pathophysiological conditions 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 neurologic disorders such as: a) multiple sclerosis, b) acoustic nerve tumors, a

Freye, Enno



Automatisation of a localising technique in aphasia based upon averaged evoked potentials.  


Averaged evoked potentials were utilised as a localising technique in aphasia. Based on a set of measurements extracted from various evoked potentials, subjects from four diagnostic categories were correctly classified in more than 70% of the cases. The measurements were derived from amplitudes and latencies of significant peaks which were selected by human judgement from plots of the recorded evoked potentials. An algorithm has been developed which simulates the manual procedure and reduces the processing time per patient by several magnitudes. The automated method yields results which are more consistent with expected results than those from the manual method. The percentage of correct classification is in both cases essentially the same. PMID:591123

Liedtke, C; Morley, G K



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

NASA Technical Reports Server (NTRS)

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.

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



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

PubMed Central

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 adults. CAEP latency-intensity input output functions were steeper in infants compared to adults. CAEP amplitude growth functions with respect to stimulus SPL are adult-like at this age, particularly for the earliest component, P1-N1. Infant perceptual thresholds were elevated with respect to those found in adults. Furthermore, perceptual thresholds were higher, on average, than levels at which CAEPs could be obtained. When CAEP amplitudes were plotted with respect to perceptual threshold (dB SL), the infant CAEP amplitude growth slopes were steeper than in adults. Conclusions Although CAEP latencies indicate immaturity in neural transmission at the level of the cortex, amplitude growth with respect to stimulus SPL is adult-like at this age, particularly for the earliest component, P1-N1. The latency and amplitude input-output functions may provide additional information as to how infants perceive stimulus level. The reasons for the discrepancy between electrophysiologic and perceptual threshold may be due to immaturity in perceptual temporal resolution abilities and the broad-band listening strategy employed by infants. The findings from the current study can be translated to the clinical setting. It is possible to use tonal or speech sound tokens to evoke CAEPs in an awake, passively alert infant, and thus determine whether these sounds activate the auditory cortex. This could be beneficial in the verification of hearing aid or cochlear implant benefit.

Cone, Barbara; Whitaker, Richard



Chromatic visual evoked potentials in young patients with demyelinating disease.  


The purpose of this study was to evaluate color vision in young patients with demyelinating disease both clinically and electrophysiologically. Thirty young patients (8-28 years, mean age 19 years) with demyelinating disease with or without a history of optic neuritis (ON) were investigated. Color vision was evaluated clinically with the Ishihara test and the Farnsworth-Munsell 100 hue (FM 100 hue) test and electrophysiologically with chromatic visual evoked potentials (cVEPs). Color deficiency axis and error score (ES) obtained with the FM 100 hue test were analyzed. cVEPs to isoluminant red-green (R-G) and blue-yellow (B-Y) stimuli were recorded. The stimulus was a 7 deg circle composed of horizontal sinusoidal gratings with a spatial frequency of 2?cycles/deg and 90% chromatic contrast. Onset-offset mode of stimulation (ON:OFF=300?700??ms) was used. Since the majority of the patients were adults (>18??years), the negative wave (N wave) of the cVEP respones is the prominent part and therefore was analyzed. Sixty eyes were studied-22 with at least one episode of ON (ON group) and 38 without any clinically evident episode of ON (nON group). The average ES in the ON group was 179.18±171.8, whereas in the nON group it was 87.60±65.34. The average N-wave latency in the ON group was 144±44??ms for the R-G stimulus and 146±56??ms for the B-Y stimulus, whereas in the nON group, it was 117±13??ms for the R-G stimulus and 121±22??ms for the B-Y one. The average N-wave amplitude in the ON group was 9.3±7.1???V for the R-G stimulus and 5.1±3.9???V for the B-Y one, whereas in the nON group, it was 10.8±8.3???V for the R-G stimulus and 6.4±4.3???V for the B-Y one. A significant difference between the ON and the nON group was found: in the ON group, ES was higher (p=0.01) and N-wave latency was longer (p=0.01) compared with those in the nON group. The study showed that color vision is expectedly more affected in the ON group, but also often in the nON group, which may indicate increased parvocellular visual pathway vulnerability in demyelinating diseases. PMID:24695207

Pompe, Manca Tekav?i?; Brecelj, Jelka; Kranjc, Branka Stirn



Auditory evoked potential development in early childhood: a longitudinal study.  


Serial recordings of auditory evoked potentials (AEPs) to clicks were obtained using a vertex-mastoid derivation from 16 normal children during sleep over an age span from near birth to age 3. The AEP components studied were: N0 (38 +/- 10 msec), P1 (79 +/- 24 msec), N1 (109 +/- 39 msec), P2 (186 +/- 35 msec), N2 (409 +/- 97 msec), P3A (554 +/- 116 msec), P3B (757 +/- 121 msec) and P3 (728 +/- 128 msec). Amplitudes and latencies of the components were calculated and regressions of the measures on age were computed for the group as a whole, for each subject and for subsets of the data based on sleep stage, sex, order of stimulus presentation and a rearing/race factor. For the group as a whole the latencies of P1, P2, P3, and P3B decreased with age. The amplitudes of P1N1 and the N2P3 waves increased with age. Most change occurred during the first year of life. In general, the changes with age were also found to hold across all of the factors examined, although individuals varied widely in the degree to which they conformed to the trends found for the data as a whole. The amount contributed by each of the factors mentioned above to the total variance was estimated. The proportions varied for different EP components but, in general, age, sleep state, and subject factors other than rearing/race and sex accounted for most variance. One half to 5/6 of the unexplained variance in AEP latencies and amplitudes (i.e., that not due to age, sleep state, etc.) occurred across rather than within subjects. For both the group as a whole and for individual children, P2 and N2 latencies were found to exhibit the greatest stability across time. The results of the longitudinal study reported here were in good agreement with those of a previous study from this laboratory which utilized a cross-sectional design. PMID:76550

Ohlrich, E S; Barnet, A B; Weiss, I P; Shanks, B L



Plasticity of First-Order Sensory Synapses: Interactions between Homosynaptic Long-Term Potentiation and Heterosynaptically Evoked Dopaminergic Potentiation  

Microsoft Academic Search

Persistent potentiations of the chemical and electrotonic com- ponents of the eighth nerve (NVIII) EPSP recorded in vivo in the goldfish reticulospinal neuron, the Mauthner cell, can be evoked by afferent tetanization or local dendritic application of an endogenous transmitter, dopamine (3-hydroxytyramine). These modifications are attributable to the activation of distinct intracellular kinase cascades. Although dopamine-evoked po- tentiation (DEP) is

Sanjay S. Kumar; Donald S. Faber




EPA Science Inventory

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


Cervical vestibular evoked myogenic potentials (cVEMPs) in patients with superior canal dehiscence syndrome (SCDS)  

Microsoft Academic Search

ObjectiveTo determine the usefulness of both amplitude and threshold data from tone-burst cervical vestibular evoked myogenic potential (cVEMP) testing for the evaluation of superior canal dehiscence syndrome (SCDS).

Rachel E. Roditi; Robert W. Eppsteiner; Todd B. Sauter; Daniel J. Lee



Monoamine Oxidase Inhibition Cannot Account for Changes in Visual Evoked Potentials Produced by Chlordimeform.  

National Technical Information Service (NTIS)

Chlordimeform (CDM), a formamidine insecticide and monoamine oxidase (MAO) inhibitor, has recently been shown to produce profound changes in visual evoked potentials of hooded rats (Dyer and Boyes, The Toxicologist, 3: 13, 1983). Two experiments were perf...

W. K. Boyes V. C. Moser R. C. MacPhail R. S. Dyer



Investigation of brachial plexus traction lesions by peripheral and spinal somatosensory evoked potentials  

Microsoft Academic Search

Peripheral, spinal and cortical somatosensory evoked potentials were recorded in 26 patients with unilateral traction injuries of the brachial plexus ganglia. Of 10 cases explored surgically the recordings correctly anticipated the major site of the lesion in eight.

S J Jones



Evoked Potentials in Immobilized Cats to a Combination of Clicks with Painful Electrocutaneous Stimuli.  

National Technical Information Service (NTIS)

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 numb...

M. A. Gilinskiy I. A. Korsakov



Vergleichende Untersuchung somatosensibler spinaler und kortikaler Evoked Potentials bei Kindern  

Microsoft Academic Search

Somatosensory spinal (spinEP) and primary cortical evoked responses (ssEP) to median and tibial nerve stimulation (at forefinger, wrist, and ankle respectively) were investigated by means of summation techniques in 23 normal children aged 6 to 14 years. Amplitude recovery functions of cervical spinEP were tested by paired stimuli and short tetanic stimulation at the wrist: spinEP amplitudes were unchanged for

Manfred Sauer; Eduard Schenck



Multimodal evoked potentials to assess the evolution of multiple sclerosis: a longitudinal study  

PubMed Central

Background Evoked potentials are used in the functional assessment of sensory and motor pathways. Their usefulness in monitoring the evolution of multiple sclerosis has not been fully clarified. Objective The aim of this longitudinal study was to examine the usefulness of multimodal evoked potential in predicting paraclinical outcomes of disease severity and as a prognostic marker in multiple sclerosis. Methods Eighty four patients with clinically definite multiple sclerosis underwent Expanded Disability Status Scale (EDSS) and functional system scoring at study entry and after a mean (standard deviation) follow?up of 30.5 (11.7)?months. Sensory and motor evoked potentials were obtained in all patients at study entry and at follow?up in 64 of them, and quantified according to a conventional score. Results Cross?sectionally, the severity of each evoked potential score significantly correlated with the corresponding functional system (0.32evoked potential) and with EDSS (0.34evoked potential). EDSS significantly correlated with global evoked potential score severity (baseline R?=?0.60, follow?up R?=?0.46, p<0.001). Using longitudinal analysis, only changes in somatosensory evoked potential scores were significantly correlated with changes of sensory functional system (R?=?0.34, p?=?0.006). However, patients with multiple sclerosis with disability progression at follow?up had more severe baseline evoked potential scores than patients who remained stable. Patients with severe baseline global evoked potential score (higher than the median value) had a risk of 72.5% to progress on disability at follow?up, whereas patients with multiple sclerosis with lower scores had a risk of only 36.3%. Conclusions These results suggest that evoked potential is a good marker of the severity of nervous damage in multiple sclerosis and may have a predictive value regarding the evolution of disability.

Leocani, L; Rovaris, M; Boneschi, F M; Medaglini, S; Rossi, P; Martinelli, V; Amadio, S; Comi, G



Effects of repetitive transcranial magnetic stimulation on visual evoked potentials in migraine  

Microsoft Academic Search

Summary Between attacks, migraine patients are characterized by potentiation instead of habituation of stimulation- evoked cortical responses. It is debated whether this is due to increased or decreased cortical excitability. We have studied the changes in visual cortex excitabil- ity by recording pattern-reversal visual evoked potentials (PR-VEP) after low- and high-frequency repetitive transcranial magnetic stimulation (rTMS), known respectively for their

V. Bohotin; A. Fumal; M Vandenheede; P. Gerard; C. Bohotin; A. Maertens de Noordhout; J. Schoenen



Somatosensory and motor-evoked potential monitoring during spine and spinal cord surgery  

Microsoft Academic Search

Study design:Prospective, observational study.Setting:Regional Trauma Center, Torino, Italy.Objectives:Complex spinal surgery carries a significant risk of neurological damage. The aim of this study is to determine the reliability and applicability of multimodality motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs) monitoring during spine and spinal cord surgery in our institute.Methods:Recordings of MEPs to multipulse transcranial electrical stimulation (TES) and cortical SEPs were

P Costa; A Bruno; M Bonzanino; F Massaro; L Caruso; I Vincenzo; P Ciaramitaro; E Montalenti



Intraoperative monitoring of sensory evoked potentials may be neither a proven nor an indicated technique  

Microsoft Academic Search

Excluding specific neurosurgical indications for cortical localization or peripheral nerve surgery, the use of sensory evoked\\u000a potentials as a monitor in the operating room should be controversial at this time. Whether appropriate or not, legal and\\u000a medical forces have largely established the use of somatosensory evoked potential monitoring as a standard during procedures\\u000a that threaten the integrity of the spinal

John D. Michenfelder



Motor-evoked potentials in a child recovering from transverse myelitis  

Microsoft Academic Search

We describe a 13-year-old female, with an inability to walk because of transverse myelitis, who demonstrated progressive recovery of both motor function and motor- evoked potentials (MEP). At 4 weeks after onset, amplitudes of MEP were decreased, latencies were prolonged, and cortical somatosensory-evoked potentials (SEP) were absent. At 6 and 12 weeks, MEP revealed progressively higher amplitudes and shorter latencies.

Yukio Noguchi; Osami Okubo; Tatsuo Fuchigami; Yukihiko Fujita; Kensuke Harada



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

Microsoft Academic Search

The present study aimed to evaluate heat pain thresholds and evoked potentials following CO2 laser thermal stimulation (laser-evoked potentials, LEPs), during remote application of capsaicin, in migraine patients vs.\\u000a non-migraine healthy controls. Twelve outpatients suffering from migraine without aura were compared with 10 healthy controls.\\u000a The LEPs were recorded by 6 scalp electrodes, stimulating the dorsum of the right hand

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



Monitoring of sensory evoked potentials is highly reliable and helpful in the operating room  

Microsoft Academic Search

Because short-latency evoked potentials are relatively resistant to anesthetic agents, they can be used to monitor neural\\u000a pathways during surgical procedures. The use of median nerve somatosensory evoked potentials to localize the central sulcus\\u000a is an established aid of indisputable value in neurosurgical procedures involving cortical incisions for resection of certain\\u000a epileptic foci, vascular malformations, or neoplasms near the central

William A. Friedman; Betty L. Grundy



Evoked potential studies in the antiphospholipid syndrome: differential diagnosis from multiple sclerosis  

PubMed Central

Background The CNS manifestations of the antiphospholipid syndrome (APS) can mimic multiple sclerosis both clinically and radiologically. Objective To compare evoked potential studies in APS patients and patients with multiple sclerosis with similar neurological disability. Methods 30 APS patients with CNS manifestations and 33 patients with definite multiple sclerosis and similar neurological disability underwent studies of visual evoked potentials (VEP), somatosensory evoked potentials (SSEP) in the upper and lower limbs (UL, LL), and sympathetic skin responses (SSR) in the upper and lower limbs. Results The neurological manifestations in the APS patients included stroke (n?=?17), transient ischaemic attacks (n?=?10), and severe headache with multiple white matter lesions on brain MRI (n?=?3). Abnormal SSEP (LL), and SSR (UL; LL) were seen in APS patients (37%, 27%, and 30%, respectively) but VEP and UL SSEP were rarely abnormal (10% and 6%, respectively in APS v 58% and 33% in multiple sclerosis; p?=?0.0005, p?=?0.008). Mean VEP latencies were more prolonged in multiple sclerosis (116?ms v 101?ms, p<0.001). Only one APS patient had abnormal findings in all three evoked potential studies, compared with seven patients in the multiple sclerosis group (p?=?0.04) Conclusions Abnormal VEPs are uncommon in APS in contrast to multiple sclerosis. Coexisting abnormalities in all other evoked potentials were similarly rare in APS. In patients with brain MRI findings compatible either with multiple sclerosis or APS, normal evoked potential tests, and especially a normal VEP, may support the diagnosis of APS.

Paran, D; Chapman, J; Korczyn, A D; Elkayam, O; Hilkevich, O; Groozman, G B; Levartovsky, D; Litinsky, I; Caspi, D; Segev, Y; Drory, V E



Evaluation of intraoperative somatosensory-evoked potential monitoring during 100 cervical operations.  


Continuous intraoperative somatosensory-evoked potential monitoring during scoliosis surgery, along with improved instrumentation techniques, has contributed to the reduction of neurologic injury from 4-6.9% to 0-0.7%. To assess whether somatosensory-evoked potential monitoring might play a similar role in cervical surgery, the authors compared the morbidity and mortality rates associated with 218 patients who were not monitored and were operated on between 1985-1989 with those found in 100 consecutive somatosensory-evoked potential monitored procedures done from 1989-1991. The cervical procedures were conducted for disc disease, stenosis, spondylosis, and ossification of the posterior longitudinal ligament. Eight of 218 unmonitored patients became quadriplegic (3.7%) and 1 died (0.5%); no instances of quadriplegia and no deaths were encountered among the 100 monitored patients. The reduction of neurologic deficit was attributed in part to early somatosensory-evoked potential detection of vascular or mechanical compromise of the spinal cord or nerve roots and to the immediate alteration of anesthetic or surgical technique in response to somatosensory-evoked potential changes, i.e., reversal of systemic or "relative" hypotension, adjustment of operative position, release of distraction, and cessation of manipulation. Continuous intraoperative somatosensory-evoked potential monitoring also was a practical tool in monitoring cervical surgery. PMID:8516704

Epstein, N E; Danto, J; Nardi, D



The clinical role of somatosensory evoked potential studies: a critical appraisal.  


The clinical utility and limitations of somatosensory evoked potential (SEP) studies are reviewed. Somatosensory evoked potentials may help to identify a lesion in the sensory pathways, but do not indicate its nature. In multiple sclerosis subjects, the SEP findings may help to establish that there is a multiplicity of lesions, but multimodality evoked potential abnormalities may occur in other disorders. Somatosensory evoked potential abnormalities do not reflect either the severity or the prognosis of cervical spondylosis and do not reliably permit early recognition of the totality of traumatic cord lesions, while the role of SEPs in monitoring cord function intraoperatively awaits definition. Somatosensory evoked potentials do not reliably indicate the individual prognosis after severe head injury, and discrepancies in published findings suggest that their use in the evaluation of brain death is premature. In hereditary spinocerebellar degenerations, SEP abnormalities may reflect central or peripheral pathology. Somatosensory evoked potentials can be used to determine conduction velocity in peripheral nerves and to identify inaccessible proximal lesions of these nerves, but the findings may lead to misleading conclusions about brachial plexus lesions, especially if pre- and postganglionic lesions coexist. PMID:6330546

Aminoff, M J



Potentiation by cadmium ion of ATP-evoked dopamine release in rat phaeochromocytoma cells.  

PubMed Central

1. The effects of cadmium ion (Cd2+) on release of dopamine and on an inward current evoked by extracellular ATP were investigated in rat phaeochromocytoma PC12 cells. 2. Cd2+ (100 microM-3 mM) potentiated the dopamine release evoked by 30 microM ATP from the cells. Cd2+ (100 microM) shifted the concentration-response curve of ATP-evoked dopamine release to the left without affecting the maximal response. 3. Suramin (30 microM) completely abolished the dopamine release evoked by 30 microM ATP but only partially inhibited the release evoked by 100 microM ATP consistent with its role as a competitive antagonist. The response evoked by 30 microM ATP in the presence of Cd2+ (300 microM) was comparable to that observed with 100 microM ATP alone; however, only the former was almost completely inhibited by suramin. 4. Cd2+ (100 microM) potentiated an inward current activated by 30 microM ATP alone. A higher concentration of Cd2+ (300 microM) had a smaller effect on amplitude potentiation but significantly prolonged the duration of the current. 5. The time-course of the ATP-evoked dopamine release was investigated using a real-time monitoring system for dopamine release. Although Cd2+ (300 microM) had little effect on the time-course of activation the ATP-evoked dopamine release, it produced a long-lasting dopamine release which slowly returned to the baseline. 6. Taken together, these observations suggest that Cd2+ enhances ATP-evoked dopamine release by affecting P2-purinoceptor/channels. The enhancement may be attributed to a Cd(2+)-dependent increase in sensitivity to ATP.

Ikeda, M.; Koizumi, S.; Nakazawa, K.; Inoue, K.; Ito, K.; Inoue, K.



Gustatory hedonic value: Potential function for forebrain control of brainstem taste processing  

PubMed Central

Among well-nourished populations, eating beyond homeostatic needs when presented with caloric-dense palatable food evidences the assertion that an increasing proportion of consumption is driven by pleasure, not just by the need for calories. This presents a major health crisis because the affective component of foods constitutes a behavioral risk factor that promotes over consumption [Sorensen, L.B., Moller, P., Flint, A., Martens, M., Raben, A., 2003. Effect of sensory perception of foods on appetite and food intake: a review of studies on humans. Int. J. Obes. Relat. Metab. Disord. 27, 1152–1166; Yeomans, M.R., Blundell, J.E., Leshem, M., 2004. Palatability: response to nutritional need or need-free stimulation of appetite? Br. J. Nutr. 92 (Suppl. 1), S3–S14]. Overweight or obese individuals have an increased risk of developing hypertension, stroke, heart disease, chronic musculoskeletal problems, type-2 diabetes, and certain types of cancers [Hill, J.O., Catenacci, V., Wyatt, H.R., 2005. Obesity: overview of an epidemic. Psychiatr. Clin. N. Am. 28, 1–23, vii]. The etiology of obesity is complex involving genetic, metabolic, and behavioral factors, but ultimately results from long-term energy imbalance. Evidence indicates that learned and some forms of unlearned control of ingestive behavior driven by palatability (i.e. hedonic value) are critically dependent on reciprocal interactions between brainstem gustatory nuclei and the ventral forebrain. This review discusses the current understanding of centrifugal control of taste processing in subcortical gustatory nuclei and the potential role of such modulation in hedonic responding.

Lundy, Robert F.



Midlatency auditory evoked potentials and the startle response in the rat  

Microsoft Academic Search

The P13 midlatency auditory evoked potential in the rat is (i) sleep state dependent, (ii) undergoes rapid habituation and (iii) is blocked by the cholinergic antagonist scopolamine. As such, the P13 potential in the rat shows the same characteristics as the P1 (or P50) potential in the human. These potentials are thought to be mediated, at least in part, by

H Miyazato; R. D Skinner; N. B Reese; J Mukawa; E Garcia-Rill



Identification of central auditory processing disorders by scale and entropy features of binaural auditory brainstem potentials  

Microsoft Academic Search

The ?-wave of the binaural interaction component in auditory brainstem responses has been suggested as an objective measure of binaural interaction and has been shown to be of diagnostic value in the diagnosis of the central auditory processing disorder (CAPD). However, a reliable and automated detection of the ?-wave capable of clinical use still remains a challenge. In this correspondence,

D. J. Strauss; W. Delbl; P. K. Plinkert



Effects of Glutamate Receptor Agonists on the P13 Auditory Evoked Potential and Startle Response in the Rat  

PubMed Central

The P13 potential is the rodent equivalent of the P50 potential, which is an evoked response recorded at the vertex (Vx) 50?ms following an auditory stimulus in humans. Both the P13 and P50 potentials are only present during waking and rapid eye movement (REM) sleep, and are considered to be measures of level of arousal. The source of the P13 and P50 potentials appears to be the pedunculopontine nucleus (PPN), a brainstem nucleus with indirect ascending projections to the cortex through the intralaminar thalamus, mediating arousal, and descending inhibitory projections to the caudal pontine reticular formation (CPRF), which mediates the auditory startle response (SR). We tested the hypothesis that intracranial microinjection (ICM) of glutamate (GLU) or GLU receptor agonists will increase the activity of PPN neurons, resulting in an increased P13 potential response, and decreased SR due to inhibitory projections from the PPN to the CPRF, in freely moving animals. Cannulae were inserted into the PPN to inject neuroactive agents, screws were inserted into the Vx in order to record the P13 potential, and electrodes inserted into the dorsal nuchal muscle to record electromyograms and SR amplitude. Our results showed that ICM of GLU into the PPN dose-dependently increased the amplitude of the P13 potential and decreased the amplitude of the SR. Similarly, ICM of N-methyl-d-aspartic acid or kainate into the PPN increased the amplitude of the P13 potential. These findings indicate that glutamatergic input to the PPN plays a role in arousal control in vivo, and changes in glutamatergic input, or excitability of PPN neurons, could be implicated in a number of neuropsychiatric disorders with the common symptoms of hyperarousal and REM sleep dysregulation.

Simon, Christen; Wallace-Huitt, Tiffany; Thapa, Priyenka; Skinner, Robert D.; Garcia-Rill, Edgar



Monitoring of Motor Evoked Potentials with High Intensity Repetitive Transcranial Electrical Stimulation during Spinal surgery  

Microsoft Academic Search

Objective.Clinical utility of high voltage repetitive transcranial electrical stimulation (TES) was investigated in 46 patients undergoing spine surgery. Methods.During spinal surgery, motor evoked potentials (MEPs) were recorded from upper or lower limb muscles following high voltage repetitive TES of motor cortex under propofol and opioid\\/N2O anesthesia. Results.The number of responses evoked by the double pulse stimulation was significantly higher than

Siavash S. Haghighi



Evoked potential measurement of the masked hearing threshold of a Pacific white-sided dolphin (Lagenorhynchus obliquidens)  

NASA Astrophysics Data System (ADS)

The masked hearing threshold of a Pacific white-sided dolphin (Lagenorhynchus obliquidens) was determined by measuring the animal's auditory brainstem response (ABR). The dolphin was trained to wear surface-contact electrodes embedded in suction cups and to swim into a hoop centered at 1 m below the water surface facing a sound projector 5 m away. Broadband transient signals with center frequencies of 8, 16, 32, 64, 80, and 100 kHz were used as the stimuli. ABR signals were measured by digitizing the electrode signals in 32 point blocks at a sampling rate of 20 kHz. Five hundred blocks were averaged in order to obtain an ABR. The response latency for suprathreshold threshold signals was approximately 1.9 ms with the highest peak-to-peak ABR amplitude of approximately 2.8 uV occurring for a signal frequency of 64 kHz. The spectrum of the ABR signal was similar to that of Tursiops truncatus, with a major peak at 1120 Hz and a secondary peak at 664 Hz. Threshold was determined by progressively reducing the amplitude of the stimulus until an evoked potential could not be detected. The energy signal-to-noise ratio within an integration window at threshold varied between 1 and 8 dB.

Au, Whitlow W. L.; Jeanette, Thomas; Western, A.; Rameriz, Kenneth M.



Diffuse noxious inhibitory control. Reappraisal by pain-related somatosensory evoked potentials following CO2 laser stimulation.  


The effects of DNIC (diffuse noxious inhibitory control) in humans were evaluated by means of pain SEPs (somatosensory evoked potentials) and pain visual analogue scale (VAS) following CO2 laser stimulation applied to the left knee while conditioning stimuli (non-noxious and noxious thermal stimuli) applied to the right hand. Pain SEPs were recorded from scalp electrodes following laser stimulation applied to the left knee during various conditions as follows: (1) control (without any interference), (2) non-noxious (dipping the right hand in water at 41 degrees C for 3 min), (3) noxious (dipping the right hand in water at 46 degrees C for 3 min), and (4) after-effect (3-6 min after taking the hand from the water at 46 degrees C). The present pain SEPs findings confirmed the presence of DNIC in humans, and indicates: (1) degree of pain relief was significantly correlated with changes in pain SEPs, particularly a marked decrease in amplitude, and a decrease in VAS; (2) DNIC was more effective on the second pain than the first pain; (3) the effect of DNIC gradually increased over time, but it rapidly disappeared after the conditioning stimuli ceased; and (4) DNIC was not due merely to changes of attention. I propose that the site responsible for DNIC is the brainstem or the spinal cord rather than the cerebral hemisphere. PMID:7807168

Kakigi, R



Binaural interaction in specific language impairment: an auditory evoked potential study.  


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 impairment (SLI). Binaural interaction components (BICs) in the brainstem were compared in 19 children with SLI (13 males, six females; age range 7y 4mo-11y 10mo; mean age 9y 7mo [SD 1y 2mo]), and 31 comparison children with typical language development (16 males, 15 females; age range 7y 1mo-11y 4mo; mean age 9y 7mo [SD 1y 5mo]). Children with SLI had a significantly smaller BIC amplitude than the comparison group. However, no clear relationship was found between BIC measures and severity of language impairment. We conclude that, for some children, SLI may be associated with reduced binaural interaction which may hinder the detection or localization of speech sounds from noisy contexts during critical periods of language acquisition. PMID:17376138

Clarke, Elaine M; Adams, Catherine



Potential role for imidazole in the rhythmic respiratory activity of the in vitro neonatal rat brainstem  

Microsoft Academic Search

We used the imidazole-binding agent, diethylpyrocarbonate (DEPC), to test the hypothesis that rhythmic respiratory activity of the in vitro neonatal rat brainstem-spinal cord preparation was functionally dependent on imidazole. Neural activity was recorded from spinal nerves (C1-C4) during superfusion with 95%O2\\/5%CO2 buffer at pH 7.3 and T=26°C. Superfusate containing DEPC (40 mM) caused cessation of rhythmic activity within minutes. In

William L Krause; Homayoun Kazemi; Melvin D Burton



The slow-brainstem syndrome: tinnitus and dyssynchrony in the central nervous system.  


Among older patients we regularly find those who complain of a hazy tinnitus in combination with vertigo, giddiness, and dizziness. They also report a reduced state of alertness. Objectively, these patients exhibit an increase in latencies of experimentally evoked vestibular nystagmus and of auditory brainstem-evoked potentials. This group of patients is affected by the disorder known as slow-brainstem syndrome. By evaluating therapeutic responses, we noted especially in this group that a combination of cocculus (picrotoxin), conium (Coniine), amber, and petroleum (Vertigoheel) has a "tune-up" effect on the brainstem. With regular therapy using this drug regimen, we observed a normalization of the distorted latencies of the statoacoustic pathways, followed by disappearance of the symptoms. Our explanation for this phenomenon suggests an improvement in the vestibular, ocular, and acousticocortical pathway synchronization in such older patients. We present some models. PMID:18229789

Claussen, Claus F



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


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

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



An indirect component in the evoked compound action potential of the vagal nerve  

NASA Astrophysics Data System (ADS)

The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the brain stem or coming via the neural network on the heart. In an experimental study of 15 pigs, we identified four components in the evoked compound action potentials. The fourth component was found to be an indirect component, which came from the periphery. The latency of the indirect component increased when heart rate and contractility were decreased by burst stimulation (P = 0.01; n = 7). When heart rate and contractility were increased by dobutamine administration, the latency of the indirect component decreased (P = 0.01; n = 9). This showed that the latency of the indirect component of the evoked compound action potentials may relate to the state of the cardiovascular system.

Ordelman, Simone C. M. A.; Kornet, Lilian; Cornelussen, Richard; Buschman, Hendrik P. J.; Veltink, Peter H.



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

PubMed Central

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.

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



A personal computer-based visual evoked potential stimulus and recording system.  


A system for recording electroretinograms and visual evoked cortical potentials has been constructed with the use of a personal computer and a digital signal processing card. The system is based on widely available commercial hardware. It has been designed to be capable of performing routine visual electrophysiology as well as allowing the development of novel visual stimuli and signal detection techniques. The system enables both transient and steady-state stimulation rates. Pattern stimuli can be presented in pattern-reversal, pattern-onset, pattern-offset or motion-onset modes. In addition to conventional signal averaging, the digital signal processing card can also provide on-line Fourier analysis and is facilitating the development of adaptive filtering techniques for the detection of steady-state visual evoked cortical potentials. This versatile system is in regular clinical use for the measurement of electroretinograms and visual evoked cortical potentials. PMID:7956688

Bradnam, M S; Evans, A L; Montgomery, D M; Keating, D; Damato, B E; Cluckie, A; Allan, D



Modulation of motor evoked potentials by muscle vibration: the role of vibration frequency.  


Augmentation of motor evoked potentials (MEPs) by muscle vibration (MV) was studied in 10 healthy subjects with regard to the vibration frequency (VF). The extensor carpi radialis muscle (ECR) was vibrated using VFs of 80, 120, and 160 Hz. Motor evoked potentials following transcranial magnetic stimulation were recorded simultaneously from the vibrated ECR and the antagonist flexor carpi radialis muscle (FCR) without MV, 0.5 s and 3 s after onset of MV and 1 s after offset. Only the VFs of 80 Hz and 120 Hz caused MEP augmentation and latency shortening in ECR, whereas depression of MEPs in FCR was induced by all VFs used. It appears that MEP augmentation and latency shortening in ECR are mediated by the primary muscle spindle endings which respond with optimal discharge rates to VFs of up to 100 Hz. Motor evoked potential depression in FCR, being well expressed also with VF 160 Hz, seems to involve other dynamic mechanoreceptors. PMID:10514232

Siggelkow, S; Kossev, A; Schubert, M; Kappels, H H; Wolf, W; Dengler, R



Click-evoked responses from the cochlear nucleus: a study in human.  


Recordings from the vicinity of the cochlear nucleus in 9 patients undergoing microvascular decompression operations to relieve hemifacial spasm, trigeminal neuralgia, tinnitus, and disabling positional vertigo were conducted by placing a monopolar electrode in the lateral recess of the fourth ventricle (through the foramen of Luschka), the floor of which is the dorsolateral surface of the dorsal cochlear nucleus. The click-evoked potentials recorded by such an electrode display a slow negative wave with a peak latency of about 6-7 msec on which several sharp peaks are superimposed. None of the peaks in the recordings from the vicinity of the cochlear nucleus coincided with any vertex-positive peaks of the brain-stem auditory evoked potentials. In recordings from the lateral aspect of the floor of the fourth ventricle near the cochlear nucleus 1 patient showed 2 positive peaks, the earliest of which had a latency close to that of peak II and the second of which had a latency close to the negative peak between peaks III and IV of the brain-stem auditory evoked potentials. There is a distinct negative peak in the responses recorded from the midline of the floor of the fourth ventricle, the latency of which is only slightly shorter than that of peak V of the brain-stem auditory evoked potentials, supporting earlier findings that the sharp tip of peak V of the brain-stem auditory evoked potentials is generated by the termination of the lateral lemniscus in the inferior colliculus. PMID:7514991

Møller, A R; Jannetta, P J; Jho, H D



Comparison of the effects of sevoflurane and propofol on cortical somatosensory evoked potentials  

Microsoft Academic Search

Background. Propofol (P) and sevoflurane (S) are potential anaesthetic agents if electro- physiological monitoring is required during spinal surgery. They allow rapid recovery and do not depress cortical somatosensory evoked potentials (SSEP) as much as other agents. The effects of these agents on SSEP have not been compared before. Methods. Twenty-four patients were allocated randomly to receive either S (n=12)

N. Boisseau; M. Madany; P. Staccini; G. Armando; F. Martin; D. Grimaud



Characteristic variation in evoked potential amplitude with changes in pacing stimulus strength.  


The evoked potential, the intracardiac signal generated by a pacing stimulus, shows promise as a sensor for rate-responsive pacing and automatic threshold determinations. Thus, it is important to understand factors that may alter the morphology of evoked potentials and affect accurate signal analysis. Using a computer-based pacing system emulator, stimuli at 2.5, 5.0 and 6.9 V were delivered to 12 patients through permanent bipolar pacing leads. At 2.5 V, the evoked potential amplitude measured -12.63 +/- 7.79 mV. When the pacing amplitude was increased to 5.0 and 6.9 V, the signal diminished in size or reversed in polarity, or both, averaging -0.83 +/- 7.82 mV and 0.64 +/- 7.0 mV, respectively (p less than 0.01 vs 2.5 V). Pacing at 2.5 V was performed in an additional 8 patients with temporary quadripolar electrode catheters. With the distal pole of the catheter as the cathode and the proximal 3 poles as a common anode, the evoked potential averaged -9.01 +/- 5.44 mV. With the proximal 2 poles of the catheter disconnected to make the anode equal in size and current density to the cathode, the evoked potential diminished to -0.94 +/- 11.27 mV (p less than 0.05). There is thus a decrease in the evoked potential at high stimulus amplitudes compared to that obtained at the cathodic threshold. This finding can be reproduced by manipulation of the size and current density of the anode, suggesting that anodal stimulation at the ring of permanent pacing leads may be responsible. PMID:2386117

Curtis, A B; Vance, F; Miller-Shifrin, K



Efficacy of transcranial motor-evoked myogenic potentials to detect spinal cord ischemia during operations for thoracoabdominal aneurysms  

Microsoft Academic Search

Objective: Motor-evoked myogenic potentials after transcranial electrical stimulation monitor the vulnerable motoneuronal system of the spinal cord. This study reports our initial experiences with motor-evoked potentials to assess the adequacy of spinal cord perfusion during operations for thoracoabdominal aneurysms. Methods: In 20 patients undergoing thoracoabdominal aneurysm operations, myogenic motor-evoked potentials were recorded. In 18 patients retrograde aortic perfusion was used.

Peter de Haan; Cor J. Kalkman; Bas A. de Mol; Leon H. Ubags; Dirk J. Veldman; Michael J. H. M. Jacobs



Pattern reversal visual evoked potential among men at risk for alcoholism.  


The biological sons of male alcoholics, deemed to be at high risk (HR) for the development of alcoholism, were compared to control males, aged 18 to 21, using measures of the visual evoked potential elicited by checkerboard pattern reversal. Overall, the HR and control groups were not distinguished on the basis of visual evoked potential measures acquired from the occipital scalp region; however, when comparisons were restricted to right-handed subjects, the HR subjects showed more symmetry in a positive component with approximate latency of 242 ms compared with control subjects. The results are discussed in relation to hemispheric differences and alcoholism. PMID:3195352

Pollock, V E; Volavka, J; Gabrielli, W F; Mednick, S A; Knop, J; Goodwin, D W



Cannabinoid 1 and transient receptor potential vanilloid 1 receptors discretely modulate evoked glutamate separately from spontaneous glutamate transmission.  


Action potentials trigger synaptic terminals to synchronously release vesicles, but some vesicles release spontaneously. G-protein-coupled receptors (GPCRs) can modulate both of these processes. At cranial primary afferent terminals, the GPCR cannabinoid 1 (CB1) is often coexpressed with transient receptor potential vanilloid 1 (TRPV1), a nonselective cation channel present on most afferents. Here we tested whether CB1 activation modulates synchronous, action potential-evoked (eEPSCs) and/or spontaneous (sEPSCs) EPSCs at solitary tract nucleus neurons. In rat horizontal brainstem slices, activation of solitary tract (ST) primary afferents generated ST-eEPSCs that were rapidly and reversibly inhibited from most afferents by activation of CB1 with arachidonyl-2'-chloroethylamide (ACEA) or WIN 55,212-2 [R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl)(1-naphthalenyl) methanone monomethanesulfonate]. The CB1 antagonist/inverse agonist AM251 [N-1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide] blocked these responses. Despite profound depression of ST-eEPSCs during CB1 activation, sEPSCs in these same neurons were unaltered. Changes in temperature changed sEPSC frequency only from TRPV1(+) afferents (i.e., thermal sEPSC responses only occurred in TRPV1(+) afferents). CB1 activation failed to alter these thermal sEPSC responses. However, the endogenous arachidonate metabolite N-arachidonyldopamine (NADA) promiscuously activated both CB1 and TRPV1 receptors. NADA inhibited ST-eEPSCs while simultaneously increasing sEPSC frequency, and thermally triggered sEPSC increases in neurons with TRPV1(+) afferents. We found no evidence for CB1/TRPV1 interactions suggesting independent regulation of two separate vesicle pools. Together, these data demonstrate that action potential-evoked synchronous glutamate release is modulated separately from TRPV1-mediated glutamate release despite coexistence in the same central terminations. This two-pool arrangement allows independent and opposite modulation of glutamate release by single lipid metabolites. PMID:24920635

Fawley, Jessica A; Hofmann, Mackenzie E; Andresen, Michael C



The effects of interaction between large and small diameter fiber systems on the somatosensory evoked potential.  


The effect of interaction between large and small diameter fiber systems on the somatosensory evoked potential (SEP) was studied in anesthetized cats. Activation of large diameter fibers of the peroneal or radial nerves eliminates the late components of the SEP produced by stimulation of all fibers in the contralateral median or radial nerves. The inhibitory effects of a selective conditioning stimulus to the large diameter fibers of the peroneal nerve on the radial nerve evoked SEP was eliminated by bilateral transection of the dorsal column and spino-cervical tracts. However, interaction could still be obtained following transection when both large and small diameter fibers in the peroneal nerve were stimulated. The results of this study support the hypothesis that a correlation exists between activity in different fiber groups in afferent nerves, their conduction pathways through the cord, and the components of the cortical evoked potential. PMID:78821

Katz, S; Martin, H F; Blackburn, J G



Differing response properties of cervical and ocular vestibular evoked myogenic potentials evoked by air-conducted stimulation  

PubMed Central

Objective To determine the amplitude changes of vestibular evoked myogenic potentials (VEMPs) recorded simultaneously from the neck (cVEMPs) and eyes (oVEMPs) in response to 500 Hz, 2 ms air-conducted sound pips over a 30 dB range. Methods Fifteen healthy volunteers (mean age 29, range 18–57 years old) and one patient with unilateral superior canal dehiscence (SCD) were studied. The stimulus was reduced in increments to 105 dB pSPL for the normals (81 dB pSPL for the SCD patient). A statistical criterion was used to detect responses. Results Ipsilateral (i-p13/n23) and contralateral (c-n12/p24/n30) peaks for the cVEMP montage and contralateral (c-n10/p16/n21) and ipsilateral (i-n13) peaks for the oVEMP montage were present for the baseline intensity. For the lowest intensity, 6/15 subjects had responses for the i-p13 cVEMP potential and 4/15 had c-n10 oVEMP responses. The SCD patient showed larger responses for nearly all intensities. The cVEMP potentials were generally well fitted by a power law relationship, but the oVEMP c-n10, p16 and n21 potentials showed a significant increase in gradient for the higher intensities. Conclusion Most oVEMP and cVEMP responses follow a power law relationship but crossed oVEMP responses showed a change in gradient above a threshold. Significance The pattern of response to AC stimulation may be a property of the pathways underlying the potentials.

Dennis, Danielle L.; Govender, Sendhil; Chen, Peggy; Todd, Neil P. McAngus; Colebatch, James G.



Note on Cerebellar Evoked Potentials Related to Extraocular Muscle Stretch.  

National Technical Information Service (NTIS)

The studies of both Hermann and Wolfe, employing bipolar recordings in two different species (goldfish and cat), have demonstrated that there are slow cerebellar potentials related to saccadic eye movements, but they precede the saccades. This type of ana...

J. W. Wolfe



Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components  

NASA Astrophysics Data System (ADS)

Brain-computer interfaces (BCIs) can be realized on the basis of steady-state evoked potentials (SSEPs). These types of brain signals resulting from repetitive stimulation have the same fundamental frequency as the stimulation but also include higher harmonics. This study investigated how the classification accuracy of a 4-class BCI system can be improved by incorporating visually evoked harmonic oscillations. The current study revealed that the use of three SSVEP harmonics yielded a significantly higher classification accuracy than was the case for one or two harmonics. During feedback experiments, the five subjects investigated reached a classification accuracy between 42.5% and 94.4%.

Müller-Putz, Gernot R.; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert



Median nerve somatosensory evoked potential monitoring during carotid endarterectomy: does reference choice matter?  


Median nerve somatosensory evoked potential monitoring is commonly used during carotid endarterectomy to permit selective shunting in only those patients who are determined to have inadequate collateral flow after carotid cross-clamping. The N20 component is recorded from the CPc (contralateral centroparietal) electrode; either CPi (ipsilateral centroparietal) or Fpz (forehead) can be used as the reference. Because of the distribution of the subcortically generated N18 component, the CPc-Fpz derivation might record both the N20 and the N18 components and might therefore inadequately detect hemispheric ischemia after carotid cross-clamping. Somatosensory evoked potentials recorded were compared using these 2 derivations during 38 carotid endarterectomies to assess their ability to detect neurophysiologic changes after carotid cross-clamping. Although, as expected, the baseline N20 component was significantly larger when recorded with the CPc-Fpz derivation than with the CPc-CPi derivation (3.1 vs. 2.4 ?V in the hemisphere ipsilateral to the clamped carotid, P < 0.001), there was no significant difference in the postclamp amplitude decline between the 2 derivations (8.7% vs. 8.6%, P = 0.82). It is concluded that CPc-Fpz is an acceptable derivation for recording postclamp hemispheric somatosensory evoked potential changes during carotid endarterectomy and may be advantageous because it provides a larger amplitude somatosensory evoked potential than the CPc-CPi derivation. PMID:24492447

Fried, Stephen J; Smith, Diane M; Legatt, Alan D



Rat Flash-Evoked Potential Peak N160 Amplitude: Modulation by Relative Flash Intensity.  

National Technical Information Service (NTIS)

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

D. W. Herr W. K. Boyes R. S. Dyer




EPA Science Inventory

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


Source localisation of 62-electrode human laser pain evoked potential data using a realistic head model  

Microsoft Academic Search

Laser evoked potentials (LEPs), elicited by painful laser stimulation of the right forearm, were recorded from 62 electrodes in a single healthy subject. The positions of the electrodes on the scalp were co-registered with the subject's structural magnetic resonance image (MRI) of the brain. Spatio-temporal dipole modelling, using a head model derived from the MRI, estimated sources in left posterior

Deborah E. Bentley; Paula D. Youell; Alan R. Crossman; Anthony K. P. Jones



Intraoperative control by somatosensory evoked potentials in the treatment of cervical myeloradiculopathy. Results in 210 cases  

Microsoft Academic Search

Somatosensory evoked potentials (SEPs) were used for continuous monitoring of 210 patients during anterior surgery for cervical myeloradiculopathy, to test how effectively they help avoid irreversible neurological damage during surgery. The pathologies differed in severity and were treated by diskectomy or by extended corporectomy using the Senegas technique. Intraoperative SEP changes were recorded in 84 patients (40%); in 13 (6.2%)

C. Sebastifin; J. P. Raya; M. Ortega; E. Olalla; V. Lemos; R. Romero



Modulation of upper extremity motor evoked potentials by cutaneous afferents in humans  

Microsoft Academic Search

The excitability of motoneurons controlling upper limb muscles in humans may vary with cutaneous nerve stimulation. We investigated the effect of noxious and non-noxious conditioning stimuli applied to right and left digit II and right digit V on motor evoked potentials (MEPs) recorded from right thenar eminence, abductor digiti minimi, biceps and triceps brachii muscles in twelve healthy subjects. Transcranial

Markus Kofler; Peter Fuhr; A. Arturo Leis; Franz X Glocker; Martina F Kronenberg; Jörg Wissel; Ivana Stetkarova



Bilateral field advantage and evoked potential interhemispheric transmission in commissurotomy and callosal agenesis  

Microsoft Academic Search

The role of the corpus callosum versus other cerebral commissures in the interhemispheric integration of visual information was studied in four individuals with complete agenesis of the corpus callosum, two individuals with partial agenesis, one total commissurotomy patient, and normal individuals. Evoked potential (EP) indices of interhemispheric transmission of visual sensory responses were observed during matching of unilateral and bilateral

Warren S Brown; Malcolm A Jeeves; Rosalind Dietrich; Debra S Burnison



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

Microsoft Academic Search

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

M D Rugg; A D Milner; C R Lines



Unaltered respiratory-related evoked potentials after acute diaphragm dysfunction in humans  

Microsoft Academic Search

Respiratory muscles play an important role in the origin of respiratory sensations. Data dissecting the role of the diaphragm and other inspiratory muscles are scarce. This study aimed to determine the impact of diaphragm dysfunction following inspiratory resistive loading on respiratory-related evoked potentials considered as a neurophysiological substrate of certain types of respiratory sensations. Altogether, nine subjects aged 25-50 yrs

M. Bezzi; C. Donzel-Raynaud; C. Straus; C. Tantucciz; M. Zelter; J. P. Derenne; T. Similowski



A software system for recording and analyzing transient evoked potential data with an Apple IIe computer  

Microsoft Academic Search

The software package described here was designed to digitize transient evoked potential data from two chan­ nels simultaneously and to analyze the data using an Apple fie computerand a relatively inexpensive hardware configuration. Individual modules provide several data collection paradigms, a number of data analyses, and dis­ play capabilities. The system is capable of accommodat­ ing a variety of hardware

John A. Baro; Stephen Lehmkuhle



Usefulness of magnetic motor evoked potentials in the surgical treatment of hemiplegic patients with intractable epilepsy  

Microsoft Academic Search

Five hemiplegic patients with intractable epilepsy were studied with transcranial magnetic stimulation (TMS) before and after various surgical treatments. These patients had unilateral widespread cerebral lesions acquired at various times, including congenital, infantile and childhood injury. Motor evoked potentials (MEPs) of the abductor pollicis brevis (APB) muscles were simultaneously recorded on both sides following TMS of the motor cortex in




Evoked Potential Variability: Effects of Age, Amplitude and Methods of Measurement.  

National Technical Information Service (NTIS)

Visual and auditory evoked potentials (EPs) were recorded from 120 children of 6-15 years of age. EP variability was measured using a variety of techniques. All of these techniques showed that variability decreased with increasing age. Similar measures ap...

E. Callaway R. A. Halliday



Controlling a robot with a brain-computer interface based on steady state visual evoked potentials  

Microsoft Academic Search

In this paper a brain-computer interface (BCI) is presented which uses steady-state visual evoked potentials for controlling a robot. EEG is derived from three subjects to test the performance of the system. For feature extraction and classification on one hand the Minimum Energy method, and on the other hand the Fast Fourier Transformation (FFT) with linear discriminant analysis (LDA) is

Robert Prueckl; Christoph Guger



Electroencephalogram-Based Scaling of Multifocal Visual Evoked Potentials: Effect on Intersubject Amplitude Variability  

Microsoft Academic Search

PURPOSE. The interindividual variability of the visual evoked potential (VEP) has been recognized as a problem for interpre- tation of clinical results. This study examines whether VEP variability can be reduced by scaling responses according to underlying electroencephalogram (EEG) activity. METHODS. A multifocal objective perimeter provided different random check patterns to each of 58 points extending out to 32° nasally.

Alexander I. Klistorner; Stuart L. Graham



Evoked potentials and transcranial magnetic stimulation in migraine: published data and viewpoint on their pathophysiologic significance  

Microsoft Academic Search

Migraine is a disorder in which central nervous sytem dysfunction might play a pivotal role. Electroneurophysiology seems thus particularly suited to study its pathophysiology. We have extensively reviewed evoked potential and transcranial magnetic stimulation studies performed in migraineurs in order to identify their pathophysiologic significance. Publications available to us were completed by a Medline search. Retrieved and personal data were

Jean Schoenen; Anna Ambrosini; Peter S Sándor; Alain Maertens de Noordhout



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

Microsoft Academic Search

The human palm has a lower heat detection threshold and a higher heat pain threshold than hairy skin. Neurophysiological studies of monkeys suggest that glabrous skin has fewer low threshold heat nociceptors (AMH type 2) than hairy skin. Accordingly, we used a temperature-controlled contact heat evoked potential (CHEP) stimulator to excite selectively heat receptors with C fibers or A?-innervated AMH

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



Abnormal visual-evoked potentials in leukemic children after cranial radiation  

Microsoft Academic Search

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

Antonio Russo; Salvatore Tomarchio; Giuseppe Pero; Giuseppe Consoli; Roberto Marina; Carmelo Rizzari; G. Schiliro



Implementation of a microprocessor-based visual-evoked cortical potential recording and analysis system.  


An Imsai 8080 microcomputer is being used to simultaneously generate a color graphics stimulus display and to record visual-evoked cortical potentials. A brief description of the hardware and software developed for this system is presented. Data storage and analysis techniques are also discussed. PMID:7270657

Wilson, A; Fram, D; Sistar, J



Application of Factor Analytic Procedures to Complex Evoked Potential Measurements in Psychiatric Research  

Microsoft Academic Search

Several factor analytic procedures were applied to data gathered with a modified somatosensory evoked potential (SEP) recovery function prodecure in 56 non-patients and 224 psychiatric inpatients. The data were analyzed for each option reflected in three main issues. (1) Which group should be used for calculating the basic factor structure – normals only or all subjects? (2) Should measurements be

Richard A. Roemer; Charles Shagass; John J. Straumanis



The Effects of Dexmedetomidine on Myogenic Motor Evoked Potentials in Rabbits  

Microsoft Academic Search

BACKGROUND: Dexmedetomidine is used in the perioperative management of patients, including as an intraoperative adjuvant. The effects of dexmedetomidine on myogenic motor evoked potentials (MEPs) remain undetermined. We conducted the present study to investigate the effects of dexmedetomidine on myogenic MEPs in rabbits. METHODS: New Zealand white rabbits were used for the studies. First, to determine appropriate doses of dexmedetomidine

Yuri Yamamoto; Masahiko Kawaguchi; Meiko Kakimoto; Satoki Inoue; Hitoshi Furuya



Motor evoked potentials: appropriate positioning of recording electrodes for diagnosis of spinal disorders  

Microsoft Academic Search

The interpretation of normal and pathological findings of motor evoked potentials obtained by the use of transcranial magnetic stimulation depends on adequate examination technique, including the appropriate positioning of the recording electrodes over the muscle. On the basis of knowing the location of the motor end plate zones in muscles, magnetic stimulation of the motor cortex of 30 healthy adults

J. Chomiak; J. Dvorak; J. Antinnes; A. Sandler



Clinical and physiological effects of transcranial electrical stimulation position on motor evoked potentials in scoliosis surgery  

Microsoft Academic Search

BACKGROUND: During intraoperative monitoring for scoliosis surgery, we have previously elicited ipsilateral and contralateral motor evoked potentials (MEP) with cross scalp stimulation. Ipsilateral MEPs, which may have comprised summation of early ipsilaterally conducted components and transcallosally or deep white matter stimulated components, can show larger amplitudes than those derived purely from contralateral motor cortex stimulation. We tested this hypothesis using

YL Lo; YF Dan; YE Tan; A Teo; SB Tan; WM Yue; CM Guo; S Fook-Chong



Somatosensory evoked potentials elicited by stimulation of lower-limb nerves in amyotrophic lateral sclerosis  

Microsoft Academic Search

To determine lower limb somatosensory modifications in amyotrophic lateral sclerosis (ALS), we studied somatosensory evoked potentials (SEPs) elicited by stimulation of tibial posterior nerves (TP), sural nerves (SN), saphenous internous nerves (SA), and medial plantar nerves (PL) of both limbs in 24 ALS patients, and compared the results with those from 17 normal subjects. Responses were recorded according to the

Michel Georgesco; Antoine Salerno; William Camu



Plasticity associated changes in cortical somatosensory evoked potentials following spinal cord injury in rats  

Microsoft Academic Search

Spinal cord injury (SCI) causes a number of physiological and neurological changes resulting in loss of sensorimotor function. Recent work has shown that the central nervous system is capable of plastic behaviors post-injury, including axonal regrowth and cortical remapping. Functional integrity of afferent sensory pathways can be quantified using cortical somatosensory evoked potentials (SSEPs) recorded upon peripheral limb stimulation. We

Faith A. Bazley; Angelo H. All; Nitish V. Thakor; Anil Maybhate



Effects of hypodynamia–hypokinesia on somatosensory evoked potentials in the rat  

Microsoft Academic Search

The aim of this study was to determine if a prolonged period (7 or 14 days) of hypodynamia–hypokinesia (HH) affects the conduction of afferent input and the cortical and spinal responsiveness. Acute recordings of cortical and spinal somatosensory evoked potentials (SEPs) were performed after stimulation of the sciatic nerve in control rats and in rats submitted to 7 or 14

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



Motor-Evoked Potential Facilitation During Progressive Cortical Suppression by Propofol  

Microsoft Academic Search

We characterized the effects of various stimulation patterns on motor-evoked potentials (MEPs) elicited by repetitive transcranial magnetoelectric stimula- tion at different levels of cortical suppression by propofol. In 20 patients undergoing lumbar disk sur- gery, propofol target plasma concentrations (PTPCs) were increased incrementally by target plasma-level controlled infusion during the induction of anesthe- sia. MEPs were recorded from the muscles

Kai-Michael Scheufler; Josef Zentner



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

ERIC Educational Resources Information Center

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…

Bates, Tim; And Others




EPA Science Inventory

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


Stationary Pattern Adaptation and the Early Components in Human Visual Evoked Potentials.  

National Technical Information Service (NTIS)

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

H. K. Hudnell W. K. Boyes D. A. Otto



Neurophysiological Significance of the N1 and P1 Components of the Visual Evoked Potential,  

National Technical Information Service (NTIS)

One of the major disadvantages of the clinical use of the pattern visual evoked potential (VEP) in humans has been the failure to isolate and understand the significance of its major components. The two most important of these are N1 (a negative peak typi...

F. H. Previc



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


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. PMID:21095851

Ellingson, Roger M; Oken, Barry



Comparison of Single-Subject and Traditional Statistical Designs in Steady-State Evoked Potential Research.  

National Technical Information Service (NTIS)

An experiment was conducted to assess the relationship between level of auditory noise and a measure derived from the steady-state evoked potential (SSEP) called relative transmission time (RTT). The visual stimulus consisted of a 150-fL light that was mo...

D. R. Eddy S. L. Moise



Evaluating the Noise in Electrically Evoked Compound Action Potential Measurements in Cochlear Implants  

Microsoft Academic Search

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

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



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

ERIC Educational Resources Information Center

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…

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



Analysis of the Averaged Visually Evoked Potentials in Normal Children. (RIEEC Research Bulletin 3.)  

ERIC Educational Resources Information Center

Evaluated were the properties and fine structures of averaged visually evoked potentials (AVEP) in 60 normal children between the ages of 2 and 9 years. Electroencephalographic recordings were taken while white diffuse flashes were used to deliver visual stimuli to the Ss. Three types of AVEP patterns were discerned, with no relationship observed…

Mizutani, Tohru; And Others



EPA Science Inventory

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


Proprioceptive modulation of somatosensory evoked potentials during active or passive finger movements in man  

Microsoft Academic Search

The effects of active and passive finger movements on somatosensory potentials evoked by stimulation of the median nerve at the wrist or of finger I were investigated in 15 healthy volunteers. As compared to the resting condition, both active and passive movements of the stimulated hand fingers induced a marked reduction in the amplitude of the primary cerebral response (N20-P25

G Abbruzzese; S Ratto; E Favale; M Abbruzzese




EPA Science Inventory

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


Enhancement of Neuroplastic P2 and N1c Auditory Evoked Potentials in Musicians  

Microsoft Academic Search

P2 and N1c components of the auditory evoked potential (AEP) have been shown to be sensitive to remodeling of the auditory cortex by training at pitch discrimination in nonmusician subjects. Here, we investigated whether these neuroplastic components of the AEP are enhanced in musicians in accordance with their musical training histories. Highly skilled violinists and pianists and nonmusician controls listened

Antoine Shahin; Daniel J. Bosnyak; Laurel J. Trainor; Larry E. Roberts



Dermatomal somatosensory evoked potential demonstration of nerve root decompression after VAX-D therapy  

Microsoft Academic Search

Reductions in low back pain and referred leg pain associated with a diagnosis of herniated disc, degenerative disc disease or facet syndrome have previously been reported after treatment with a VAX-D table, which intermittently distracts the spine. The object of this study was to use dermatomal somatosensory evoked potentials (DSSEPs) to demonstrate lumbar root decompression following VAX-D therapy. Seven consecutive

William K. Naguszewski; Robert K. Naguszewski; Earl E. Gose



Detection of ophthalmic artery occlusion by visual evoked potential during carotid-ophthalmic artery aneurysm clipping.  


We report an intriguing case of carotid-ophthalmic artery (OA) aneurysm surgery, in which the visual evoked potential (VEP) wave diminished during temporary OA occlusion. VEP waves suddenly disappeared after clipping, and repositioning of the clip restored blood flow to the OA and recovered the VEP wave. PMID:21970779

Ota, Takahiro; Mizutani, Tohru; Horiba, Ayako



The use of anesthesia during evoked potential audiometry in goldfish (Carassius auratus)  

PubMed Central

Auditory evoked potentials (AEPs) have become a widely utilized measure of hearing sensitivity. Most investigators use pharmacological paralysis to reduce myogenic noise and immobilize the animal for stable electrical recordings, but additional anesthesia is generally not used because the most commonly available fish anesthetic, the cholinergic antagonist tricane methanosulfate (MS222), is known to disrupt hair cell and primary afferent physiology. Anesthetic agents that do not interfere with auditory function would be a useful adjunctant to paralytic immobilization and would reduce any possible distress incurred by prolonged immobilization. In this report we tested the opiate anesthetic Fentanyl and compared hearing thresholds in immobilized versus immobilized and anesthetized animals. Short-term effects of mild MS222 anesthesia were also measured via evoked potential audiometry. Animals were tested before and after Fentanyl injection (100, 500 and 2500 ?g g?1 fish body-weight) using standard evoked potential audiometry. Tone pips, 0.2 to 3 kHz, from an aerial loudspeaker served as stimuli. Fentanyl altered evoked potential waveforms slightly, but did not alter estimated threshold sensitivity. These results suggest Fentanyl be considered as a possible addition to AEP techniques in goldfish (Carassius auratus) and poikilothermic vertebrates generally.

Cordova, Micah S.; Braun, Christopher B.




EPA Science Inventory

Chlordimeform (CDM), a formamidine insecticide and monoamine oxidase (MAO) inhibitor, has recently been shown to produce profound changes in visual evoked potentials of hooded rats (Dyer and Boyes, The Toxicologist, 3: 13, 1983). Two experiments were performed to determine if the...


Hyperbaric oxygen in chronic progressive multiple sclerosis: visual evoked potentials and clinical effects  

Microsoft Academic Search

The effects of hyperbaric oxygen at a pressure of two atmospheres absolute were studied in a group of patients with chronic progressive multiple sclerosis. A slight but statistically insignificant shortening of the visual evoked potential latencies was seen after treatment with hyperbaric oxygen as compared with placebo treatment. The treatment did not appreciably halt the progression of the disease and

J Neiman; B Y Nilsson; P O Barr; D J Perrins



Measurement of Human Color Responses Using Visual Evoked Potential Elicited by Multi-Color Stimulation.  

National Technical Information Service (NTIS)

The simultaneous presentation of two color stimuli was used to determine whether a practical and rapid method of recording human color responses using visual evoked potentials (VEPs) can be done, Multi-color stimulation which consists of two iso-luminant ...

K. Momose J. Hanagata



Multiple Channel Detection of Steady-State Visual Evoked Potentials for Brain-Computer Interfaces  

Microsoft Academic Search

In this paper, novel methods for detecting steady-state visual evoked potentials using multiple electroencephalogram (EEG) signals are presented. The methods are tailored for brain-computer interfacing, where fast and accurate detection is of vital importance for achieving high information transfer rates. High detection accuracy using short time segments is obtained by finding combinations of electrode signals that cancel strong interference signals

Ola Friman; Ivan Volosyak; Axel Graser



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


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

Young, Yi-Ho



Prevention of spinal cord injury with time-frequency analysis of evoked potentials: an experimental study  

PubMed Central

OBJECTIVES—To verify the applicability and validity of time-frequency analysis (TFA) of evoked potential (EP) signals in detecting the integrity of spinal cord function and preventing spinal cord injury.?METHODS—The spinal cord was simulated during surgery in 20 mature rats by mechanically damaging the spinal cord. Cortical somatosensory evoked potential (CSEP), spinal somatosensory evoked potential (SSEP), cortical motor evoked potential (CMEP), and spinal cord evoked potential (SCEP) were used to monitor spinal cord function. Short time Fourier transform (STFT) was applied to the CSEP signal, and cone shaped distribution (CSD) was used as the TFA algorithm for SSEP, CMEP, and SCEP signals. The changes in the latency and amplitude of EP signals were measured in the time domain, and peak time, peak frequency, and peak power were measured in the time-frequency distribution (TFD).?RESULTS—The TFDs of EPs were found to concentrate in a certain location under normal conditions. When injury occurred, the energy decreased in peak power, and there was a greater dispersion of energy across the time-frequency range. Strong relations were found between latency and peak time, and amplitude and peak power. However, the change in peak power after injury was significantly larger than the corresponding change in amplitude (p<0.001 by ANOVA).?CONCLUSIONS—It was found that TFA of EPs provided an earlier and more sensitive indication of injury than time domain monitoring alone. It is suggested that TFA of EP signals should therefore be useful in preventing spinal cord injury during surgery.??

Hu, Y; Luk, K; Lu, W; Holmes, A; Leong, J



Multilevel somatosensory evoked potentials (SEPs) for spinal cord monitoring in descending thoracic and thoraco-abdominal aortic surgery  

Microsoft Academic Search

The usefulness of somatosensory evoked potential (SEP) monitoring as a means of preventing paraplegia in descending aorta surgery was evaluated in 47 consecutive cases operated on for isthmic (14 cases), thoracic (22 cases), or thoraco-abdominal (11 cases) repair. An aortic dissection was found in 11 cases (acute in 6). Somatosensory evoked potentials were obtained by unilateral left and right posterior





EPA Science Inventory

Because solvents may selectively alter portions of visual evoked potentials, we examined the effects of carbon disulfide (CS2) on flash (FEPs) and pattern reversal (PREPs) evoked potentials. Long-Evans rats were administered (ip) carbon disulfide (CS2) either acutely or for 30 da...


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

PubMed Central

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

Poplawsky, Alexander J.; Dingledine, Raymond



Preservation of motor evoked potentials under anesthesia in children with spinal muscular atrophy type II undergoing spinal deformity surgery.  


Spinal muscular atrophy is a progressive condition in which movement is gradually lost as a result of the loss of spinal motor neurons. Individuals with this condition may require surgical correction of a secondary scoliosis. Motor evoked potentials were recorded using transcranial electrical stimulation in four such individuals undergoing surgery. All the patients were nonambulatory and in wheelchairs. Motor evoked potentials were recordable in both upper and lower limb muscles, with similar stimulation parameters to control subjects undergoing surgery for idiopathic scoliosis. The amplitudes of the motor evoked potentials were similar to those in control subjects, although the latencies were shorter reflective of the smaller stature of the spinal muscular atrophy patients. The relative preservation of the motor evoked potentials despite the patients' poor voluntary motor control suggests that there is a selective preservation of the motor neurons mediating the motor evoked potential in spinal muscular atrophy and a maintenance of the conduction velocities of the corticospinal tract. PMID:23912577

Norton, Jonathan A; Roy, François D; Mahood, James K



Research on the effectiveness of intermittent cervical traction therapy, using short-latency somatosensory evoked potentials  

Microsoft Academic Search

.   Short-latency somatosensory evoked potentials (SSEPs) were measured before and after intermittent cervical traction therapy\\u000a to serve as objective indicators of therapy effectiveness. The subjects were 29 patients with myelopathy, 23 with cervical\\u000a radiculopathy, 28 with cervical sprain, and 26 healthy individuals. SSEPs were recorded by stimulating the median nerve, and\\u000a the negative potentials elicited from the brachial plexus (N9),

Mikihiko Hattori; Yasumasa Shirai; Takafumi Aoki



Shifts of visual spatial attention modulate a steady-state visual evoked potential  

Microsoft Academic Search

Although the effects of static allocations of visual spatial attention have been investigated using event-related potentials, most studies of shifts in visual spatial attention have been limited to behavioural measures. This study applied electroencephalographic measures to shifts in visual spatial attention in an effort to elucidate the time courses of such shifts. Using a custom-developed steady-state evoked potential analysis system,

Matthew Belmonte



Single sweep analysis of visual evoked potentials through a model of parametric identification  

Microsoft Academic Search

An original method is presented for the single sweep analysis of visual evoked potentials (VEP's). The introduced algorithm bases upon an AutoRegressive with eXogenous input (ARX) modelling. A Least Squares procedure estimates the coefficients of the model and allows to obtain a complete black-box description of the signal generation mechanism, besides providing a filtered version of the single sweep potential.

S. Cerutti; G. Baselli; D. Liberati; G. Pavesi



Stimulus novelty, task relevance and the visual evoked potential in man  

NASA Technical Reports Server (NTRS)

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.

Courchesne, E.; Hillyard, S. A.; Galambos, R.



[Effect of suloctidil on the reduced evoked potentials in brain slices in low glucose perfusate].  


Effects of suloctidil [erythro-1-(4-isopropylthiophenyl)-2-n-octylaminopropanol] on reduced evoked potentials in low glucose perfusate were studied using guinea-pig prepyriform cortex in vitro. The amplitude of evoked potential to paired electrical stimulation of the olfactory tract in cerebral slices was consistently and reversibly suppressed by the perfusion with low glucose (3 mM)-Krebs-Ringer's solution. The amplitude reduction after 10 min exposure to the perfusate was fairly reproducible in the same preparation. The amplitude reduction was always accompanied with significant facilitation of "postactivation potentiation", estimated from the size of the first and second response to paired stimulation. Perfusion of brain slices with low glucose Krebs-Ringer's solution containing 10(-7)-10(-6) g/ml suloctidil for 10 min, however, effectively prevented the reduction of amplitude of evoked potentials to below 30-50% of the control value. The facilitation of postactivation potentiation under the low glucose condition was also suppressed by the drug. Dihydroergotoxin, 3 X 10(-6) g/ml, also showed a comparable effect as 10(-6) g/ml suloctidil. These data suggest that suloctidil possesses a brain energy economizing effect such as activation of oxygen, glucose uptake or production of high energy substance. PMID:6323287

Nishi, H; Hori, N; Katsuda, N



Steady-state evoked potentials possibilities for mental-state estimation  

NASA Technical Reports Server (NTRS)

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.

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



[Ipsilateral masking of auditory evoked potentials: a method of studying multiple sclerosis].  


20 normal subjects and 39 patients with multiple sclerosis were the control and the test groups. Auditory brainstem potentials to 60 dB nHL, 11/s clicks, were recorded under ipsilateral broad-band noise masking at S/N ratio of + 60 dB (unmasked condition), + 20 dB, + 10 dB and 0 dB. In the control group the ABP were absent only in 1 subject at S/N = 0 dB. In the group of 16/39 patients with definite multiple sclerosis, 11 had no ABP at S/N = 0 dB, 6 at S/N = + 10 dB and 5 at S/N = + 20 dB. The ABP waveform per se, in the same subjects, was abnormal in 7 and doubtful in 5. These results are discussed in terms of sensitivity, specificity and efficiency of the test to be applied. The best predictive value is achieved by combining a strict morphological criterion with the results of the ipsilateral masking. Moreover, the ipsilateral masking test positive findings are equally distributed in the group of patients with and without signs of neurological involvement of the brainstem. PMID:6534258

Antonelli, A; Collette, J L; Bellotto, R; Felisati, G; Pavani, M; Cesaro, P; Degos, J D; Peynegre, R



Fast Detection of Unexpected Sound Intensity Decrements as Revealed by Human Evoked Potentials  

PubMed Central

The detection of deviant sounds is a crucial function of the auditory system and is reflected by the automatically elicited mismatch negativity (MMN), an auditory evoked potential at 100 to 250 ms from stimulus onset. It has recently been shown that rarely occurring frequency and location deviants in an oddball paradigm trigger a more negative response than standard sounds at very early latencies in the middle latency response of the human auditory evoked potential. This fast and early ability of the auditory system is corroborated by the finding of neurons in the animal auditory cortex and subcortical structures, which restore their adapted responsiveness to standard sounds, when a rare change in a sound feature occurs. In this study, we investigated whether the detection of intensity deviants is also reflected at shorter latencies than those of the MMN. Auditory evoked potentials in response to click sounds were analyzed regarding the auditory brain stem response, the middle latency response (MLR) and the MMN. Rare stimuli with a lower intensity level than standard stimuli elicited (in addition to an MMN) a more negative potential in the MLR at the transition from the Na to the Pa component at circa 24 ms from stimulus onset. This finding, together with the studies about frequency and location changes, suggests that the early automatic detection of deviant sounds in an oddball paradigm is a general property of the auditory system.

Althen, Heike; Grimm, Sabine; Escera, Carles



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

Microsoft Academic Search

The aim of the study was to directly compare the threshold electrical charge density of the retina (retinal threshold) in rabbits for the generation of electrical evoked potentials (EEP) by delivering electrical stimulation with a custom-made microelectrode array (MEA) implanted into either the subretinal or suprachoroidal space. Nine eyes of seven Dutch-belted rabbits were studied. The electroretinogram (ERG), visual evoked

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



Visual evoked potentials in early diagnosis of demyelinating diseases - a case report of Devic's disease  

PubMed Central

Summary Background Devic’s disease, also known as neuromyelinitis optica (NMO), is a severe, rare demyelinating disorder, previously considered to be a form of multiple sclerosis (MS). The aim of this study was to present the case report of 21-year-old woman with a very early diagnosis of Devic’s disease, established following electrophysiological testing. Case Report A 21-year-old woman was referred to Warsaw Medical University, Department of Ophthalmology, with subjective visual impairment. The patient underwent a full clinical examination, colour vision and Goldmann visual field testing, fluorescein angiography, OCT, multifocal ERG, and visual evoked potentials (VEPs). Conclusions Visual evoked potentials are a very useful diagnostic tool in optic nerve neuropathies. In our patient, the electrophysiological testing allowed us to establish a proper diagnosis very early, before typical clinical signs of Devic’s disease.

Langwinska-Wosko, Ewa; Szulborski, Kamil; Broniek-Kowalik, Karina



Visual and somatosensory evoked potentials in vitamin E deficiency with cystic fibrosis.  


Patients with cystic fibrosis (CF) and pancreatic malabsorption frequently have vitamin E deficiency. Affected patients may develop spinocerebellar degeneration with dysarthria, ataxia, proximal weakness, proprioceptive loss and areflexia. Of a highly selected group of 10 patients with vitamin E levels below 5 micrograms/ml (normal 5-20 micrograms/ml), 7 had abnormal neurological examinations, predominantly affecting vibration and joint position perception with some severely affected patients manifesting diminished visual acuity, tremor, ataxia and diffuse weakness. Evoked potential studies showed marked abnormalities in 3 patients, demonstrating deficits in the optic pathways and in the cervical cord dorsal column pathways. Evoked potential studies may supplement careful neurological examination in patients with CF before and after supplementation with vitamin E to evaluate their progression and response to treatment. PMID:2454791

Kaplan, P W; Rawal, K; Erwin, C W; D'Souza, B J; Spock, A



Topography of middle-latency somatosensory evoked potentials following painful laser stimuli and non-painful electrical stimuli.  


The aim of this study was to compare cerebral evoked potentials following selective activation of A beta and A delta fibers. In 15 healthy subjects, A beta fibers were activated by electrical stimulation of the left radial nerve at the wrist. A delta fibers were activated by short painful radiant heat pulses, applied to the dorsum of the left hand by a CO2 laser. Evoked potentials were recorded with 15-27 scalp electrodes, evenly distributed over both hemispheres (bandpass 0.5-200 Hz). The laser-evoked potentials exhibited a component with a mean peak latency of 176 msec (N170). Its scalp topography showed a parieto-temporal maximum contralateral to the stimulus side. In contrast, the subsequent vertex negativity (N240), which appeared about 60 msec later, had a symmetrical scalp distribution. Electrically evoked potentials showed a component at 110 msec (N110), that had a topography similar to the laser-evoked N170. The topographies of the N170 and N110 suggest that they may both be generated in the secondary somatosensory cortex. There was no component in the electrically evoked potential that had a comparable interpeak latency to the following vertex potential: for N60 it was longer, for N110 it was shorter. On the other hand, in the laser-evoked potentials no component could be identified the topography of which corresponded to the primary cortical component N20 following electrical stimulation. PMID:7688283

Kunde, V; Treede, R D




EPA Science Inventory

Pattern reversal evoked potentials (PREPs), flash evoked potentials (FEPs), optic nerve axonal transport, and body temperature were measured in hooded rats treated with either saline or the formamidine insecticide/acaricide, chlordimeform (CDM). Rats receiving CDM had low body te...


Can Vestibular-Evoked Myogenic Potentials Help Differentiate M?ni?re Disease from Vestibular Migraine?  

PubMed Central

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

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



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


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. Hum Brain Mapp 35:4267-4281, 2014. © 2014 Wiley Periodicals, Inc. PMID:24706574

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



The use of visual and chemosensory evoked potentials in environmental and occupational health.  


The application of visual (VEP) and chemosensory evoked potentials (CSEP) in occupational and environmental health is briefly reviewed. VEPs have been used extensively in experimental neurotoxicity and play an increasingly important role in human neurotoxicity testing. The similarity of VEP waveforms in different species renders them useful for cross-species extrapolation. CSEPs, used in conjunction with traditional psychophysical tests and rating scales, offer a promising new approach to the study of indoor air pollution. PMID:8325262

Otto, D A; Hudnell, H K



Spectro-temporal representations and time-varying spectra of evoked potentials  

Microsoft Academic Search

Evoked potential waveforms are generally of a dynamic, transient character. Consequently, their spectral energy distribution cannot be adequately described by time-invariant representations, such as the power density spectrum. Obviously, aspectro-temporal description is needed. Appropriate means for obtaining such descriptions are discussed, on the basis of theoretical considerations concerning simultaneous time-frequency representations and methods ofshort-time spectral analysis. With reference to the

J. P. C. de Weerd; J. I. Kap



Differential effects on the laser evoked potential of selectively attending to pain localisation versus pain unpleasantness  

Microsoft Academic Search

Objective: To determine the effects on the laser evoked potential (LEP) of selectively attending to affective (unpleasantness) versus sensory-discriminative (localisation) components of pain.Methods: LEPs, elicited by painful CO2 laser stimulation of two areas of the right forearm, were recorded from 62 electrodes in 21 healthy volunteers, during three tasks that were matched for generalised attention: Localisation (report stimulus location), Unpleasantness

D. E Bentley; A Watson; R.-D Treede; G Barrett; P. D Youell; B Kulkarni; A. K. P Jones



Auditory evoked potentials: Developmental changes of threshold and amplitude following early acoustic trauma  

Microsoft Academic Search

Acoustically traumatized (primed) or sham primed 110 inbred C57BL\\/6J mice at 16 days of age. Auditory evoked potentials (AEPs) were subsequently determined for the inferior colliculus or medial geniculate body. Priming immediately elevated the AEP threshold by 43 db, but this shift declined to a 14-db increase within 2 days. The peak-to-peak AEP amplitude was also reduced but became larger

James F. Willott; Kenneth R. Henry



Dichoptic Stimulation Improves Detection of Glaucoma with Multifocal Visual Evoked Potentials  

Microsoft Academic Search

PURPOSE. To determine whether simultaneous binocular (di- choptic) stimulation for multifocal visual evoked potentials (mfVEP) detects glaucomatous defects and decreases intereye variability. METHODS. Twenty-eight patients with glaucoma and 30 healthy subjects underwent mfVEP on monocular and dichoptic stim- ulation. Dichoptic stimulation was presented with the use of virtual reality goggles (recording time, 7 minutes). Monocular mfVEPs were recorded sequentially for

Hemamalini Arvind; Alexander Klistorner; Stuart Graham; John Grigg; Ivan Goldberg; Asya Klistorner; Frank A. Billson



Interhemisphere Asymmetry of Auditory Evoked Potentials in Humans and Mismatch Negativity during Sound Source Localization  

Microsoft Academic Search

Results of studies in humans of long-latency auditory evoked potentials and mismatch negativity in conditions of dichotic\\u000a stimulation during presentation of deviant stimuli producing instantaneous changes in stimulus azimuth from the null to +22.5°\\u000a or movement at rates of 11.25–112.5°\\/sec from the midline of the head across the left and right hemispheres towards each ear\\u000a are presented. These studies showed

S. F. Vaitulevich; L. B. Shestopalova



Effects of Tobacco and Distraction on Sensory and Slow Cortical Evoked Potentials during Task Performance  

Microsoft Academic Search

Sensory and slow cortical evoked potentials (EP) of female smokers were investigated under two conditions in separate sham and real smoking sessions: (1) a non-distraction (ND) condition consisting of a constant foreperiod S1-S2, i.e., a single-choice reaction time situation with a tone (S1)\\/light (S2) key press sequence, and (2) a task distraction (TD) condition identical to ND with the addition

Verner J. Knott



Effects of octreotide on esophageal visceral perception and cerebral evoked potentials induced by balloon distension  

Microsoft Academic Search

Objective: Octreotide, a somatostatin analog, is antinociceptive and increases perception threshold in the rectum. The aim of this study was to determine whether octreotide alters esophageal sensory thresholds and cortical evoked potentials (CEPs) resulting from intraesophageal balloon distension. Methods: Twelve healthy volunteers (six men and six women, median age 25 yr, range 21–60 yr) underwent a randomized, double-blind, placebo-controlled trial

Brian T. Johnston; Jay Shils; Louis P. Leite; Donald O. Castell



Long-lasting depression of motor-evoked potentials to transcranial magnetic stimulation following exercise  

Microsoft Academic Search

We used transcranial magnetic stimulation to study the modulation of motor cortex excitability after rapid repetitive movements. Eleven healthy subjects aged 24–32 years were evaluated. Serial motor-evoked potential (MEP) recordings were performed from the right thenar eminence every 5 min for a period of 20 min at rest and for a period of 35 min after repetitive abduction-adduction of the

Giampietro Zanette; Claudio Bonato; Alberto Polo; Michele Tinazzi; Paolo Manganotti; Antonio Fiaschi



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

Microsoft Academic Search

Study design:Cross-sectional study.Objectives:To observe if there is a relationship between the level of injury by the American Spinal Cord Injury Association (ASIA) and cortical somatosensory evoked potential (SSEP) recordings of the median nerve in patients with quadriplegia.Setting:Rehabilitation Outpatient Clinic at the university hospital in Brazil.Methods:Fourteen individuals with quadriplegia and 8 healthy individuals were evaluated. Electrophysiological assessment of the median nerve

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



Deliberate hypotension for spinal fusion: Prospective randomized study with evoked potential monitoring  

Microsoft Academic Search

Twenty-four patients requiring spinal fusion with Harrington rod instrumentation were studied prospectively to determine the\\u000a effects of moderate hypotension on blood loss, operating conditions, operating time and spinal cord function. Hypotension\\u000a reduced blood loss and improved operating conditions but did not shorten operating time. Five patients had alterations in\\u000a somatosensory cortical evoked potentials after straightening of the spine that prompted

Betty L. Grundy; Clyde L. Nash; Richard H. Brown



Somatosensory and Motor Evoked Potentials in Patients with Tumours in the Spinal Canal  

Microsoft Academic Search

Summary  ?Motor and sensory evoked potentials were recorded in 27 patients with expanding spinal tumour. The patients were divided\\u000a into 2 groups: I. tumours at the level of the spinal cord [18] and II. at the level of the cauda equina [9]. On the basis\\u000a of the localization of the tumour, midline and lateral subgroups were distinguished.\\u000a \\u000a ?The latencies of motor

G. Székely Jr.; G. I. Csécsei; L. Mikó



Usefulness and Pitfalls of Intraoperative Spinal Motor Evoked Potential Recording by Direct Cortical Electrical Stimulation  

Microsoft Academic Search

Summary  ¶?Objective. The aim of this study is to investigate the usefulness and problems with spinal motor evoked potential (MEP) recording, especially\\u000a the reasons for failed recording. We report our personal experience over the last 8 years in patients with lesions adjacent\\u000a to the primary motor cortex.\\u000a \\u000a \\u000a Methods. MEP records of 50 consecutive patients were retrospectively reviewed. MEP was recorded by

T. Horikoshi; T. Omata; M. Uchida; Y. Asari; H. Nukui



Brain controlled robotic platform using steady state visual evoked potentials acquired by EEG  

Microsoft Academic Search

This paper describes a capstone design project by four undergraduate students (first four authors listed in alphabetical order by last name). A noninvasive brain computer interface (BCI) based on the steady state visual evoked potential (SSVEP) has been developed and utilized in controlling an iRobot platform remotely in real-time closed-loop fashion using video feedback from the robot's eye view to

S. Dasgupta; M. Fanton; J. Pham; M. Willard; H. Nezamfar; B. Shafai; D. Erdogmus



Abnormal subcortical somatosensory evoked potentials indicate high cervical myelopathy in achondroplasia  

Microsoft Academic Search

Children with achondroplasia may have high cervical myelopathy due to stenosis of the cranio-cervical junction resulting\\u000a in neurological disability and an increased rate of sudden death. To detect myelopathy we recorded somatosensory evoked potentials\\u000a (SEPs) after median nerve stimulation in 30 patients with achondroplasia aged 13 months to 18 years (mean 6 years). In addition\\u000a to the conventional technique of

R. Boor; G. Fricke; K. Brühl; J. Spranger



Effects of Lactate-Induced Panic Attacks on Brain Stem Auditory Evoked Potentials  

Microsoft Academic Search

As the clinical symptomatology of panic attacks may be conceivably related to abnormal brain stem activity, the present study examined the effect of lactate-precipitated panic on brain stem auditory evoked potentials (BSAEPs). The subjects were 27 patients who met DSM-III criteria for panic disorder (Pd), agoraphobia with panic attacks (AgPa) or agoraphobia (Ag). Following drug washout, patients were tested in

Verner J Knott; Yvon D. Lapierre



Motor evoked potentials in multiple sclerosis patients without walking limitation: amplitude vs. conduction time abnormalities  

Microsoft Academic Search

We used Motor Evoked Potentials (MEPs), elicited by transcranial magnetic stimulation, for assessing a motor pathways dysfunction\\u000a in a selected group of Multiple Sclerosis (MS) patients, without limitation in walking. We selected 32 Relapsing Remitting\\u000a MS patients, in remission phase, with EDSS ? 3.5 and 20 healthy individuals with similar height and age distribution. We measured\\u000a the following MEP parameters: motor thresholds;

Andrea Gagliardo; Francesca Galli; Antonello Grippo; Aldo Amantini; Cristiana Martinelli; Maria Pia Amato; Walter Borsini



Monitoring Glaucoma Progression with Visual Evoked Potentials of the Blue-Sensitive Pathway  

Microsoft Academic Search

PURPOSE. To determine the value of visual evoked potentials with blue-on-yellow pattern stimulation in follow-up of glau- coma. METHODS. This prospective longitudinal concurrent study in- cluded a heterogeneous cohort of two groups, perimetric (n 161) and preperimetric (n 118), of patients with chronic open-angle glaucoma and 113 healthy control subjects. In the preperimetric glaucoma group, patients showed glaucomatous abnormalities of

Folkert K. Horn; Jost B. Jonas; Wido M. Budde; Anselm M. Junemann; Christian Y. Mardin; Matthias Korth


Comparison of the latencies between bone and air conduction in the auditory brain stem evoked potential.  


Brain stem auditory evoked potentials obtained by air and bone conduction were investigated in 22 subjects. The necessity for a carefully selected stimulus being presented to the headphone and the bone vibrator is discussed. Latency values of both responses are presented for wave V. Bone conduction showed latencies which were longer than those obtained by air conduction (about 0.9 msec). Possible mechanisms for this delay are discussed. PMID:6191955

Boezeman, E H; Kapteyn, T S; Visser, S L; Snel, A M



Visual evoked potential correlates of positive/negative symptoms in schizophrenia.  


Previous studies of schizophrenic patients have found evoked potential (EP) correlates of clinical symptomatology, including EP differences between subtypes of schizophrenia. In the current study, 14 medicated male schizophrenics underwent flash visual evoked potentials (VEP) and were clinically rated for positive and negative symptoms. We tested the hypothesis that positive symptoms would be associated with VEP latency reduction and negative symptoms with latency prolongation. Patients were divided into predominantly positive symptom and predominantly negative symptom groups using a combination of positive and negative symptom ratings. Patients with predominantly positive symptoms exhibited reduced latencies when compared with predominantly negative symptom patients. Similarly, significant negative correlations between positive symptom ratings and P200 latency variables were found. Correlations between negative symptom measures and P200 latencies (in the opposite direction) were also noted, but were less significant. These relationships persisted when confounders were statistically controlled for. The results are consistent with previous findings of evoked potential correlates of clinical symptomatology, especially those finding EP latency correlates of psychosis severity and affective blunting. The findings are discussed in relationship to concepts relevant to psychosis, including arousal, sensory gating, and the dopamine hypothesis. PMID:2310795

Schwarzkopf, S B; Lamberti, J S; Jiminez, M; Kane, C F; Henricks, M; Nasrallah, H A



[Role of multimodal evoked potentials in evaluations of persistent vegetative state of nontraumatic origin].  


Persistent vegetative state (PVS) is a kind of release from coma, manifesting by absence of any signs of cognitive activity. Progress in reanimatology leads to an increase in the number of patients with PVS, thus creating a new medical and social problem. Study of atraumatic PVS acquires special importance because of a drastic increase in its incidence, necessitating definition of criteria of this state formation and its prognostic signs. Multimodal evoked potentials (MEP) now play an important role in diagnosis and prediction of PVS. The impact of acoustic stem (ASEP), visual (VEP), somatosensory (SSEP), and cognitive (CEP) evoked potentials is analyzed and early diagnostic and prognostic neurophysiological criteria are defined. Results of dynamic examinations of 23 patients (9 men and 14 women) aged 10-67 years with atraumatic PVS are presented. According to neurophysiological data, PVS in the majority of patients is characterized by absence of cognitive responses to a significant stimulus (wave P300) during examinations of CEP and of cortical response during examination of SSEP. VEP and long latent acoustic evoked potentials are as rule intact in atraumatic PVS. According to ASEP, stem functions were intact or slightly changed in the examined patients with PVS. Prognostically unfavorable and relatively favorable signs in the time course of MEP are defined. PMID:12611156

Plekhanova, S A; Gnezditski?, V V; Piradov, M A; Popova, L M



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

PubMed Central

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.

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



Temperature effects on evoked potentials of hippocampal slices from euthermic chipmunks, hamsters and rats  

NASA Technical Reports Server (NTRS)

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.

Hooper, D. C.; Martin, S. M.; Horowitz, J. M.



Age-related decline in thermal adaptation capacities: an evoked potentials study.  


Aging is associated with changes in thermosensitivity and decreases in the functionality of the autonomic thermoregulation. The underlying mechanisms are, however, not fully understood. Elderly subjects may undergo functional changes in the integration process of the thermal sensory system, especially in their thermal adaptation capacities. To verify this hypothesis, we compared thermal evoked responses in younger and older subjects exposed to thermoneutral (27 °C) and warm (30 °C) environments. In the warm environment, the amplitudes of thermal evoked potentials (EPs) were significantly lower in older than in younger subjects, whereas in the thermoneutral environment, the EP amplitudes were similar in both groups. These findings suggest that thermal adaptation capacities are reduced in elderly individuals, due to a dysfunction of C-fibers with aging, particularly expressed by lowered adaptation capacities to temperature variations. PMID:24611695

Kemp, Jennifer; Després, Olivier; Pebayle, Thierry; Dufour, André



Noise-induced tinnitus: auditory evoked potential in symptomatic and asymptomatic patients  

PubMed Central

OBJECTIVES: We evaluated the central auditory pathways in workers with noise-induced tinnitus with normal hearing thresholds, compared the auditory brainstem response results in groups with and without tinnitus and correlated the tinnitus location to the auditory brainstem response findings in individuals with a history of occupational noise exposure. METHOD: Sixty individuals participated in the study and the following procedures were performed: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25–8 kHz and auditory brainstem response. RESULTS: The mean auditory brainstem response latencies were lower in the Control group than in the Tinnitus group, but no significant differences between the groups were observed. Qualitative analysis showed more alterations in the lower brainstem in the Tinnitus group. The strongest relationship between tinnitus location and auditory brainstem response alterations was detected in individuals with bilateral tinnitus and bilateral auditory brainstem response alterations compared with patients with unilateral alterations. CONCLUSION: Our findings suggest the occurrence of a possible dysfunction in the central auditory nervous system (brainstem) in individuals with noise-induced tinnitus and a normal hearing threshold.

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



Brainstem tuberculosis.  


We present a case of a 38-year-old-man who presented with 1-week history of developing weakness of peripheral and cranial nerves. His MRI scan of the brain showed a large cavitating lesion at the brainstem and two further lesions of the right cerebral cortex and his CT chest showed features of old tuberculosis (TB). The identification of acid-fast bacilli was confirmed by analysis of bronchoalveolar lavage taken during bronchoscopy. He was started on anti-TB medications and repeat MRI 3 months later confirmed shrinkage of the cavitating lesion. PMID:23868024

Demetriou, George A



Epicranial sensory evoked potential recordings for repeated assessment of cortical functions in mice.  


In the present study, we describe a simple and minimally invasive method to record sensory evoked potentials (SEP) in the anesthetized mouse. The hardware includes a 16-channel acquisition system with a high signal/noise ratio and high temporal resolution. Under general anesthesia the skull is exposed and stainless steel electrodes are placed directly over the bone. A computer controlled electromechanical stimulation is applied to a single whisker or a group of whiskers unilaterally and cortical responses are recorded bilaterally. Primary SEP are detected over the contralateral barrel cortex, but delayed signals appear over the motor cortex, secondary somatosensory cortex and the ipsilateral hemisphere. The size of evoked SEP correlates with the number of stimulated whiskers and responses are reproducible and consistent over time when recorded repeatedly for up to 6 weeks. We conclude that epicranial multichannel recording of SEP represents an interesting, minimally invasive approach to monitor repeatedly cortical activity and study certain aspects of long-term plasticity of evoked responses in mice. PMID:10771075

Troncoso, E; Muller, D; Czellar, S; Zoltan Kiss, J



Motor and somatosensory evoked potentials in Autosomal Dominant Hereditary Spastic Paraparesis (ADHSP) linked to chromosome 2p, SPG4  

Microsoft Academic Search

The aim of our study was to evaluate Motor Evoked Potentials (MEPs) and cortical excitability, using Transcranial Magnetic Stimulation (TMS) as well as short latency Somatosensory Evoked Potentials (SEPs) in Autosomal Dominant Hereditary Spastic Paraparesis (ADHSP) patients.MEPs were recorded from upper and lower limb muscles in 12 patients (7m and 5f) affected by ADHSP with spastin mutation (SPG4). We measured:

F. Sartucci; S. Tovani; L. Murri; L. Sagliocco



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

Microsoft Academic Search

The present study evaluates motor functional recovery after C2 spinal cord hemisection with or without contralateral brachial root transection, which causes a condition that is similar to the crossed phrenic phenomenon on rats. Descending motor pathways, including the reticulospinal extrapyramidal tract and corticospinal pyramidal tracts, were evaluated by transcranial magnetic motor-evoked potentials (mMEPs) and direct cortical electrical motor-evoked potentials (eMEP),

Minoru Fujiki; Hidenori Kobayashi; Ryo Inoue; Keisuke Ishii



Concomitant hypertension, bradycardia, and loss of transcranial electric motor evoked potentials during pedicle hook removal: report of a case.  


Neurophysiologic monitors in the form of transcranial electric motor evoked potentials (tceMEPs) and somatosensory evoked potentials (SSEPs) have become widely used modalities to monitor spinal cord function during major orthopedic spine procedures. In combination with invasive and non-invasive clinical monitoring and an anesthesia information management system (AIMS), we promptly recognized an acute change in hemodynamic and neurophysiologic parameters, managed intraoperative spinal cord contusion, and successfully minimized iatrogenic injury to the spinal cord during corrective spine surgery. PMID:21210192

Ambardekar, A P; Sestokas, A K; Schwartz, D M; Flynn, J M; Rehman, M



Direct comparison of two statistical methods for determination of evoked-potential thresholds  

NASA Astrophysics Data System (ADS)

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.

Langford, Ted L.; Patterson, James H., Jr.



Neuronal current magnetic resonance imaging of evoked potentials and neural oscillations  

NASA Astrophysics Data System (ADS)

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

Jiang, Xia


Topographic mapping of cortical potentials evoked by distension of the human proximal and distal oesophagus.  


We describe cortical potentials evoked by balloon distension of the proximal and distal oesophagus in 8 healthy right handed volunteers. Oesophageal stimulation was performed using a pump which rapidly inflated a 2 cm silicone balloon positioned either 3 cm distal to the upper oesophageal sphincter or 5 cm proximal to the lower oesophageal sphincter, at a frequency of 0.2 Hz, using inflation volumes which produced a definite but not painful sensation. Oesophageal evoked cortical potentials were recorded in all subjects with an initial negative and positive component (N1 and P1), followed by a second negative and positive component (N2 and P2) in 6 subjects. The morphology and the scalp topography of the N1 component elicited by proximal and distal oesophageal stimulation suggests activation of the primary somatosensory cortex and/or the insular. There was also evidence for hemispheric dominance for the N1 potential which was independent of handedness. The frontal emphasis of the proximal oesophageal N1 component, in contrast to the central emphasis of the distal oesophageal N1 component, suggests that different neuronal populations were activated by stimulation of the two sites. The frontal emphasis of the ensuing P1 component from both oesophageal sites suggests that it originates in a separate precentral source. The topography of the N2 components obtained by stimulation of either oesophageal site was similar to that of the N1 component, suggesting that they originate in similar areas of the cortex. The P2 component evoked by stimulation of both oesophageal sites was localised at the vertex. The inter- and intra-subject variation in the morphology of the N2 and P2 components suggests that secondary cortical processes related to cognition may be involved in their generation. PMID:7750447

Aziz, Q; Furlong, P L; Barlow, J; Hobson, A; Alani, S; Bancewicz, J; Ribbands, M; Harding, G F; Thompson, D G



Pattern reversal visual evoked potentials after alcohol administration among men at risk for alcoholism.  


The P100 component of the pattern reversal visual evoked potential was used to compare men at high risk for alcoholism and control subjects before and after a low (0.5 g/kg) dose of ethanol. The high risk and control subjects did not differ in age, self-reported ethanol consumption, or estimates of ethanol metabolism rates, but changes in the occipital P100 latency differentiated them following ethanol administration. The P100 latency changes that distinguished high risk from control subjects were lateralized and provide preliminary evidence that perceptual visual stimulus processing is differentially affected in the two groups following ethanol administration. PMID:3237913

Pollock, V E; Volavka, J; Goodwin, D W; Gabrielli, W F; Mednick, S A; Knop, J; Schulsinger, F



Underwater Anesthesia of Diamondback Terrapins (Malaclemys terrapin) for Measurement of Auditory Evoked Potentials  

PubMed Central

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.

Christiansen, Emily F; Piniak, Wendy E D; Lester, Lori A; Harms, Craig A



Effect of alpha-lipoic acid on visual evoked potentials in rats exposed to sulfite  

Microsoft Academic Search

This study aimed to investigate the effect of alpha-lipoic acid (LA) administration on sulfite-induced alterations in visual evoked potentials (VEPs). Fifty two male albino Wistar rats were randomized into four experimental groups as follows; control (C), LA treated (L), sodium metabisulfite (Na2S2O5) treated (S), Na2S2O5+LA treated (SL). Na2S2O5 (260 mg\\/kg\\/day) and LA (100 mg\\/kg\\/day) were given by intragastric intubation for 5 weeks. The

Narin Derin; Deniz Akpinar; Piraye Yargicoglu; Aysel Agar; Mutay Aslan



Evoked Potential Monitoring Identifies Possible Neurological Injury During Positioning for Craniotomy  

PubMed Central

Somatosensory evoked potential (SSEP) monitoring is commonly used to detect changes in nerve conduction and prevent impending nerve injury. We present a case series of 2 patients who had SSEP monitoring for their surgical craniotomy procedure, and who, upon positioning supine with their head tilted 30–45 degrees, developed unilateral upper extremity SSEP changes. These SSEP changes were reversed when the patients were repositioned. These cases indicate the clinical usefulness of monitoring SSEPs while positioning the patient and adjusting position accordingly to prevent injury.

Anastasian, Zirka H.; Ramnath, Brian; Komotar, Ricardo J.; Bruce, Jeffrey N.; Sisti, Michael B.; Gallo, Edward J.; Emerson, Ronald G.; Heyer, Eric J.



A PC data-base with analytical applications for evoked potentials.  


Visual Evoked Potentials (VEPs) are gaining ground in the research for diagnosis of neurological disorders and visual defects, as a non-invasive diagnostic tool. Yet, the methods used towards these goals are not universal and far from able to provide a common ground among researchers in collecting, analyzing and comparing their results. This paper is an attempt to close the gap. We have developed a PC data-base and a set of analysis programs with graphic capabilities, frequency analysis, as well as an objective way of describing the signals obtained during VEP experiments. PMID:1879131

Mitchell-DePew, J; Ingeholm, J E; Chronister, R J; Pavlopoulos, S; Micheli-Tzanakou, E



Effects of psychotropic drugs on somatosensory evoked potentials in cerebral ischemia.  


Several authors have demonstrated a correlation between short latency somatosensory evoked potentials (short latency SEPs) and cerebral blood flow (CBF). It is also known that ischemia may modify the amplitude of the cortical SEP while its latency is less sensitive to CBF fluctuations. Phychotropic drugs--Oxiracetam, SAMe, Naloxone, L-acetylcarnitine and GM1--affect some parameters of the early components of cortical SEPs, chiefly the amplitude, which makes SEP recording a useful method for monitoring pharmacological activity in acute stroke. PMID:1874607

Monaco, P; Pastore, L; Conti, A



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


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. PMID:24819150

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



Emotional Body-Word Conflict Evokes Enhanced N450 and Slow Potential  

PubMed Central

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.

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



Purinergic modulation of neuronal activity in developing auditory brainstem.  


In the developing nervous system, spontaneous neuronal activity arises independently of experience or any environmental input. This activity may play a major role in axonal pathfinding, refinement of topographic maps, dendritic morphogenesis, and the segregation of axonal terminal arbors. In the auditory system, endogenously released ATP in the cochlea activates inner hair cells to trigger bursts of action potentials (APs), which are transferred to the central auditory system. Here we show the modulatory role of purinergic signaling beyond the cochlea, i.e., the developmentally regulated and cell-type-specific depolarizing effects on auditory brainstem neurons of Mongolian gerbil. We assessed the effects of P2X receptors (P2XRs) on neuronal excitability from prehearing to early stages of auditory signal processing. Our results demonstrate that in neurons expressing P2XRs, extracellular ATP can evoke APs in sync with Ca(2+) signals. In cochlear nucleus (CN) bushy cells, ATP increases spontaneous and also acoustically evoked activity in vivo, but these effects diminish with maturity. Moreover, ATP not only augmented glutamate-driven firing, but it also evoked APs in the absence of glutamatergic transmission. In vivo recordings also revealed that endogenously released ATP in the CN contributes to neuronal firing activity by facilitating AP generation and prolonging AP duration. Given the enhancing effect of ATP on AP firing and confinement of P2XRs to certain auditory brainstem nuclei, and to distinct neurons within these nuclei, it is conceivable that purinergic signaling plays a specific role in the development of neuronal brainstem circuits. PMID:22855818

Dietz, Beatrice; Jovanovic, Saša; Wielsch, Betty; Nerlich, Jana; Rübsamen, Rudolf; Milenkovic, Ivan



Assessment of muscle flap sensibility by evoked potentials in the rat.  


This study investigated whether the sensory-to-motor reinervation of the muscle flap provides a better sensory recovery of an overlying skin graft. Fifty-four animals were studied in three groups of 18 rats each: group I (control): 1 cm of the gastrocnemius muscle motor nerve was excised and no repair was performed; group II (motor-to-motor repair): the motor nerve of the gastrocnemius flap was transected and repaired; group III (sensory-to-motor repair): the motor nerve of the gastrocnemius muscle and sural nerve were transected and their distal and proximal ends, respectively, were repaired. At follow-up periods of 6, 12, and 24 weeks, evaluation of hair growth, muscle atrophy, and sensory evoked potentials was performed. Somatosensory evoked potentials (SSEP) at 6 weeks in the sensory-to-motor repair (group III) revealed a significant (P < 0. 05) increase (104.4% +/- 22.9) in the relative response of peak-to-peak potentials when compared with group I (46.6% +/- 19) and group II (51.8% +/- 14.0). Muscle flap stimulation was most prominent at 6 weeks in sensory-to-motor reinvervated flaps (group III 133.1% +/- 25.4; group I 84.9% +/- 20.2). In this study, sensory-to-motor nerve repair significantly improved the sensibility of skin flaps at 6 weeks. Denervated flaps presented with 3 months of sensory recovery delay. PMID:10702742

Siemionow, M; Latifoglu, O; Demirkan, F; Siemionow, W; Lister, G



Spatial profile of dendritic calcium transients evoked by action potentials in rat neocortical pyramidal neurones.  


1. Simultaneous measurements of intracellular free calcium concentration ([Ca2+]i) and intrasomatic and intradendritic membrane potential (Vm) were performed using fura-2 fluorimetry and whole-cell recording in neocortical layer V pyramidal neurones in rat brain slices. 2. Back-propagating action potentials (APs) evoked [Ca2+]i transients in the entire neurone including the soma, the axon initial segment, the apical dendrite up to the distal tuft branches, and the oblique and basal dendrites, indicating that following suprathreshold activation the entire dendritic tree is depolarized sufficiently to open voltage-dependent calcium channels (VDCCs). 3. The [Ca2+]i transient peak evoked by APs showed large differences between various compartments of the neurone. Following a single AP, up to 6-fold differences were measured, ranging from 43 +/- 14 nM in the soma to 267 +/- 109 nM in the basal dendrites. 4. Along the main apical dendrite, the [Ca2+]i transients evoked by single APs or trains of APs had the largest amplitude and the fastest decay in the proximal region; the [Ca2+]i transient peak and decay time constant following a single AP were 128 +/- 25 nM and 420 +/- 150 ms, respectively, and following a train of five APs (at 10-12 Hz), 710 +/- 214 nM and 390 +/- 150 ms, respectively. The [Ca2+]i transients gradually decreased in amplitude and broadened in more distal portions of the apical dendrite up to the main bifurcation. 5. In the apical tuft branches, the profile of the [Ca2+]i transients was dependent on AP frequency.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8544123

Schiller, J; Helmchen, F; Sakmann, B



Exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials  

NASA Astrophysics Data System (ADS)

Objective. The steady-state visual evoked potential (SSVEP) is an electroencephalographic response to flickering stimuli generated partly in primary visual area V1. The typical ‘cruciform’ geometry and retinotopic organization of V1 is such that certain neighboring visual regions project to neighboring cortical regions of opposite orientation. Here, we explored ways to exploit this organization in order to boost scalp SSVEP amplitude via oscillatory summation. Approach. We manipulated flicker-phase offsets among angular segments of a large annular stimulus in three ways, and compared the resultant SSVEP power to a conventional condition with no temporal phase offsets. (1) We divided the annulus into standard octants for all subjects, and flickered upper horizontal octants with opposite temporal phase to the lower horizontal ones, and left vertical octants opposite to the right vertical ones; (2) we individually adjusted the boundaries between the eight contiguous segments of the standard octants condition to coincide with cruciform-consistent, early-latency topographical shifts in pattern-pulse multifocal visual-evoked potentials (PPMVEP) derived for each of 32 equal-sized segments; (3) we assigned phase offsets to stimulus segments following an automatic algorithm based on the relative amplitudes of vertically- and horizontally-oriented PPMVEP components. Main results. The three flicker-phase manipulations resulted in a significant enhancement of normalized SSVEP power of (1) 202%, (2) 383%, and (3) 300%, respectively. Significance. We have thus demonstrated a means to obtain more reliable measures of visual evoked activity purely through consideration of cortical geometry. This principle stands to impact both basic and clinical research using SSVEPs.

Vanegas, M. Isabel; Blangero, Annabelle; Kelly, Simon P.



Spatial profile of dendritic calcium transients evoked by action potentials in rat neocortical pyramidal neurones.  

PubMed Central

1. Simultaneous measurements of intracellular free calcium concentration ([Ca2+]i) and intrasomatic and intradendritic membrane potential (Vm) were performed using fura-2 fluorimetry and whole-cell recording in neocortical layer V pyramidal neurones in rat brain slices. 2. Back-propagating action potentials (APs) evoked [Ca2+]i transients in the entire neurone including the soma, the axon initial segment, the apical dendrite up to the distal tuft branches, and the oblique and basal dendrites, indicating that following suprathreshold activation the entire dendritic tree is depolarized sufficiently to open voltage-dependent calcium channels (VDCCs). 3. The [Ca2+]i transient peak evoked by APs showed large differences between various compartments of the neurone. Following a single AP, up to 6-fold differences were measured, ranging from 43 +/- 14 nM in the soma to 267 +/- 109 nM in the basal dendrites. 4. Along the main apical dendrite, the [Ca2+]i transients evoked by single APs or trains of APs had the largest amplitude and the fastest decay in the proximal region; the [Ca2+]i transient peak and decay time constant following a single AP were 128 +/- 25 nM and 420 +/- 150 ms, respectively, and following a train of five APs (at 10-12 Hz), 710 +/- 214 nM and 390 +/- 150 ms, respectively. The [Ca2+]i transients gradually decreased in amplitude and broadened in more distal portions of the apical dendrite up to the main bifurcation. 5. In the apical tuft branches, the profile of the [Ca2+]i transients was dependent on AP frequency.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 8 Figure 10

Schiller, J; Helmchen, F; Sakmann, B



Exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials  

PubMed Central

Objective The steady-state visual evoked potential (SSVEP) is an electroencephalographic response to flickering stimuli generated partly in primary visual area V1. The typical “cruciform” geometry and retinotopic organization of V1 is such that certain neighboring visual regions project to neighboring cortical regions of opposite orientation. Here, we explored ways to exploit this organization in order to boost scalp SSVEP amplitude via oscillatory summation. Approach We manipulated flicker-phase offsets among angular segments of a large annular stimulus in three ways, and compared the resultant SSVEP power to a conventional condition with no temporal phase offsets. 1) we divided the annulus into standard octants for all subjects, and flickered upper horizontal octants with opposite temporal phase to the lower horizontal ones, and left vertical octants opposite to the right vertical ones; 2) we individually adjusted the boundaries between the 8 contiguous segments of the standard octants condition to coincide with cruciform-consistent, early-latency topographical shifts in pattern-pulse multifocal visual-evoked potentials (PPMVEP) derived for each of 32 equal-sized segments; 3) we assigned phase offsets to stimulus segments following an automatic algorithm based on the relative amplitudes of vertically- and horizontally-oriented PPMVEP components. Main results The three flicker-phase manipulations resulted in a significant enhancement of normalized SSVEP power of 1) 202%, 2) 383%, and 3) 300%, respectively. Significance We have thus demonstrated a means to obtain more reliable measures of visual evoked activity purely through consideration of cortical geometry. This principle stands to impact both basic and clinical research using SSVEPs.

Vanegas, M Isabel; Blangero, Annabelle; Kelly, Simon P



The impact of synaptic conductance on action potential waveform: evoking realistic action potentials with a simulated synaptic conductance.  


Most current clamp studies trigger action potentials (APs) by step current injection through the recording electrode and assume that the resulting APs are essentially identical to those triggered by orthodromic synaptic inputs. However this assumption is not always valid, particularly when the synaptic conductance is of large magnitude and of close proximity to the axon initial segment. We addressed this question of similarity using the Calyx of Held/MNTB synapse; we compared APs evoked by long duration step current injections, short step current injections and orthodromic synaptic stimuli. Neither injected current protocol evoked APs that matched the evoked orthodromic AP waveform, showing differences in AP height, half-width and after-hyperpolarization. We postulated that this 'error' could arise from changes in the instantaneous conductance during the combined synaptic and AP waveforms, since the driving forces for the respective ionic currents are integrating and continually evolving over this time-course. We demonstrate that a simple Ohm's law manipulation of the EPSC waveform, which accounts for the evolving driving force on the synaptic conductance during the AP, produces waveforms that closely mimic those generated by physiological synaptic stimulation. This stimulation paradigm allows supra-threshold physiological stimulation (single stimuli or trains) without the variability caused by quantal fluctuation in transmitter release, and can be implemented without a specialised dynamic clamp system. Combined with pharmacological tools this method provides a reliable means to assess the physiological roles of postsynaptic ion channels without confounding affects from the presynaptic input. PMID:19560491

Johnston, Jamie; Postlethwaite, Michael; Forsythe, Ian D



The P50 auditory event–evoked potential in adult attention-deficit disorder: comparison with schizophrenia  

Microsoft Academic Search

Background: Attention-deficit\\/hyperactivity disorder (ADHD) and schizophrenia are both conceptualized as disorders of attention. Failure to inhibit the P50 auditory event–evoked response, extensively studied in schizophrenia, could also occur in ADHD patients, if these two illnesses have common underlying neurobiological substrates.Methods: This study examined the inhibition of the P50 auditory event–evoked potential in 16 unmedicated adults with ADHD, 16 schizophrenic outpatients,

Ann Olincy; Randal G Ross; Josette G Harris; David A Young; Mary Ann McAndrews; Ellen Cawthra; Kara A McRae; Bernadette Sullivan; Lawrence E Adler; Robert Freedman



Long sensory tracts (cuneate fascicle) in cervical somatosensory evoked potential after median nerve stimulation.  


Low amplitude high frequency waves (LHW) were investigated in normal and patient cervical somatosensory evoked potentials after median nerve stimulation (CSEP) in parallel to normal and patient conducted somatosensory evoked potentials (SEP) after tibial nerve stimulation. Normal recordings were obtained in five subjects undergoing dorsal root entry zone (DREZ) coagulation for pain relief. Patient recordings were obtained in 11 subjects suffering from either syringomyelia, spinal cord tumour, or both. All recordings were made intraoperatively from the dorsal spinal cord surface using the subpial recording technique. Normal CSEP showed typical triphasic potential starting with an initial P9, followed by N13 and a final positivity, P1. Numerous LHW were superimposed on slow triphasic potential. To improve the visibility of LHW, slow triphasic potential was removed from the original CSEP. Potentials thus obtained contained only high frequency components of CSEP, i.e. LHW. They were compared with conducted SEP after tibial nerve stimulation. Comparison revealed similarities in high frequency, low amplitude and general wave form, LHW thus showing characteristics of conducted potential. Duration was found to be significantly shorter than normal duration in both patient LHW (Student's t-test, P < 0.0005) and patient conducted SEP (Student's t-test, P = 0.064). A shorter duration was associated with worsening of configuration in patient LHW and patient conducted SEP. These changes of LHW could not be connected with distortion of N13 seen in patient CSEP. A shorter duration and worsening of configuration in patient LHW were most prominent in cases with a loss of vibration and posture senses, but were also observed in cases where only pain and temperature senses were affected. We therefore concluded that cuneate fascicle is the most likely generator of LHW, although the participation of other cervical long sensory tracts, e.g. spinothalamic tract, cannot be ruled out. PMID:9402889

Prestor, B; Gnidovec, B; Golob, P



Sensory evoked potentials in unanesthetized unrestrained cuttlefish: a new preparation for brain physiology in cephalopods.  


Up to five microelectrodes inserted through short hypodermic needles in the cranial cartilage of Sepia officinalis recorded potentials while the cuttlefish moved freely in a small enclosure. Compound field potentials and unit spikes were seen during ongoing, spontaneous activity and after sensory stimulation. Ongoing activity resembles that reported for octopus, with maximum power usually below 20 Hz. Amplitude varies greatly but has not been seen to shut off or turn on abruptly and globally as in octopus. Evoked potentials, focally large after flashes of light consist of several waves; the first is largest, positive and peaks at ca. 35 ms (called P35), followed by ca. P75, P95, N110 and smaller waves or oscillations lasting more than 0.5 s. The Upper Following Frequency (highest flashing rate the potentials can follow 1:1), without averaging, is greater than 15 flashes/s (20-22 degrees C); at 20/s the 1:1 following lasts for 1 or 2 s. The Lower Fusion Frequency of averaged responses is less than 30/s. Gentle tapping of the tank wall evokes local, brief, fast potentials. No responses have been found to loud air-borne clicks and tone bursts with principal energy at 300 Hz or to electric fields in the bath at 50-100 microV/cm. In a few loci relatively large slow Omitted Stimulus Potentials have been seen following the end of a train of flashes at more than 5/s; these are by definition event related potentials and a special, central form of OFF response. PMID:2033566

Bullock, T H; Budelmann, B U



Activation of cannabinoid CB1 receptors modulates evoked action potentials in rat retinal ganglion cells.  


Activation of cannabinoid CB1 receptors (CB1Rs) regulates a variety of physiological functions in the vertebrate retina through modulating various types of ion channels. The aim of the present study was to investigate the effects of this receptor on cell excitability of rat retinal ganglion cells (RGCs) in retinal slices using whole-cell patch-clamp techniques. The results showed that under current-clamped condition perfusing WIN55212-2 (WIN, 5 ?mol/L), a CB1R agonist, did not significantly change the spontaneous firing frequency and resting membrane potential of RGCs. In the presence of cocktail synaptic blockers, including excitatory postsynaptic receptor blockers CNQX and D-APV, and inhibitory receptor blockers bicuculline and strychnine, perfusion of WIN (5 ?mol/L) hardly changed the frequencies of evoked action potentials by a series of positive current injection (from +10 to +100 pA). Phase-plane plot analysis showed that both average threshold voltage for triggering action potential and delay time to reach threshold voltage were not affected by WIN. However, WIN significantly decreased +dV/dtmax and -dV/dtmax of action potentials, suggestive of reduced rising and descending velocities of action potentials. The effects of WIN were reversed by co-application of SR141716, a CB1R selective antagonist. Moreover, WIN did not influence resting membrane potential of RGCs with synaptic inputs being blocked. These results suggest that activation of CB1Rs may regulate intrinsic excitability of rat RGCs through modulating evoked action potentials. PMID:23963066

Jiang, Shu-Xia; Li, Qian; Wang, Xiao-Han; Li, Fang; Wang, Zhong-Feng



Effect of graded hypoxia on cortical and spinal somatosensory evoked potentials.  


Cortical somatosensory evoked potential (CSEP), spinal somatosensory evoked potential (SSEP), and electroencephalogram were recorded in rats under pentobarbital anesthesia. After baseline recordings in room air (21% O2), animals were subjected to a graded hypoxia at 15.75%, 10.5%, and 5.25% oxygen levels for 10 minutes. Each level of hypoxia was followed by a 15-minute reoxygenation period. With a moderate hypoxia (15.75% O2), measured latencies for the CSEP and the SSEP were not significantly different compared with baseline (p greater than 0.05). The CSEP amplitude showed a significant increase (p = 0.02) during reoxygenation after the moderate hypoxia. Change in the latency or amplitude of SSEP at 15.75% hypoxia or during the reoxygenation period was not significant compared with the room air (p greater than 0.05). No change in the electroencephalogram was noticed with the moderate hypoxia. At severe hypoxia (10.5% O2), 80% of the animals lost CSEP within 2 minutes. The loss of CSEP was concomitant with significant attenuation of the electroencephalogram waves. The SSEP was resistant to the severe hypoxia and was present in all animals. We concluded that hypoxia affects CSEP with the tendency to increase the amplitude at moderate hypoxia (15.75%) and loss of the latency and amplitude with severe (10.5%) and extreme (5.25%) hypoxia. PMID:1631759

Haghighi, S S; Oro, J J; Gibbs, S R; McFadden, M



Diminished n1 auditory evoked potentials to oddball stimuli in misophonia patients.  


Misophonia (hatred of sound) is a newly defined psychiatric condition in which ordinary human sounds, such as breathing and eating, trigger impulsive aggression. In the current study, we investigated if a dysfunction in the brain's early auditory processing system could be present in misophonia. We screened 20 patients with misophonia with the diagnostic criteria for misophonia, and 14 matched healthy controls without misophonia, and investigated any potential deficits in auditory processing of misophonia patients using auditory event-related potentials (ERPs) during an oddball task. Subjects watched a neutral silent movie while being presented a regular frequency of beep sounds in which oddball tones of 250 and 4000?Hz were randomly embedded in a stream of repeated 1000?Hz standard tones. We examined the P1, N1, and P2 components locked to the onset of the tones. For misophonia patients, the N1 peak evoked by the oddball tones had smaller mean peak amplitude than the control group. However, no significant differences were found in P1 and P2 components evoked by the oddball tones. There were no significant differences between the misophonia patients and their controls in any of the ERP components to the standard tones. The diminished N1 component to oddball tones in misophonia patients suggests an underlying neurobiological deficit in misophonia patients. This reduction might reflect a basic impairment in auditory processing in misophonia patients. PMID:24782731

Schröder, Arjan; van Diepen, Rosanne; Mazaheri, Ali; Petropoulos-Petalas, Diamantis; Soto de Amesti, Vicente; Vulink, Nienke; Denys, Damiaan



Diminished N1 Auditory Evoked Potentials to Oddball Stimuli in Misophonia Patients  

PubMed Central

Misophonia (hatred of sound) is a newly defined psychiatric condition in which ordinary human sounds, such as breathing and eating, trigger impulsive aggression. In the current study, we investigated if a dysfunction in the brain’s early auditory processing system could be present in misophonia. We screened 20 patients with misophonia with the diagnostic criteria for misophonia, and 14 matched healthy controls without misophonia, and investigated any potential deficits in auditory processing of misophonia patients using auditory event-related potentials (ERPs) during an oddball task. Subjects watched a neutral silent movie while being presented a regular frequency of beep sounds in which oddball tones of 250 and 4000?Hz were randomly embedded in a stream of repeated 1000?Hz standard tones. We examined the P1, N1, and P2 components locked to the onset of the tones. For misophonia patients, the N1 peak evoked by the oddball tones had smaller mean peak amplitude than the control group. However, no significant differences were found in P1 and P2 components evoked by the oddball tones. There were no significant differences between the misophonia patients and their controls in any of the ERP components to the standard tones. The diminished N1 component to oddball tones in misophonia patients suggests an underlying neurobiological deficit in misophonia patients. This reduction might reflect a basic impairment in auditory processing in misophonia patients.

Schroder, Arjan; van Diepen, Rosanne; Mazaheri, Ali; Petropoulos-Petalas, Diamantis; Soto de Amesti, Vicente; Vulink, Nienke; Denys, Damiaan



Topographic analysis of laser evoked potentials in chronic tension-type headache: correlations with clinical features.  


In the present study, we examined clinical and laser-evoked potentials (LEP) features in a group of chronic tension-type headache (CTTH) patients, in order to perform a topographic analysis of Laser evoked potentials (LEPs) and a correlation with clinical features. Eighteen patients suffering from CTTH [Headache Classification Subcommittee of the International Headache Society. The International Classification of Headache Disorders 2nd ed. Cephalalgia 2004; 24 Suppl 1, 1-159.] participated in the study. Twelve age- and sex-matched controls were also examined. We performed a basal evaluation of clinical features, Total Tenderness Score (TTS) and a topographic analysis of LEPs obtained by the hand and the pericranial points stimulation in all patients vs healthy subjects. The later LEPs, especially the P2 component, were significantly increased in amplitude in the CTTH group, specially when the pericranial points were stimulated. The P2 wave amplitude was correlated with TTS levels and anxiety scores. The results of this study confirm that pericranial tenderness is a phenomenon initiating a self-sustaining circuit, involving central sensitization at the level of the cortical nociceptive areas devoted to attentional and emotional components of pain. PMID:16503063

de Tommaso, Marina; Shevel, Elliott; Pecoraro, Carla; Sardaro, Michele; Losito, Luciana; Lamberti, Paolo; Livrea, Paolo



Combined Muscle Motor and Somatosensory Evoked Potentials for Intramedullary Spinal Cord Tumour Surgery  

PubMed Central

Purpose To evaluate whether intraoperative neurophysiologic monitoring (IONM) with combined muscle motor evoked potentials (mMEPs) and somatosensory evoked potentials is useful for more aggressive and safe resection in intramedullary spinal cord tumour (IMSCT) surgery. Materials and Methods We reviewed data from consecutive patients who underwent surgery for IMSCT between 1998 and April 2012. The patients were divided into two groups based on whether or not IONM was applied. In the monitored group, the procedures were performed under IONM using 75% muscle amplitude decline weaning criteria. The control group was comprised of patients who underwent IMSCT surgery without IONM. The primary outcome was the rate of gross total excision of the tumour on magnetic resonance imaging at one week after surgery. The secondary outcome was the neurologic outcome based on the McCormick Grade scale. Results The two groups had similar demographics. The total gross removal tended to increase when intraoperative neurophysiologic monitoring was used, but this tendency did not reach statistical significance (76% versus 58%; univariate analysis, p=0.049; multivariate regression model, p=0.119). The serial McCormick scale score was similar between the two groups (based on repeated measure ANOVA). Conclusion Our study evaluated combined IONM of trans-cranial electrical (Tce)-mMEPs and SEPs for IMSCT. During IMSCT surgery, combined Tce-mMEPs and SEPs using 75% muscle amplitude weaning criteria did not result in significant improvement in the rate of gross total excision of the tumour or neurologic outcome.

Choi, Il; Hyun, Seung-Jae; Kang, Joong-Koo



The diagnostic significance of the multifocal pattern visual evoked potential in glaucoma.  


The concept of objective perimetry is an exciting one because it strives to assess glaucoma damage without relying on psychophysical testing. The recent introduction of multifocal stimulus recording has enhanced our ability to examine the human visual field using electrophysiology. A multifocal pattern visual evoked potential can now be recorded, testing up to 60 sites within the central 25 degrees. The test requires only that the subject fixate on a target, while a cortically scaled dartboard pattern stimulus undergoes pseudorandom alternation within each of the test segments. In its present configuration the test requires at least 8 minutes recording time per eye. Modified bipolar electrode positions are required to ensure that adequate signals are detected from all parts of the visual field. In glaucoma patients, pattern visual evoked potential amplitudes have been shown to reflect visual field loss with reduction of signal amplitude in the affected areas. This technique represents the first major step toward objective detection of visual field defects in glaucoma. PMID:10537765

Graham, S L; Klistorner, A



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


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. PMID:1786787

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



Childhood multiple sclerosis (MS): multimodal evoked potentials (EP) and magnetic resonance imaging (MRI) comparative study.  


We compared the diagnostic sensitivity of magnetic resonance imaging (MRI) and evoked potential (EP) studies in a series of 19 children affected by clinically definite (16 cases) and laboratory supported (3 cases) multiple sclerosis (MS). MRI revealed abnormal areas consistent with demyelinating plaques in 18 out of 19 cases: multiple lesions in 16 and an isolated lesion in 2 cases. Abnormal areas were more frequently found in supratentorial regions than in other areas of the central nervous system. In all patients, the distribution, form and topography of the lesions were typical of MS and similar to those found in the adult form of the disease. Multimodal EP were abnormal in 16 out of 19 cases. Visual (VEP) and somatosensory evoked potentials (SEP) abnormalities were frequently asymptomatic and VEPs were particularly sensitive in ascertaining childhood MS. MRI was slightly more sensitive than multimodal EP in confirming the clinical diagnosis of childhood MS. However, in suspected or probable MS with normal MRI, VEPs and SEPs may contribute to the definition of clinical diagnosis because of their capacity to demonstrate asymptomatic involvement in central nervous system (CNS) the optic nerve and central somatosensory pathways). PMID:2038422

Scaioli, V; Rumi, V; Cimino, C; Angelini, L



Real time mapping of rat midbrain neural circuitry using auditory evoked potentials.  


Auditory evoked potentials were recorded in 360 homogeneously spaced sites, in a volume encapsulating the lateral lemniscus-inferior colliculus transition of anaesthetized rats, in order to calculate the electric field vector distribution with each moment in time referenced to the onset of sound presentation. Software, to conduct calculations and graphical representation, and hardware, to minimize neural damage upon recording, were developed in our laboratory. Our results indicate a smooth transition of both amplitude and direction of vectors, suggestive of sequentially activated sites with outward and inward ionic currents coherent with what is known of this part of the primary auditory pathway. That is, anatomical sites (neural generators) and latency for activation matches previous research of the auditory pathway, while adding a real time perspective to the anatomical substrates recruited during the auditory evoked response. An algorithm for calculating the divergent of the vector field, an estimate of the current source density inside the three-dimensional control volume, was used to infer the possible current sinks and sources generating the field potentials. This technique allowed a clear visualization of two distinct discharges arising from the lateral lemniscus towards the inferior colliculus, thus recording signal propagation, as a movie file, with 0.06 ms time resolution. PMID:11744279

Moraes, M F; Garcia-Cairasco, N



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

PubMed Central

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.

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



Effect of Test Duration on the Visual-Evoked Potential (VEP) and Alpha Wave Responses  

PubMed Central

Primary objective The purpose of this study was to assess the effect of test duration on the visual-evoked potential (VEP) and related alpha power spectrum measures. Design and methods Two conditions (eyes-closed and eyes-open) were tested using four different durations: ten, twenty, forty-five, and sixty seconds. The Diopsys™ NOVA-TR system was used to obtain the visual-evoked potential (VEP) and extracted alpha-wave with its related power spectrum. 16 visually-normal, young-adult subjects (ages 22 to 25 years) participated in the experiment. The stimulus for the eyes-open condition consisted of a black-and-white, alternating checkerboard pattern with a small central fixation target. All trials were performed during one session. Results Regarding the VEP parameters, only variability of the VEP amplitude changed significantly with test duration: it decreased with increasing test duration, with the 45 and 60 second trials showing similarly low variability. Regarding the alpha wave parameters, test duration did not have a significant effect on either the mean alpha power or its variability across trials. Conclusions The findings demonstrate that forty-five second test durations are sufficient to minimize intra-session variability of the VEP amplitude and latency measurements, whereas several 10 second test durations may be sufficient for accurate measurement of the alpha wave. Optimization of test duration allows for repeatable measures with less total test time. This is especially important for special clinical populations.

Willeford, Kevin T.; Ciuffreda, Kenneth J.; Yadav, Naveen K.



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


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

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



Painful stimuli evoke potentials recorded from the medial temporal lobe in humans  

PubMed Central

The role of human medial temporal structures in fear conditioning has led to the suggestion that neurons in these structures might respond to painful stimuli. We have now tested the hypothesis that recordings from these structures will demonstrate potentials related to the selective activation of cutaneous nociceptors by a painful laser stimulus (laser evoked potential, LEP)(Kenton et al., 1980). Recordings were carried out through electrodes implanted bilaterally in these structures for the investigation of intractable epilepsy. Reproducible LEPs were commonly recorded both bilaterally and unilaterally, while LEPs were recorded at contacts on the left (9/14, P=0.257) as commonly as on the right (5/14), independent of the hand stimulated. Along electrodes traversing the amygdala the majority of LEPs were recorded from dorsal contacts near the central nucleus of the amygdala and the nucleus basalis. Stimulus evoked changes in theta activity were observed at contacts on the right at which isolated early negative LEPs (N2*) responses could be recorded. Contacts at which LEPs could be recorded were as commonly located in medial temporal structures with evidence of seizure activity as on those without. These results demonstrate the presence of pain-related inputs to the medial temporal lobe where they may be involved in associative learning to produce anxiety and disability related to painful stimuli.

Liu, C.C.; Ohara, S.; Franaszczuk, P.; Zagzoog, N.; Gallagher, M.; Lenz, F.A.



Auditory evoked potential (AEP) measurements in stranded rough-toothed dolphins (Steno bredanensis)  

NASA Astrophysics Data System (ADS)

Thirty-six rough-toothed dolphins (Steno bredanensis) live-stranded on Hutchinson Island, FL on August 6, 2004. Seven animals were transported to Mote Marine Laboratory for rehabilitation. Two auditory evoked potential (AEP) measurements were performed on each of five of these dolphins in air using a jawphone to present acoustic stimuli. Modulation rate transfer functions (MRTFs) were measured to establish how well the auditory system follows the temporal envelope of acoustic stimuli. A 40 kHz stimulus carrier was amplitude modulated (AM) with varying rates ranging from 200 Hz to 1800 Hz, in 200 Hz steps. The best AM-rate from the first dolphin tested was 1500 Hz. This AM rate was used in subsequent AEP measurements to determine evoked-potential hearing thresholds between 5000 and 80000 Hz. These findings show that rough-toothed dolphins can detect sounds between 5 and 80 kHz, and are most likely capable of detecting frequencies much higher than 80 kHz. MRTF data suggest that rough-toothed dolphins have a high temporal resolution, similar to that of other cetaceans.

Cook, Mandy L. H.; Manire, Charles A.; Mann, David A.



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


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. PMID:22484484

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



Neurophysiological characteristics of human leg muscle action potentials evoked by transcutaneous magnetic stimulation of the spine.  


The objectives of this study were to establish the neurophysiological properties of the compound muscle action potentials (CMAPs) evoked by transcutaneous magnetic stimulation of the spine (tsMSS) and the effects of tsMSS on the soleus H-reflex. In semi-prone seated subjects with trunk semi-flexed, the epicenter of a figure-of-eight magnetic coil was placed at Thoracic 10 with the handle on the midline of the vertebral column. The magnetic stimulator was triggered by monophasic single pulses of 1?ms, and the intensity ranged from 90% to 100% of the stimulator output across subjects. CMAPs were recorded bilaterally from ankle and knee muscles at the interstimulus intervals of 1, 3, 5, 8, and 10?s. The CMAPs evoked were also conditioned by posterior tibial and common peroneal nerve stimulation at a conditioning-test (C-T) interval of 50?ms. The soleus H-reflex was conditioned by tsMSS at the C-T intervals of 50, 20, -20, and -50?ms. The amplitude of the CMAPs was not decreased when evoked at low stimulation frequencies, excitation of group I afferents from mixed peripheral nerves in the leg affected the CMAPs in a non-somatotopical neural organization pattern, and tsMSS depressed soleus H-reflex excitability. These CMAPs are likely due to orthodromic excitation of nerve motor fibers and antidromic depolarization of different types of afferents. The latency of these CMAPs may be utilized to establish the spine-to-muscle conduction time in central and peripheral nervous system disorders in humans. tsMSS may constitute a non-invasive modality to decrease spinal reflex hyperexcitability and treat hypertonia in neurological disorders. PMID:23192827

Knikou, Maria



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

PubMed Central

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+].

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



Dendritic calcium transients evoked by single back-propagating action potentials in rat neocortical pyramidal neurons.  


1. Dendrites of rat neocortical layer V pyramidal neurons were loaded with the Ca2+ indicator dye Calcium Green-1 (CG-1) or fluo-3, and the mechanisms which govern action potential (AP)-evoked transient changes in dendritic cytosolic Ca2+ concentration ([Ca2+]i) were examined. APs were initiated either by synaptic stimulation or by depolarizing the soma or dendrite by current injection, and changes in fluorescence of the indicator dye were measured in the proximal 170 microns of the apical dendrite. 2. Simultaneous two-pipette recordings of APs from the soma and apical dendrite, and dendritic fluorescence imaging indicated that a single AP propagating from the soma into the apical dendrite evokes a rapid transient increase in fluorescence indicating a transient increase in [Ca2+]i. At 35-37 degrees C the decay time constant of the fluorescence transient following an AP was around 80 ms. 3. Voltage-activated Ca2+ channels (VACCs) of several subtypes mediated the AP-evoked fluorescence transient in the proximal (100-170 microns) apical dendrite. The AP-evoked fluorescence transient resulted from Ca2+ entry through L-type (nifedipine sensitive; 25%), N-type (omega-conotoxin GVIA sensitive; 28%) and P-type (omega-agatoxin IVA sensitive; 10%) Ca2+ channels and through Ca2+ channels (R-type) not sensitive to L-, N- and P-type Ca2+ channel blockers (cadmium ion sensitive; 37%). 4. The decay time course of the dendritic fluorescence transient was prolonged by the blockers of endoplasmic reticulum (ER) Ca(2+)-ATPase, cyclopiazonic acid and thapsigargin, suggesting that uptake of Ca2+ into the ER in dendrites governs clearance of dendritic Ca2+. 5. The decay time course of the fluorescence transient was slightly prolonged by benzamil, a blocker of plasma membrane Na(+)-Ca2+ exchange and by calmidazolium, a blocker of the calmodulin-dependent plasma membrane Ca(2+)-ATPase, suggesting that these pathways are less important for dendrite Ca2+ clearance following a single AP. Neither the mitochondrial uncoupler carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) nor the blocker of Ca2+ uptake into mitochondria, Ruthenium Red, had any measurable effect on the decay time course of the fluorescence transient. 6. Dendritic fluorescence transients measured during trains of dendritic APs began to summate at impulse frequencies of 5 APs s-1. At higher frequencies APs caused a concerted and maintained elevation of dendritic fluorescence during the train.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7658365

Markram, H; Helm, P J; Sakmann, B



Comparison of visually evoked local field potentials in isolated turtle brain: patterned versus blank stimulation.  


Isolated turtle brain/eye preparation has recently been used as a bloodless animal model for detecting the magnetic resonance imaging (MRI) signal changes produced by visually evoked neuronal currents. The present work aims to determine whether checkerboard-patterned or full field flash (blank) stimulation should be used in order to achieve stronger neuronal responses in turtle brain/eye preparation. The knowledge gained in this study is essential for optimizing the visual stimulation methods in functional neuroimaging studies using turtle brain/eye preparation. In this study, visually evoked local field potentials (LFPs) were measured and compared in turtle visual cortex and optic tectum elicited by checkerboard and full field flash stimuli with three different inter-stimulus intervals (ISIs=5, 10, and 16s). It was found that the behavior of neuronal adaptation in the cortical and tectal LFP signals for checkerboard stimulation was comparable to flash stimulation. In addition, there was no significant difference in the LFP peak amplitudes (ISI=16s) between these two stimuli. These results indicate that the intensity of neuronal responses to checkerboard is comparable to flash stimulation. These two stimulation methods should be equivalent in functional neuroimaging studies using turtle brain/eye preparation. PMID:20034520

Luo, Qingfei; Lu, Huo; Lu, Hanbing; Yang, Yihong; Gao, Jia-Hong



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


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. PMID:6194961

Scherg, M; Volk, S A



Improving the acquisition of nociceptive evoked potentials without causing more pain.  


Following nociceptive heat or laser stimulation, an early contralateral and later vertex potential can be recorded. Although more indicative of the nociceptive input, the acquisition of the contralateral N1 after contact heat stimulation (contact heat-evoked potentials [CHEPs]) remains difficult. An advantage of contact heat is that the baseline skin temperature preceding peak stimulation can be controlled. Increasing the baseline temperature may represent a novel strategy to improve the acquisition of CHEPs without resulting in more subjective pain to stimulation. A study was undertaken in 23 healthy subjects to examine the effects of increasing the baseline temperature but not the perceived intensity of contact heat stimulation. A combined standard averaging and single-trial analysis was performed to disclose how changes in averaged waveforms related to latency jitter and individual trial amplitudes. By increasing the baseline temperature, the acquisition of N1 was improved among subjects with a low-amplitude response (greater than -4?V) following 35°C baseline temperature stimulation (P<.05). Based on standard averaging, N2/P2 amplitudes were also significantly increased with and without an accompanying change in the rating of perceived pain when the baseline temperature was increased (P<.05). In contrast, automated single-trial averaging revealed no significant difference in N2 amplitude when the baseline temperature was increased to 42°C and the peak temperature reduced. These findings suggest that 2 mechanisms underlie the improved acquisition of CHEPs: increased synchronization of afferent volley, yielding larger-amplitude evoked potentials in response to the same rating of intensity; and reduced inter-trial variability. PMID:23218174

Kramer, John L K; Haefeli, Jenny; Jutzeler, Catherine R; Steeves, John D; Curt, Armin



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

PubMed Central

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

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



Source localisation of 62-electrode human laser pain evoked potential data using a realistic head model.  


Laser evoked potentials (LEPs), elicited by painful laser stimulation of the right forearm, were recorded from 62 electrodes in a single healthy subject. The positions of the electrodes on the scalp were co-registered with the subject's structural magnetic resonance image (MRI) of the brain. Spatio-temporal dipole modelling, using a head model derived from the MRI, estimated sources in left posterior cingulate, posterior parietal and anterior insular cortices. The parietal source peaked in activity at 260 ms, which explained the N1/N2 peaks of the LEPs. The cingulate source was the most strongly activated, at 400 ms, and accounted for the P2 LEP component. The insular source showed late, prolonged activation, peaking in magnitude at 850 ms. This is the first study to report scalp-recorded LEP generators in posterior parietal and insular cortices. Although these sources require replication, they are consistent with other functional imaging studies. PMID:11325463

Bentley, D E; Youell, P D; Crossman, A R; Jones, A K



Targeting Pain-evoking Transient Receptor Potential Channels for the Treatment of Pain.  


Chronic pain affects billions of lives globally and is a major public health problem in the United States. However, pain management is still a challenging task due to a lack of understanding of the fundamental mechanisms of pain. In the past decades transient receptor potential (TRP) channels have been identified as molecular sensors of tissue damage and inflammation. Activation/sensitization of TRP channels in peripheral nociceptors produces neurogenic inflammation and contributes to both somatic and visceral pain. Pharmacological and genetic studies have affirmed the role of TRP channels in multiple forms of inflammatory and neuropathic pain. Thus pain-evoking TRP channels emerge as promising therapeutic targets for a wide variety of pain and inflammatory conditions. PMID:24396340

Luo, Jialie; Walters, Edgar T; Carlton, Susan M; Hu, Hongzhen



Chronic trichloroethylene intoxication: a new approach by trigeminal-evoked potentials?  


Trigeminal nerve impairment is frequently seen in chronic trichlorethylene intoxication (TRI). A total of 104 occupationally exposed subjects were selected for study because they were employed at a highly exposed workplace. They were studied by clinical examination and by trigeminal somatosensory evoked potentials (TSEP). Normal values for TSEP were obtained from the study of 52 healthy nonexposed subjects. Facial hypoesthesia, when present, was global and predominant in the mandibular and maxillary nerve areas, associated or not with absent reflexes. A disturbed TSEP was found in 40 subjects which was predictable from their clinical symptoms. Correlation with exposure parameters (duration of exposure, trichlorethanol, and trichloracetic acid urinary rates) was mainly observed in subjects presenting both clinical and electrical alterations. Electrical alterations alone were less predictive. An abnormal TSEP may thus provide objective determination of risk assessment in the absence of clinical signs. PMID:3452297

Barret, L; Garrel, S; Danel, V; Debru, J L



The N2-P3 complex of the evoked potential and human performance  

NASA Technical Reports Server (NTRS)

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.

Odonnell, Brian F.; Cohen, Ronald A.



Fronto-parietal evoked potential synchronization is increased during mental rotation.  


We used steady state visually evoked potential event related partial coherence (SSVEP-ERPC) to examine the SSVEP synchronization between brain regions while 22 males undertook a sequential version of the Shepard and Metzler mental rotation task. Compared to the 60 degrees rotation, the 180 degrees rotation was associated with increased synchronization between bilateral prefrontal and parieto-occipital sites, between left frontal and right parietal sites and between bilateral parietal and occipital sites. We suggest that the increased synchronization between prefrontal and parieto-occipital regions may be associated with the working memory components of the task, while the left frontal to right parietal synchronization may represent the increased interaction between these regions thought to occur in a variety of visuo-motor tasks. PMID:12544833

Silberstein, Richard B; Danieli, Frank; Nunez, Paul L



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


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. PMID:4084912

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



Measurement and definition of changes in the visual evoked potential to different stimulus intensities.  


Visual evoked potentials (VEPs) were recorded from the vertex to 5 intensities of light flashes. Measures were taken of peak-to-trough, prestimulus baseline-to-peak, and timeband amplitude for P1, N1, and P2 waveforms. Augmenting/reducing was defined by traditional (amplitude/intensity slope, monotonicity) and non-traditional (strength of the nervous system, combined amplitude response) criteria. In support of Connolly and Gruzelier ([1982) Psychophysiology, 19: 599-608], analyses showed that data collected by traditional methods contravened assumptions underlying VEP augmenting/reducing methodology. Specifically, 20% of total peaks occurred outside designated timebands, amplitude/intensity slopes explained only 30-46% variance, and levels of agreement between different definitions were low. Researchers ought to ensure that VEPs are admissible before using them or consider employing non-traditional criteria to avoid rejecting large numbers of inadmissible data. PMID:3610728

Dragutinovich, S



Abnormal visual-evoked potentials in leukemic children after cranial radiation  

SciTech Connect

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.

Russo, A.; Tomarchio, S.; Pero, G.; Consoli, G.; Marina, R.; Rizzari, C.; Schiliro, G.



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

PubMed Central

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.



Addition of visual noise boosts evoked potential-based brain-computer interface  

PubMed Central

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.

Xie, Jun; Xu, Guanghua; Wang, Jing; Zhang, Sicong; Zhang, Feng; Li, Yeping; Han, Chengcheng; Li, Lili



Motor evoked potentials in the preoperative and postoperative assessment of normal pressure hydrocephalus.  


Motor evoked potentials and central motor conduction time (CMCT) were examined from both upper and lower limbs in patients with normal pressure hydrocephalus to find a predictor for the success of shunting procedures. The hypotheses that walking disturbances are due to pyramidal tract compression as well as the possibility that the upper limbs are affected subclinically in these patients were also studied. The study suggests that the walking disturbances are not the result of a major pyramidal tract dysfunction but probably involve the sensorimotor integration leading to normal gait. Furthermore, CMCT measured with electromagnetic motor stimulation can help in selecting the patients that will benefit from shunting. The study does not provide electrophysiological evidence of upper limb involvement in normal pressure hydrocephalus. PMID:9153613

Zaaroor, M; Bleich, N; Chistyakov, A; Pratt, H; Feinsod, M



Motor evoked potentials in the preoperative and postoperative assessment of normal pressure hydrocephalus.  

PubMed Central

Motor evoked potentials and central motor conduction time (CMCT) were examined from both upper and lower limbs in patients with normal pressure hydrocephalus to find a predictor for the success of shunting procedures. The hypotheses that walking disturbances are due to pyramidal tract compression as well as the possibility that the upper limbs are affected subclinically in these patients were also studied. The study suggests that the walking disturbances are not the result of a major pyramidal tract dysfunction but probably involve the sensorimotor integration leading to normal gait. Furthermore, CMCT measured with electromagnetic motor stimulation can help in selecting the patients that will benefit from shunting. The study does not provide electrophysiological evidence of upper limb involvement in normal pressure hydrocephalus.

Zaaroor, M; Bleich, N; Chistyakov, A; Pratt, H; Feinsod, M



Time-frequency analysis of visual evoked potentials by means of matching pursuit with chirplet atoms.  


Detection of visual evoked potentials (VEP) elicited by repetitive stimuli is valuable in both laboratorial research and clinical practice. Therefore, knowing the characteristics of VEPs is of fundamental importance for adequate design of a signal detector. Usually, the signal is modeled as a steady-state VEP (ssVEP) consisting of the fundamental frequency and the higher harmonics, while ignoring the information contained in its transients (tVEP). We propose here to characterize both tVEP and ssVEP by chirplet time-frequency representation of VEP signal using a matching pursuit (MP) algorithm. Compared to the time-frequency analysis with short-time-Fourier-transform (STFT) and linear-prediction-coding (LPC) method, MP with chirplet shows not only clear characteristics of ssVEP, but a clear spindle-like time-frequency component of tVEP as well, which is not obvious in the other two methods. PMID:17271661

Cui, J; Wong, W; Mann, S



Targeting Pain-evoking Transient Receptor Potential Channels for the Treatment of Pain  

PubMed Central

Chronic pain affects billions of lives globally and is a major public health problem in the United States. However, pain management is still a challenging task due to a lack of understanding of the fundamental mechanisms of pain. In the past decades transient receptor potential (TRP) channels have been identified as molecular sensors of tissue damage and inflammation. Activation/sensitization of TRP channels in peripheral nociceptors produces neurogenic inflammation and contributes to both somatic and visceral pain. Pharmacological and genetic studies have affirmed the role of TRP channels in multiple forms of inflammatory and neuropathic pain. Thus pain-evoking TRP channels emerge as promising therapeutic targets for a wide variety of pain and inflammatory conditions

Luo, Jialie; Walters, Edgar T.; Carlton, Susan M.; Hu, Hongzhen



Addition of visual noise boosts evoked potential-based brain-computer interface.  


Although noise has a proven beneficial role in brain functions, there have not been any attempts on the dedication of stochastic resonance effect in neural engineering applications, especially in researches of brain-computer interfaces (BCIs). In our study, a steady-state motion visual evoked potential (SSMVEP)-based BCI with periodic visual stimulation plus moderate spatiotemporal noise can achieve better offline and online performance due to enhancement of periodic components in brain responses, which was accompanied by suppression of high harmonics. Offline results behaved with a bell-shaped resonance-like functionality and 7-36% online performance improvements can be achieved when identical visual noise was adopted for different stimulation frequencies. Using neural encoding modeling, these phenomena can be explained as noise-induced input-output synchronization in human sensory systems which commonly possess a low-pass property. Our work demonstrated that noise could boost BCIs in addressing human needs. PMID:24828128

Xie, Jun; Xu, Guanghua; Wang, Jing; Zhang, Sicong; Zhang, Feng; Li, Yeping; Han, Chengcheng; Li, Lili



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


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

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



Multimodal Characterization of Population Responses Evoked by Applied Electric Field in vitro: Extracellular Potential, Magnetic Evoked Field, Transmembrane Potential, and Current-Source Density Analysis  

Microsoft Academic Search

An external electric field applied parallel to longitudinal axis of neurons selectively depolarizes either end and thereby activates voltage-sensitive conductance changes in a large population of neurons. Here, we characterized such popu- lation responses in the in vitro turtle cerebellum. The re- sponses were recorded and analyzed using a multimodal approach: the magnetic evoked field was measured using a Superconducting

Luisa Lopez; Christopher Y. Chan; Yoshio C. Okada; Charles Nicholson


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

PubMed Central

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.

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



Trigeminal evoked potential-monitored thermorhizotomy: a novel approach for relief of trigeminal pain.  


This paper presents a complete method for performing trigeminal thermorhizotomy, guided by neurophysiological data, to relieve tic douloureux. The method involves the use of trigeminal evoked potentials (TEPs) produced by stimulation of the supraorbital, infraorbital, and mental nerves and recorded from electrodes at both the scalp and the trigeminal nerve. To perform the thermorhizotomy, a cannula is modified to produce a concentric bipolar electrode that is suitable for both recording and lesion making. The operating procedure is divided into five steps: Step 1, recording of baseline scalp TEPs from the derivation of the cervical vertex to C-7 to ensure that all stimulating electrodes are correctly placed; Step 2, recording of TEPs from the trigeminal electrode after stimulation of the peripheral nerve trunks to ascertain the electrode's position relative to the root bundles; Step 3, fine positioning of the trigeminal electrode by recording the root activity evoked by stimulation of cutaneous trigger points or of the most painful areas; Step 4, assessing the position of the trigeminal electrode relative to the motor root by stimulating the nerve via the electrode and observing the masseter motor responses; and Step 5, recording scalp TEPs immediately before and after each thermolesion. Thermolesions are made until the scalp-recorded wave W2 decreases its amplitude by 20% to 50% of the original value or until it is delayed by 0.30 msec. This procedure has the potential to enable extremely precise monitoring of the position of the trigeminal electrode relative to the activated fibers and provides very effective monitoring of the extent of the lesion. The authors have performed this procedure with very satisfactory results in 30 patients with trigeminal neuralgia in the second branch. PMID:8847586

Leandri, M; Gottlieb, A



Transcutaneous electrical nerve stimulation effects on neglect: a visual-evoked potential study.  


We studied the effects of transcutaneous electrical nerve stimulation (TENS) in six right-brain-damaged patients with left unilateral spatial neglect (USN), using both standard clinical tests (reading, line, and letter cancelation, and line bisection), and electrophysiological measures (steady-state visual-evoked potentials, SSVEP). TENS was applied on left neck muscles for 15', and measures were recorded before, immediately after, and 60' after stimulation. Behavioral results showed that the stimulation temporarily improved the deficit in all patients. In cancelation tasks, omissions and performance asymmetries between the two hand-sides were reduced, as well as the rightward deviation in line bisection. Before TENS, SSVEP average latency to stimuli displayed in the left visual half-field [LVF (160?ms)] was remarkably longer than to stimuli shown in the right visual half-field [RVF (120?ms)]. Immediately after TENS, latency to LVF stimuli was 130?ms; 1?h after stimulation the effect of TENS faded, with latency returning to baseline. TENS similarly affected also the latency SSVEP of 12 healthy participants, and their line bisection performance, with effects smaller in size. The present study, first, replicates evidence concerning the positive behavioral effects of TENS on the manifestations of left USN in right-brain-damaged patients; second, it shows putatively related electrophysiological effects on the SSVEP latency. These behavioral and novel electrophysiological results are discussed in terms of specific directional effects of left somatosensory stimulation on egocentric coordinates, which in USN patients are displaced toward the side of the cerebral lesion. Showing that visual-evoked potentials latency is modulated by proprioceptive stimulation, we provide electrophysiological evidence to the effect that TENS may improve some manifestations of USN, with implications for its rehabilitation. PMID:23966919

Pitzalis, Sabrina; Spinelli, Donatella; Vallar, Giuseppe; Di Russo, Francesco



Transcutaneous Electrical Nerve Stimulation Effects on Neglect: A Visual-Evoked Potential Study  

PubMed Central

We studied the effects of transcutaneous electrical nerve stimulation (TENS) in six right-brain-damaged patients with left unilateral spatial neglect (USN), using both standard clinical tests (reading, line, and letter cancelation, and line bisection), and electrophysiological measures (steady-state visual-evoked potentials, SSVEP). TENS was applied on left neck muscles for 15?, and measures were recorded before, immediately after, and 60? after stimulation. Behavioral results showed that the stimulation temporarily improved the deficit in all patients. In cancelation tasks, omissions and performance asymmetries between the two hand-sides were reduced, as well as the rightward deviation in line bisection. Before TENS, SSVEP average latency to stimuli displayed in the left visual half-field [LVF (160?ms)] was remarkably longer than to stimuli shown in the right visual half-field [RVF (120?ms)]. Immediately after TENS, latency to LVF stimuli was 130?ms; 1?h after stimulation the effect of TENS faded, with latency returning to baseline. TENS similarly affected also the latency SSVEP of 12 healthy participants, and their line bisection performance, with effects smaller in size. The present study, first, replicates evidence concerning the positive behavioral effects of TENS on the manifestations of left USN in right-brain-damaged patients; second, it shows putatively related electrophysiological effects on the SSVEP latency. These behavioral and novel electrophysiological results are discussed in terms of specific directional effects of left somatosensory stimulation on egocentric coordinates, which in USN patients are displaced toward the side of the cerebral lesion. Showing that visual-evoked potentials latency is modulated by proprioceptive stimulation, we provide electrophysiological evidence to the effect that TENS may improve some manifestations of USN, with implications for its rehabilitation.

Pitzalis, Sabrina; Spinelli, Donatella; Vallar, Giuseppe; Di Russo, Francesco