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1

Brainstem Auditory Evoked Potential Study in Children with Autistic Disorder.  

ERIC Educational Resources Information Center

Brainstem auditory evoked potentials were compared in 109 children with infantile autism, 38 with autistic condition, 19 with mental retardation, and 20 normal children. Children with infantile autism or autistic condition had significantly longer brainstem transmission time than normal children suggesting neurological damage as the basis of…

Wong, Virginia; Wong, Sik Nin

1991-01-01

2

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. PMID:21458557

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

2011-01-01

3

Brainstem auditory-evoked potentials in two meditative mental states  

PubMed Central

Context: Practicing mental repetition of “OM” has been shown to cause significant changes in the middle latency auditory-evoked potentials, which suggests that it facilitates the neural activity at the mesencephalic or diencephalic levels. Aims: The aim of the study was to study the brainstem auditory-evoked potentials (BAEP) in two meditation states based on consciousness, viz. dharana, and dhyana. Materials and Methods: Thirty subjects were selected, with ages ranging from 20 to 55 years (M=29.1; ±SD=6.5 years) who had a minimum of 6 months experience in meditating “OM”. Each subject was assessed in four sessions, i.e. two meditation and two control sessions. The two control sessions were: (i) ekagrata, i.e. single-topic lecture on meditation and (ii) cancalata, i.e. non-targeted thinking. The two meditation sessions were: (i) dharana, i.e. focusing on the symbol “OM” and (ii) dhyana, i.e. effortless single-thought state “OM”. All four sessions were recorded on four different days and consisted of three states, i.e. pre, during and post. Results: The present results showed that the wave V peak latency significantly increased in cancalata, ekagrata and dharana, but no change occurred during the dhyana session. Conclusions: These results suggested that information transmission along the auditory pathway is delayed during cancalata, ekagrata and dharana, but there is no change during dhyana. It may be said that auditory information transmission was delayed at the inferior collicular level as the wave V corresponds to the tectum. PMID:21170228

Kumar, Sanjay; Nagendra, HR; Naveen, KV; Manjunath, NK; Telles, Shirley

2010-01-01

4

Comparison of binaural auditory brainstem responses and the binaural dierence potential evoked by chirps and clicks  

E-print Network

auditory brainstem responses were recorded for clicks and chirps for levels from 10 to 60 dB nHL in steps and 40 dB nHL. Both the binaurally evoked potential and the binaural difference potential exhibit steeper growth functions for chirps than for clicks for levels up to 40 dB nHL. For higher stimulation levels

Oldenburg, Carl von Ossietzky, Universität

5

Brainstem and middle latency auditory evoked potentials in autism and developmental language disorder  

Microsoft Academic Search

Brainstem auditory evoked potentials (BAEP) and middle latency responses (MLR) were studied in 8 nonretarded subjects with infantile autism (mean age=23.3,SD=2.8), 8 subjects with receptive developmental language disorder (mean age=16.3,SD=1.4), and normal control subjects matched to each group for age, gender, and Performance IQ. Click stimuli were delivered monaurally to the left and the right ear and binaurally for both

Christian Grillon; Eric Courchesne; Natacha Akshoomoff

1989-01-01

6

[Clinical study of cortical and brainstem evoked potentials in head injury].  

PubMed

Three types of evoked potentials (EPs) auditory brainstem response (ABR), somatosensory evoked potential (SEP), and visual evoked potential (VEP) were recorded among 100 cases of head injuries within three days after the trauma had occurred. In order to assess these EPs, the normal wave patterns of 20 healthy subjects were used for comparison. For indices, wave I, III and V were used for ABR, N1, N2 and N3 for SEP, and N70, P100 and N125 for VEP. On this basis, five EP grades were constructed, from normal (grade I) to highly abnormal (grade V). Furthermore, an EP pattern classification was devised to integrate the respective EP grade. Namely, pattern A (PA), consisting of grade (G). I-III of the 3 types of EP; PB, composed of one type of EP or both ABR and VEP at G. IV-V; PC, consisting of both SEP and VEP at G. IV-V; PD, comprising both ABR and SEP at G. IV-V; and PE, covering all three types EPs at G. IV-V. In this EP pattern classification, PA signifies no severe damage, PB localized damage, PC severe cerebral damage, PD severe brainstem damage, PE severe diffuse damage. The significance was studied for an understanding of the pathological state, and for making a prognosis. The following conclusions were reached. 1. In severe head trauma, primary brainstem damage is very rare, and in cases where brainstem damage is shown, it is accompanied by extensive cerebral damage. To assess the pathological state of such primary cerebral damage EP in the acute stage is useful, and by performing further EP, successively, it becomes also possible to evaluate the secondary cerebral damage.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3226488

Nikaidou, Y; Shimomura, T; Hirabayashi, H; Utsumi, S; Kyoui, K; Miyamoto, S

1988-11-01

7

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. PMID:1469398

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

1992-01-01

8

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

PubMed

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

1982-12-01

9

Brainstem auditory evoked potentials in epileptics on different anti-epileptic drugs.  

PubMed

The effects of anti-epileptic drugs (AEDs) on brainstem auditory evoked potentials (BAEPs) were studied on 32 female patients of epilepsy and 10 age-matched normal healthy females (NS). The patients were divided into 6 groups, those not receiving medication (drug free, DF) and those receiving AEDs: Phenytoin (PHT), Carbamazepine (CBZ), Phenobarbital (PB), a combination of PHT and PB and a combination of CBZ and PB. DF epileptics had shortened were V absolute latency (AL) and I-V interpeak latency (IPL) as compared to NS. Phenytoin and CBZ monotherapy produced a prolongation of wave III AL (by PHT only), wave V AL, wave I-III IPL and I-V IPL, as compared to DF epileptics. Phenytoin monotherapy also prolonged wave III AL and I-III IPL, as compared to NS. When PB in the dosage of 30-60 mg/d was used in combination with PHT the above mentioned changes were not observed. These findings indicate altered neuronal conduction and/or synaptic transmission in epileptics. Anti-epileptic drugs in the dosages studied, with exception of PHT appear to lead towards "normalization" of BAEPs. PMID:8864768

Panjwani, U; Singh, S H; sel Vamurthy, W; Gupta, H L; Mukhopadhyay, S; Thakur, L

1996-01-01

10

Speech evoked auditory brainstem response in stuttering.  

PubMed

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

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

2014-01-01

11

Speech Evoked Auditory Brainstem Response in Stuttering  

PubMed Central

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

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

2014-01-01

12

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

Microsoft Academic Search

It is difficult to predict the onset of clinical symptoms due to Chiari II malformation. Brainstem auditory evoked potentials\\u000a (BAEPs) may be useful to select potential candidates for surgery. We studied 158 BAEPs in 134 asymptomatic children with meningomyelocele\\u000a (MMC) during the first year of life. Both wave latencies (WLs) and interpeak latencies (IPLs) in asymptomatic children with\\u000a MMC gradually

Motoharu Fujii; Tadanori Tomita; David G. McLone; John A. Grant; Cynthia V. Stack; Koreaki Mori

1997-01-01

13

[Auditory evoked potentials].  

PubMed

Auditory evoked potentials (AEPs) are an electrical manifestation of the brain response to an auditory stimulus. The waveform represents the passage of electrical activity provoked by auditory stimuli from the cochlea to cortex. The waves represented by I-VII are generated mainly in the brainstem. These waves are called the brain stem auditory evoked potentials (BAEPs) or the auditory brain stem response (ABR). The middle latency AEPs (MLAEP) are generated from the medial geniculate and primary auditory cortex. The long latency AEPs (LLAEP) are generated from the frontal cortex and association areas. The BAEPs appear to be an exquisitely sensitive monitor for pathological events during surgery. Anesthetics and mild hypothermia have minimum effect, if any, on the BAEPs. The BAEPs are useful during the microvascular decompression of the fifth or seventh cranial nerve, resection of acoustic neuroma and posterior fossa operations. Because the auditory pathway occupies a small area in the brainstem, combined use of other evoked potentials such as short latency sensory evoked potentials is recommended. The MLAEPs are most promising evoked responses for monitoring awareness or depth of anesthesia. When the concentration of anesthetics is increased, the amplitudes of the MLAEP's peaks are decreased and their latencies are elongated. Commercially developed A-line AEP monitor or aepEX can extract the AEPs waveform in a short period and automatically analyze the changes in the MLAEPs. These AEP based monitors may be superior to bispectral index (BIS) in detecting the transition from unconsciousness to consciousness. PMID:16541780

Morimoto, Yasuhiro; Sakabe, Takefumi

2006-03-01

14

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

PubMed

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

1996-12-01

15

Visual, long-latency auditory and brainstem auditory evoked potentials in migraine: relation to pattern size, stimulus intensity, sound and light discomfort thresholds and pre-attack state.  

PubMed

We aimed to estimate primary sensory evoked potential (EP) amplitude, amplitude-intensity functions and habituation in migraine patients compared with healthy control subjects and to investigate the possible relation to check size, sound and light discomfort thresholds, and the time to the next attack. Amplitudes of cortical visual evoked potentials (VEP, check size 8' and 33'), cortical long latency auditory evoked potential (AEP NIP1; 40, 55 and 70 dB SL tones) and brainstem auditory evoked potential (BAEP wave IV-V; 40, 55 and 65 dB SL clicks) were recorded and analysed in a blind and balanced design. The difference between the response to the first and the second half of the stimulus sequence was used as a measure of habituation. Twenty-one migraine patients (16 women and five men, mean age 39.3 years, six with aura, 15 without aura) and 22 sex- and age-matched healthy control subjects were studied (18 women and four men, mean age 39.5 years). Low sound discomfort threshold correlated significantly with low levels of BAEP wave IV-V amplitude habituation (r = -0.30, P = 0.05). VEP an AEP amplitudes, habituation, and amplitude-intensity function (ASF) slopes did not differ between groups when ANOVA main factors were considered. Control group VEP habituation was found for small check stimuli (P = 0.04), while potentiation was observed for medium sized checks (P = 0.02). The eight migraine patients who experienced headache within 24 h after the test tended to have increased BAEP wave IV-V ASF slopes (P = 0.08). This subgroup did also have a significant VEP habituation to small checks (P = 0.04). No correlation was found between different modalities. These results suggest that: (i) VEP habituation/potentiation state and brainstem activatio state may depend on the attack-interval cycle in migraine; (ii) VEP habituation/ potentiation may depend on spatial stimulus frequency; (iii) phonophobia (and possibly photophobia) may depend more on subcortical (brainstem) function than on cortical mechanisms; (iv) low cortical preactivation in migraine could not be confirmed; (v) EP habituation and ASF analysis may reflect sensory modality-specific, not generalized, central nervous system states in migraine and healthy control subjects. PMID:11167910

Sand, T; Vingen, J V

2000-11-01

16

On the combination of otometry with brainstem-evoked response audiometry.  

PubMed

Compound action potentials (AP) are measured in guinea pigs during stimulation with damped waves or with tone bursts. Results are compared in order to investigate whether damped waves are suitable stimuli for brainstem-evoked response audiometry. This investigation was done because a combination of brainstem-evoked response audiometry with otometry was recently proposed. Otometry is a hearing aid fitting method using damped waves as acoustic stimuli. PMID:7444322

Wit, H P; Nijdam, H F

1980-01-01

17

Auditory Brainstem Evoked Responses in Newborns with Down Syndrome  

ERIC Educational Resources Information Center

Auditory brainstem evoked responses (ABRs) were compared in 15 newborns with Down syndrome and 15 sex-, age-, and weight-matched control newborns. Participants had normal ABRs based upon values specific to 32- to 42-weeks postconceptional age. Although Wave III and Wave V component latencies and the Wave I-III interpeak latency (IPL) were shorter…

Kittler, Phyllis M.; Phan, Ha T. T.; Gardner, Judith M.; Miroshnichenko, Inna; Gordon, Anne; Karmel, Bernard Z.

2009-01-01

18

Speech evoked auditory brainstem responses: a new tool to study brainstem encoding of speech sounds.  

PubMed

The neural encoding of speech sound begins in the auditory nerve and travels to the auditory brainstem. Non speech stimuli such as click or tone bursts stimulus are used to check the auditory neural integrity routinely. Recently Speech evoked Auditory Brainstem measures (ABR) are being used as a tool to study the brainstem processing of Speech sounds. The aim of the study was to study the Speech evoked ABR to a consonant vowel (CV) stimulus. 30 subjects with normal hearing participated for the study. Speech evoked ABR were measured to a CV stimulus in all the participants. The speech stimulus used was a 40 ms synthesized/da/sound. The consonant and vowel portion was analysed separately. Speech evoked ABR was present in all the normal hearing subjects. The consonant portion of the stimulus elicited peak V in response waveform. Response to the vowel portion elicited a frequency following response (FFR). The FFR further showed a coding of the fundamental frequency (F0) and the first formant frequency (F1). The results of the present study throw light on the processing of speech in brainstem. The understanding of speech evoked ABR has other applications both in research as well as in clinical purposes. Such understanding is specially important if one is interested in studying the central auditory system function. PMID:22319700

Sinha, Sujeet Kumar; Basavaraj, Vijayalakshmi

2010-10-01

19

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. PMID:22396426

Allen, Paul D.; Ison, James R.

2012-01-01

20

Modeling auditory evoked brainstem responses to transient stimuli.  

PubMed

A quantitative model is presented that describes the formation of auditory brainstem responses (ABRs) to tone pulses, clicks, and rising chirps as a function of stimulation level. The model computes the convolution of the instantaneous discharge rates using the "humanized" nonlinear auditory-nerve model of Zilany and Bruce [J. Acoust. Soc. Am. 122, 402-417 (2007)] and an empirically derived unitary response function which is assumed to reflect contributions from different cell populations within the auditory brainstem, recorded at a given pair of electrodes on the scalp. It is shown that the model accounts for the decrease of tone-pulse evoked wave-V latency with frequency but underestimates the level dependency of the tone-pulse as well as click-evoked latency values. Furthermore, the model correctly predicts the nonlinear wave-V amplitude behavior in response to the chirp stimulation both as a function of chirp sweeping rate and level. Overall, the results support the hypothesis that the pattern of ABR generation is strongly affected by the nonlinear and dispersive processes in the cochlea. PMID:22559366

Rřnne, Filip Munch; Dau, Torsten; Harte, James; Elberling, Claus

2012-05-01

21

[Spasmodic torticollis, substantiating Manto syndrome, of possible toxic aethiology, with alterations of brainstem acoustic evoked potentials (BAEPs). Treatment with L-5-hydroxytryptophan. Follow up of 18 months, during which high degree resolution of symptoms and normalization of BAEPs took place].  

PubMed

A case of very severe spasmodic torticollis observed for 18 months is presented and discussed. Head was so rotated that permitted only backward seeing and compressed brachial plexus between scaleni muscles with sensory, motor and trophic troubles in the hand. A toxic aethiology from parathion is likely. Brainstem Acoustic Evoked Potentials (BAEPs) showed in the beginning abnormal responses, especially as refers to waves originating in the mesencephalon. Therapy with L-5-hydroxytryptophan subdued neurological symptoms; a parallel normalization of BAEPs recording was observed. The Authors propose to call this syndrome (spasmodic torticollis with thoracic outlet syndrome) after the mythical diviner Manto, which Dante Alighieri refers to in his "Divina Commedia" (Inferno, XX, 55 e segg.). PMID:6985243

Disertori, B; Ducati, A; Piazza, M

1982-01-01

22

SOMATOSENSORY EVOKED POTENTIALS  

EPA Science Inventory

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

23

Reference values of the brainstem auditory evoked response of methoxyflurane anesthetized and unanesthetized dogs  

Microsoft Academic Search

The brainstem auditory evoked response (BAER) was recorded from 7 unanesthetized and 27 methoxyflurane anesthetized dogs. A 0.1 msec, 70 dB stimulus delivered at 10 Hz evoked the expected seven wave BAER. Mean peak wave latencies and standard deviations were calculated. Differences were not found between neither right and left ears, nor male and female dogs. The anesthetized dogs had

L. J. Myers; Richard W. Redding; Sharon Wilson

1985-01-01

24

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

1980-01-01

25

Evoked potentials in the ICU.  

PubMed

The most informative neurophysiological techniques available in the neurosurgical intensive care unit are electroencephalograph and somatosensory evoked potentials. Such tools, which give an evaluation of cerebral function in comatose patients, support clinical evaluation and are complementary to neuroimaging. They serve both diagnostic/prognostic and monitoring purposes. While for the former, discontinuous monitoring is sufficient, for the latter, to obtain increased clinical impact, continuous monitoring is necessary. To perform and interpret these examinations in the neurosurgical intensive care unit, both the technician and the neurophysiologist need specific training in the intensive care field. There is sufficient evidence to show that somatosensory evoked potentials are the best single indicator of early prognosis in traumatic and hypoxic-ischaemic coma compared to the Glasgow Coma Score, computed tomography scan and electroencephalograph. Indeed, somatosensory evoked potentials should always be combined with clinical examination to determine the prognosis of coma. Despite widespread use of somatosensory evoked potentials and their prognostic utility in acute brain injury, few studies exist on continuous somatosensory evoked potential monitoring in the intensive care unit. We carried out a pilot study of continuous electroencephalograph-somatosensory evoked potential monitoring in the neurosurgical intensive care unit (traumatic brain injury and intracranial haemorrhage, Glasgow Coma Score <9, intracranial pressure monitoring). All patients stable from a clinical and computed tomography scan point of view showed no significant somatosensory evoked potential modifications, while in the case of clinical deterioration (23%), somatosensory evoked potentials always showed significant modifications. While somatosensory evoked potentials correlated with short-term outcome, intracranial pressure showed a poor correlation. We believe neurophysiological monitoring is an ideal complement to the other parameters monitored in the neurosurgical intensive care unit. Whereas intracranial pressure is simply a pressure index, electroencephalograph-somatosensory evoked potential monitoring reflects to what extent cerebral parenchyma still remains metabolically active during acute brain injury. PMID:18289442

Amantini, A; Amadori, A; Fossi, S

2008-01-01

26

The binaural click-evoked auditory brainstem response of the California sea lion (Zalophus californianus).  

PubMed

Auditory brainstem responses (ABRs) elicited by high-amplitude [100 dB re 20 ?Pa, peak-to-peak equivalent sound pressure level (peSPL)] aerial broadband clicks were collected from seven California sea lions in order to provide a basic description of short-latency auditory evoked potentials in this species. The waveform of the ABR was similar to that of other mammals, comprising seven positive and six negative characteristic waves. Variability in the amplitudes and latencies of waves was higher among subjects than the variability in within-subject repeated measurements. ABRs to progressively attenuated clicks were collected for three additional sea lions. Wave amplitudes decreased and latencies increased with decreasing stimulus level, with only the sixth positive wave visible near threshold (35-40 dB peSPL). Based on observations of wave latency as a function of stimulus amplitude, the sixth positive wave of the ABR is equivalent to the clinically important "wave V" identified in studies with humans. The current results provide information on the basic electrophysiology of the pinniped auditory system, including the processes that underlie brainstem auditory steady-state responses used to measure frequency-specific hearing sensitivity. PMID:23297929

Mulsow, Jason; Reichmuth, Colleen

2013-01-01

27

Eye movements and brainstem neuronal responses evoked by cerebellar and vestibular stimulation in chicks  

Microsoft Academic Search

The vestibulo-ocular reflex undergoes adaptive changes that require inputs from the cerebellar flocculus onto brainstem vestibular neurons. As a step toward developing an in vitro preparation in chicks for studying the synaptic basis of those changes, we have elucidated the organization of the pathways through which the flocculus influences vestibulo-ocular movements. Electrical stimulation of the vestibular ampulla evoked brief, contralaterally

Sascha Lac; Stephen G. Lisberger

1992-01-01

28

Speech-evoked brainstem frequency-following responses during verbal transformations due to word repetition  

Microsoft Academic Search

Speech-evoked brainstem frequency-following responses (FFRs) were recorded to repeated presentations of the same stimulus word. Word repetition results in illusory verbal transformations (VTs) in which word perceptions can differ markedly from the actual stimulus. Previous behavioral studies support an explanation of VTs based on changes in arousal or attention. Horizontal and vertical dipole FFRs were recorded to assess responses with

Gary C. Galbraith; Soham P. Jhaveri; Jeff Kuo

1997-01-01

29

DIFFERENTIAL IMPACT OF HYPOTHERMIA AND PENTOBARBITAL ON BRAINSTEM AUDITORY EVOKED RESPONSE  

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...

30

Brainstem Auditory Evoked Responses in Chronic Renal Failure and the Effect of Hemodialysis  

Microsoft Academic Search

Brainstem auditory evoked responses (BAER) were recorded in patients with chronic renal failure before commencement of chronic dialysis treatment, and in patients with end-stage renal failure on chronic hemodialysis for several years. Both groups of patients had delayed latencies of the third and fifth waves. The patients on hemodialysis revealed delayed latency of interpeak I-V as well. There was no

U. Gafter; Y. Shvili; J. Levi; Y. Talmi; Y. Zohar

1989-01-01

31

The binaural click-evoked auditory brainstem response of the California sea lion (Zalophus californianus)  

E-print Network

The binaural click-evoked auditory brainstem response of the California sea lion (Zalophus collected from seven California sea lions in order to provide a basic description of short-latency auditory to progressively attenuated clicks were collected for three additional sea lions. Wave amplitudes decreased

Reichmuth, Colleen

32

Test-retest consistency of speech-evoked auditory brainstem responses in typically-developing children.  

PubMed

The click-evoked auditory brainstem response (ABR) is widely used in clinical settings, partly due to its predictability and high test-retest consistency. More recently, the speech-evoked ABR has been used to evaluate subcortical processing of complex signals, allowing for the objective assessment of biological processes underlying auditory function and auditory processing deficits not revealed by responses to clicks. Test-retest reliability of some components of speech-evoked ABRs has been shown for adults and children over the course of months. However, a systematic study of the consistency of the speech-evoked brainstem response in school-age children has not been conducted. In the present study, speech-evoked ABRs were collected from 26 typically-developing children (ages 8-13) at two time points separated by one year. ABRs were collected for /da/ presented in quiet and in a 6-talker babble background noise. Test-retest consistency of response timing, spectral encoding, and signal-to-noise ratio was assessed. Response timing and spectral encoding were highly replicable over the course of one year. The consistency of response timing and spectral encoding found for the speech-evoked ABRs of typically-developing children suggests that the speech-evoked ABR may be a unique tool for research and clinical assessment of auditory function, particularly with respect to auditory-based communication skills. PMID:22197852

Hornickel, Jane; Knowles, Erica; Kraus, Nina

2012-02-01

33

Frequency specificity of chirp-evoked auditory brainstem responses  

NASA Astrophysics Data System (ADS)

This study examines the usefulness of the upward chirp stimulus developed by Dau et al. [J. Acoust. Soc. Am. 107, 1530-1540 (2000)] for retrieving frequency-specific information. The chirp was designed to produce simultaneous displacement maxima along the cochlear partition by compensating for frequency-dependent traveling-time differences. In the first experiment, auditory brainstem responses (ABR) elicited by the click and the broadband chirp were obtained in the presence of high-pass masking noise, with cutoff frequencies of 0.5, 1, 2, 4, and 8 kHz. Results revealed a larger wave-V amplitude for chirp than for click stimulation in all masking conditions. Wave-V amplitude for the chirp increased continuously with increasing high-pass cutoff frequency while it remains nearly constant for the click for cutoff frequencies greater than 1 kHz. The same two stimuli were tested in the presence of a notched-noise masker with one-octave wide spectral notches corresponding to the cutoff frequencies used in the first experiment. The recordings were compared with derived responses, calculated offline, from the high-pass masking conditions. No significant difference in response amplitude between click and chirp stimulation was found for the notched-noise responses as well as for the derived responses. In the second experiment, responses were obtained using narrow-band stimuli. A low-frequency chirp and a 250-Hz tone pulse with comparable duration and magnitude spectrum were used as stimuli. The narrow-band chirp elicited a larger response amplitude than the tone pulse at low and medium stimulation levels. Overall, the results of the present study further demonstrate the importance of considering peripheral processing for the formation of ABR. The chirp might be of particular interest for assessing low-frequency information.

Wegner, Oliver; Dau, Torsten

2002-03-01

34

Electrically-Evoked Frequency-Following Response (EFFR) in the Auditory Brainstem of Guinea Pigs  

PubMed Central

It is still a difficult clinical issue to decide whether a patient is a suitable candidate for a cochlear implant and to plan postoperative rehabilitation, especially for some special cases, such as auditory neuropathy. A partial solution to these problems is to preoperatively evaluate the functional integrity of the auditory neural pathways. For evaluating the strength of phase-locking of auditory neurons, which was not reflected in previous methods using electrically evoked auditory brainstem response (EABR), a new method for recording phase-locking related auditory responses to electrical stimulation, called the electrically evoked frequency-following response (EFFR), was developed and evaluated using guinea pigs. The main objective was to assess feasibility of the method by testing whether the recorded signals reflected auditory neural responses or artifacts. The results showed the following: 1) the recorded signals were evoked by neuron responses rather than by artifact; 2) responses evoked by periodic signals were significantly higher than those evoked by the white noise; 3) the latency of the responses fell in the expected range; 4) the responses decreased significantly after death of the guinea pigs; and 5) the responses decreased significantly when the animal was replaced by an electrical resistance. All of these results suggest the method was valid. Recording obtained using complex tones with a missing fundamental component and using pure tones with various frequencies were consistent with those obtained using acoustic stimulation in previous studies. PMID:25244253

Zhang, Ruxiang; Chen, Jing; Zhang, Daoxing; Wu, Xihong

2014-01-01

35

Vestibular Evoked Myogenic Potentials in Patients With Acoustic Neuromas  

Microsoft Academic Search

Background: To diagnose acoustic neuromas (ANs), the auditory brainstem response test and the caloric test have been used in addition to magnetic resonance imaging. The auditory brainstem response and the caloric tests mainly reflect functions of the auditory pathway, ie, the cochlear nerve and the superior vestibular nerve, respec- tively. Because the vestibular evoked myogenic poten- tial (VEMP) has been

Toshihisa Murofushi; Masaki Matsuzaki; Masahiro Mizuno

1998-01-01

36

Prognostic significance of the auditory brainstem evoked response in high-risk neonates.  

PubMed

The prognostic significance of the auditory brainstem evoked response (ABR) was examined in this prospective study of neonates at risk for neurodevelopmental sequelae. ABR testing was performed in the neonatal period (37 to 45 weeks conceptional age) and at two and/or six months corrected age. 34 high-risk newborns and 14 controls were followed to one year of age, when they received neurological and developmental assessments. Increased I to III and I to V interwave latencies predicted gross motor delay at one year, with a positive predictive power of 83 per cent and a specificity of 94.7 per cent. Increased brainstem conduction, dispersal of waves III to V and V/I amplitude ratio abnormalities predicted abnormal neurological findings at one year, with positive predictive values of 100, 100 and 80 per cent, respectively. A standard clinical examination of the newborn, performed on the at-risk and control infants at 40 weeks conceptional age, was not found to be strongly predictive of neurodevelopmental deficits at one year. PMID:3371571

Majnemer, A; Rosenblatt, B; Riley, P

1988-02-01

37

Cortical Evoked Potentials to an Auditory Illusion: Binaural Beats  

PubMed Central

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

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

2009-01-01

38

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

2005-01-01

39

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

PubMed

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

2014-06-01

40

MRI measurement of the canine auditory pathways and relationship with brainstem auditory evoked responses.  

PubMed

The objective of this study was to determine direct measurements of auditory pathways by magnetic resonance imaging (MRI) during the growth period of healthy Beagles, and to discover how canine brainstem auditory evoked response (BAER) latencies vary in relation to these MRI measurements. Eighty healthy Beagles were tested at eight, 16 and 52 weeks of age (stages 1, 2, 3, respectively) with BAER and brain MRI. The BAER interpeak latency (IPL) II-V and brain MRI neural generators of BAER waves II and V were identified. A linear distance was calculated in millimeters in order to determine the approximate length of auditory pathways. Sensory nerve conduction velocity (SNCV) of the auditory pathway between peak II and peak V was calculated for each group. A significant difference was observed between brain MRI distances among the three stages. Mean BAER IPL II-V were not significantly different between the three stages. The progressive growth of the skull and brain witnessed by the progressive increased distance of the MRI auditory pathways between peak II and peak V was not associated with a progressive maturation of the BAER IPL II-V. The SNCV of the auditory pathway between peak II and peak V was 6.14 m/sec for group 1; 6.76 m/sec for group 2; and 7.32 m/sec for group 3. PMID:18536850

Poma, R; Chambers, H; da Costa, R C; Konyer, N B; Nykamp, S; Dobson, H; Milgram, N W

2008-01-01

41

Sensorineural hearing loss with brainstem auditory evoked responses changes in homozygote and heterozygote sickle cell patients in Guadeloupe (France).  

PubMed

This prospective study involved 79 homozygote and heterozygote sickle cell anaemia patients (16 to 50 years old) and a control group of 40 people.All patients underwent ENT, audiological and brainstem auditory evoked responses (BSER) examinations in order to evaluate the incidence of sensorineural hearing loss (SNHL), to identify the changes at the level of the cochlear nerve and the central pathways, and to determine the most vulnerable group, in order to intervene with early prevention and rehabilitation for this condition.A hearing loss of greater than 20 dB at two or more frequencies was found in 36 (45.57 per cent) sickle cell patients (19 (47.22 per cent) HbSC patients and 17 (43.59 per cent) HbSS patients) and three (7.5 per cent) members of the control group. Homozygote and heterozygote patients, as well as both sexes, were equally affected. Bilateral hearing loss occurred in 19 (52.78 per cent) patients, unilateral right-sided hearing loss in five (13.89 per cent) patients and unilateral left-sided hearing loss in 12 (33.33 per cent) patients. Brainstem auditory evoked potential demonstrated a prolonged I-V (III-V) interpeak latency in 13 (25.35 per cent) sickle cell patients (11 men (eight with HbSS) and two women). The hearing loss in HbSS patients was neural in nature and of earlier onset; the hearing loss in HbSC patients was usually cochlear in nature and of later onset. Despite high medical standards and 100 per cent social security cover, the high incidence of SNHL in our sickle cell affected patients (the majority with the Benin haplotype) was probably due to their specific haematological profile and to the original geographical distribution of the disease in the tropics. Our results highlight the necessity for early and regular hearing assessment of sickle cell patients, including BSER examination, especially in male patients with SNHL. PMID:16762092

Jovanovic-Bateman, L; Hedreville, R

2006-08-01

42

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.

2002-05-01

43

[Significance of multimodality evoked potentials (MEPs) in severe head injuries].  

PubMed

Clinical significance of multimodality evoked potentials (MEPs) consisting of auditory evoked brainstem response (ABR), cortical somatosensory evoked potential (SEP) and visual evoked potential (VEP) was studied in 14 cases with severe head injuries. The cases in this series associated with cerebral contusion and/or intracranial mass lesions such as acute subdural, intracerebral and acute epidural hematomas and Glasgow Coma Scale (GCS) score was less than 8 in all instances. MEPs were recorded for 14 days after injury and evaluated by MEP grade modified from Greenberg, et al. Intracranial pressure (ICP) was monitored from the extradural space on main lesion side in all cases for 3 to 5 days. Transtentorial herniation on CT scan was also graded according to the status of subarachnoid cisterns around the tentorium. The outcome was assessed by Glasgow Outcome Scale at 3 months after injury and was classified into good, poor and dead. MEPs on admission showed mild to severe abnormalities determined by single or all modalities in all cases and they were fairly well correlated with GCS score on admission and initial ICP. In the cases with good outcome, initial MEPs showed mild to moderate abnormalities determined by single modality and improved within 3 days after injury. They returned to normal or remained at mild abnormality at 7 days. But abnormality on initial MEPs was more severe in the cases with poor outcome and they were deteriorated within 3 to 7 days when elevation of ICP above 25 mmHg was observed. MEPs remained at moderate abnormality even at 14 days after injury in these cases.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:4080080

Yuge, T; Shigemori, M; Tokutomi, T; Yamamoto, F; Kawasaki, K; Kawaba, T; Watanabe, M; Kuramoto, S

1985-10-01

44

Auditory evoked potentials in young patients with Down syndrome. Event-related potentials (P3) and histaminergic system  

Microsoft Academic Search

Subjects with Down syndrome exhibit various types of cognitive impairment. Besides abnormalities in a number of neurotransmitter systems (e.g. cholinergic), histaminergic deficits have recently been identified. Brainstem auditory evoked potentials (BAEPs) and auditory event-related potentials (ERPs), were recorded from 10 children (aged 11–20 years) with Down syndrome and from 10 age- and sex-matched healthy control subjects. In Down subjects, BAEPs

Rainer Seidl; Erwin Hauser; Günther Bernert; Manfred Marx; Michael Freilinger; Gert Lubec

1997-01-01

45

Laser evoked potentials in Carpal Tunnel Syndrome  

Microsoft Academic Search

ObjectivesThe aim of this study was to evaluate the function of A? fibers at the hand level in patients with clinical symptoms of Carpal Tunnel Syndrome (CTS) using CO2 laser evoked potentials (LEPs), in light of the intensity and distribution of sensory symptoms and pain.

Marina de Tommaso; Giuseppe Libro; Olimpia Difruscolo; Michele Sardaro; Claudia Serpino; Rita Calabrese; Eleonora Vecchio; Paolo Livrea

2009-01-01

46

Visual evoked potentials, auditory evoked potentials and EEG in shunted hydrocephalic children.  

PubMed

Visual evoked potentials (VEP) and auditory evoked potentials (AEP) were studied together with the EEG, in 15 hydrocephalic children who had been shunted previously, and in a control group of 10 normal children. From the control group normal VEP's, AEP's and EEG's were obtained. In all 15 hydrocephalic children the EEG was abnormal. AEP's were normal in 9 and abnormal in 6 cases. VEP's were normal in 7 and abnormal in 8 cases. Only 4 patients showed both abnormal VEP's and AEP's. No relation could be demonstrated between the severity of EEG disturbances and evoked response abnormalities. PMID:7254482

de Vlieger, M; Sadikoglu, S; van Eijndhoven, J H; Ataç, M S

1981-02-01

47

Startle evoked movement is delayed in older adults: implications for brainstem processing in the elderly  

PubMed Central

Abstract Little attention has been given to how age affects the neural processing of movement within the brainstem. Since the brainstem plays a critical role in motor control throughout the whole body, having a clear understanding of deficits in brainstem function could provide important insights into movement deficits in older adults. A unique property of the startle reflex is its ability to involuntarily elicit planned movements, a phenomenon referred to as startReact. The noninvasive startReact response has previously been used to probe both brainstem utilization and motor planning. Our objective was to evaluate deficits in startReact hand extension movements in older adults. We hypothesized that startReact hand extension will be intact but delayed. Electromyography was recorded from the sternocleidomastoid (SCM) muscle to detect startle and the extensor digitorum communis (EDC) to quantify movement onset in both young (24 ± 1) and older adults (70 ± 11). Subjects were exposed to a startling loud sound when prepared to extend their hand. Trials were split into those where a startle did (SCM+) and did not (SCM?) occur. We found that startReact was intact but delayed in older adults. SCM+ onset latencies were faster than SCM? trials in both the populations, however, SCM+ onset latencies were slower in older adults compared to young (? = 8 msec). We conclude that the observed age?related delay in the startReact response most likely arises from central processing delays within the brainstem. PMID:24907294

Tresch, Ursina A.; Perreault, Eric J.; Honeycutt, Claire F.

2014-01-01

48

[Clinical study of time-shift evoked potentials].  

PubMed

Changing the interaural time difference (ITD) of continuous band noise applied to both ears causes a shift in the perceived lateralization of the noise and evokes the special potentials called "time-shift evoked potentials (TPEPs)". These potentials consist of a positive-negative-positive complex, like a slow vertical response (SVR). Each peak latency of this potential, however, was about 20 msec longer than in the SVR. Testing of 45 volunteers with normal hearing revealed that the feature of this response matched the hearing function test results of detecting lateral position of a sound image. Therefore it could be useful as an objective testing for the hearing function of sound latelization. The following were established as the conditions for use, in clinical practice: time difference between ears: 0.7 msec; sound intensity: 30 dB SL at 500-Hz band noise; stimulus interval: 3.0 sec.; and potential recording from Cz on the scalp. This response was tested in 29 cases of hearing disorders (14 cases of inner ear deafness, 2 cases of tinnitus without deafness, 6 cases of peripheral vertigo, 5 cases of intracranial disease, 1 case of functional hearing loss, 1 case of head trauma), and the results were compared with those of the directional hearing test, auditory brainstem response (ABR), and SVR, by using the chi-square test. The results of the directional hearing test and ABR were shown to be correlated with this ERP, and SVR was shown to be independent of it. Thus, it was concluded that this potential is useful as a clinical test. The significance of the conclusions is explained on the basis of Berjeik's theory. PMID:8822255

Iizuka, N

1996-01-01

49

The mouse visually evoked potential : neural correlates and functional applications  

E-print Network

The visually evoked potential (VEP) is a local field potential (LFP) evoked in visual cortex in response to visual stimuli. Unlike extracellular single unit recordings, which allow us to probe the function of single spiking ...

Muhammad, Rahmat

2009-01-01

50

Visual evoked potential responses in pregnant women.  

PubMed

Sensory functions and their electrophysiological correlates have not been adequately documented during pregnancy. The present study reports visual evoked potential responses to pattern reversal (VEP-P) in ten third trimester pregnant women and changes in latency of NPN complex when compared with these responses in the non pregnant state. Visual evoked potentials were recorded from O1-A1 and O2-A2 scalp areas, using Ag/Agcl disc electrodes to transient pattern of black and white checkerboard with 32' size and reversal rate 1Hz. Two trials of VEP-P responses to 256 transient pattern stimuli given to each eye, were analysed and averaged by the computer of visual evoked potential recorder (MEB 5200 Nihon Kohden Japan). The latencies of various positive and negative waves, along with P1 amplitude, obtained in pregnant women, were compared with those obtained in ten non-pregnant women. The latencies of initial NPN complex (N1P1 & N2) were significantly reduced in pregnant women, indicating that pregnancy facilitates conduction process in the optic pathways. PMID:1812102

Tandon, O P; Bhatia, S

1991-10-01

51

Speech-evoked auditory brainstem responses reflect familial and cognitive influences  

E-print Network

brainstem response to speech is linked to language skill, reading ability, cognitive skills, and speech-in-noise perception; however, the impact of shared genetic and environmental factors on the response has not been matched on age, sex, IQ, and reading ability to one of the siblings (Reading-Matched), and (3) 22 pairs

Kraus, Nina

52

Application of Evoked Potential in Acute Stroke in Rats  

Microsoft Academic Search

The aim of this paper is to study the characteristic of latency of evoked potential and monitoring brain function following acute ischemic stroke in rats. The model of acute ischemic stroke in rats was made by middle cerebral artery occlusion (MCAO). All animals of ischemic stroke were detected latency of somatosensory evoked potential (SEP) and motor evoked potential (MEP) after

Yang Shao

2009-01-01

53

Measurement of the somatosensory magnetic evoked potential  

E-print Network

1983 Major Subject: BIOENGINEERING MEASUREMENT OP THE SOMATOSENSORY MAGNETIC EVOKED POTENTIAL A Thesis BENJAMIN LEWIS PASHKOPP Approved as to style and content by: Charles S. ssard, B. E. (Chairman) William A. H , B. E. (M ) /P Rodger J.... 1 G~t, N 3 I: IIQQ' -8 1 3, pp. 189-195, 1950. 39 VITA Benjamin Lewis Pashkoff received his B. S. in Bioengineering from Texas AAM University in May of 1982. He has an employment history that includes work with the Texas Heart Institute, Texas...

Pashkoff, Benjamin Lewis

2012-06-07

54

Visual evoked potentials in diabetic patients.  

PubMed

Visual evoked potentials (VEPs) were assessed in 50 adult type I (insulin-dependent) and 19 type II (noninsulin-dependent) diabetes mellitus patients and in 54 controls. P100 wave latency was significantly longer in diabetic patients (P less than .001). Twenty-eight percent of diabetic patients had P100 wave latencies above the normal range. There was no correlation between P100 latency and type or duration of diabetes mellitus, quality of metabolic control, or presence of degenerative complications. The significance of VEP abnormalities in diabetes mellitus remains speculative. PMID:2702915

Algan, M; Ziegler, O; Gehin, P; Got, I; Raspiller, A; Weber, M; Genton, P; Saudax, E; Drouin, P

1989-03-01

55

Spectral and synchrony differences in auditory brainstem responses evoked by chirps of varying durations.  

PubMed

The chirp-evoked ABR has been termed a more synchronous response, referring to the fact that rising-frequency chirp stimuli theoretically compensate for temporal dispersions down the basilar membrane. This compensation is made possible by delaying the higher frequency content of the stimulus until the lower frequency traveling waves are closer to the cochlea apex. However, it is not yet clear how sensitive this temporal compensation is to variation in the delay interval. This study analyzed chirp- and click-evoked ABRs at low intensity, using a variety of tools in the time, frequency, and phase domains, to measure synchrony in the response. Additionally, this study also examined the relationship between chirp sweep rate and response synchrony by varying the delay between high- and low-frequency portions of chirp stimuli. The results suggest that the chirp-evoked ABRs in this study exhibited more synchrony than the click-evoked ABRs and that slight gender-based differences exist in the synchrony of chirp-evoked ABRs. The study concludes that a tailoring of chirp parameters to gender may be beneficial in pathologies that severely affect neural synchrony, but that such a customization may not be necessary in routine clinical applications. PMID:20968361

Petoe, Matthew A; Bradley, Andrew P; Wilson, Wayne J

2010-10-01

56

Evoked potentials in severe head injury.  

PubMed

Provided herein is a summary of findings by the authors and other investigators regarding the application of evoked potential studies to the assessment of neurologic function in severely head-injured patients in the acute and subacute stages postinjury. Multimodality Evoked Potentials (MEP's) are reportedly useful in three primary areas: 1) diagnosis; 2) prognosis; and 3) monitoring recovery. In diagnosis, the abnormalities in MEP's can be associated specifically with focal sensory/motor deficits such as hemiparesis and, generally, with the severity and extent of brain dysfunction. MEP abnormalities that are severe reflect irreversible damage while the mild abnormalities point to transient, reversible CNS dysfunction. Definition of the severity and extent of brain dysfunction by MEP's allows an accurate prediction of outcome, or the potential for recovery. Their accuracy is superior to many commonly used indices and MEP results add strength to clinical indicators of prognosis. Changes in MEP results obtained within a patient over time can be used to trace recovery and assess, for an individual, the functional consequences of secondary neurologic insult or medical complication. The authors conclude that MEP studies may serve a useful function as noninvasive indices of neurologic function in the management of severely head-injured patients. PMID:6694227

Newlon, P G; Greenberg, R P

1984-01-01

57

SURFACE DISTRIBUTION OF FLASH-EVOKED AND PATTERN REVERSAL-EVOKED POTENTIALS IN HOODED RATS  

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...

58

Absence of both auditory evoked potentials and auditory percepts dependent on timing cues.  

PubMed

An 11-yr-old girl had an absence of sensory components of auditory evoked potentials (brainstem, middle and long-latency) to click and tone burst stimuli that she could clearly hear. Psychoacoustic tests revealed a marked impairment of those auditory perceptions dependent on temporal cues, that is, lateralization of binaural clicks, change of binaural masked threshold with changes in signal phase, binaural beats, detection of paired monaural clicks, monaural detection of a silent gap in a sound, and monaural threshold elevation for short duration tones. In contrast, auditory functions reflecting intensity or frequency discriminations (difference limens) were only minimally impaired. Pure tone audiometry showed a moderate (50 dB) bilateral hearing loss with a disproportionate severe loss of word intelligibility. Those auditory evoked potentials that were preserved included (1) cochlear microphonics reflecting hair cell activity; (2) cortical sustained potentials reflecting processing of slowly changing signals; and (3) long-latency cognitive components (P300, processing negativity) reflecting endogenous auditory cognitive processes. Both the evoked potential and perceptual deficits are attributed to changes in temporal encoding of acoustic signals perhaps occurring at the synapse between hair cell and eighth nerve dendrites. The results from this patient are discussed in relation to previously published cases with absent auditory evoked potentials and preserved hearing. PMID:2065245

Starr, A; McPherson, D; Patterson, J; Don, M; Luxford, W; Shannon, R; Sininger, Y; Tonakawa, L; Waring, M

1991-06-01

59

Pattern electroretinogram, visual evoked potential and psychophysical functions in maculopathy  

Microsoft Academic Search

To compare pattern electroretinograms and visual evoked potentials with psychophysical examinations, such as visual acuity, static (automated) perimetry and color vision in unilateral maculopathies of various origins, 20 patients with unilateral retinal diseases within the macula and the posterior pole were tested. Pattern electroretinography, visual evoked potential testing and static perimetry (Octopus program M1) were performed with three different test

Armin Junghardt; Hannes Wildberger; Béla Török

1995-01-01

60

Auditory Evoked Potentials and Impairments to Psychomotor Activity Evoked by Falling Asleep  

Microsoft Academic Search

Sounds provide the most suitable stimuli for studies of information processes occurring in the brain during falling asleep\\u000a and at different stages of sleep. The widely used analysis of evoked potentials averaged for groups of subjects has a number\\u000a of disadvantages associated with their individual variability. Thus, in the present study, measures of the individual components\\u000a of auditory evoked potentials

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

2010-01-01

61

Finding physiological responses in vestibular evoked potentials.  

PubMed

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

2011-01-01

62

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

2005-04-01

63

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. PMID:24626949

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

2014-01-01

64

Vestibular Evoked Myogenic Potentials : physiology, variability, and statistical characteristics  

E-print Network

Vestibular Evoked Myogenic Potentials (VEMPs) are electrical signals recorded from the skin overlying skeletal muscles of the head and neck in response to high-intensity acoustic stimuli. VEMPs have been observed in stimulus ...

Prakash, Srinivasamurthy Ravi

2009-01-01

65

KETAMINE ALTERS RAT FLASH EVOKED POTENTIALS (JOURNAL VERSION)  

EPA Science Inventory

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

66

Interaction of cortical evoked potentials in the rat  

PubMed Central

1. Unitary and mass potentials were recorded with glass micropipettes at different depths in and around the primary somatosensory area of the cortex in rats anaesthetized with urethane; in addition, surface mass potentials were recorded with chlorided silver ball electrodes. Potentials were evoked by stimuli to the contralateral forepaw and the contralateral cortex. Observations were confined to potentials evoked within 20 msec of stimulation. 2. If forepaw stimuli were applied at times when the cortex was not showing spontaneous activity, one component of the evoked response was a widespread depth negativity. This was accompanied by a smaller surface positivity which had the same time course. It could be recorded over the same area of cortex. Unitary activity was found with the same latent period and spatial distribution as the depth negativity. These components of the evoked mass and unitary responses to forepaw stimulation were absent if times of spontaneous cortical activity were chosen for delivering the stimuli. 3. Contralateral cortical stimuli evoked mass activity similar to the component of the mass response to forepaw stimulation described in 2. Stimuli given simultaneously to the two sites elicited less unitary activity than the sum of the unitary activity evoked by the two stimuli separately. The mass activity exhibited the interactions which would be expected on the hypothesis that it is generated by the unitary activity. The time course of the interaction is described. 4. The interaction was confined to the components of the evoked potentials which were only present if stimuli were applied when the cortex was quiescent. Stimuli applied when the cortex was active evoked mass and unitary potentials which showed no interaction. PMID:5499536

Holmes, O.; Short, A. D.

1970-01-01

67

CHRONIC DIETARY EXPOSURE WITH INTERMITTENT SPIKE DOSES OF CHLORPYRIFOS FAILS TO ALTER BRAINSTEM AUDITORY EVOKED RESPONSE (BAERS) IN RATS.  

EPA Science Inventory

Human exposure to pesticides is often characterized by chronic low level exposure with intermittent spiked higher exposures. Cholinergic transmission is involved in auditory structures in the periphery and the brainstem and is altered following chlorpyrifos exposure. This study e...

68

The clinical application of potentials evoked from the peripheral auditory system.  

PubMed

The auditory nerve is the obligatory pathway between the cochlea and the central nervous system. As the fibers of the mammalian auditory nerve share with each other many response properties when stimulated electrically (Kiang, 1965), it is reasonable to assume that the summed, or gross, electrical response of a fiber ensemble can provide researchers with meaningful information about nerve function. This chapter describes the gross responses of the auditory nerve that can be evoked by stimuli delivered by one or more electrodes implanted within the cochlea. Two manifestations of this potential--the electrically evoked compound action potential (ECAP) and the electrically evoked auditory brainstem response (EABR)--are introduced and compared. Some implant devices include systems that allow ECAPs to be routinely recorded from electrodes within the cochlea in clinical settings. While such systems have increased the popularity of the ECAP, unique advantages of the EABR are noted. Both potentials have assisted the clinical management of implant recipients and increase our understanding of how the human auditory system responds to electrical stimulation. The goals of this chapter are to review response characteristics of the whole-nerve response, the extent to which they provide information about underlying auditory nerve fiber activity, and limitations to their interpretation. This report will focus on describing and reviewing data collected from various clinical studies and interpreting these results on the basis of theoretical considerations and pertinent results from animal studies. Future research directions, which will likely involve the integration of various dimensions of the electrically evoked response that have been studied in isolation, are also suggested. PMID:18515023

Miller, Charles A; Brown, Carolyn J; Abbas, Paul J; Chi, Siu-Ling

2008-08-01

69

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. PMID:23372981

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

2012-01-01

70

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.

2003-05-01

71

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

PubMed

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

2010-01-01

72

The polarity histogram in relation to the average evoked potential.  

PubMed

It is shown analytically that the polarity histogram (PH) and the average evoked potential (AEP) are linearly related under certain conditions. The relative merits of the two approaches are compared both analytically and by statistical simulation. In general, the PH is a biased estimator of the evoked potential and is less efficient than the AEP, which is unbiased. The PH is more robust against artifact, but this advantage vanishes when conventional artifact rejection is used. The detection of an EP using the PH is problematic. The polarity histogram offers little advantage over signal averaging under typical clinical recording conditions. PMID:6186470

Hyde, M L; Doyle, D J

1983-03-01

73

[Clinical application of pain-related evoked potentials].  

PubMed

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

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

2012-02-01

74

EVOKED POTENTIALS, PHYSIOLOGICAL METHODS WITH HUMAN APPLICATIONS  

EPA Science Inventory

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

75

Surgical management of brain-stem cavernomas  

Microsoft Academic Search

We present a series of seven patients who were operated on for symptomatic brain-stem cavernomas. The following approaches were used: medial suboccipital (N = 4), lateral suboccipital (N = 1), subtemporal-transtentorial (N = 1), and frontal transcortical-transventricular-subchorioidaltrans velum interpositum (N = 1). Intraoperative motor (N = 4) and somatosensory (N = 1) evoked potential monitoring revealed temporary changes in 3

Ulrich Pechstein; Josef Zentner; Dirk Van Roost; Johannes Schramm

1997-01-01

76

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

PubMed

Sounds provide the most suitable stimuli for studies of information processes occurring in the brain during falling asleep and at different stages of sleep. The widely used analysis of evoked potentials averaged for groups of subjects has a number of disadvantages associated with their individual variability. Thus, in the present study, measures of the individual components of auditory evoked potentials were determined and selectively summed for individual subjects, with subsequent analysis by group. The aim of the present work was to identify measures of auditory evoked potentials providing quantitative assessment of the dynamics of the brain's functional state during the appearance of errors in activity associated with decreases in the level of waking and falling asleep. A monotonous psychomotor test was performed in the lying position with the eyes closed; this consisted of two alternating parts: the first was counting auditory stimuli from 1 to 10 with simultaneous pressing of a button, and the second was counting stimuli from 1 to 5 silently without pressing the button, and so on. Computer-generated sound stimuli (duration 50 msec, envelope filling frequency 1000 Hz, intensity 60 dB) were presented binaurally with interstimulus intervals of 2.4-2.7 sec. A total of 41 subjects took part (both genders, mean age 25 years), of which only 23 fell asleep; data for 14 subjects with sufficient episodes of falling asleep were analyzed. Comparison of measures of auditory evoked potentials (the latencies and amplitudes of the N1, P2, N2, and P3 components) during correct and erroneous psychomotor test trials showed that decreases in the level of consciousness elicited significant increases in the amplitudes of the components of the vertex N1-P2-N2 complex in series without button pressing. The greatest changes in auditory evoked potentials in both series were seen in the N2 component, with latency 330-360 msec, which has a common origin with the EEG theta rhythm and is characteristic of the first stage of sleep. PMID:20339938

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

2010-05-01

77

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.

1975-01-01

78

COMPARABILITY OF RAT AND HUMAN VISUAL EVOKED POTENTIALS  

EPA Science Inventory

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

79

ONTOGENY OF FLASH-EVOKED POTENTIALS IN UNANESTHETIZED RATS  

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...

80

Aging affects transcranial magnetic modulation of hippocampal evoked potentials  

E-print Network

Elsevier Science Inc. All rights reserved. Keywords: Transcranial magnetic stimulation; aging rats; dentate. Transcranial magnetic stimulation (TMS) is a new non- invasive, fairly safe method for stimulation of the brainAging affects transcranial magnetic modulation of hippocampal evoked potentials Y. Levkovitz, M

Segal, Menahem

81

Effect of musical modelling on late auditory evoked potentials  

Microsoft Academic Search

Late auditory evoked potentials were recorded in four subjects during musical tasks. A PDP 12 computer synchronized stimuli, which were produced by an integrated circuit, and recording with the help of a quartz time basis. The content of each experiment was different modelling of an ambiguous identical acoustic stimulus. In experiment 1, subjects had to model a 6-note melody according

Werner Paulus; Calwer Strasse

1988-01-01

82

PATTERN REVERSAL VISUAL EVOKED POTENTIALS IN AWAKE RATS  

EPA Science Inventory

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

83

Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users  

ERIC Educational Resources Information Center

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…

Munivrana, Boska; Mildner, Vesna

2013-01-01

84

Visual evoked potential in young adults: a normative study.  

PubMed

It is important to acquire adequate normative data of visual evoked potential before using it as a diagnostic tool. A study using visual evoked potential with pattern (VEP-P) was conducted in Twenty male and seven female young healthy subjects of 17-35 years age. Ag/Agcl electrodes anchored on scalp with collodion at O1-A1, O2-A2 (10-20 system), with transition skin to electrode impedence kept at less than 5 K ohms were connected to MEB 5200 Evoked potential Recorder (Nihon Kohden, Japan). The evoked responses to 256 visual stimuli were recorded using transient pattern reversal (checker size 32'), frequency 1/sec and contrast between black and white checks 67%. The responses were averaged by the computer and absolute peak latency values for P100 alongwith other positive and negative waves worked out. P100 latency of 95.37 +/- 6.85, amp. 6.4 +/- 2.38 for males and 91.07 +/- 49 msec, amp. 6.88 +/- 2.79 microv for females are being reported. The P100 latency values of present study are similar to those reported in age and sex matched subjects of the western world, indicating that there are no ethnic variations in P100 of VEP. PMID:2620968

Tandon, O P; Sharma, K N

1989-01-01

85

Estimation of evoked potentials using total least squares Prony technique  

Microsoft Academic Search

The authros investigate the applicability of Prony modelling to the estiamtion of evoked potentials. Four types of total least\\u000a squares (TLS) model are considered and their optimal parameters are defined based on ten visual averaged EPs. Simulations\\u000a with various signal and noise characteristics show that the TLS-Prony estimation is superior to averaging for two of the models,\\u000a namely the unconstrained

T. Akkin; S. Saliu

1998-01-01

86

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

2009-01-01

87

Steady-state visual evoked potentials to computer monitor flicker  

Microsoft Academic Search

In the present study, steady-state visual evoked potentials (S-VEP) in response to amplitude-modulated light from a computer monitor (colour sVGA, 15-inch tube) have been examined. S-VEPs to computer monitors with different refresh rates (60 Hz or 72 Hz) and screen brightness (65 cd\\/m2 or 6 cd\\/m2) were recorded in 13 subjects with normal or corrected-to-normal vision. EEG samples were amplified,

Eugene Lyskov; Valery Ponomarev; Monica Sandström; Kjell Hansson Mild; Sviatoslav Medvedev

1998-01-01

88

[Two patients with congenital insensitivity to pain with anhidrosis showing marked prolongation of central conduction time in short latency somatosensory evoked potential].  

PubMed

We examined the evoked potentials in 2 patients, a 6-month-old girl and a 3-year-old boy, with congenital insensitivity to pain with anhidrosis (CIPA). While auditory brainstem response (ABR) in both patients showed normal latencies, flash visual evoked potential (FVEP) revealed delayed latency of wave IV (P100), and short latency somatosensory evoked potential (SSEP) demonstrated marked prolongation of the central conduction time (CCT; N13-N20 interval). The boy had West syndrome and his prolonged CCT might have been influenced by abnormal cortical activities. The girl did not have epilepsy and the abnormalities of her F-VEP and SSEP might have been caused by the developmental deficit of the central nervous system associated with the pathogenesis of CIPA. PMID:19928545

Tanaka, Ryuta; Sugai, Kenji; Fujikawa, Yoshinao; Komaki, Hirofumi; Nakagawa, Eiji; Saito, Yoshiaki; Ohto, Tatsuyuki; Hashimoto, Toshiaki; Sasaki, Masayuki

2009-11-01

89

Effects of vigabatrin on evoked potentials in dogs  

PubMed Central

1 The purpose of this study was to evaluate possible changes in brain morphology and evoked potentials associated with daily administration of 300 mg kg-1 vigabatrin in dogs. 2 Somatosensory evoked potentials (SEP) and auditory evoked potentials (AEP) were recorded at baseline and weekly for 12 weeks of treatment and every 2 weeks for 17 weeks of recovery. Morphology was assessed immediately after treatment for two treated dogs and after recovery for the remaining five treated and two control dogs. 3 Vigabatrin produced a significant slowing of the central transmission measure of the SEP with no alteration in the AEP. Vigabatrin was associated with microvacuolation in select regions of the brain including the fornix, septum, optic tract, hypothalamus, thalamus and cortex. In addition, some microglial proliferation was noted. 4 Changes in SEP and the microvacuolation fully recovered after 17 weeks of treatment. 5 The study confirms vigabatrin-induced microvacuolation in the dog and suggests these changes are associated with functional slowing of conduction in the somatosensory pathways. PMID:2757910

Arezzo, J. C.; Schroeder, C. E.; Litwak, M. S.; Steward, D. L.

1989-01-01

90

Improved processing of the steady-state evoked potential.  

PubMed

Two related procedures for estimating the parameters of steady-state evoked potentials (SSEPs) are introduced. The first procedure involves an initial stage of digital bandpass filtering followed by a Discrete Fourier Transform analysis. In the second method, a high resolution method based on parametric modelling is applied to the filtered data. The digital pre-filter consists of a non-phase shifting Chebychev bandpass filter. The parametric modelling method considers the evoked-response-plus-noise distribution to consist of a set of exponentially damped sinusoids. The frequency, amplitude, phase and damping factors of these components are estimated by calculating the mean of the forward and backward prediction filters and linear regression. We compared the signal-to-noise ratio (SNR) of the new procedures to the conventional Discrete Fourier Transform method for Monte Carlo simulations utilizing known sinusoids buried in white noise, known sinusoids buried in human EEG noise and for a sample of visual evoked potential data. Both of the new methods produce substantially more accurate and less variable estimates of test sinusoid amplitude. For VEP recording, the EEG background noise level is reduced by 5-6 dB over that obtained with the DFT. The new methods also provide approximately 5 dB better SNR than the DFT for detection of sinusoids based on the Rayleigh statistic. The parametric modelling approach is particularly suited for the analysis of very short data records including cycle-by-cycle analysis of the SSEP. PMID:7688287

Tang, Y; Norcia, A M

1993-01-01

91

Transient evoked otoacoustic emissions and vestibular evoked myogenic potentials in cigarette and water pipe smokers.  

PubMed

This study compared the amplitude of transient evoked otoacoustic emissions (TEOAEs) and latencies of vestibular evoked myogenic potentials (VEMPs) among non-smokers, cigarette smokers, water pipe smokers, mixed smokers and ex-smokers. A total of 50 non-smokers, 28 water pipe smokers, 34 pure cigarette smokers, 28 mixed cigarette-water pipe smokers, and 21 ex-smokers were evaluated in this study. Their age ranged from 20 to 40 years. All had normal hearing sensitivity and normal middle ear functions. TEOAEs amplitude and VEMPs were measured for all participants. Results of this study showed that smoking had deleterious effects on the hair cells in the labyrinth. Damage to the outer hair cells was evidenced by the reduced amplitude of the TEOAEs in smokers and ex-smokers when compared with control group. Harm to the saccular hair cells is detected by the increased latency of the VEMPs. Results also suggested that cessation of smoking could not change the profile of TEOAEs or VEMPs. Our results suggested that smoking could have irreversible hazardous effects on the labyrinthine hair cell functions. These effects could be attributed to the impact of nicotine on the microvascular dynamics. PMID:24121784

Mustafa, Mohamed Wael Mohamed

2014-10-01

92

Evoked potentials to electrical stimulation of the facial nerve in the carp tectum mesencephali  

Microsoft Academic Search

Tectal evoked potentials to stimulation of the facial nerve, containing afferent fibers of nonolfactory chemoreception, in the carp are positive evoked potentials with a latent period of 5 to 25 msec which show no phase shift as the microelectrode is advanced to a depth of 600 µ. Depending on the amplitude and latency of evoked potentials seven active zones differing

N. E. Vasilevskaya; L. N. Stankevich

1976-01-01

93

CHLORDIMEFORM PRODUCES CONTRAST-DEPENDENT CHANGES IN VISUAL EVOKED POTENTIALS OF HOODED RATS  

EPA Science Inventory

Acute exposure to the insecticide/acaricide chlordimeform (CDM) produces large, selective and transient changes in visual evoked potentials of rats. Experiments were conducted investigating the influence of physical characteristics of the evoking stimuli on the CDM effect. Adult ...

94

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. PMID:23316155

Veniero, Domenica; Bortoletto, Marta; Miniussi, Carlo

2013-01-01

95

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.

1996-01-01

96

The clinical application of neurogenic motor evoked potentials to monitor spinal cord function during surgery.  

PubMed

The purpose of this study was to report results from 300 cases (177 children, 123 adults) administered somatosensory and neurogenic motor evoked potentials during surgery. Of these 300 cases, there were 16 cases of spinal fractures, 16 neurosurgical cases, 28 vascular cases, and 240 cases of elective posterior spinal deformity requiring instrumentation. Results indicated that somatosensory evoked potentials, especially cortical components, demonstrated greater variability than neurogenic motor evoked potentials. Variability was attributed to anesthesia and unknown factors. Neurogenic motor evoked potentials proved to be a more valid indicator of postoperative motor status than somatosensory evoked potentials. Based on their anatomic substrates and results from this study, it was recommended that somatosensory evoked potentials and neurogenic motor evoked potentials be used to monitor spinal cord function during surgery that would place that structure at risk. PMID:1785092

Owen, J H; Bridwell, K H; Grubb, R; Jenny, A; Allen, B; Padberg, A M; Shimon, S M

1991-08-01

97

Estimation of evoked potentials using total least squares prony technique.  

PubMed

The authors investigate the applicability of Prony modelling to the estimation of evoked potentials. Four types of total least squares (TLS) model are considered and their optimal parameters are defined based on ten visual averaged EPs. Simulations with various signal and noise characteristics show that the TLS-Prony estimation is superior to averaging for two of the models, namely the unconstrained and the stable models. Application of the TLS-Prony estimator as a post-processor to moderate averaging allows a reduction in the number of responses averaged, or equivalently of recording time, by a factor of two. PMID:10367435

Akkin, T; Saliu, S

1998-09-01

98

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

99

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

PubMed

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

2012-07-01

100

Auditory and somatosensory evoked potentials in brain-dead patients.  

PubMed

The short latency evoked potentials, allowing to assess the brain stem's function, can supply useful information in the diagnosis of Brain Death (BD). 15 BD patients were submitted to the auditory brain stem response (ABR); in 7 cases somatosensory evoked potentials from the medial nerve (SEP) were also recorded. The ABR was absent in 11 cases (73.3%), while in 3 cases only the I wave was present (20%); in one case the low-voltage I-V waves were present. Regarding the SEP, in 3 cases (42.9%) only the N9-N13 and P9-P13 waves were present, while in another 3 cases (42.9%) a N13/P13 dissociation was observable. In the remaining case, which presented a still reproducible I-V interval, the SEP was normal, thus excluding the diagnosis of BD. The ABR and the SEP, which are not roughly influenced by general anaesthetics and sedatives, are thus helpful in diagnosing BD. The SEP seems able to supply useful information more frequently than the ABR, but their combined use can guarantee maximum security of excluding false positives. PMID:3194649

Facco, E; Caputo, P; Casartelli Liviero, M; Munari, M; Toffoletto, F; Fabiani, F; Giron, G

1988-01-01

101

Evoked trigeminal nerve potential in chronic trichloroethylene intoxication  

SciTech Connect

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.

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

1982-06-01

102

The effect of preterm birth on vestibular evoked myogenic potentials in children  

PubMed Central

Background: Preterm birth is a significant global health problem with serious short- and long-term consequences. This study examined the long term effects of preterm birth on vestibular evoked myogenic potentials (VEMPs) among preschool-aged children. Methods: Thirty-one children with preterm and 20 children with term birth histories aged 5.5 to 6.5 years were studied. Each child underwent VEMPs testing using a 500 Hz tone-burst stimulus with a 95 dB nHL (normal hearing level) intensity level. Results: The mean peak latencies of the p13 and n23 waves in the very preterm group were significantly longer than for the full-term group (p? 0.041). There was a significant difference between very and mildly preterm children in the latency of peak p13 (p= 0.003). No significant differences existed between groups for p13-n23 amplitude and the interaural amplitude difference ratio. The tested ear and gender did not affect the results of the test. Conclusion: Prolonged VEMPs in very preterm children may reflect neurodevelopmental impairment and incomplete maturity of the vestibulospinal tract (sacculocollic reflex pathway), especially myelination. VEMPs is a non-invasive technique for investigating the vestibular function in young children, and considered to be an appropriate tool for evaluating vestibular impairments at the low brainstem level. It can be used in follow-ups of the long-term effects of preterm birth on the vestibular system.

Eshaghi, Zahra; Jafari, Zahra; Shaibanizadeh, Abdolreza; Jalaie, Shohreh; Ghaseminejad, Azizeh

2014-01-01

103

Automatic denoising of single-trial evoked potentials.  

PubMed

We present an automatic denoising method based on the wavelet transform to obtain single trial evoked potentials. The method is based on the inter- and intra-scale variability of the wavelet coefficients and their deviations from baseline values. The performance of the method is tested with simulated event related potentials (ERPs) and with real visual and auditory ERPs. For the simulated data the presented method gives a significant improvement in the observation of single trial ERPs as well as in the estimation of their amplitudes and latencies, in comparison with a standard denoising technique (Donoho's thresholding) and in comparison with the noisy single trials. For the real data, the proposed method largely filters the spontaneous EEG activity, thus helping the identification of single trial visual and auditory ERPs. The proposed method provides a simple, automatic and fast tool that allows the study of single trial responses and their correlations with behavior. PMID:23142653

Ahmadi, Maryam; Quian Quiroga, Rodrigo

2013-02-01

104

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

PubMed

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

Wu, Zhenghua; Yao, Dezhong

2008-10-01

105

Somatosensory evoked potentials in workers exposed to toluene and styrene.  

PubMed Central

Somatosensory evoked potentials (SEPs) were used to evaluate possible subclinical impairment of the nervous system due to occupational exposure to toluene and styrene. A group of 36 rotogravure printers with severe exposure to toluene, 20 workers with severe exposure to styrene in a glass laminate manufacturing plant, and a comparison group of healthy subjects were studied. The severity of exposure was documented by measurements of toluene and styrene concentrations in breathing zone air, by hippuric acid concentration in urine in the group exposed to toluene, and by urinary mandelic acid concentration in the group exposed to styrene. Somatosensory evoked potentials were measured by stimulation of the median nerve at the wrist and the tibial nerve at the ankle. Peripheral conduction velocities (CVs) in both extremities and central conduction time (CCT) after tibial nerve stimulation were significantly decreased in both exposed groups. Significantly prolonged latencies of peripheral and cortical SEPs to median nerve stimulation as well as cortical SEPs to tibial nerve stimulation were found in workers exposed to styrene. Some abnormalities in SEPs at peripheral or spinal and cortical levels were found in eight workers exposed to toluene and six workers exposed to styrene. Of these, in three workers exposed to toluene and two to styrene increased CCT and delayed latencies of cortical responses at normal conduction values in the periphery were found. A trend for increased frequency of abnormal SEPs with duration of exposure to toluene and styrene and alcohol abuse was found. Abnormalities in SEPs in the exposed groups are most probably of multifactorial origin. Central SEP abnormalities in both exposed groups could indicate early signs of subclinical dysfunction at spinal and cortical levels and could be due to toluene or styrene exposure probably potentiated by alcohol consumption in the group exposed to toluene. PMID:8329318

St?tkárová, I; Urban, P; Procházka, B; Lukás, E

1993-01-01

106

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. PMID:24069276

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

2013-01-01

107

A generalized subspace approach for estimating visual evoked potentials.  

PubMed

A "single-trial" signal subspace approach for extracting visual evoked potential (VEP) from the ongoing 'colored' electroencephalogram (EEG) noise is proposed. The algorithm applies the generalized eigendecomposition on the covariance matrices of the VEP and noise to transform them jointly into diagonal matrices in order to avoid a pre-whitening stage. The proposed generalized subspace approach (GSA) decomposes the corrupted VEP space into a signal subspace and noise subspace. Enhancement is achieved by removing the noise subspace and estimating the clean VEPs only from the signal subspace. The validity and effectiveness of the proposed GSA scheme in estimating the latencies of P100's (used in objective assessment of visual pathways) are evaluated using real data collected from Selayang Hospital in Kuala Lumpur. The performance of GSA is compared with the recently proposed single-trial technique called the Third Order Correlation (TOC). PMID:19163891

Kamel, Nidal; Yusoff, Mohd Zuki

2008-01-01

108

Bessel filtering of brain stem auditory evoked potentials.  

PubMed

It has been shown previously that conventional high-pass filtering of the brain stem auditory evoked potential (BAEP) results in significant wave form distortion. This distortion can be drastically reduced by using digital filters with zero-phase properties, but this approach requires the use of a digital computer. The Bessel filter is an approximation to a linear phase characteristic, and has the advantage that it may be implemented using analog circuitry. We have considered its use as an alternative-to-digital zero-phase filtering. For the low-pass case, the Bessel phase characteristic is approximately linear throughout the pass band. However, for the high-pass case there is significant phase non-linearity extending well into the pass band. Typical Bessel high-pass filters seriously distort the BAEP wave form; thus, these filters are not an acceptable alternative to the zero-phase digital approach. PMID:6164544

Doyle, D J; Hyde, M L

1981-04-01

109

[Significance of abnormally high somatosensory evoked potentials (SEV)].  

PubMed

Data found in the literature and our own observations prompted us to consider the possibility that abnormally enlarged Somatosensory Evoked Potentials (SEPs) may have a diagnostic and physiopathological significance, particularly in a group of diseases which include common clinical features of encephalopathy with stimuli-sensitive myoclonus and epilepsy, whatever their etiology may be (degenerative or storage disease, metabolic, toxic or post-hypoxic encephalopathy...). We discuss the amplitude, morphology, diagnostic and therapeutic contribution of these 'giant' SEPs and pathogenic assumptions with reference to 'cortical reflex myoclonus'. Studies of back-averaged encephalogram, SEPs and long-loop reflexes allow some illustration of a functional hyperreactivity of the sensori-motor cortex, but no conclusive demonstration of its origin. PMID:3934721

Gehin, P; Huttin, B; Brichet, B; Weber, M

1985-09-01

110

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. PMID:23650538

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

2013-01-01

111

Respiratory-Related Evoked Potentials During Sleep in Children  

PubMed Central

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

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

2008-01-01

112

P300 Evoked Potential in Patients with Mild Cognitive Impairment  

PubMed Central

CONFLICT OF INTEREST: NONE DECLARED Aim The aim of this study is to present differences of amplitude and latency of P300 wave between examinees with mild cognitive impairment and examinees from the control group. Methods A cross-section study was performed between April 1st and July 10th 2012, with the diagnosis of mild cognitive impairment as the main criterion for inclusion. In the twenty-two examinees who participated in the research, mild cognitive impairment was confirmed by neuropsychological testing, following which they were subjected to the examination of auditory evoked potentials. The control group consisting of 22 examinees, for which the lack of the same diagnosis was previously ascertained, was also subjected to the examination of auditory evoked potentials. The main findings were the differences in the latency and amplitude size of P300 wave targeted and non-targeted stimuli. Results The latency of P300 wave targeted stimuli in patients with mild cognitive impairment has, in statistical terms, proven to be significantly longer when compared to the control group. The average latency length in those with MCI amounted to 306.18 ms, whereas the latency in the control group came to 295.95 ms. Similarly, the latency length of non-targeted stimuli turned out to be statistically higher, with the length of 320.00 ms in the former group, and 301.36 ms in the latter. Amplitudes in patients with mild cognitive impairment were lower in comparison to the control group, with extremely low amplitudes recorded in 36.36% of patients. Conclusion In patients with mild cognitive impairment extended latency and lower amplitude of P300 wave are recorded. PMID:24039332

Medvidovic, Stipe; Titlic, Marina; Maras-Simunic, Marina

2013-01-01

113

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

1999-01-01

114

Mapping human brain networks with cortico-cortical evoked potentials.  

PubMed

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

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

2014-10-01

115

Post-exercise facilitation and depression of M wave and motor evoked potentials in healthy subjects  

Microsoft Academic Search

Objectives: To characterize so-called central fatigue, the effect of various levels of exercise on central and peripheral motor potentials were compared.Methods: Thirteen healthy subjects performed 4 levels of exercise following isometric dorsiflexion of the foot. Post-exercise recordings from the anterior tibial muscle of motor evoked potentials (MEP) evoked by transcranial magnetic stimulation (TMS) and M wave evoked by electrical stimulation

Marianne Lentz; Jřrgen Feldbćk Nielsen

2002-01-01

116

EFFECTS OF LOW TO MODERATE LEAD EXPOSURE ON BRAINSTEM AUDITORY EVOKED POTENTIALS IN CHILDREN  

EPA Science Inventory

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 impairments have been observed in P...

117

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

EPA Science Inventory

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

118

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

1998-01-01

119

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

Microsoft Academic Search

The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO2 laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in

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

2003-01-01

120

Safety of intraoperative transcranial electrical stimulation motor evoked potential monitoring.  

PubMed

This article reviews intraoperative transcranial electrical stimulation (TES) motor evoked potential (MEP) monitoring safety based on comparison with other clinical and experimental brain stimulation methods and clinical experience in more than 15000 cases. Comparative analysis indicates that brain damage and kindling are highly unlikely. There have been remarkably few adverse events. Pulse train TES-induced or coincidental seizures (n = 5) are rare, probably because of very brief (<0.03 second) stimuli, anesthesia, and the general absence of predisposing cerebral conditions. Soft bite blocks may prevent tongue or lip laceration (n = 29) or mandibular fracture (n = 1). Rare cardiac arrhythmia (n = 5) and intraoperative awareness (n = 1) may be coincidental. Minor scalp burns (n = 2) are rare. Although possible, no spinal epidural recording electrode complications or injuries resulting from TES-induced movement were found. There have been no recognized adverse neuropsychological effects, headaches, or endocrine disturbances. Comprehensive relative contraindications include epilepsy, cortical lesions, convexity skull defects, raised intracranial pressure, cardiac disease, proconvulsant medications or anesthetics, intracranial electrodes, vascular clips or shunts, and cardiac pacemakers or other implanted biomedical devices. Otherwise unexplained intraoperative seizures and possibly arrhythmias are indications to abort TES. With appropriate precautions in expert hands, the well-established benefits of TES MEP monitoring decidedly outweigh the associated risks. PMID:12477987

MacDonald, David B

2002-10-01

121

Auditory Evoked Potential Variability in Healthy and Schizophrenia Subjects  

PubMed Central

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

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

2010-01-01

122

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. PMID:21169909

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

2011-01-01

123

Preliminary results of the relationship between the binaural interaction component of the electrically evoked auditory brainstem response and interaural pitch comparisons in bilateral cochlear implant recipients  

PubMed Central

Objectives The purpose of this study was to investigate the relationship between electrophysiologic measures of the binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) and psychophysical measures of interaural pitch comparisons in Nucleus bilateral cochlear implant users. Design Data were collected for ten postlingually deafened adult cochlear implant users. Each subject conducted an interaural pitch-comparison task using a biphasic pulse train with a pulse rate of 1000 pulses per second (pps) at high stimulation levels. Stimuli were presented in a two-interval, two-alternative forced-choice procedure with roving current variations. A subgroup of four subjects repeated the task at low stimulation levels. BICs were measured using loudness balanced, biphasic current pulses presented at a rate of 19.9 pps for each subject by pairing the electrode 12 (out of 22 intracochlear electrodes) in the right ear with each of 11 electrodes spaced across the electrode array in the left ear. The BIC was measured at high stimulation levels in ten subjects and at low stimulation levels in seven subjects. Because of differences in stimulation rate used in BIC measures and interaural pitch comparisons, the actual stimulation levels were different in these two measures. The relationship between BIC responses and results of interaural pitch comparisons was evaluated for each of the individual subjects as well as at the group level. Evaluation was carried out separately for results obtained at high and low stimulation levels. Results There was no significant correlation between results of BIC measures and interaural pitch comparisons on either the individual or group levels. Lower stimulation level did not improve the relationship between these two measures. Conclusions No significant correlations between psychophysical measures of interaural pitch comparisons and electrophysiologic measures of the BIC of the EABR were found. The lack of correlation may be attributed to methods used to quantify the data, small number of subjects retested at low stimulation levels, as well as central processing components involved in the interaural pitch-comparison task. PMID:21730858

He, Shuman; Brown, Carolyn J.; Abbas, Paul J.

2011-01-01

124

AMPD2 Regulates GTP Synthesis and is Mutated in a Potentially-Treatable Neurodegenerative Brainstem Disorder  

PubMed Central

Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acids synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a new distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH), due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a new, potentially treatable early-onset neurodegenerative disease. PMID:23911318

Akizu, Naiara; Cantagrel, Vincent; Schroth, Jana; Cai, Na; Vaux, Keith; McCloskey, Douglas; Naviaux, Robert K.; Vleet, Jeremy Van; Fenstermaker, Ali G.; Silhavy, Jennifer L.; Scheliga, Judith S.; Toyama, Keiko; Morisaki, Hiroko; Sonmez, Fatma Mujgan; Celep, Figen; Oraby, Azza; Zaki, Maha S.; Al-Baradie, Raidah; Faqeih, Eissa; Saleh, Mohammad; Spencer, Emily; Rosti, Rasim Ozgur; Scott, Eric; Nickerson, Elizabeth; Gabriel, Stacey; Morisaki, Takayuki; Holmes, Edward W.; Gleeson, Joseph G.

2013-01-01

125

Neural origin of evoked potentials during thalamic deep brain stimulation.  

PubMed

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

2013-08-01

126

Median nerve somatosensory evoked potentials in medical students: Normative data  

PubMed Central

Background: The median nerve N20 component constitutes the initial response of the primary somatosensory cortex to somatosensory stimulation of the upper extremity. Knowledge of the underlying generators is important for basic understanding of the initial sequence of cortical activation. Materials and Methods: In the present study, normative data of cortical evoked potentials in particular of N20 wave onset and peak latencies by median nerve stimulation in a group of 100 medical students aged between 18 and 30 years were documented and the effect of physiological variables were studied. Descriptive statistics and Student t-test were used to analyze the healthy subjects and to compare N20 latencies for handedness, respectively. Regression analysis was used to show association between average N20 latencies and physiological variables from which regression formulae were calculated to predict normative values of these parameters. Results: The results of the study indicated that N20 onset and peak latency values are significantly affected by limb length at 95% confidence level. Height is showing as a significant factor affecting N20 onset latencies but it is probably because of high correlation of height with limb length. Age though on linear regression showed some significant correlation with N20 onset and peak latency, multiple regressions showed that it does not affect N20 onset and peak latencies in the presence of other variables. Handedness did not affect both N20 onset and peak latency values. Conclusion: Physiological variables do affect the N20 latencies and these should be standardized before usage for research in basic sciences at all age groups. PMID:24223371

Poornima, Siddaraju; Ali, Syed Sadat; Balaji, Pishey Ashwathnarayan; Shankar, Vinutha; Kutty, Karthiyanee

2013-01-01

127

Neural origin of evoked potentials during thalamic deep brain stimulation  

PubMed Central

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 (R2 = 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.

2013-01-01

128

Clinical correlation between degenerative spine disease and dermatomal somatosensory-evoked potentials in humans.  

PubMed

The relationship between clinical status and preoperative and intraoperative dermatomal somatosensory-evoked potentials was investigated as a function of test site. Results indicated that the specificity and sensitivity of dermatomal somatosensory-evoked potentials varied with level of involvement: L5 demonstrated greatest agreement with equal correlation at L3, L4, and S1. Variables that influenced correlation included history of previous surgeries, type of anesthetic used, interpretation criteria, and whether the patient was awake or asleep. It was concluded that dermatomal somatosensory-evoked potentials can provide the surgeon with diagnostic and intraoperative information regarding the functional integrity of single nerve root function. PMID:1862415

Owen, J H; Padberg, A M; Spahr-Holland, L; Bridwell, K H; Keppler, L; Steffee, A D

1991-06-01

129

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.

1979-01-01

130

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

PubMed

A stimulation method was employed by which chemosensory evoked potentials were recorded without tactile somatosensory contamination. The purpose of the study was to determine whether potential components evoked by stimulation of the chemoreceptors of the trigeminal nerve can be distinguished from those of the olfactory nerve. The stimulants (vanillin, phenylethyl alcohol, limonene, menthol, anethol, benzaldehyde, carbon dioxide and a mixture of vanillin and carbon dioxide) were presented in a randomized order to 13 volunteers. Chemosensory evoked potentials to substances which anosmics are unable to perceive (vanillin, phenylethyl alcohol) were termed olfactory evoked potentials; potentials to CO2, which effected no olfactory sensations were termed chemo-somatosensory potentials. Analysis of variance revealed that the different substances resulted in statistically significant changes in the amplitudes and latencies of the evoked potentials, and also in the subjective estimates of intensity. An increased excitation of the somatosensory system resulted in reduced latencies and enhanced amplitudes of the evoked potentials. Responses to the mixture of carbon dioxide and vanillin appeared significantly earlier (50-150 msec) than responses to either substance alone. PMID:2454788

Kobal, G; Hummel, C

1988-01-01

131

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

PubMed Central

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

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

2011-01-01

132

Myogenic potentials generated by a click-evoked vestibulocollic reflex  

Microsoft Academic Search

Electromyograms (EMGs) were recorded from surface electrodes over the sternomastoid muscles and averaged in response to brief (0.1 ms) clicks played through headphones. In normal subjects, clicks 85 to 100 dB above our reference (45 dB SPL: close to perceptual threshold for normal subjects for such clicks) evoked reproducible changes in the averaged EMG beginning at a mean latency of

J G Colebatch; G M Halmagyi; N F Skuse

1994-01-01

133

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

EPA Science Inventory

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

134

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

EPA Science Inventory

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

135

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

2002-01-01

136

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

2007-01-01

137

Facilitation of cortically evoked potentials with motor imagery during post-exercise depression of corticospinal excitability  

Microsoft Academic Search

This study examined whether muscle fatigue alters the facilitatory effect of motor imagery on corticospinal excitability. We aimed to determine if post-exercise depression of potentials evoked magnetically from the motor cortex is associated with alterations in internally generated movement plans. In experiment 1, motor-evoked potentials (MEPs) were recorded from two right hand and two right forearm muscles, at rest and during

Julia B. Pitcher; Alexandra L. Robertson; Emma C. Clover; Shapour Jaberzadeh

2005-01-01

138

Auditory evoked responses to rhythmic sound pulses in dolphins  

Microsoft Academic Search

The ability of auditory evoked potentials to follow sound pulse (click or pip) rate was studied in bottlenosed dolphins.\\u000a Sound pulses were presented in 20-ms rhythmic trains separated by 80-ms pauses. Rhythmic click or pip trains evoked a quasi-sustained\\u000a response consisting of a sequence of auditory brainstem responses. This was designated as the rate-following response. Rate\\u000a following response peak-to-peak amplitude

V. V. Popov; A. Y. Supin

1998-01-01

139

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

SciTech Connect

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

He, Fengsheng; Liu, Xibao; Yang, Shi; Zhang, Shoulin (Institute of Occupational Medicine, Beijing (China)); Xu, Guanghua; Fang, Guangchai; Pan, Xiaowen (Navy Hospital, Beijing (China))

1993-02-01

140

The comparative analyses of the auditory evoked potentials and color Doppler sonography findings in patients diagnosed with vertebrobasilar insufficiency.  

PubMed

Auditory evoked potentials (AEP) represent an electrophysiological method used in the diagnostics of pathological changes of the brainstem. Patients with vertebrobasilar insufficiency (VBI) show changes in the AEP-caused ischemia of the brain structures that generate their responses. The aim of the study was to determine the diagnostic significance and correlation among the findings of AEP in patients with VBI established by color Doppler sonography. The cross-sectional and prospective research included 48 inpatients and outpatients treated at the Clinic of Neurology, Clinical Center Nis. Ultrasound Doppler of blood vessels in the neck included an examination of the carotid blood vessels, the outcome and all sonographically available parts of the vertebral artery (VA) with particular emphasis on the intravertebral segment (V2). The morphological and hemodynamic characteristics of VA in this segment were monitored, and it was important to test the systolic velocity in two adjacent intervertebral spaces. Auditory evoked potentials were used to monitor the amplitudes, absolute latencies of waves I, II, III, IV, and V, as well as interwave latencies (IWLs) I-III, III-V, and I-V. There is statistically significant difference in the more frequent pathological finding of AEP in patients with higher degree of the reduced flow of VA established by color Doppler (P < 0·05) compared to patients with less reduction in the flow. Pathological findings of AEP are well correlated with pathological findings of VBI in color Doppler, and it may be applied as an additional and useful marker in diagnosis of VBI. PMID:24806547

Zivadinovic, Biljana; Stamenovi?, Jelena; Ljubisavljevic, Srdjan

2014-11-01

141

[Changes in somatosensory evoked potentials during EEG activation by bemegride in man].  

PubMed

The use of evoked potentials for the evaluation of neuronal mechanisms by which convulsant drugs activate epilepsy and produce seizure has been reported by many authors. Electrophysiological effects of bemegride with augmented responsivity of brain structure to sensory stimulation is well known, especially in experiments performed with implanted electrodes in animals. After recording evoked activity from parietal scalp following median nerve stimulation before and during 12 human EEG activations by bemegride, the authors find an increase in amplitude of cortical somatosensory evoked potentials. Changes in amplitude after diazepam administration are analysed, as well as morphological changes preceding and following grand mal seizures induced by bemegride administration. This variation in amplitude of evoked responses is compared with those recorded in animals with several convulsant drugs and in man affected with progressive myoclonic encephalopathies. A common action of these agents, beyond their effects on specific neurotransmitters (perhaps mediated by a blockade of neurotransmitter-induced chloride conductance increases), is discussed. PMID:4048612

Weber, M; Huttin, B; Gehin, P; Vespignani, H; Brichet, B

1985-07-01

142

Evaluation of the vestibular evoked myogenic potential during parabolic flight in humans  

Microsoft Academic Search

The purpose of this study was to investigate how gravity affects the vestibular evoked myogenic potential (VEMP). Eight healthy\\u000a subjects (seven men, one woman; age range 19–45 years) participated in experiments in which three different gravity levels\\u000a [microgravity (MG), normal gravity (NG), and hypergravity (HG)] were imposed during a parabolic flight procedure. The VEMP\\u000a was evoked in response to an intense

Hideo Shojaku; Yukio Watanabe; Masahito Tsubota; Naomi Katayama

2008-01-01

143

Prognostic value of electroencephalography and evoked potentials in the early course of malignant middle cerebral artery infarction.  

PubMed

Space-occupying brain edema may lead to a malignant course in patients with large middle cerebral artery infarction. Decompressive hemicraniectomy has to be initiated early to prevent further tissue damage. In this retrospective study, we analyzed electroencephalography (EEG) and evoked potentials (EPs), obtained within 24 h after onset of stroke, in 22 patients suffering from a large middle cerebral artery infarction. Our findings indicate a prognostic value of EEG and brainstem auditory EP (BAEP): the absence of delta activity and the presence of theta and fast beta frequencies within EEG-focus predicted a non-malignant course. In contrast, diffuse generalized slowing and slow delta activity in the ischemic hemisphere pointed to a malignant course. Likewise, pathological BAEP were correlated with a malignant course. The coexistence of background slowing and pathological BAEP showed the highest level of significance. In conclusion, our findings implicate an additional early application of electrophysiological methods in stroke patients. EEG and EP deliver useful information to select those patients who develop malignant edema. PMID:22538759

Burghaus, Lothar; Liu, Wei-Chi; Dohmen, Christian; Haupt, Walter F; Fink, Gereon R; Eggers, Carsten

2013-05-01

144

Assessing stimulus and subject influences on auditory evoked potentials and their relation to peripheral physiology in green treefrogs (Hyla cinerea).  

PubMed

Anurans (frogs and toads) are important models for comparative studies of communication, auditory physiology, and neuroethology, but to date, most of our knowledge comes from in-depth studies of a relatively small number of model species. Using the well-studied green treefrog (Hyla cinerea), this study sought to develop and evaluate the use of auditory evoked potentials (AEPs) as a minimally invasive tool for investigating auditory sensitivity in a larger diversity of anuran species. The goals of the study were to assess the effects of frequency, signal level, sex, and body size on auditory brainstem response (ABR) amplitudes and latencies, characterize gross ABR morphology, and generate an audiogram that could be compared to several previously published audiograms for green treefrogs. Increasing signal level resulted in larger ABR amplitudes and shorter latencies, and these effects were frequency dependent. There was little evidence for an effect of sex or size on ABRs. Analyses consistently distinguished between responses to stimuli in the frequency ranges of the three previously-described populations of afferents that innervate the two auditory end organs in anurans. The overall shape of the audiogram shared prominent features with previously published audiograms. This study highlights the utility of AEPs as a valuable tool for the study of anuran auditory sensitivity. PMID:25151643

Buerkle, Nathan P; Schrode, Katrina M; Bee, Mark A

2014-12-01

145

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

PubMed

The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to beats-evoked oscillations were determined and compared across beat types, beat frequencies and base (carrier) frequencies. All stimuli evoked tone-onset components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude in response to acoustic than to binaural beats, to 250 than to 1000 Hz base frequency and to 3 Hz than to 6 Hz beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left temporal lobe areas. Differences between estimated sources of potentials to acoustic and binaural beats were not significant. The perceptions of binaural beats involve cortical activity that is not different than acoustic beats in distribution and in the effects of beat- and base frequency, indicating similar cortical processing. PMID:20123120

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

2010-04-01

146

Cortical responses of vestibular reactions measured by topographic brain mapping and vestibular evoked potentials.  

PubMed

With the brain electrical activity mapping, we started to create typical patterns of potentials distributions on the scalp during various neurootological experiments. We are applying this technique for spatiotemporal analysis of cerebral evoked potentials due to vestibular stimulation. We obtain the vestibular evoked potentials (VbEP) using for the stimulation, the rotatory chair. We control it, with an external computer, that by means of an interactive program builds different sort of stimuli varying each one of the stimulus components. The electrodes are distributed on the scalp in agreement with the international system 10/20. We recognize with security, 4 positive-negative waves in a period among 70 to 490 ms. We designate the waves N1, N2, P2, N3 and N4. Vestibular evoked potentials is a newly developed tool, which we also can utilize for differentiating central and peripheral vestibular diseases. PMID:8749099

Bertora, G O; Bergmann, J M

1995-01-01

147

Sex-related hemispheric lateralization of electrical potentials evoked by arousing negative stimuli  

Microsoft Academic Search

Recent studies suggest that both sex and cerebral hemisphere influence brain mechanisms associated with emotional memory. Here we used evoked potentials to examine the influence of sex and hemisphere on brain responses to emotional stimuli. Given that the P300 component of the event-related brain potential (ERP) is considered a cognitive neuroelectric phenomenon, we compared left and right hemisphere P300 responses

Antonella Gasbarri; Benedetto Arnone; Assunta Pompili; Francesca Pacitti; Claudio Pacitti; Larry Cahill

2007-01-01

148

The effects of adult male mouse urine odor on evoked potentials in adult female mice  

E-print Network

OF SCIENCE MAY 1985 Major Subject: Bioengineering THE EFFECTS OF ADULT MALE MOUSE URINE ODOR ON EVOKED POTENTIALS IN ADULT FEMALE MICE A Thesis by TROY EDWIN BROWN Approved as to style and content by: Jon F. Hunter (Co ? C airman of Committee... OF SCIENCE MAY 1985 Major Subject: Bioengineering THE EFFECTS OF ADULT MALE MOUSE URINE ODOR ON EVOKED POTENTIALS IN ADULT FEMALE MICE A Thesis by TROY EDWIN BROWN Approved as to style and content by: Jon F. Hunter (Co ? C airman of Committee...

Brown, Troy Edwin

2012-06-07

149

Predictability of Painful Stimulation Modulates the Somatosensory-Evoked Potential in the Rat  

PubMed Central

Somatosensory-evoked potentials (SEPs) are used in humans and animals to increase knowledge about nociception and pain. Since the SEP in humans increases when noxious stimuli are administered unpredictably, predictability potentially influences the SEP in animals as well. To assess the effect of predictability on the SEP in animals, classical fear conditioning was applied to compare SEPs between rats receiving SEP-evoking electrical stimuli either predictably or unpredictably. As in humans, the rat’s SEP increased when SEP-evoking stimuli were administered unpredictably. These data support the hypothesis that the predictability of noxious stimuli plays a distinctive role in the processing of these stimuli in animals. The influence of predictability should be considered when studying nociception and pain in animals. Additionally, this finding suggests that animals confronted with (un)predictable noxious stimuli can be used to investigate the mechanisms underlying the influence of predictability on central processing of noxious stimuli. PMID:23613862

Schaap, Manon W. H.; van Oostrom, Hugo; Doornenbal, Arie; Baars, Annemarie M.; Arndt, Saskia S.; Hellebrekers, Ludo J.

2013-01-01

150

Comparison of chirp versus click and tone pip stimulation for cervical vestibular evoked myogenic potentials.  

PubMed

The current study explored differences among cervical vestibular evoked myogenic potentials (cVEMP) that were evoked by CE-chirp and click and tone pip in healthy controls, and tried to explain the differences of cVEMP between the three of them. Thirty normal volunteers were used as subjects for CE-chirp and click and tone-pip (Blackman pip) stimuli. The latency of P1, N1, peak-to-peak P1-N1 amplitude, and cVEMP interaural difference were obtained and analyzed. The response rates of cVEMP were 93 % for click and 100 % for both Blackman pip and CE-chirp, respectively. The P1 and N1 latencies of cVEMP evoked by CE-chirp were the shortest, followed by click, with Blackman pip the longest (F = 6,686.852, P < 0.001). All indices of cVEMP evoked by the three stimuli showed no significant difference between the left and right ears or between genders. cVEMP responses were significantly different between the three stimuli. Compared with the currently used stimulus, CE-chirp can evoke cVEMP with shorter latencies and demonstrates increased speed and reliability. PMID:24178551

Wang, Bo-Chen; Liang, Yong; Liu, Xiao-Long; Zhao, Jing; Liu, You-Li; Li, Yan-Fei; Zhang, Wei; Li, Qi

2014-12-01

151

Otoacoustic Emissions, Auditory Evoked Potentials, and Traits Related to Sex and Sexual Orientation  

Microsoft Academic Search

A number of trait measures, possibly reflective of prenatal hormonal effects, were obtained in studies of otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) carried out with male and female heterosexual and homosexual\\/bisexual college students. Most of the measures were from a self-report questionnaire; others were from experimenters' ratings or cognitive tests (Mental Rotation Test and Water Level Test). The

John C. Loehlin; Dennis McFadden

2003-01-01

152

Development of a steady state visual evoked potential (SSVEP)-based brain computer interface (BCI) system  

Microsoft Academic Search

This paper describes the development of a synchronous, online brain computer interface (BCI) system based on detecting the steady-state visual evoked potential (SSVEP). The system includes a programmable visual stimulator, EEG amplifier with filter system, data acquisition card, and signal processing and classification algorithms. Two types of experiments were carried out; training experiments were conducted to determine three optimal frequencies

R. S. a Leow; F. a Ibrahim; M.b Moghavvemi

2007-01-01

153

Simultaneous recording of late and ultra-late pain evoked potentials in fibromyalgia  

Microsoft Academic Search

Objective: To characterize laser evoked potentials (LEP), pain psychophysics and local tissue response in fibromyalgia patients.Methods: LEP were recorded in 14 women with fibromyalgia in response to bilateral stimulation of tender and control points in upper limbs by 4 blocks of 20 stimuli at each point. Subsequently, heat pain thresholds were measured and supra-threshold magnitude estimations of heat pain stimuli

M Granot; D Buskila; Y Granovsky; E Sprecher; L Neumann; D Yarnitsky

2001-01-01

154

Steady-state visually evoked potential topography during the Wisconsin card sorting test  

Microsoft Academic Search

This paper describes, for the first time, changes in steady-state visually evoked potential (SSVEP) topography associated with the performance of a computerised version of the Wisconsin card sort test (WCS). The SSVEP was recorded from 64 scalp sites and was elicited by a 13 Hz spatially uniform visual flicker presented continuously while 16 subjects performed the WCS. In the WCS,

R. B. Silberstein; j. Ciorciari; A. Pipingas

1995-01-01

155

Evoked potentials in full-term and premature infants: a comparative study  

Microsoft Academic Search

In this study the maturation of the central nervous system of full-term and premature infants were investigated electrophysiologically. The subjects were 16 full-term and 15 premature infants. Neurologic examination, psychometric tests, and measurement of evoked potentials were carried out periodically in babies who had no birth trauma, metabolic disorder, or intrauterine infection. Neurophysiologic comparison of the results was evaluated. As

Serap Uysal; Yavuz Renda; Meral Topçu; Gül?en Erdem; Rafiye Karacan

1993-01-01

156

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

EPA Science Inventory

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

157

Differential effects of cocaine, alcohol, and nicotine dependence on olfactory evoked potentials  

Microsoft Academic Search

Olfactory evoked potentials (OEP) were elicited by odorous and nonodorous stimuli in 50 adult subjects: 26 subjects with histories of either cocaine (n = 19) or alcohol (n = 7) dependence, 10 with histories of nicotine but no other drug dependence, 2 with clinical anosmia of peripheral origin, and 12 subjects without drug or olfactory disorders. The presentation of nonodorous

Lance O. Bauer; April E. Mott

1996-01-01

158

Analysis of gender based differences in auditory evoked potentials among healthy elderly population  

PubMed Central

Background: Influence of gender on auditory evoked potentials is contentious. Although there are quite a few studies documenting the gender as an influencing factor on auditory evoked potentials in younger subjects, but there is a lack of similar studies among elderly population. The present study was conducted to find out the pattern of gender based differences in auditory evoked potentials among healthy elderly subjects. Materials and Methods: A cross-sectional study was conducted on age matched, healthy males (n = 35) and females (n = 34), aged 50-70 years. The measures included latencies of waves I-V and interpeak latencies (IPL) I-III, III-V and I-V separately for both ears. Data was analyzed statistically using Students unpaired t-test, using Statistical Package for Social Sciences software v13.0. Results: The values of all the latencies and IPL for both the ears were non-significantly higher (P > 0.05) in males as compared to females. These results may be attributed to the differences in head circumference between both the genders and to the changed hormonal milieu of sex hormones after menopause. Conclusions: Statistical insignificance of latencies among male and female elderly subjects excludes gender as an influencing factor on auditory evoked potentials in this age group. PMID:25371865

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

2014-01-01

159

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

2003-01-01

160

A Steady State Visually Evoked Potential Investigation of Memory and Ageing  

ERIC Educational Resources Information Center

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

Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

2009-01-01

161

Vestibular-evoked myogenic potentials in two patients with Ramsay Hunt syndrome  

Microsoft Academic Search

We report on the function of the inferior vestibular nerve, as monitored by the vestibular-evoked myogenic potentials (VEMP), in two patients suffering from Ramsay Hunt syndrome. Both the patients presented canal paresis (CP) and hearing loss, but in one patient normal VEMP was recorded while the other presented vagus nerve paralysis plus no VEMP response at the highest stimulus intensity

Susumu Saito; Kentaro Ochi; Takehiko Kobayashi; Natsuki Sugiura; Yasushi Komatsuzaki; Toru Ohashi

2003-01-01

162

Pattern electroretinogram and visual evoked potential amplitudes are influenced by different stimulus field sizes and scotomata  

Microsoft Academic Search

The pattern electroretinogram and the visual evoked potential were recorded simultaneously with various stimulus fields and artificial scotomata of increasing sizes. In contrast to an earlier study, a smaller check size (20') and two stimulus field sizes (20° × 20° and 10° × 10°) for the scotomata were used. With a concentric decreasing stimulus field, a reduction of both the

Armin Junghardt; Hannes Wildberger; Yves Robert; Bela Török

1993-01-01

163

Seeing the pain of others while being in pain: A laser-evoked potentials study  

Microsoft Academic Search

Seeing actions, emotions and feelings of other individuals may activate resonant mechanisms that allow the empathic understanding of others’ states. Being crucial for implementing pro-social behaviors, empathy is considered as inherently altruistic. Here we explored whether the personal experience of pain make individuals less inclined to share others’ pain. We used laser-evoked potentials (LEPs) to explore whether observation of painful

Massimiliano Valeriani; Viviana Betti; Domenica Le Pera; Liala De Armas; Roberto Miliucci; Domenico Restuccia; Alessio Avenanti; Salvatore Maria Aglioti

2008-01-01

164

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

1981-01-01

165

Cholinergic Pairing with Visual Activation Results in Long-Term Enhancement of Visual Evoked Potentials  

Microsoft Academic Search

Acetylcholine (ACh) contributes to learning processes by modulating cortical plasticity in terms of intensity of neuronal activity and selectivity properties of cortical neurons. However, it is not known if ACh induces long term effects within the primary visual cortex (V1) that could sustain visual learning mechanisms. In the present study we analyzed visual evoked potentials (VEPs) in V1 of rats

Jun Il Kang; Elvire Vaucher; Teresa Serrano-Gotarredona

2009-01-01

166

Use of the evoked potential P3 component for control in a virtual apartment  

Microsoft Academic Search

Virtual reality (VR) may prove useful for training individuals to use a brain-computer interface (BCI). It could provide complex and controllable experimental environments during BCI research and development as well as increase user motivation. In the study reported here, we examined the robustness of the evoked potential P3 component in virtual and nonvirtual environments. We asked subjects to control several

Jessica D. Bayliss

2003-01-01

167

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

EPA Science Inventory

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

168

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

PubMed

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

2014-02-01

169

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

EPA Science Inventory

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

170

Attention-Related Effects on Somatosensory Evoked Potentials in College Students at High Risk for Psychopathology  

Microsoft Academic Search

Attention directed to a stimulus elicits a late positive wave in the evoked potential, which has consistently been shown to be of lower than normal amplitude in schizophrenic patients. This study aimed to determine whether a similar deviation from normal occurs in nonpatient college students with extremely high scores on Chapman's Physical Anhedonia (AN) and Perceptual Aberration (PA) Scales. Individuals

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

1985-01-01

171

Misrouting of the Optic Nerves in Albinism: Estimation of the Extent with Visual Evoked Potentials  

E-print Network

Misrouting of the Optic Nerves in Albinism: Estimation of the Extent with Visual Evoked Potentials albinism a part of the temporal retina projects abnormally to the contralateral hemisphere. An objec- tive recorded in 16 subjects with albinism and in 16 controls from occipital electrodes to pat- tern

Morland, Antony

172

Long-Term Replicability of EEG Spectra and Auditory Evoked Potentials in Schizophrenic and Normal Subjects  

Microsoft Academic Search

The spectral characteristics and average, auditory evoked potentials (AEPs) were determined from EEGs repeatedly recorded over a span of several years. Data from a vertex lead is presented for 4 chronic schizophrenic patients and 5 normal subjects. Measurements were made under identical conditions. For each subject characteristic spectra and AEPs were exhibited despite the passage of time. Patients had recordings

Kenneth Lifshitz; Kai L. Lee; Samuel Susswein

1987-01-01

173

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

1995-01-01

174

MMN And P3 Auditory Evoked Potentials within and Across Phonetic Categories.  

National Technical Information Service (NTIS)

The mismatch negativity (MNfN) and P3O0 of the auditory evoked response potentials were studied within and across phonetic categories of /ba/ and /pa/ differing in voice onset time. The MMN and P300 responses were present in all within and across phonetic...

M. A. Stokes

1995-01-01

175

ALTERATIONS IN FLASH EVOKED POTENTIALS (FEPS) IN RATS PRODUCED BY 3,3'-IMINODIPROPIONITRILE (IDPN)  

EPA Science Inventory

-3,-3'-iminodiproprionitrile (IDPN) is a neurotoxicant that produces changes in flash evoked potentials (FEPs) 18 weeks after treatment (52). e examined dose and time-related effects of IDPN on FEPs at earlier time points than previously studied. dult male Long-Evans rats were gi...

176

Effects of Symptomatic Treatments on Cutaneous Hyperalgesia and Laser Evoked Potentials During Migraine Attack  

Microsoft Academic Search

Previously an amplitude enhancement of laser evoked potentials (LEPs) was detected during migraine attack: we further examined pain threshold to CO2 laser stimuli and LEPs during attacks, evaluating the effect of almotriptan, lysine-acetylsalicylate and placebo treatment on cutaneous hyperalgesia to thermal stimuli delivered by CO2 laser and on LEP components. Eighteen patients suffering from migraine without aura were analysed. They

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

2005-01-01

177

Specificity and functional impact of post-exercise depression of cortically evoked motor potentials in man  

Microsoft Academic Search

Magnetic stimulation of the motor cortex with electromyographic recordings from exercising muscles has shown corticospinal excitability to be depressed following exercise. We now investigate whether this depression spreads to non-exercising muscles and its influence on performance. Healthy volunteers made unilateral biceps curls to exhaustion and, in another later session, for 25% of the time to exhaustion. Bilateral motor-evoked potentials (MEPs)

A. T. Humphry; E. J. Lloyd-Davies; R. J. Teare; K. E. Williams; P. H. Strutton; N. J. Davey

2004-01-01

178

Blink Reflexes Elicited by Electrical, Acoustic and Visual Stimuli. II. Their Relation to Visual-Evoked Potentials and Auditory Brain Stem Evoked Potentials in the Diagnosis of Multiple Sclerosis  

Microsoft Academic Search

Blink reflexes, elicited by flashes of light, tone bursts and electrical stimuli, as well as checkerboard reversal visual-evoked potentials and brain stem auditory evoked potentials were investigated in 55 patients with different degrees of diagnostic probability of multiple sclerosis. It was demonstrated that electrically and acoustically elicited blink reflexes are simple but rather sensitive methods of indicating brain stem lesions.

W. Tackmann; T. Ettlin

1982-01-01

179

Auditory evoked potentials as a function of sleep deprivation  

Microsoft Academic Search

Event-related brain potentials (ERPs) were studied in subjects deprived of sleep over a 48-h test period to assess the effects of different durations of continuous wakefulness on ERP components and to determine whether changes in the ERP components were related to changes in performance. Forty subjects were randomly assigned to either an experimental (sleep deprived) group (n = 30) or

John Harsh; Pietro Badia

1989-01-01

180

ACUTE EFFECTS OF ETHANOL ON PATTERN REVERSAL AND FLASH-EVOKED POTENTIALS IN RATS AND THE RELATIONSHIP TO BODY TEMPERATURE  

EPA Science Inventory

The effects of acute ethanol treatment on flash and pattern reversal visual evoked potentials (FEPs and PREPs, respectively) were examined in three experiments using Long-Evans rats. The relationships of evoked potential parameters with blook ethanol concentration and body temper...

181

Optical studies of the biphasic modulatory effects of glycine on excitatory postsynaptic potentials in the chick brainstem and their embryogenesis  

Microsoft Academic Search

Multiple-site optical recording of transmembrane potential activity, using a voltage-sensitive dye, was employed to monitor neural activity from the nucleus tractus solitarius of the chick embryo. Optical signals related to glutamate-mediated excitatory postsynaptic potentials were evoked by a brief square current pulse applied with a microsuction electrode to the vagus nerve, and were recorded simultaneously from many sites in the

K. Sato; Y. Momose-Sato; A. Hirota; T. Sakai; K. Kamino

1996-01-01

182

Event related evoked potential responses in epileptic patients.  

PubMed

The effect of epilepsy on cognitive functions has been investigated in this study. The P300 auditory event related potentials (AERP), Wechsler Adult Performance Intelligence Scale (WAPIS--Indian Adaptation) & Digit Span Test (DST) have been used to assess the cognitive status. Twenty primary generalised epilepsy patients and 20 normal controls were subjected to WAPIS & DST testing and their AERP recorded. On comparative statistical analysis, epileptic subjects were found to have significantly higher N2 & P300 latencies and lower P300 amplitude, WAPIS-IQ scores & DST scores. These findings suggest that there is a general decline of cognitive functions in epileptics especially the memory, attention, concentration and speed of mental processing and as also corroborated by P300 and that P300 can be used as an additional sensitive parameter to assess the cognitive status. PMID:11214502

Tandon, O P; Duhan, P

2000-10-01

183

Temporary threshold shift, loudness, and auditory evoked potentials.  

PubMed

TTS2 of 20dB was produced in a group of subjects using a 1000 Hz pure tone. All TTS and related measurements were made at 1500 Hz. The recovery of TTS, and of TLS or 'temporary loudness shift' (measured against a reference tone at 20db, 40dB and 60dB SL in the opposite ear), as well as N1-P2 amplitude of the Vertex potential, were plotted. There was an orderly recovery of both TLS and TTS although the rate of recovery of the latter was noticeably more rapid. Recovery of N1-P2 amplitude was much less orderly, although it did recover in much the same way. When the amplitudes were measured at 40dB SL the recovery was more orderly and followed the course of TTS more closely. It was concluded that any relation between N1-P2 amplitude and growth of loudness was indirect. PMID:421358

Botte, M C; Beagley, H A; Chocholle, R

1979-02-01

184

PAS-Induced Potentiation of Cortical-Evoked Activity in the Dorsolateral Prefrontal Cortex  

PubMed Central

Neuroplasticity and long-term potentiation (LTP) in the dorsolateral prefrontal cortex (DLPFC) are considered important mechanisms in learning and memory, and their disruption may be related to the pathophysiology of several neuropsychiatric disorders. Paired associative stimulation (PAS) is a brain stimulation paradigm that produces enhanced activity in the human motor cortex that may be related to LTP. In a group of 15 healthy participants, we report on the potentiation of cortical-evoked activity in the human DLPFC using the combination of PAS and electroencephalography. In contrast, a PAS control condition did not result in potentiation in another group of nine healthy participants. We also demonstrate that PAS-induced potentiation of cortical-evoked activity is characterized by anatomical specificity that is largely confined to the site of stimulation. Finally, we show that PAS results in potentiation of ?- and ?-activity and ?-phase–?-amplitude coupling. These neurophysiological indices may be related to working memory, an important function of the DLPFC. To our knowledge, this is the first report of potentiation of cortical-evoked activity in the DLPFC. As this potentiation may be related to LTP, our findings provide a model through which neuroplasticity in health and disease states in the frontal cortex can be studied. PMID:23820586

Rajji, Tarek K; Sun, Yinming; Zomorrodi-Moghaddam, Reza; Farzan, Faranak; Blumberger, Daniel M; Mulsant, Benoit H; Fitzgerald, Paul B; Daskalakis, Zafiris J

2013-01-01

185

Ultraviolet irradiation of the eye and Fos-positive neurons induced in trigeminal brainstem after intravitreal or ocular surface transient receptor potential vanilloid 1 activation.  

PubMed

The interior structures of the eye are well supplied by the trigeminal nerve; however, the function of these afferent fibers is not well defined. The aim of this study was to use c-fos like immunohistochemistry (Fos-LI) to map the trigeminal brainstem complex after intravitreal microinjection or ocular surface application of capsaicin, a selective transient receptor potential vanilloid 1 (TRPV1) agonist in male rats under barbiturate anesthesia. The effect of ocular inflammation on Fos-LI was tested 2 or 7 days after UV irradiation of the eye. In non-inflamed controls, intravitreal capsaicin produced peaks of Fos-LI at the trigeminal subnucleus interpolaris/caudalis (Vi/Vcvl) transition and in superficial laminae at the caudalis/upper cervical cord (Vc/C1) junction regions. At the Vc/C1 junction intravitreal capsaicin induced Fos-LI in a dose-dependent manner, while at the Vi/Vcvl transition responses were similar after vehicle or capsaicin injections. Two days, but not 7 days, after UV irradiation intravitreal and ocular surface capsaicin-evoked Fos-LI at the Vc/C1 junction and nucleus tractus solitarius (NTS) were markedly enhanced, whereas the responses at the Vi/Vcvl transition were not different from non-inflamed controls. More than 80% of trigeminal ganglion neurons labeled after intravitreal microinjection of Fluorogold also expressed immunoreactivity for the TRPV1 receptor. These findings suggested that most intraocular trigeminal sensory nerves serve as nociceptors. The similar pattern and magnitude of Fos-LI after capsaicin suggested that TRPV1-responsive trigeminal nerves that supply intraocular and ocular surface tissues form a unified integrative circuit in the caudal brainstem. Intensity coding of capsaicin concentration and facilitation of Fos-LI expression after UV irradiation strongly supported the hypothesis that the Vc/C1 junction was critical for nociceptive processing related to ocular pain, whereas the Vi/Vcvl transition region likely served other functions in ocular homeostasis under naďve and inflamed conditions. PMID:20643195

Chang, Z; Okamoto, K; Tashiro, A; Bereiter, D A

2010-10-13

186

Value of somatosensory evoked potentials in saphenous entrapment neuropathy.  

PubMed Central

Neuralgia of the saphenous nerve (SN) is a rare clinical syndrome simulating a vascular disorder of the lower extremities. In four cases, the presenting complaint was persistent pain on the medial aspect of the knee. Examination revealed tenderness over the site of exit of the SN form the femoral canal. Femoral nerve motor conduction, quadriceps H-reflex and EMG of the leg muscles were normal. The sensory nerve action potential of the SN in the leg was not obtained in some patients, even in the unaffected leg. SEP were therefore preferred for diagnosis and performed at the infrapatellar and descending branches of the right and left SN and recordings from the Cz'-Fz electrode. Latency and amplitude differences were evaluated and compared with a control group of healthy subjects. An alteration in the SEP from one branch was observed on the painful side. Posterior tibial responses were normal. In one case, pain resolved immediately after neurolysis, confirming SN entrapment above the femoral canal, before its division. Pain resolved in two other cases and persisted in the last after medical treatment. SEP studies are valuable in the diagnosis of an isolated lesion of the SN. Images PMID:1619412

Tranier, S; Durey, A; Chevallier, B; Liot, F

1992-01-01

187

Possible confounding effects of strobe “clicks” on flash evoked potentials in rats  

Microsoft Academic Search

Flash evoked potentials (FEPs) undergo within-and between-session changes and are modified by auditory white noise (26). We examined whether an auditory potential produced by the “click” associated with the strobe discharge could be recorded, and if alterations in an auditory response could explain the within- and between-session changes in FEPs. We also examined differences between a frontal cortex or a

David W. Herr; Kim T. Vo; Deborah King; William K. Boyes

1996-01-01

188

Differences by sex, ear, and sexual orientation in the time intervals between successive peaks in auditory evoked potentials.  

PubMed

Auditory evoked potential (AEP) data from two studies originally designed for other purposes were reanalyzed. The auditory brainstem response (ABR), middle-latency response (MLR), and long-latency response (LLR) were measured. The latencies to each of several peaks were measured for each subject for each ear of click presentation, and the time intervals between successive peaks were calculated. Of interest were differences in interpeak intervals between the sexes, between people of differing sexual orientations, and between the two ears of stimulation. Most of the differences obtained were small. The largest sex differences were for interval I ? V in the ABR and interval N1 ? N2 of the LLR (effect sizes > 0.6). The largest differences between heterosexuals and nonheterosexuals were for the latency to Wave I in both sexes, for the interval Na ? Nb in females, and for intervals V ? Na and Nb ? N1 in males (effect sizes > 0.3). The largest difference for ear stimulated was for interval N1 ? N2 in heterosexual females (effect size ?0.5). No substantial differences were found in the AEP intervals between women using, and not using, oral contraceptives. Left/right correlations for the interpeak intervals were mostly between about 0.4 and 0.6. Correlations between the ipsilateral intervals were small; i.e., interval length early in the AEP series was not highly predictive of interval length later in the series. Interpeak intervals appear generally less informative than raw latencies about differences by sex and by sexual orientation. PMID:20875848

McFadden, Dennis; Hsieh, Michelle D; Garcia-Sierra, Adrian; Champlin, Craig A

2010-12-01

189

Relationships between behavior, brainstem and cortical encoding of seen and heard speech in musicians and non-musicians  

Microsoft Academic Search

Musicians have a variety of perceptual and cortical specializations compared to non-musicians. Recent studies have shown that potentials evoked from primarily brainstem structures are enhanced in musi- cians, compared to non-musicians. Specifically, musicians have more robust representations of pitch peri- odicity and faster neural timing to sound onset when listening to sounds or both listening to and viewing a speaker.

Gabriella Musacchia; Dana Strait; Nina Kraus

2008-01-01

190

Differential recovery of the electroretinogram, visually evoked cortical potential, and electrically evoked cortical potential following vitrectomy: implications for acute testing of an implanted retinal prosthesis.  

PubMed

To determine the extent to which electrophysiologic tests of the afferent visual pathway are affected by vitrectomy, the procedure was performed in 15 eyes of 11 adult Dutch-belted rabbits. An electroretinogram (ERG), visually evoked cortical potential (VECP), and electrically evoked cortical potential (EECP) were obtained preoperatively and sequentially after surgery. For electrical stimulations, biphasic impulses were delivered to the retina. Post-vitrectomy declines of 49, 25, and 41% from the median baseline amplitudes and increases of 13, 18, and 17% from the median baseline latency values were found for ERG, VECP, and EECP, respectively. At 90 min, 13 to 30% of eyes still had an amplitude more than 10% below baseline on at least one of the three tests, whereas 10 to 47% of eyes had an abnormal latency more than 10% above baseline on at least one of the three tests. Amplitudes were more likely than latencies to return to near baseline, but for eyes that remained subnormal, the decline was greater for amplitudes than latencies. Significant alterations in retinal function, manifested by declines in amplitudes and increases in latencies of the ERG, VECP, and EECP, persist in a large proportion of eyes up to 90 min post-vitrectomy. PMID:15558366

Montezuma, Sandra R; Rizzo, Joseph F; Ziv, Ofer R

2004-03-01

191

Why do stroke patients with negative motor evoked potential show poor limb motor function recovery?  

PubMed Central

Negative motor evoked potentials after cerebral infarction, indicative of poor recovery of limb motor function, tend to be accompanied by changes in fractional anisotropy values and the cerebral peduncle area on the affected side, but the characteristics of these changes have not been reported. This study included 57 cases of cerebral infarction whose motor evoked potentials were tested in the 24 hours after the first inspection for diffusion tensor imaging, in which 29 cases were in the negative group and 28 cases in the positive group. Twenty-nine patients with negative motor evoked potentials were divided into two groups according to fractional anisotropy on the affected side of the cerebral peduncle: a fractional anisotropy < 0.36 group and a fractional anisotropy ? 0.36 group. All patients underwent a regular magnetic resonance imaging and a diffusion tensor imaging examination at 1 week, 1, 3, 6 and 12 months after cerebral infarction. The Fugl-Meyer scores of their hemiplegic limbs were tested before the magnetic resonance and diffusion tensor imaging tions. In the negative motor evoked potential group, fractional anisotropy in the affected cerebral peduncle declined progressively, which was most obvious in the first 1–3 months after the onset of cerebral infarction. The areas and area asymmetries of the cerebral peduncle on the affected side were significantly decreased at 6 and 12 months after onset. At 12 months after onset, the area asymmetries of the cerebral peduncle on the affected side were lower than the normal lower limit value of 0.83. Fugl-Meyer scores in the fractional anisotropy ? 0.36 group were significantly higher than in the fractional anisotropy < 0.36 group at 3–12 months after onset. The fractional anisotropy of the cerebral peduncle in the positive motor evoked potential group decreased in the first 1 month after onset, and stayed unchanged from 3–12 months; there was no change in the area of the cerebral peduncle in the first 1–12 months after cerebral infarction. These findings confirmed that if the fractional anisotropy of the cerebral peduncle on the affected side is < 0.36 and the area asymmetries < 0.83 in patients with negative motor evoked potential after cerebral infarction, then poor hemiplegic limb motor function recovery may occur.

Song, Zhibin; Dang, Lijuan; Zhou, Yanling; Dong, Yanjiang; Liang, Haimao; Zhu, Zhengfeng; Pan, Suyue

2013-01-01

192

Atropine-sensitive and -insensitive components of the somatosensory evoked potential.  

PubMed

The evoked potential in primary somatosensory cortex changes with time. Short puffs of air administered to the nose of awake, quietly resting adult rats elicited potentials that could be altered by one of several treatments (saline, atropine methyl nitrate or atropine sulfate). The change produced by blocking muscarinic receptors in the central nervous system with atropine sulfate (100 mg/kg) was the largest, but control substances also altered the potential, suggesting that the gradual changes observed in the evoked potential 30 min after intraperitoneal injection may also be affected by factors such as the stress associated with injection itself and the blockade of peripheral muscarinic receptors. The changes observed in the evoked potential when central cholinergic receptors are blocked include a large shift towards positivity in the early components (between 18 and 64 ms with maxima at 20 and 47 ms) and a similarly significant shift towards negativity in the later components (between 90 and 208 ms with maxima at 115 and 157 ms). The actual changes observed during inactivation of central muscarinic receptors suggest that the role of acetylcholine during arousal is more than to simply bias the cortex towards greater excitability. Rather, the muscarinic receptors on inhibitory interneurons or on the dendritic terminals of pyramidal cells in superficial layers of cortex enhance the first intracortical synaptic events but reduce the population response at later times during the first 250 ms following a tactile stimulus. PMID:11489255

Dancause, N; Dykes, R W; Miasnikov, A A; Agueev, V

2001-08-10

193

The Auditory Brain-Stem Response to Complex Sounds: A Potential Biomarker for Guiding Treatment of Psychosis  

PubMed Central

Cognitive deficits limit psychosocial functioning in schizophrenia. For many patients, cognitive remediation approaches have yielded encouraging results. Nevertheless, therapeutic response is variable, and outcome studies consistently identify individuals who respond minimally to these interventions. Biomarkers that can assist in identifying patients likely to benefit from particular forms of cognitive remediation are needed. Here, we describe an event-related potential (ERP) biomarker – the auditory brain-stem response (ABR) to complex sounds (cABR) – that appears to be particularly well-suited for predicting response to at least one form of cognitive remediation that targets auditory information processing. Uniquely, the cABR quantifies the fidelity of sound encoded at the level of the brainstem and midbrain. This ERP biomarker has revealed auditory processing abnormalities in various neurodevelopmental disorders, correlates with functioning across several cognitive domains, and appears to be responsive to targeted auditory training. We present preliminary cABR data from 18 schizophrenia patients and propose further investigation of this biomarker for predicting and tracking response to cognitive interventions. PMID:25352811

Tarasenko, Melissa A.; Swerdlow, Neal R.; Makeig, Scott; Braff, David L.; Light, Gregory A.

2014-01-01

194

A microprocessor controlled multi-channel evoked potential data acquisition system.  

PubMed

A stored program control system is described for the acquisition of evoked potential (EP) data. It is a small, portable and flexible system with a variety of input and output possibilities. The system presents a low cost solution to the problem of acquisition of evoked potential data. A novel method of converting and reducing sixteen channels of EEG analogue data to their digital equivalent is shown. It is adaptable for the inter active control of experiments and is sophisticated enough to deal with the complexities of experimental control as well as data manipulation. One of the major advantages of the system is that both the sequencing of the functions and their detailed make-up can be readily altered by programming to meet the individual requirements of any given situation. PMID:926156

Prasher, D K; Gergely, S

1977-11-01

195

Future ambulation prognosis as predicted by somatosensory evoked potentials in motor complete and incomplete quadriplegia  

Microsoft Academic Search

Objective: The purpose of this prospective study was to determine the efficacy of tibial somatosensory evoked potentials (SEPs) in predicting ambulation in tetraplegic individuals. Design: This was a prospective study of a cohort of cervical spinal cord—injured patients who had SEPs recorded within 72 hours to 2 weeks post-SCI and whose ambulation outcome was followed up to 2 years post-SCI.

Stanley R. Jacobs; Natalie K. Yeaney; Gerald J. Herbison; John F. Ditunno

1995-01-01

196

Modifications of event-related evoked potentials in physiological and pathological aging of the brain  

Microsoft Academic Search

We compared the parameters of acoustic event-related evoked potentials (ERP; tone stimulation) in healthy young and healthy\\u000a aged persons with those in patients suffering from Alzheimer’s disease (groups 1–3, respectively). It was found that the mean\\u000a peak latencies (PL) of the components P1-N2 in group 1 were longer than those in group 2, and the absolute values of the amplitudes

A. G. Snegir

1999-01-01

197

Visual evoked potentials in relation to factors of imprisonment in detention camps  

Microsoft Academic Search

Visual evoked potentials (VEPs) of the pattern shift reversal type were determined in a representative group of 57 prisoners of war (POWs) released in 1992 from detention camps in former Yugoslavia. The parameters were correlated with the conditions in four camps (1–4). All subjects were male, with a mean age of 34.75 years (SD ± 8.92), average length of imprisonment

A. Vrca; V. Bozikov; Z. Brzovi?; R. Fuchs; M. Malinar

1996-01-01

198

Facial nerve motor-evoked potential monitoring during microvascular decompression for hemifacial spasm  

Microsoft Academic Search

ObjectiveTo determine whether monitoring facial nerve motor-evoked potentials (FNMEPs) elicited by transcranial electrical stimulation during microvascular decompression (MVD) for hemifacial spasm (HFS) is useful for predicting postoperative outcome.MethodsThe authors analysed FNMEP findings in 25 patients with HFS. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (152–450 V). FNMEPs were recorded from the orbicularis

Masafumi Fukuda; Makoto Oishi; Tetsuya Hiraishi; Yukihiko Fujii

2010-01-01

199

Intraoperative facial motor evoked potential monitoring with transcranial electrical stimulation during skull base surgery  

Microsoft Academic Search

Objective: To address the limitations of standard electromyography (EMG) facial nerve monitoring techniques by exploring the novel application of multi-pulse transcranial electrical stimulation (mpTES) to myogenic facial motor evoked potential (MEP) monitoring.Methods: In 76 patients undergoing skull base surgery, mpTES was delivered through electrodes 1cm anterior to C1 and C2 (M1–M2), C3 and C4 (M3–M4) or C3 or C4 and

Charles C. J. Dong; David B. MacDonald; Ryojo Akagami; Brian Westerberg; Ahmed AlKhani; Imad Kanaan; Maher Hassounah

2005-01-01

200

Energy of Brain Potentials Evoked During Visual Stimulus: A New Biometric?  

Microsoft Academic Search

\\u000a We further explore the possibility of using the energy of brain potentials evoked during processing of visual stimuli (VS)\\u000a as a new biometric tool, where biometric features representing the energy of high frequency electroencephalogram (EEG) spectra\\u000a are used in the person identification paradigm. For convenience and ease of processing of cognitive processing, in the experiments,\\u000a simple black and white drawings

Ramaswamy Palaniappan; Danilo P. Mandic

2005-01-01

201

Somatosensory evoked potentials in lesions of central structures of the skin-motor analyzer  

Microsoft Academic Search

To assess the role of different mechanisms in increasing the amplitude of the early components of cortical somatosensory evoked\\u000a potentials (SSEPs) in lesions of central structures of the skin-motor analyzer in humans, SSEPs of the hand cortical projection\\u000a zones (the points C?3 and C?4) and the spinal dorsal column nuclei (DCN) were recorded in parallel in response to trancutaneous electrostimulation

E. V. Damyanovich; T. V. Orlova

2006-01-01

202

Post-exercise depression of motor evoked potentials as a function of exercise duration  

Microsoft Academic Search

Post-exercise facilitation and post-exercise depression are phenomena described in motor evoked potentials (MEPs) elicited to transcranial magnetic stimulation. Brief, non-fatiguing muscle activation produces post-exercise facilitation, and prolonged fatiguing muscle activation produces post-exercise depression. We studied 12 normal subjects to determine whether post-exercise depression occurs before fatigue is reached. We recorded MEPs from the resting extensor carpi radialis muscle after increasing

Ali Samii; Eric M. Wassermann; Mark Hallett

1997-01-01

203

Absence of facilitation or depression of motor evoked potentials after contralateral homologous muscle activation  

Microsoft Academic Search

We have previously described post-exercise facilitation and post-exercise depression of motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS). To determine the presence of post-exercise facilitation after exercise of a contralateral muscle, MEPs were recorded from the resting right extensor carpi radialis (ECR) muscle while the left ECR muscle was activated, then immediately after brief left ECR activation, and, finally,

Ali Samii; Michael Cańos; Katsunori Ikoma; Eric M. Wassermann; Mark Hallett

1997-01-01

204

BODY TEMPERATURE-DEPENDENT AND INDEPENDENT ACTIONS OF CHLORDIMEFORM ON VISUAL EVOKED POTENTIALS AND AXONAL TRANSPORT IN OPTIC SYSTEM OF RAT  

EPA Science Inventory

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

205

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

PubMed

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

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

2013-01-15

206

Laser acupuncture - innovative basic research: visual and laser-induced evoked potentials  

PubMed Central

Background and aims: Laser acupuncture is a therapeutic medical method. Innovative basic research is necessary within this fascinating area of research. This publication focuses on visual evoked potentials (VEP) elucidated by non-invasive and partially non-perceptible laser stimulation. Materials (Subjects) and Methods: The first part of this study presents systematic VEP-monitoring in connection with laser acupuncture and manual needle acupuncture in 40 healthy volunteers. The second part deals with bilateral non-perceptible laser needle (658 nm, 40 mW, 500 µm, 1 Hz) irradiation of the Neiguan acupoint (PC6) in a 26-year-old female healthy volunteer using a new 32-channel evoked potential analysis technique. Results: We were not able to find significant changes in latency or amplitudes of VEPs during laser acupuncture within the first part of the study. However in the second part we report about human cerebral evoked potentials after non-perceptible laser stimulation. Conclusions: The findings indicate that exposure to laser needle stimulation with a frequency of 1 Hz can modulate the ascending reticular activating system. Further studies are necessary to confirm or refute the very interesting findings. PMID:24511198

2012-01-01

207

Right-frontal slow negative potentials evoked by occipital TMS are reduced in NREM sleep.  

PubMed

Occipital transcranial magnetic stimulation applied in a task-free experimental setup leads to enhanced relative negativity of frontally recorded evoked slow potentials under the influence of caffeine (Murd et al., 2010 [26]). We tested whether this increased negativity could be reversed when a similar magnetic stimulation is applied during quiet sleep where consciousness is absent. Consistently with the hypothesis, non-REM sleep led to relative more positive slow brain potentials, compared to wakefulness. This effect was lateralized to the right hemisphere. We conclude that TMS indeed elicits slow negative potentials in higher arousal states, but the effect has hemispheric specificity depending on how arousal is manipulated. PMID:21335058

Stamm, Mihkel; Aru, Jaan; Bachmann, Talis

2011-04-15

208

[Laser evoked potentials as a method of evaluating the function of small fibres - application technique and clinical implications].  

PubMed

Laser evoked potentials (LEPs) are one of the few neurophysiological methods available whose purpose is to evaluate the functions of small fibres' sensory pathways Ad and C. This non-invasive technique is applied at the present time in diagnosing small fibre neuropathy. In order to record distinctive and repetitive evoked potentials from the surface of the skull, the skin of the dorsal surface of the hands and feet is stimulated with laser thermal, nociceptive stimuli. The main cortical laser-evoked potential is a complex of components N2-P2. Evaluation of the registered potentials in- cludes their morphology with shape, latency and amplitude. Up to now, laser evoked potentials have not been performed in Poland. PMID:19742396

Fila, Micha?; Bogucki, Andrzej

2009-01-01

209

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. PMID:25029581

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

2014-01-01

210

Generators of Visual Evoked Potentials for Faces and Eyes in the Human Brain as Determined by Dipole Localization  

Microsoft Academic Search

Human visual evoked potentials were recorded during presentation of photos of human and animal faces and various face features. Negative waves with approximate peak latencies of 165 msec (N170) were bilaterally recorded from the occipito-temporal regions. Mean peak latencies of the N170 were shorter for faces than eyes only. Analyses of amplitudes of evoked potentials indicated that the N170 elicited

Takashi Shibata; Hisao Nishijo; Ryoi Tamura; Keiichi Miyamoto; Satoshi Eifuku; Shunro Endo; Taketoshi Ono

2002-01-01

211

[Exploration of the auditory system in humans: From click to speech auditory brainstem responses].  

PubMed

There is a growing and unprecedented interest in the objective evaluation of the subcortical processes that are involved in speech perception, with potential clinical applications in speech and language impairments. Here, we review the studies illustrating the development of electrophysiological methods for assessing speech encoding in the human brainstem: from the pioneer recordings of click-evoked auditory brainstem responses (ABR), via studies of frequency-following responses (FFR) to the most recent measurements of speech ABR (SABR) or ABR in response to speech sounds. Recent research on SABR has provided new insights in the understanding of subcortical auditory processing mechanisms. The SABR test is an objective and non-invasive tool for assessing individual capacity of speech encoding in the brainstem. SABR characteristics are potentially useful both as a diagnosis tool of speech encoding deficits and as an assessment tool of the efficacy of rehabilitation programs in patients with learning and/or auditory processing disorders. PMID:21093798

Richard, C; Jeanvoine, A; Veuillet, E; Moulin, A; Thai-Van, H

2010-01-01

212

Relationship between visual evoked potentials and subjective differences between emotional expressions in "face diagrams".  

PubMed

The relationship between visual evoked potentials resulting from substitution of one image of a human "face diagram" for another and assessment of perceived differences between the emotional expressions of these faces were studied. Emotions were altered by changing the curvature of the mouth and/or the slope of the brows. Unlike the traditional approach, in which visual evoked potentials are recorded in response to presentation of a single stimulus bearing a face image, visual evoked potentials in the present study were recorded as the response to instantaneous substitution of a reference stimulus with a test stimulus, and thus represented the direct response to the difference between the stimuli. A characteristic of this approach was the use of a series of functionally associated test stimuli, in which there was a monotonic increase in the difference between the test and references images in terms of the variable characteristics of the stimuli. Analysis revealed differences in the amplitudes of the P120, N180, and P230 peaks in leads O1, O2, P3, P4, T5, and T6, which demonstrated high levels of correlation both with a points-scale assessment of perceived differences between the emotional expressions of faces and with the physical (configurative) differences between images of the same faces as defined by the differences in the orientation angles of lines determining mouth curvature and brow angle. Responses were seen to differences between stimuli for both types of change in pairs of images, both going from reference image to test image and from test image to reference image. Changes in the interpeak amplitude of the P120-N180 potential in the temporal areas of both hemispheres provided the earliest electrophysiological measure of perceived differences between the emotional expressions of human faces. This suggests application of the spherical model for the perception of emotions to specify emotional facial expressions in terms of the activity of line orientation detectors. PMID:11693478

Izmailov ChA; Korshunova, S G; Sokolov, E N

2001-01-01

213

An introduction to the biophysics of the electrically evoked compound action potential.  

PubMed

A computational model of the electrically evoked compound action potential (ECAP) has been developed. In addition to being a useful research tool, it serves as an excellent introduction to the basic biophysics of ECAP recording techniques. ECAPs are modeled as a sum of single-fiber action potentials (SFAPs) in response to an electrical stimulus. Each SFAP is calculated from the potential induced at the recording site by the membrane currents arising on an axon as a spike propagates along it. The factors that alter SFAP and ECAP morphology and latency are discussed, as are the mechanisms of stimulus artefact and the advantages and limitations of different artefact-suppression techniques. The assumptions of the model are presented, as are potential ways of improving the physiologic data available from clinical recordings. Potential applications of this technology in the investigation of the biophysical mechanisms of the implanted cochlea are suggested. PMID:15732375

Rubinstein, Jay T

2004-12-01

214

Quantitative parameters of facial motor evoked potential during vestibular schwannoma surgery predict postoperative facial nerve function  

Microsoft Academic Search

Background  Facial motor evoked potential (FMEP) amplitude ratio reduction at the end of the surgery has been identified as a good predictor\\u000a for postoperative facial nerve outcome. We sought to investigate variations in FMEP amplitude and waveform morphology during\\u000a vestibular schwannoma (VS) resection and to correlate these measures with postoperative facial function immediately after\\u000a surgery and at the last follow-up.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Intraoperative

Marcus André Acioly; Alireza Gharabaghi; Marina Liebsch; Carlos Henrique Carvalho; Paulo Henrique Aguiar; Marcos Tatagiba

2011-01-01

215

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. PMID:24351768

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

2013-01-01

216

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

PubMed

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

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

2012-07-01

217

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. PMID:23548662

Vanegas, M Isabel; Blangero, Annabelle; Kelly, Simon P

2013-01-01

218

Lateral Geniculate Body Evoked Potentials Elicited by Visual and Electrical Stimulation  

PubMed Central

Purpose Blind individuals who have photoreceptor loss are known to perceive phosphenes with electrical stimulation of their remaining retinal ganglion cells. We proposed that implantable lateral geniculate body (LGB) stimulus electrode arrays could be used to generate phosphene vision. We attempted to refine the basic reference of the electrical evoked potentials (EEPs) elicited by microelectrical stimulations of the optic nerve, optic tract and LGB of a domestic pig, and then compared it to visual evoked potentials (VEPs) elicited by short-flash stimuli. Methods For visual function measurement, VEPs in response to short-flash stimuli on the left eye of the domestic pig were assessed over the visual cortex at position Oz with the reference electrode at Fz. After anesthesia, linearly configured platinum wire electrodes were inserted into the optic nerve, optic track and LGB. To determine the optimal stimulus current, EEPs were recorded repeatedly with controlling the pulse and power. The threshold of current and charge density to elicit EEPs at 0.3 ms pulse duration was about ±10 µA. Results Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes. The latency of P1 was more shortened as the electrical stimulation was closer to LGB. The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes. We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred. Conclusions EEPs and VEPs derived from visual-system stimulation were compared. The LGB-stimulated EEP wave demonstrated a similar pattern to the VEP waveform except implicit time, indicating prosthetic-based electrical stimulation of the LGB could be utilized for the blind to perceive vision of phosphenes. PMID:25120343

Choi, Chang Wook; Kim, Pan Sang; Shin, Sun Ae; Yang, Ji Yeon

2014-01-01

219

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 PMID:8544123

Schiller, J; Helmchen, F; Sakmann, B

1995-01-01

220

Extreme somatosensory evoked potential (ESEP): an EEG sign forecasting the possible occurrence of seizures in children.  

PubMed

In a population of 15,000 children it was found that tactile stimulation, mainly tapping on the soles or heels of the feet, could elicit high-voltage evoked potentials in the EEGs of 1% of them. A longitudinal study of 16 of these patients showed a stereotyped electroclinical evolution. At first, only extreme somatosensory evoked potential (ESEPs) were observed in nonepileptic children with normal EEG records (first period). Then, after a variable delay, spontaneous EEG abnormalities appeared, first only during sleep, and then also during wakefulness, usually as spikes involving the same parietal and midline regions where the ESEPs were evident (second and third periods). Seizures then began (fourth period) within 5 months to 2 years after the appearance of the interictal focal abnormalities. Such seizures were rare, but in some cases they were grouped in bouts that amounted to status epilepticus. The seizures were usually of the partial motor type, with adversion of the head, but infrequently they assumed the tonic-clonic type; they occurred mainly during the daytime. The fits were short-lived, however, and after a year had mostly disappeared, while the ESEPs and spontaneous interictal focal abnormalities sometime persisted for several year before disappearing, too. The subjects were otherwise neurologically and psychologically normal throughout the observation and follow-up period. PMID:6793354

de Marco, P; Tassinari, C A

1981-10-01

221

Evoked potentials and neuropsychological tests validate Positron Emission Topography (PET) brain metabolism in cognitively impaired patients.  

PubMed

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

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

2013-01-01

222

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. PMID:23526928

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

2013-01-01

223

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

PubMed

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

2014-02-01

224

Ground-truthing evoked potential measurements against behavioral conditioning in the goldfish, Carassius auratus  

NASA Astrophysics Data System (ADS)

Auditory evoked potentials (AEPs) have become commonly used to measure hearing thresholds in fish. However, it is uncertain how well AEP thresholds match behavioral hearing thresholds and what effect variability in electrode placement has on AEPs. In the first experiment, the effect of electrode placement on AEPs was determined by simultaneously recording AEPs from four locations on each of 12 goldfish, Carassius auratus. In the second experiment, the hearing sensitivity of 12 goldfish was measured using both classical conditioning and AEP's in the same setup. For behavioral conditioning, the fish were trained to reduce their respiration rate in response to a 5 s sound presentation paired with a brief shock. A modified staircase method was used in which 20 reversals were completed for each frequency, and threshold levels were determined by averaging the last 12 reversals. Once the behavioral audiogram was completed, the AEP measurements were made without moving the fish. The recording electrode was located subdermally over the medulla, and was inserted prior to classical conditioning to minimize handling of animal. The same sound stimuli (pulsed tones) were presented and the resultant evoked potentials were recorded for 1000-6000 averages. AEP input-output functions were then compared to the behavioral audiogram to compare techniques for estimating behavioral thresholds from AEP data.

Hill, Randy J.; Mann, David A.

2005-04-01

225

Brainstem tuberculosis.  

PubMed

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

2013-01-01

226

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+]. PMID:24303163

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

2013-01-01

227

Effect of anesthetic variables on dermatomal somatosensory-evoked potential monitoring in elective lumbar spinal surgery.  

PubMed

We studied 108 adult cases of elective lumbar surgery using dermatomal somatosensory-evoked potential (DSEP) monitoring to evaluate its usefulness due to concern over potential neurologic injury during pedicle screw insertion. Both surgeons used all of the necessary precautions required during surgery so that DSEP monitoring was not the "primary," but rather a backup system for operative security. Quality tracings were obtained in 71% of cases; anesthetic difficulties being the major cause of poor monitoring. There were no neurological complications related to pedicle screw insertion. We found that DSEP monitoring was an excellent method to verify intraoperative neurological status, but required a high degree of cooperation between the anesthesiologists, monitoring technician, and surgeons. In today's cost-containment environment, its usefulness is subjected to the expertise of the spine surgeon and the hospital setting. PMID:8605418

Coscia, M F; Trammell, T R; Popp, B; Gawande, S R; Fitzgerald, J; Scott, J R

1995-12-01

228

Application of wavelet based denoising techniques to rTMS evoked potentials.  

PubMed

This paper presents a new method of removing noise from the EEG response signal recorded during repetitive transcranial magnetic stimulation (rTMS). This noise is principally composed of the residual stimulus artifact and mV amplitude compound muscle action potentials recorded from the scalp muscles and precludes analysis of the cortical evoked potentials, especially during the first 15 ms post stimulus. The method uses the wavelet transform with a fourth order Daubechies mother wavelet and a novel coefficient reduction algorithm based on cortical amplitude thresholds. The approach has been tested and two methods of coefficient reduction compared using data recorded during a study of cortical sensitivity to rTMS at different scalp locations. PMID:23366986

Chrapka, Philip; de Bruin, Hubert; Hasey, Gary

2012-01-01

229

Possible confounding effects of strobe "clicks" on flash evoked potentials in rats.  

PubMed

Flash evoked potentials (FEPs) undergo within- and between-session changes and are modified by auditory white noise (26). We examined whether an auditory potential produced by the "click" associated with the strobe discharge could be recorded, and if alterations in an auditory response could explain the within- and between-session changes in FEPs. We also examined differences between a frontal cortex or a nasal reference electrode location on FEPs and auditory potentials. An auditory potential associated with the strobe discharge could be clearly recorded. This response was eliminated by the presence of 80 dB SPL masking white noise. However, the within- and between-session changes in FEPs could not be explained by modifications of the auditory potential. Animals whose ear drums were ruptured did not exhibit an auditory response, and their FEPs were similar to those of controls tested in the presence of masking white noise. A nasal reference electrode decreased the impact of auditory potentials on FEPs, but allow visual potentials (electroretinogram and optic tract activity) to influence FEPs. The data show that auditory potentials associated with the strobe discharge can be recorded from the visual cortex of rats, and that these auditory responses represent a possible confounding factor in the interpretation of toxicological studies employing FEPs. PMID:8838613

Herr, D W; Vo, K T; King, D; Boyes, W K

1996-02-01

230

Micro-Field Evoked Potentials Recorded from the Porcine Sub-Dural Cortical Surface Utilizing a Microelectrode Array  

PubMed Central

A sub-dural surface microelectrode array designed to detect microfield evoked potentials has been developed. The device is comprised of an array of 350-micron square gold contacts, with bi-directional spacing of 150 microns, contained within a polyimide Kapton material. Cytotoxicity testing suggests that the device is suitable for use with animal and human patients. Implementation of the device in animal studies revealed that reliable evoked potentials could be acquired. Further work will be needed to determine how these microfield potentials, which demonstrate selectivity for one eye, relate to the distribution of the ocular dominance columns of the occipital cortex. PMID:17298849

Kitzmiller, Joseph P.; Hansford, Derek J.; Fortin, Linda D.; Obrietan, Karl H.; Bergdall, Valerie K.

2007-01-01

231

Sensory-evoked LTP driven by dendritic plateau potentials in vivo.  

PubMed

Long-term synaptic potentiation (LTP) is thought to be a key process in cortical synaptic network plasticity and memory formation. Hebbian forms of LTP depend on strong postsynaptic depolarization, which in many models is generated by action potentials that propagate back from the soma into dendrites. However, local dendritic depolarization has been shown to mediate these forms of LTP as well. As pyramidal cells in supragranular layers of the somatosensory cortex spike infrequently, it is unclear which of the two mechanisms prevails for those cells in vivo. Using whole-cell recordings in the mouse somatosensory cortex in vivo, we demonstrate that rhythmic sensory whisker stimulation efficiently induces synaptic LTP in layer 2/3 (L2/3) pyramidal cells in the absence of somatic spikes. The induction of LTP depended on the occurrence of NMDAR (N-methyl-d-aspartate receptor)-mediated long-lasting depolarizations, which bear similarities to dendritic plateau potentials. In addition, we show that whisker stimuli recruit synaptic networks that originate from the posteromedial complex of the thalamus (POm). Photostimulation of channelrhodopsin-2 expressing POm neurons generated NMDAR-mediated plateau potentials, whereas the inhibition of POm activity during rhythmic whisker stimulation suppressed the generation of those potentials and prevented whisker-evoked LTP. Taken together, our data provide evidence for sensory-driven synaptic LTP in vivo, in the absence of somatic spiking. Instead, LTP is mediated by plateau potentials that are generated through the cooperative activity of lemniscal and paralemniscal synaptic circuitry. PMID:25174710

Gambino, Frédéric; Pagčs, Stéphane; Kehayas, Vassilis; Baptista, Daniela; Tatti, Roberta; Carleton, Alan; Holtmaat, Anthony

2014-11-01

232

Evaluation of evoked potentials and lymphocyte subsets as possible markers of multiple sclerosis: one year follow up of 30 patients.  

PubMed Central

Evoked potentials and T-lymphocyte helper/suppressor ratio (H/S) were evaluated serially together with neurological status in 30 definite multiple sclerosis patients to evaluate their possible role in monitoring disease progression. Evoked potentials in many cases reflected the clinical status of the pathways tested, but some exceptions were observed, probably due to subclinical relapses or physical factors. In some instances the occurrence of subclinical relapses was suggested by increased H/S ratios. Serial H/S values increased in parallel with clinical and subclinical relapses, and seemed to show specific patterns in relation to the type of clinical course (relapsing, stable, chronic progressive). Our results suggest that evoked potentials and H/S ratio serial analysis can contribute to a better assessment of the progress of multiple sclerosis. PMID:3489075

Ghezzi, A; Zaffaroni, M; Caputo, D; Montanini, R; Cazzullo, C L

1986-01-01

233

Evoked potential monitoring in carotid surgery: a review of 994 cases.  

PubMed

Intraoperative monitoring of brain function is desirable in carotid artery surgery to detect possible complications, but the monitoring methods must be simple to perform, sensitive, and reliable. Median nerve somatosensory evoked potential (SEP) monitoring fulfills these criteria. Between 1985 and 1990, we performed 994 operations of the carotid artery with SEP monitoring. In 92% of the cases, we were able to obtain viable SEP tracings. In seven cases, irreversible SEP loss was followed by a new neurologic deficit. In one case only, neurologic complications ensued without SEP loss. Although immediate intraoperative therapeutic options are limited, the monitoring enhances patient security by allowing intraoperative detection and postoperative analysis of complications. SEP monitoring appears to be at least as effective as conventional EEG monitoring. The viability, sensitivity, and reliability of newer methods, such as modified spectral EEG analysis, must be measured by this established procedure. PMID:1565239

Haupt, W F; Horsch, S

1992-04-01

234

The effect of experimental spinal cord edema on the spinal evoked potential.  

PubMed

Experimental spinal cord edema was successfully produced in the cat intumescentia cervicalis by the infusion method of Marmarou. The water content around the infusion site significantly increased to 75.9% from the normal value of 69.8% of white matter in the lateral column, with the infusion of 20 microliters of autoserum. The edema was observed for a length of ca.20 mm, spreading mainly longitudinally in the lateral column. The spinal evoked potential was measured four times on the course of infusion and the N1 peak latency at the end of infusion did not show any significant difference compared to the value before infusion. This model may contribute to basic understanding of pathophysiology of spinal cord edema by changing the nature and the volume of infusate, and the location of infusion, according to the experimental purpose. PMID:9779156

Tanaka, K; Kim, A; Naruse, H; Hakuba, A

1998-01-01

235

The effect of low-dose interferon treatment on visual evoked potentials.  

PubMed

Patients suffering from chronic viral hepatitis, treated with interferon alpha-2b in a dose of 3 million units trice weekly subcutaneously, were studied. The influence of interferon on the optic nerve was evaluated by measuring the P100 implicit time of the visual evoked potentials. The results before the treatment were compared with those after 6 and 12 months of therapy, as well as with those of normal subjects. There were statistically significant differences between the groups. Furthermore, in 10 of 56 eyes (17.8%) after 6 months of treatment, and 8 of 22 eyes (36.3%) after 12 months of treatment, the P100 was abnormally delayed. The long term neurovisual effects of low-dose interferon are currently under investigation. PMID:9682991

Moschos, M; Manesis, E; Panagakis, E; Brouzas, D; Hadziyannis, S; Theodossiadis, G

236

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. PMID:24720818

2014-01-01

237

Effects of spinal cord lesioning on somatosensory and neurogenic-motor evoked potentials.  

PubMed

Somatosensory (SEPs) and neurogenic-motor evoked potentials (NMEPs) were elicited from 16 hogs and two humans before, during, and after spinal cordotomy, dorsal, or ventral root rhizotomy. Results indicated that SEPs appear to be insensitive to the effects of motor tract lesioning in hogs and humans. In every case of motor paraplegia, SEPs remained unchanged in the presence of abnormal ischiatic/sciatic NMEPs. These results suggest that SEPs are not adequately sensitive to the functional status of the motor system in hogs and humans. Ischiatic/sciatic NMEPs remained unchanged after sensory tract lesioning, suggesting that these NMEPs are insensitive to the functional status of the sensory system. These results suggest that SEPs and NMEPs should be used in combination when monitoring spinal cord function during surgeries that place that structure at risk. PMID:2772714

Owen, J H; Jenny, A B; Naito, M; Weber, K; Bridwell, K H; McGhee, R

1989-07-01

238

Evoked potential latencies as a function of contrast: a system analytical approach.  

PubMed

That the latency of the pattern evoked potential (EP) increases as the stimulus contrast decreases can be understood as the result of, first, a low-pass filtering process of the (contrast) signal followed by, second, and nonlinear 'threshold' stage. We show here that by using this simple concept it is possible to estimate the shape of the 'unit step' response of the low-pass filter with the latency vs. contrast data. We show also that the step responses calculated from several subjects are in reasonable agreement if they are normalized with using the subjects' own contrast thresholds. Within experimental error, the response of a filter consisting of four low-pass first-order stages with a 10.5 Hz cut-off frequency gives a reasonable fit to our own data and to that of one other study (Musselwhite and Jeffreys, 1982). PMID:3996192

Pijn, J P; Estévez, O; van der Tweel, L H

1985-02-01

239

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 PMID:24396340

Luo, Jialie; Walters, Edgar T.; Carlton, Susan M.; Hu, Hongzhen

2013-01-01

240

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

PubMed

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

2014-09-01

241

In-vitro characterization of a cochlear implant system for recording of evoked compound action potentials  

PubMed Central

Background Modern cochlear implants have integrated recording systems for measuring electrically evoked compound action potentials of the auditory nerve. The characterization of such recording systems is important for establishing a reliable basis for the interpretation of signals acquired in vivo. In this study we investigated the characteristics of the recording system integrated into the MED-EL PULSARCI100 cochlear implant, especially its linearity and resolution, in order to develop a mathematical model describing the recording system. Methods In-vitro setup: The cochlear implant, including all attached electrodes, was fixed in a tank of physiologic saline solution. Sinusoidal signals of the same frequency but with different amplitudes were delivered via a signal generator for measuring and recording on a single electrode. Computer simulations: A basic mathematical model including the main elements of the recording system, i.e. amplification and digitalization stage, was developed. For this, digital output for sinusoidal input signals of different amplitudes were calculated using in-vitro recordings as reference. Results Using an averaging of 100 measurements the recording system behaved linearly down to approximately -60 dB of the input signal range. Using the same method, a system resolution of 10 ?V was determined for sinusoidal signals. The simulation results were in very good agreement with the results obtained from in-vitro experiments. Conclusions The recording system implemented in the MED-EL PULSARCI100 cochlear implant for measuring the evoked compound action potential of the auditory nerve operates reliably. The developed mathematical model provides a good approximation of the recording system. PMID:22531599

2012-01-01

242

Middle latency auditory evoked potential anaesthesia correlates of consciousness: practicality & constraints.  

PubMed

The hypothesis of this study is that significant differentiation of consciousness (CO) and unconsciousness (UNCO) is possible, using individual ML+AEP (10-140 msec) latency measures, within the context of a practical routine clinical depth of anaesthesia monitoring device. We have assessed individual latency band measures of the middle-latency auditory evoked potential (ML+AEP) as candidates to measure depth of CO or UNCO amongst a group of anaesthetised surgical patients. We have also compared ML+AEP correlates with conventional auditory evoked potential (AEP) index and bispectral index (BIS). This study investigates amplitude measures, limits and the practicality of using a single EEG channel ML+AEP recording system. ML+AEP amplitude-related correlates were assessed against CO and UNCO events during anaesthesia. ML+AEP measures were computed for each of the following AEP component-related latency time bins (LTB): Na;15-25msec, Pa;25-35 msec, TP41;35-45 msec; Pb/P1; 45-55 msec, N1;80-100 msec, N1;80-140 msec, and ML+AEP;0-140 msec. Twenty patients (aged 28-68 yrs) undergoing day surgery had their electroencephalography (EEG) monitored during binaural auditory stimulus presentation (6.8 clicks per second). The AEP grand mean waveform (AEPgmw) was computed for each consecutive stimulus AEP event, by way of averaging the previous 256 AEPs. The mean and SD amplitude associated with each of the ML+AEP ranges were computed for the whole study period and also for the predetermined events 1 to 13 (CO:1;2;3;12;13 and UNCO:4-11). Results included BIS data, measures derived from the AEPgmw across both the ML+AEP range (0-140 msec), and also individual LTB segments. PMID:17281025

Burton, D; Myles, Ps; Brown, I; Xu, M; Zilberg, E

2005-01-01

243

Assessing the Effect of Opium Dependence on Visual Evoked Potential (VEP) in Men  

PubMed Central

Background: Opium-dependence having different effects on the nervous system is a common problem, especially in the Middle East and Iran. The aim of this study is evaluating the effects of opium-dependence on visual evoked potential (VEP) in men. Methods: Thirty subjects with both chronic cigarette smoking and opium-dependence (group 1) and 30 subjects with only chronic cigarette smoking (group 2) were included in this cross-sectional case-control study and after urinary tests of opium, the pattern reversal visual evoked potentials (PRVEP) were recorded in the standard condition and variables such as N75, P100, N135 and amplitude were obtained and then analyzed with SPSS16. P value < 0.05 was assumed significant statistically. Findings: The mean of N75 (70.426 ± 22.028), P100 (115.457 ± 29.176) and N135 (165.402 ± 66.712) was not significantly different between the two groups. The mean of the amplitude of VEP in group 1 (6.856 ± 3.248) was significantly higher than group 2 (4.933 ± 2.50) (P < 0.05). Conclusion: Our study showed that chronic cigarette smoking and opium dependence have no significant effect on the late components of the VEP (N75, P100 and N135), but chronic cigarette smoking and opium-dependence together significantly increase the amplitude of VEP compared with chronic cigarette smoking alone, probably due to the chronic stimulatory effects of concomitant use of these two substances on the eyes and the visual nervous system. PMID:24494098

Shafa, Mohammad Ali; Hamzeei Moghaddam, Akbar; Sohrabi, Abdol Hamid; Karimianpour, Marzyeh

2010-01-01

244

Inhibitory effects of glutamate-stimulated astrocytes on action potentials evoked by bradykinin in cultured dorsal root ganglion neurons.  

PubMed

Patch-clamp and Ca2+-imaging techniques have revealed that astrocytes have dynamic properties including ion channel activity and release of neurotransmitters, such as adenosine triphosphate (ATP) and glutamate. Here, we used the patch-clamp technique to determine whether ATP and glutamate is able to modulate the bradykinin (BK) response in neurons cultured with astrocytes in the mouse dorsal root ganglia (DRG) in order to clarify the role of astrocytes in nociceptive signal transmission. Astrocytes were identified using a fluorescent anti-GFAP antibody. The membrane potential of astrocytes was about -39 mV. The application of glutamic acid (GA) to the bath evoked the opening of two types of Cl- channel in the astrocyte cell membrane with a unit conductance of about 380 pS and 35 pS in the cell-attached mode, respectively. ATP application evoked the opening of two types of astrocyte K+ channel with a unit conductance of about 60 pS and 29 pS, respectively. Application of BK to the neuron evoked an action potential (spike). Concomitant BK application with ATP increased the frequency of BK-evoked neuron spikes when neurons coexisted with astrocytes. Stimulation of BK with GA inhibited the BK-evoked spike under similar conditions. The application of furosemide, a potent cotransporter (Na+-K+-2Cl-) inhibitor, prior to stimulation of BK with GA blocked inhibition of the spike. It is thought that inhibition of the spike is related to Cl- movement from astrocytes. PMID:24733593

Suzuki, Kazuo; Ono, Minehisa; Tonaka, Kenji

2014-04-01

245

Characterization of the electrically-evoked compound action potential of the vestibular nerve  

PubMed Central

Objective We recorded intra-operative and post-operative electrically-evoked compound action potentials (ECAPs) in rhesus monkeys implanted with a vestibular neurostimulator. The objectives were to correlate the generation of slow-phase nystagmus or eye twitches induced by electrical stimulation of the implanted semicircular canal with the presence or absence of the vestibular ECAP responses, and to assess the effectiveness of ECAP monitoring during surgery to guide surgical insertion of electrode arrays into the canals. Design Four rhesus monkeys (a total of seven canals) were implanted with a vestibular neurostimulator modified from the Nucleus Freedom™ cochlear implant. ECAP recordings were obtained during surgery or at various intervals post-surgery using the Neural Response Telemetry™ feature of the clinical Custom Sound EP™ software. Eye movements during electrical stimulation of individual canals were recorded with a scleral search coil system in the same animals. Results Measurable vestibular ECAPs were observed intra-operatively or post-operatively in three implanted animals. Robust and sustained ECAPs were obtained in three monkeys at the test intervals of 0, 7, or >100 days post implantation surgery. In all three animals, stimulation with electrical pulse trains produced measurable eye movements in a direction consistent with the vestibulo-ocular reflex from the implanted semicircular canal. In contrast, electrically-evoked eye movements could not be measured in three of the seven implanted canals none of which produced distinct vestibular ECAPs. In two animals, ECAP waveforms were systematically monitored during surgery and the procedure proved crucial to the success of vestibular implantation. Conclusions Vestibular ECAPs exhibit similar morphology and growth characteristics to cochlear ECAPs from human cochlear implant patients. The ECAP measure is well correlated with the functional activation of eye movements by electrical stimulation post implantation surgery. The intra-operative ECAP recording technique is an efficient tool to guide the placement of electrode array into the semicircular canals. PMID:21192375

Nie, Kaibao; Bierer, Steven M.; Ling, Leo; Oxford, Trey; Rubinstein, Jay T.; Phillips, James O.

2012-01-01

246

Reduced visual evoked responses in multiple sclerosis patients with optic neuritis: comparison of functional magnetic resonance imaging and visual evoked potentials.  

PubMed

The limited application of functional magnetic resonance imaging (fMRI) for investigations of multiple sclerosis (MS) patients has already shown that deficits of the motor, cognitive and visual systems may be identified by differences in the patterns of activation in response to a suitable stimulus. In MS patients with unilateral optic neuritis, the area of activation in the primary visual cortex, measured by fMRI techniques, is dramatically reduced in response to stimulation of the affected eye. The latency of the major positive component of the visual evoked potential (VEP) recorded upon stimulation of the affected eye is significantly increased in these patients, as compared to the unaffected eye and normal volunteers. We have found a correlation between the neural response measured using fMRI and the latency of the VEP. fMRI signal responses have the potential to provide more detailed topographic information relating to functional deficits in MS. PMID:10408715

Gareau, P J; Gati, J S; Menon, R S; Lee, D; Rice, G; Mitchell, J R; Mandelfino, P; Karlik, S J

1999-06-01

247

Cyclopiazonic acid disturbs the regulation of cytosolic calcium when repetitive action potentials are evoked in Dionaea traps  

Microsoft Academic Search

Evoking of action potentials (APs) in the trap of Dionaea muscipula Ellis at intervals shorter than 20 s caused a gradual decrease in the amplitude of the APs. At longer intervals the amplitude was constant. The calcium ionophore A23187 (1 µM) caused a considerable decrease of AP amplitude. Pretreatment of a segment of the Dionaea trap with cyclopiazonic acid (CPA),

Kazimierz Trebacz; Marion B. Busch; Zygmunt Hejnowicz; Andreas Sievers

1996-01-01

248

Methylene blue potentiates stimulus-evoked fMRI responses and cerebral oxygen consumption during normoxia and hypoxia  

E-print Network

Methylene blue potentiates stimulus-evoked fMRI responses and cerebral oxygen consumption during Forepaw stimulation Methylene blue USP (MB) at low doses has metabolic-enhancing and antioxidant Methylene blue USP (MB) is a unique auto-oxidizing pharmaceutical drug that has a hormetic dose

Duong, Timothy Q.

249

Changes in the centrifugal gating effect on somatosensory evoked potentials depending on the level of contractile force  

Microsoft Academic Search

In this study, we investigated the somatosensory evoked potentials (SEPs) during the preparatory period of self-initiated plantar flexion at different force levels of muscle contraction and elucidated the mechanism behind the centrifugal gating effect on somatosensory information processing. We recorded SEPs following stimulation of the tibial nerve at the popliteal fossa during the preparatory period of a 20% maximal voluntary

T. Wasaka; H. Nakata; T. Kida; R. Kakigi

2005-01-01

250

Somatosensory evoked potential spinal cord monitoring reduces neurologic deficits after scoliosis surgery: results of a large multicenter survey  

Microsoft Academic Search

Neurologic deficits were compared to somatosensory evoked potential (SEP) spinal cord monitoring in a survey of spinal orthopedic surgeons. Experienced SEP spinal cord monitoring teams had fewer than one-half as many neurologic deficits per 100 cases compared to teams with relatively little monitoring experience. Experienced SEP monitoring teams also had fewer neurologic deficits than were seen in previous surveys of

Marc R. Nuwer; Edgar G. Dawson; Linda G. Carlson; Linda E. A. Kanim; John E. Sherman

1995-01-01

251

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

EPA Science Inventory

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

252

Nitroglycerin induces migraine headache and central sensitization phenomena in patients with migraine without aura: a study of laser evoked potentials  

Microsoft Academic Search

In migraineurs nitroglycerin (NTG) induces severe delayed headache, resembling spontaneous migraine attacks. The aim of the present study was to evaluate NTG laser evoked potentials (LEP) features amplitude and pain sensation to laser stimuli during NTG-induced headache. Nine patients were selected. Headache was induced by oral administration of 0.6 mg of NTG; signals were recorded through disk electrodes placed at

Marina de Tommaso; Giuseppe Libro; Marco Guido; Olimpia Difruscolo; Luciana Losito; Michele Sardaro; Rosanna Cerbo

2004-01-01

253

Exercise-induced depression of the diaphragm motor evoked potential is not affected by non-invasive ventilation  

Microsoft Academic Search

Whole body exercise is followed by a depression of the diaphragm motor evoked potential (MEP). It is unknown whether the change is due to diaphragm activity or whole body exercise. To test the hypothesis that exercise-induced MEP depression was related to diaphragm activity, we performed two experiments. The first examined the effect of whole body exercise, performed with and without

Mark J. Dayer; Sophie Jonville; Michelle Chatwin; Elisabeth B. Swallow; Raphael Porcher; Tarek Sharshar; Ewen T. Ross; Nicholas S. Hopkinson; John Moxham; Michael I. Polkey

2007-01-01

254

Post-exercise facilitation and depression of motor evoked potentials to transcranial magnetic stimulation: a study in multiple sclerosis  

Microsoft Academic Search

Objective: To evaluate motor cortex excitability changes by transcranial magnetic stimulation (TMS) following repetitive muscle contractions in patients with multiple sclerosis (MS); to state whether a typical pattern of post-exercise motor evoked potentials (MEPs) is related to clinical fatigue in MS.Methods: In 41 patients with definite MS (32 with fatigue and 9 without fatigue according to Fatigue Severity Scale) and

A Perretti; P Balbi; G Orefice; L Trojano; L Marcantonio; V Brescia-Morra; S Ascione; F Manganelli; G Conte; L Santoro

2004-01-01

255

The locus of color sensation: Cortical color loss and the chromatic visual evoked potential  

PubMed Central

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

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

2013-01-01

256

Sensitivity of Offset and Onset Cortical Auditory Evoked Potentials to Signals in Noise  

PubMed Central

Objective The purpose of this study was to determine the effects of SNR and signal level on the offset response of the cortical auditory evoked potential (CAEP). Successful listening often depends on how well the auditory system can extract target signals from competing background noise. Both signal onsets and offsets are encoded neurally and contribute to successful listening in noise. Neural onset responses to signals in noise demonstrate a strong sensitivity to signal-to-noise ratio (SNR) rather than signal level; however, the sensitivity of neural offset responses to these cues is not known. Methods We analyzed the offset response from two previously published datasets for which only the onset response was reported. For both datasets, CAEPs were recorded from young normal-hearing adults in response to a 1000-Hz tone. For the first dataset, tones were presented at seven different signal levels without background noise, while the second dataset varied both signal level and SNR. Results Offset responses demonstrated sensitivity to absolute signal level in quiet, SNR, and to absolute signal level in noise. Conclusions Offset sensitivity to signal level when presented in noise contrasts with previously published onset results. Significance This sensitivity suggests a potential clinical measure of cortical encoding of signal level in noise. PMID:24007688

Baltzell, Lucas S.; Billings, Curtis J.

2013-01-01

257

Effects of Acute Administration of Ketorolac on Mammalian Vestibular Sensory Evoked Potentials  

PubMed Central

The nonsteroidal antiinflammatory drug (NSAID) ketorolac is a candidate for use as a supplemental analgesic during major surgery in anesthetized rodents. The use of ketorolac during surgery is believed to reduce the anesthetic dose required to achieve and maintain an adequate surgical plane, thus improving the physiologic condition and survival of animals during long experimental procedures. Ketorolac has reported side effects that include dizziness, ear pain, hearing loss, tinnitus, and vertigo in humans, but ketorolac has not been reported to affect the vestibular system in animals. To investigate this possibility, we evaluated the acute effects of ketorolac on vestibular compound action potentials in C57BL/6 mice. Linear vestibular sensory-evoked potentials (VsEP) were recorded during the administration of ketorolac at doses 3 to 14 times the effective analgesic dose. VsEP results for ketorolac were compared with those from a control group maintained under anesthesia for the same period. Ketorolac did not significantly affect the temporal profiles of response latencies and amplitudes or the rate of change in response measures over time between controls and ketorolac-treated mice. These findings demonstrate that ketorolac can be used as an analgesic to supplement anesthesia in mice without concerns of modifying the amplitudes and latencies of the linear VsEP. PMID:23562034

Gaines, G Christopher; Jones, Timothy A

2013-01-01

258

Echo-location and evoked potentials of bats after ablation of inferior colliculus  

PubMed Central

1. Echo-location and evoked potentials of blinded Yuma bats (Myotis yumanensis) were studied before and after ablation of the inferior colliculus (I.C.). A task of obstacle-avoidance was given to the bats: hits and misses of strands in the flight path were counted. Orientation sounds emitted by the bats during flight were recorded. 2. Bilateral ablation of the dorso-medial region of I.C. including the internuclear cortex and commissure had no effect on obstacle-avoidance performance. The bats avoided even strands of 0·2 mm diameter with orientation sounds. 3. Bilateral ablation of the dorsal half of I.C. including the external nucleus (lateral cortex) also had no effect on echo-location. 4. Bilateral ablation of the ventral half of I.C. caused severe deficiency in ability to avoid obstacles. The main nucleus appeared to be very important for echo-location. When bilateral ablation including the main nucleus was moderate, the bats failed to avoid strands of less than 0·5 mm diameter in spite of detecting them, but avoided large obstacles such as 3·7 mm strands. With severe bilateral ablation including the main nucleus, the bats did not avoid even the 3·7 mm strands in spite of frequent emission of orientation sounds, but often avoided crashing into the wall. 5. Severe unilateral ablation of I.C. including the main nucleus and a part of the lateral lemniscus had no effect on ability to avoid obstacles. Since sound localization by such bats are not explained by Van Bergeijk's model based on Békésy's, a modification of Van Bergeijk's model has to be considered. 6. Of the positive evoked potentials recorded with an active electrode placed at the dorsal surface of I.C., the slow component with a 7-9 msec peak latency reflected activity of inferior collicular neurones, while the fast component (N4) with a 3 msec peak latency represented activity of ascending lateral lemniscal fibres. PMID:5387030

Suga, N.

1969-01-01

259

Echo-location and evoked potentials of bats after ablation of inferior colliculus.  

PubMed

1. Echo-location and evoked potentials of blinded Yuma bats (Myotis yumanensis) were studied before and after ablation of the inferior colliculus (I.C.). A task of obstacle-avoidance was given to the bats: hits and misses of strands in the flight path were counted. Orientation sounds emitted by the bats during flight were recorded.2. Bilateral ablation of the dorso-medial region of I.C. including the internuclear cortex and commissure had no effect on obstacle-avoidance performance. The bats avoided even strands of 0.2 mm diameter with orientation sounds.3. Bilateral ablation of the dorsal half of I.C. including the external nucleus (lateral cortex) also had no effect on echo-location.4. Bilateral ablation of the ventral half of I.C. caused severe deficiency in ability to avoid obstacles. The main nucleus appeared to be very important for echo-location. When bilateral ablation including the main nucleus was moderate, the bats failed to avoid strands of less than 0.5 mm diameter in spite of detecting them, but avoided large obstacles such as 3.7 mm strands. With severe bilateral ablation including the main nucleus, the bats did not avoid even the 3.7 mm strands in spite of frequent emission of orientation sounds, but often avoided crashing into the wall.5. Severe unilateral ablation of I.C. including the main nucleus and a part of the lateral lemniscus had no effect on ability to avoid obstacles. Since sound localization by such bats are not explained by Van Bergeijk's model based on Békésy's, a modification of Van Bergeijk's model has to be considered.6. Of the positive evoked potentials recorded with an active electrode placed at the dorsal surface of I.C., the slow component with a 7-9 msec peak latency reflected activity of inferior collicular neurones, while the fast component (N(4)) with a 3 msec peak latency represented activity of ascending lateral lemniscal fibres. PMID:5387030

Suga, N

1969-08-01

260

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

PubMed Central

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

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

2014-01-01

261

HYPOTHERMIA AND CHLOROPENT ANESTHESIA DIFFERENTIALLY AFFECT THE FLASH EVOKED POTENTIALS OF HOODED RATS  

EPA Science Inventory

Anesthetics and body temperature alterations are both known to alter parameters of sensory-evoked responses. However few studies have quantitatively assessed the contributions of hypothermia to anesthetic-induced changes. Two experiments were performed. In the first, chronically ...

262

Somatosensory evoked potentials in Hallervorden-Spatz-neuroaxonal-dystrophy complex with dorsal column involvement.  

PubMed

Two patients with a marked hypointensity of the globus pallidus on magnetic resonance imaging (MRI), which is known to be diagnostic for Hallervorden-Spatz disease (HSD), are presented. Patient 1 fell ill at about 10 years of age with visual disturbance, spastic paraplegia and mild ataxia, while patient 2 was affected during the second year of life with clinical features compatible with infantile neuroaxonal dystrophy (INAD). The two patients had certain clinical features in common; upper and lower motor neuron involvement, visual disturbance secondary to optic nerve atrophy, and dorsal column dysfunction, the evidence of which was seen from abnormal somatosensory evoked potentials (SEPs) obtained after posterior tibial nerve stimulation. In both patients, electron microscopic examination of the biopsied skin or sural nerve showed dystrophic axons, spheroids, and involvement of the peripheral nerve was indicated. Sharing of these clinical, pathological and MRI characteristics by the two patients supports the view of Seitelberger, who regarded HSD and INAD as constituents of a single disease entity, therefore the two patients were described as belonging to a disease spectrum of "Hallervorden-Spatz-neuroaxonal-dystrophy complex (HS-ND)." Sensory impairment has been a rare clinical feature in "HS-ND" complex, although its existence is not inconceivable considering the usual affection of the dorsal column/lemniscal pathway with spheroids. SEP was considered very useful in disclosing this often unmanifested sensory disturbance in "HS-ND" complex. PMID:2335040

Mutoh, K; Okuno, T; Ito, M; Mikawa, H

1990-04-01

263

Visual evoked potentials to change in coloration of a moving bar  

PubMed Central

In our previous study we found that it takes less time to detect coloration change in a moving object compared to coloration change in a stationary one (Kreegipuu etal., 2006). Here, we replicated the experiment, but in addition to reaction times (RTs) we measured visual evoked potentials (VEPs), to see whether this effect of motion is revealed at the cortical level of information processing. We asked our subjects to detect changes in coloration of stationary (0°/s) and moving bars (4.4 and 17.6°/s). Psychophysical results replicate the findings from the previous study showing decreased RTs to coloration changes with increase of velocity of the color changing stimulus. The effect of velocity on VEPs was opposite to the one found on RTs. Except for component N1, the amplitudes of VEPs elicited by the coloration change of faster moving objects were reduced than those elicited by the coloration change of slower moving or stationary objects. The only significant effect of velocity on latency of peaks was found for P2 in frontal region. The results are discussed in the light of change-to-change interval and the two methods reflecting different processing mechanisms. PMID:24478683

Murd, Carolina; Kreegipuu, Kairi; Kuldkepp, Nele; Raidvee, Aire; Tamm, Maria; Allik, Juri

2014-01-01

264

Prognostic value of facial nerve antidromic evoked potentials in bell palsy: a preliminary study.  

PubMed

To analyze the value of facial nerve antidromic evoked potentials (FNAEPs) in predicting recovery from Bell palsy. Study Design. Retrospective study using electrodiagnostic data and medical chart review. Methods. A series of 46 patients with unilateral Bell palsy treated were included. According to taste test, 26 cases were associated with taste disorder (Group 1) and 20 cases were not (Group 2). Facial function was established clinically by the Stennert system after monthly follow-up. The result was evaluated with clinical recovery rate (CRR) and FNAEP. FNAEPs were recorded at the posterior wall of the external auditory meatus of both sides. Results. Mean CRR of Group 1 and Group 2 was 61.63% and 75.50%. We discovered a statistical difference between two groups and also in the amplitude difference (AD) of FNAEP. Mean ± SD of AD was -6.96% ± 12.66% in patients with excellent result, -27.67% ± 27.70% with good result, and -66.05% ± 31.76% with poor result. Conclusions. FNAEP should be monitored in patients with intratemporal facial palsy at the early stage. FNAEP at posterior wall of external auditory meatus was sensitive to detect signs of taste disorder. There was close relativity between FNAEPs and facial nerve recovery. PMID:22164176

Wenhao, Zhang; Minjie, Chen; Chi, Yang; Weijie, Zhang

2012-01-01

265

Behavioral and auditory evoked potential audiograms of a false killer whale (Pseudorca crassidens)  

NASA Astrophysics Data System (ADS)

Behavioral and auditory evoked potential (AEP) audiograms of a false killer whale were measured using the same subject and experimental conditions. The objective was to compare and assess the correspondence of auditory thresholds collected by behavioral and electrophysiological techniques. Behavioral audiograms used 3-s pure-tone stimuli from 4 to 45 kHz, and were conducted with a go/no-go modified staircase procedure. AEP audiograms used 20-ms sinusoidally amplitude-modulated tone bursts from 4 to 45 kHz, and the electrophysiological responses were received through gold disc electrodes in rubber suction cups. The behavioral data were reliable and repeatable, with the region of best sensitivity between 16 and 24 kHz and peak sensitivity at 20 kHz. The AEP audiograms produced thresholds that were also consistent over time, with range of best sensitivity from 16 to 22.5 kHz and peak sensitivity at 22.5 kHz. Behavioral thresholds were always lower than AEP thresholds. However, AEP audiograms were completed in a shorter amount of time with minimum participation from the animal. These data indicated that behavioral and AEP techniques can be used successfully and interchangeably to measure cetacean hearing sensitivity.

Yuen, Michelle M. L.; Nachtigall, Paul E.; Breese, Marlee; Supin, Alexander Ya.

2005-10-01

266

Investigating the temporal dynamics of dolphin biosonar using phantom echoes and auditory evoked potentials.  

PubMed

Phantom echo generation replaces physical targets with electronic signals that can be delayed in time, scaled in amplitude, and broadcast to an echolocating animal to simulate echoes from distant objects. Compared to physical targets, phantom echoes have the advantages of allowing for instantaneous changes in target characteristics, independent manipulation of echo delay and echo amplitude, and easy randomization of target range. At the Navy Marine Mammal Program in San Diego, California, phantom echo generation is combined with measurements of auditory evoked potentials to investigate the temporal dynamics of biosonar signal emission and reception in bottlenose dolphins. The studies are primarily focused on examining automatic gain control mechanisms by measuring changes in hearing sensitivity - assessed via the auditory steady-state response (ASSR) to an amplitude modulated tone - over time courses corresponding to single biosonar click-echo pairs. Results show the ASSR amplitude initially decreases at the time of click emission and then recovers following click emission, with the time course of recovery related to target range, click amplitude, and tone frequency. Additional studies are focused on dynamic changes in click emissions that occur with changes in target range. [Work funded by SSC Pacific Naval Innovative Science and Engineering (NISE) program.]. PMID:25235125

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

2014-04-01

267

Association analysis for serotonin transporter promoter polymorphism and auditory evoked potentials for major depression.  

PubMed

The serotonergic system has been implicated in the production of the N1 and P2 components of auditory evoked potentials (AEPs). Moreover, studies have indicated the influence of heritability in the genesis of these AEP components. The serotonin transporter is the major site of serotonin reuptake into the presynaptic neuron, and it has been determined that variants in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) may affect gene transcription activity. The present study tested the hypothesis that the 5-HTTLPR genetic polymorphism is associated with the N1 and P2 components of AEPs in a sample of 127 Chinese patients (mean age: 41.6 years; male/female ratio: 58/69) diagnosed with major depression. Analysis of the results revealed a significantly shorter P2 latency for patients bearing the s/s genotype in comparison with l allele carriers, especially for the female patients (p = 0.004). The 5-HTTLPR polymorphism accounted for 3.4% of the variance in P2 latency. Our findings suggest a relationship between the 5-HTTLPR polymorphism and AEP P2 latency, and further studies of other genetic polymorphisms in the serotonergic system may help to predict this latency. PMID:12378120

Chen, Tai-Jui; Yu, Y W-Y; Chen, Ming-Chao; Tsai, Shih-Jen; Hong, Chen-Jee

2002-01-01

268

Comparison of Visual Evoked Potentials and Retinal Nerve Fiber Layer Thickness in Alzheimer's Disease  

PubMed Central

Introduction: Alzheimer’s disease (AD) is a long term progressive neurodegenerative disease and might affect the retinal nerve fiber layer thickness (RNFLT) of the eye. There is increasing evidence that visual evoked potentials (VEP), which are an objective way to indicate visual field loss, might be affected by the disease as well. Materials and Methods: About 22 patients (mean age: 75.9?±?6.1?years; 14 women) with mild-to-moderate AD and 22 sex-matched healthy patients were examined. We compared the use of VEP and RNFLT using the latest high-resolution spectral domain optical coherence tomography with eye-tracking capabilities for optimized peripapillary scan centering for the first time in AD patients. Results: The mean MMSE score was 22.59?±?5.47 in the AD group, and did not significantly correlate with the VEP latencies. We found no significant difference between the VEP latencies of the AD patients and those of the control patients. No peripapillary sector of the retina had a RNFLT significantly correlated with the VEP latencies. Discussion: We demonstrated that pattern VEP did not show any significant correlation despite subtle loss in RNFLT. It remains open whether additional flash VEP combined with RNFLT analysis may be useful in diagnosing AD, particularly for mild-to-moderate stages of the disease. PMID:24379800

Kromer, Robert; Serbecic, Nermin; Hausner, Lucrezia; Froelich, Lutz; Beutelspacher, Sven C.

2013-01-01

269

Electrically evoked compound action potential artifact rejection by independent component analysis: Technique validation?  

PubMed Central

The electrically-evoked compound action potential (ECAP) is the synchronous whole auditory nerve activity in response to an electrical stimulus, and can be recorded in situ on cochlear implant (CI) electrodes. A novel procedure (ECAP-ICA) to isolate the ECAP from the stimulation artifact, based on independent component analysis (ICA), is described here. ECAPs with artifact (raw-ECAPs) were sequentially recorded for the same stimulus on 9 different intracochlear recording electrodes. The raw-ECAPs were fed to ICA, which separated them into independent sources. Restricting the ICA projection to 4 independent components did not induce under-fitting and was found to explain most of the raw-data variance. The sources were identified and only the source corresponding to the neural response was retained for artifact-free ECAP reconstruction. The validity of the ECAP-ICA procedure was supported as follows: N1 and P1 peaks occurred at usual latencies; and ECAP-ICA and artifact amplitude-growth functions (AGFs) had different slopes. Concatenation of raw-ECAPs from multiple stimulus currents, including some below the ECAP-ICA threshold, improved the source separation process. The main advantage of ECAP-ICA is that use of maskers or alternating polarity stimulation are not needed. PMID:23632279

Akhoun, Idrick; McKay, Colette M.; El-Deredy, Wael

2013-01-01

270

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

PubMed

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

Kent, Alexander R; Grill, Warren M

2011-01-01

271

Electrically evoked compound action potential artifact rejection by independent component analysis: technique validation.  

PubMed

The electrically-evoked compound action potential (ECAP) is the synchronous whole auditory nerve activity in response to an electrical stimulus, and can be recorded in situ on cochlear implant (CI) electrodes. A novel procedure (ECAP-ICA) to isolate the ECAP from the stimulation artifact, based on independent component analysis (ICA), is described here. ECAPs with artifact (raw-ECAPs) were sequentially recorded for the same stimulus on 9 different intracochlear recording electrodes. The raw-ECAPs were fed to ICA, which separated them into independent sources. Restricting the ICA projection to 4 independent components did not induce under-fitting and was found to explain most of the raw-data variance. The sources were identified and only the source corresponding to the neural response was retained for artifact-free ECAP reconstruction. The validity of the ECAP-ICA procedure was supported as follows: N1 and P1 peaks occurred at usual latencies; and ECAP-ICA and artifact amplitude-growth functions (AGFs) had different slopes. Concatenation of raw-ECAPs from multiple stimulus currents, including some below the ECAP-ICA threshold, improved the source separation process. The main advantage of ECAP-ICA is that use of maskers or alternating polarity stimulation are not needed. PMID:23632279

Akhoun, Idrick; McKay, Colette M; El-Deredy, Wael

2013-08-01

272

Instrumentation to Record Evoked Potentials for Closed-Loop Control of Deep Brain Stimulation  

PubMed Central

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

Kent, Alexander R.; Grill, Warren M.

2012-01-01

273

Visual evoked potentials to change in coloration of a moving bar.  

PubMed

In our previous study we found that it takes less time to detect coloration change in a moving object compared to coloration change in a stationary one (Kreegipuu etal., 2006). Here, we replicated the experiment, but in addition to reaction times (RTs) we measured visual evoked potentials (VEPs), to see whether this effect of motion is revealed at the cortical level of information processing. We asked our subjects to detect changes in coloration of stationary (0(°)/s) and moving bars (4.4 and 17.6(°)/s). Psychophysical results replicate the findings from the previous study showing decreased RTs to coloration changes with increase of velocity of the color changing stimulus. The effect of velocity on VEPs was opposite to the one found on RTs. Except for component N1, the amplitudes of VEPs elicited by the coloration change of faster moving objects were reduced than those elicited by the coloration change of slower moving or stationary objects. The only significant effect of velocity on latency of peaks was found for P2 in frontal region. The results are discussed in the light of change-to-change interval and the two methods reflecting different processing mechanisms. PMID:24478683

Murd, Carolina; Kreegipuu, Kairi; Kuldkepp, Nele; Raidvee, Aire; Tamm, Maria; Allik, Jüri

2014-01-01

274

Motor evoked potentials in clinically isolated syndrome suggestive of multiple sclerosis.  

PubMed

The aim of the present study was to determine the sensitivity and the profile of motor evoked potentials (MEP) in patients with clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS). We measured the central motor conduction time (CMCT), amplitude ratio (AR), and surface ratio (SR) in tibialis anterior and first dorsal interosseous muscles in 22 patients with CIS. In 12 patients, the triple stimulation technique (TST) was also performed. AR was abnormal in 50% of patients, CMCT in 18% of patients, and TST in 25% of patients. AR had the highest sub-clinical sensitivity and the best positive predictive value. In the absence of clinical pyramidal signs, an early AR decrease seems to result from demyelination inducing excessive temporal dispersion of the MEP, while in territories with clinical pyramidal signs, it seems to result from conduction failure, which suggests that clinical pyramidal signs may be attributable to conduction failure. This study demonstrates that MEP, especially the AR, is sensitive to motor pathway dysfunction right from the early stages of MS. PMID:19153175

Rico, A; Audoin, B; Franques, J; Eusebio, A; Reuter, F; Malikova, I; Ali Cherif, A; Pouget, J; Pelletier, J; Attarian, S

2009-03-01

275

Hypohydration and muscular fatigue of the thumb alter median nerve somatosensory evoked potentials.  

PubMed

The mechanisms by which dehydration impairs endurance performance remain unresolved but may involve alterations in afferent neural processing. The purpose of this study was to determine the effect of hypohydration on somatosensory evoked potentials (SEPs) at rest and during recovery from fatiguing exercise. Fourteen volunteers (12 men, 2 women) performed repetitive isometric thumb contractions (50% maximal voluntary contractions (MVC) and 100% MVC in a 5:1 ratio, each contraction separated by 5 s of rest) until exhaustion when euhydrated (EU) and when hypohydrated by 4% body mass (HY). SEPs were obtained from the median nerve. The results indicated that HY did not produce statistical differences in time to exhaustion (EU=754 (SD 255); HY=714 (SD 318) s; p=0.66) or rate of muscle fatigue. However, HY was associated with greater subjective feelings of fatigue and loss of vigor after exhaustive exercise (p<0.01). HY affected N20 latency with an interaction effect of hydration by fatigue state (EU-Rest: 18.5 (SD 1.6) ms; EU-Fatigue: 19.0 (SD 1.6) ms; HY-Rest: 18.3 (SD 1.3) ms; HY-Fatigue: 18.4 (SD 1.5) ms; p=0.034), but N20 and N20-P22 amplitude responses were similar between HY and EU trials. We concluded that moderate water deficits appear to alter afferent signal processing within the cerebral cortex. PMID:20725111

Montain, Scott J; Tharion, William J

2010-08-01

276

Comparing the Efficacy of Excitatory Transcranial Stimulation Methods Measuring Motor Evoked Potentials  

PubMed Central

The common aim of transcranial stimulation methods is the induction or alterations of cortical excitability in a controlled way. Significant effects of each individual stimulation method have been published; however, conclusive direct comparisons of many of these methods are rare. The aim of the present study was to compare the efficacy of three widely applied stimulation methods inducing excitability enhancement in the motor cortex: 1?mA anodal transcranial direct current stimulation (atDCS), intermittent theta burst stimulation (iTBS), and 1?mA transcranial random noise stimulation (tRNS) within one subject group. The effect of each stimulation condition was quantified by evaluating motor-evoked-potential amplitudes (MEPs) in a fixed time sequence after stimulation. The analyses confirmed a significant enhancement of the M1 excitability caused by all three types of active stimulations compared to sham stimulation. There was no significant difference between the types of active stimulations, although the time course of the excitatory effects slightly differed. Among the stimulation methods, tRNS resulted in the strongest and atDCS significantly longest MEP increase compared to sham. Different time courses of the applied stimulation methods suggest different underlying mechanisms of action. Better understanding may be useful for better targeting of different transcranial stimulation techniques. PMID:24804104

Fritzsche, Georg

2014-01-01

277

Sensitivity and specificity of somatosensory and neurogenic-motor evoked potentials in animals and humans.  

PubMed

The purpose of this study was to report the effects of spinal cord compression, ischemia, and distraction on clinical status, and somatosensory (SEP) and neurogenic-motor evoked potentials (NMEPs) in animals. The authors also reported their clinical experience with NMEPs elicited from humans undergoing surgery for spinal deformities. Results from the animal studies indicate that NMEPs are more sensitive and specific to the effects from spinal cord compression, ischemia, and distraction than SEPs. In every situation, NMEPs always correlated with the animal's post-surgical clinical status, while SEPs demonstrated an unacceptable false positive and false negative rate. In the 111 clinical cases in which NMEPs were administered, reliable NMEPs were easily elicited in more than 90% of the cases. In the remaining cases, no reliable NMEPs could be recorded because of procedural errors, which have been resolved. The results from this study suggest that the use of NMEPs should be considered as an adjunct to SEPs when monitoring spinal cord function during surgery. PMID:3061024

Owen, J H; Laschinger, J; Bridwell, K; Shimon, S; Nielsen, C; Dunlap, J; Kain, C

1988-10-01

278

The effect of nerve root lesioning on various somatosensory evoked potentials in the hog.  

PubMed

Somatosensory evoked potentials (SEPs) were recorded at the lumbar spine following stimulation of the tibial nerve (mixed-nerve SEP; MSEP), the sural nerve (specific nerve SEP; SSEP), and the skin corresponding to the L6 and S1 dermatomes (dermatomal field SEP; DSEP-L and DSEP-S) in the hog. To determine the sensitivity of these three SEPs to the single nerve root (S1 root) function, the effects of nerve roots lesioning were investigated. Cutting S1 nerve root reduced the peak-to-peak amplitude of MSEP by only 28% in comparison with baseline values. The relative amplitudes of SSEP, DSEP-L, and DSEP-S were decreased by 46%, 11% and 51%, respectively. When S1 nerve root was left intact and L5, L6, and S2 nerve roots were cut, the relative amplitudes of MSEP, SSEP, DSEP-L, and DSEP-S were decreased to 68%, 73%, 31%, and 74%, respectively. These results indicate that DSEP-S is as sensitive to the function of S1 nerve root as SSEP but the sensitivities of DSEP-S and SSEP are low in the hog. MSEP is shown unsuitable to monitor the single nerve root dysfunction. PMID:8367778

Terada, K; Larson, B J; Owen, J H; Sugioka, Y

1993-06-15

279

Topiramate modulates habituation in migraine: evidences from nociceptive responses elicited by laser evoked potentials  

PubMed Central

Background Lack of habituation during repetitive stimulation is the most consistent interictal abnormality of cortical information processing observed in migraine. Preventive migraine treatments might act by stabilizing cortical excitability level and thus the habituation to external stimuli. Methods We examined the effects of preventive treatment with topiramate on migraineur’s habituation to nociceptive stimulation. Scalp potentials were evoked by Nd-YAP Laser stimulation of the hand dorsum and supraorbital region in 13 patients with migraine without aura (MO) and 15 healthy volunteers (HV). The exam was repeated in MO before and after treatment. Results We observed a lack of habituation and lower initial amplitudes in MO compared to HV. These abnormalities reached statistical significance for N1 LEPs component, generated in the secondary somatosensory cortex (SII), but not for N2/P2 complex, generated in the insula and anterior cingulated cortex (ACC). Topiramate normalized the N1 habituation pattern in MO, with a significant correlation between clinical effects and normalization of neurophysiological responses. Conclusions Our results indicate a modulating action of topiramate on cortical processing of sensorial stimuli, mainly regarding the sensory-discriminative component of pain, elaborated by SII, without a significant effect on the affective dimension of pain, in which the ACC has an important role. PMID:23566208

2013-01-01

280

Short- and long-term modulation of upper limb motor-evoked potentials induced by acupuncture.  

PubMed

The aim of this study was to investigate in humans the effects of acupuncture upon upper-limb motor-evoked potentials (MEPs), elicited by transcranial magnetic stimulation of the primary motor cortex. It is known that peripheral sensory stimulation can be used to induce short- and long-term changes in motor cortex excitability. Data show that the simple insertion of the needle is an adequate somatosensory stimulus to induce a significant modulation of MEP amplitude, the sign of which (facilitation or inhibition) is specific to the investigated muscle and to the point of needle insertion. Moreover, MEP changes in upper-limb muscles are also observed following needling of lower-limb sites, revealing the presence of long-distance effects of acupuncture. Finally, the modulation in muscle excitability considerably outlasts the time period of needle application, demonstrating the induction of long-term plastic changes in the central nervous system. In addition, results have shown that the effects on muscle excitability are not restricted to the stimulation of well-coded acupoints, as described in traditional Chinese medicine, but they can also be induced by needling of nonacupoints, normally not used for therapeutic purposes. The possible neuronal mechanisms underlying the observed effects of acupuncture are discussed in relation to the available neurophysiological data regarding the interlimb reflexes and the changes in the representational cortical maps induced in humans by a prolonged somatosensory stimulation. PMID:16623849

Maioli, Claudio; Falciati, Luca; Marangon, Mattia; Perini, Sergio; Losio, Antonio

2006-04-01

281

The effects of propofol on rat transcranial magnetic motor evoked potentials.  

PubMed

INTRAOPERATIVE MONITORING OF motor evoked potentials (MEPs) may become a valuable test of spinal cord function during surgery. Unfortunately, MEP responses are affected by most common anesthetics. We studied the effect of intravenous propofol on transcranial magnetic MEPs (tcMMEPs) in the rat. Baseline tcMMEPs were recorded before administration of the drug. Each rat then received three induction doses of propofol, 10, 5, and 5 mg/kg (totaling 10, 15, and 20 mg/kg) and three successive 20-minute infusion doses at rates of 10, 20, and 40 mg/kg/h, respectively. An MEP intensity series was performed after each induction dose, during each infusion, and during a 20-minute recovery period. tcMMEPs recorded during the induction period demonstrated a significant, dose-dependent increase in onset latency and a marked decrease in amplitude. Infusion tcMMEPs displayed increased onset latencies but demonstrated a significant change in amplitudes only after the largest infusion dose. The MEPs approached baseline levels after discontinuation of the propofol. This study demonstrates that tcMMEPs can be successfully recorded from the rat during propofol anesthesia. PMID:8559347

Fishback, A S; Shields, C B; Linden, R D; Zhang, Y P; Burke, D

1995-11-01

282

Intraoperative Monitoring of Motor-Evoked Potentials for Supratentorial Tumor Surgery  

PubMed Central

Objective The purpose of this study was to assess the feasibility and clinical efficacy of motor evoked potential (MEP) monitoring for supratentorial tumor surgery. Methods Between 2010 and 2012, to prevent postoperative motor deterioration, MEP recording after transcranial stimulation was performed in 84 patients with supratentorial brain tumors (45 males, 39 females; age range, 24-80 years; median age, 58 years). MEP monitoring results were correlated with postoperative motor outcome compared to preoperative motor status. Results MEP recordings were stable in amplitude (<50% reduction in amplitude) during surgery in 77 patients (91.7%). No postoperative motor deficit was found in 66 out of 77 patients with stable MEP amplitudes. However, postoperative paresis developed in 11 patients. False negative findings were associated with edema in peri-resectional regions and postoperative bleeding in the tumor bed. MEP decrease in amplitude (>50%) occurred in seven patients (8.3%). However, no deficit occurred postoperatively in four patients following preventive management during the operation. Three patients had permanent paresis, which could have been associated with vascular injury during tumor resection. Conclusions MEP monitoring during supratentorial tumor surgery is feasible and safe. However, false negative MEP results associated with postoperative events may occur in some patients. To achieve successful monitoring, collaboration between surgeon, anesthesiologist and an experienced technician is mandatory. PMID:25328645

Lee, Jung Jae; Kim, Young Il; Hong, Jae Taek; Sung, Jae Hoon; Lee, Sang Won

2014-01-01

283

Dose-dependent effect of nutritional sulfite intake on visual evoked potentials and lipid peroxidation.  

PubMed

The aim of this study was to clarify the dose-dependent effect of sulfite (SO?˛?) ingestion on brain and retina by means of electrophysiological and biochemical parameters. Fifty two male Wistar rats, aged 3 months, were randomized into four experimental groups of 13 rats as follows; control (C), sulfite treated groups (S(1); 10 mg/kg/day, S?; 100mg/kg/day, S?; 260 mg/kg/day). Control rats were administered distilled water, while the other three groups were given sodium metabisulfite (Na?S?O?) of amounts mentioned above, via gavage for a period of 35 days. All components of visual evoked potential (VEP) were prolonged in S? and S? groups compared with S? and C groups. Plasma-S-sulfonate levels, which are an indicator of sulfur dioxide (SO?) exposure, were increased in Na?S?O? treated groups in a dose-dependent manner. Furthermore, the significant increments in thiobarbituric acid reactive substances (TBARS) and 4-hydroxy-2-nonenal (4-HNE) levels occurred with increasing intake of Na?S?O?. Though not significant, glutathione (GSH) and oxidized glutathione (GSSG) levels were observed to decrease with increasing doses of Na?S?O?. In conclusion, Na?S?O? treatment in rats caused a dose-dependent increase in lipid peroxidation and all VEP latencies. The data indicate that lipid peroxidation could play an important role in sulfite toxicity. PMID:20875852

Ozturk, Nihal; Yargicoglu, Piraye; Derin, Narin; Akpinar, Deniz; Agar, Aysel; Aslan, Mutay

2011-01-01

284

The effect of sodium metabisulfite on visual evoked potentials in rats with hypercholesterolemia.  

PubMed

This study aimed to investigate the effects of hypercholesterolemia on visual evoked potentials (VEPs) and sulfite additional effects. Rats were assigned as follows: control (C), sulfite (S), hypercholesterolemia (H), vitamin E (E), sulfite + vitamin E (SE), hypercholesterolemia + sulfite (HS), hypercholesterolemia + vitamin E (HE), and hypercholesterolemia + sulfite + vitamin E (HSE). Hypercholesterolemic diet led significant increase in plasma cholesterol levels of rats. Brain thiobarbituric acid reactive substances (TBARS) levels were significantly increased in S, E, SE, HE and HSE groups compared with C. TBARS levels were increased in HE and HSE groups as compared to HS group. Nitrite levels were decreased in S, SE, H, HS and HSE groups compared with C. Nitrite level was notably increased in the HE group compared with H group. Sulfite exposure prolonged N1 and P3 latencies of VEP in group S compared with C. Prolonged VEP latencies by sulfite were significantly decreased by vitamin E in SE group. Cholesterol rich diet increased VEP latencies in comparison with control latencies. Sulfite gave rise to an additional increase in P3 latency in HS group compared with H group. Vitamin E-treated animals had notably shortened latencies of VEP components in HE and HSE groups according to the H and HS groups, respectively. PMID:21463131

Savcioglu, Feyza; Ozsoy, Ozlem; Hacioglu, Gulay; Kucukatay, Vural; Yargicoglu, Piraye; Agar, Aysel

2011-07-01

285

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

PubMed Central

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

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

2013-01-01

286

Profiles in fibromyalgia: algometry, auditory evoked potentials and clinical characterization of different subtypes.  

PubMed

The heterogeneity found in fibromyalgia (FM) patients has led to the investigation of disease subgroups, mainly based on clinical features. The aim of this study was to test the hypothesis that clinical FM subgroups are associated with different underlying pathophysiological mechanisms. Sixty-three FM patients were classified in type I or type II, according to the Fibromyalgia Impact Questionnaire (FIQ), and in mild/moderate versus severe FM, according to the severity of three cardinal symptoms considered in the American College of Rheumatology (ACR) 2010 criteria (unrefreshed sleep, cognitive problems and fatigue). To validate the subgroups obtained by these two classifications, we calculated the area under the receiver operating characteristic curves for various clinical variables and for two potential biomarkers of FM: Response to experimental pressure pain (algometry) and the amplitude/intensity slopes of the auditory evoked potentials (AEPs) obtained to stimuli of increasing intensity. The variables that best discriminated type I versus type II were those related to depression, while the indices of clinical or experimental pain (threshold or tolerance) did not significantly differ between them. The variables that best discriminated the mild/moderate versus severe subgroups were those related to the algometry. The AEPs did not allow discrimination among the generated subsets. The FIQ-based classification allows the identification of subgroups that differ in psychological distress, while the index based on the ACR 2010 criteria seems to be useful to characterize the severity of FM mainly based on hyperalgesia. The incorporation of potential biomarkers to generate or validate classification criteria is crucial to advance in the knowledge of FM and in the understanding of pathophysiological pathways. PMID:24723098

Trińanes, Yolanda; González-Villar, Alberto; Gómez-Perretta, Claudio; Carrillo-de-la-Peńa, María T

2014-11-01

287

Sham TMS: intracerebral measurement of the induced electrical field and the induction of motor-evoked potentials  

Microsoft Academic Search

%Testing the therapeutic potential of transcranial magnetic stimulation (TMS) in controlled trials requires a valid sham condition. Sham TMS is typically administered by tilting the coil 45–90° off the scalp, with one or two wings of the coil touching the scalp. Lack of cortical effects has not been verified. mWe compared sham manipulations in their thresholds for eliciting motor-evoked potentials

Sarah H. Lisanby; David Gutman; Bruce Luber; Charles Schroeder; Harold A. Sackeim

2001-01-01

288

[The diagnostic significance of auditory evoked brain stem potentials in multiple sclerosis].  

PubMed

30 patients suffering from multiple sclerosis were examined by BERA among other audiological tests. In 47% we stated significant pathological BERA-latencies, in 53% pathological interpeak-intervals. The most patients have symptoms of brainstem, but 3 cases spinal symptoms. There are no constant correlations to subjective hearing threshold measurements. According to literature BERA, especially the measurement of interpeak-intervals, increases diagnostic security of the diagnosis multiple sclerosis. PMID:2704769

Fritsche, F; Templin, A; Knothe, J

1989-01-01

289

A report of two cases of lip and tongue bite injury associated with transcranial motor evoked potentials.  

PubMed

Transcranial electric motor evoked potentials (TCeMEPs) are routinely used intraoperatively to detect and prevent iatrogenic injury to the spinal cord, specifically the corticospinal tract. Complications related to TCeMEP testing include the potential for seizure induction, cardiac arrhythmia, scalp burns, infection, and tongue or lip laceration. Among this list of potential complications, tongue and lip lacerations are the most common and most directly attributable to transcranial stimulation. The technique of low voltage stimulation and the correct placement of oral bite blocks is successful in preventing patient bite injuries. We report two cases of patient bite injuries following TCeMEPs and discuss potential mechanisms of injury and prevention. PMID:21313791

Davis, Scott F; Kalarickal, Philip; Strickland, Ted

2010-12-01

290

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

PubMed Central

Transcranial magnetic stimulation (TMS) has often been used in conjunction with electroencephalography (EEG), which is effective for the direct demonstration of cortical reactivity and corticocortical connectivity during cognitive tasks through the spatio-temporal pattern of long-latency TMS-evoked potentials (TEPs). However, it remains unclear what pattern is associated with the inhibition of a planned motor response. Therefore, we performed TMS-EEG recording during a go/stop task, in which participants were instructed to click a computer mouse with a right index finger when an indicator that was moving with a constant velocity reached a target (go trial) or to avoid the click when the indicator randomly stopped just before it reached the target (stop trial). Single-pulse TMS to the left (contralateral) or right (ipsilateral) motor cortex was applied 500 ms before or just at the target time. TEPs related to motor execution and inhibition were obtained by subtractions between averaged EEG waveforms with and without TMS. As a result, in TEPs induced by both contralateral and ipsilateral TMS, small oscillations were followed by a prominent negative deflection around the TMS site peaking at approximately 100 ms post-TMS (N100), and a less pronounced later positive component (LPC) over the broad areas that was centered at the midline-central site in both go and stop trials. However, compared to the pattern in go and stop trials with TMS at 500 ms before the target time, N100 and LPC were differently modulated in the go and stop trials with TMS just at the target time. The amplitudes of both N100 and LPC decreased in go trials, while the amplitude of LPC decreased and the latency of LPC was delayed in both go and stop trials. These results suggested that TMS-induced neuronal reactions in the motor cortex and subsequent their propagation to surrounding cortical areas might change functionally according to task demand when executing and inhibiting a motor response. PMID:24282400

Kadota, Hiroshi; Nozaki, Daichi

2013-01-01

291

Color discrimination ellipses of trichromats measured with transient and steady state visual evoked potentials.  

PubMed

The purpose of this work is to investigate the use of different forms of visual evoked potentials (VEPs) to measure color discrimination thresholds and to plot color discrimination ellipses (MacAdam, 1942). Five normal trichromats (24.5 +/- 2.6 years-old) were monocularly tested. Stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions radiating from one reference point of the CIE 1976 chromaticity diagram (u' = 0.225; v' = 0.415). Heterochromatic flicker photometry (HFP) was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. VEPs were elicited using two cycles per degree grating stimuli at three different temporal configurations: transient, onset (300 ms)/offset (700 ms), 1 Hz fundamental frequency; steady-state, onset (50 ms)/offset (50 ms), 10 Hz fundamental frequency; and steady-state pattern reversal at 5 Hz fundamental frequency (10 Hz phase reversal). VEP amplitude was measured using transient VEP N1-P1 components and steady state VEP first (10 Hz) and second (20 Hz) harmonics. VEP amplitude was plotted as a function of chromatic distance in the CIE 1976 color space and the data points were extrapolated to zero amplitude level to obtain chromatic discrimination thresholds. The results were compared with psychophysical measurements performed using the same stimulus configurations and with the pseudoisochromatic method of Mollon-Reffin (one-way ANOVA). For all subjects and all stimulation methods, the ellipses showed small sizes, low ellipticities, and were vertically oriented. Despite some consistent differences in the results obtained with different procedures, there was no statistical difference between ellipses obtained electrophysiologically and psychophysically. For steady state VEPs, ellipses obtained from second harmonic amplitudes were larger and more elongated in the tritan direction than those obtained with first harmonic amplitudes. PMID:18598404

Gomes, Bruno D; Souza, Givago S; Lima, Monica G; Rodrigues, Anderson R; Saito, Cézar A; da Silva Filho, Manoel; Silveira, Luiz Carlos L

2008-01-01

292

The effects of prenatal exposure to buprenorphine or methadone on infant visual evoked potentials.  

PubMed

This study compared the neurological development of 4 month old infants exposed to buprenorphine or methadone during pregnancy to that of a control group of non-exposed infants. Participants were 30 buprenorphine-maintained women, 22 methadone-maintained women and 33 non opioid-dependent controls, and their infants. Women were enrolled during pregnancy as part of an open-label non-randomised flexible-dosing longitudinal study. Groups were matched for maternal age, parity, gravida, and tobacco and alcohol use. Infant neurological development was assessed by measuring latency of pattern reversal visual evoked potentials (VEP). One-way between groups analyses of variance (ANOVA) were conducted to test the statistical significance of differences between the mean latencies of the peak response to two different sized checkerboard patterns (48' and 69' of retinal arc). Infants prenatally exposed to methadone had significantly prolonged latencies, compared with infants in the control group and infants prenatally exposed to buprenorphine, in response to checks of 48' and 69'. VEP latencies of infants prenatally exposed to buprenorphine did not differ significantly from controls for either check size. After adjustment for covariates, prenatal exposure to methadone remained a significant predictor of VEP response to checks of 48', but not 69'. Maternal self-reported used of marijuana during pregnancy made a significant unique contribution to the variance in P1 latencies for both check sizes. Data from this controlled, non-randomised study suggest that buprenorphine may confer an advantage over methadone as a maintenance drug during pregnancy in terms of infant neural development at 4 months of age. PMID:19751825

Whitham, Justine N; Spurrier, Nicola J; Sawyer, Michael G; Baghurst, Peter A; Taplin, John E; White, Jason M; Gordon, Andrea L

2010-01-01

293

Contact heat-evoked potentials as a useful means in patients with Guillain-Barré syndrome.  

PubMed

Few objective methods have been utilized to identify the small myelinated fiber impairment causing neuropathic pain in Guillain-Barré syndrome (GBS). In this study, contact heat-evoked potentials (CHEPs) were applied to study the nociceptive pathway in GBS. Sixty GBS patients and fifty healthy controls were enrolled. The 60 GBS patients were divided into two subgroups presenting with or without subjective lower limb paresthesia (21/39). CHEPs were recorded at Cz and Pz with a peak thermal stimuli of 47 °C applied to the skin of the leg above the internal malleolus (AIM) and of the waist at the anterior superior iliac spine (ASIS) level. The N2 latency and N2-P2 amplitude of CHEPs were compared. When the skin of the leg AIM was stimulated, the N2 latency was significantly postponed (425.23 ± 28.66 vs. 402.30 ± 19.48 ms, P < 0.05) and the N2-P2 amplitude significantly decreased in GBS patients as compared to controls (32.71 ± 7.49 vs. 42.77 ± 8.71 ?V, P < 0.05). Slower nerve conduction velocity was observed in GBS patients (11.84 ± 1.45 vs. 13.28 ± 0.66 ms, P < 0.05). However, no differences in N2 latency or N2-P2 amplitude were detected between the two subgroups of GBS patients with or without subjective lower limb paresthesia (P all >0.05). Moreover, there were no differences in N2 latency and N2-P2 amplitude among different groups when the waist was stimulated at the ASIS level. Our study suggested that CHEPs could be utilized as an objective and non-invasive tool to detect small myelinated fiber damage in GBS patients, especially for those without subjective paresthesia. PMID:24584633

Zhang, Chao; Xie, Bingdi; Li, Xiaowen; Yao, Yuanrong

2014-08-01

294

Pattern-reversal visual-evoked potential in patients with occult macular dystrophy  

PubMed Central

Purpose: Occult macular dystrophy (OMD) is a hereditary retinal disease characterized by a normal fundus, normal full-field electroretinograms (ERGs), progressive decrease of visual acuity, and abnormal focal macular ERGs. The purpose of this study was to report pattern-reversal visual-evoked potential (pVEPs) findings in OMD patients. Patients and method: The pVEPs recorded from four patients with OMD (aged 42–61 years; 2 men and 2 women) were reviewed. The visual acuities ranged from 20/200 to 20/30. The amplitudes of the N-75 and P-100 (P2 amplitude) and the latency of the N-75 components (N1 latency) were analyzed. Results: The mean (±SD) P2 amplitude was 2.7 ± 1.9 ?V for the 5?, 4.8 ± 2.9 ?V for the 10?, 3.2 ± 2.1 ?V for the 20?, and 4.4 ± 3.5 ?V for the 40? checkerboard stimuli. The N1 latency was 122.2 ± 6.4 ms for the 5?, 105.0 ± 11.5 ms for the 10?, 97.7 ± 10.0 ms for the 20?, and 91.0 ± 13.7 ms for the 40? checkerboard stimuli. The mean P2 amplitude was reduced and the N1 latency was delayed in comparison with the laboratory standard for the Keio University Hospital. Conclusions: The delayed latency and reduced amplitude suggest a major contribution of the central cone pathway to the pVEPs. PMID:21191449

Hanazono, Gen; Ohde, Hisao; Shinoda, Kei; Tsunoda, Kazushige; Tsubota, Kazuo; Miyake, Yozo

2010-01-01

295

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

PubMed Central

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

Grossman, Emily D.; Srinivasan, Ramesh

2011-01-01

296

Impedance and electrically evoked compound action potential (ECAP) drop within 24 hours after cochlear implantation.  

PubMed

Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI) insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP) variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fifty-four subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (? 2.5 cm) and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p<0.001). There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes with long-term hearing/speech performance. PMID:23991008

Chen, Joshua Kuang-Chao; Chuang, Ann Yi-Chiun; Sprinzl, Georg Mathias; Tung, Tao-Hsin; Li, Lieber Po-Hung

2013-01-01

297

Impedance and Electrically Evoked Compound Action Potential (ECAP) Drop within 24 Hours after Cochlear Implantation  

PubMed Central

Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI) insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP) variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fifty-four subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (?2.5 cm) and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p<0.001). There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes with long-term hearing/speech performance. PMID:23991008

Chen, Joshua Kuang-Chao; Chuang, Ann Yi-Chiun; Sprinzl, Georg Mathias; Tung, Tao-Hsin; Li, Lieber Po-Hung

2013-01-01

298

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

PubMed

We used Motor Evoked Potentials (MEPs), elicited by transcranial magnetic stimulation, for assessing a motor pathways dysfunction in a selected group of Multiple Sclerosis (MS) patients, without limitation in walking. We selected 32 Relapsing Remitting MS patients, in remission phase, with EDSS < or = 3.5 and 20 healthy individuals with similar height and age distribution. We measured the following MEP parameters: motor thresholds; central motor conduction time (CMCT); amplitude and area, both expressed as MEP/CMAP ratio. Patients were divided into two groups according to the EDSS score: non-disabled group (ND; EDSS 0-1.5) and disabled group (D; EDSS 2-3.5). Mean average MEP values were significantly different in the patients compared with the controls. Even in MS patients with no or minor neurological signs (ND group), MEP parameters showed differences from controls and furthermore all MEP parameters were significantly different in the D group compared with the ND group. The 75% of the patients had an amplitude or area alteration; this percentage was significantly higher than the percentage of patients with a CMCT alteration (56.2%). In addition, CMCT increase was always associated with reduced amplitude and area, but amplitude and area alterations were present also in patients with normal CMCT. In early stages of MS, the higher percentage shown in alteration of MEP amplitudes and areas as opposed to CMCTs has not previously been highlighted in the literature. Independently of its pathogenesis (demyelination or axonal loss), the amplitude or area decrease should be considered in clinical trials and in follow-up studies, as a marker of the motor pathways dysfunction, at least as much as CMCT increase. PMID:17308868

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

2007-02-01

299

Laser-evoked potentials: prognostic relevance of pain pathway defects in patients with acute radiculopathy.  

PubMed

The radicular pain syndrome is a major problem in public health care that can lead to chronic back and leg pain in 30%. Ischalgia and back pain are the most prominent signs of dorsal root affection. Until now, no clinical or neurophysiological test procedure exists that evaluates the function of the dorsal root and predicts the prognosis of patients suffering from RPS. We have recently demonstrated that laser-evoked potentials (LEP) are able to demonstrate dorsal root damage. With this study, we investigated 54 patients with acute radicular symptoms and compared LEP parameters (side to side difference of latency and amplitude, transformed to a z-score) with their state of health after 3 months to calculate their predictive value for outcome prognosis. Most significantly, the latency difference between the LEP of the affected dermatome relative to the contralateral healthy dermatome was able to predict the prognosis. Latency z score above two demonstrates a 91% specificity (33% sensitivity) for a poor outcome at 3 months. A significant relation between amplitude changes and the main outcome measure could not be shown. Only extreme changes (z score >10) in amplitude show a high specificity for the persistence of ischialgia in particular (specificity 0.94; sensitivity 0.35). All other parameters, such as clinical scores or other LEP parameters, were not able to predict the outcome of patients. We propose that clinical testing using LEP with latency analysis is a useful tool for estimating the course of disease, so that patients with poor predictive parameters can be treated more invasively at early disease stages to avoid persistence of radiculopathy. PMID:19777272

Quante, Markus; Lorenz, Jürgen; Hauck, Michael

2010-02-01

300

Repetitive common peroneal nerve stimulation increases ankle dorsiflexor motor evoked potentials in incomplete spinal cord lesions.  

PubMed

Plasticity of corticospinal tract (CST) activity likely plays a key role in motor function recovery after central nervous system (CNS) lesions. In non-injured adults, 30 min of repetitive common peroneal nerve stimulation (rCPnS) increases CST excitability by 40-50% and the effect persists for at least 30 min. The present study evaluated with transcranial magnetic stimulation (TMS) the changes in CST excitability after 30 min of rCPnS in people with foot drop due to incomplete SCI. Suprathreshold rCPnS (25 Hz, alternating 1 s on 1 s off stimulation cycle) was given for two 15-min periods, while the subject sat at rest with ankle and knee joints fixed. Before, between, and after the periods of stimulation, the tibialis anterior (TA) motor evoked potentials (MEPs) to TMS were measured at a TMS intensity that originally produced a half-maximum MEP (typically 10-20% above threshold) while the sitting subject provided 25-30% maximum voluntary TA contraction. In 10 subjects with SCI, the peak-to-peak TA MEP increased by 14 ± 3% after rCPnS and the peak increase (+21 ± 7%) occurred 15 min after the cessation of rCPnS. The TA H-reflex, measured in separate experiments in 7 subjects, did not increase after rCPnS. The results indicate that rCPnS can increase CST excitability for the TA in people with incomplete SCI, although its effects appear smaller and shorter lasting than those found in non-injured control subjects. Such short-term plasticity in the CST excitability induced by rCPnS may contribute to long-term therapeutic effects of functional electrical stimulation previously reported in people with CNS lesions. PMID:21360230

Thompson, Aiko K; Lapallo, Brandon; Duffield, Michael; Abel, Briana M; Pomerantz, Ferne

2011-04-01

301

Sensory gating of auditory evoked potentials in rats: effects of repetitive stimulation and the interstimulus interval.  

PubMed

In the P50 gating or conditioning-testing (C-T) paradigm, the P50 response, a small positive midlatency ( approximately 50 ms after stimulus onset) component of the human auditory evoked potential (AEP), is reduced towards the second click (S2) as compared to the response to the first click (S1). This phenomenon is called sensory gating. The putative function of sensory gating is thought to protect subjects from being flooded by irrelevant stimuli. Comparative studies have been done in rats in order to elucidate the underlying neural substrate of sensory gating. However, for a direct comparison of rat and human AEP components, it is imperative for both components to show similar characteristics. The amount of sensory gating in humans is dependent on repetitive stimulation and the interstimulus interval (ISI). In the present study effects of repetitive stimulation (Experiment 1) and various ISIs (Experiment 2) were determined on rat AEP components. The results demonstrate that gating is not limited to a restricted cortical area or a single midlatency component and that repetitive stimulation and ISI affect gating of several rat AEP components. Components such as the vertex P17 and N22 show a decrease in gating within several S1-S2 presentations, mainly due to a decrease in amplitude to S1 (Experiment 1). Gating for vertex components (such as the P17, N22 and N50) is ISI dependent (Experiment 2), but there is no interval in the 200-600 ms range at which optimal gating occurs. The ISI effects on gating are due to an increase of the amplitude to S2. The results have implications for the discussion about the rat homologue of the human P50. PMID:11240214

de Bruin, N M; Ellenbroek, B A; van Schaijk, W J; Cools, A R; Coenen, A M; van Luijtelaar, E L

2001-02-01

302

Factors Affecting the Motor Evoked Potential Responsiveness and Parameters in Patients With Supratentorial Stroke  

PubMed Central

Objective To investigate the factors which affect the motor evoked potential (MEP) responsiveness and parameters and to find the correlation between the function of the upper extremities and the combined study of MEP with a diffusion tensor tractography (DTT) in patients with stroke. Methods A retrospective study design was used by analyzing medical records and neuroimaging data of 70 stroke patients who underwent a MEP test between June 2011 and March 2013. MEP parameters which were recorded from the abductor pollicis brevis muscle were the resting motor threshold, latency, amplitude, and their ratios. Functional variables, Brunnstrom stage of hand, upper extremity subscore of Fugl-Meyer assessment, Manual Function Test, and the Korean version of Modified Barthel Index (K-MBI) were collected together with the biographical and neurological data. The DTT parameters were fiber number, fractional anisotropy value and their ratios of affected corticospinal tract. The data were compared between two groups, built up according to the presence (MEP-P) or absence (MEP-N) of MEP on the affected hand. Results Functional and DTT variables were significantly different between MEP-P and MEP-N groups (p<0.001). Among the MEP-P group, the amplitude ratio (unaffected/affected) was significantly correlated with the Brunnstrom stage of hand (r=-0.427, p=0.013), K-MBI (r=-0.380, p=0.029) and the time post-onset (r=-0.401, p=0.021). The functional scores were significantly better when both MEP response and DTT were present and decreased if one or both of the two studies were absent. Conclusion This study indicates MEP responsiveness and amplitude ratio are significantly associated with the upper extremity function and the activities of daily living performance, and the combined study of MEP and DTT provides useful information. PMID:24639922

Choi, Tae Woong; Jang, Seung Gul; Yang, Seung Nam

2014-01-01

303

Extracting visual evoked potentials from EEG data recorded during fMRI-guided transcranial magnetic stimulation.  

PubMed

Transcranial Magnetic Stimulation (TMS) is an effective method for establishing a causal link between a cortical area and cognitive/neurophysiological effects. Specifically, by creating a transient interference with the normal activity of a target region and measuring changes in an electrophysiological signal, we can establish a causal link between the stimulated brain area or network and the electrophysiological signal that we record. If target brain areas are functionally defined with prior fMRI scan, TMS could be used to link the fMRI activations with evoked potentials recorded. However, conducting such experiments presents significant technical challenges given the high amplitude artifacts introduced into the EEG signal by the magnetic pulse, and the difficulty to successfully target areas that were functionally defined by fMRI. Here we describe a methodology for combining these three common tools: TMS, EEG, and fMRI. We explain how to guide the stimulator's coil to the desired target area using anatomical or functional MRI data, how to record EEG during concurrent TMS, how to design an ERP study suitable for EEG-TMS combination and how to extract reliable ERP from the recorded data. We will provide representative results from a previously published study, in which fMRI-guided TMS was used concurrently with EEG to show that the face-selective N1 and the body-selective N1 component of the ERP are associated with distinct neural networks in extrastriate cortex. This method allows us to combine the high spatial resolution of fMRI with the high temporal resolution of TMS and EEG and therefore obtain a comprehensive understanding of the neural basis of various cognitive processes. PMID:24893706

Sadeh, Boaz; Yovel, Galit

2014-01-01

304

Intraoperative continuous monitoring of facial motor evoked potentials in acoustic neuroma surgery.  

PubMed

The preservation of facial nerve function is one of the primary objectives in acoustic neuroma surgery. We detail our method of continuous intraoperative facial motor evoked potential (MEP) monitoring and present criteria for the preservation of facial nerve function to avoid postoperative facial nerve palsy. Our study population was comprised of 15 patients who did not (group 1), and 20 who did (group 2) undergo facial MEP monitoring during surgery to remove acoustic neuromas. In group 2, we continuously stimulated the facial motor cortex at 5- or 10-s intervals throughout surgery. Electromyograms (EMGs) were recorded from the contralateral orbicularis oculi- and orbicularis oris muscles. Optimal anode and cathode placement was at the facial motor cortex and the vertex, respectively. Postoperative facial palsy occurred in 8 of the 15 group 1 patients; in 2 it improved to grade II at 6 months after the operation. Of the 20 group 2 patients, 7 suffered postoperative facial palsy. At 6 months after the operation, their facial nerve function was normal. At the end of the operation, the ratio of the amplitude of the supramaximal EMG to the amplitude at the dural opening was 39.6 % in patients with- and 94.3 % in patients without transient postoperative facial palsy. Continuous facial MEP monitoring not only alerts to surgical invasion of the facial nerves but also helps to predict postoperative facial nerve function. To preserve a minimum amplitude ratio of 50 %, even transient postoperative facial palsy must be avoided. MEP monitoring is an additional useful modality for facial nerve monitoring during acoustic neuroma surgery. PMID:25015389

Tokimura, Hiroshi; Sugata, Sei; Yamahata, Hitoshi; Yunoue, Shunji; Hanaya, Ryosuke; Arita, Kazunori

2014-10-01

305

Difference of Diagnostic Rates and Analytical Methods in the Test Positions of Vestibular Evoked Myogenic Potentials  

PubMed Central

Objective To compare the differences of diagnostic rates, of the two widely used test positions, in measuring vestibular evoked myogenic potentials (VEMP) and selecting the most appropriate analytical method for diagnostic criteria for the patients with vertigo. Methods Thirty-two patients with vertigo were tested in two comparative testing positions: turning the head to the opposite side of the evaluating side and bowing while in seated position, and bowing while in supine positions. Abnormalities were determined by prolonged latency of p13 or n23, shortening of the interpeak latency, and absence of VEMP formation. Results Using the three criteria above for determining abnormalities, both the seated and supine positions showed no significant differences in diagnostic rates, however, the concordance correlation of the two positions was low. When using only the prolonged latency of p13 or n23 in the two positions, diagnostic rates were not significantly different and their concordance correlation was high. On the other hand, using only the shortened interpeak latency in both positions showed no significant difference of diagnostic rates, and the degree of agreement between two positions was low. Conclusion Bowing while in seated position with the head turned in the opposite direction to the area being evaluated is found to be the best VEMP test position due to the consistent level of sternocleidomastoid muscle tension and the high level of compliance. Also, among other diagnostic analysis methods, using prolonged latency of p13 or n23 as the criterion is found to be the most appropriate method of analysis for the VEMP test. PMID:24855617

Park, Jeong Mee; Yong, Sang Yeol; Kim, Jong Heon; Kim, Hee; Park, Sang-Yoo

2014-01-01

306

Relationship among level of distraction, evoked potentials, spinal cord ischemia and integrity, and clinical status in animals.  

PubMed

Somatosensory evoked potentials (SEPs) and neurogenic-motor evoked potentials (NMEPs) were recorded after overdistraction of the spinal cord at T5-T6, T12-L1, or L3-L4. Measures of spinal cord perfusion and clinical status were also administered. Results indicated that stiffer spinal segments allowed less distraction than more flexible segments. SEPs and NMEPs were lost quickly after overdistraction in stiff segments and slowly in more flexible segments. However, SEPs were less sensitive than NMEPs to effects from overdistraction. Spinal cord perfusion and integrity were consistent with reduced perfusion and structural damage after overdistraction in stiff segments; extremely reduced perfusion but no structural changes in more flexible segments. The application of these results to the clinical situation was provided. PMID:2259970

Owen, J H; Naito, M; Bridwell, K H

1990-09-01

307

Fisher syndrome or Bickerstaff brainstem encephalitis? Anti-GQ1b IgG antibody syndrome involving both the peripheral and central nervous systems.  

PubMed

We describe a 27-year-old woman who showed the clinical triad of Fisher syndrome (ophthalmoplegia, ataxia, and areflexia), a disturbance of consciousness, facial diplegia, and hemisensory loss. Her serum was positive for anti-GQ1b immunoglobulin G (IgG) antibody. The electroencephalographic findings (diffuse slow activity), median somatosensory evoked potential (absent cortical N20 with normal cervical N13), and blink reflex studies (absent R2) suggested central dysfunction, whereas results of facial nerve conduction studies (low amplitudes of compound muscle action potentials), F-wave and H-reflex studies (absent F-waves and soleus H-reflexes), and brainstem auditory evoked potentials (prolongation of wave I latency) suggested peripheral abnormalities. This case supports the hypothesized continuity between Fisher syndrome and Bickerstaff brainstem encephalitis. These two conditions may represent a single autoimmune disease mediated by anti-GQ1b antibody, usually involving the peripheral and occasionally the central nervous systems. PMID:12451613

Ogawara, Kazue; Kuwabara, Satoshi; Yuki, Nobuhiro

2002-12-01

308

Ketamine and phenobarbital do not reduce the evoked-potential enhancement induced by electroconvulsive shock seizures in the rat  

Microsoft Academic Search

Electroconvulsive shock (ECS) seizures provide an animal analog of electroconvulsive therapy (ECT). Repeated ECS seizures cause a long-lasting, and perhaps permanent, enhancement of entorhinal-dentate evoked potentials (EPs) in the rat. Recently it has been reported that ketamine protects against ECS-induced EP enhancement. The present study was designed to replicate these findings and to extend them by incorporating a phenobarbital group

Zoltan Gombos; Antonio Mendonça; Georgia A Cottrell; W McIntyre Burnham

1999-01-01

309

Somatosensory-evoked potentials indicate increased unpleasantness of noxious stimuli in response to increasing stimulus intensities in the rat  

Microsoft Academic Search

Recently, it has been shown in rats that specific characteristics of somatosensory-evoked potentials (SEPs) recorded from different sites on the scalp correlate differently to the amount of unpleasantness experienced by the animal following noxious stimulation. It was shown that the SEP recorded from vertex (Vx-SEP) did correlate with the unpleasantness, whereas the SEP recorded from the primary somatosensory cortex (SI-SEP)

Hugo van Oostrom; Peter J. Stienen; Ruud van den Bos; Harry N. M. de Groot; Ludo J. Hellebrekers

2007-01-01

310

Pattern shift visual evoked potentials in abstinent cocaine-dependent, alcohol-dependent, and cross-dependent patients  

Microsoft Academic Search

The present study evaluated pattern shift visual evoked potential (VEP) amplitudes and latencies in four groups of adult subjects, characterized by the presence\\/absence of a recent history of alcohol dependence factorially crossed with the presence\\/absence of a recent history of cocaine dependence. All of the subjects were healthy and uncomplicated by histories of serious head injury, seizures (including drug-related seizures),

Lance O. Bauer; Caroline Easton

1996-01-01

311

MRI of optic nerve and postchiasmal visual pathways and visual evoked potentials in secondary progressive multiple sclerosis  

Microsoft Academic Search

We studied the relationship between abnormalities shown by MRI and functional disturbances in the visual pathway as assessed\\u000a by the visual evoked potential (VEP) in 25 patients with established multiple sclerosis (MS); only 4 of whom had a history\\u000a of acute optic neuritis. Optic nerve MRI was abnormal in 19 (76 %) and is thus useful in detecting subclinical disease.

M. B. Davies; R. Williams; N. Haq; L. Pelosi; C. P. Hawkins

1998-01-01

312

Effects of Amoxapine and Imipramine on Evoked Potentials in the Continuous Performance Test in Patients with Affective Disorder  

Microsoft Academic Search

Twenty patients with major depressive disorder were studied with evoked potential (EP) topographic mapping after receiving placebo, imipramine, or amoxapine for 2 days in a random-assignment, double-blind design. Patients performed the Continuous Performance Test (CPT), a visual vigilance test. The stimuli were the digits 0–9, with 0 a target to be responded to with a button press. EPs were recorded

Monte S. Buchsbaum; Sunghoon Lee; Richard Haier; Joseph C. Wu; Mary Green; Wa Tang

1988-01-01

313

Effects of tethering on regional spinal cord blood flow and sensory-evoked potentials in growing cats  

Microsoft Academic Search

The spinal cords of 2-week-old kittens were tethered by fixing the end of the filum terminale to the lower sacrum, to study the effects of tethering and untethering on regional spinal cord blood flow (rSCBF), sensory-evoked potentials (SEPs) and clinical features. Progressive sensorimotor deficits and incontinence were observed in all the tethered cats. Cord tethering induced a reduction of rSCBF

Joon Ki Kang; Moon Chan Kim; Soo Kim; Jin Un Song

1987-01-01

314

Intraoperative monitoring of somatosensory-evoked potential in the spinal cord rectification operation by means of wavelet analysis  

NASA Astrophysics Data System (ADS)

Recently there has been a considerable interest in the use of a somatosensory evoked potential (SEP) for monitoring the functional integrity of the spinal cord during surgery such as spinal scoliosis. This paper describes a monitoring system and signal processing algorithms, which consists of 50 Hz mains filtering and a wavelet signal analyzer. Our system allows fast detection of changes in SEP peak latency, amplitude and signal waveform, which are the main parameters of interest during intra-operative procedures.

Liu, W.; Du, M. H.; Chan, Francis H. Y.; Lam, F. K.; Luk, D. K.; Hu, Y.; Fung, Kan S. M.; Qiu, W.

1998-09-01

315

Steady-state visual evoked potentials in the low frequency range in migraine: a study of habituation and variability phenomena  

Microsoft Academic Search

Previous studies have revealed that migraine patients display an increased photic driving to flash stimuli in the medium frequency range. The aim of this study was to perform a topographic analysis of steady-state visual evoked potentials (SVEPs) in the low frequency range (3–9 Hz), evaluating the temporal behaviour of the F1 amplitude by investigating habituation and variability phenomena. The main

Marina de Tommaso; Sebastiano Stramaglia; Jan Mathijs Schoffelen; Marco Guido; Giuseppe Libro; Luciana Losito; Vittorio Sciruicchio; Michele Sardaro; Mario Pellicoro; Franco Michele Puca

2003-01-01

316

Dermatomally stimulated somatosensory cerebral evoked potentials in the clinical diagnosis of lumbar disc disease.  

PubMed

Somatosensory evoked response--dermatomal (SER-D) is a new, apparently accurate method of diagnosis of lumbar nerve root compression. It is noninvasive and may be of subsequent value in choosing patients who are to be subjected to myelography in the future. PMID:6616890

Green, J; Gildemeister, R; Hazelwood, C

1983-07-01

317

Cholinergic Pairing with Visual Activation Results in Long-Term Enhancement of Visual Evoked Potentials  

E-print Network

Cholinergic Pairing with Visual Activation Results in Long-Term Enhancement of Visual Evoked´bec, Canada Abstract Acetylcholine (ACh) contributes to learning processes by modulating cortical plasticity) receptor antagonists before carbachol infusion. Stimulation of the cholinergic system paired with visual

318

Electrically evoked compound action potential measures for virtual channels versus physical electrodes  

PubMed Central

Objectives The number of distinct pitch percepts for cochlear implant (CI) listeners is somewhat limited by the number of physical electrodes in the array. Newer-generation CIs have the capability to potentially increase this number by stimulating areas of the cochlea between the physical electrodes. Currently this is achieved by electrically coupling adjacent electrodes or by simultaneously activating two electrodes with independent current sources (i.e., “current steering”). Presumably, either type of dual-electrode stimulation will generate neural excitation patterns that are intermediate to those generated by either physical electrode alone (henceforth termed virtual channel). However, it is not clear whether virtual-channel stimulation yields neural recruitment patterns with similar shapes and rates of growth as compared with each physical electrode alone. The purpose of this study was to compare basic electrically evoked compound action potential (ECAP) measures for physical electrodes and virtual channels to determine whether properties of the respective excitation patterns were similar. Design Data were collected for 12 adult CI recipients (N = 6 Nucleus Freedom CI24RE, N = 2 Advanced Bionics HiResolution 90K, N = 4 Advanced Bionics CII). ECAP responses were measured for a set of three adjacent physical electrodes and two corresponding intermediate virtual channels (e.g., physical electrodes 4, 5, and 6 and virtual channels 4+5 and 5+6) at three positions along the electrode array (basal, middle, and apical). Virtual channels for Nucleus subjects were produced via electrical coupling of adjacent electrode pairs (“dual-electrode mode”). For AB subjects, virtual channels were produced via simultaneous, in-phase stimulation of adjacent electrode pairs with 50 % of the total current delivered to each electrode in the pair. Specific ECAP measures were: (1) threshold and slope of the input/output (I/O) functions, (2) amplitude for a masker-probe interval of 1500 ?sec (measure of refractory recovery), and (3) the relative location of spread-of-excitation (SOE) functions among virtual channels and adjacent physical electrodes. Measures for virtual channels were compared with those for the flanking physical electrodes using a multivariate analysis of variance. Results There were no statistically significant differences between physical electrodes and virtual channels for ECAP thresholds, slope of the I/O function, or refractory recovery. On average, SOE functions for the virtual channels were spatially located approximately halfway between SOE functions for the adjacent physical electrodes. Conclusions Results from this study suggest that virtual channels produce neural recruitment patterns with properties similar to those elicited by the adjacent physical electrodes. PMID:21187752

Hughes, Michelle L.; Goulson, Adam M.

2011-01-01

319

Enhancement of auditory-evoked potentials in musicians reflects an influence of expertise but not selective attention.  

PubMed

Instrumental tones and, in some instances, simple sine-wave tones were shown to evoke stronger auditory-evoked responses in musicians compared to nonmusicians. This effect was taken as an example for plasticity in the auditory cortex elicited by training. To date, however, it is unknown whether an enlarged cortical representation for (instrumental) tones or increased neuronal activity provoked by focused attention in musicians accounts for the reported difference. In an attempt to systematically investigate the influence of attention on the processing of simple sine wave and instrumental tones, we compared auditory-evoked potentials recorded from musicians and nonmusicians. During the electroencephalogram recording, the participants were involved in tasks requiring selective attention to specific sound features such as pitch or timbre. Our results demonstrate that the effect of selective attention on the auditory event-related potential (AEP) has a different time course and shows a different topography than the reproduced effect of music expertise at the N1 component or the previously demonstrated effect at the P2 component. N1 peak potentials were unaffected by attention modulation. These results indicate that the effect of music expertise, which was traced by current density mapping to the auditory cortex, is not primarily caused by selective attention, and it supports the view that increased AEPs on tones in musicians reflect an enlarged neuronal representation for specific sound features of these tones. However, independent from the N1-P2 complex, attention evoked an Nd-like negative component in musicians but not in nonmusicians, which suggests that plasticity also affects top-down processes. PMID:18457513

Baumann, Simon; Meyer, Martin; Jäncke, Lutz

2008-12-01

320

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

PubMed

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

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

2014-02-01

321

Neonatal brainstem dysfunction risks infant social engagement  

PubMed Central

The role of the brainstem in mediating social signaling in phylogenetic ancestral organisms has been demonstrated. Evidence for its involvement in social engagement in human infants may deepen the understanding of the evolutionary pathway of humans as social beings. In this longitudinal study, neonatal brainstem functioning was measured by auditory brainstem-evoked responses (ABRs) in 125 healthy neonates born prematurely before 35 weeks’ gestational age. At 4 months, infants were tested in a set of structured vignettes that required varying levels of social engagement and cardiac vagal tone was assessed. Data show that neonates with a disrupted I–V waveform, evident mostly by delayed wave V, exhibit shorter latencies to gaze averts in episodes involving direct face-to-face interactions but engage gaze as controls when interacting with masked agents or with agents whose faces are partly veiled by toys. Analysis of variance of infants’ social engagement with ABR, neonatal risk, maternal stress and cardiac vagal tone showed a main effect for ABR and an ABR by gestational age interaction. The integrity of brainstem transmission of sensory information during the final weeks of gestation may scaffold the development of social disengagement, thereby attesting to the brainstem's preserved evolutionary role in developing humans as social organisms prior to engaging in social encounters. PMID:22146141

Sopher, Koreen; Kurtzman, Lea; Galili, Giora; Feldman, Ruth; Kuint, Jacob

2013-01-01

322

Developmental Plasticity in the Human Auditory Brainstem  

PubMed Central

Development of the human auditory brainstem is thought to be primarily complete by the age of ~2 years, such that subsequent sensory plasticity is confined primarily to the cortex. However, recent findings have revealed experience-dependent developmental plasticity in the mammalian auditory brainstem in an animal model. It is not known whether the human system demonstrates similar changes and whether experience with sounds composed of acoustic elements relevant to speech may alter brainstem response characteristics. We recorded brainstem responses evoked by both click and speech syllables in children between the ages of 3 and 12 years. Here, we report a neural response discrepancy in brainstem encoding of these two sounds, observed in 3- to 4-year-old children but not in school-age children. Whereas all children exhibited identical neural activity to a click, 3- to 4-year-old children displayed delayed and less synchronous onset and sustained neural response activity when elicited by speech compared with 5- to 12-year-olds. These results suggest that the human auditory system exhibits developmental plasticity, in both frequency and time domains, for sounds that are composed of acoustic elements relevant to speech. The findings are interpreted within the contexts of stimulus-related differences and experience-dependent plasticity. PMID:18400899

Johnson, Krista L.; Nicol, Trent; Zecker, Steven G.; Kraus, Nina

2009-01-01

323

Effect of interphase gap and pulse duration on electrically evoked potentials is correlated with auditory nerve survival  

PubMed Central

We investigated the effect of pulse duration (PD) and interphase-gap (IPG) on the electrically-evoked auditory brain stem response (EABR) and viiith nerve compound action potential (ECAP) of deafened guinea pigs in order to test the hypothesis that the extent of change in these neural responses is affected by the histological status of the auditory nerve. Fifteen guinea pigs were deafened by co-administration of kanamycin and furosemide. Animals were acutely implanted with an 8-band electrode array at 1, 4 or 12 weeks following deafening. EABR and ECAP input/output functions were recorded in response to charge balanced biphasic current pulses. We determined the change in current required to equalize; (i) the EABR amplitude when the duration of the current pulse was doubled (104 to 208 ?s/phase); and (ii) the EABR and ECAP amplitudes when the IPG was increased from 8 ?s to 58 ?s using a 104 ?s/phase current pulse. Following the completion of each experiment the cochleae were examined quantitatively for spiral ganglion neuron survival. As expected, the current level required to evoke an EABR with equal amplitude was lower when the animal was stimulated with current pulses of 208 compared with 104 ?s/phase. Moreover, the current level required to evoke EABR/ECAPs with equal amplitude was lower when current pulses had an IPG of 58 versus 8 ?s. Importantly, there was a reduction in the magnitude of this effect with greater neural loss; the reduced efficacy of changing both PD and IPG on these electrically-evoked potentials was statistically correlated with neural survival. These results may provide a tool for investigating the contribution of auditory nerve survival to clinical performance among cochlear implant subjects. PMID:16644157

Prado-Guitierrez, Pavel; Fewster, Leonie M.; Heasman, John M.; McKay, Colette M.; Shepherd, Robert K.

2007-01-01

324

Effect of interphase gap and pulse duration on electrically evoked potentials is correlated with auditory nerve survival.  

PubMed

We investigated the effect of pulse duration (PD) and interphase-gap (IPG) on the electrically-evoked auditory brain stem response (EABR) and viiith nerve compound action potential (ECAP) of deafened guinea pigs in order to test the hypothesis that the extent of change in these neural responses is affected by the histological status of the auditory nerve. Fifteen guinea pigs were deafened by co-administration of kanamycin and furosemide. Animals were acutely implanted with an 8-band electrode array at 1, 4 or 12 weeks following deafening. EABR and ECAP input/output functions were recorded in response to charge balanced biphasic current pulses. We determined the change in current required to equalize; (i) the EABR amplitude when the duration of the current pulse was doubled (104-208 micros/phase); and (ii) the EABR and ECAP amplitudes when the IPG was increased from 8 to 58 micros using a 104 micros/phase current pulse. Following the completion of each experiment the cochleae were examined quantitatively for spiral ganglion neuron survival. As expected, the current level required to evoke an EABR with equal amplitude was lower when the animal was stimulated with current pulses of 208 compared with 104 micros/phase. Moreover, the current level required to evoke EABR/ECAPs with equal amplitude was lower when current pulses had an IPG of 58 versus 8 micros. Importantly, there was a reduction in the magnitude of this effect with greater neural loss; the reduced efficacy of changing both PD and IPG on these electrically-evoked potentials was statistically correlated with neural survival. These results may provide a tool for investigating the contribution of auditory nerve survival to clinical performance among cochlear implant subjects. PMID:16644157

Prado-Guitierrez, Pavel; Fewster, Leonie M; Heasman, John M; McKay, Colette M; Shepherd, Robert K

2006-05-01

325

Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.

Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Itoh, Yuji; Iramina, Keiji

2014-05-01

326

Pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) in the early stages of Alzheimer's disease.  

PubMed

Alzheimer's disease (AD) is one of the most common causes of dementia in the world. Patients with AD frequently complain of vision disturbances that do not manifest as changes in routine ophthalmological examination findings. The main causes of these disturbances are neuropathological changes in the visual cortex, although abnormalities in the retina and optic nerve cannot be excluded. Pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) tests are commonly used in ophthalmology to estimate bioelectrical function of the retina and optic nerve. The aim of this study was to determine whether retinal and optic nerve function, measured by PERG and PVEP tests, is changed in individuals in the early stages of AD with normal routine ophthalmological examination results. Standard PERG and PVEP tests were performed in 30 eyes of 30 patients with the early stages of AD. The results were compared to 30 eyes of 30 normal healthy controls. PERG and PVEP tests were recorded in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. Additionally, neural conduction was measured using retinocortical time (RCT)--the difference between P100-wave latency in PVEP and P50-wave implicit time in PERG. In PERG test, PVEP test, and RCT, statistically significant changes were detected. In PERG examination, increased implicit time of P50-wave (P < 0.03) and amplitudes reductions in P50- and N95-waves (P < 0.0001) were observed. In PVEP examination, increased latency of P100-wave (P < 0.0001) was found. A significant increase in RCT (P < 0.0001) was observed. The most prevalent features were amplitude reduction in N95-wave and increased latency of P100-wave which were seen in 56.7% (17/30) of the AD eyes. In patients with the early stages of AD and normal routine ophthalmological examination results, dysfunction of the retinal ganglion cells as well as of the optic nerve is present, as detected by PERG and PVEP tests. These dysfunctions, at least partially, explain the cause of visual disturbances observed in patients with the early stages of AD. PMID:20549299

Krasodomska, Kamila; Lubi?ski, Wojciech; Potemkowski, Andrzej; Honczarenko, Krystyna

2010-10-01

327

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

PubMed

Visual evoked response testing has been one of the most exciting clinical tools to be developed from neurophysiologic research in recent years and has provided us with an objective method of identifying abnormalities of the afferent visual pathways. Investigation were carried out to see whether the head circumference influence the pattern reversal visual evoked potential (PRVEP) parameters. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings in 400 eyes of 200 normal subjects. Two hundred fourty eight eyes were males and 152 eyes were from 76 female subjects recruited from the Central Indian population in the age range of 40-79 years. Visual evoked potential (VEP) recordings were performed in accordance to the standardized methodology of International Federation of Clinical Neurophysiology (IFCN) Committee Recommendations and International Society for Clinical Electrophysiology of Vision (ISCEV) Guidelines and montages were kept as per 10-20 International System of EEG Electrode placements. The stimulus configuration in this study consisted of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on a VEP Monitor by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). VEP latencies, duration and amplitude were measured in all subjects and the data were analyzed. The correlation of all the electrophysiological parameters with head circumference was evaluated by Pearson's correlation co-efficient (r) and its statistical significance was evaluated. The prediction equations for all the VEP parameters with respect to head circumference were derived. We found a positive correlation of P 100 latency and N 155 latency with mean head circumference, while a highly significant negative correlation were noted of P 100 amplitude with head circumference. N 70 latency was significantly correlated with head circumference. P 100 duration showed in negative correlation with head circumference. These findings suggest that VEP latencies, duration and amplitude are influenced by the head circumference of the individual in a sample of healthy subjects and head circumference can be a useful predictor of VEP peak latencies, amplitude and duration. PMID:23671950

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

2012-06-01

328

Cortical and brainstem plasticity in Tourette syndrome and obsessive-compulsive disorder.  

PubMed

Gilles de la Tourette syndrome is characterized by motor/vocal tics commonly associated with psychiatric disorders, including obsessive-compulsive disorder. We investigated primary motor cortex and brainstem plasticity in Tourette patients, exposed and unexposed to chronic drug treatment, with and without psychiatric disturbances. We also investigated primary motor cortex and brainstem plasticity in obsessive-compulsive disorder. We studied 20 Tourette patients with and without psychiatric disturbances, 15 with obsessive-compulsive disorder, and 20 healthy subjects. All groups included drug-naďve patients. We conditioned the left primary motor cortex with intermittent/continuous theta-burst stimulation and recorded motor evoked potentials. We conditioned the supraorbital nerve with facilitatory/inhibitory high-frequency stimulation and recorded the blink reflex late response area. In healthy subjects, intermittent theta-burst increased and continuous theta-burst stimulation decreased motor evoked potentials. Differently, intermittent theta-burst failed to increase and continuous theta-burst stimulation failed to decrease motor evoked potentials in Tourette patients, with and without psychiatric disturbances. In obsessive-compulsive disorder, intermittent/continuous theta-burst stimulation elicited normal responses. In healthy subjects and in subjects with obsessive-compulsive disorder, the blink reflex late response area increased after facilitatory high-frequency and decreased after inhibitory high-frequency stimulation. Conversely, in Tourette patients, with and without psychiatric disturbances, facilitatory/inhibitory high-frequency stimulation left the blink reflex late response area unchanged. Theta-burst and high-frequency stimulation elicited similar responses in drug-naďve and chronically treated patients. Tourette patients have reduced plasticity regardless of psychiatric disturbances. These findings suggest that abnormal plasticity contributes to the pathophysiology of Gilles de la Tourette syndrome. However, obsessive-compulsive disorder patients have normal cortical and brainstem plasticity. © 2014 International Parkinson and Movement Disorder Society. PMID:24996148

Suppa, Antonio; Marsili, Luca; Di Stasio, Flavio; Berardelli, Isabella; Roselli, Valentina; Pasquini, Massimo; Cardona, Francesco; Berardelli, Alfredo

2014-10-01

329

Visual acuity of the midland banded water snake estimated from evoked telencephalic potentials  

Microsoft Academic Search

The visual acuity of seven midland banded water snakes was measured by recording evoked responses from telencephalon to temporally\\u000a modulated square wave grating patterns. Using conventional electrophysiological techniques and signal averaging, high contrast\\u000a square wave gratings of different spatial frequencies were presented. Acuity was estimated by extrapolating relative response\\u000a amplitude\\/log10 spatial frequency functions which yielded an average acuity of 4.25 cycles\\/degree.

Robert A. Baker; Timothy J. Gawne; Michael S. Loop; Sheena Pullman

2007-01-01

330

Towards an Optimization of Stimulus Parameters for Brain-Computer Interfaces Based on Steady State Visual Evoked Potentials  

PubMed Central

Efforts to construct an effective brain-computer interface (BCI) system based on Steady State Visual Evoked Potentials (SSVEP) commonly focus on sophisticated mathematical methods for data analysis. The role of different stimulus features in evoking strong SSVEP is less often considered and the knowledge on the optimal stimulus properties is still fragmentary. The goal of this study was to provide insight into the influence of stimulus characteristics on the magnitude of SSVEP response. Five stimuli parameters were tested: size, distance, colour, shape, and presence of a fixation point in the middle of each flickering field. The stimuli were presented on four squares on LCD screen, with each square highlighted by LEDs flickering with different frequencies. Brighter colours and larger dimensions of flickering fields resulted in a significantly stronger SSVEP response. The distance between stimulation fields and the presence or absence of the fixation point had no significant effect on the response. Contrary to a popular belief, these results suggest that absence of the fixation point does not reduce the magnitude of SSVEP response. However, some parameters of the stimuli such as colour and the size of the flickering field play an important role in evoking SSVEP response, which indicates that stimuli rendering is an important factor in building effective SSVEP based BCI systems. PMID:25398134

Radzikowska, Zofia; Milanowski, Piotr; Ku?, Rafa?; Suffczy?ski, Piotr; Michalska, Magdalena; ?ab?cki, Maciej; Zwoli?ski, Piotr; Durka, Piotr

2014-01-01

331

Determining electrically evoked compound action potential thresholds: A comparison of computer versus human analysis methods  

PubMed Central

Objectives Current cochlear implants (CIs) have telemetry capabilities for measuring the electrically evoked compound action potential (ECAP). Neural Response Telemetry (NRT™; Cochlear) and Neural Response Imaging (NRI; Advanced Bionics [AB]) can measure ECAP responses across a range of stimulus levels to obtain an amplitude growth function. Software-specific algorithms automatically mark the leading negative peak, N1, and the following positive peak/plateau, P2, and apply linear regression to estimate ECAP threshold. Alternatively, clinicians may apply expert judgments to modify the peak markers placed by the software algorithms, and/or use visual detection to identify the lowest level yielding a measurable ECAP response. The goals of this study were to: (1) assess the variability between human and computer decisions for (a) marking N1 and P2, and (b) determination of linear regression threshold (LRT) and visual detection threshold (VDT); and (2) compare LRT and VDT methods within and across human and computer decision methods. Design ECAP amplitude growth functions were measured for three electrodes in each of 20 ears (10 Cochlear Nucleus® 24RE/CI512, and 10 AB CII/90K). LRT, defined as the current level yielding an ECAP with zero amplitude, was calculated for both computer- (C-LRT) and human-picked peaks (H-LRT). VDT, defined as the lowest level resulting in a measurable ECAP response, was also calculated for both computer- (C-VDT) and human-picked peaks (H-VDT). Because NRI assigns peak markers to all waveforms but does not include waveforms with amplitudes less than 20 ?V in its regression calculation, C-VDT for AB subjects was defined as the lowest current level yielding an amplitude ?20 ?V. Results Overall, there were significant correlations between human and computer decisions for peak-marker placement, LRT, and VDT for both manufacturers (r = 0.78 to 1.00, p < 0.001). For Cochlear devices, LRT and VDT correlated equally well for both computer- and human-picked peaks (r = 0.98 to 0.99, p < 0.001), which likely reflects the well-defined NRT algorithm and the lower noise floor in the 24RE and CI512 devices. For AB devices, correlations between LRT and VDT for both peak-picker methods were weaker than for Cochlear devices (r = 0.69 to 0.85, p < 0.001), which likely reflect the higher noise floor of the system. Disagreement between computer and human decisions regarding the presence of an ECAP response occurred for 5.0 % of traces for Cochlear devices and 2.1 % of traces for AB devices. Conclusions Results indicate that human and computer peak-picking methods can be used with similar accuracy for both Cochlear and AB devices. Either C-VDT or C-LRT can be used with equal confidence for Cochlear 24RE and CI512 recipients because both methods are strongly correlated with human decisions. However for AB devices, greater variability exists between different threshold determination methods. This finding should be considered in the context of using ECAP measures to assist with programming CIs. PMID:22885406

Glassman, E. Katelyn; Hughes, Michelle L.

2012-01-01

332

Block-Dependent Sedation during Epidural Anaesthesia is Associated with Delayed Brainstem Conduction  

PubMed Central

Neuraxial anaesthesia produces a sedative and anesthetic-sparing effect. Recent evidence suggests that spinal cord anaesthesia modifies reticulo-thalamo-cortical arousal by decreasing afferent sensory transmission. We hypothesized that epidural anaesthesia produces sensory deafferentation-dependent sedation that is associated with impairment of brainstem transmission. We used brainstem auditory evoked potentials (BAEP) to evaluate reticular function in 11 volunteers. Epidural anaesthesia was induced with 2% 2-chloroprocaine. Hemodynamic and respiratory responses, sensory block level, sedation depth and BAEP were assessed throughout induction and resolution of epidural anaesthesia. Sedation was evaluated using verbal rating score (VRS), observer's assessment alertness/sedation (OAA/S) score, and bispectral index (BIS). Prediction probability (PK) was used to associate sensory block with sedation, as well as BIS with other sedation measures. Spearman rank order correlation was used to associate block level and sedation with the absolute and interpeak BAEP latencies. Sensory block level significantly predicted VRS (PK = 0.747), OAA/S score (PK = 0.748) and BIS. Bispectral index predicted VRS and OAA/S score (PK = 0.728). The latency of wave III of BAEP significantly correlated with sedation level (rho = 0.335, P < 0.01) and sensory block (rho = 0.394, P < 0.01). The other BAEP parameters did not change during epidural anaesthesia. Hemodynamic and respiratory responses remained stable throughout the study. Sedation during epidural anaesthesia depends on sensory block level and is associated with detectable block-dependent alterations in the brainstem auditory evoked responses. Sensory deafferentation may reduce CNS alertness through mechanisms related to brainstem neural activity. PMID:15220178

Wadhwa, Anupama; Shah, Yunus M.; Lin, Chum-Ming; Haugh, Gilbert S.; Sessler, Daniel I.

2005-01-01

333

RADIATION ASSOCIATED BRAINSTEM INJURY  

PubMed Central

Publications relating brainstem radiation toxicity to quantitative dose and dose–volume measures derived from three-dimensional treatment planning were reviewed. Despite the clinical importance of brainstem toxicity, most studies reporting brainstem effects after irradiation have fewer than 100 patients. There is limited evidence relating toxicity to small volumes receiving doses above 60–64 Gy using conventional fractionation and no definitive criteria regarding more subtle dose–volume effects or effects after hypofractionated treatment. On the basis of the available data, the entire brainstem may be treated to 54 Gy using conventional fractionation using photons with limited risk of severe or permanent neurological effects. Smaller volumes of the brainstem (1–10 mL) may be irradiated to maximum doses of 59 Gy for dose fractions ?2 Gy; however, the risk appears to increase markedly at doses >64 Gy. PMID:20171516

Mayo, Charles; Yorke, Ellen; Merchant, Thomas E.

2010-01-01

334

Clinical characteristics associated with different strengths of loudness dependence of auditory evoked potentials (LDAEP) in major depressive disorder.  

PubMed

Loudness dependence of auditory evoked potentials (LDAEP), also called as intensity dependence of auditory evoked potentials (IDAP), has been proposed as a potential marker for central serotonergic tone and has been noticed for its possible clinical implications in depression. However, its distributions in major depressive disorder (MDD) and factors affecting it are largely unknown. In this study, we examined its distribution and relationships with various demographic and clinical variables in MDD patients. In 143 MDD patients, the LDAEP was measured using five intensities of auditory stimulus. The influences of ten independent variables (age, gender, education years, marital status, psychiatric family history, age of onset, suicide attempt history, depression severity, later augmentation of mood stabilizer, and smoking status) on the LDAEP strength were examined using univariate analyses and data mining method. The mean (±S.D.) LDAEP was 0.90 (±0.73)?V/10dB (-0.78-3.83?V/10dB). Female gender, smoking, and being married were consistently associated with a weaker LDAEP. In the pathway model, sequential combination of being male, living alone, and older age predicted the strongest LDAEP, whereas female gender, older age, and smoking predicted the weakest LDAEP. These variables need to be considered when interpreting the LDAEP. PMID:23021319

Min, Jung-Ah; Lee, Seung-Hwan; Lee, Seung-Yup; Chae, Jeong-Ho; Lee, Chang-Uk; Park, Young-Min; Bae, Sung-Man

2012-12-30

335

[Auditory brain stem evoked potentials in the evaluation of chronic fatigue syndrome].  

PubMed

The Chronic Fatigue Syndrome (CFS) was formally defined to describe disabling fatigue of multifactorial ethology with depression and immunologic dysfunctions linked to some currently recognized infectious agents. In most cases neurophysiological tests reveal abnormalities. In this paper the Authors use low (11 pps) and high (51-71 pps) frequency ABR to evaluate the electrophysiological function of auditory brainstem responses. Eighteen patients with suspected CFS, between the ages of 17 and 63, were examined. Eleven subjects had clinically diagnosed "true" CFS (CDC criteria modified by Fukuda). The 11 pps frequency test did not reveal a high number of abnormalities in the patients in question. However, the high frequency stimulation test (with 51 and 71 pps) which was statistically significant (P = 0.009) revealed numerous aberrations in 7 patients; absence of the first wave in 1 case, in 5 numerous wave gap delays and in 1 patient absence of the first wave and numerous wave gap delays. The high frequency test did not show many abnormalities for the 4 remaining patients. For the 7 "non CFS" subjects, the clinical-audiological comparison showed no statistical significance (P = 0.920). The Authors hypothesize that the absence of the first wave in the CFS Subject may well indicate a cyto-neural junction disease in the organ of Corti. The combined analysis of clinical and audiological data showed that the described tests are more reliable when employed in dealing with patients with clinically assessed "true" CFS. PMID:8711992

Bianchedi, M; Croce, A; Moretti, A; Neri, G; Barberio, A; Iezzi, A; Pizzigallo, E

1995-12-01

336

Auditory brainstem responses in children with Cornelia de Lange syndrome  

Microsoft Academic Search

Auditory brainstem evoked responses (ABRs) were recorded in 10 Japanese infants and children with Cornelia de Lange syndrome to determine the level of the lesion causing their poor response to sound. Behavioral audiometry showed severe threshold elevation compared to an age-matched control group. ABR thresholds, peak latencies of wave I and IV and the peak interval latency of waves I–V

Kimitaka Kaga; Fumi Tamai; Eiji Kitazumi; Kazuo Kodama

1995-01-01

337

The need to add motor evoked potential monitoring to somatosensory and electromyographic monitoring in cervical spine surgery  

PubMed Central

Intraoperative neural monitoring (IONM), utilizing somatosensory evoked potentials (SEP) and electromyography (EMG), was introduced to cervical spine surgery in the late 1980's. However, as SEP only provided physiological data regarding the posterior cord, new motor deficits were observed utilizing SEP alone. This prompted the development of motor evoked potential monitoring (MEP) which facilitated real-time assessment of the anterior/anterolateral spinal cord. Although all three modalities, SEP, EMG, and MEP, are routinely available for IONM of cervical spine procedures, MEP are not yet routinely employed. The purpose of this review is to emphasize that MEP should now routinely accompany SEP and EMG when performing IONM of cervical spine surgery. Interestingly, one of the most common reasons for malpractice suits involving the cervical spine, is quadriparesis/quadriplegia following a single level anterior cervical diskectomy and fusion (ACDF). Previously, typical allegations in these suits included; negligent surgery, lack of informed consent, failure to diagnose/treat, and failure to brace. Added to this list, perhaps, as the 5th most reason for a suit will be failure to monitor with MEP. This review documents the value of MEP monitoring in addition to SEP and EMG monitoring in cervical spine surgery. The addition of MEP0 should minimize major motor injuries, and more accurately and reliably detect impending anterior cord deterioration that may be missed with SEP monitoring alone. PMID:24340237

Epstein, Nancy E.

2013-01-01

338

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

PubMed Central

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

2013-01-01

339

The origin, and application of somatosensory evoked potentials as a neurophysiological technique to investigate neuroplasticity  

PubMed Central

Somatosensory evoked potentionals (SEPs) can be used to elucidate differences in cortical activity associated with a spinal manipulation (SM) intervention. The purpose of this narrative review is to overview the origin and application of SEPs, a neurophysiological technique to investigate neuroplasticity. Summaries of: 1) parameters for SEP generation and waveform recording; 2) SEP peak nomenclature, interpretation and generators; 3) peaks pertaining to tactile information processing (relevant to both chiropractic and other manual therapies); 4) utilization and application of SEPs; 5) SEPs concurrent with an experimental task and at baseline/control/pretest; 6) SEPs pain studies; and 7) SEPs design (pre/post) and neural reorganization/neuroplasticity; and 8) SEPs and future chiropractic research are all reviewed. Understanding what SEPs are, and their application allows chiropractors, educators, and other manual therapists interested in SM to understand the context, and importance of research findings from SM studies that involve SEPs. PMID:24932021

Passmore, Steven R.; Murphy, Bernadette; Lee, Timothy D.

2014-01-01

340

Action Potential-Evoked Calcium Release Is Impaired in Single Skeletal Muscle Fibers from Heart Failure Patients  

PubMed Central

Background Exercise intolerance in chronic heart failure (HF) has been attributed to abnormalities of the skeletal muscles. Muscle function depends on intact excitation-contraction coupling (ECC), but ECC studies in HF models have been inconclusive, due to deficiencies in the animal models and tools used to measure calcium (Ca2+) release, mandating investigations in skeletal muscle from HF patients. The purpose of this study was to test the hypothesis that Ca2+ release is significantly impaired in the skeletal muscle of HF patients in whom exercise capacity is severely diminished compared to age-matched healthy volunteers. Methods and Findings Using state-of-the-art electrophysiological and optical techniques in single muscle fibers from biopsies of the locomotive vastus lateralis muscle, we measured the action potential (AP)-evoked Ca2+ release in 4 HF patients and 4 age-matched healthy controls. The mean peak Ca2+ release flux in fibers obtained from HF patients (10±1.2 µM/ms) was markedly (2.6-fold) and significantly (p<0.05) smaller than in fibers from healthy volunteers (28±3.3 µM/ms). This impairment in AP-evoked Ca2+ release was ubiquitous and was not explained by differences in the excitability mechanisms since single APs were indistinguishable between HF patients and healthy volunteers. Conclusions These findings prove the feasibility of performing electrophysiological experiments in single fibers from human skeletal muscle, and offer a new approach for investigations of myopathies due to HF and other diseases. Importantly, we have demonstrated that one step in the ECC process, AP-evoked Ca2+ release, is impaired in single muscle fibers in HF patients. PMID:25310188

DiFranco, Marino; Quinonez, Marbella; Shieh, Perry; Fonarow, Gregg C.; Cruz, Daniel; Deng, Mario C.; Vergara, Julio L.; Middlekauff, Holly R.

2014-01-01

341

Deep brain stimulation of the ventral hippocampus restores deficits in processing of auditory evoked potentials in a rodent developmental disruption model of schizophrenia  

PubMed Central

Existing antipsychotic drugs are most effective at treating the positive symptoms of schizophrenia, but their relative efficacy is low and they are associated with considerable side effects. In this study deep brain stimulation of the ventral hippocampus was performed in a rodent model of schizophrenia (MAM-E17) in an attempt to alleviate one set of neurophysiological alterations observed in this disorder. Bipolar stimulating electrodes were fabricated and implanted, bilaterally, into the ventral hippocampus of rats. High frequency stimulation was delivered bilaterally via a custom-made stimulation device and both spectral analysis (power and coherence) of resting state local field potentials and amplitude of auditory evoked potential components during a standard inhibitory gating paradigm were examined. MAM rats exhibited alterations in specific components of the auditory evoked potential in the infralimbic cortex, the core of the nucleus accumbens, mediodorsal thalamic nucleus, and ventral hippocampus in the left hemisphere only. DBS was effective in reversing these evoked deficits in the infralimbic cortex and the mediodorsal thalamic nucleus of MAM-treated rats to levels similar to those observed in control animals. In contrast stimulation did not alter evoked potentials in control rats. No deficits or stimulation-induced alterations were observed in the prelimbic and orbitofrontal cortices, the shell of the nucleus accumbens or ventral tegmental area. These data indicate a normalization of deficits in generating auditory evoked potentials induced by a developmental disruption by acute high frequency, electrical stimulation of the ventral hippocampus. PMID:23269227

Ewing, Samuel G.; Grace, Anthony A.

2012-01-01

342

Cortical representation of the vestibular system as evidenced by brain electrical activity mapping of vestibular late evoked potentials.  

PubMed

We examined the space and temporal distributions of the rotatory evoked brain electrical activity patterns (brain electrical activity mapping of vestibular evoked potentials [VestEP]) in humans. We performed a longitudinal scalp line analysis, transversal line analysis, and clockwise/counterclockwise rotation analysis of the VestEP principal components in 75 healthy persons aged 22 to 30 years (mean: 25.8). We found that the shortest VestEP latencies and the highest amplitudes were registered in a relatively distinct cortical area that is covered by the transversal electrode line T3-C3-Cz-C4-T4, in accordance with the 10/20 international electrode scheme. This area corresponds to the posterior part of the frontal lobe (Brodmann's area 4, the primary motor field of the isocortex) and the anterior parts of the cerebral parietal lobe (the gyrus postcentralis, which corresponds to the primary somatosensory fields, Brodmann's areas 1, 2, and 3). In this article, we discuss a method of investigation that exhibits the VestEPs, and we review one normal case and three typical cases of pathologic VestEPs. PMID:11338651

Schneider, D; Schneider, L; Claussen, C F; Kolchev, C

2001-04-01

343

Brainstem neurons survive the identical ischemic stress that kills higher neurons: insight to the persistent vegetative state.  

PubMed

Global ischemia caused by heart attack, pulmonary failure, near-drowning or traumatic brain injury often damages the higher brain but not the brainstem, leading to a 'persistent vegetative state' where the patient is awake but not aware. Approximately 30,000 U.S. patients are held captive in this condition but not a single research study has addressed how the lower brain is preferentially protected in these people. In the higher brain, ischemia elicits a profound anoxic depolarization (AD) causing neuronal dysfunction and vasoconstriction within minutes. Might brainstem nuclei generate less damaging AD and so be more resilient? Here we compared resistance to acute injury induced from simulated ischemia by 'higher' hippocampal and striatal neurons versus brainstem neurons in live slices from rat and mouse. Light transmittance (LT) imaging in response to 10 minutes of oxygen/glucose deprivation (OGD) revealed immediate and acutely damaging AD propagating through gray matter of neocortex, hippocampus, striatum, thalamus and cerebellar cortex. In adjacent brainstem nuclei, OGD-evoked AD caused little tissue injury. Whole-cell patch recordings from hippocampal and striatal neurons under OGD revealed sudden membrane potential loss that did not recover. In contrast brainstem neurons from locus ceruleus and mesencephalic nucleus as well as from sensory and motor nuclei only slowly depolarized and then repolarized post-OGD. Two-photon microscopy confirmed non-recoverable swelling and dendritic beading of hippocampal neurons during OGD, while mesencephalic neurons in midbrain appeared uninjured. All of the above responses were mimicked by bath exposure to 100 µM ouabain which inhibits the Na+/K+ pump or to 1-10 nM palytoxin which converts the pump into an open cationic channel. Therefore during ischemia the Na+/K+ pump of higher neurons fails quickly and extensively compared to naturally resilient hypothalamic and brainstem neurons. The selective survival of lower brain regions that maintain vital functions will support the persistent vegetative state. PMID:24802253

Brisson, C Devin; Hsieh, Yi-Ting; Kim, Danielle; Jin, Albert Y; Andrew, R David

2014-01-01

344

In-air evoked potential audiometry of grey seals (Halichoerus grypus) from the North and Baltic Seas.  

PubMed

In-air anthropogenic sound has the potential to affect grey seal (Halichoerus grypus) behaviour and interfere with acoustic communication. In this study, a new method was used to deliver acoustic signals to grey seals as part of an in-air hearing assessment. Using in-ear headphones with adapted ear inserts allowed for the measurement of auditory brainstem responses (ABR) on sedated grey seals exposed to 5-cycle (2-1-2) tone pips. Thresholds were measured at 10 frequencies between 1-20 kHz. Measurements were made using subcutaneous electrodes on wild seals from the Baltic and North Seas. Thresholds were determined by both visual and statistical approaches (single point F-test) and good agreement was obtained between the results using both methods. The mean auditory thresholds were ?40 dB re 20 µPa peak equivalent sound pressure level (peSPL) between 4-20 kHz and showed similar patterns to in-air behavioural hearing tests of other phocid seals between 3 and 20 kHz. Below 3 kHz, a steep reduction in hearing sensitivity was observed, which differed from the rate of decline in sensitivity obtained in behavioural studies on other phocids. Differences in the rate of decline may reflect influence of the ear inserts on the ability to reliably transmit lower frequencies or interference from the structure of the distal end of the ear canal. PMID:24632891

Ruser, Andreas; Dähne, Michael; Sundermeyer, Janne; Lucke, Klaus; Houser, Dorian S; Finneran, James J; Driver, Jörg; Pawliczka, Iwona; Rosenberger, Tanja; Siebert, Ursula

2014-01-01

345

In-Air Evoked Potential Audiometry of Grey Seals (Halichoerus grypus) from the North and Baltic Seas  

PubMed Central

In-air anthropogenic sound has the potential to affect grey seal (Halichoerus grypus) behaviour and interfere with acoustic communication. In this study, a new method was used to deliver acoustic signals to grey seals as part of an in-air hearing assessment. Using in-ear headphones with adapted ear inserts allowed for the measurement of auditory brainstem responses (ABR) on sedated grey seals exposed to 5-cycle (2-1-2) tone pips. Thresholds were measured at 10 frequencies between 1–20 kHz. Measurements were made using subcutaneous electrodes on wild seals from the Baltic and North Seas. Thresholds were determined by both visual and statistical approaches (single point F-test) and good agreement was obtained between the results using both methods. The mean auditory thresholds were ?40 dB re 20 µPa peak equivalent sound pressure level (peSPL) between 4–20 kHz and showed similar patterns to in-air behavioural hearing tests of other phocid seals between 3 and 20 kHz. Below 3 kHz, a steep reduction in hearing sensitivity was observed, which differed from the rate of decline in sensitivity obtained in behavioural studies on other phocids. Differences in the rate of decline may reflect influence of the ear inserts on the ability to reliably transmit lower frequencies or interference from the structure of the distal end of the ear canal. PMID:24632891

Ruser, Andreas; Dahne, Michael; Sundermeyer, Janne; Lucke, Klaus; Houser, Dorian S.; Finneran, James J.; Driver, Jorg; Pawliczka, Iwona; Rosenberger, Tanja; Siebert, Ursula

2014-01-01

346

Early and late activity in somatosensory cortex reflects changes in bodily self-consciousness: an evoked potential study.  

PubMed

How can we investigate the brain mechanisms underlying self-consciousness? Recent behavioural studies on multisensory bodily perception have shown that multisensory conflicts can alter bodily self-consciousness such as in the "full body illusion" (FBI) in which changes in self-identification with a virtual body and tactile perception are induced. Here we investigated whether experimental changes in self-identification during the FBI are accompanied by activity changes in somatosensory cortex by recording somatosensory-evoked potentials (SEPs). To modulate self-identification, participants were filmed by a video camera from behind while their backs were stroked, either synchronously (illusion condition) or asynchronously (control condition) with respect to the stroking seen on their virtual body. Tibial nerve SEPs were recorded during the FBI and analysed using evoked potential (EP) mapping. Tactile mislocalisation was measured using the crossmodal congruency task. SEP mapping revealed five sequential periods of brain activation during the FBI, of which two differed between the illusion condition and the control condition. Activation at 30-50 ms (corresponding to the P40 component) in primary somatosensory cortex was stronger in the illusion condition. A later activation at ?110-200 ms, likely originating in higher-tier somatosensory regions in parietal cortex, was stronger and lasted longer in the control condition. These data show that changes in bodily self-consciousness modulate activity in primary and higher-tier somatosensory cortex at two distinct processing steps. We argue that early modulations of primary somatosensory cortex may be a consequence of (1) multisensory integration of synchronous vs. asynchronous visuo-tactile stimuli and/or (2) differences in spatial attention (to near or far space) between the conditions. The later activation in higher-tier parietal cortex (and potentially other regions in temporo-parietal and frontal cortex) likely reflects the detection of visuo-tactile conflicts in the asynchronous condition. PMID:22546336

Aspell, J E; Palluel, E; Blanke, O

2012-08-01

347

Innovative neurophysiological methods in itch research: long-latency evoked potentials after electrical and thermal stimulation in patients with atopic dermatitis.  

PubMed

The aim of this study was to examine the findings of innovative neurophysiological methods of itch research. Short-latency and pain-related somatosensory-evoked potentials after electrical stimulation, as well as long-latency evoked potentials after thermal stimulation were studied in 38 patients with atopic dermatitis (AD) and 26 healthy volunteers. Quantitative Sensory Testing of thermal perception was performed in 22 patients with AD from the main AD group and in 15 healthy volunteers. Brain hyperactivity to electrical stimuli, delayed thermal-evoked potentials and elevated thermal thresholds were revealed in patients with AD compared with healthy controls. The data indicate small nerve fibre dysfunction in patients with AD, which may contribute to the pathogenesis of AD and chronic itch. The study demonstrates objective approaches to assess the function of small nerve fibres in patients with chronic itch. PMID:21710104

Yudina, Marina M; Toropina, Galina G; Lvov, Andrey; Gieler, Uwe

2011-10-01

348

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

PubMed

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

Shkol'nik, V M; Pogorelov, A V

1998-05-01

349

Motor-Evoked Potential Confirmation of Functional Improvement by Transplanted Bone Marrow Mesenchymal Stem Cell in the Ischemic Rat Brain  

PubMed Central

This study investigated the effect of bone marrow mesenchymal stem cells (BMSCs) on the motor pathway in the transient ischemic rat brain that were transplanted through the carotid artery, measuring motor-evoked potential (MEP) in the four limbs muscle and the atlantooccipital membrane, which was elicited after monopolar and bipolar transcortical stimulation. After monopolar stimulation, the latency of MEP was significantly prolonged, and the amplitude was less reduced in the BMSC group in comparison with the control group (P < .05). MEPs induced by bipolar stimulation in the left forelimb could be measured in 40% of the BMSC group and the I wave that was not detected in the control group was also detected in 40% of the BMSC group. Our preliminary results imply that BMSCs transplanted to the ischemic rat brain mediate effects on the functional recovery of the cerebral motor cortex and the motor pathway. PMID:21772790

Jang, Dong-Kyu; Park, Sang-In; Han, Young-Min; Jang, Kyung-Sool; Park, Moon-Seo; Chung, Young-An; Kim, Min-Wook; Maeng, Lee-So; Huh, Pil-Woo; Yoo, Do-Sung; Jung, Seong-Whan

2011-01-01

350

INHALATIONAL EXPOSURE TO CARBONYL SULFIDE (COS) PRODUCES BRAIN LESIONS AND ALTERED BRAINSTEM AUDITORY (BAER) AND SOMATOSENSORY (SEP) EVOKED POTENTIALS IN FISHCER 344N RATS.  

EPA Science Inventory

Because of the amount of carbonyl sulfide (COS) emissions and the lack of toxicological data, COS was listed in the Clean Air Act of 1990 as a Hazardous Air Pollutant. In 1999 COS was nominated by the US EPA to the National Toxicology Program for additional toxicological investig...

351

Effects of dimethylarsinic and dimethylarsinous acid on evoked synaptic potentials in hippocampal slices of young and adult rats  

SciTech Connect

In this study, the effects of pentavalent dimethylarsinic acid ((CH{sub 3}){sub 2}AsO(OH); DMA{sup V}) and trivalent dimethylarsinous acid ((CH{sub 3}){sub 2}As(OH); DMA{sup III}) on synaptic transmission generated by the excitatory Schaffer collateral-CA1 synapse were tested in hippocampal slices of young (14-21 day-old) and adult (2-4 month-old) rats. Both compounds were applied in concentrations of 1 to 100 {mu}mol/l. DMA{sup V} had no effect on the amplitudes of evoked fEPSPs or the induction of LTP recorded from the CA1 dendritic region either in adult or in young rats. However, application of DMA{sup III} significantly reduced the amplitudes of evoked fEPSPs in a concentration-dependent manner with a total depression following application of 100 {mu}mol/l DMA{sup III} in adult and 10 {mu}mol/l DMA{sup III} in young rats. Moreover, DMA{sup III} significantly affected the LTP-induction. Application of 10 {mu}mol/l DMA{sup III} resulted in a complete failure of the postsynaptic potentiation of the fEPSP amplitudes in slices taken both from adult and young rats. The depressant effect was not reversible after a 30-min washout of the DMA{sup III}. In slices of young rats, the depressant effects of DMA{sup III} were more pronounced than in those taken from adult ones. Compared to the (absent) effect of DMA{sup V} on synaptic transmission, the trivalent compound possesses a considerably higher neurotoxic potential.

Krueger, Katharina [Institut fuer Physiologie I, Universitaetsklinikum Muenster, Robert-Koch-Strasse 27a, D-48149 Muenster (Germany)], E-mail: katharina.krueger@uni-muenster.de; Repges, Hendrik [Institut fuer Physiologie I, Universitaetsklinikum Muenster, Robert-Koch-Strasse 27a, D-48149 Muenster (Germany); Hippler, Joerg; Hartmann, Louise M.; Hirner, Alfred V. [Institut fuer Umweltanalytik, Universitaet Duisburg-Essen, Universitaetsstrasse 3-5, D-45141 Essen (Germany); Straub, Heidrun [Institut fuer Physiologie I, Universitaetsklinikum Muenster, Robert-Koch-Strasse 27a, D-48149 Muenster (Germany); Binding, Norbert [Institut fuer Arbeitsmedizin, Universitaetsklinikum Muenster, Robert-Koch-Strasse 51, D-48149 Muenster (Germany); Musshoff, Ulrich [Institut fuer Physiologie I, Universitaetsklinikum Muenster, Robert-Koch-Strasse 27a, D-48149 Muenster (Germany)

2007-11-15

352

Flash visual evoked potentials in patients with periventricular leucomalacia in children less than 1 year of age  

PubMed Central

Background and Aim: Children with periventricular leucomalacia (PVL) are known to have visual impairment of various forms starting from reduced vision, field defects, congnitive problems, and problems with hand eye coordination. There is very scant data/literature on the visual evoked potentials (VEPs) at an early age in children with PVL. We did a study to evaluate the flash visual evoked potentials (fVEPs) in children with PVL less than 1 year of age. Materials and Methods: A total of nine children diagnosed as having PVL on magnetic resonance imaging were included in the study. The mean age was 9.7± 3.5 months. All children underwent handheld fVEPs under sedation at two different flash frequencies 1.4 and 8 Hz. Results: The mean latency of N1 and P1 on stimulation with 1.4 Hz was 47.9± 15.2 and 77.7± 26.0 ms, respectively. However, on stimulation with 8 Hz the mean latency of N1 and P1 was 189.8± 25.6 and 238.4± 33.6 ms, respectively. The mean amplitude with 1.4 Hz and 8 stimulation frequency was 5.6± 4.5 and 5.59± 3 mV, respectively. Conclusion: We have found for the first time that there is a change in the latency and the delay occurs at 8 Hz frequency but not at 1.4 Hz. We also conclude that amplitudes by fVEPs may be normal even in presence of periventricular changes. The amplitudes of fVEPs are not reliable in children with PVL. PMID:24343595

Jethani, Jitendra; Jethani, Monika

2013-01-01

353

Nucleus accumbens deep brain stimulation produces region-specific alterations in local field potential oscillations and evoked responses in vivo  

PubMed Central

Deep brain stimulation of the nucleus accumbens (NAC) region is an effective therapeutic avenue for several psychiatric disorders that are not responsive to traditional treatment strategies. Nonetheless, the mechanisms by which DBS achieves therapeutic effects remain unclear. We showed previously that high-frequency (HF) NAC DBS suppressed pyramidal cell firing and enhanced slow local field potential (LFP) oscillations in the orbitofrontal cortex (OFC) via antidromic activation of corticostriatal recurrent inhibition. Using simultaneous multisite LFP recordings in urethane-anesthetized rats, we now show that NAC DBS delivered for 90 minutes at high or low frequency (LF) selectively affects spontaneous and evoked LFP oscillatory power and coherence within and between the medial prefrontal cortex (mPFC), lateral OFC, mediodorsal thalamus (MD), and NAC. Compared to LF or sham DBS, HF DBS enhanced spontaneous slow oscillations and potentiated evoked LFP responses only in OFC. HF DBS also produced widespread increases in spontaneous beta and gamma power and enhanced coherent beta activity between MD and all other regions. In contrast, LF DBS elevated theta power in MD and NAC. Analysis of acute NAC-induced oscillations showed that HF DBS increased and LF DBS decreased induced relative gamma coherence compared to sham DBS. These data suggest that HF (therapeutic) and LF (possibly deleterious) NAC DBS produce distinct region-specific and frequency band-specific changes in LFP oscillations. NAC DBS may achieve therapeutic effects by enhancing rhythmicity and synchronous inhibition within and between afferent structures, thereby normalizing function of a neural circuit that shows aberrant activity in obsessive-compulsive disorder and depression. PMID:19386932

Grace, Anthony A.

2009-01-01

354

Pure phase-locking of beta/gamma oscillation contributes to the N30 frontal component of somatosensory evoked potentials  

PubMed Central

Background Evoked potentials have been proposed to result from phase-locking of electroencephalographic (EEG) activities within specific frequency bands. However, the respective contribution of phasic activity and phase resetting of ongoing EEG oscillation remains largely debated. We here applied the EEGlab procedure in order to quantify the contribution of electroencephalographic oscillation in the generation of the frontal N30 component of the somatosensory evoked potentials (SEP) triggered by median nerve electrical stimulation at the wrist. Power spectrum and intertrial coherence analysis were performed on EEG recordings in relation to median nerve stimulation. Results The frontal N30 component was accompanied by a significant phase-locking of beta/gamma oscillation (25–35 Hz) and to a lesser extent of 80 Hz oscillation. After the selection in each subject of the trials for which the power spectrum amplitude remained unchanged, we found pure phase-locking of beta/gamma oscillation (25–35 Hz) peaking about 30 ms after the stimulation. Transition across trials from uniform to normal phase distribution revealed temporal phase reorganization of ongoing 30 Hz EEG oscillations in relation to stimulation. In a proportion of trials, this phase-locking was accompanied by a spectral power increase peaking in the 30 Hz frequency band. This corresponds to the complex situation of 'phase-locking with enhancement' in which the distinction between the contribution of phasic neural event versus EEG phase resetting is hazardous. Conclusion The identification of a pure phase-locking in a large proportion of the SEP trials reinforces the contribution of the oscillatory model for the physiological correlates of the frontal N30. This may imply that ongoing EEG rhythms, such as beta/gamma oscillation, are involved in somatosensory information processing. PMID:17877800

Cheron, Guy; Cebolla, Ana Maria; De Saedeleer, Caty; Bengoetxea, Ana; Leurs, Francoise; Leroy, Axelle; Dan, Bernard

2007-01-01

355

Type-2 diabetes mellitus and auditory brainstem response  

PubMed Central

Objective: Diabetes mellitus (DM) causes pathophysiological changes at multiple organ system. With evoked potential techniques, the brain stem auditory response represents a simple procedure to detect both acoustic nerve and central nervous system pathway damage. The objective was to find the evidence of central neuropathy in diabetes patients by analyzing brainstem audiometry electric response obtained by auditory evoked potentials, quantify the characteristic of auditory brain response in long standing diabetes and to study the utility of auditory evoked potential in detecting the type, site, and nature of lesions. Design: A total of 25 Type-2 DM [13 (52%) males and 12 (48%) females] with duration of diabetes over 5 years and aged over 30 years. The brainstem evoked response audiometry (BERA) was performed by universal smart box manual version 2.0 at 70, 80, and 90 dB. The wave latency pattern and interpeak latencies were estimated. This was compared with 25 healthy controls (17 [68%] males and 8 [32%] females). Result: In Type-2 DM, BERA study revealed that wave-III representing superior olivary complex at 80 dB had wave latency of (3.99 ± 0.24) ms P < 0.001, at 90 dB (3.92 ± 0.28) ms P < 0.001 compared with control. The latency of wave III was delayed by 0.39, 0.42, and 0.42 ms at 70, 80, and 90 dB, respectively. The absolute latency of wave V representing inferior colliculus at 70 dB (6.05 ± 0.27) ms P < 0.001, at 80 dB (5.98 ± 0.27) P < 0.001, and at 90 dB (6.02 ± 0.30) ms P < 0.002 compared with control. The latency of wave-V was delayed by 0.48, 0.47, and 0.50 ms at 70, 80, and 90 dB, respectively. Interlatencies I-III at 70 dB (2.33 ± 0.22) ms P < 0.001, at 80 dB (2.39 ± 0.26) ms P < 0.001, while at 90 dB (2.47 ± 0.25) ms P < 0.001 when compared with control. Interlatencies I-V at 70 dB (4.45 ± 0.29) ms P < 0.001 at 80 dB (4.39 ± 0.34) ms P < 0.001, and at 90 dB (4.57 ± 0.31) ms P < 0.001 compared with control. Out of 25 Type-2 DM, 13 (52%) had diabetic neuropathy, of which 12 (92%) showed abnormal BERA. In nonneuropathic [12 (48%)] only 6 (50%) showed abnormal BERA. Conclusion: Delay in absolute latencies and interpeak latencies by BERA demonstrates defect at level of brainstem and midbrain in long standing Type-2 diabetes subjects, which is more pronounced in those with neuropathy. PMID:24381887

Siddiqi, Sheelu S.; Gupta, Rahul; Aslam, Mohd; Hasan, Syed Abrar; Khan, Shakeel Ahmad

2013-01-01

356

Respiration-modulated membrane potential and chemosensitivity of locus coeruleus neurones in the in vitro brainstem-spinal cord of the neonatal rat.  

PubMed

1. The activity of locus coeruleus (LC) neurones (n = 126) was examined in whole-cell (conventional and amphotericin B-perforated patch) recordings, and the relationship of this activity to the respiratory discharge recorded on the C4 or C5 phrenic nerve roots was determined at different CO2 concentrations (2 and 8 %; bath pH 7. 8 and 7.2) in the in vitro brainstem-spinal cord preparation of the neonatal rat (1-5 days old). 2. In most neurones (n = 105) ongoing activity was modulated at respiratory frequency. Typically, this consisted of a phase of depolarization and increased discharge frequency synchronous with the phrenic burst, followed by a phase of hyperpolarization and inhibition of discharge (n = 94 of 105). The incidence of respiratory modulation decreased from 91 % on P1 to 57 % on P5. 3. Bath application of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 5 microM) or the NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV; 100 microM) abolished both phases of respiratory modulation. The hyperpolarizing phase alone was abolished by the adrenoceptor antagonists idazoxan (5 microM) or phentolamine (0.8 microM). These results indicate that excitatory amino acid pathways are involved in the transmission of both the excitatory and inhibitory components and that the latter involves in addition an alpha2-adrenoceptor-mediated pathway. 4. Increasing the CO2 concentration from 2 to 8 % resulted in a shortening of expiratory duration and weakening or loss of respiratory-phased inhibition; this was accompanied by depolarization, increased discharge frequency and, in those neurones where they were initially present (60 %), an increase in the frequency of subthreshold membrane potential oscillations. The depolarizing response was retained in the presence of tetrodotoxin (TTX, 0.2-1.0 microM). 5. These results indicate that in this neonatal preparation LC neurones form part of the synaptically connected brainstem respiratory network, and that the LC constitutes a site of CO2- or pH-dependent chemoreception. PMID:9806990

Oyamada, Y; Ballantyne, D; Mückenhoff, K; Scheid, P

1998-12-01

357

The Vestibular-Auditory Interaction for Auditory Brainstem Response to Low Frequencies  

PubMed Central

Since saccular projection is sound sensitive, the objective is to investigate the possibility that the saccular projections may contribute to auditory brainstem response to 500?HZ tone burst (ABR500?HZ). During the case-control research, twenty healthy controls compared to forty selected case groups as having chronic and resistant BPPV were evaluated in the audiology department of Hamadan University of Medical Sciences (Hamadan, Iran). Assessment is comprised of audiologic examinations, cervical vestibular evoked myogenic potentials (cVEMPs), and ABR500?HZ. We found that forty affected ears of BPPV patients with decreased vestibular excitability as detected by abnormal cVEMPs had abnormal results in ABR500?HZ, whereas unaffected ears presented normal findings. Multiple comparisons of mean p13, n23 latencies, and peak-to-peak amplitudes between three groups (affected, unaffected, and healthy ears) were significant. In conclusion, the saccular nerves can be projective to auditory bundles and interact with auditory brainstem response to low frequencies. Combine the cVEMPs and ABR500?HZ in battery approach tests of vestibular assessment and produce valuable data for judgment on the site of lesion. Regarding vestibular cooperation for making of wave V, it is reasonable that the term of ABR500?HZ is not adequate and the new term or vestibular-auditory brainstem response to 500?HZ tone burst is more suitable. PMID:25006510

Gohari, Nasrin

2014-01-01

358

Kappa opioid receptor activation potentiates the cocaine-induced increase in evoked dopamine release recorded in vivo in the mouse nucleus accumbens.  

PubMed

Behavioral stressors increase addiction risk in humans and increase the rewarding valence of drugs of abuse including cocaine, nicotine and ethanol in animal models. Prior studies have established that this potentiation of drug reward was mediated by stress-induced release of the endogenous dynorphin opioids and subsequent kappa opioid receptor (KOR) activation. In this study, we used in vivo fast scan cyclic voltammetry to test the hypothesis that KOR activation before cocaine administration might potentiate the evoked release of dopamine from ventral tegmental (VTA) synaptic inputs to the nucleus accumbens (NAc) and thereby increase the rewarding valence of cocaine. The KOR agonist U50488 inhibited dopamine release evoked by either medial forebrain bundle (MFB) or pedunculopontine tegmental nucleus (PPTg) activation of VTA inputs to the shell or core of the mouse NAc. Cocaine administration increased the dopamine response recorded in either the shell or core evoked by either MFB or PPTg stimulation. Administration of U50488 15?min before cocaine blocked the conditioned place preference (CPP) to cocaine, but only significantly reduced the effect of cocaine on the dopamine response evoked by PPTg stimulation to NAc core. In contrast, administration of U50488 60?min before cocaine significantly potentiated cocaine CPP and significantly increased the effects of cocaine on the dopamine response evoked by either MFB or PPTg stimulation, recorded in either NAc shell or core. Results of this study support the concept that stress-induced activation of KOR by endogenous dynorphin opioids may enhance the rewarding valence of drugs of abuse by potentiating the evoked dopamine response. PMID:24971603

Ehrich, Jonathan M; Phillips, Paul E M; Chavkin, Charles

2014-12-01

359

Effect of interstimulus interval and age on cortical auditory evoked potentials in 10-22-week-old infants.  

PubMed

This study compares cortical auditory evoked potentials (CAEPs) at different interstimulus intervals (ISIs) in infants to determine the impact of stimulus rate on wave morphology. Infant CAEPs are dominated by a positive peak P1. We hypothesized that infant CAEPs would be more adult-like at longer ISI with P1, followed by negativity (labelled N450). Participants were 10 typically developing infants aged 10-13 weeks (N=4) and 20-22 weeks (N=6). CAEPs were measured in one recording session for /da/ in quiet at 55 dB SPL for ISIs of 910, 1820, 3640 and 4550 ms in a randomized order. Recordings were complete at each ISI for 7-10 infants. Seven infants who completed all testing in quiet were also tested in continuous white noise (+5 dB signal-to-noise ratio) for the shortest ISI. P1 was observable in all infants; N450 was only present in the older infants. There appeared to be no ISI effect for younger or older infants, which is not consistent with ISI findings for adults and older children. The presence of N450 in the older infants only suggests that cortical maturational differences are evident in speech-evoked CAEPs in young infants. There were minimal effects of noise on P1 latency and amplitude. Results suggest different effects of ISI for very young infants than those observed in older infants and children. CAEPs are being used to measure hearing aid effectiveness in young infants and hence it is imperative that the effects of factors such as ISI are better understood. PMID:24323125

Sharma, Mridula; Johnson, Patrice K H; Purdy, Suzanne C; Norman, Farah

2014-03-01

360

A Machine Learning Approach for Distinguishing Age of Infants Using Auditory Evoked Potentials  

E-print Network

in the understanding of the development of the human brain. A potential clinical use for the proposed methodology the state of brain development of infants, based on their event related potentials (ERPs) in response the state of brain development of infants. #12;3 Significance: This study is of fundamental scientific

Reilly, James P.

361

Adult Brainstem Gliomas  

PubMed Central

Brainstem gliomas are uncommon in adults and account for only 1%–2% of intracranial gliomas. They represent a heterogeneous group of tumors that differ from those found in their pediatric counterparts. In adults, a low-grade phenotype predominates, which is a feature that likely explains their better prognosis compared to that in children. Because biopsies are rarely performed, classifications based on the radiological aspect of magnetic resonance imaging results have been proposed to establish treatment strategies and to determine outcomes: (a) diffuse intrinsic low-grade, (b) enhancing malignant glioma, (c) focal tectal gliomas, and (d) exophytic gliomas. Despite significant advances in neuroradiology techniques, a purely radiological classification remains imperfect in the absence of a histological diagnosis. Whereas a biopsy may often be reasonably avoided in the diffuse nonenhancing forms, obtaining histological proof seems necessary in many contrast-enhanced brainstem lesions because of the wide variety of differential diagnoses in adults. Conventional radiotherapy is the standard treatment for diffuse intrinsic low-grade brainstem gliomas in adults (the median survival is 5 years). In malignant brainstem gliomas, radiotherapy is the standard treatment. However, the possible benefit of combined radiotherapy and chemotherapy (temozolomide or other agents) has not been thoroughly evaluated in adults. The role of anti-angiogenic therapies in brainstem gliomas remains to be defined. A better understanding of the biology of these tumors is of primary importance for identifying homogeneous subgroups and for improving therapy options and outcomes. PMID:22382458

Reyes-Botero, German; Mokhtari, Karima; Martin-Duverneuil, Nadine; Delattre, Jean-Yves

2012-01-01

362

Long-Term Potentiation and Evoked Spike Responses in the Cingulate Cortex of Freely Mobile Rats  

Microsoft Academic Search

Long-term potentiation of synaptic efficiency is regarded as a major candidate for the role of the physiological mechanism of long-term memory. However, the limited development of concepts of the cellular and subcellular characteristics of the induction of long-term potentiation in animals in conditions of free behavior does not correspond to the importance of this question. The present study was undertaken

A. G. Gorkin; K. G. Reymann; Yu. I. Aleksandrov

2003-01-01

363

Spinocerebellar ataxia type 4 (SCA4): Initial pathoanatomical study reveals widespread cerebellar and brainstem degeneration.  

PubMed

Spinocerebellar ataxia type 4 (SCA4), also known as 'hereditary ataxia with sensory neuropathy', represents a very rare, progressive and untreatable form of an autosomal dominant inherited cerebellar ataxia (ADCA). Due to a lack of autopsy cases, no neuropathological or clinicopathological studies had yet been performed in SCA4. In the present study, the first available cerebellar and brainstem tissue of a clinically diagnosed and genetically-confirmed German SCA4 patient was pathoanatomically studied using serial thick sections. During this systematic postmortem investigation, along with an obvious demyelinization of cerebellar and brainstem fiber tracts we observed widespread cerebellar and brainstem neurodegeneration with marked neuronal loss in the substantia nigra and ventral tegmental area, central raphe and pontine nuclei, all auditory brainstem nuclei, in the abducens, principal trigeminal, spinal trigeminal, facial, superior vestibular, medial vestibular, interstitial vestibular, dorsal motor vagal, hypoglossal, and prepositus hypoglossal nuclei, as well as in the nucleus raphe interpositus, all dorsal column nuclei, and in the principal and medial subnuclei of the inferior olive. Severe neuronal loss was seen in the Purkinje cell layer of the cerebellum, in the cerebellar fastigial nucleus, in the red, trochlear, lateral vestibular, and lateral reticular nuclei, the reticulotegmental nucleus of the pons, and the nucleus of Roller. In addition, immunocytochemical analysis using the anti-polyglutamine antibody 1C2 failed to detect any polyglutamine-related immunoreactivity in the central nervous regions of this SCA4 patient studied. In view of the known functional role of affected nuclei and related fiber tracts, the present findings not only offer explanations for the well-known disease symptoms of SCA4 patients (i.e. ataxic symptoms, dysarthria and somatosensory deficits), but for the first time help to explain why diplopia, gaze-evoked nystagmus, auditory impairments and pathologically altered brainstem auditory evoked potentials, saccadic smooth pursuits, impaired somatosensory functions in the face, and dysphagia may occur during the course of SCA4. Finally, the results of our immunocytochemical studies support the concept that SCA4 is not a member of the CAG-repeat or polyglutamine diseases. PMID:16362839

Hellenbroich, Y; Gierga, K; Reusche, E; Schwinger, E; Deller, T; de Vos, R A I; Zühlke, C; Rüb, U

2006-07-01

364

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

PubMed Central

Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulation and by conducting a source analysis of the resulting evoked potentials of short and long latency. Ten healthy, right-handed subjects were recruited and evoked potentials were recorded to both left- and right-ear sound stimulation, above and below vestibular threshold. Below VEMP threshold, typical AEPs were recorded, consisting of mid-latency (MLR) waves Na and Pa followed by long latency AEPs (LAEPs) N1 and P2. In the supra-threshold condition, the expected changes in morphology were observed, consisting of: (1) short-latency vestibular evoked potentials (VsEPs) which have no auditory correlate, i.e. the ocular VEMP (OVEMP) and inion response related potentials; (2) a later deflection, labelled N42/P52, followed by the LAEPs N1 and P2. Statistical analysis of the vestibular dependent responses indicated a contralateral effect for inion related short-latency responses and a left-ear/right-hemisphere advantage for the long-latency responses. Source analysis indicated that the short-latency effects may be mediated by a contralateral projection to left cerebellum, while the long-latency effects were mediated by a contralateral projection to right cingulate cortex. In addition we found evidence of a possible vestibular contribution to the auditory T-complex in radial temporal lobe sources. These last results raise the possibility that acoustic activation of the otolith organs could potentially contribute to auditory processing. PMID:24699384

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

2014-01-01

365

Brainstem ischemia and preeclampsia.  

PubMed

Diffuse neurological manifestations of preeclampsia are due to endothelial involvement that lead to ischemia, hemorrhage, or edema. We analyzed clinical and radiological features and the course of brainstem ischemic strokes in a preeclampsia patient. We report a case of severe preeclampsia in a 30-year-old woman who was admitted 10 hr after a vaginal delivery at home. The pregnancy was at 39 wk, with no prenatal care. At her admission, she was conscious, and she had tetraparesia, swinging deep tendon reflex testing, drowsiness, and dysarthria; the BP was at 160/100 mmHg and 4 + proteinuria; magnetic resonance imaging revealed brainstem ischemic stroke. The evolution was favorable with symptomatic treatment. The patient was discharged on the 16th day; 2 months later she had a normal recovery. Brainstem strokes are rare. They are frequently due to hemorrhage; sometimes, they can also be ischemic. Their course is favorable. PMID:15617626

Housni, Brahim; Bayad, Rachida; Cherkab, Rachid; Salmi, Saďd; Miguil, Mohamed

2004-01-01

366

Mechanisms of Selective Attention during Competitive Discrimination of Visual and Auditory Verbal Information: Positron Emission Tomography and Cortical Evoked Potential Studies  

Microsoft Academic Search

The mechanisms of selective verbal attention were studied under conditions of simultaneous delivery of speech signals via the visual and auditory channels. The investigation was based on the comparison and synthesis of data obtained by two methods: positron emission tomography (PET) and brain evoked potentials (EPs). A new approach was developed: complementary tasks were constructed in such a way that,

S. V. Medvedev; M. S. Rudas; S. V. Pakhomov; A. M. Ivanitskii; I. R. Il'yuchenok; G. A. Ivanitskii

2003-01-01

367

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

EPA Science Inventory

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

368

DEPRESSION OF THE PHOTIC AFTER DISCHARGE OF FLASH EVOKED POTENTIALS BY PHYSOSTIGMINE, CARBARYL AND PROPOXUR AND THE RELATIONSHIP TO INHIBITION OF BRAIN CHOLINESTERASE  

EPA Science Inventory

The effects of N-methyl carbamate pesticides on the photic after discharge (PhAD) of flash evoked potentials (FEPs) and the relationship between inhibition of brain cholinesterase (ChE) activity and the PhAD were evaluated. FEPs were recorded in Long Evans rats treated with physo...

369

Neuropathies of the optic nerve and visual evoked potentials with special reference to color vision and differential light threshold measured with the computer perimeter OCTOPUS  

Microsoft Academic Search

The contrast evoked potentials (VEPs) to different check sizes were recorded in about 200 cases of discrete optic neuropathies (ON) of different origin. Differential light threshold (DLT) was tested with the computer perimeter OCTOPUS. Saturated and desaturated tests were applied to evaluate the degree of acquired color vision deficiency. Delayed VEP responses are not confined to optic neuritis (RBN) alone

Hannes Wildberger

1984-01-01

370

Reflection of an Orienting Reflex in the Phases of Evoked Potentials in the Rabbit Visual Cortex and Hippocampus during Substitution of Stimulus Intensity  

Microsoft Academic Search

Experiments on conscious rabbits were performed using the oddball paradigm, in which a rare (deviant) and common (standard) stimuli were of the same color but different intensities. Deviant stimuli were of lesser intensity. Recordings were made of evoked potentials induced by series of uniform deviant stimuli (without using standard stimuli), which were presented at the beginning and end of stimulation.

V. B. Polyanskii; D. V. Evtikhin; E. N. Sokolov

2004-01-01

371

Are somatosensory evoked potential recording and magnetic resonance imaging useful for evaluating the risk of neurologic compromise in rheumatoid arthritis patients with atlantoaxial subluxation?  

PubMed

The objective of this study was to determine whether early somatosensory evoked potential recording and/or magnetic resonance imaging are helpful for evaluating and monitoring the risk of neurologic compromise in rheumatoid arthritis patients. Thirty-seven patients with definite rheumatoid arthritis were studied, including 18 with atlantoaxial subluxation. A physical examination, roentgenograms of the cervical spine, early somatosensory evoked potential recording at all four limbs and magnetic resonance imaging of the cervical spine were done in each case. Alterations in somatosensory evoked potentials and magnetic resonance imaging evidence of compression of the medulla oblongata or spinal cord were found in similar proportions of patients with and without atlantoaxial subluxation. These results support the view that physical findings and changes on plain films of the cervical spine are the most reliable data for evaluating and monitoring the risk of neurologic damage in patients with atlantoaxial subluxation. Somatosensory evoked potential studies and magnetic resonance imaging should be reserved for those cases in which physical and roentgenographic data cannot be collected in a satisfactory manner and for patients who are included in study protocols that require accurate evaluation of lesions. PMID:8938867

Cartry, O; Collet, P; Convers, P; Barral, F G; Michel, D; Alexandre, C

1996-10-01

372

Estimating and Testing the Sources of Evoked Potentials in the Brain.  

ERIC Educational Resources Information Center

The source of an event-related brain potential (ERP) is estimated from multivariate measures of ERP on the head under several mathematical and physical constraints on the parameters of the source model. Statistical aspects of estimation are discussed, and new tests are proposed. (SLD)

Huizenga, Hilde M.; Molenaar, Peter C. M.

1994-01-01

373

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

ERIC Educational Resources Information Center

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

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

2010-01-01

374

Motor evoked potentials to magnetic stimulation: technical considerations and normative data from 50 subjects  

Microsoft Academic Search

Magnetic stimulation of the brain and cervical and lumbar spinal roots was performed on 50 healthy volunteers. Compound muscle action potentials (CMAPs) were recorded from biceps brachii, abductor digiti minimi (ADM), rectus femoris and tibiahs anterior (TA). We assessed central conduction times by subtraction of peripheral from central latencies and compared results using either spinal root stimulation or the F-wave

A. Furby; J. L. Bourriez; J. M. Jacquesson; F. Mounier-Vehier; J. D. Guieu

1992-01-01

375

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

PubMed Central

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

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

2014-01-01

376

Precise temporal association between cortical potentials evoked by motor imagination and afference induces cortical plasticity.  

PubMed

In monkeys, the repeated activation of somatosensory afferents projecting onto the motor cortex (M1) has a pivotal role in motor skill learning. Here we investigate if sensory feedback that is artificially generated at specific times during imagination of a dorsiflexion task leads to reorganization of the human M1. The common peroneal nerve was stimulated to generate an afferent volley timed to arrive during specific phases of the cortical potential generated when a movement was imagined (50 repetitions). The change in the output of M1 was quantified by applying single transcranial magnetic stimuli to the area of M1 controlling the tibialis anterior muscle. The results demonstrated that the concomitance between the cognitive process of movement (motor imagination) and the ascending volley due to the peripheral nerve stimulation can lead to significant increases in cortical excitability. These increases were critically dependent on the timing between the peripherally generated afferent volley and the cortical potential generated during the imagined movement. Only if the afferent volley arrived during the peak negative deflection of the potential, were significant alterations in motor cortical output attained. These results demonstrate that an artificially generated signal (the peripheral afferent volley) can interact with a physiologically generated signal in humans leading to plastic changes within the M1, the final output stage for movement generation within the human brain. The results presented may have implications in systems for artificially inducing cortical plasticity in patients with motor impairments (neuromodulation). PMID:22250210

Mrachacz-Kersting, Natalie; Kristensen, Signe Rom; Niazi, Imran Khan; Farina, Dario

2012-04-01

377

Direct noninvasive monitoring of spinal cord motor function during thoracic aortic occlusion: use of motor evoked potentials.  

PubMed

Spinal cord monitoring during thoracic aneurysmectomy by somatosensory evoked potentials has been criticized for its failure to measure anterior (motor) spinal cord function. We have developed a clinically applicable, noninvasive technique for intraoperative monitoring of motor evoked potentials (MEP), which allows direct functional assessment of spinal cord motor tracts during thoracic aortic occlusion. Twelve dogs underwent continuous intraoperative monitoring of MEP before, during, and after thoracic aortic cross-clamping. Motor tract response to noninvasive cord stimulation (5 to 10 mA, 0.02 msec, 4.3 H2) was recorded by subcutaneous electrodes placed along the length of the spine (T-10, L-1, and L-4). Six animals (group I) subjected to aortic cross-clamping alone demonstrated a characteristic time- and level-dependent deterioration and loss of MEP. Ischemic cord dysfunction (as determined by time from clamping to loss of MEP) progressed from the distal to the proximal cord (L-4 = 11.3 +/- 1.5 minutes; L-1 = 14.9 +/- 2.3 minutes; T-10 = 16.9 +/- 2.3 minutes; p less than 0.05 between all levels). Reperfusion of the distal aorta 20 minutes after clamping resulted in MEP return that progressed from the proximal (T-10) to distal (L-1 and L-4) cord. In another six animals (group II), distal perfusion (mean blood pressure = 95 mm Hg) was maintained for 1 hour after cross-clamping by left atrial-femoral artery bypass. Normal configuration and amplitude of MEP was maintained throughout the cross-clamping period. These data suggest that distinctive changes in MEP indicative of reversible ischemia of spinal cord motor tracts occur after aortic cross-clamping. Such ischemia begins in the most distal cord, exhibits upward progression with time, and can be prevented by maintenance of adequate distal aortic perfusion. Clinical use of MEP monitoring during thoracic aneurysmectomy may provide a method for intraoperative assessment of the adequacy of motor tract perfusion. PMID:3336122

Laschinger, J C; Owen, J; Rosenbloom, M; Cox, J L; Kouchoukos, N T

1988-01-01

378

Neuromodulation at single presynaptic boutons of cerebellar parallel fibers is determined by bouton size and basal action potential-evoked Ca transient amplitude  

PubMed Central

Most presynaptic terminals in the brain contain G-protein coupled receptors that function to reduce action potential-evoked neurotransmitter release. These neuromodulatory receptors, including those for glutamate, GABA, endocannabinoids and adenosine, exert a substantial portion of their effect by reducing evoked presynaptic Ca2+ transients. Many axons form synapses with multiple postsynaptic neurons, but it is unclear if presynaptic attenuation in these synapses is homogeneous, as suggested by population level Ca2+ imaging. We loaded Ca2+-sensitive dyes into cerebellar parallel fiber axons and imaged action potential-evoked Ca2+ transients in individual presynaptic boutons with application of three different neuromodulators and found that adjacent boutons on the same axon showed striking heterogeneity in their strength of attenuation. Moreover, attenuation was predicted by bouton size or basal Ca2+ response: smaller boutons were more sensitive to adenosine A1 agonist but less sensitive to CB1 agonist while boutons with high basal action potential-evoked Ca2+ transient amplitude were more sensitive to mGluR4 agonist. These results suggest that boutons within brief segment of a single parallel fiber axon can have different sensitivities towards neuromodulators and may have different capacities for both short-term and long-term plasticities. PMID:20007482

Zhang, Wei; Linden, David J.

2010-01-01

379

Consciousness and the Brainstem.  

ERIC Educational Resources Information Center

Summarizes a theoretical framework and set of hypotheses aimed at accounting for consciousness in neurobiological terms. Discusses the functional neuroanatomy of nuclei in the brainstem reticular formation. Notes that the views presented are compatible with the idea that the reticular formation modulates the electrophysiological activity of the…

Parvizi, Josef; Damasio, Antonio

2001-01-01

380

Linguistic status of timbre influences pitch encoding in the brainstem  

PubMed Central

The aim of this experiment is to assess the effects of the linguistic status of timbre on pitch processing in the brainstem. Brainstem frequency-following responses were evoked by the Mandarin high rising lexical tone superimposed on a native vowel quality ([i]), nonnative vowel quality ([ś]), and iterated rippled noise (non-speech). Results revealed that voice fundamental frequency magnitudes were larger when concomitant with a native vowel quality as compared to either nonnative vowel quality or non-speech timbre. Such experience-dependent effects suggest that subcortical sensory encoding of pitch interacts with timbre in the human brainstem. As a consequence, responses of the perceptual system can be differentially shaped to pitch patterns in relation to the linguistic status of their concomitant timbre. PMID:21934635

Krishnan, Ananthanarayan; Gandour, Jackson T.; Ananthakrishnan, Saradha; Bidelman, Gavin M.; Smalt, Christopher J.

2011-01-01

381

Motor evoked potentials to magnetic stimulation: technical considerations and normative data from 50 subjects.  

PubMed

Magnetic stimulation of the brain and cervical and lumbar spinal roots was performed on 50 healthy volunteers. Compound muscle action potentials (CMAPs) were recorded from biceps brachii, abductor digiti minimi (ADM), rectus femoris and tibialis anterior (TA). We assessed central conduction times by subtraction of peripheral from central latencies and compared results using either spinal root stimulation or the F-wave method. Side-to-side differences of total conduction time, peripheral conduction time and central conduction time (CCT) were measured and the effect of clockwise vs counterclockwise stimulations on latencies and sizes of CMAPs is emphasized. Amplitudes and areas of CMAPs were expressed as a percentage of the peripheral M response for ADM and TA. There was a positive correlation between CCT to the lumbosacral region and height, but not between the cervical region and height. No correlation was observed between genders and central conduction times, amplitudes or areas of CMAPs. PMID:1573419

Furby, A; Bourriez, J L; Jacquesson, J M; Mounier-Vehier, F; Guieu, J D

1992-03-01

382

A clinical case study of a Wolfram syndrome-affected family: pattern-reversal visual evoked potentials and electroretinography analysis.  

PubMed

Wolfram syndrome (WFS), or DIDMOAD, is a rare (1/100 000 to 1/770 000), progressive neurodegenerative disorder. In its early stages, it is characterized by insulin-dependent diabetes mellitus, optic atrophy and loss of sensorineural hearing-this is followed by diabetes insipidus, progressive neurological abnormalities and other endocrine abnormalities, which occur in later years. The aim of this study was to report on the clinical and electrophysiological findings from a family with the WFS1 mutation. The five family members were subjected to a complete ophthalmic examination, which included a flash full-field electroretinogram and pattern-reversal visual evoked potentials (PVEPs) performed according to ISCEV standards. Optic atrophy was confirmed in two homozygotic patients, where P100 latencies were significantly delayed-up to 146 ms in PVEP. P100 latencies were normal in the three heterozygotic patients we examined. Curve morphology abnormalities were observed in all five patients we examined. No literature describing the morphology of PVEP in Wolfram syndrome patients was found. In flash electroretinography, scotopic and photopic responses appeared in normal morphology and value. Diabetic retinopathy was not observed in the diabetes mellitus patients. PMID:22311385

Langwi?ska-Wo?ko, Ewa; Broniek-Kowalik, Karina; Szulborski, Kamil

2012-04-01

383

Effects of picture repetition on induced gamma band responses, evoked potentials, and phase synchrony in the human EEG.  

PubMed

Repeated experience with an object due to prior exposure to that object is commonly referred to as perceptual or repetition priming. One possible neuronal mechanism for repetition priming is 'repetition suppression' within a cell assembly coding the stimulus. Recently, induced gamma band responses (GBRs) were discussed as a possible physiological correlate of activity in such a cell assembly. The present EEG study was designed to investigate the modulation of induced GBRs when line drawings were presented either once or consecutively two or three times. Results showed a broad distribution of spectral gamma power and synchrony after initial picture presentation. Repeated presentations of the same picture led to a decrease of induced gamma power and less synchronized activity between distant electrode sites. The decrease of induced GBRs and synchrony after repeated picture presentations may be linked to a 'neural savings' mechanism within a cell assembly representing an object. Furthermore, the visual evoked potential, which was modulated by priming, showed a topographically different distribution compared to induced GBRs. PMID:11919002

Gruber, Thomas; Müller, Matthias M

2002-05-01

384

N1/P2 component of auditory evoked potential reflect changes of the brain serotonin biosynthesis in rats.  

PubMed

It is known that L-tryptophan stimulates serotonin synthesis in the brain and serotonergic neuronal activity. Also, the N1/P2 component of auditory evoked potential (AEP) is a good indicator of this activity in the auditory cortex. In the present work, we examined the effect of the L-tryptophan administration on electric activity of the auditory cortex recorded as the N1/P2 component of the AEP in adult male rats. The effect of serotonergic agonists or antagonists was also tested. The results showed that indeed L-tryptophan was able to induce a drastic change in auditory cortex electric activity, reducing very significantly the amplitude of the N1/P2 component of the AEP. Quipazine maleate had a similar effect as L-tryptophan and the serotonergic antagonist spiperone induced an increase in the N1/P2 amplitude. These results show how an isolated nutrient is able to induce significant changes in brain auditory cortical function, through stimulation of serotonin synthesis. Besides, they add evidence about the important role of serotonergic neurotransmission modulating sensory cortical activity and that the N1/P2 component of AEPs represent a useful noninvasive indicator of brain serotonin tone. PMID:16491646

Manjarrez, Gabriel; Hernandez, Edgar; Robles, Alejandro; Hernandez, Jorge

2005-08-01

385

Modification of motor activity, passive avoidance conditioning and evoked potentials by microinjections of picrotoxin in both caudate nuclei in cats.  

PubMed

Inhibition of movements is the result of the caudate nucleus (CN) activity. This action seems to be necessary for passive avoidance conditioning (PAC). Much data indicates that GABA has inhibitory effects in the CN. The present report provides further evidence for GABA inhibition in th4 CN. In cats, the acquisition session of a PAC response was carried out following the bilateral administration of 6 microgram of picrotoxin or saline in the CN. Twenty four hours later (1st test session) the animals were placed in the security compartment and remained there during 600 sec. In the second test, the cats injected with picrotoxin crossed to the other compartment while the subjects injected with saline did not move. Another series of acute experiments were also carried out. Evoked potentials (EP) were recorded in the CN produced by nucleus centralis medialis electrical stimulation. After picrotoxin application the first and second peaks, which could represent EPSPs, incraeased while the third peak, which could represent IPSPs, decreased. In conclusion, it seems that GABAergic intracaudate transmission maintains a lower level of neuronal discharges and probably participates in the maintenance of a PAC but not in its acquisition. PMID:531072

Vázquez, F; Téllez, C; De La Mora, P; Brust-Carmona, H

1979-11-01

386

Invariance of evoked-potential echo-responses to target strength and distance in an echolocating false killer whale  

NASA Astrophysics Data System (ADS)

Brain auditory evoked potentials (AEPs) were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target strength varied from -22 to -40 dB the distance varied from 1.5 to 6 m. All the records contained two AEP sets: the first one of a constant latency (transmission-related AEP) and a second one with a delay proportional to the distance (echo-related AEP). The amplitude of echo-related AEPs was almost independent of both target strength and distance, though combined variation of these two parameters resulted in echo intensity variation within a range of 42 dB. The amplitude of transmission-related AEPs was independent of distance but dependent on target strength: the less the target strength, the higher the amplitude. Recording of transmitted pulses has not shown their intensity dependence on target strength. It is supposed that the constancy of echo-related AEP results from variation of hearing sensitivity depending on the target strength and release of echo-related responses from masking by transmitted pulses depending on the distance. .

Supin, Alexander Ya.; Nachtigall, Paul E.; Au, Whitlow W. L.; Breese, Marlee

2005-06-01

387

The interaction of outgoing echolocation pulses and echoes in the false killer whale's auditory system: Evoked-potential study  

NASA Astrophysics Data System (ADS)

Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.

Supin, Alexander Ya.; Nachtigall, Paul E.; Au, Whitlow W. L.; Breese, Marlee

2004-06-01

388

Translumbar and Transsacral Motor Evoked Potentials: a novel test for spino-anorectal neuropathy in spinal cord injury  

PubMed Central

Introduction Spinal cord injury (SCI) causes anorectal problems, whose pathophysiology remains poorly characterized. A comprehensive method of evaluating spino-anorectal function is lacking. Aim To investigate the neuropathophysiology of bowel dysfunction in SCI by evaluating motor evoked potentials (MEP) of anus and rectum following trans-spinal magnetic stimulation and anorectal physiology. Methods Translumbar and transsacral magnetic stimulations, anorectal manometry and pudendal nerve latency (PNTML) were performed in 39 subjects with SCI and anorectal problems and 14 healthy controls and data were compared. MEPs were recorded with an anorectal probe containing bipolar ring electrodes. Results The MEPs were significantly prolonged (p<0.05) bilaterally, and at lumbar and sacral levels, and at rectal and anal sites in SCI subjects compared to controls. 95% of SCI subjects had abnormal MEPs; 53% had abnormal PNTML. All subjects with abnormal PNTML also demonstrated abnormal MEP, but 16/17 subjects with normal PNTML had abnormal MEP. Overall SCI patients had weaker anal sphincters (p<0.05), higher prevalence of dyssynergia (85%) and altered rectal sensation (82%). Conclusions Translumbar and transsacral MEPs revealed significant and hitherto undetected lumbo-sacral neuropathy in 90% of SCI subjects. Test was safe and provided neuropathophysiological information that could explain bowel dysfunction in SCI subjects. PMID:21266960

Tantiphlachiva, Kasaya; Attaluri, Ashok; Valestin, Jessica; Yamada, Thoru; Rao, Satish SC

2013-01-01

389

Algorithm for multi-curve-fitting with shared parameters and a possible application in evoked compound action potential measurements  

PubMed Central

Background Experimental results are commonly fitted by determining parameter values of suitable mathematical expressions. In case a relation exists between different data sets, the accuracy of the parameters obtained can be increased by incorporating this relationship in the fitting process instead of fitting the recordings separately. Methods An algorithm to fit multiple measured curves simultaneously was developed. The method accounts for parameters that are shared by some curves. It can be applied to either linear or nonlinear equations. Simulated noisy "measurement results" were created to compare the introduced method to the "straight forward" way of fitting the curves separately. Results The analysis of the simulated measurements confirm, that the introduced method yields more accurate parameters compared to the ones gained by fitting the measurements separately. Therefore it needs more computer time. As an example, the new fitting algorithm is applied to the measurements of the evoked compound action potentials (ECAP) of the auditory nerve: This leads to promising ideas to reduce artefacts generated by the measuring process. Conclusion The introduced fitting algorithm uses the relationship between multiple measurement results to increase the accuracy of the parameters. Its application in the field of ECAP measurements is promising and should be further investigated. PMID:16504064

Spitzer, Philipp; Zierhofer, Clemens; Hochmair, Erwin

2006-01-01

390

The steady-state visual evoked potential reveals neural correlates of the items encoded into visual working memory.  

PubMed

Visual working memory (VWM) capacity limitations are estimated to be ~4 items. Yet, it remains unclear why certain items from a given memory array may be successfully retrieved from VWM and others are lost. Existing measures of the neural correlates of VWM cannot address this question because they measure the aggregate processing of the entire stimulus array rather than neural signatures of individual items. Moreover, this cumulative processing is usually measured during the delay period, thereby reflecting the allocation of neural resources during VWM maintenance. Here, we use the steady-state visual evoked potential (SSVEP) to identify the neural correlates of individual stimuli at VWM encoding and test two distinct hypotheses: the focused-resource hypothesis and the diffuse-resource hypothesis, for how the allocation of neural resources during VWM encoding may contribute to VWM capacity limitations. First, we found that SSVEP amplitudes were larger for stimuli that were later remembered than for items that were subsequently forgotten. Second, this pattern generalized so that the SSVEP amplitudes were also larger for the unprobed stimuli in correct compared to incorrect trials. These data are consistent with the diffuse-resource view in which attentional resources are broadly allocated across the whole stimulus array. These results illustrate the important role encoding mechanisms play in limiting the capacity of VWM. PMID:25173712

Peterson, Dwight J; Gurariy, Gennadiy; Dimotsantos, Gabriella G; Arciniega, Hector; Berryhill, Marian E; Caplovitz, Gideon P

2014-10-01

391

Otoacoustic emissions, auditory evoked potentials and self-reported gender in people affected by disorders of sex development (DSD).  

PubMed

Both otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) are sexually dimorphic, and both are believed to be influenced by prenatal androgen exposure. OAEs and AEPs were collected from people affected by 1 of 3 categories of disorders of sex development (DSD) - (1) women with complete androgen insensitivity syndrome (CAIS); (2) women with congenital adrenal hyperplasia (CAH); and (3) individuals with 46,XY DSD including prenatal androgen exposure who developed a male gender despite initial rearing as females (men with DSD). Gender identity (GI) and role (GR) were measured both retrospectively and at the time of study participation, using standardized questionnaires. The main objective of this study was to determine if patterns of OAEs and AEPs correlate with gender in people affected by DSD and in controls. A second objective was to assess if OAE and AEP patterns differed according to degrees of prenatal androgen exposure across groups. Control males, men with DSD, and women with CAH produced fewer spontaneous OAEs (SOAEs) - the male-typical pattern - than control females and women with CAIS. Additionally, the number of SOAEs produced correlated with gender development across all groups tested. Although some sex differences in AEPs were observed between control males and females, AEP measures did not correlate with gender development, nor did they vary according to degrees of prenatal androgen exposure, among people with DSD. Thus, OAEs, but not AEPs, may prove useful as bioassays for assessing early brain exposure to androgens and predicting gender development in people with DSD. PMID:25038289

Wisniewski, Amy B; Espinoza-Varas, Blas; Aston, Christopher E; Edmundson, Shelagh; Champlin, Craig A; Pasanen, Edward G; McFadden, Dennis

2014-08-01

392

The Alaris auditory evoked potential monitor as an indicator of seizure inducibility and duration during electroconvulsive therapy: an observational study  

PubMed Central

Background Precise control of anesthetic depth during electroconvulsive therapy (ECT) is crucial because most intravenous anesthetics have anticonvulsant effects. In this study, we investigated the association between anesthetic depth measured by the Alaris auditory evoked potential index (AAI) and seizure inducibility and seizure duration during ECT. Methods Sixty-four ECTs were evaluated in 12 consecutive patients. General anesthesia was performed with a thiopental-based method. The relationship between the pre-ictal AAI, seizure activity and seizure duration was analyzed, and a possible threshold pre-ictal AAI to induce a seizure duration of at least 25 seconds was calculated. Results Forty-one of the 64 ECT stimuli successfully induced seizure activity that lasted longer than 25 seconds. Pre-ictal AAI was significantly correlated to seizure duration (r?=?0.54, p?

2014-01-01

393

Commanding a robotic wheelchair with a high-frequency steady-state visual evoked potential based brain-computer interface.  

PubMed

This work presents a brain-computer interface (BCI) used to operate a robotic wheelchair. The experiments were performed on 15 subjects (13 of them healthy). The BCI is based on steady-state visual-evoked potentials (SSVEP) and the stimuli flickering are performed at high frequency (37, 38, 39 and 40 Hz). This high frequency stimulation scheme can reduce or even eliminate visual fatigue, allowing the user to achieve a stable performance for long term BCI operation. The BCI system uses power-spectral density analysis associated to three bipolar electroencephalographic channels. As the results show, 2 subjects were reported as SSVEP-BCI illiterates (not able to use the BCI), and, consequently, 13 subjects (12 of them healthy) could navigate the wheelchair in a room with obstacles arranged in four distinct configurations. Volunteers expressed neither discomfort nor fatigue due to flickering stimulation. A transmission rate of up to 72.5 bits/min was obtained, with an average of 44.6 bits/min in four trials. These results show that people could effectively navigate a robotic wheelchair using a SSVEP-based BCI with high frequency flickering stimulation. PMID:23339894

Diez, Pablo F; Torres Müller, Sandra M; Mut, Vicente A; Laciar, Eric; Avila, Enrique; Bastos-Filho, Teodiano Freire; Sarcinelli-Filho, Mário

2013-08-01

394

Audiogram of a formerly stranded long-finned pilot whale (Globicephala melas) measured using auditory evoked potentials.  

PubMed

Long-finned pilot whales are highly social odontocetes found in temperate and subpolar regions. This species is particularly known for its interaction with fisheries as well as its mass strandings. Recent tagging work has provided some information about pilot whales in the wild but, even though they have been successfully kept in captivity, little is known about their sensory capabilities. This study investigates the hearing abilities of a rehabilitated 2 year old male long-finned pilot whale. A complete audiogram was collected using auditory evoked potential techniques that included measurements of nine frequencies from 4 to 100 kHz presented as sinusoidally amplitude-modulated tones. The results indicated that the region of best hearing was between 11.2 and 50 kHz and the subject had relatively poor high frequency hearing compared with other odontocete species. This study emphasizes the importance of collecting basic hearing measurements from new species, understanding diagnostic life histories as well as continuously increasing the sample size of audiometry measurements within and between odontocete species as animals become available. PMID:20802115

Pacini, A F; Nachtigall, P E; Kloepper, L N; Linnenschmidt, M; Sogorb, A; Matias, S

2010-09-15

395

Analysis of the EEG bispectrum, auditory evoked potentials and the EEG power spectrum during repeated transitions from consciousness to unconsciousness.  

PubMed

We have compared the auditory evoked potential (AEP) index (a numerical index derived from the AEP), 95% spectral edge frequency (SEF), median frequency (MF) and the bispectral index (BIS) during alternating periods of consciousness and unconsciousness produced by target-controlled infusions of propofol. We studied 12 patients undergoing hip or knee replacement under spinal anaesthesia. During periods of consciousness and unconsciousness, respective mean values for the four measurements were: AEP index, 60.8 (SD 13.7) and 37.6 (6.5); BIS, 85.1 (8.2) and 66.8 (10.5); SEF, 24.2 (2.2) and 18.7 (2.1); and MF, 10.9 (3.3) and 8.8 (2.0). Threshold values with a specificity of 100% for a state of unconsciousness were: AEP index, 37 (sensitivity 52%); BIS, 55 (sensitivity 15%); and SEF, 16.0 (sensitivity 9%). There was no recorded value for MF that was 100% specific for unconsciousness. Of the four measurements, only AEP index demonstrated a significant difference (P < 0.05) between all mean values 1 min before recovery of consciousness and all mean values 1 min after recovery of consciousness. Our findings suggest that of the four electrophysiological variables, AEP index was best at distinguishing the transition from unconsciousness to consciousness. PMID:9505777

Gajraj, R J; Doi, M; Mantzaridis, H; Kenny, G N

1998-01-01

396

Generating Visual Flickers for Eliciting Robust Steady-State Visual Evoked Potentials at Flexible Frequencies Using Monitor Refresh Rate  

PubMed Central

In the study of steady-state visual evoked potentials (SSVEPs), it remains a challenge to present visual flickers at flexible frequencies using monitor refresh rate. For example, in an SSVEP-based brain-computer interface (BCI), it is difficult to present a large number of visual flickers simultaneously on a monitor. This study aims to explore whether or how a newly proposed frequency approximation approach changes signal characteristics of SSVEPs. At 10 Hz and 12 Hz, the SSVEPs elicited using two refresh rates (75 Hz and 120 Hz) were measured separately to represent the approximation and constant-period approaches. This study compared amplitude, signal-to-noise ratio (SNR), phase, latency, scalp distribution, and frequency detection accuracy of SSVEPs elicited using the two approaches. To further prove the efficacy of the approximation approach, this study implemented an eight-target BCI using frequencies from 8–15 Hz. The SSVEPs elicited by the two approaches were found comparable with regard to all parameters except amplitude and SNR of SSVEPs at 12 Hz. The BCI obtained an averaged information transfer rate (ITR) of 95.0 bits/min across 10 subjects with a maximum ITR of 120 bits/min on two subjects, the highest ITR reported in the SSVEP-based BCIs. This study clearly showed that the frequency approximation approach can elicit robust SSVEPs at flexible frequencies using monitor refresh rate and thereby can largely facilitate various SSVEP-related studies in neural engineering and visual neuroscience. PMID:24918435

Nakanishi, Masaki; Wang, Yijun; Wang, Yu-Te; Mitsukura, Yasue; Jung, Tzyy-Ping

2014-01-01

397

Recording evoked potentials during deep brain stimulation: development and validation of instrumentation to suppress the stimulus artefact.  

PubMed

The clinical efficacy of deep brain stimulation (DBS) for the treatment of movement disorders depends on the identification of appropriate stimulation parameters. Since the mechanisms of action of DBS remain unclear, programming sessions can be time consuming, costly and result in sub-optimal outcomes. Measurement of electrically evoked compound action potentials (ECAPs) during DBS, generated by activated neurons in the vicinity of the stimulating electrode, could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulation parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1000 to 5000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 µs/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use of the ECAP as a feedback signal for the tuning of DBS parameters. PMID:22510375

Kent, A R; Grill, W M

2012-06-01

398

Recording evoked potentials during deep brain stimulation: development and validation of instrumentation to suppress the stimulus artefact  

NASA Astrophysics Data System (ADS)

The clinical efficacy of deep brain stimulation (DBS) for the treatment of movement disorders depends on the identification of appropriate stimulation parameters. Since the mechanisms of action of DBS remain unclear, programming sessions can be time consuming, costly and result in sub-optimal outcomes. Measurement of electrically evoked compound action potentials (ECAPs) during DBS, generated by activated neurons in the vicinity of the stimulating electrode, could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulation parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1000 to 5000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 µs/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use of the ECAP as a feedback signal for the tuning of DBS parameters.

Kent, A. R.; Grill, W. M.

2012-06-01

399

Recording evoked potentials during deep brain stimulation: development and validation of instrumentation to suppress the stimulus artefact  

PubMed Central

Deep brain stimulation (DBS) is an effective treatment for movement disorders, but the selection of stimulus parameters is a clinical burden and often yields sub-optimal outcomes for patients. Measurement of electrically evoked compound action potentials (ECAPs) during DBS could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulus parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1,000 to 5,000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 ?s/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use of the ECAP as a feedback signal for the tuning of DBS parameters. PMID:22510375

Kent, A R; Grill, W M

2012-01-01

400

[Changes in components of the auditory long-latency evoked potentials at different stages of the slow-wave sleep].  

PubMed

In accordance with the present views, during sleep, analysis of external stimuli continues at the subconscious level, because the need to estimate the biological significance of external stimuli in order to maintain a flexible contact of a sleeping subject with the environment persists during sleep. It is known that new components of the auditory evoked potentials (AEP) appear as sleep deepens. However, the common procedure of analysis of event-related potentials averaged for a group of subjects has some drawbacks because of the interindividual variability of the event-related potentials. Therefore, an additional analysis of the interindividual variability of the AEP shape and component structure can simplify the detection of individual components of group-averaged AEP at different stages of the slow-wave sleep. The AEPs were recorded in healthy volunteers (n = 26) during falling asleep in the evening from eight EEG derivations (F3, F4, C3, C4, P3, P4, O1, O2) in reference to a linked mastoid electrode. Computer-generated sound stimuli (50 ms-pulses with the frequency of 1000 Hz, 60 dB HL) were presented binaurally through earphones with interstimulus intervals of 20-40 s. Selective summation of AEPs for all the subjects was performed for each stage of the slow-wave sleep individually for each of the eight derivations. It was shown that the account made for interindividual variability of the AEP shape facilitated the identification of individual components of the group-averaged AEP typical of wakefulness (P1, N1, P300) and those which appeared during sleep onset and at different stages of the slow-wave sleep (P2, N350, P450, N550, N900). PMID:15828419

Dorokhov, V B; Verbitskaia, Iu S

2005-01-01

401

Attention to emotion: auditory-evoked potentials in an emotional choice reaction task and personality traits as assessed by the NEO FFI  

Microsoft Academic Search

Several studies suggest that attention to emotional content is related to specific changes in central information processing.\\u000a In particular, event-related potential (ERP) studies focusing on emotion recognition in pictures and faces or word processing\\u000a have pointed toward a distinct component of the visual-evoked potential, the EPN (‘early posterior negativity’), which has\\u000a been shown to be related to attention to emotional

Verena Mittermeier; Gregor Leicht; Susanne Karch; Ulrich Hegerl; Hans-Jürgen Möller; Oliver Pogarell; Christoph Mulert

2011-01-01

402

Processing of emotional words measured simultaneously with steady-state visually evoked potentials and near-infrared diffusing-wave spectroscopy  

Microsoft Academic Search

BACKGROUND: Emotional stimuli are preferentially processed compared to neutral ones. Measuring the magnetic resonance blood-oxygen level dependent (BOLD) response or EEG event-related potentials, this has also been demonstrated for emotional versus neutral words. However, it is currently unclear whether emotion effects in word processing can also be detected with other measures such as EEG steady-state visual evoked potentials (SSVEPs) or

Leonie Koban; Markus Ninck; Jun Li; Thomas Gisler; Johanna Kissler

2010-01-01

403

Attention's grasp: early and late hand proximity effects on visual evoked potentials  

PubMed Central

Behavioral studies suggest that visual attention is biased toward stimuli in the region of space near the palm of the hand, but it is unclear whether this effect is universal or selective for goal/task-related stimuli. We examined event-related potentials (ERPs) using a visual detection task in which the hand was placed near or kept far from target and non-target stimuli that were matched for frequency and visual features to avoid confounding factors. Focusing on attention-sensitive ERP components, we found that P3 (350–450 ms) amplitudes were increased for Hand Near conditions for targets only, demonstrating a selective effect consistent with the P3's cross-modal and task-relevance influences. An N1 variant implicated in visuo-tactile integration (central Nd1; 120–190 ms) showed similar target-specific effects. P1 (80–110 ms) effects for target stimuli were also apparent, but may have applied to non-targets as well, which would be consistent with the P1's association with early, pre-categorical increases in sensory gain. Collectively, these findings suggest that by the time stimuli are categorized as relevant/irrelevant for action, the proprioceptive effects of the hand on visual attention are selective for goal/task-related stimuli. At the same time, hand proximity appears to bias attention early, starting with a facilitation of processing for perhaps any visual stimuli near the hand, and continuing with enhancements that are selective to those stimuli categorized as task-relevant. PMID:23874315

Reed, Catherine L.; Leland, David S.; Brekke, Benjamin; Hartley, Alan A.

2013-01-01

404

Functional Imaging of the Human Brainstem during Somatosensory Input and Autonomic Output  

PubMed Central

Over the past half a century, many investigations in experimental animal have explored the functional roles of specific regions in the brainstem. Despite the accumulation of a considerable body of knowledge in, primarily, anesthetized preparations, relatively few studies have explored brainstem function in awake humans. It is important that human brainstem function is explored given that many neurological conditions, from obstructive sleep apnea, chronic pain, and hypertension, likely involve significant changes in the processing of information within the brainstem. Recent advances in the collection and processing of magnetic resonance images have resulted in the possibility of exploring brainstem activity changes in awake healthy individuals and in those with various clinical conditions. We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity. More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension. Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens. PMID:24062670

Henderson, Luke A.; Macefield, Vaughan G.

2013-01-01