Science.gov

Sample records for brainstem evoked potentials

  1. Brainstem evoked potentials in panic disorder.

    PubMed Central

    Knott, V J; Bakish, D; Barkley, J

    1994-01-01

    Patient reports and laboratory tests support the notion that panic attacks are generated by stimulation of brainstem nuclei. Scalp-recorded brainstem auditory evoked potentials may serve as a unique measurement strategy for the noninvasive assessment of the role of brainstem functioning in panic disorder. Ipsilateral and contralateral BSAEP recordings were examined in response to separate left and right ear click stimulation in 28 patients with a diagnosis of panic disorder and in 18 normal controls. Latency measures did not differentiate between the patient and control groups but amplitudes of wave III and V were found to be larger in patients. These findings are discussed in relation to pathophysiological and neurochemical theories of panic and specific emphasis is placed on serotonergic function. PMID:7918353

  2. [Brainstem auditory evoked potentials in low and high risk newborns].

    PubMed

    Poblano, A; Mendiola-Bonaga, H; Valdez-Cárdenas, H; Tapia, O; Rios-Valles, A; Montes de Oca-Fernández, E; Fuentes-Aguirre, S; Aguilar, Y; Vidal, F

    1993-08-01

    Brainstem auditory evoked potentials (BAEP) were performed in a population of preterm infants of 32-34, 35-37 and 38-41 weeks of gestational age (GE) high risk newborns, and in 38-41 weeks GE low risk newborns. Statistical differences were found between both 38-41 weeks GE groups. High risk newborns showed longer latencies of waves III and V (P < 0.001), and I-III and I-V interwave intervals (P < 0.01). Our data show that auditory brainstem system suffer in high risk newborns. Results is discussed in relationship with other brainstem auditory evoked potentials studies in high risk newborns due it's clinical implications of present data. PMID:8357514

  3. Brainstem auditory evoked potentials among rubber factory workers.

    PubMed

    Tandon, O P; Gupta, P; Bhargava, S K; Chaswal, M

    1999-04-01

    The study was conducted on 27 rubber factory workers for the functional assessment of brainstem auditory pathway. Neurobehavioural questionnaire was administered to the workers and the personal sampler was used to evaluate the respirable particulate load inhaled per day of each worker along with qualitative analysis for PAH compounds. Evoked potential recording was carried out for brainstem auditory responses. Chest X-rays of workers exhibited varied abnormal features. Multiple regression analysis of data showed definite prolongation of latencies with increasing concentration of respirable particulate load though it was not statistically significant. Comparison with normative data indicated prolongation of latencies of rubber factory workers. PMID:10365313

  4. Diagnosis of deafness in a horse by brainstem auditory evoked potential

    PubMed Central

    Harland, Malte M.; Marshall, Arvle E.; Belknap, Ellen B.

    2006-01-01

    Abstract Deafness was confirmed in a blue-eyed, 3-year-old, overo paint horse by brainstem auditory evoked potential. Congenital inherited deafness associated with lack of facial pigmentation was suspected. Assessment of hearing should be considered, especially in paint horses, at the time of pre-purchase examination. Brainstem auditory evoked potential assessment is well tolerated and accurate. PMID:16579041

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

    PubMed Central

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

    2011-01-01

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

  6. Generators of the brainstem auditory evoked potential in cat. II. Correlating lesion sites with waveform changes.

    PubMed

    Melcher, J R; Guinan, J J; Knudson, I M; Kiang, N Y

    1996-04-01

    Brainstem regions involved in generating the brainstem auditory evoked potential (BAEP) were identified by examining the effects of lesions on the click-evoked BAEP in cats. An excitotoxin, kainic acid, was injected into various parts of the cochlear nucleus (CN) or into the superior olivary complex (SOC). The locations of the resulting lesions were correlated with the changes produced in the various extrema of the BAEP waveforms. The results indicate that: (1) the earliest BAEP extrema (P1, N1 (recorded between vertex and the earbar ipsilateral to the stimulus) and P1a, P1b, (vertex to contralateral earbar)) are generated by cells with somata peripheral to the CN; (2) P2 is primarily generated by posterior anteroventral CN (AVCNp) and anterior posteroventral CN (PVCNa) cells; (3) SOC, anterior anteroventral CN (AVCNa), AVCNp, and PVCNa cells are involved in generating P3; (4) AVCNa cells are the main CN cells involved in P4, N4, and P5 generation; (5) both ipsilateral and contralateral SOC cells have a role in generating monaurally evoked P4 and P5; and (6) P5 is generated by cells with characteristic frequencies below 10 kHz. From (2) and (4), it is clear that P2 and P4-P5 are generated by cells in distinct, parallel pathways. PMID:8735067

  7. Generators of the brainstem auditory evoked potential in cat. III: Identified cell populations.

    PubMed

    Melcher, J R; Kiang, N Y

    1996-04-01

    This paper examines the relationship between different brainstem cell populations and the brainstem auditory evoked potential (BAEP). First, we present a mathematical model relating the BAEP to underlying cellular activity. Then, we identify specific cellular generators of the click-evoked BAEP in cats by combining model-derived insights with key experimental data. These data include (a) a correspondence between particular brainstem regions and specific extrema in the BAEP waveform, determined from lesion experiments, and (b) values for model parameters derived from published physiological and anatomical information. Ultimately, we conclude (with varying degrees of confidence) that: (1) the earliest extrema in the BAEP are generated by spiral ganglion cells, (2) P2 is mainly generated by cochlear nucleus (CN) globular cells, (3) P3 is partly generated by CN spherical cells and partly by cells receiving inputs from globular cells, (4) P4 is predominantly generated by medial superior olive (MSO) principal cells, which are driven by spherical cells, (5) the generators of P5 are driven by MSO principal cells, and (6) the BAEP, as a whole, is generated mainly by cells with characteristic frequencies above 2 kHz. Thus, the BAEP in cats mainly reflects cellular activity in two parallel pathways, one originating with globular cells and the other with spherical cells. Since the globular cell pathway is poorly represented in humans, we suggest that the human BAEP is largely generated by brainstem cells in the spherical cell pathway. Given our conclusions, it should now be possible to relate activity in specific cell populations to psychophysical performance since the BAEP can be recorded in behaving humans and animals. PMID:8735068

  8. Generators of the brainstem auditory evoked potential in cat. I. An experimental approach to their identification.

    PubMed

    Melcher, J R; Knudson, I M; Fullerton, B C; Guinan, J J; Norris, B E; Kiang, N Y

    1996-04-01

    This paper is the first in a series aimed at identifying the cellular generators of the brainstem auditory evoked potential (BAEP) in cats. The approach involves (1) developing experimental procedures for making small selective lesions and determining the corresponding changes in BAEP waveforms, (2) identifying brainstem regions involved in BAEP generation by examining the effects of lesions on the BAEP and (3) identifying specific cell populations involved by combining the lesion results with electrophysiological and anatomical information from other kinds of studies. We created lesions in the lower brainstem by injecting kainic acid which is generally toxic for neuronal cell bodies but not for axons and terminals. This first paper describes the justifications for using kainic acid, explains the associated problems, and develops a methodology that addresses the main difficulties. The issues and aspects of the specific methods are generally applicable to physiological and anatomical studies using any neurotoxin, as well as to the present BAEP study. The methods chosen involved (1) measuring the BAEP at regular intervals until it reached a post-injection steady state and perfusing the animals with fixative shortly after the last BAEP recordings were made, (2) using objective criteria to distinguish injection-related BAEP changes from unrelated ones, (3) making control injections to identify effects not due to kainic acid toxicity, (4) verifying the anatomical and functional integrity of axons in lesioned regions, and (5) examining injected brainstems microscopically for cell loss and cellular abnormalities indicating dysfunction. This combination of methods enabled us to identify BAEP changes which are clearly correlated with lesion locations. PMID:8735066

  9. Brainstem auditory evoked potentials in children with low level cumulative lead exposure

    PubMed Central

    Alvarenga, Kátia F.; Morata, Thais C.; Lopes, Andréa Cintra; Feniman, Mariza Ribeiro; Corteletti, Lilian Cássia Bórnia Jacob

    2015-01-01

    Introduction Earlier studies have demonstrated an auditory effect of lead exposure in children,but information on the effects of low chronic exposures needs to be further elucidated. Objective To investigate the effect of low chronic exposures of the auditory system in childrenwith a history of low blood lead levels, using an auditory electrophysiological test. Methods Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6years, 8 months ± 3 years, 2 months). Results The mean time-integrated cumulative blood lead index was 12 g/dL (SD ± 5.7, range:2.433). All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I---III, III---V, and I---V, and the cumulative lead values. Conclusion No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area. PMID:25458254

  10. Auditory brainstem evoked potentials peak identification by finite impulse response digital filters.

    PubMed

    Pratt, H; Urbach, D; Bleich, N

    1989-01-01

    Linear phase finite impulse response (FIR) filtering can be used to differentiate auditory brainstem evoked potentials (ABEP) components. The power spectrum of ABEP at high intensities indicates that they contain 3 frequency bands that can be distinguished by applying appropriate digital filters with the following characteristics: up to 240 Hz (revealing slow components), 240-483 Hz (resulting in medium components) and above 500 Hz (leaving only fast components). The results using these filters, indicate that the medium components coincide with peaks I, III and V and that the slow filter results in a 'pedestal' whose peak coincides with peak V. These findings were used for automatic identification of ABEP peaks. A coincidence of the 'pedestal' peak with a medium component was sought and labelled peak V. The preceding medium peaks were labelled, in order of decreasing latency, III and I. Validation of this procedure was conducted on ABEP from normal subjects, using different stimulus rates and intensities, as well as from selected neurological patients with lesions affecting the brainstem. Provided the waveform included a 'pedestal', the results proved this procedure to be reliable and in very good agreement with manual identification and measurement of ABEP peaks. PMID:2803115

  11. Brainstem Auditory Evoked Potentials in Boys with Autism: Still Searching for the Hidden Truth

    PubMed Central

    VERVERI, Athina; VARGIAMI, Euthymia; PAPADOPOULOU, Vassiliki; TRYFONAS, Dimitrios; ZAFEIRIOU, Dimitrios

    2015-01-01

    Objective Brainstem auditory evoked potentials (BAEPs) have long been utilized in the investigation of auditory modulation and, more specifically, auditory brainstem functions in individuals with autism. Although most investigators have reported significant abnormalities, no single BAEPs pattern has yet been identified. The present study further delineates the BAEPs deficits among subjects with autism. Materials & Methods BAEPs were recorded in 43 male patients, aged 35104 months, who underwent standard evaluations after receiving a diagnosis of autism. The control group consisted of 43 age-matched typically developing boys. The study took place in a tertiary neurodevelopmental center over a period of two years. Results The mean values of all absolute and/or interpeak latencies were longer in patients when compared to controls, albeit the differences were not significant for any of the parameters. Prolonged or shortened absolute/interpeak latencies (control group mean 2.5SD) were unilaterally or bilaterally identified in 33% of patients, compared to 9% of controls. The most frequent findings included prolongation of absolute latencies I, V and III, followed by shortening of interpeak latency I-V. In addition, abnormalities (either shortening or prolongation) of absolute latencies I and V, as well as interpeak latency I-V, were significantly more common among patients. Taken together, BAEPs in 23% of patients were indicative of a clinically abnormal response in 32% of patients. Conclusion As can be easily concluded, BAEPs abnormalities characterize only a subset of subjects with autism, who may be important to identify clinically. The latter individuals may benefit from targeted intervention to utilize brainstem plasticity. PMID:26221159

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

    PubMed

    Shaw, N A

    1995-10-01

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

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

    PubMed

    Tarantino, V; Stura, M; Vallarino, R

    1988-01-01

    In order to study the various changes which occur in the waveform, latency and amplitude of the auditory brainstem evoked response (BSER) as a function of age, the authors recorded the BSER from the scalp's surface of 20 newborns and 50 infants, 3 months, 6 months, 1 year and 3 years old as well as from 20 normal adults. The data obtained show that the most reliable waves during the first month of life are waves I, III, V, which is often present even when other vertex-positive peaks are absent. The latencies of the various potential components decreased with maturation. Wave V, evoked by 90 dB sensation level clicks, changed in latency from 7, 12 msec at 1-4 weeks of age to 5,77 msec at 3 years of life. The auditory processes related to peripheral and central transmission were shown to mature at differential rates during the first period of life. By the 6th month, in fact, wave I latency had reached the adult value; in contrast, wave V latency did match that of the adult until approximately 1 year old. One obvious explanation for the age-related latency shift is progressive myelination of the auditory tract in infants, for this is know to occur. The authors conclude that the clinical application of this technique in paediatric patients couldn't provide reliable informations about auditory brain stem activity regardless of evaluation of the relationship between age and characteristics of BSER. PMID:3287352

  14. The effect of smoking on brainstem auditory evoked potentials in positive- and negative-symptom schizophrenia.

    PubMed

    Mubarak, A; Badawy, A

    2001-06-01

    Studying brainstem auditory evoked potentials (BAEPs) and comparing the specific waves in smokers vs nonsmokers in both positive- and negative-symptom schizophrenia may elucidate the role of smoking in information processing. BAEPs were recorded in 40 patients with schizophrenia; 20 had predominantly positive symptoms (10 smokers and 10 nonsmokers) and 20 had predominantly negative symptoms (10 smokers and 10 nonsmokers). The severity of positive and negative symptoms was assessed by scale of assessment of positive symptoms and scale of assessment of negative symptoms (SANS). The BAEP results were compared with 15 healthy control individuals matched with the patients by age, sex, and cultural background. The smokers with negative symptoms showed a significant increase in the alogia, summary, and composite scores of SANS as compared to the nonsmokers. Although, most of the BAEP abnormalities were among patients with positive symptoms. The effect of smoking on the BAEPs was only in patients with negative symptoms. We also studied the interaction between smoking factor (smokers vs nonsmokers) and group type (group with mostly positive symptoms vs group with mostly negative symptoms) on the BAEPs and found a significant difference only for the first-wave latency mainly on the right side (P=0.012). The absence of a significant effect of smoking on most of the parameters of the BAEPs on interaction with the group factor suggests that the effect of smoking on the BAEPs is more apparent when negative symptoms prevail. However, studies are warranted to substantiate this finding. PMID:15744214

  15. Power spectral analysis of normal and pathological brainstem auditory evoked potentials.

    PubMed

    Kamath, M V; Reddy, S N; Ghista, D N; Upton, A R

    1987-07-01

    The brainstem auditory evoked potential (BAEP) recording has become a powerful investigational tool in neurological diagnosis. The BAEPs of patients have different latencies and morphologies when compared to those of normals. In this paper the power spectra (PS) of BAEPs of 21 normals, 17 patients with multiple sclerosis (MS) and 12 patients with head injury (HI) computed by Blackman-Tukey (BT) and Maximum Entropy (ME) methods are examined for their frequency composition. Three major peaks appear at approximately 170 Hz, 520 Hz and 950 Hz in PS of normal BAEPs. The average power contained in the frequency bands spread around these frequency bands for BAEPs of patients differed significantly (P less than 0.05) from those of normal BAEPs. The peaks observed in ME spectra were found to match those computed using BT method. The model order for representing both normal and patient BAEPs is greater than 40 and data compression afforded by modelling the BAEPs is of the order of 5:1. PMID:3610376

  16. Alterations in brain-stem auditory evoked potentials among drug addicts

    PubMed Central

    Garg, Sonia; Sharma, Rajeev; Mittal, Shilekh; Thapar, Satish

    2015-01-01

    Objective: To compare the absolute latencies, the interpeak latencies, and amplitudes of different waveforms of brainstem auditory evoked potentials (BAEP) in different drug abusers and controls, and to identify early neurological damage in persons who abuse different drugs so that proper counseling and timely intervention can be undertaken. Methods: In this cross-sectional study, BAEP’s were assessed by a data acquisition and analysis system in 58 male drug abusers in the age group of 15-45 years as well as in 30 age matched healthy controls. The absolute peak latencies and the interpeak latencies of BAEP were analyzed by applying one way ANOVA and student t-test. The study was carried out at the GGS Medical College, Faridkot, Punjab, India between July 2012 and May 2013. Results: The difference in the absolute peak latencies and interpeak latencies of BAEP in the 2 groups was found to be statistically significant in both the ears (p<0.05). However, the difference in the amplitude ratio in both the ears was found to be statistically insignificant. Conclusion: Chronic intoxication by different drugs has been extensively associated with prolonged absolute peak latencies and interpeak latencies of BAEP in drug abusers reflecting an adverse effect of drug dependence on neural transmission in central auditory nerve pathways. PMID:26166594

  17. Effect of Prolonged Use of Mobile Phone on Brainstem Auditory Evoked Potentials

    PubMed Central

    Goyal, Darshan; Sharma, Rajiv; Arora, Khushdeep Singh

    2015-01-01

    Objectives Mobile phones are being widely used throughout the world. Electromagnetic waves generated from mobile phones have raised concerns as these may have adverse effects on human auditory system owing to the daily use of mobile phones. The purpose of current study was to evaluate the effects of long term mobile phone usage on auditory brainstem evoked responses (ABR). Materials and Methods A retrospective, cross-sectional, case control study was carried out in a tertiary care hospital. Total 100 healthy subjects aged 18 to 30 years of both the genders were selected, out of which 67 subjects were long-term GSM mobile phone users (using mobile phone for more than 1 year) and 33 were controls who were mobile phone non users. Both the groups were investigated for ABR and changes were studied in both the ears of cases and controls to ascertain the effects of electromagnetic exposure. Results No significant difference (p>0.05) was found in latencies, interpeak latencies and amplitudes of ABR waves between cases and controls. Conclusion Our study shows that long term usage of mobile phones does not affect propagation of electrical stimuli along the auditory nerve to auditory brainstem centres. PMID:26155473

  18. Speech Evoked Auditory Brainstem Response in Stuttering

    PubMed Central

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

    2014-01-01

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

  19. Human brainstem auditory-evoked potentials in deep experimental diving to pressures up to 62.5 bar.

    PubMed

    Lorenz, J; Athanassenas, G; Hampe, P; Plath, G; Wenzel, J

    1992-09-01

    The neural mechanisms underlying the high pressure neurologic syndrome (HPNS), which limit man's safe advance to extreme diving depths, are still unclear. This work was aimed at a better understanding of HPNS through study of brainstem auditory-evoked potentials (BAEP). BAEP were repeatedly recorded within 2 experimental chamber dives, Titan VIII (2 divers, maximum depth of 560 msw, compression time to bottom 109 h) and Titan XI (3 divers, maximum depth of 615 msw, compression time to bottom 240 h). Prolongation of the IV/V-complex occurred in 2 divers upon reaching 525 msw during Titan VIII compression and was accompanied by vestibular disturbances and amplitude increases of finger tremor. Both categories of changes--clinical signs and IV/V delay--gradually diminished during a 4-day stay at 545 msw, suggesting that they depended on excessive compression rates and insufficient acclimation time. Longer holding times at intermittent depths during Titan XI clearly reduced both HPNS symptoms and magnitude of prolongation of IV/V latencies. Wave I and wave III latency did not significantly change, pointing to a suppression of pontomesencephalic transmission. We infer that pressure suppresses synaptic transmission or triggers an increase of cortical or subcortical efferent inhibitory modulation of upper pontine and midbrain auditory afferents. Postdive controls revealed no persistent changes of BAEP measures in either the Titan VIII or XI divers. PMID:1355311

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

    PubMed

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

    2000-12-01

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

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

    PubMed Central

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

    2012-01-01

    Tinnitus or ringing of the ears is a subjective phantom sensation necessitating behavioral models that objectively demonstrate the existence and quality of the tinnitus sensation. The gap detection test uses the acoustic startle response elicited by loud noise pulses and its gating or suppression by preceding sub-startling prepulses. Gaps in noise bands serve as prepulses, assuming that ongoing tinnitus masks the gap and results in impaired gap detection. This test has shown its reliability in rats, mice, and gerbils. No data exists for the guinea pig so far, although gap detection is similar across mammals and the acoustic startle response is a well-established tool in guinea pig studies of psychiatric disorders and in pharmacological studies. Here we investigated the startle behavior and prepulse inhibition (PPI) of the guinea pig and showed that guinea pigs have a reliable startle response that can be suppressed by 15 ms gaps embedded in narrow noise bands preceding the startle noise pulse. After recovery of auditory brainstem response (ABR) thresholds from a unilateral noise over-exposure centered at 7 kHz, guinea pigs showed diminished gap-induced reduction of the startle response in frequency bands between 8 and 18 kHz. This suggests the development of tinnitus in frequency regions that showed a temporary threshold shift (TTS) after noise over-exposure. Changes in discharge rate and synchrony, two neuronal correlates of tinnitus, should be reflected in altered ABR waveforms, which would be useful to objectively detect tinnitus and its localization to auditory brainstem structures. Therefore, we analyzed latencies and amplitudes of the first five ABR waves at suprathreshold sound intensities and correlated ABR abnormalities with the results of the behavioral tinnitus testing. Early ABR wave amplitudes up to N3 were increased for animals with tinnitus possibly stemming from hyperactivity and hypersynchrony underlying the tinnitus percept. Animals that did not develop tinnitus after noise exposure showed the opposite effect, a decrease in wave amplitudes for the later waves P4–P5. Changes in latencies were only observed in tinnitus animals, which showed increased latencies. Thus, tinnitus-induced changes in the discharge activity of the auditory nerve and central auditory nuclei are represented in the ABR. PMID:22666193

  2. Auditory Brainstem Evoked Responses in Newborns with Down Syndrome

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  3. Auditory Brainstem Evoked Responses in Newborns with Down Syndrome

    ERIC Educational Resources Information Center

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

    2009-01-01

    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

  4. Evoked potentials and EEG in multiple sclerosis.

    PubMed

    Pakalnis, A; Drake, M E; Dadmehr, N; Weiss, K

    1987-10-01

    Thirteen patients with clinically definite multiple sclerosis (MS) were studied with electroencephalogram (EEG), magnetic resonance imaging (MRI), evoked potentials and cerebrospinal fluid (CSF) analysis. We attempted to correlate the findings with physical disability as defined by Kurtzke score and presence of dementia or seizures. More severe plaque disease on MRI and increased physical disability correlated significantly with abnormality on brain-stem auditory evoked potentials (BAEPs) while visual evoked potential (VEP) abnormality correlated only with MRI findings. No such correlation was found with the EEG. The close relationship between BAEP and MRI abnormalities probably reflects frequent involvement of brain-stem corticospinal pathways. PMID:2441967

  5. Evoked potentials in chronic inflammatory demyelinating polyneuropathy.

    PubMed

    Pakalnis, A; Drake, M E; Barohn, R J; Chakeres, D W; Mendell, J R

    1988-09-01

    Eighteen patients with chronic inflammatory demyelinating polyneuropathy were studied with evoked potentials to assess for evidence of central nervous system demyelination. Both visual and brain-stem auditory evoked responses were obtained, and the results were compared with magnetic resonance imaging (MRI). An evoked potential was abnormal in nine of 18 patients, five of whom had central nervous system evidence of demyelination by MRI. Evoked potentials identified four patients with probable anterior optic pathway involvement that was not demonstrable by MRI. These findings continue to support that chronic inflammatory demyelinating polyneuropathy is associated with a central demyelinating disorder and more importantly emphasize the possibility of a common pathogenic mechanism in central and peripheral nerve demyelination. PMID:2843153

  6. 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...

  7. Brainstem auditory evoked responses in partial and generalized seizures.

    PubMed

    Phillips, B; Drake, M E; Pakalnis, A; Bogner, J

    1990-07-01

    This study presents clinical neurophysiologic evidence of altered upper brainstem function in patients with generalized epilepsy who do not otherwise differ clinically from the general population. While the differences in absolute latencies are not great enough to support the use of BAERs in routine evaluation, this data does support experimental studies implicating brainstem structures in the pathophysiology of primary generalized epilepsy. The lack of evidence of brainstem involvement in complex partial seizures may suggest a mechanism of seizure spread that is not dependent upon primary brainstem pathology, or may indicate that any brainstem abnormality in epilepsy may involve areas not mediating transmission of auditory stimuli and therefore not assessed by BAERs. PMID:2114238

  8. [The use of brain stem auditory evoked potentials and electromyography in the monitoring of cranial nerves during skull base surgery].

    PubMed

    Szkiładź, E

    1997-01-01

    Cranial nerves and the brainstem are at risk of being injured during skull base operations. The result might be the patient's death or severe neurological deficits. Brainstem auditory evoked potential is an accepted method of intraoperative auditory nerve or brainstem monitoring. Other cranial nerves are monitored using electromyography and evoked muscle activity recorded from appropriated muscle groups. PMID:9380261

  9. Analysis of the click-evoked brainstem potentials in humans using high-pass noise masking. II. Effect of click intensity.

    PubMed

    Eggermont, J J; Don, M

    1980-12-01

    Derived narrow-band brainstem responses were obtained for click levels of 10--60 dB SL in normal hearing subjects. The amplitudes and latencies of the wave I, wave III, and wave V components in the derived BSER were studied as a function of click intensity. Characteristic differences were found between the input-output behavior of waves I and III on one hand and wave V on the other hand, especially for the low-frequency narrow bands (center frequencies of 0.5 and 1.0 kHz). While the wave I and wave III (peak-to-succeeding trough) amplitude showed a small (20--30 dB) dynamic range with saturation effects, the wave V amplitude continued to increase across the intensity range studied. At the high-frequency end (narrow-band center frequencies of 4 and 8 kHz), wave V also showed saturation. It is suggested that this difference across center frequency (place of origin along the cochlear partition) is responsible for the dominance of wave V at low-frequency stimulation (e.g., with tonebursts). The latencies of the three waves studied maintained their constant interwave delays across the observed intensity range in each narrow band. Quite large (up to 3.5 ms) increases in the narrow-band latencies were found for decreasing click levels; this is comparable in value with those for the unmasked BSER although the mechanism seems to be different. The major contribution to the BSER which determines its latencies, originates at 60 dB SL from the 8-kHz region but at low SL (10 and 20 dB) from the 2-kHz region. At these low intensity levels, the contribution from the apical part of the cochlea, however, is still of the same size as that from the high-frequency end. PMID:7462466

  10. Auditory evoked potentials in anxiety disorder.

    PubMed

    Drake, M E; Pakalnis, A; Phillips, B; Padamadan, H; Hietter, S A

    1991-04-01

    The pathophysiology of anxiety has received much recent attention. EEG findings in anxiety are nonspecific, and some changes in psychophysiological measures have been reported. We recorded short-latency brainstem auditory evoked potentials (BAEPs) and long-latency auditory event-related potentials (AEPs) in 12 patients with generalized anxiety disorder. All 12 patients had BAEP latencies within clinical norms, but I-V interpeak latencies were significantly longer in patients with anxiety than controls. N1, N2, P2, and P3 AEP components were within normal limits; N1 and P2 were reduced in amplitude in anxiety patients, but differences from controls were not significant. The BAEP findings may suggest altered brain-stem function in anxiety, which has been implied by biochemical studies of anxiety and depression. AEP differences may be related to difficulties in concentration and attention direction reported by anxious patients. PMID:2032349

  11. Stimulation of the brainstem reticular formation evokes locomotor activity in embryonic chicken (in ovo).

    PubMed

    Valenzuela, J I; Hasan, S J; Steeves, J D

    1990-10-01

    This study was designed to examine the period of embryonic chick development during which descending brainstem-spinal projections, originating from defined avian brainstem locomotor regions, become functionally active. Locomotor activity was examined using a new in ovo preparation for the focal electrical stimulation of embryonic brainstem locomotor regions. Embryos or hatchlings were anesthetized and mounted in a stereotaxic apparatus. Leg and wing muscle electromyographic (EMG) recordings were used to monitor any brainstem-stimulated motor activity. At present, we have been successful in demonstrating coordinated brainstem-evoked locomotion in embryos as early as embryonic day 15. The patterns of evoked locomotor activity were similar to locomotion evoked in hatchling chicks and were of 4 types: (1) alternating hindlimb movements ('stepping'), (2) synchronous (in-phase) hindlimb movements ('hatching'), (3) synchronous wing movements ('flapping'), and (4) simultaneous 'stepping' and 'flapping'. The cycle durations of evoked embryonic hindlimb movements are shorter than those observed for hatchling chicks. The present results are the first direct demonstration of functional connections between descending supraspinal neurons and spinal locomotor circuits at such an early stage of embryonic development. With modifications in technique, it may be possible to demonstrate functional connections at even earlier stages of embryonic development. PMID:2279325

  12. 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...

  13. Brainstem auditory evoked responses and ophthalmic findings in llamas and alpacas in Eastern Canada.

    PubMed

    Webb, Aubrey A; Cullen, Cheryl L; Lamont, Leigh A

    2006-01-01

    Seventeen llamas and 23 alpacas of various coat and iris colors were evaluated for: (1) deafness by using brainstem auditory evoked response testing; and (2) for ocular abnormalities via complete ophthalmic examination. No animals were deaf. The most common ocular abnormalities noted were iris-to-iris persistent pupillary membranes and incipient cataracts. PMID:16536233

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

    EPA Science Inventory

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

  15. Effect of Repetition Rate on Speech Evoked Auditory Brainstem Response in Younger and Middle Aged Individuals

    PubMed Central

    Kumar Neupane, Anuj; Gururaj, Krithika; Mehta, Garvita; Sinha, Sujeet Kumar

    2014-01-01

    Speech evoked auditory brainstem responses depicts the neural encoding of speech at the level of brainstem. This study was designed to evaluate the neural encoding of speech at the brainstem in younger population and middle-aged population at three different repetition rates (6.9, 10.9 and 15.4). Speech evoked auditory brainstem response was recorded from 84 participants (young participants=42, middle aged participants=42) with normal hearing sensitivity. The latency of wave V and amplitude of the fundamental frequency, first formant frequency and second formant frequency was calculated. Results showed that the latency of wave V was prolonged for middle-aged individuals for all three-repetition rates compared to the younger participants. The results of the present study also revealed that there was no difference in encoding of fundamental frequency between middle aged and younger individuals at any of the repetition rates. However, increase in repetition rate did affect the encoding of the fundamental frequency in middle-aged individuals. The above results suggest a differential effect of repetition rate on wave V latency and encoding of fundamental frequency. Further, it was noticed that repetition rate did not affect the amplitude of first formant frequency or second formant frequency in middle aged participants compared to the younger participants. PMID:26557355

  16. Evoked potentials in chronic n-hexane intoxication

    SciTech Connect

    Huang, C.C.; Chu, N.S. )

    1989-07-01

    Somatosensory, brainstem auditory and pattern-reversal visual evoked potentials (SEP, BAEP and PVEP) were studied in 5 patients with n-hexane polyneuropathy to determine if the CNS was affected. In SEPs, the median central conduction (N13-to-N20) was normal but the tibial central conduction (N22-to-P40) was delayed. The central conduction time (I-to-V interval) of the BAEP was also prolonged. However, the P100 latency of the PVEP was normal. The present data indicate that the spinal cord and the brainstem are primarily affected in chronic n-hexane intoxication.

  17. Somatosensory evoked potentials in syringomyelia.

    PubMed Central

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

    1986-01-01

    The two types of upper limb somatosensory evoked potential abnormality observed in nine patients with syringomyelia were reduced amplitude or absent cervical potentials and an abnormal central conduction time. Although this pattern of abnormalities resembles that observed in other intrinsic spinal cord lesions, it differs from peripheral nerve diseases and cervical radiculopathy in which the central conduction time is normal. PMID:3806117

  18. Auditory and Visual Evoked Potentials in Individuals with Organic and Cultural-Familial Mental Retardation.

    ERIC Educational Resources Information Center

    Zurron, Montserrat; Diaz, Fernando

    1995-01-01

    Brainstem, middle-latency, and long-latency auditory-evoked potentials and visual-evoked potentials were recorded for 66 individuals (ages 9-19) in the following comparison groups: cultural-familial mentally retarded, organically mentally retarded, and nonretarded. Target stimuli were evaluated more slowly by both groups with mental retardation.…

  19. Visual and auditory evoked potentials in migraine.

    PubMed

    Drake, M E; Pakalnis, A; Hietter, S A; Padamadan, H

    1990-01-01

    We recorded visual (VEP) and brainstem auditory (BAEP) evoked potentials in 50 patients with clinically diagnosed common migraine attended by visual obscuration or sensory symptoms but no neurologic deficit. VEPs were recorded from Oz, 01, and 02 referenced to Fz, with replication of 200 repetitions of 1.88 per second checkerboard stimuli subtending a 56 minute retinal arc. Analysis time was 250 ms., and filter band pass was 1-250 Hz. BAEPs utilized rarefaction stimulation at 70 dB SL, with 150-3,000 Hz filter band pass and 10 ms. analysis time. Two thousand averages were recorded and replicated from Cz-A1 and Cz-A2. VEP N1, P1 and N2 latencies were longer in migraine patients than in controls, and VEP amplitudes were minimally greater. No significant differences were found between patients and controls, however. BAEP I-V and III-V interpeak latencies were significantly prolonged in migraine patients, and the degree of prolongation was greater on the left. Neither VEPs nor BAEPs exceeded clinical norms in migraine patients. VEPs and BAEPs are likely to add little to the clinical assessment of headache patients. BAEP differences may indicate dysfunction of brainstem centers, possibly related to endorphin or serotonin neurotransmission, and possibly related to the pathogenesis of migraine. The left sided asymmetry has been described previously and is of uncertain significance, but may also support a central mechanism for migraine. PMID:2311571

  20. Infant temperament and the brainstem auditory evoked response in later childhood.

    PubMed

    Woodward, S A; McManis, M H; Kagan, J; Deldin, P; Snidman, N; Lewis, M; Kahn, V

    2001-07-01

    Brainstem auditory evoked responses (BAERs) were evaluated on 10-12-year-old children (N = 56) who had been classified as high or low reactive to unfamiliar stimuli at 4 months of age. BAER measurement was selected because high reactive infants tend to become inhibited or fearful young children, and adult introverts have a faster latency to wave V of the BAER than do extroverts. Children previously classified as high reactive at 4 months had larger wave V components than did low reactive children, a finding that possibly suggests greater excitability in projections to the inferior colliculus. The fact that a fundamental feature of brainstem activity differentiated preadolescent children belonging to two early temperamental groups supports the value of gathering physiological data in temperament research. PMID:11444488

  1. Toneburst-evoked auditory brainstem response in a leopard seal, Hydrurga leptonyx.

    PubMed

    Tripovich, J S; Purdy, S C; Hogg, C; Rogers, T L

    2011-01-01

    Toneburst-evoked auditory brainstem responses (ABRs) were recorded in a captive subadult male leopard seal. Three frequencies from 1 to 4 kHz were tested at sound levels from 68 to 122 dB peak equivalent sound pressure level (peSPL). Results illustrate brainstem activity within the 1-4 kHz range, with better hearing sensitivity at 4 kHz. As is seen in human ABR, only wave V is reliably identified at the lower stimulus intensities. Wave V is present down to levels of 82 dB peSPL in the right ear and 92 dB peSPL in the left ear at 4 kHz. Further investigations testing a wider frequency range on seals of various sex and age classes are required to conclusively report on the hearing range and sensitivity in this species. PMID:21303028

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

    PubMed Central

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

    2014-01-01

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

  3. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  4. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  5. Evidence from Auditory Nerve and Brainstem Evoked Responses for an Organic Brain Lesion in Children with Autistic Traits

    ERIC Educational Resources Information Center

    Student, M.; Sohmer, H.

    1978-01-01

    In an attempt to resolve the question as to whether children with autistic traits have an organic nervous system lesion, auditory nerve and brainstem evoked responses were recorded in a group of 15 children (4 to 12 years old) with autistic traits. (Author)

  6. Auditory evoked potentials in narcolepsy and sleep terrors.

    PubMed

    Drake, M E; Pakalnis, A; Padamadan, H; Hietter, S A

    1990-10-01

    Dysfunction of brainstem reticular activating centers has been suggested in some sleep disorders, including narcolepsy and sleep terrors. Previous studies have suggested normal brainstem auditory evoked potentials (BAEPs) in narcolepsy and enhancement of long-latency auditory event-related potentials (ERPs) in sleep deprivation and conditions of pathological somnolence. Sleep terrors have not to date been studied neurophysiologically. We recorded early latency BAEPs and long-latency auditory ERPs in 8 patients with narcolepsy and 5 individuals with sleep terrors, and compared them to 10 normal controls. Narcolepsy patients and controls did not differ significantly in absolute or interpeak latency of BAEPs. Sleep terror patients had significant prolongation relative to controls of III-V and I-V interpeak latencies. The N1, N2, and P3 AEP components were prolonged in latency in narcoleptic patients as compared to controls, while sleep terror patients did not differ from controls. No significant differences in amplitude were found. These findings suggest that a disturbance of integration of brainstem centers subserving wakefulness and sleep may play a role in the disordered arousal of sleep terrors, but suggest no specific abnormality in brainstem function in narcolepsy. The AEP changes in narcolepsy may be a manifestation of pathological sleepiness. PMID:2225468

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  8. Effect of anti-epileptic drug monotherapy and polypharmacy on visual and auditory evoked potentials.

    PubMed

    Drake, M E; Pakalnis, A; Padamadan, H; Hietter, S A; Brown, M

    1989-01-01

    Previous reports have suggested that some anticonvulsants may prolong somatosensory and auditory evoked potential latencies. We compared pattern-reversal visual and brainstem auditory evoked potentials in normal controls, patients on monotherapy, and patients taking polypharmacy. Visual evoked potential amplitudes were less in seizure patients, and P1 latencies were longer in epileptics on polypharmacy than controls. Absolute latencies of brainstem auditory evoked potentials were longer in polypharmacy patients than in controls or monotherapy patients. I-III, III-V, and I-V interpeak latencies were greater in polypharmacy patients than in those on monotherapy or controls. These findings suggest that anticonvulsants may affect conduction along visual and auditory pathways, and that antiepileptic drug polypharmacy and monotherapy may differ in their effects. PMID:2702959

  9. Auditory evoked potentials in borderline personality disorder.

    PubMed

    Drake, M E; Phillips, B B; Pakalnis, A

    1991-07-01

    Borderline personality disorder is an increasingly recognized condition and frequent management problem in psychiatric and nonpsychiatric practice. Paroxysmal changes in affect and behavior, high incidence of soft neurologic signs and frequent EEG alterations, and evidence of clinical response to antiepileptic drugs have suggested cerebral dysfunction, particularly involving the limbic system or reticular activating system. We recorded early latency brainstem auditory evoked potentials (BAEPs) and long-latency auditory event-related potentials (ERPs) in 20 patients fulfilling DSM-III-R criteria for this disorder. BAEPs were recorded from Cz to ipsilateral and contralateral ear reference, with rarefaction clicks presented at 11.1 per second and 70 dB SL. Two thousand averages were recorded and replicated for each ear, with filter band pass of 150-3000 Hz and 10 ms analysis time. ERPs utilized binaural stimulation with 1000 and 3000 Hz tones in an 80:20 ratio, with interstimulus interval 1.1 second, analysis time 1000 ms, and filter band pass 1-100 Hz. Two hundred averages were recorded and replicated from Cz with linked ear reference. No differences were evident in I-III, III-V, and I-V interpeak latencies between borderline patients and age-matched neurologically and audiologically normal controls. N1, P2, and N2 components of the AEPs were longer in latency and lower in amplitude in borderline patients, while P3 latency was longer and amplitude was attenuated in borderline patients as compared to controls. These findings may suggest differences from normals in attention maintenance and in limbic system function. PMID:1879058

  10. USE OF SENSORY EVOKED POTENTIALS IN TOXICOLOGY

    EPA Science Inventory

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

  11. Intraoperative evoked potential monitoring in acetabular surgery.

    PubMed

    Calder, H B; Mast, J; Johnstone, C

    1994-08-01

    The effectiveness of intraoperative sciatic nerve monitoring was evaluated for 88 consecutive patients undergoing open reduction and internal fixation for acetabular fractures. Intervention outcomes and pre and postoperative electrophysiologic status were compared to postoperative functional findings. Only 2% of the patients demonstrated iatrogenic sciatic nerve palsies. Functional and evoked potential findings were in agreement for 89% of the patients with postoperative palsies, while 26% of the functionally normal patients showed abnormal evoked potentials. Intervention occurred in 55 surgeries; 80% of interventions involved the peroneal nerve. Forty one of the 55 patients who had interventions based on evoked potential results showed recovery of responses to baseline. Of the 14 patients with incomplete intervention recovery, 11 showed impaired postoperative responses. Patients with preoperative evoked potential abnormalities did not show increased susceptibility to iatrogenic evoked potential changes. PMID:8050225

  12. The clinical significance of the P15 wave of the somatosensory evoked potential in tentorial herniation.

    PubMed

    Momma, F; Tsutsui, T; Symon, L; Ono, M

    1987-09-01

    Somatosensory evoked potentials (SEPs) to median nerve stimulation and auditory brainstem evoked potentials (BAEPs) were recorded in 16 comatose patients who had suffered transtentorial herniation (TH) due to intracranial haematoma, hydrocephalus or tumour. An attempt was made to correlate the changes in the N14-P15 component of the central conduction time (CCT) and the I-V interpeak latencies (IPLs) of the BAEP with the clinical severity of TH. The N14-P15 component was not affected in seven patients at the diencephalic or early third-nerve stage, and six of these seven showed normal I-V IPLs. All six patients at the late third-nerve/midbrain stage or worse, however, showed abnormalities in the N14-P15 components. Interestingly, five patients showed dissociation of SEP and BAEP abnormalities suggesting a differential sensitivity of the medial and lateral lemnisci in the brainstem to ischaemia and/or compression. All five patients in whom the P15 potential was absent on either side had a poor outcome and there was a correlation between the electrical failure in the N14-P15 component and the degree of brainstem damage caused by TH as assessed clinically. Reversible loss of the P15 potential by brainstem retraction has been shown in intraoperative SEP monitoring during aneurysm surgery. Prolonged compression of the upper brainstem seems to cause irreversible loss of the P15 which should be regarded as being due to irrecoverable brainstem dysfunction. PMID:2891061

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

    PubMed

    Piazza, S; Huynh, M; Cauzinille, L

    2014-06-01

    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

  14. [350m heliox saturated diving test--dynamic observation on hearing threshold, brainstem evoked response and acoustic impedance].

    PubMed

    Wang, L

    1991-01-01

    Four divers were investigated simulating a diving of 350m with saturated heliox under compression, performed in Jan 1989 at Navy Medical Institute. Changes in hearing threshold, brainstem evoked response and acoustic impedance were observed. The 4 divers experienced no tinnitus, hard of hearing and earache during compression and decompression. Objective examination showed loss of lower frequency range of hearing, that was due to the masking effect of the noise in the chamber. Changes in the wave--form and latency of brainstem evoked response were due to a change in sound wave transmission effected by the chamber pressure and a poor signal to noise ratio in the hyperbaric chamber of helium oxygen environment. All the changes were transient, after leaving the chamber, the hearing threshold and brainstem evoked response all returned to normal. Besides, there were no changes in the tympanogram, acoustic compliance and stapedius reflex before and after the experiment. Therefore the profile of compression and decompression in the experiment brought no harm to the divers' acoustic system; their Eustachian tubes, middle and inner ears functioned normally. PMID:1679643

  15. The effect of nimodipine on salicylate ototoxicity in the rat as revealed by the auditory evoked brain-stem response.

    PubMed

    Kay, I S; Davies, W E

    1993-01-01

    Experiments have been performed to investigate the ototoxic effects of sodium salicylate administration in anaesthetised rats as recorded by the auditory evoked brain-stem response (AEBR). Sodium salicylate (300 mg kg-1 i.p.) produced time-dependent increases in hearing threshold and decreases in the four principle peaks of the AEBR. Maximum responses were obtained at 4 h post-administration and were highly significant (P < 0.001). In a further series of experiments nimodipine, a calcium channel antagonist which has been suggested as a potential therapy for tinnitus, was administered at a dose of 2 mg kg-1 s.c. at the same time as sodium salicylate. This had no effect on the changes in hearing threshold. However, it did reduce the decrease in latencies of three of the four peaks of the AEBR, such that only the decrease in latency of the first peak was significantly different when compared to the pre-injection control latency (P < 0.01). We believe that these findings show specific neurophysiological correlates of salicylate ototoxicity. Since salicylate intoxication is used as the method for inducing tinnitus in animal models, the changes in the AEBR may provide an objective measure by which potential therapeutic intervention may be tested. PMID:8466750

  16. Purinergic receptors are involved in tooth-pulp evoked nocifensive behavior and brainstem neuronal activity

    PubMed Central

    2010-01-01

    Background To evaluate whether P2X receptors are involved in responses to noxious pulp stimulation, the P2X3 and P2X2/3 receptor agonist α,β-methyleneATP (α,β-meATP) was applied to the molar tooth pulp and nocifensive behavior and extracellular-signal regulated kinase (ERK) phosphorylation in trigeminal spinal subnucleus caudalis (Vc), trigeminal spinal subnucleus interpolaris (Vi), upper cervical spinal cord (C1/C2) and paratrigeminal nucleus (Pa5) neurons were analyzed in rats. Results Genioglossus (GG) muscle activity was evoked by pulpal application of 100 mM α,β-meATP and was significantly larger than GG activity following vehicle (phosphate-buffered saline PBS) application (p < 0.01). The enhanced GG muscle activity following 100 mM α,β-meATP was significantly reduced (p < 0.05) by co-application of 1 mM TNP-ATP (P2X1, P2X3 and, P2X2/3 antagonist). A large number of pERK-LI cells were expressed in the Vc, Vi/Vc, C1/C2 and Pa5 at 5 min following pulpal application of 100 mM α,β-meATP compared to PBS application to the pulp (p < 0.05). The pERK-LI cell expression and GG muscle activity induced by 100 mM α,β-meATP pulpal application were significantly reduced after intrathecal injection of the MAPK/ERK kinase (MEK) inhibitor PD 98059 and by pulpal co-application of 1 mM TNP-ATP (p < 0.05). Conclusions The present findings suggest that activation of P2X3 and P2X2/3 receptors in the tooth pulp is sufficient to elicit nociceptive behavioral responses and trigeminal brainstem neuronal activity. PMID:20860800

  17. Evoked potential application to study of echolocation in cetaceans

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  18. Multimodal evoked potentials and the ovarian cycle in young ovulating women.

    PubMed

    Resende, L A; Silva, M D; Impemba, F; Achôa, N B; Schelp, A O

    2000-06-01

    There is controversy over how hormonal conditions influence cerebral physiology. We studied pattern-shift visual evoked potentials (PS-VEP), brain stem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SSEV) in 20 female volunteers at different phases of the menstrual cycle (estrogen phase, ovulatory day and progesterone phase). Statistical analysis showed decreased latencies for P100 (PS-VEP), N19 and P22 (SSEV) waves in the progesterone phase compared with the estrogen phase. There was no significant difference between the estrogen and the ovulation day values. Comparing the three above stages, there were no significant differences in the brainstem auditory evoked potentials. The reduction of the latencies of the potentials generated in multisynaptic circuits provides the first consistent neurophysiological basis for a tentative comprehension of human pre-menstrual syndrome. PMID:10920401

  19. [Evoked potentials. Indications and diagnostic significance].

    PubMed

    Riffel, B; Stöhr, M; Reich, H; Delcker, A

    1986-07-15

    Visual, auditory and somatosensory evoked potentials are useful in the detection and localization of demyelinating lesions, which mainly cause a slowing of conduction and therefore a latency increase in the evoked potential. Primarily amplitude reductions or loss of the response are seen in partial or complete impulse conduction blocks due to a tumor e.g. Acoustic nerve tumors can be detected by AEP, orbit tumors or processes of the chiasm by VEP and spinal cord tumors by SEP. The use of evoked potentials for the evaluation of ophthalmologic disorders, for audiometry in children and for monitoring head-injured patients with coma have become a valuable aid to the physician too. PMID:3765650

  20. Auditory and visual evoked potentials during hyperoxia

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  1. Color Evoked Potentials in Adults and Infants.

    ERIC Educational Resources Information Center

    White, Carroll T.; And Others

    This paper discusses recent studies of the adult visual evoked potential (VEP) which have indicated that specific components of the complex waveform obtained are related to the three basic color processes, and that these components interact in ways that seem to agree with opponent-colors phenomena. The components identified as being related to the

  2. Far-field brainstem responses evoked by vestibular and auditory stimuli exhibit increases in interpeak latency as brain temperature is decreased

    NASA Technical Reports Server (NTRS)

    Hoffman, L. F.; Horowitz, J. M.

    1984-01-01

    The effect of decreasing of brain temperature on the brainstem auditory evoked response (BAER) in rats was investigated. Voltage pulses, applied to a piezoelectric crystal attached to the skull, were used to evoke stimuli in the auditory system by means of bone-conducted vibrations. The responses were recorded at 37 C and 34 C brain temperatures. The peaks of the BAER recorded at 34 C were delayed in comparison with the peaks from the 37 C wave, and the later peaks were more delayed than the earlier peaks. These results indicate that an increase in the interpeak latency occurs as the brain temperature is decreased. Preliminary experiments, in which responses to brief angular acceleration were used to measure the brainstem vestibular evoked response (BVER), have also indicated increases in the interpeak latency in response to the lowering of brain temperature.

  3. Multimodality evoked potentials: clinical applications and assessment of utility.

    PubMed

    Cohen, S N; Potvin, A; Syndulko, K; Pettler-Jennings, P; Potvin, J H; Tourtellotte, W W

    1982-01-01

    Visual evoked potentials (VEP), brain stem auditory evoked potentials (BAEP), somatosensory evoked potential (SEP), and long latency event related potentials (ERP) have been used to assess various aspects of the central nervous system. Multimodality evoked potential (MEP) testing uses a combination of these tests in the same clinical setting. In the diagnosis of multiple sclerosis and in the diagnosis of brain death, MEP testing has been shown to be more effective than any one evoked potential test used alone. In head trauma, MEP testing is an effective means of localization and prognostication. There are potential uses for MEP testing in Parkinson's Disease and uremia. PMID:7183366

  4. Evaluation of sensory evoked potentials in Long Evans rats gestationally exposed to mercury (Hg0) vapor.

    PubMed

    Herr, David W; Chanda, Sushmita M; Graff, Jaimie E; Barone, Stanley S; Beliles, Robert P; Morgan, Daniel L

    2004-11-01

    Mercury is known to alter neuronal function and has been shown to cross the placental barrier. These experiments were undertaken to examine if gestational exposure to mercury vapor (Hg(0)) would result in alterations in sensory neuronal function in adult offspring. Dams were exposed to 0 or 4 mg/m(3) Hg(0) for 2 h/day from gestational days 6-15. This exposure paradigm has been shown to approximate a maximal tolerated dose of Hg(0) for the dams. Between postnatal days 140-168, male and female offspring (one of each gender/dam) were examined using a battery of sensory evoked potentials. Peripheral nerve action potentials, nerve conduction velocity, somatosensory evoked responses (cortical and cerebellar), brainstem auditory evoked responses, pattern evoked potentials, and flash evoked potentials were quantified. Gestational exposure to 4 mg/m(3) Hg(0) did not significantly alter any of the evoked responses, although there was a suggestion of a decrease in compound nerve action potential (CNAP) amplitudes in male animals for the 3 mA stimulus condition. However, this possible change in CNAP amplitudes was not replicated in a second experiment. All evoked potentials exhibited predictable changes as the stimulus was modified. This shows conclusively that the evoked responses were under stimulus control, and that the study had sufficient statistical power to detect changes of these magnitudes. These results indicate that gestational exposure to 4 mg/m(3) Hg(0) did not result in changes in responses evoked from peripheral nerves, or the somatosensory, auditory, or visual modalities. PMID:15310857

  5. Analysis of evoked lumbosacral potentials in man.

    PubMed Central

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

    1978-01-01

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

  6. EEG and evoked potentials in episodic-dyscontrol syndrome.

    PubMed

    Drake, M E; Hietter, S A; Pakalnis, A

    1992-01-01

    The neurophysiologic correlates of explosive rage and violence are uncertain and controversial. We recorded 17-channel electroencephalograms (EEGs), brainstem auditory-evoked potentials (BAEPs), and long-latency auditory-event-related potentials (AEPs) in 23 patients with impulsive, aggressive and violent behavior satisfying criteria for episodic-dyscontrol syndrome. Most patients also satisfied criteria for intermittent explosive disorder, although some had had conduct disorders in childhood or had previously used psychoactive substances. Sixteen of 23 patients had normal EEGs, while 7 had diffuse or focal slowing not ascribable to drowsiness or the effects of medication. They differed significantly from 20 age-matched patients with headaches, of whom 1 had an abnormal EEG (chi 2 = 4.68, p < 0.05), and from 24 depressed patients, all of whose EEGs were normal (chi 2 = 4.83, p < 0.05). Patients and normal control subjects did not differ in BAEP latencies. N100 and P160 AEP amplitudes were lower in episodic-dyscontrol patients than in control, but the difference was not significant. These findings suggest that non-specific cerebral dysfunction and EEG changes may be associated with disordered impulse or behavior control. Episodic dyscontrol may be associated with other evidence of minimal brain dysfunction. PMID:1294892

  7. Long Latency Auditory Evoked Potentials during Meditation.

    PubMed

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

    2015-10-01

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

  8. Auditory evoked potentials in vertebrobasilar transient ischemic attacks.

    PubMed

    Drake, M E; Pakalnis, A; Padamadan, H; Hietter, S A

    1990-04-01

    Brainstem auditory evoked potentials (BAEPs) are affected by stroke or migraine in the vertebrobasilar arterial system. Some studies have reported BAEP changes in vertebrobasilar transient ischemic attacks (TIAs), but others have shown no alterations. We recorded BAEPs in 35 patients with TIAs in the vertebrobasilar system who did not have a stroke, other neurologic disease or significant hearing loss. Thirty patients were recorded after resolution of symptoms, while five individuals still had some resolving signs or symptoms. TIA patients as a group had longer interpeak latencies, but I-III, III-V, and I-V latencies were not significantly longer than in controls. Wave V was significantly longer in latency and lower in amplitude in TIA patients, however. The patients whose TIAs had resolved at absolute and interpeak latencies were within normal limits, but three of five had interpeak latencies at or above three standard deviations beyond the normal mean in the still symptomatic group. One of these was later tested and found to be within normal limits. BAEPs after subsidence of symptoms may add little to the evaluation of vertebrobasilar ischemia, but further AEP analysis may show more definitive differences of diagnostic use. The occasional BAEP abnormality during the resolving transient ischemia supports the recently suggested continuum between ischemia and infarction in the vertebrobasilar territory. PMID:2335045

  9. Resting Heart Rate and Auditory Evoked Potential

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  11. Contribution of Resolved and Unresolved Harmonic Regions to Brainstem Speech-Evoked Responses in Quiet and in Background Noise.

    PubMed

    Laroche, M; Dajani, H R; Marcoux, A M

    2011-05-10

    Speech auditory brainstem responses (speech ABR) reflect activity that is phase-locked to the harmonics of the fundamental frequency (F0) up to at least the first formant (F1). Recent evidence suggests that responses at F0 in the presence of noise are more robust than responses at F1, and are also dissociated in some learning-impaired children. Peripheral auditory processing can be broadly divided into resolved and unresolved harmonic regions. This study investigates the contribution of these two regions to the speech ABR, and their susceptibility to noise. We recorded, in quiet and in background white noise, evoked responses in twelve normal hearing adults in response to three variants of a synthetic vowel: i) Allformants, which contains all first three formants, ii) F1Only, which is dominated by resolved harmonics, and iii) F2&F3Only, which is dominated by unresolved harmonics. There were no statistically significant differences in the response at F0 due to the three variants of the stimulus in quiet, nor did the noise affect this response with the Allformants and F1Only variants. On the other hand, the response at F0 with the F2&F3Only variant was significantly weaker in noise than with the two other variants (p<0.001). With the response at F1, there was no difference with the Allformants and F1Only variants in quiet, but was expectedly weaker with the F2&F3Only variant (p<0.01). The addition of noise significantly weakened the response at F1 with the F1Only variant (p<0.05), but this weakening only tended towards significance with the Allformants variant (p=0.07). The results of this study indicate that resolved and unresolved harmonics are processed in different but interacting pathways that converge in the upper brainstem. The results also support earlier work on the differential susceptibility of responses at F0 and F1 to added noise. PMID:26557316

  12. Synaptically evoked dendritic action potentials in rat neocortical pyramidal neurons.

    PubMed

    Schwindt, P C; Crill, W E

    1998-05-01

    In a previous study iontophoresis of glutamate on the apical dendrite of layer 5 pyramidal neurons from rat neocortex was used to identify sites at which dendritic depolarization evoked small, prolonged Ca2+ spikes and/or low-threshold Na+ spikes recorded by an intracellular microelectrode in the soma. These spikes were identified as originating in the dendrite. Here we evoke similar dendritic responses by electrical stimulation of presynaptic elements near the tip of the iontophoretic electrode with the use of a second extracellular electrode. In 9 of 12 recorded cells, electrically evoked excitatory postsynaptic potentials (EPSPs) above a minimum size triggered all-or-none postsynaptic responses similar to those evoked by dendritic glutamate iontophoresis at the same site. Both the synaptically evoked and the iontophoretically evoked depolarizations were abolished reversibly by blockade of glutamate receptors. In all recorded cells, the combination of iontophoresis and an EPSP, each of which was subthreshold for the dendritic spike when given alone, evoked a dendritic spike similar to that evoked by a sufficiently large iontophoresis. In one cell tested, dendritic spikes could be evoked by the summation of two independent subthreshold EPSPs evoked by stimulation at two different locations. We conclude that the dendritic spikes are not unique to the use of glutamate iontophoresis because similar spikes can be evoked by EPSPs. We discuss the implications of these results for synaptic integration and for the interpretation of recorded synaptic potentials. PMID:9582218

  13. Deconvolution of the vestibular evoked myogenic potential.

    PubMed

    Lütkenhöner, Bernd; Basel, Türker

    2012-02-01

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

  14. Auditory evoked potential P50 as a predictor of neurologic outcome in resuscitated cardiac arrest patients.

    PubMed

    Takai, Nobuyuki; Oda, Shigeto; Sadahiro, Tomohito; Nakamura, Masataka; Watanabe, Eizo; Tateishi, Yoshihisa; Shinozaki, Koichiro; Nomura, Fumio; Mamada, Kenji

    2011-06-01

    In general, a prediction of neurologic outcome with respect to the resuscitated cardiac arrest patients has been performed by the auditory brainstem response and somatic evoked potential. The auditory brainstem response and somatic evoked potential are known as the predictors that correspond to neurologically poor outcome. None of the methods have been established to access neurologically good outcome. Because the hippocampal CA3 pyramidal cells have been widely used for pathophysiologic analyses concerning the hypoxic-ischemic encephalopathy and also the source of P50 components of the auditory evoked potential has been considered to be the hippocampal CA3 pyramidal cells, the authors assume that it might be possible that neurologic outcome in resuscitated cardiac arrest patients would be predicted by evaluating the P50 components. The purpose was to examine the P50 as a predictor of neurologic outcome in resuscitated cardiac arrest patients at the early stage from the onset. The P50 components of the auditory evoked potential are recorded in a conditioning-testing paradigm, that is, EEG responses to a pair of auditory stimuli with 500-millisecond interclick interval. In this study, subjects are 10 out-of-hospital cardiac arrest patients, 8 men and 2 women with a mean age of 54.8 years, who were admitted to the intensive care unit after the return of spontaneous circulation, with the presence of both the auditory brainstem response wave V and the somatic evoked potential wave N20 between the period from June 2008 to July 2009. It was found that the presence of the P50 at the early stage from the onset (days 5 ± 1.20) indicates good neurologic outcome, while the absence of the P50 implies poor prognosis. As to the auditory sensory gating of the P50, almost no reduction response to the second stimulus was observed. As a consequence, the evaluation of the P50 in resuscitated cardiac arrest patients would have a possibility to predict neurologically good outcome. PMID:21633256

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  16. Visual evoked potentials and dietary long chain polyunsaturated fatty acids in preterm infants.

    PubMed Central

    Faldella, G; Govoni, M; Alessandroni, R; Marchiani, E; Salvioli, G P; Biagi, P L; Spano, C

    1996-01-01

    The influence of dietary long chain polyunsaturated fatty acid (LCP) supply, and especially of docosahexaenoic acid (DHA), on evoked potential maturation, was studied in 58 healthy preterm infants using flash visual evoked potentials (VEPs), flash electroretinography (ERG), and brainstem acoustic evoked potentials (BAEPs) at 52 weeks of postconceptional age. At the same time, the fatty acid composition of red blood cell membranes was examined. The infants were fed on breast milk (n = 12), a preterm formula supplemented with LCP (PF-LCP) (n = 21), or a traditional preterm formula (PF) (n = 25). In the breast milk and PF-LCP groups the morphology and latencies of the waves that reflect the visual projecting system were similar; in the PF group the morphology was quite different and the wave latencies were significantly longer. This could mean that the maturation pattern of VEPs in preterm infants who did not receive LCP was slower. Moreover, a higher level of erythrocyte LCP, especially DHA, was found in breast milk and PF-LCP groups compared with the PF group. ERG and BAEP recordings were the same in all three groups. These results suggest that a well balanced LCP supplement in preterm formulas can positively influence the maturation of visual evoked potentials in preterm infants when breast milk is not available. PMID:8949693

  17. Auditory evoked potential measurements in elasmobranchs

    NASA Astrophysics Data System (ADS)

    Casper, Brandon; Mann, David

    2005-04-01

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

  18. Somatosensory evoked potentials and blood lactate levels.

    PubMed

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

    2015-09-01

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

  19. Caloric vestibular stimulation modulates nociceptive evoked potentials.

    PubMed

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

    2015-12-01

    Vestibular stimulation has been reported to alleviate central pain. Clinical and physiological studies confirm pervasive interactions between vestibular signals and somatosensory circuits, including nociception. However, the neural mechanisms underlying vestibular-induced analgesia remain unclear, and previous clinical studies cannot rule out explanations based on alternative, non-specific effects such as distraction or placebo. To investigate how vestibular inputs influence nociception, we combined caloric vestibular stimulation (CVS) with psychophysical and electrocortical responses elicited by nociceptive-specific laser stimulation in humans (laser-evoked potentials, LEPs). Cold water CVS applied to the left ear resulted in significantly lower subjective pain intensity for experimental laser pain to the left hand immediately after CVS, relative both to before CVS and to 1 h after CVS. This transient reduction in pain perception was associated with reduced amplitude of all LEP components, including the early N1 wave reflecting the first arrival of nociceptive input to primary somatosensory cortex. We conclude that cold left ear CVS elicits a modulation of both nociceptive processing and pain perception. The analgesic effect induced by CVS could be mediated either by subcortical gating of the ascending nociceptive input, or by direct modulation of the primary somatosensory cortex. PMID:26282602

  20. Auditory evoked potentials in panic disorder.

    PubMed Central

    Knott, V; Lapierre, Y D; Fraser, G; Johnson, N

    1991-01-01

    Neuroimaging studies of behavioral-induced anxiety in non-patients and of lactate-induced anxiety in panic disorder patients have indicated that normal and pathological anxiety may share a common pathway involving the temporal poles. As panic-related anxiety may reflect faulty temporopolar evaluative processing of input, the objective of this study was to examine sensory reactivity in panic disorder patients via scalp recordings of the late auditory evoked 'vertex' potential (LAEP) which appears to have a predominantly temporal lobe origin. Twelve patients diagnosed according to DSM-III criteria as panic disorder and ten normal controls served as subjects in this study. EEG was recorded from 16 scalp sites using a monopolar fronto-occipital derivation and LAEPs were separately averaged in response to four acoustic intensities. Analysis focused on group and electrode-site differences in the negative (N1) and positive (P2) component amplitudes of the LAEPs. Panic disorder patients were found to exhibit significantly larger N1 amplitudes across all stimulus intensities and across all recording sites. No significant group differences were observed with P2. Although the results provide indirect support for a temporal focus, other modulating influences must be considered in data interpretation. Images Fig. 3 Fig. 4 Fig. 5 PMID:1786264

  1. Cadmium induced alterations in somatosensory evoked potentials.

    PubMed

    Agar, A; Yargicoglu, P; Izgut, N; Senturk, U K; Oguz, Y

    1996-01-01

    Pregnant Swiss albino rats were divided into three groups: control (C), cadmium (Cd) and non-cadmium (NCd) groups. Control animals received tap water; the Cd rats received Cd as CdCl2 in their drinking water during the experimental period, while the NCd group was given Cd during pregnancy, and given tap water after birth. Twenty-two days after birth, 15 rats (for each group) were taken from their mothers and continued to be treated with Cd (Cd group) or tap water (C and NCd groups) for an additional 38 days. After the treatment period, somatosensory evoked potentials (SEPs) of the three groups were recorded from central (Cz) referenced to frontal (Fz) following left posterior tibial nerve (PTN) stimulation. Amplitude spectra of SEPs were computed by fast Fourier transform (FFT) algorithm. There was a significant amplitude decrease in 1-3.5 Hz in the NCd group and 1-3.5 and 14-20 Hz frequency bands of the Cd group compared with the control group. PMID:8876432

  2. Clinical aspects of the visually evoked potential.

    PubMed Central

    Weinstein, G W

    1977-01-01

    The visually evoked potential (VEP) was studied in normal and abnormal human subjects, and in Rhesus monkeys with central, paracentral, and peripheral photocoagulation lesions. A relatively simple protocol for clinical VEP testing is described. The monkeys showed similar VEP responses but these were smaller in amplitude than those obtained from human subjects. Central, but not paracentral or peripheral retinal lesions were associated with VEP abnormalities. For both monkey and human subjects, some variability of responses between normal and subjects was noted. Generally, there are differences in VEP responses obtained from the affected eye of abnormal subjects who had one eye which could serve as a control, as compared to responses from the normal eye. In these subjects as well as in subjects with two abnormal eyes, computer analysis of digitized VEP data from 10 Hz stimulus responses was performed. Fourier transformation analyses showed abnormalities which could be detected easily by evaluating the pattern of the amplitudes of the fundamental and first three harmonics. With this technique, it was possible to group correctly normal VEP's with eyes with normal visual acuity (greater than or equal to 20/30 or 0.67), and abnormal VEP's with eyes with poor visual acuity (less than 20/30 or 0.67) in 72% of cases. Analysis of the data obtained with 1 Hz and 10 Hz stimulation suggests that the components of the VEP related to visual acuity occur within the first 60-100 msec of the response, corresponding to the primary evoked response of Chiganek. The second, smaller wave of the response complex to 10 Hz flash stimuli corresponds to the primary evoked response, and is closely related to visual acuity. This was further supported in another series in which the digitized data was filtered around the stimulating frequency. It was possible to recognize visually this VEP waveform and subjectively interpret the record correctly in 85% of eyes with regard to visual acuity. Therefore, the clinician can "read" the VEP record in response to nonpatterned flash stimuli. This test was further validated in a series of patients with opacities of the ocular media, such as cataract, corneal scarring, and vitreous hemorrhage. VEP promises to become a procedure of diagnostic and prognostic value in ophthalmology. Images FIGURE 5 A FIGURE 5 B FIGURE 5 C FIGURE 7 A FIGURE 7 B FIGURE 7 C FIGURE 11 A FIGURE 11 B FIGURE 14 A FIGURE 14 B FIGURE 2 FIGURE 6 A FIGURE 6 B FIGURE 6 C FIGURE 6 D FIGURE 6 E FIGURE 6 F FIGURE 8 A FIGURE 8 B FIGURE 8 C FIGURE 8 D FIGURE 9 A FIGURE 9 B FIGURE 9 C FIGURE 9 D FIGURE 9 E FIGURE 12 A FIGURE 12 B FIGURE 12 C PMID:613533

  3. Brain Evoked Potentials and Intelligence: The Hendrickson Paradigm.

    ERIC Educational Resources Information Center

    Barrett, P. T.; Eysenck, H. J.

    1992-01-01

    An attempt to replicate the results with averaged evoked potentials (AEPs) of D. E. Hendrickson and A. E Hendrickson (1982) with 40 adults confirms a negative correlation between AEP variability and IQ. The Hendrickson paradigm is seen as no more than a well-controlled auditory evoked potential. (SLD)

  4. [Determination of irreversibility of clinical brain death : Electroencephalography and evoked potentials].

    PubMed

    Buchner, H; Ferbert, A

    2016-02-01

    Principally, in the fourth update of the rules for the procedure to finally determine the irreversible cessation of function of the cerebrum, the cerebellum and the brainstem, the importance of an electroencephalogram (EEG), somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) are confirmed. This paper presents the reliability and validity of the electrophysiological diagnosis, discusses the amendments in the fourth version of the guidelines and introduces the practical application, problems and sources of error.An EEG is the best established supplementary diagnostic method for determining the irreversibility of clinical brain death syndrome. It should be noted that residual brain activity can often persist for many hours after the onset of brain death syndrome, particularly in patients with primary brainstem lesions. The derivation and analysis of an EEG requires a high level of expertise to be able to safely distinguish artefacts from primary brain activity. The registration of EEGs to demonstrate the irreversibility of clinical brain death syndrome is extremely time consuming.The BAEPs can only be used to confirm the irreversibility of brain death syndrome in serial examinations or in the rare cases of a sustained wave I or sustained waves I and II. Very often, an investigation cannot be reliably performed because of existing sound conduction disturbances or failure of all potentials even before the onset of clinical brain death syndrome. This explains why BAEPs are only used in exceptional cases.The SEPs of the median nerve can be very reliably derived, are technically simple and with few sources of error. A serial investigation is not required and the time needed for examination is short. For these reasons SEPs are given preference over EEGs and BAEPs for establishing the irreversibility of clinical brain death syndrome. PMID:26785843

  5. Specialization of the auditory processing in harbor porpoise, characterized by brain-stem potentials

    NASA Astrophysics Data System (ADS)

    Bibikov, Nikolay G.

    2002-05-01

    Brain-stem auditory evoked potentials (BAEPs) were recorded from the head surface of the three awaked harbor porpoises (Phocoena phocoena). Silver disk placed on the skin surface above the vertex bone was used as an active electrode. The experiments were performed at the Karadag biological station (the Crimea peninsula). Clicks and tone bursts were used as stimuli. The temporal and frequency selectivity of the auditory system was estimated using the methods of simultaneous and forward masking. An evident minimum of the BAEPs thresholds was observed in the range of 125-135 kHz, where the main spectral component of species-specific echolocation signal is located. In this frequency range the tonal forward masking demonstrated a strong frequency selectivity. Off-response to such tone bursts was a typical observation. An evident BAEP could be recorded up to the frequencies 190-200 kHz, however, outside the acoustical fovea the frequency selectivity was rather poor. Temporal resolution was estimated by measuring BAER recovery functions for double clicks, double tone bursts, and double noise bursts. The half-time of BAERs recovery was in the range of 0.1-0.2 ms. The data indicate that the porpoise auditory system is strongly adapted to detect ultrasonic closely spaced sounds like species-specific locating signals and echoes.

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

    PubMed Central

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

    2014-01-01

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

  7. Visual evoked potentials in infants and children.

    PubMed

    Taylor, M J; McCulloch, D L

    1992-07-01

    Visual evoked potential (VEP) studies are of great value in a wide variety of pediatric patients, including those with disorders of the sensory visual pathway and those at risk for visual pathway damage. VEPs are simple, non-invasive, and are particularly appropriate for infants and young children who cannot communicate visual symptoms or cooperate for standard vision assessment. VEPs in pediatric patients have the following main purposes: (1) detecting lesions causing dysfunction of the sensory visual pathways (the VEP is a sensitive indicator of subclinical lesions and can be used to differentiate visual impairment from visual inattention in young infants); (2) confirming functional loss when disorders of the visual system are present; (3) quantifying visual impairment in patients with known visual disorders, accomplished either empirically by noting the severity of the VEP abnormality to flash and pattern stimuli or by visual acuity estimation studies (early quantification of vision loss allows referral to early intervention programs, which can ameliorate the long-term consequences of the disability); (4) monitoring patients who are at risk for visual complications either from diseases (such as hydrocephalus or neurofibromatosis) or as a complication of therapeutic intervention (e.g., neurosurgery, chemotherapy) to help detect and avoid long-term sequelae of such therapies on the developing nervous system; (5) establishing prognosis for visual and systemic recovery based on flash VEPs for specific pediatric disorders including perinatal asphyxia in full-term neonates, acute-onset cortical blindness, and, to a fair extent, in comatose children; and (6) in some cases, contributing to the differential diagnosis. Abnormalities of flash and/or pattern VEPs are generally nonspecific to the type of exact location of the lesion, except in distinguishing prefrom postchiasmal lesions. However, in certain conditions, such as the hereditary ataxias of childhood, VEP abnormalities may help in the diagnosis. Similarly, deterioration in VEPs may help differentiate progressive from static encephalopathies. VEPs have become an indispensable tool in pediatric ophthalmology and neurology. They will probably play an increasingly important role in the future, primarily due to the difficulty in assessing visual system function in young or ill children and the VEP's sensitivity to subclinical damage in this aspect of the central nervous system. PMID:1517404

  8. 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...

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

    PubMed

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

    2016-05-15

    Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases. PMID:27084224

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

    PubMed

    Guérit, J M

    2000-12-01

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

  11. USE OF SENSORY EVOKED POTENTIALS IN NEUROTOXICITY TESTING OF WORKERS

    EPA Science Inventory

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

  12. 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...

  13. [Auditory evoked potentials in addicts to organic solvent inhalation].

    PubMed

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

    1996-01-01

    Organic solvents affect the membrane lipids of neurons and glial cell. This led us to search for auditory damage, by means of brainstem auditory evoked responses, in subjects with chronic inhalation of thinner. Waves III and V showed delayed latency at an intensity of 90 dB, and wave V was delayed at 70 and 30 dB; the interwave intervals I-III and I-V at 90 dB and the interpeak I-V at 70 dB were also retarded. Three subjects did not show a response to stimulation at 30 dB: pure tone audiometry showed biaural mild hypoacusia in them. These results show that chronic inhalation of thinner may alter the auditory pathway of addicts. PMID:9005514

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

    PubMed

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

    2016-02-01

    Previously, we reported a case of brainstem cavernous hemangioma showing false positive responses to electromyographic tracheal tube (EMG tube). We concluded that the cause was spontaneous respiration accompanied by vocal cord movement. We report a case of left vertebral artery aneurysm showing evoked potentials on bilateral electrodes by the left vagus nerve stimulation to EMG tube. An 82-year-old woman underwent clipping of a left unruptured vertebral artery-posterior inferior cerebellar artery aneurysm. General anesthesia was induced with remifentanil, propofol and suxamethonium, and was maintained with oxygen, air, remifentanil and propofol. We monitored somatosensory evoked potentials, motor evoked potentials, and electromyogram of the vocal cord. When the manipulation reached brainstem and the instrument touched the left vagus nerve, evoked potentials appeared on bilateral electrodes. EMG tube is equipped with two electrodes on both sides. We concluded that the left vagus nerve stimulation generated evoked potentials of the left laryngeal muscles, and they were simultaneously detected as potential difference between two electrodes on both sides. EMG tube is used to identify the vagus nerve. However, it is necessary to bear in mind that each vagus nerve stimulation inevitably generates evoked potentials on bilateral electrodes. PMID:27017772

  15. Chronic network stimulation enhances evoked action potentials

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

  18. Deblurring visual evoked potentials using commercially available software.

    PubMed

    Zarkowski, Paul A; Shin, Chul-Jin; Holmes, Mark D

    2006-04-01

    Visual evoked potentials are useful clinical tools to study visual pathways of the brain. Although the temporal resolution is unsurpassed by other brain imaging technologies, the spatial resolution is diminished or blurred by the low conductance of the electrical signals through the skull. Methods have been proposed to improve the spatial resolution by downwardly projecting the electrical signals measured on the scalp to the surface of the cerebral cortex through the inverse solution of the equations governing static current flow. We describe the adaptation and combination of commercially available engineering software programs to solve this inverse problem and report the results of a sample run of the system. Before deblurring, the visual evoked potentials appeared to be diffusely localized over the posterior scalp. After deblurring, the visual evoked potentials were only found at the electrodes closest to the visual cortex, as would be predicted by our current knowledge of neuroanatomy. PMID:16563552

  19. [Prediction by means of endogenous and exogenous evoked potentials of the favorable evolution of a prolonged coma].

    PubMed

    Michel, C; Denison, S; Minne, C; Guérit, J M

    1998-09-01

    A neurophysiological follow-up (EEG, exogenous and endogenous evoked potentials--EP) was performed over a 4-month period in a patient who presented a long-lasting coma following a cardiac arrest and an amniotic embolism. A pure anoxic aetiology was ruled out starting from the second day on the basis of a dissociation between mildly altered flash visual EP and markedly altered somatosensory EP, indicating focal brain-stem pathology. Endogenous EP reappeared after 12 days. This patient recovered consciousness after 51 days. Despite the absence of MRI abnormalities, we put forward the hypothesis that a brain-stem embolism had, in fact, worsened the clinical picture of an actually moderate anoxia. This case exemplifies the interest of an integrated neurophysiological approach (EEG, exogenous three-modality EP and endogenous EP) in the early evaluation of coma. It also illustrates the complement between structural imaging and functional assessment of the nervous system. PMID:9793066

  20. 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...

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

    PubMed

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

    2015-09-01

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

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

    PubMed

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

    1983-09-01

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

  3. On hemispheric differences in evoked potentials to speech stimuli

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

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

    PubMed

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

    2009-07-01

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

  5. 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 ...

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

    PubMed

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

    2013-02-01

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

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

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  8. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    ERIC Educational Resources Information Center

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

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

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

    PubMed

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

    2010-12-01

    Hyperventilation is often associated with stress, an established trigger factor for migraine. Between attacks, migraine is associated with a deficit in habituation to visual-evoked potentials (VEP) that worsens just before the attack. Hyperventilation slows electroencephalographic (EEG) activity and decreases the functional response in the occipital cortex during visual stimulation. The neural mechanisms underlying deficient-evoked potential habituation in migraineurs remain unclear. To find out whether hyperventilation alters VEP habituation, we recorded VEPs before and after experimentally induced hyperventilation lasting 3 min in 18 healthy subjects and 18 migraine patients between attacks. We measured VEP P100 amplitudes in six sequential blocks of 100 sweeps and habituation as the change in amplitude over the six blocks. In healthy subjects, hyperventilation decreased VEP amplitude in block 1 and abolished the normal VEP habituation. In migraine patients, hyperventilation further decreased the already low block 1 amplitude and worsened the interictal habituation deficit. Hyperventilation worsens the habituation deficit in migraineurs possibly by increasing dysrhythmia in the brainstem-thalamo-cortical network. PMID:20625915

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

    PubMed

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

    1996-09-01

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

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

    PubMed

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

    2015-12-01

    Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery. PMID:26493491

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

    PubMed Central

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

    1992-01-01

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

  13. Establishing an evoked-potential vision-tracking system

    NASA Technical Reports Server (NTRS)

    Skidmore, Trent A.

    1991-01-01

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

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

    PubMed

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

    2015-11-01

    Experience continuously imprints on the brain at allstages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show thatthe perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever amemory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics. PMID:26455302

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

    PubMed

    Paulus, W

    1988-01-01

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

  16. [The effect of chronic Vagus Nerve Stimulation (VNS) on the central conduction time assessed by multimodal evoked potentials in patients with drug resistant epilepsy: preliminary report].

    PubMed

    Rysz, Andrzej; Koszewski, Waldemar

    2003-01-01

    Changes over time in evoked potentials of various modality (VEP, SSEP and BAEP) were analyzed in 3 patients, submitted to chronic Vagus Nerve Stimulation (VNS) due to drug resistant epilepsy. The aim of a study was to establish which cerebral structures are most prone to change their baseline electrophysiological status in consequence of chronic VNS. Evoked potentials were examined before the Vagus Nerve Stimulator implantation and at arbitrarily defined follow-ups several months after the implantation. Preliminary results obtained in a small group of 3 patients suggest a possible prolongation of the central conduction time in the examined modalities of evoked potentials due to the VNS treatment. A hypothetical mechanism of antiepileptic VNS action might be related to the permanent stimulation of brainstem and cortical structures that limit seizures propagation through hyperpolarisation both at the cortical level and in subcortical structures. PMID:15174257

  17. Methods for quantifying intra- and inter-subject variability of evoked potential data applied to the multifocal visual evoked potential.

    PubMed

    Dandekar, Sangita; Ales, Justin; Carney, Thom; Klein, Stanley A

    2007-09-30

    Differences in cortical geometry within and between subjects can complicate multifocal visual evoked potential (mfVEP) and standard evoked potential (EP) intra- and inter-subject comparisons. We present methods for aligning temporal intra- and inter-subject data prior to comparison. Multiple groups have informally observed that the two dominant temporal principal components (PCs) of the pattern reversal visual evoked potential (VEP) obtained with singular value decomposition (SVD) exhibit little inter-subject variability relative to the inter-subject variability of the raw VEP. We present methods that employ the temporal PCs to formally quantify intra- and inter-subject variability of the mfVEP. When SVD was applied to data from eight subjects separately, it was found that two PCs accounted for, on average, 73% of intra-subject variance. When a single SVD was applied to combined data from multiple subjects, it was found that two PCs accounted for 67% of inter-subject variance. We used the 2D temporal subspaces derived from SVD as a basis for intra- and inter-subject comparisons. PMID:17673298

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

    PubMed

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

    2010-12-01

    Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. To address this hypothesis, we explored in a group of healthy participants the combined effects of cue-induced expectancy and baroreceptor activity on the amplitude of pain-evoked ERPs. Brief nociceptive skin stimuli were delivered during a simple visual task; half were preceded by a visual forewarning cue, and half were unpredictable. Nociceptive stimuli were timed to coincide either with systole (maximum activation of cardiac baroreceptors) or with diastole (minimum baroreceptor activation). We observed a strong interaction between expectancy and cardiac timing for the amplitude of the P2 ERP component; no effects were observed for the N2 component. Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive-affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain. PMID:20965656

  19. Are ipsilateral motor evoked potentials subject to intracortical inhibition?

    PubMed

    McCambridge, Alana B; Stinear, James W; Byblow, Winston D

    2016-03-01

    Paired-pulse transcranial magnetic stimulation (TMS) can be used to examine intracortical inhibition in primary motor cortex (M1), termed short-interval intracortical inhibition (SICI). To our knowledge, SICI has only been demonstrated in contralateral motor evoked potentials (MEPs). Ipsilateral MEPs (iMEPs) are assumed to reflect excitability of an uncrossed oligosynaptic pathway, and can sometimes be evoked in proximal upper-limb muscles using high-intensity TMS. We examined whether iMEPs in the biceps brachii (BB) would be suppressed by subthreshold conditioning, therefore demonstrating SICI of iMEPs. TMS was delivered to the dominant M1 to evoke conditioned (C) and nonconditioned (NC) iMEPs in the nondominant BB of healthy participants during weak bilateral elbow flexion. The conditioning stimulus intensities tested were 85%, 100%, and 115% of active motor threshold (AMT), at 2 ms and 4 ms interstimulus intervals (ISI). The iMEP ratio (C/NC) was calculated for each condition to assess the amount of inhibition. Inhibition of iMEPs was present at 2 ms ISI with 100% and 115% AMT (bothP< 0.03), mediated by a reduction in persistence and size (allP< 0.05). To our knowledge, this is the first demonstration of SICI of iMEPs. This technique may be useful as a tool to better understand the role of ipsilateral M1 during functional motor tasks. PMID:26792890

  20. [Auditory brain stem evoked potentials of average latency in dyslexics and controls].

    PubMed

    Poblano, A; Druet, N; Peñaloza, Y; Jiménez, R

    1991-06-01

    The goal of this paper was to study the auditory pathway of nine controls and nine pure dyslexic subjects using brainstem auditory evoked responses and middle latency responses. We found no differences in latency and amplitude between both groups; only a small difference in the V right/V left relation in favour of the right V wave in controls and left V wave in dyslexics. This findings is discussed in relation to cerebral dominance. PMID:1910559

  1. Conditioning effect of transcranial magnetic stimulation evoking motor?evoked potential on V?wave response

    PubMed Central

    Grosprtre, Sidney; Martin, Alain

    2014-01-01

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

  2. Short latency vestibular evoked potentials in the chicken embryo

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  3. [New methods of stimulation of evoked visual potentials].

    PubMed

    Sóth, J; Schingler, F

    1995-04-01

    We report new approach to stimulation of visual evoked potentials generating graphical shemes on display of personal computer. System is based on original research of authors. It permits a stimulation of individual types of retinal cells using either pattern reversal modus or movements, or their mutual combination. System is suitable for introduction into common clinical praxis due to availability and simplicity. It allow standard routine examination of not only usual pattern reversal stimulation but also of movement stimulation. Until now, standardly managed devises do not permit examine later way of stimulation. PMID:8591612

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  5. Cortical processing of musical consonance: an evoked potential study.

    PubMed

    Itoh, Kosuke; Suwazono, Shugo; Nakada, Tsutomu

    2003-12-19

    Cortical processes underlying perception of musical consonance were investigated by long-latency auditory evoked potentials (EPs). Subjects listened to a random sequence of dyadic pure tones paired at various pitch intervals (1, 4, 6, 7, or 9 semitones). Amplitudes of P2 and N2 components of auditory EPs were significantly modulated by pitch interval of the dyads, being most negative for 1 semitone (minor second) and least negative or most positive for 7 semitones (perfect fifth). The results indicate that neural processing of consonance depend not only on peripheral mechanisms in the inner ear but also on higher associative processing of pitch relationships in the cerebral cortex. PMID:14663180

  6. Pattern-visual evoked potentials in thinner abusers.

    PubMed

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

    1996-01-01

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

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

    PubMed

    Murofushi, Toshihisa

    2016-08-01

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

  8. Continuous time wavelet entropy of auditory evoked potentials.

    PubMed

    Cek, M Emre; Ozgoren, Murat; Savaci, F Acar

    2010-01-01

    In this paper, the continuous time wavelet entropy (CTWE) of auditory evoked potentials (AEP) has been characterized by evaluating the relative wavelet energies (RWE) in specified EEG frequency bands. Thus, the rapid variations of CTWE due to the auditory stimulation could be detected in post-stimulus time interval. This approach removes the probability of missing the information hidden in short time intervals. The discrete time and continuous time wavelet based wavelet entropy variations were compared on non-target and target AEP data. It was observed that CTWE can also be an alternative method to analyze entropy as a function of time. PMID:20022318

  9. 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 ...

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

    PubMed

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

    2012-07-01

    Electrically evoked compound action potentials (ECAPs) are widely used to study the excitability of the auditory nerve and stimulation properties in cochlear implant (CI) users. However, ECAP detection can be difficult and very subjective at near-threshold stimulation levels or in spread of excitation measurements. In this study, we evaluated the statistical properties of the background noise (BN) and the postaverage residual noise (RN) in ECAP measurements in order to determine an objective detection criterion. For the estimation of the BN and the RN, a method currently used in auditory brainstem response measurements was applied. The potential benefit of using weighted (Bayesian) averages was also examined. All estimations were performed with a set of approximately 360 ECAP measurements recorded from five human CI users of the CII or HiRes90K device (advanced bionics). Results demonstrated that the BN was normally distributed and the RN decreased according to the square root of the number of averages. No additional benefit was observed by using weighted averaging. The noise was not significantly different either at different stimulation intensities or across recording electrodes along the cochlea. The analysis of the statistical properties of the noise indicated that a signal-to-noise ratio of 1.7 dB as a detection criterion corresponds to a false positive detection rate of 1% with the used measurement setup. PMID:22510942

  11. A novel shape analysis technique for somatosensory evoked potentials.

    PubMed

    Agrawal, Gracee; Sherman, David; Thakor, Nitish; All, Angelo

    2008-01-01

    Somatosensory evoked potentials (SEP) have been shown to be an important electrophysiological measure to assess the integrity of the spinal cord. However the peaks in the SEP waveform are often undetectable due to low signal-to-noise (SNR) ratio. Sometimes they also become indistinct during injury when the SEP flattens. Hence time-domain analysis methods are often subject to errors, and need human-expert intervention. In this paper, we propose a new technique for analyzing the shape of the evoked potentials, in which slope information is obtained for the entire signal in specific time bins. Apart from solving the problems associated with present methods, this technique has an added advantage of analyzing the SEP signal as a whole rather than simply a few peaks. The efficacy of this technique was investigated on SEP signals recorded from 12 rats before and after contusion spinal cord injury at thoracic vertebra T8. The statistical analysis results revealed significant effect of injury to hindlimbs, whereas almost none to forelimbs. Thus, the results show high potential of this technique to differentiate between normal and injured spinal cord. PMID:19163762

  12. Parametric modeling of somatosensory evoked potentials using discrete cosine transform.

    PubMed

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

    2001-11-01

    This paper introduces a parametric method for identifying the somatosensory evoked potentials (SEPs). The identification was carried out by using pole-zero modeling of the SEPs in the discrete cosine transform (DCT) domain. It was found that the DCT coefficients of a monophasic signal can be sufficiently approximated by a second-order transfer function with a conjugate pole pair. The averaged SEP signal was modeled by the sum of several second-order transfer functions with appropriate zeros and poles estimated using the least square method in the DCT domain. Results of the estimation demonstrated that the model output was in an excellent agreement with the raw SEPs both qualitatively and quantitatively. Comparing with the common autoregressive model with exogenous input modeling in the time domain, the DCT domain modeling achieves a high goodness of fitting with a very low model order. Applications of the proposed method are possible in clinical practice for feature extraction, noise cancellation and individual component decomposition of the SEPs as well as other evoked potentials. PMID:11686634

  13. Vestibular evoked myogenic potentials in patients with rheumatoid arthritis

    PubMed Central

    Heydari, Nahid; Hajiabolhassani, Fahimeh; Fatahi, Jamileh; Movaseghi, Shafieh; Jalaie, Shohreh

    2015-01-01

    Background: Rheumatoid arthritis (RA) is an autoimmune systemic disease. Most common autoimmune diseases are multisystem disorders that may also present with otological manifestations, and autoimmune inner ear disease accompanied by vestibular dysfunction. This study aimed to compare the vestibular function between RA patients and normal subjects using cervical vestibular evoked myogenic potentials (cVEMPs). Methods: In this cross- sectional study, 25patients with RA (19 female and 6 male: mean (±SD) age, 40.00 (±7.92) years) and 20 healthy subjects (15 female and 5 male: mean (±SD) age, 35.35 (±10.48) years) underwent cVEMPs, using 500 Hz-tone bursts at 95 dB nHL intensity level. Data were analyzed using independent sample t-test through SPSS software v. 16. Results: The mean peak latency of p13 was significantly higher in RA patients (p<0.001). The mean peak latency of n23 was significantly higher in patients in the left ear (p=0.03). Vestibular evoked myogenic potential (VEMP) responses were present in all (100%) of the participants. There were no significant differences in mean peak to peak amplitude and amplitude ratio between the two groups. Conclusion: According to the prolonged latency of VEMP responses in RA patients, lesions in the retrolabyrinthine, especially in the vestibulospinal tract are suspected. PMID:26478874

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

    PubMed

    Gourevitch, B; Le Bouquin-Jeannes, R

    2003-07-01

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

  15. A New Measure for Monitoring Intraoperative Somatosensory Evoked Potentials

    PubMed Central

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

    2014-01-01

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

  16. Using Evoked Potentials to Match Interaural Electrode Pairs with Bilateral Cochlear Implants

    PubMed Central

    Delgutte, Bertrand

    2007-01-01

    Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by providing binaural cues normally important for accurate sound localization and speech reception in noise. Psychophysical observations suggest that a key issue for the implementation of a successful binaural prosthesis is the ability to match the cochlear positions of stimulation channels in each ear. We used a cat model of bilateral cochlear implants with eight-electrode arrays implanted in each cochlea to develop and test a noninvasive method based on evoked potentials for matching interaural electrodes. The arrays allowed the cochlear location of stimulation to be independently varied in each ear. The binaural interaction component (BIC) of the electrically evoked auditory brainstem response (EABR) was used as an assay of binaural processing. BIC amplitude peaked for interaural electrode pairs at the same relative cochlear position and dropped with increasing cochlear separation in either direction. To test the hypothesis that BIC amplitude peaks when electrodes from the two sides activate maximally overlapping neural populations, we measured multiunit neural activity along the tonotopic gradient of the inferior colliculus (IC) with 16-channel recording probes and determined the spatial pattern of IC activation for each stimulating electrode. We found that the interaural electrode pairings that produced the best aligned IC activation patterns were also those that yielded maximum BIC amplitude. These results suggest that EABR measurements may provide a method for assigning frequency–channel mappings in bilateral implant recipients, such as pediatric patients, for which psychophysical measures of pitch ranking or binaural fusion are unavailable. PMID:17225976

  17. Automatic denoising of single-trial evoked potentials.

    PubMed

    Ahmadi, Maryam; Quian Quiroga, Rodrigo

    2013-02-01

    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

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

    EPA Science Inventory

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

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

    " The pattern evok...

  19. Visual evoked potentials and selective attention to points in space

    NASA Technical Reports Server (NTRS)

    Van Voorhis, S.; Hillyard, S. A.

    1977-01-01

    Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

  20. Visual Evoked Potential: Computer Assisted Acquisition and Processing

    PubMed Central

    Browder, M. W.; Blaine, G. J.; Montrose, J. K.; Coben, L. A.; Thomas, L. J.

    1980-01-01

    A system to simplify the collection and processing of averaged visual evoked potentials (AVEPs) has been developed. The overall system can be described as a “loosely-coupled” distributed processing system. The coupling between components of the system is in the form of data transfer via machine-readable magnetic storage media, i.e. flexible diskette and industry-compatible 9-track magnetic tape. A microprocessor-based system was developed to provide flexible parameterization of clinical protocols and the collection of AVEPs. Feature-detection algorithms were developed on a minicomputer system to simplify and improve the accuracy of previously used manual scoring methods. An editing system was also developed to allow operator verification and editing of the features located by the automatic system. The parameters of interest are then included in a statistical database on a large computer for further analysis.

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

    PubMed

    Tandon, O P

    1990-07-01

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

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

    PubMed Central

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

    2015-01-01

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

  3. Conscious Wireless Electroretinogram and Visual Evoked Potentials in Rats

    PubMed Central

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

    2013-01-01

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

  4. 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...

  5. Brainstem Auditory Evoked Potentials (BAEP)- A Pilot Study Conducted on Young Healthy Adults from Central India

    PubMed Central

    Gandhe, Mahendra Bhauraoji; Gandhe, Swapnali Mahendra; Puttewar, A.N.; Saraf, Chhaya; Singh, Ramji

    2014-01-01

    Objective: To Evaluate I, II, III, IV, V wave latencies and I-III, III-V, I-V inter-peak latencies and V/I wave amplitude ratio in Normal subjects in Central India. Methods: We recorded BAEP from 50 healthy normal subjects from the community of same sex and geographical setup. The absolute, interpeak and wave V/I amplitude ratio were measurement and recording was done using RMS EMG EP MARK II machine manufactured by RMS recorders and Medicare system, Chandigarh. Result: Absolute, interpeak and wave V/I amplitude ratio were measured in normal subjects and compared with other previous studies. Conclusion: This study was conducted as exploratory pilot study only on male healthy controls. Since, the study conducted in different regions, there are some differences in the latencies and interpeak latencies and amplitude ratio but they are within range, so reference range of this study can be used for future studies in this Wardha region of Central India. PMID:25120971

  6. High stimulus rate brainstem auditory evoked potential in benign paroxysmal positional vertigo.

    PubMed

    He, Juan-Wen; Gong, Qiang; Wang, Xue-Feng; Xiao, Zheng

    2015-09-01

    The objective of this study is to use high (49/s) and low (9/s) stimulation rates of the BAEP to investigate the possible mechanism responsible for BPPV. A total of 81 patients (55 women and 26 men, mean age ± SD = 54.6 ± 15.0) with idiopathic BPPV, as well as 106 control subjects (70 women and 36 men, mean age ± SD = 51.2 ± 16.3) participated in the study. The results of high (49/s) and low (9/s) stimulation rates of the BAEP test were compared and analyzed. The difference in BAEP wave I peak latencies between low and high stimulation rate (DPL I) and BAEP wave I peak latency in high stimulation (HPL I) of affected ears (0.24 ± 0.14 and 1.91 ± 0.21 ms) in BPPV patients were significantly prolonged when compared with the controls (0.10 ± 0.08 and 1.76 ± 0.18 ms) and unaffected ears (0.12 ± 0.10 and 1.82 ± 0.21 ms) (p < 0.001). The abnormal rate of DPL I in the affected ear (52/83, 62.65 %) was significantly higher than that in the unaffected ear (7/79, 8.86 %) and the normal left ear (4/106, 3.77 %). We suggest that ischemia of the inner ear might be one of the causes of BPPV and that DPL I may be used to assess the ischemic degree in subjects over 20 years old. PMID:25005432

  7. Contact heat evoked potentials using simultaneous EEG and fMRI and their correlation with evoked pain

    PubMed Central

    Roberts, Katherine; Papadaki, Anastasia; Gonçalves, Carla; Tighe, Mary; Atherton, Duncan; Shenoy, Ravikiran; McRobbie, Donald; Anand, Praveen

    2008-01-01

    Background The Contact Heat Evoked Potential Stimulator (CHEPS) utilises rapidly delivered heat pulses with adjustable peak temperatures to stimulate the differential warm/heat thresholds of receptors expressed by Aδ and C fibres. The resulting evoked potentials can be recorded and measured, providing a useful clinical tool for the study of thermal and nociceptive pathways. Concurrent recording of contact heat evoked potentials using electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) has not previously been reported with CHEPS. Developing simultaneous EEG and fMRI with CHEPS is highly desirable, as it provides an opportunity to exploit the high temporal resolution of EEG and the high spatial resolution of fMRI to study the reaction of the human brain to thermal and nociceptive stimuli. Methods In this study we have recorded evoked potentials stimulated by 51°C contact heat pulses from CHEPS using EEG, under normal conditions (baseline), and during continuous and simultaneous acquisition of fMRI images in ten healthy volunteers, during two sessions. The pain evoked by CHEPS was recorded on a Visual Analogue Scale (VAS). Results Analysis of EEG data revealed that the latencies and amplitudes of evoked potentials recorded during continuous fMRI did not differ significantly from baseline recordings. fMRI results were consistent with previous thermal pain studies, and showed Blood Oxygen Level Dependent (BOLD) changes in the insula, post-central gyrus, supplementary motor area (SMA), middle cingulate cortex and pre-central gyrus. There was a significant positive correlation between the evoked potential amplitude (EEG) and the psychophysical perception of pain on the VAS. Conclusion The results of this study demonstrate the feasibility of recording contact heat evoked potentials with EEG during continuous and simultaneous fMRI. The combined use of the two methods can lead to identification of distinct patterns of brain activity indicative of pain and pro-nociceptive sensitisation in healthy subjects and chronic pain patients. Further studies are required for the technique to progress as a useful tool in clinical trials of novel analgesics. PMID:19091117

  8. Pattern visual evoked potential (PVEP) evaluation in hypothyroidism.

    PubMed

    Nazliel, B; Akbay, E; Irkeç, C; Yetkin, I; Ersoy, R; Törüner, F

    2002-12-01

    Dysfunction of the central nervous system (CNS) is an important consequence of thyroid hormone deficiency. Evoked potentials like visual evoked potentials (VEP) provide a reliable and objective measure of function in related sensory system and tracts. In this study pattern-shift VEP (PVEP) recordings were performed on 48 newly diagnosed hypothyroid patients. Twenty-four had sub-clinical and 24 had overt hypothyroidism. None of the patients had clinical symptoms or signs referable to CNS dysfunction. Their mean age was 44+/-12 yr. The response to pattern stimulation on the normal control subjects was a triphasic response with a prominent positive wave (P100) with a peak latency of 84-105 (mean: 96+/-4) milliseconds (ms). In patients with hypothyroidism mean P100 latency was (mean: 97+/-6) ms and the difference between the 2 groups was not statistically significant. (p>0.05) Delays above the average latency +/-2.5 SD of the mean of the control subjects was defined as a criteria for an abnormality. According to defined criteria 6 (12.5%) patients demonstrated abnormal PVEP at least on one tested side. Previous studies conducted on small patient populations stated there is high percentage of VEP abnormalities in hypothyroid patients. However, this fact was not confirmed by our study. We believe abnormalities of PVEP will be more prominent in untreated patients in the advanced stage of the disease, or in patients who have a neurological involvement; such as apathy, impaired memory or cerebellar dysfunction. Consecutive studies, in a more clearly defined and selected patient population, are needed to confirm and settle this issue. PMID:12553554

  9. The effect of different hypertension models on visual evoked potentials.

    PubMed

    Hacioglu, Gulay; Agar, Aysel; Ozkaya, Gul; Yargicoglu, Piraye; Gumuslu, Saadet

    2002-11-01

    Even though there is an abundance of information about the complications of hypertension, studies of its influence on visual evoked potentials (VEPs) are rare. In previous studies, it was pointed out that hypertension induces changes on VEPs. However, it has not yet been clarified which models of hypertension are more effective on VEPs. The aim of this study was to investigate this subject in rats. Animals were divided equally into six groups: control group (C), sham operated (Sham), two kidney-one clip (2K-1C), one kidney-one clip (1K-1C), deoxycorticosterone-salt (DOCA), and N-omega-nitro-L-arginine-methyl ester (L-NAME) groups. Mean arterial pressure was significantly higher in four hypertensive groups compared with control and sham groups, but there were no significant differences either among hypertensive groups or between sham and control groups. At the end of the experimental period, flash visual evoked potentials were recorded. The mean latencies of P1, N1, P2, N2, and P3 components were significantly prolonged in all hypertensive groups compared with the control and sham groups. The mean latencies of all VEPs components in the L-NAME group were longer than in the other hypertensive groups. Thiobarbituric acid-reactive substances (TBARS) were determined as an indicator of lipid peroxidation. Our data showed that hypertension caused a significant increase of lipid peroxidation in brain and retinal tissues. Additionally, plasma renin activity (PRA) was highest in the 2K-1C group and lowest in the DOCA group. PMID:12625192

  10. Laser-Evoked Vertex Potentials Predict Defensive Motor Actions

    PubMed Central

    Moayedi, M.; Liang, M.; Sim, A. L.; Hu, L.; Haggard, P.; Iannetti, G. D.

    2015-01-01

    The vertex potential is the largest response that can be recorded in the electroencephalogram of an awake, healthy human. It is elicited by sudden and intense stimuli, and is composed by a negative–positive deflection. The stimulus properties that determine the vertex potential amplitude have been well characterized. Nonetheless, its functional significance remains elusive. The dominant interpretation is that it reflects neural activities related to the detection of salient stimuli. However, given that threatening stimuli elicit both vertex potentials and defensive movements, we hypothesized that the vertex potential is related to the execution of defensive actions. Here, we directly compared the salience and motoric interpretations by investigating the relationship between the amplitude of laser-evoked potentials (LEPs) and the response time of movements with different defensive values. First, we show that a larger LEP negative wave (N2 wave) predicts faster motor response times. Second, this prediction is significantly stronger when the motor response is defensive in nature. Third, the relation between the N2 wave and motor response time depends not only on the kinematic form of the movement, but also on whether that kinematic form serves as a functional defense of the body. Therefore, the N2 wave of the LEP encodes key defensive reactions to threats. PMID:26250779

  11. Laser-Evoked Vertex Potentials Predict Defensive Motor Actions.

    PubMed

    Moayedi, M; Liang, M; Sim, A L; Hu, L; Haggard, P; Iannetti, G D

    2015-12-01

    The vertex potential is the largest response that can be recorded in the electroencephalogram of an awake, healthy human. It is elicited by sudden and intense stimuli, and is composed by a negative-positive deflection. The stimulus properties that determine the vertex potential amplitude have been well characterized. Nonetheless, its functional significance remains elusive. The dominant interpretation is that it reflects neural activities related to the detection of salient stimuli. However, given that threatening stimuli elicit both vertex potentials and defensive movements, we hypothesized that the vertex potential is related to the execution of defensive actions. Here, we directly compared the salience and motoric interpretations by investigating the relationship between the amplitude of laser-evoked potentials (LEPs) and the response time of movements with different defensive values. First, we show that a larger LEP negative wave (N2 wave) predicts faster motor response times. Second, this prediction is significantly stronger when the motor response is defensive in nature. Third, the relation between the N2 wave and motor response time depends not only on the kinematic form of the movement, but also on whether that kinematic form serves as a functional defense of the body. Therefore, the N2 wave of the LEP encodes key defensive reactions to threats. PMID:26250779

  12. [Primary extinct evoked cerebral potentials in the diagnosis of brain death].

    PubMed

    Haupt, W F

    1991-09-01

    In a collective of 82 patients with the clinical signs of brain death and examination of evoked cerebral potentials the incidence of primary abolished evoked potentials was studied. The initial examination occurred at the same time after onset of disease in both groups. We found a marked correlation with the clinical course of the patients. Whereas the group with primary loss of evoked potentials mainly contained patients with intracerebral and subarachnoid hemorrhages and short survival times, the other group with primary preserved evoked potentials showed a high rate of ischemic infarctions and longer survival periods. The rate of primary abolished evoked potentials can be lowered only by routine examination at the earliest time possible. Outside of neurological intensive care units the early examination of evoked potentials is hardly possible. In these units, the EEG remains the technical examination of choice in the confirmation of brain death. PMID:1765027

  13. BAER - brainstem auditory evoked response

    MedlinePlus

    ... a reclining chair or bed and remain still. Electrodes are placed on your scalp and on each ... earphones you are wearing during the test. The electrodes pick up the brain's responses to these sounds ...

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

    PubMed

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

    2014-10-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  17. Visual evoked potentials in children prenatally exposed to methylmercury.

    PubMed

    Yorifuji, Takashi; Murata, Katsuyuki; Bjerve, Kristian S; Choi, Anna L; Weihe, Pal; Grandjean, Philippe

    2013-07-01

    Prenatal exposure to methylmercury can cause both neurobehavioral deficits and neurophysiological changes. However, evidence of neurotoxic effects within the visual nervous system is inconsistent, possibly due to incomplete statistical adjustment for beneficial nutritional factors. We evaluated the effect of prenatal methylmercury exposure on visual evoked potential (VEP) latencies in Faroese children with elevated prenatal methylmercury exposure. A cohort of 182 singleton term births was assembled in the Faroe Islands during 1994-1995. At age 7 years, VEP tracings were obtained from 139 cohort subjects after exclusion of subjects with abnormal vision conditions. We used multiple regression analysis to evaluate the association of mercury concentrations in cord blood and maternal hair at parturition with VEP latencies after adjustment for potential confounders that included the cord-serum phospholipid concentration of n-3 polyunsaturated fatty acids (PUFAs) and the duration of breastfeeding. Unadjusted correlations between mercury exposure and VEP latencies were equivocal. Multiple regression models showed that increased mercury concentrations, especially in maternal hair, were associated with delayed latencies for VEP peak N145. After covariate adjustment, a delay of 2.22 ms (p=0.02) was seen for each doubling of the mercury concentration in maternal hair. In agreement with neuropsychological findings, the present study suggests that prenatal methylmercury exposure may have an adverse effect on VEP findings despite the absence of clinical toxicity to the visual system. However, this association was apparent only after adjustment for n-3 PUFA status. PMID:23548974

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

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

    1991-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Snyder, E.; Hillyard, S. A.

    1976-01-01

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

  1. Vestibular evoked myogenic potentials in patients with BPPV

    PubMed Central

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

    2011-01-01

    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

  2. Cortical processing of human gut sensation: an evoked potential study.

    PubMed

    Hobday, David I; Hobson, Anthony R; Sarkar, Sanchoy; Furlong, Paul L; Thompson, David G; Aziz, Qasim

    2002-08-01

    The rectum has a unique physiological role as a sensory organ and differs in its afferent innervation from other gut organs that do not normally mediate conscious sensation. We compared the central processing of human esophageal, duodenal, and rectal sensation using cortical evoked potentials (CEP) in 10 healthy volunteers (age range 21-34 yr). Esophageal and duodenal CEP had similar morphology in all subjects, whereas rectal CEP had two different but reproducible morphologies. The rectal CEP latency to the first component P1 (69 ms) was shorter than both duodenal (123 ms; P = 0.008) and esophageal CEP latencies (106 ms; P = 0.004). The duodenal CEP amplitude of the P1-N1 component (5.0 microV) was smaller than that of the corresponding esophageal component (5.7 microV; P = 0.04) but similar to that of the corresponding rectal component (6.5 microV; P = 0.25). This suggests that rectal sensation is either mediated by faster-conducting afferent pathways or that there is a difference in the orientation or volume of cortical neurons representing the different gut organs. In conclusion, the physiological and anatomic differences between gut organs are reflected in differences in the characteristics of their afferent pathways and cortical processing. PMID:12121880

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

    PubMed

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

    2015-12-15

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

  4. Visual evoked potentials to red-green stimulation in schoolchildren.

    PubMed

    Pompe, Manca Tekavcic; Kranjc, Branka Stirn; Brecelj, Jelka

    2006-01-01

    The aim is to study chromatic visual evoked potentials (VEP) to isoluminant red-green (R-G) stimulus in schoolchildren. Sixty children (7-19 years) with normal color vision were examined, 30 binocularly and 30 monocularly. The isoluminant point was determined for each child subjectively by using heterochromatic flicker photometry, and objectively from recordings. The stimulus was a 7 degrees circle composed of horizontal sinusoidal gratings, with spatial frequency 2 cycles/degrees and 90% contrast, presented in onset-offset mode. VEP were recorded from Oz (mid-occipital) position. Age-dependent waveform changes and changes of the positive and negative wave were studied to both binocular and monocular R-G stimulation. Age-dependent waveform changes were observed to binocular and monocular R-G stimulation. In younger children the positive wave was prominent, whereas in older children also the negative wave became more evident. The latency of the positive wave decreased linearly with age to R-G binocular stimulation. To monocular stimulation no significant changes of the latency were observed. The amplitude of the positive wave dropped exponentially with age to binocular and monocular stimulation. The latency of the negative wave increased linearly with age to binocular and monocular stimulation, whereas the amplitude did not show age-dependent changes. These findings suggest that the chromatic VEP response undergoes evident age-dependent changes during the school-age period. PMID:16961979

  5. Steady-state visual evoked potentials to computer monitor flicker.

    PubMed

    Lyskov, E; Ponomarev, V; Sandström, M; Mild, K H; Medvedev, S

    1998-05-01

    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, averaged and stored using Cadwell Excel EMG-EP recorder and a regression model was applied for the amplitude analysis. The mean values of S-VEP amplitude at 60 Hz were found to be significantly higher at 60 Hz refresh rate vs. 72 Hz (F1,12 = 14.1; P = 0.003). Effect of screen brightness (F2,24 = 6.5; e = 0.62; P = 0.00075) as well as the interaction effect of refresh rate and screen brightness (F2,24 = 11.6; P = 0.0003) were also found to be significant. Data obtained show that the characteristics of amplitude-modulated light from a computer monitor (frequency, brightness, waveform) are sufficient to elicit S-VEP, and the influence is not only restricted to the peripheral divisions of the visual system as it was shown earlier, but also extends to the central brain structures. PMID:9545663

  6. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

    PubMed Central

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Funada, Hideaki; Minoda, Haruka

    2014-01-01

    Purpose. To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT) screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account. PMID:25197652

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

    PubMed

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

    2016-07-15

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

  8. Visual Evoked Potentials in Guillain-Barré Syndrome

    PubMed Central

    Güngör, İnci; Öztürk, Hilal Eser; Onar, Musa Kazım

    2011-01-01

    Background and Purpose Guillain-Barré syndrome (GBS) is an acute demyelinating polyneuropathy with various clinical features. Optic neuritis occurs in rare cases. In this study we determined the incidence and patterns of visual evoked potential (VEP) abnormality in GBS in association with ophthalmologic findings. Methods Thirty-two patients with a diagnosis of GBS were included in the study. The correlation between pathologic VEPs and categories of neurologic deficit and electrophysiological findings were examined statistically. Results The patients ranged in age from 19 to 77 years. Five cases (16%) had abnormal VEPs. All five of these patients exhibited increased P100 latency differences between the two eyes. Other abnormalities were prolonged p100 latency, increased interocular amplitude difference, and distorted p100 configuration. Pathologic signs on ophthalmologic examination were observed in 80% of patients with abnormal VEPs. VEP abnormality was never present in pure axonal forms. There was no significant correlation between pathologic VEP and cerebrospinal fluid protein level or categories of neurologic deficits. Conclusions Involvement of the optic pathways is not a frequent finding in GBS. When present it is always asymmetric and generally accompanied with pathologic findings on ophthalmologic examination. VEPs may be abnormal in different clinical variants of GBS, and especially in demyelinating forms. PMID:21519525

  9. Motor evoked potential depression following repetitive central motor initiation.

    PubMed

    Kluger, Benzi M; Palmer, Candace; Shattuck, Johanna T; Triggs, William J

    2012-02-01

    Prior reports have described a transient and focal decline in transcranial magnetic stimulation (TMS)-induced motor evoked potential (MEP) amplitude following fatiguing motor tasks. However, the neurophysiological causes of this change in MEP amplitude are unknown. The aim of this study was to determine whether post-task depression of MEPs is associated with repetitive central motor initiation. We hypothesized that MEP depression is related to repeated central initiation of motor commands in task-related cortex independent of motor fatigue. Twenty healthy adults had MEPs measured from the dominant first dorsal interosseous (FDI) muscle before and after six different tasks: rest (no activity), contralateral fatiguing hand-grip, ipsilateral fatiguing hand-grip, contralateral finger tapping, ipsilateral finger tapping, and imagined hand-grip (motor imagery). Changes in MEPs from baseline were assessed for each task immediately following the task and at 2-min intervals until MEPs returned to a stable baseline. Measures of subjective effort and FDI maximum voluntary contractions (MVC) were also recorded following each task. A statistically significant drop in MEP amplitude was noted only with contralateral finger tapping and imagined grip. Changes in MEP amplitude did not correlate with subjective fatigue or effort. There was no significant change in FDI MVCs following hand-grip or finger-tapping tasks. This study extends our knowledge of the observed decline in MEP amplitude following certain tasks. Our results suggest that central initiation of motor programs may induce a change in MEP amplitude, even in the absence of objective fatigue. PMID:22130780

  10. The effect of heme oxygenase inhibition on visual evoked potentials.

    PubMed

    Savcioglu, Feyza; Akpinar, Deniz; Yargicoglu, Piraye; Agar, Aysel

    2009-01-01

    This study investigated the effect of heme oxygenase (HO) inhibition on visual evoked potentials (VEPs). HO catalyzes the oxidative degradation of heme. Products of HO reaction are biliverdin, ferrous iron, and carbon monoxide (CO). CO is a signal molecule and is an endogenous modulator in the soluble guanylate cyclase/cyclic guanosine monophosphate signaling pathway. Rats were treated with HO inhibitors tin protoporphyrin IX (SnPP IX) or zinc protoporphyrin IX (ZnPP IX) or HO inducer sodium arsenite (Na-arsenite). Soluble guanylate cyclase is inhibited by 1H-[1,2,3]oxydiazolo[4,3-a]quinoxalin-1-one (ODQ) and induced by 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1). VEPs were recorded under mild ether anesthesia with the help of stainless steel subdermal electrodes and a photic stimulator. SnPP IX, ODQ or SnPP IX + YC-1 injections significantly prolonged latencies of P3; however, Na-arsenite shortened latency of P3. It has been shown that HO affects VEPs. PMID:19922363

  11. Effect of immobilization and cold stress on visual evoked potentials.

    PubMed

    Yaras, Nazmi; Yargicoglu, Piraye; Agar, Aysel; Gumuslu, Saadet; Abidin, Ismail; Ozdemir, Semir

    2003-08-01

    The main aim of our research was to study the effects of immobilization and/or cold stress on amplitudes and latencies of visual evoked potentials (VEPs) and thiobarbituric acid reactive substances (TBARS). Forty healthy male albino rats, aged three months, were used. The rats were equally divided into four groups: Control group (C), the group exposed to cold stress (CS), the group exposed to immobilization stress (IS), and the group exposed to both cold and immobilization stress (CIS). Plasma corticosterone concentrations were significantly increased in all stress groups. Lipid peroxidation was increased in brain and retina of all stress groups as indicated by the significant increase in TBARS levels compared to the C group. Glutathione peroxidase (GSH-Px) activity in brain and retina increased in the CS group, but decreased in the IS group relative to the C group. GSH-Px activity also increased in the brain, but not in the retina in the CIS group with respect to the C group. The mean latencies of P1, N1, P2, N2, and P3 components were significantly prolonged in all stress groups compared with the C group. The results suggest that stress induced lipid peroxidation may influence VEPs. PMID:12888420

  12. An Intelligent Decision System for Intraoperative Somatosensory Evoked Potential Monitoring.

    PubMed

    Fan, Bi; Li, Han-Xiong; Hu, Yong

    2016-02-01

    Somatosensory evoked potential (SEP) is a useful, noninvasive technique widely used for spinal cord monitoring during surgery. One of the main indicators of a spinal cord injury is the drop in amplitude of the SEP signal in comparison to the nominal baseline that is assumed to be constant during the surgery. However, in practice, the real-time baseline is not constant and may vary during the operation due to nonsurgical factors, such as blood pressure, anaesthesia, etc. Thus, a false warning is often generated if the nominal baseline is used for SEP monitoring. In current practice, human experts must be used to prevent this false warning. However, these well-trained human experts are expensive and may not be reliable and consistent due to various reasons like fatigue and emotion. In this paper, an intelligent decision system is proposed to improve SEP monitoring. First, the least squares support vector regression and multi-support vector regression models are trained to construct the dynamic baseline from historical data. Then a control chart is applied to detect abnormalities during surgery. The effectiveness of the intelligent decision system is evaluated by comparing its performance against the nominal baseline model by using the real experimental datasets derived from clinical conditions. PMID:26415181

  13. Tibial somatosensory evoked potential can prognosticate for ambulatory function in subacute hemiplegic stroke.

    PubMed

    Hwang, Pyoungsik; Sohn, Min Kyun; Kim, Cuk-Seong; Jee, Sungju

    2016-04-01

    Early prediction of expected recovery in stroke can help in planning appropriate medical and rehabilitation interventions. Recovery of ambulation is one of the essential endpoints in stroke rehabilitation. However, the correlation of somatosensory evoked potentials (SSEP) with clinical parameters and their predictive significance are not clearly defined. We aimed to examine the association between tibial nerve SSEP and ambulatory outcomes in subacute hemiplegic stroke patients. We reviewed medical records for hemiplegic patients with first-ever stroke who received inpatient rehabilitation from January 2009 to May 2013. We excluded patients with diabetes mellitus, quadriplegia, bilateral lesions, brainstem lesions, those aged over 80years, and those with severe musculoskeletal problems. Tibial nerve SSEP were performed when they were transferred to the rehabilitation department. SSEP findings were divided into three groups; normal, abnormal and absent response. Berg balance scale and functional ambulation category (FAC) at discharge were compared with initial tibial SSEP findings using one-way analysis of variance. Thirty-one hemiplegic patients were included. Berg balance scale and FAC were significantly different according to the SSEP (P<0.001). Post hoc analysis showed a significant difference between normal and absent response in Berg balance scale (P<0.001) and FAC (P<0.001), and between abnormal and absent response in Berg balance scale (P=0.012) and FAC (P=0.019). Functional outcomes of the normal response group were better than the abnormal response group, but there was no statistical significance. These findings suggest that initial tibial nerve SSEP may be a useful biomarker for prognosticating functional outcomes in hemiplegic patients. PMID:26778357

  14. Dynamic properties of human visual evoked and omitted stimulus potentials.

    PubMed

    Bullock, T H; Karamürsel, S; Achimowicz, J Z; McClune, M C; Başar-Eroglu, C

    1994-07-01

    Visual evoked potentials (VEPs) and omitted stimulus potentials (OSPs) are re-examined in scalp recordings from 19 healthy subjects. The principal finding is a distinction in form, latency and properties between OSPs in the conditioning stimulus range < 2 Hz, used in previous human studies, and those in the range > 5 Hz, used in previous studies of selected elasmobranchs, teleost fish and reptiles. We cannot find OSPs between 2 and 5 Hz. The high frequency ("fast," ca.6- > 40 Hz) and the low frequency ("slow," ca. 0.3-1.6 Hz) OSPs have different forms and latencies but both tend to a constant latency after the omission, over their frequency ranges, suggesting a temporally specific expectation. Fast OSPs (typically N120, P170-230 and later components including induced rhythms at 10-13 Hz) resemble an OFF effect, and require fixation but not attention to the interstimulus interval. Slow OSPs (usually P500-1100) require attention but not fixation; they are multimodal, unlike the fast OSPs. Based on cited data from fish and reptiles, fast OSPs probably arise in the retina, to be modified at each subsequent level. We have no evidence on the origin of slow OSPs. In both ranges not only large, diffuse flashes, but weak, virtual point sources (colored LEDs) meters away suffice. They are difficult to habituate. Both require very short conditioning periods. The transition from the single, rested VEP to the steady state response (SSR) at different frequencies is described. Around 8-15 Hz in most subjects larger SSRs suggest a resonance. Alternation between large and small SSR amplitude occurs around 4 Hz in some subjects and conditions of attention, and correlates with an illusion that the flash frequency is 2 Hz or is irregular. Jitter of the conditioning intervals greatly reduces the slow OSP but only slightly affects the fast OSP. Differences between scalp loci are described. PMID:7517843

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

    PubMed

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

    2015-12-01

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

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

    PubMed

    Kent, Alexander R; Grill, Warren M

    2013-08-01

    Closed-loop deep brain stimulation (DBS) systems could provide automatic adjustment of stimulation parameters and improve outcomes in the treatment of Parkinson's disease and essential tremor. The evoked compound action potential (ECAP), generated by activated neurons near the DBS electrode, may provide a suitable feedback control signal for closed-loop DBS. The objectives of this work were to characterize the ECAP across stimulation parameters and determine the neural elements contributing to the signal. We recorded ECAPs during thalamic DBS in anesthetized cats and conducted computer simulations to calculate the ECAP of a population of thalamic neurons. The experimental and computational ECAPs were similar in shape and had characteristics that were correlated across stimulation parameters (R(2) = 0.80-0.95, P < 0.002). The ECAP signal energy increased with larger DBS amplitudes (P < 0.0001) and pulse widths (P < 0.002), and the signal energy of secondary ECAP phases was larger at 10-Hz than at 100-Hz DBS (P < 0.002). The computational model indicated that these changes resulted from a greater extent of neural activation and an increased synchronization of postsynaptic thalamocortical activity, respectively. Administration of tetrodotoxin, lidocaine, or isoflurane abolished or reduced the magnitude of the experimental and computational ECAPs, glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and D(-)-2-amino-5-phosphonopentanoic acid (APV) reduced secondary ECAP phases by decreasing postsynaptic excitation, and the GABAA receptor agonist muscimol increased the latency of the secondary phases by augmenting postsynaptic hyperpolarization. This study demonstrates that the ECAP provides information about the type and extent of neural activation generated during DBS, and the ECAP may serve as a feedback control signal for closed-loop DBS. PMID:23719207

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

    PubMed Central

    Kent, Alexander R.

    2013-01-01

    Closed-loop deep brain stimulation (DBS) systems could provide automatic adjustment of stimulation parameters and improve outcomes in the treatment of Parkinson's disease and essential tremor. The evoked compound action potential (ECAP), generated by activated neurons near the DBS electrode, may provide a suitable feedback control signal for closed-loop DBS. The objectives of this work were to characterize the ECAP across stimulation parameters and determine the neural elements contributing to the signal. We recorded ECAPs during thalamic DBS in anesthetized cats and conducted computer simulations to calculate the ECAP of a population of thalamic neurons. The experimental and computational ECAPs were similar in shape and had characteristics that were correlated across stimulation parameters (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

  18. Measurement of evoked potentials during thalamic deep brain stimulation

    PubMed Central

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

    2014-01-01

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

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

    PubMed

    Schmeisser, E T

    1985-10-01

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

  20. Visual Evoked Potentials in Infants with Diffuse Periventricular Leukomalacia.

    PubMed

    Carbajal-Valenzuela, Cintli Carolina; Santiago-Rodríguez, Efraín; Harmony, Thalía; Fernández-Bouzas, Antonio

    2014-03-10

    Periventricular leukomalacia (PVL) is characterized by necrosis of the cerebral white matter in the dorsolateral portions of the lateral ventricles. PVL causes motor, sensory, and cognitive deficits. The aim of this study was to analyze the conduction characteristics of the visual pathway in infants with diffuse PVL using visual evoked potentials (VEPs). We studied 11 healthy infants (mean age 3.3 ± 1.3 months) and 17 with diffuse PVL (mean age 2.9 ± 0.8 months and mean gestational age 31.9 ± 3.1 weeks). The N75, P100, and N135 wave latencies; the interwave N75-P100 and P100-N135 latencies; and the N75-P100 and P100-N135 amplitudes were measured in the occipital leads. VEPs were recorded during binocular stimulation at an angle of 120' from the Fz-Oz lead. Healthy children had mean N75, P100, and N135 wave latencies of 84.4 ± 5.8, 143.4 ± 30.6 and 222.9 ± 40.4 ms, respectively. The mean interwave N75-P100 and P100-N135 latencies were 59.0 ± 28.6 and 79.5 ± 13.6 ms, respectively. Compared with the healthy group, infants with PVL had longer N75 and N135 latencies at 92.3 ± 15.3 (P = .05) and 265.0 ms ± 60.3 (P = .05), respectively. The interwave latency P100-N135 (105.5 ± 29.1 ms; P = .017) was longer in children with PVL than in healthy infants. Infants with diffuse PVL had mild alterations in their N75, P100 and, particularly, their N135 latencies. These increases in P100-N135 interwave latencies could be because of damage to the geniculocortical pathways and V2-V3 networks. PMID:24615931

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

    PubMed

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

    2002-01-01

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

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

    PubMed

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

    2015-10-01

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

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

    PubMed

    Szlavik, Robert B

    2016-02-01

    The characterization of peripheral nerve fiber distributions, in terms of diameter or velocity, is of clinical significance because information associated with these distributions can be utilized in the differential diagnosis of peripheral neuropathies. Electro-diagnostic techniques can be applied to the investigation of peripheral neuropathies and can yield valuable diagnostic information while being minimally invasive. Nerve conduction velocity studies are single parameter tests that yield no detailed information regarding the characteristics of the population of nerve fibers that contribute to the compound-evoked potential. Decomposition of the compound-evoked potential, such that the velocity or diameter distribution of the contributing nerve fibers may be determined, is necessary if information regarding the population of contributing nerve fibers is to be ascertained from the electro-diagnostic study. In this work, a perturbation-based decomposition of compound-evoked potentials is proposed that facilitates determination of the fiber diameter distribution associated with the compound-evoked potential. The decomposition is based on representing the single fiber-evoked potential, associated with each diameter class, as being perturbed by contributions, of varying degree, from all the other diameter class single fiber-evoked potentials. The resultant estimator of the contributing nerve fiber diameter distribution is valid for relatively large separations in diameter classes. It is also useful in situations where the separation between diameter classes is small and the concomitant single fiber-evoked potentials are not orthogonal. PMID:26390494

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

    PubMed

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

    2013-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

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

    PubMed Central

    Cone, Barbara; Whitaker, Richard

    2013-01-01

    Objectives Cortical auditory evoked potentials (CAEPs) to tones and speech sounds were obtained in infants to: 1) further knowledge of auditory development above the level of the brainstem during the first year of life; 2) establish CAEP input-output functions for tonal and speech stimuli as a function of stimulus level and to 3) elaborate the data-base that establishes CAEP in infants tested while awake using clinically relevant stimuli, thus providing methodology that would have translation to pediatric audiological assessment. Hypotheses concerning CAEP development were that the latency and amplitude input-output functions would reflect immaturity in encoding stimulus level. In a second experiment, infants were tested with the same stimuli used to evoke the CAEPs. Thresholds for these stimuli were determined using observer-based psychophysical techniques. The hypothesis was that the behavioral thresholds would be correlated with CAEP input-output functions because of shared cortical response areas known to be active in sound detection. Design 36 infants, between the ages of 4-12 months (mean= 8 months, s.d.=1.8 months) and 9 young adults (mean age 21 years) with normal hearing were tested. First, CAEPs amplitude and latency input-output functions were obtained for 4 tone bursts and 7 speech tokens. The tone bursts stimuli were 50 ms tokens of pure tones at 0.5, 1.0, 2.0 and 4.0 kHz. The speech sound tokens, /a/, /i/, /o/, /u/, /m/, /s/, and /∫/, were created from natural speech samples and were also 50 ms in duration. CAEPs were obtained for tone burst and speech token stimuli at 10 dB level decrements in descending order from 70 dB SPL. All CAEP tests were completed while the infants were awake and engaged in quiet play. For the second experiment, observer-based psychophysical methods were used to establish perceptual threshold for the same speech sound and tone tokens. Results Infant CAEP component latencies were prolonged by 100-150 ms in comparison to adults. CAEP latency-intensity input output functions were steeper in infants compared to adults. CAEP amplitude growth functions with respect to stimulus SPL are adult-like at this age, particularly for the earliest component, P1-N1. Infant perceptual thresholds were elevated with respect to those found in adults. Furthermore, perceptual thresholds were higher, on average, than levels at which CAEPs could be obtained. When CAEP amplitudes were plotted with respect to perceptual threshold (dB SL), the infant CAEP amplitude growth slopes were steeper than in adults. Conclusions Although CAEP latencies indicate immaturity in neural transmission at the level of the cortex, amplitude growth with respect to stimulus SPL is adult-like at this age, particularly for the earliest component, P1-N1. The latency and amplitude input-output functions may provide additional information as to how infants perceive stimulus level. The reasons for the discrepancy between electrophysiologic and perceptual threshold may be due to immaturity in perceptual temporal resolution abilities and the broad-band listening strategy employed by infants. The findings from the current study can be translated to the clinical setting. It is possible to use tonal or speech sound tokens to evoke CAEPs in an awake, passively alert infant, and thus determine whether these sounds activate the auditory cortex. This could be beneficial in the verification of hearing aid or cochlear implant benefit. PMID:23722003

  7. Ocular Vestibular Evoked Myogenic Potentials Using Head Striker Stimulation

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    Introduction: Over the last two decades, several studies have been published on the impact of long-duration (i.e., 22 days or longer) spaceflight on the central nervous system (CNS). In consideration of the health and performance of crewmembers in flight and post-flight, we are conducting a controlled prospective longitudinal study to investigate the effects of spaceflight on the extent, longevity and neural bases of sensorimotor, cognitive, and neural changes. Multiple studies have demonstrated the effects of spaceflight on the vestibular system. One of the supporting tests conducted in this protocol is the Vestibular Evoked Myogenic Potential (VEMP) test that provides a unilateral measure of otolith (saccule and utricle) function. A different approach was taken for ocular VEMP (oVEMP) testing using a head striker system (Wackym et al. 2012). The oVEMP is generally considered to be a measure of utricle function. The the otolithic input to the inferior oblique muscle is predominately from the utricular macula. Thus, quantitatively, oVEMP tests utricular function. Another practical extension of these relationships is that the oVEMP reflects the superior vestibular nerve function. Methods: Ground testing was administered on 16 control subjects and for 8 subjects over four repeated sessions spanning 70 days. The oVEMP was elicitied via a hand held striker by a vibrotactile pulse presented at the rate of 1 Hz for 24 seconds on the side of the head as subjects lay supine on a gurney. Subjects were directed to gaze approximately 25 degrees above straight ahead in semi-darkness. For the oVEMP electromyograms will be recorded with active bipolar electrodes (Delsys Inc., Boston, MA) on the infra-orbital ridge 1 cm below the eyelid with a reference electrode on the below the knee cap. The EMG potentials were amplified; band-pass filtered using a BagnoliTM Desktop EMG System (Delsys Inc., Boston, MA, USA). This EMG signal is sampled at 10 kHz and the data stimulus onset to 100 MS was averaged over 24 trial repetitions for the vibrotactile VEMP. The typical oVEMP EMG response is an excitatory potential with first peak occurring at 11-12 ms and second peak at 18 ms. This requires a total recording time of approximately 29 seconds per trial which includes 5 seconds of no vibrotactile stimulation at the beginning of the protocol. The primary dependent measures consist of the latency and peak-to-peak amplitude from the EMG signals, which will be normalized to EMG levels at the beginning of the protocol. Data were collected for 3 repeated trials with striker stimulation on both the left and right side of the head Results: The oVEMP p1 range was observed at 3-14 ms and n1 at 7-19 ms. The striker system provided a consistent and rapid method for oVEMP testing. Discussion: Crew testing is in progress to determine changes in results between pre and post flight.

  8. 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 ...

  9. 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...

  10. Chromatic visual evoked potentials in young patients with demyelinating disease.

    PubMed

    Pompe, Manca Tekavčič; Brecelj, Jelka; Kranjc, Branka Stirn

    2014-04-01

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

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

    PubMed Central

    Lundy, Robert F.

    2009-01-01

    Among well-nourished populations, eating beyond homeostatic needs when presented with caloric-dense palatable food evidences the assertion that an increasing proportion of consumption is driven by pleasure, not just by the need for calories. This presents a major health crisis because the affective component of foods constitutes a behavioral risk factor that promotes over consumption [Sorensen, L.B., Moller, P., Flint, A., Martens, M., Raben, A., 2003. Effect of sensory perception of foods on appetite and food intake: a review of studies on humans. Int. J. Obes. Relat. Metab. Disord. 27, 11521166; Yeomans, M.R., Blundell, J.E., Leshem, M., 2004. Palatability: response to nutritional need or need-free stimulation of appetite? Br. J. Nutr. 92 (Suppl. 1), S3S14]. Overweight or obese individuals have an increased risk of developing hypertension, stroke, heart disease, chronic musculoskeletal problems, type-2 diabetes, and certain types of cancers [Hill, J.O., Catenacci, V., Wyatt, H.R., 2005. Obesity: overview of an epidemic. Psychiatr. Clin. N. Am. 28, 123, vii]. The etiology of obesity is complex involving genetic, metabolic, and behavioral factors, but ultimately results from long-term energy imbalance. Evidence indicates that learned and some forms of unlearned control of ingestive behavior driven by palatability (i.e. hedonic value) are critically dependent on reciprocal interactions between brainstem gustatory nuclei and the ventral forebrain. This review discusses the current understanding of centrifugal control of taste processing in subcortical gustatory nuclei and the potential role of such modulation in hedonic responding. PMID:18675299

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

    SciTech Connect

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

    1993-02-01

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

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

    PubMed

    Aminoff, M J

    1984-06-01

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

  14. What do evoked potentials tell us about the acoustic system of the harbor porpoise?

    NASA Astrophysics Data System (ADS)

    Bibikov, N. G.

    2004-05-01

    The evoked acoustic potentials of the brainstem (EAPB) were detected from the brain, the skull, and the surface of the head of the harbor porpoise ( Phocaena phocaena). Experiments were performed at the Karadag biological station (Crimea). Clicks, noise, and tone bursts of different frequencies within 80 190 kHz were used as stimuli. The time and frequency selectivities of the auditory system were estimated by the simultaneous and direct forward masking methods. The minima of EAPB thresholds were usually observed in a frequency range of 120 140 kHz, which corresponded to the main spectral maximum of the species-specific echolocation signal. In addition to the regular EAPB, a pronounced off-EAPB was observed. In the aforementioned frequency range, a frequency selectivity ( Q 10 of about 10) was revealed by the direct forward masking method. The EAPB could be measured up to a frequency of 190 kHz, but outside this high-resolution region (outside the ultrasonic “fovea”), the frequency selectivity was weak. A simultaneous masking of a click by a tone was strong only when the delay of the click with respect to the masker onset was smaller than 1.0 ms. In a continuous regime, the tone (unlike noise) produced only a weak masking. The response to a small intensity increment of 1 4 dB was rather strong. In the frequency range of 120 140 kHz, this response exhibited a nonmonotone dependence on the signal level. The time resolving power, which was measured by the EAPB recovery functions for double clicks of various levels, was rather high, even when the intensity of the test signal was 18 dB lower than the masker level. Experimental data show that the auditory system of the harbor porpoise is tuned to detecting ultrasonic echo signals in the frequency range within 120 140 kHz. A hypothesis is put forward that the acoustic system of the harbor porpoise allows the animal, from analyzing echo signals, to estimate not only the distance to the target and the target’s intrinsic properties but also the speed with which the target is approached, the latter estimate being presumably obtained on the basis of the Doppler effect.

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

    PubMed

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

    2015-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

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

    PubMed Central

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

    2014-01-01

    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

  18. The speech evoked potential in normal subjects and patients with cerebral hemispheric lesions.

    PubMed

    Pratap, R C

    1987-01-01

    The present study deals with observations on the "speech evoked potential"-a late positive potential evoked by word repetition. These potentials, evoked by "silent" repetition of polysyllabic words, were averaged and recorded from the scalp overlying the inferior frontal regions on both sides in 20 normal healthy subjects of ages ranging from 13-58 years. The potential had a triphasic negative, positive, negative morphology and was present over both hemispheres in left as well as right handed subjects. The main positive deflection and mean latencies of 219.2 msec and 221.6 msec and mean amplitude of 6.2 muv and 6.5 muv respectively on the left and right sides. Though there were interindividual variations in latency, amplitude and morphology, there was a high degree of intraindividual similarity and reproducibility in subjects. The variations in these parameters with age, sex and handedness are discussed. In 10 patients with cerebral lesions, the evoked potential was normal in 5 cases with right frontal lesions and showed abnormalities in 3 of 5 cases with left frontal lesions. The speech evoked potential may be useful in the further study of electrical correlates of speech output in speech disorders. PMID:3690926

  19. Evoked potential analysis: on-line signal optimization using a mini-computer.

    PubMed

    Hartwell, J W; Erwin, C W

    1976-10-01

    An automated computer-based system is described for the analysis of evoked potentials. All procedures are carried out in real-time A small computer performs the following functions; timing of random stimulus presentation, rejection of artifact contaminated responses, collection of digital data, computation of averaged evoked responses, computation of the Wiener filter, storage of the filtered and unfiltered averages and display of the resultant averages. The Wiener filter as described by Walter (1969) and Doyle (1975) is used to improve the estimate of the evoked potential by discriminating against frequencies likely to be contaminated with noise. The defining equation for the Wiener filter states that information at any frequency is to be weighted by the ratio of the power known to be in the signal (response) at that frequency over the corresponding power known to be in both the signal (response) and the noise (background EEG) at the same frequency. The technique requires the computation of the Fourier transform for each response in order to produce the power spectra necessary for the Wiener filter. Earlier reports dealing with this technique have usee large computers to analyze the evoked potential data off-line. The system described here allows for greater routine utilization of this powerful technique and the concomitant automated rejection of artifact contaminated responses. Highly improved estimates of the evoked potential are resultant using a minimal number of stimuli. PMID:60229

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

    PubMed Central

    Lucas, M G; Thomas, D G

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

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

    PubMed

    Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan

    2014-01-01

    Binaural beat (BB) illusions are experienced as continuous central pulsations when two sounds with slightly different frequencies are delivered to each ear. It has been shown that steady-state auditory evoked potentials (AEPs) to BBs can be captured and investigated. The authors recently developed a new method of evoking transient AEPs to binaural beats using frequency modulated stimuli. This methodology was able to create single BBs in predetermined intervals with varying carrier frequencies. This study examines the effects of the BB duration and the frequency modulating component of the stimulus on the binaural beats and their evoked potentials. Normal hearing subjects were tested with a set of four durations (25, 50, 100, and 200 ms) with two stimulation configurations, binaural dichotic (binaural beats) and diotic (frequency modulation). The results obtained from the study showed that out of the given durations, the 100 ms beat, was capable of evoking the largest amplitude responses. The frequency modulation effect showed a decrease in peak amplitudes with increasing beat duration until their complete disappearance at 200 ms. Even though, at 200 ms, the frequency modulation effects were not present, the binaural beats were still perceived and captured as evoked potentials. PMID:25571013

  4. Monitoring of somatosensory and motor evoked potentials during open reduction and internal fixation of pelvis and acetabular fractures.

    PubMed

    Arrington, E D; Hochschild, D P; Steinagle, T J; Mongan, P D; Martin, S L

    2000-10-01

    Monitoring of motor and somatosensory evoked potentials provides instantaneous intraoperative assessment of a patient's neurologic status. Monitoring of the sciatic nerve through motor and somatosensory evoked potentials can be used during open reduction and internal fixation of pelvic and acetabular fractures. A review of 12 pelvic and acetabular fractures treated with open reduction and internal fixation was conducted and assessed with a combination of intraoperative motor and somatosensory evoked potential monitoring. Results revealed intraoperative motor evoked potential monitoring was 100% sensitive and 100% specific in predicting postoperative sciatic nerve deficits, whereas somatosensory evoked potentials were not accurate in predicting postoperative sciatic nerve deficits. Combined monitoring of the sciatic nerve with motor and somatosensory evoked potentials is beneficial at predicting postoperative sciatic nerve deficits during open reduction and internal fixation of pelvic and acetabular fractures. PMID:11045555

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

    PubMed

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

    2000-09-01

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

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

    PubMed

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

    2015-10-01

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

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

    PubMed Central

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

    2013-01-01

    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 rats 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

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

    PubMed

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

    1990-01-01

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

  9. 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

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

    2010-10-13

    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 naïve and inflamed conditions. PMID:20643195

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

    PubMed

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

    2016-03-01

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

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

    PubMed Central

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

    2014-01-01

    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

  12. 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...

  13. Forced-Choice Preferential Looking and Visual Evoked Potential Acuities of Visually Impaired Children.

    ERIC Educational Resources Information Center

    Bane, M. C.; Birch, E. E.

    1992-01-01

    As follow up to a study which compared forced-choice preferential looking (FPL) with pattern visual evoked potential (VEP), this study increased the VEP success rate and improved agreement between the FPL and VEP acuity estimates by using horizontal bar stimuli for young preverbal children (n=17) with nystagmus. (Author/DB)

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

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

    ERIC Educational Resources Information Center

    Yanagihara, Masafumi; Sako, Akihito

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

  16. 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...

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

    EPA Science Inventory

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

  18. 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...

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

    ERIC Educational Resources Information Center

    Bates, Tim; And Others

    1995-01-01

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

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  2. Visual evoked potentials in hypothyroid and hyperthyroid patients before and after achievement of euthyroidism.

    PubMed

    Avramides, A; Papamargaritis, K; Mavromatis, I; Saddic, G; Vyzantiadis, A; Milonas, I

    1992-11-01

    Thyroid hormone deficiency is frequently associated with central nervous system (CNS) disturbances such as mental retardation, convulsions, coma etc. Studies of quantitative changes in CNS in hypo- or hyperthyroidism are scarce. Evoked potentials is a good method of assessing the electrical response of the brain to different (visual, acoustic, somatosensory) stimuli and has been used extensively in the study of brain disturbances and to a lesser degree in metabolic diseases. We studied the visual evoked potentials (latency and amplitude) in 12 patients with hyperthyroidism and 15 patients with hypothyroidism, before treatment and after they became euthyroid. Four of the hyperthyroids (33%) had abnormally prolonged (> 104 msec) latencies before therapy. Two of them had clinical exophthalmos. No change was observed after euthyroidism was achieved. On the contrary 7 out of 15 (47%) hypothyroids had abnormally prolonged latencies which became normal in 4 when euthyroidism was achieved. Amplitude was lower than normal in 6 and became normal only in one of them after treatment. None of the hyperthyroid patients had amplitude changes. In conclusion, hypothyroid patients may have changes in the amplitude and/or the latency of visual evoked potentials which are reversible to a great extent with thyroxine. Evoked potentials is another method of studying in humans the metabolic effects of thyroxine deficiency in CNS. PMID:1491123

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

    ERIC Educational Resources Information Center

    Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

    2009-01-01

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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  5. Influence of Rotating Shift Work on Visual Reaction Time and Visual Evoked Potential

    PubMed Central

    N, Krishnamurthy; A, Saravanan

    2014-01-01

    Background: The present day life style is changing the circadian rhythm of the body especially in rotating night shift workers. The impact of this prolongs their reaction time. Night shift also interferes with the circadian variation of pupil size which may affect the visual evoked potential. Aim: To compare the visual reaction time, visual evoked potential (VEP) in rotating night shift workers & day workers and also to correlate the changes in visual reaction time with visual evoked potential. Materials and Methods: Forty healthy male security guards & staff (25 35 y) who did rotating night shifts at least for six months & 40 d workers (25 35 y) who did not do night shift in last two years were involved in the study. Visual reaction time and the latency & amplitude of VEP were recorded. Result: Kolmogorov- Smirnov test for normalcy showed the latencies & amplitude of VEP to be normally distributed. Students unpaired t test showed significant difference (p<0.05) in the visual time and in the latencies of VEP between night shift & day workers. There was no significant difference in the amplitude of VEP. Conclusion: Night shift workers who are prone to circadian rhythm alteration will have prolonged visual reaction time & visual evoked potential abnormalities. Implementation of Bright Light Therapy would be beneficial to the night shift worker. PMID:25478332

  6. Potential Long Term Benefits of Acute Hypothermia after Spinal Cord Injury: Assessments with Somatosensory Evoked Potentials

    PubMed Central

    Maybhate, Anil; Hu, Charles; Bazley, Faith A.; Yu, Qilu; Thakor, Nitish V.; Kerr, Candace L.; All, Angelo H.

    2011-01-01

    Objective Neuroprotection by hypothermia has been an important research topic over last two decades. In animal models of spinal cord injury (SCI), the primary focus has been assessing effects of hypothermia on behavioral and histological outcomes. While a few studies have investigated electrophysiological changes in descending motor pathways with motor evoked potentials recorded during cooling, we report here, hypothermia induced increased electrical conduction in the ascending spinal cord pathways with somatosensory evoked potentials (SSEPs) in injured rats. In our experiments these effects lasted long after the acute hypothermia and were accompanied with potential long term improvements in motor movement. Design Laboratory Investigation. Setting University Medical School. Subjects 21 Female Lewis Rats. Interventions Hypothermia. Measurements and Main Results All animals underwent spinal cord contusion, with the NYU-Impactor, by a 12.5mm weight drop at thoracic vertebra T8. A group (n=10) was randomly assigned for a systemic 2hr. hypothermia episode (32±0.5°C) initiated ~2.0hrs post-injury. 11 rats were controls with post-injury temperature maintained at 37±0.5°C for 2hrs. The two groups underwent pre-injury, weekly post-injury (up to 4wks) SSEP recordings and standard motor behavioral tests (BBB). Three randomly selected rats from each group were euthanized for histological analysis at post-injury Day 3 and Day 28. Compared to controls, the hypothermia group showed significantly higher SSEP amplitudes post-injury; with longer latencies. The BBB scores were also higher immediately after injury and 4 weeks later in the hypothermia group. Importantly, specific changes in the BBB scores in hypothermia group (not seen in controls) indicated regained functions critical for motor control. Histological evaluations showed more tissue preservation in hypothermia group. Conclusions Post-SCI, early systemic hypothermia provided significant neuroprotection weeks after injury via improved sensory electrophysiological signals in rats. This was accompanied by higher motor behavioral scores and more spared tissue in acute and post-acute periods after injury. PMID:22001581

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

    PubMed Central

    2011-01-01

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

  8. Value of somatosensory evoked potentials in saphenous entrapment neuropathy.

    PubMed Central

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

    1992-01-01

    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

  9. Self-modeling structure of evoked postsynaptic potentials.

    PubMed

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

    2006-07-01

    With the simplicity of the synaptic structure and physiology at neuromuscular junctions (NMJs) of crayfish and the given transmitter being released in quantal packets, a detailed assessment in the fundamental processes of chemical synaptic transmission is possible. Since the quantal event is the basic element of transmission, we consider an approach to further understand the characteristics of quantal responses. In this study, we introduce a method for combining information across excitatory postsynaptic potentials (EPSPs) that are quantal in nature. The method is called self-modeling regression, known in the statistics literature as SEMOR. This method illustrates that the differing timing and heights of EPSPs can be described with four coefficients measuring affine (shift and scale) transformations of the x and y axes. We demonstrate that this relationship allows us to provide a unified schema for the many functionals currently used in the literature, such as peak amplitude, tau, latency, area under the curve, or decay time. Computer code in R is available on the internet to perform the analysis. PMID:16575851

  10. Maturation of Peripheral and Brainstem Auditory Function in the First Year Following Perinatal Asphyxia: A Longitudinal Study.

    ERIC Educational Resources Information Center

    Jiang, Ze D.

    1998-01-01

    A study of 44 infants who suffered asphyxia during the perinatal period examined the influence of perinatal asphyxia on the maturation of auditory pathways by serial recordings of the brainstem auditory evoked potentials (BAEP). The general maturational course of the BAEP following asphyxia was similar to a control group. (Author/CR)

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    The effect of task relevance on P3 (waveform of human evoked potential) waves and the methodologies used to deal with them are outlined. Visual evoked potentials (VEPs) were recorded from normal adult subjects performing in a visual discrimination task. Subjects counted the number of presentations of the numeral 4 which was interposed rarely and randomly within a sequence of tachistoscopically flashed background stimuli. Intrusive, task-irrelevant (not counted) stimuli were also interspersed rarely and randomly in the sequence of 2s; these stimuli were of two types: simples, which were easily recognizable, and novels, which were completely unrecognizable. It was found that the simples and the counted 4s evoked posteriorly distributed P3 waves while the irrelevant novels evoked large, frontally distributed P3 waves. These large, frontal P3 waves to novels were also found to be preceded by large N2 waves. These findings indicate that the P3 wave is not a unitary phenomenon but should be considered in terms of a family of waves, differing in their brain generators and in their psychological correlates.

  12. Giant pseudoaneurysm originated from distal middle cerebral artery dissection treated by trapping under sensitive evoked potential and motor evoked potential monitoring: Case report and discussion

    PubMed Central

    Gripp, Daniel Andrade; Nakasone, Fábio Jundy; Maldaun, Marcos Vinícius Calfat; de Aguiar, Paulo Henrique Pires; Mathias, Luis Roberto

    2016-01-01

    Background: Dissecting giant pseudoaneurysm of the middle cerebral artery (MCA) is a rare lesion often presenting challenges to neurosurgical teams dealing with this specific pathology. Giant pseudoaneurysm originating from a dissecting distal segment of the MCA treated with aneurysm trapping under motor and sensitive evoked potential monitoring with a successful outcome is presented in the article followed by a brief discussion on the subject. Case Description: A case of a previously healthy young female patient admitted at the emergency room of Santa Paula Hospital with a history of a sudden headache and syncope, dysphasia, and Grade 4 right hemiparesis due to a large brain hemorrhage secondary to a 25 mm ruptured pseudoaneurysm originated from a distal left MCA dissecting segment is described. Because the patient risked neurological worsening, aneurysm was treated with parent and efferent vessel trapping technique and no changes on the sensitive and motor evoked potential (MEP) from baseline informed on this decision. Hemorrhage was completely drained after aneurysm was secured. Conclusion: Neurophysiological sensitive and MEP monitoring, on this specific case was a valuable tool and informed on the decision of trapping of this large vascular lesion. PMID:27127710

  13. Steady-State Somatosensory Evoked Potential for Brain-Computer Interface—Present and Future

    PubMed Central

    Ahn, Sangtae; Kim, Kiwoong; Jun, Sung Chan

    2016-01-01

    Brain-computer interface (BCI) performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials (SSVEPs) seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP) BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed. PMID:26834611

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

    SciTech Connect

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

    1982-12-01

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

  15. Steady-state evoked potentials possibilities for mental-state estimation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  16. Lower brainstem dysfunction in an infant with persistent primitive trigeminal artery.

    PubMed

    Okanishi, Tohru; Saito, Yoshiaki; Miki, Shiho; Nagaishi, Jun-Ichi; Hanaki, Keiichi; Tomita, Yutaka; Fukuda, Chisako; Fujii, Shinya; Fujiwara, Kazunori; Kawamoto, Katsuyuki; Hata, Fumiko; Maegaki, Yoshihiro; Ohno, Kousaku

    2007-04-01

    A 6-month-old boy with persistent primitive trigeminal artery (PPTA) presented with stridor, dysphagia, delayed motor development and postural neck and shoulder dystonia. Magnetic resonance imaging/angiography and ultrasonography revealed PPTA, with flow from the dilated basilar artery to the right internal carotid artery, lower brainstem compression by the dilated basilar artery, and cerebellar vermis hypoplasia. Evoked potentials showed lower pons and medulla oblongata functional disruption. These lesions may be related to vascular etiology in the lower brainstem or to congenital malformation syndrome involving infratentorial structures. The relationship of this condition to Möbius syndrome is discussed. PMID:17008040

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    1987-01-01

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

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

    PubMed

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

    2016-03-01

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

  20. Latencies of evoked potentials to flicker and to pattern speedily estimated by simultaneous method.

    PubMed

    Regan, D

    1976-06-01

    This note describes a method for rapidly measuring the latency of a steady-state visual evoked potential (EP). Three sinewaves of different frequencies (F1, F2 and F3 c/sec) are summed, and the resulting waveform modulates either light intensity (for flicker stimulation) or spatial contrast (for pattern stimulation). Three evoked potentials of frequencies F1, F2 and F3 c/sec respectively are stimultaneously recorded by running three Fourier analysers in parallel. The outputs of the three analysers are presented in a single polar plot so as directly to display the three values of EP amplitude and phase. Practical methods for generating the pattern and flicker stimuli are described. PMID:57051

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

    PubMed Central

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

    2016-01-01

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

  2. Long latency auditory evoked potentials in children with cochlear implants: systematic review.

    PubMed

    Silva, Liliane Aparecida Fagundes; Couto, Maria Inês Vieira; Matas, Carla Gentile; Carvalho, Ana Claudia Martinho de

    2013-11-25

    The aim of this study was to analyze the findings on Cortical Auditory Evoked Potentials in children with cochlear implant through a systematic literature review. After formulation of research question and search of studies in four data bases with the following descriptors: electrophysiology (eletrofisiologia), cochlear implantation (implante coclear), child (criança), neuronal plasticity (plasticidade neuronal) and audiology (audiologia), were selected articles (original and complete) published between 2002 and 2013 in Brazilian Portuguese or English. A total of 208 studies were found; however, only 13 contemplated the established criteria and were further analyzed; was made data extraction for analysis of methodology and content of the studies. The results described suggest rapid changes in P1 component of Cortical Auditory Evoked Potentials in children with cochlear implants. Although there are few studies on the theme, cochlear implant has been shown to produce effective changes in central auditory path ways especially in children implanted before 3 years and 6 months of age. PMID:24626971

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

    PubMed

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

    1987-11-01

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

  4. Evaluation of early motor and sensory evoked potentials in cervical spinal cord injury.

    PubMed

    Chéliout-Héraut, F; Loubert, G; Masri-Zada, T; Aubrun, F; Pasteyer, J

    1998-02-01

    To determine the efficacy of motor evoked potentials (MEP) and sensory evoked potentials (SEP) in the assessment of severe cervical injury, 17 subjects with severe cervical injury were studied. During the 1st week post-injury and post-surgical treatment, all subjects were submitted to electromyogram (EMG) recordings, dermatomal somatosensory evoked potentials (D.SEP), posterior tibial nerve somatosensory evoked potentials (PTN.SEP), MEP and bilateral cervical electrical stimulations with recording of the diaphragm. For the D.SEP, the latencies of the N9 and N20 responses and the conduction time (N9-N20) were measured in the upper limbs; the latencies of the P40 and P60 responses were measured in the lower limbs. MEP were recorded from distal upper and lower limb muscles following transcranial electrical stimulation of the cortex. (Magnetic stimulation was not indicated because of implanted metallic material in the cervical skull of many patients.) A SEP and MEP grading system was used to improve the assessment of different root neurological levels. In patients with incomplete lesions PTN.SEP, D.SEP and MEP responses could be recorded in territories that were clinically deficient. Patients with complete lesions and absent SEP and MEP responses had a poor outcome. A good correlation was found between the severity of the spinal cord injury and SEP grading. For MEP, the presence or absence of intercostal responses (C4) to cervical and cortical stimulation was the best prognostic indicator. The combined electrophysiological exploration of MEP and SEP proved to be a useful tool for monitoring patients with severe spinal cord injury. PMID:9562998

  5. Evoked potential correlates of selective attention with multi-channel auditory inputs

    NASA Technical Reports Server (NTRS)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  6. Evaluation of transducers for obtaining intraoperative short-latency auditory evoked potentials.

    PubMed

    Erwin, C W; Gulevich, S J

    1985-08-01

    Operative monitoring of short-latency auditory evoked potentials during posterior fossa surgery requires audio transducers of small physical size so as to not interfere with the operative field. There are many relatively inexpensive transducers in the commercial audio hifi market of appropriate size. Some produce suitable biological responses and tolerate long term use without failure. The authors describe factors to consider and methods used in testing such transducers. PMID:2410230

  7. A portable device for recording evoked potentials, optimized for pattern ERG.

    PubMed

    McInturff, Stephen P; Buchser, William J

    2016-02-01

    Recording evoked potentials in un-anesthetized animals and people is a powerful technique to non-invasively measure the function of neurons. As such, the primary output neurons of the eye can be assessed by the pattern electroretinogram (PERG). Currently, electro-physiologic setups to perform PERG or related recordings are costly, complicated, and non-portable. Here, we design a simple steady-state PERG system, based off an Arduino board. The amplifier is built on a shield that fits over a microcontroller board, an Arduino, which digitizes the signal and sends it to a computer that presents stimuli then records and analyzes the evoked potentials. We used the device to record PERG accurately with a sensitivity as low as half a microvolt. The device has also been designed to implement other evoked potential recordings. This simple device can be quickly constructed and used for experiments in moving systems. Additionally, this device can be used to expose students in underserved areas to research technology that they would otherwise not have access to. PMID:26536572

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

    PubMed

    Voss, Logan J; Sleigh, James W

    2015-12-01

    Despite their ubiquitous use for rendering patients unconscious for surgery, our understanding of how general anesthetics cause hypnosis remains rudimentary at best. Recent years have seen increased interest in "top-down" cortico-centric theories of anesthetic action. The aim of this study was to explore this by investigating direct cortical effects of anesthetics on cerebrocortical evoked potentials in isolated mouse brain slices. Evoked potentials were elicited in cortical layer IV by electrical stimulation of the underlying white matter. The effects of three anesthetics (ketamine, etomidate, and isoflurane) on the amplitude, latency, and slope of short-latency evoked potentials were quantified. The N2/P3/N4 potentials–which represent the early cortical response–were enhanced by etomidate (increased P3-N4 slope, P <0.01), maintained by ketamine, and reduced by isoflurane (lower N2/P3 amplitude, P <0.01). These effects closely resemble those seen in vivo for the same drugs and point to a cortical mechanism independent of effects on subcortical structures such as the thalamus. PMID:26480876

  9. Four-limb muscle motor evoked potential and optimized somatosensory evoked potential monitoring with decussation assessment: results in 206 thoracolumbar spine surgeries

    PubMed Central

    Al Zayed, Zayed; Al Saddigi, Abdulmoneam

    2007-01-01

    The objective of this study was to improve upon leg somatosensory-evoked potential (SEP) monitoring that halves paraplegia risk but can be slow, miss or falsely imply motor injury and omits arm and decussation assessment. We applied four-limb transcranial muscle motor-evoked potential (MEP) and optimized peripheral/cortical SEP monitoring with decussation assessment in 206 thoracolumbar spine surgeries under propofol/opioid anesthesia. SEPs were optimized to minimal averaging time that determined feedback intervals between MEP/SEP sets. Generalized changes defined systemic alterations. Focal decrements (MEP disappearance and/or clear SEP reduction) defined neural compromise and prompted intervention. They were transient (quickly resolved) or protracted (>40 min). Arm and leg MEP/SEP monitorability was 100% and 98/97% (due to neurological pathology). Decussation assessment disclosed sensorimotor non-decussation requiring ipsilateral monitoring in six scoliosis surgeries (2.9%). Feedback intervals were 1–3 min. Systemic changes never produced injury regardless of degree. They were gradual, commonly included MEP/SEP fade and sometimes required large stimulus increments to maintain MEPs or produced >50% SEP reductions. Focal decrements were abrupt; their positive predictive value for injury was 100% when protracted and 13% when transient. Six transient arm decrements predicted one temporary radial nerve injury; five suggested arm neural injury prevention (2.4%). There were 15 leg decrements: six MEP-only, four MEP before SEP, three simultaneous and two SEP-only. Five were protracted, predicting four temporary cord injuries (three motor, one Brown–Sequard) and one temporary radiculopathy. Ten were transient, predicting one temporary sensory cord injury; nine suggested cord injury prevention (4.4%). Two radiculopathies and one temporary delayed paraparesis were unpredicted. The methods are reliable, provide technical/systemic control, adapt to non-decussation and improve spinal cord and arm neural protection. SEP optimization speeds feedback and MEPs should further reduce paraplegia risk. Radiculopathy and delayed paraparesis can evade prediction. PMID:17638028

  10. A visual study of surface potentials and Laplacians due to distributed neocortical sources: computer simulations and evoked potentials.

    PubMed

    Nunez, P L; Pilgreen, K L; Westdorp, A F; Law, S K; Nelson, A V

    1991-01-01

    A "picture book" of surface potentials, Laplacians, and magnetic fields due to distributed, neocortical sources is presented. The mathematically simulated data is based on 4200 current sources at the macrocolumn scale. Estimated scalp surface maps are based on the three-concentic spheres model of the head. Emphasis is placed on the effects of sampling with a limited number of electrodes, the choice of reference electrode, and the use of the spline Laplacian to improve spatial resolution. The spline Laplacian is applied to median and ulnar nerve somatosensory evoked potentials and to auditory evoked potentials including P300. Substantial improvement in spatial resolution over conventional methods is obtained. The implementation of practical high resolution EEG systems based on the spline Laplacian is considered. PMID:1793689

  11. Normative data for Aδ contact heat evoked potentials in adult population: a multicenter study.

    PubMed

    Granovsky, Yelena; Anand, Praveen; Nakae, Aya; Nascimento, Osvaldo; Smith, Benn; Sprecher, Elliot; Valls-Solé, Josep

    2016-05-01

    There has been a significant increase over recent years in the use of contact heat evoked potentials (CHEPs) for the evaluation of small nerve fiber function. Measuring CHEP amplitude and latency has clinical utility for the diagnosis and assessment of conditions with neuropathic pain. This international multicenter study aimed to provide reference values for CHEPs to stimuli at 5 commonly examined body sites. Contact heat evoked potentials were recorded from 226 subjects (114 females), distributed per age decade between 20 and 79 years. Temperature stimuli were delivered by a thermode (32°C-51°C at a rate of 70°C/s). In phase I of the study, we investigated side-to-side differences and reported the maximum normal side-to-side difference in Aδ CHEP peak latency and amplitude for leg, forearm, and face. In phase II, we obtained normative data for 3 CHEP parameters (N2P2 amplitude, N2 latency, and P2 latency), stratified for gender and age decades from face, upper and lower limbs, and overlying cervical and lumbar spine. In general, larger CHEP amplitudes were associated with higher evoked pain scores. Females had CHEPs of larger amplitude and shorter latency than males. This substantive data set of normative values will facilitate the clinical use of CHEPs as a rapid, noninvasive, and objective technique for the assessment of patients presenting with neuropathic pain. PMID:26907092

  12. Visual evoked potentials for attentional gating in a brain-computer interface.

    PubMed

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

    2012-01-01

    For synchronous brain-computer interface (BCI) paradigms tasks that utilize visual cues to direct the user, the neural signals extracted by the computer are representative of voluntary modulation as well as evoked responses. For these paradigms, the evoked potential is often overlooked as a source of artifact. In this paper, we put forth the hypothesis that cue priming, as a mechanism for attentional gating, is predictive of motor imagery performance, and thus a viable option for self-paced (asynchronous) BCI applications. We approximate attention by the amplitude features of visually evoked potentials (VEP)s found using two methods: trial matching to an average VEP template, and component matching to a VEP template defined using independent component analysis (ICA). Templates were used to rank trials that display high vs. low levels of fixation. Our results show that subject fixation, measured by VEP response, fails as a predictor of successful motor-imagery task completion. The implications for the BCI community and the possibilities for alternative cueing methods are given in the conclusions. PMID:23366247

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    The visual evoked potential (VEP) to rare, task-relevant (counted) numerical stimuli was compared with VEPs to rare, task-irrelevant stimuli, both being randomly interspersed within a sequence of tachistoscopically-flashed background numbers. These task-irrelevant stimuli were of two classes: (1) easily recognizable (e.g., simple geometric shapes) and (2) completely novel (i.e., complex, colorful abstract-type drawings which were unrecognizable). It was found that such novel stimuli did, in fact, evoke large P3 waves, but they had different scalp distributions from those which followed the task-relevant stimuli. This indicates that at least two types of late positive P3 waves exist, differing both in brain source and psychological correlates.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    1. Neural activity was recorded in hippocampal slices from euthermic chipmunks, hamsters and rats. 2. While recording the evoked potentials, the temperature of the Ringer's solution bathing the slice was varied by controlling the temperature of an outer chamber jacketing the recording chamber. 3. The temperature just below that at which a population spike could be evoked, Tt, was 10.4 +/- 0.3 degrees C (mean +/- SEM) for chipmunk slices, 14.1 +/- 0.4 degrees C for rat slices and 14.8 +/- 0.4 degrees C for hamster slices. Tt was significantly lower in the chipmunk slices (P<0.01) than in the rat and hamster slices. 4. Data were interpreted as consistent with the hypothesis that chipmunk hippocampal neurons are intrinsically cold resistant.

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

    PubMed Central

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

    2014-01-01

    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

  16. Cord dorsum potentials evoked by electroacupuncture applied to the hind limbs of rats.

    PubMed

    Quiroz-Gonzlez, Salvador; Segura-Alegra, Bertha; Guadarrama-Olmos, Jos Carlos; Jimnez-Estrada, Ismael

    2014-02-01

    The longitudinal distribution of the cord dorsum potentials (CDPs) produced by electroacupuncture (EA) stimulation at acupuncture points (APs) located on the hind limbs of rats was analyzed in this study. Single electrical pulses (0.05 ms, 1 Hz) applied to the bladder (BL) and the gallbladder (GB) APs produced CDPs on several spinal segments and were composed of the following four components: an afferent volley, two negative components (N1 and N2), and one positive component (P wave). The larger evoked CDPs differed in their rostrocaudal distributions depending on the stimulated AP site, with those evoked by GB32-33 (at L3) and GB36-37 (at L4) being more caudal than those generated by BL58-59 (at L5) and BL37-38 (at L6). The CDPs produced by stimulating nonacupoints (NAPs) showed similar components and rostrocaudal distributions that were smaller in amplitude than those evoked by stimulating APs. The CDPs produced by stimulating NAPs located on a meridian acupuncture area were similar in amplitude and longitudinal distribution to those produced by stimulating APs. Our results suggest that the specificity of EA stimulation for CDPs responses is mainly related to an activation of meridian pathways associated with peripheral nerve routes rather than to a restricted point specificity of APs. PMID:24513345

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

    PubMed

    Freye, Enno

    2005-04-01

    An evoked potential differs from the EEG mainly in two ways: 1. The EEG is a random, continuous signal, which arises from the ongoing activity of the outer layers of the cortex. An evoked potential is the brain's response to a repetitive stimulus along a specific nerve pathway. 2.EEG signals range from 10-200 milliVolt (mV). Evoked potentials are smaller in amplitude (1-5-20 microVolt requiring precise electrode positioning and special techniques (signal averaging) to extract the specific response from the underlying EEG "noise". The technique of signal averaging, as originally described by Dawson in 1954 [69J, has been further developed in computer processing. The technique is now used by applying a stimulus repeatedly--preferably at randomized intervals--and to record the evoked response over the corresponding area of the brain, averaging out mathematically the change over the number of stimuli. Rationale for the use of EPs in the OR and the ICU. Evoked potentials (EPs) serve the following major purposes: 1. Monitoring of the functional integrity of neural structures that may be at risk during, for instance, ECC (extracorporeal circulation) or endarterectomy indicating cerebral hypoxia. 2. Monitoring of the effects of anesthetic agents and other centrally active drugs, which, besides the cortex, affect deeper neuronal structures. 3. Orthopedic cases where the spinal cord is at risk such as Harrington rod insertion and removal. 4. Clamping of the abdominal aortic artery during aneurysmectomy resulting in a potential damage of the lower parts of the spinal cord. 5. Clipping of an intracerebral aneurysm, which may be impeding blood flow to vital cerebral textures. 6. An indicator of cerebral hypoxia when the blood pressure is deliberately lowered. 7. Operation on peripheral nerves and nerve roots to identify early trauma. 8. Monitoring the cerebral function during controlled hypothermia when the EEG becomes flat. 9. Monitoring of the pathophysiological conditions after severe head trauma and the effects of therapy. 10. An intraoperative warning device of unsuspected awareness during light anesthesia when movement is abolished by muscle relaxants and cardiovascular responses are modified by vasoactive drugs. In case of the latter the stimulus is a small electrical potential applied to the skin of the hand. Thereafter, the stimulus travels along the specific nervous pathways inducing (= generating) potential activation at various sites. The generation of potential changes at various sites along the pathway is an index for the integrity of the nerve. Thus, the evoked potential can be considered a neurophysiological response (usually of the cortex) to impulses originating from some externally stimulated sensory nerve. They provide a physiological measure of the functional integrity of the sensory nerve pathway, which can be used as a clinical diagnostic tool as well as for intraoperative monitoring. The evoked potential usually is recorded from the specific cortical area corresponding to the stimulus input. The classification of evoked potentials. Stimulating a sensory nervous pathway induces evoked potentials. If the auditory nerve is stimulated by "clicks" from headphones, it is called the auditory evoked potential (AEP). The early part of the AEP waveform (less than 10 msec) is called the Brainstem Auditory Evoked Potential (BAEP) since it reflects the passing of the impulse through the brainstem. If a nerve on the arm or the leg is stimulated by a small electrical current applied to the overlying skin, it is called the Somatosensory Evoked Potential (SSEP). If, however, the retina is stimulated by means of flicker light or a sudden change in a checkerboard pattern, the evoked potential thus recorded over the corresponding cortical area is called the Visual Evoked Potential (VEP). Evoked potentials are used both as a diagnostic tool and as a monitoring technique. As diagnostic tests, evoked potentials are useful to evaluate neurologic disorders such as: a) multiple sclerosis, b) acoustic nerve tumors, and c) optic neuritis. As a monitoring modality, evoked potentials are used during all surgical procedures, which might compromise part of the brain or the spinal cord. PMID:16167223

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

    NASA Astrophysics Data System (ADS)

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

    1994-07-01

    Several statistical procedures have been proposed as objective methods for determining evoked-potential thresholds. Data have been presented to support each of the methods, but there have not been direct comparisons using the same data. The goal of the present study was to evaluate correlation and variance ratio statistics using common data. A secondary goal was to evaluate the utility of a derived potential for determining thresholds. Chronic, bipolar electrodes were stereotaxically implanted in the inferior colliculi of six chinchillas. Evoked potentials were obtained at 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 kHz using 12-ms tone bursts and 12-ms tone bursts superimposed on 120-ms pedestal tones which were of the same frequency as the bursts, but lower in amplitude by 15 dB. Alternate responses were averaged in blocks of 200 to 4000 depending on the size of the response. Correlations were calculated for the pairs of averages. A response was deemed present if the correlation coefficient reached the 0.05 level of significance in 4000 or fewer averages. Threshold was defined as the mean of the level at which the correlation was significant and a level 5 dB below that at which it was not. Variance ratios were calculated as described by Elberling and Don (1984) using the same data. Averaged tone burst and tone burst-plus pedestal data were differenced and the resulting waveforms subjected to the same statistical analyses described above. All analyses yielded thresholds which were essentially the same as those obtained using behavioral methods. When the difference between stimulus durations is taken into account, however, evoked-potential methods produced lower thresholds than behavioral methods.

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

    PubMed

    Pascoli, Vincent; Turiault, Marc; Lüscher, Christian

    2012-01-01

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

  20. Intensity dependence of auditory evoked potentials during light interference in migraine.

    PubMed

    Ambrosini, Anna; Coppola, Gianluca; Grardy, Pierre-Yves; Pierelli, Francesco; Schoenen, Jean

    2011-04-01

    Migraine patients show interictally a strong intensity dependence of auditory evoked cortical potentials (IDAP) and a lack of habituation of evoked potentials. Photic drive on high-frequency flash stimulation is another well-known interictal feature in migraineurs, associated with alpha-rhythm hyper-synchronisation. We compared therefore the influence of light stimulation on IDAP in healthy volunteers (HV) and migraine patients. A continuous flash stimulation was delivered during the recording of auditory evoked potentials at suprathreshold increasing stimulation intensities. IDAP was measured as the amplitude/stimulus intensity function (ASF) slope. In HV, the ASF slope decreased during flash stimulation, whereas, on average, there was no significant change in migraineurs. A closer analysis of migraineurs disclosed two subgroups of patients with no detectable clinical differences: one, the largest, in which the ASF slope was normal at baseline, but increased during light stimulation, the other with an increased ASF slope at rest and a decrease during light interference. Visual sensory overload is able to increase IDAP in the majority of migraineurs, which contrasts with HV. We hypothesise that this could be due to hyper-synchronisation of the alpha rhythm because of photic drive and possibly thalamo-cortical dysfunction. A minority of migraineurs have, like HV, an IDAP reduction during light interference. They are, however, characterised, unlike most HV, by a high IDAP at baseline. Besides underscoring the pathophysiological heterogeneity of migraine, these results suggest that light interference might improve the phenotyping of migraine patients who have a normal IDAP in the resting condition. PMID:21281693

  1. Neuronal current magnetic resonance imaging of evoked potentials and neural oscillations

    NASA Astrophysics Data System (ADS)

    Jiang, Xia

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

  2. Auditory Evoked Potential Audiograms Compared with Behavioral Audiograms in Aquatic Animals.

    PubMed

    Sisneros, Joseph A; Popper, Arthur N; Hawkins, Anthony D; Fay, Richard R

    2016-01-01

    Auditory evoked potentials (AEPs) have become popular for estimating hearing thresholds and audiograms. What is the utility of these measurements? How do AEP audiograms compare with behavioral audiograms? In general, AEP measurements for fishes and marine mammals often underestimate behavioral thresholds, but comparisons are especially complicated when the AEP and behavioral measures are obtained under different acoustic conditions. There is no single representative relationship between AEP and behavioral audiograms and these audiograms should not be considered equivalent. We suggest that the most valuable comparisons are those made by the same researcher using similar acoustic conditions for both measurements. PMID:26611067

  3. A programmable rapid roll-off low pass filter for evoked potential and EEG recording.

    PubMed

    Dowman, R; Stockbridge, N

    1988-08-01

    The RF5609 rapid roll-off (-75 dB/octave) low pass filter has many features that make it ideal for evoked potential and EEG recording. The RF5609 is inexpensive, programmable, and can be turned off momentarily to eliminate large amplitude stimulus artifacts. Removal of these artifacts prevents ringing and hence allows a more rapid roll-off than can be easily achieved with conventional active analogue low pass filters such as Butterworth filter. Furthermore, the RF5609 low pass filter provides rapid roll-off and artifact suppression without the time or computing power requirements of digital low pass filters. PMID:3191416

  4. Histogram based quantification of spinal cord injury level using somatosensory evoked potentials.

    PubMed

    Mir, Hasan; Al-Nashash, Hasan; Kerr, Douglas; Thakor, Nitish; All, Angelo

    2010-01-01

    This paper uses an entropy based metric to study the somatosensory evoked potential (SEP) in rodents afflicted with focal demyelination spinal cord injury (SCI). It has been shown that amplitude characteristics of the SEP signal are a strong indicator of the integrity of the spinal cord sensory pathways. Compared to conventional correlation based metrics, the metric used in this paper exploits the amplitude histogram of SEP signals to provide a robust assessment of the different degrees of demyelination in the spinal cord. Results are presented using actual SEP signals collected on rodents with various levels of SCI. PMID:21096668

  5. Middle ear muscle contractions and their relation to pulse and echo evoked potentials in the bat

    NASA Technical Reports Server (NTRS)

    Henson, O. W., Jr.; Henson, M. M.

    1972-01-01

    An analysis is made of pulse and echo orientation cries of the Mustache Bat. That bat's cries are characterized by a long, 60 to 30 msec, pure tone component and brief beginning and terminal FM sweeps. In addition to obvious echo overlap and middle ear muscle contractions, the following are examined: (1) characteristics of pulse- and echo-evoked potential under various conditions, (2) evidence of changes in hearing sensitivity during and after pulse emission, and (3) the role of the middle ear muscles in bringing about these changes.

  6. Variability analysis of visual evoked potentials in humans by pattern recognition in phase domain.

    PubMed

    Achimowicz, J Z

    1995-01-01

    A novel approach to single trial visually evoked potentials (VEP) variability analysis based on a new model of post-stimulus brain electrical activity is presented. The convolution model introduced by the author is experimentally verified by the analysis of flash stimulus effects on EEG amplitude and phase spectra. Pattern recognition in the signal phase domain is proposed for detection of any time locked transient signals. This is illustrated by an application of a clustering algorithm in two-dimensional unwrapped phase of EEG Fourier transform space for occipitally recorded VEPs in human subjects. PMID:8553911

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

    PubMed Central

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

    2013-01-01

    Investigations into the biology of aquatic and semiaquatic species, including those involving sensory specialization, often require creative solutions to novel questions. We developed a technique for safely anesthetizing a semiaquatic chelonian species, the diamondback terrapin (Malaclemys terrapin), for measurement of auditory evoked potentials while animals were completely submerged in water. Custom-modified endotracheal tubes were used to obtain a watertight seal on both sides of the glottis and prevent aspiration of water during testing. No adverse effects were seen after the procedures, and assessment of venous blood-gas partial pressures and lactate concentrations indicated that sufficient gas exchange was maintained under anesthesia through manual ventilation. PMID:24351768

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

    PubMed Central

    Frizzo, Ana C. F.

    2015-01-01

    The information presented in this paper demonstrates the author’s experience in previews cross-sectional studies conducted in Brazil, in comparison with the current literature. Over the last 10 years, auditory evoked potential (AEP) has been used in children with learning disabilities. This method is critical to analyze the quality of the processing in time and indicates the specific neural demands and circuits of the sensorial and cognitive process in this clinical population. Some studies with children with dyslexia and learning disabilities were shown here to illustrate the use of AEP in this population. PMID:26113833

  9. Control of humanoid robot via motion-onset visual evoked potentials.

    PubMed

    Li, Wei; Li, Mengfan; Zhao, Jing

    2014-01-01

    This paper investigates controlling humanoid robot behavior via motion-onset specific N200 potentials. In this study, N200 potentials are induced by moving a blue bar through robot images intuitively representing robot behaviors to be controlled with mind. We present the individual impact of each subject on N200 potentials and discuss how to deal with individuality to obtain a high accuracy. The study results document the off-line average accuracy of 93% for hitting targets across over five subjects, so we use this major component of the motion-onset visual evoked potential (mVEP) to code people's mental activities and to perform two types of on-line operation tasks: navigating a humanoid robot in an office environment with an obstacle and picking-up an object. We discuss the factors that affect the on-line control success rate and the total time for completing an on-line operation task. PMID:25620918

  10. Control of humanoid robot via motion-onset visual evoked potentials

    PubMed Central

    Li, Wei; Li, Mengfan; Zhao, Jing

    2015-01-01

    This paper investigates controlling humanoid robot behavior via motion-onset specific N200 potentials. In this study, N200 potentials are induced by moving a blue bar through robot images intuitively representing robot behaviors to be controlled with mind. We present the individual impact of each subject on N200 potentials and discuss how to deal with individuality to obtain a high accuracy. The study results document the off-line average accuracy of 93% for hitting targets across over five subjects, so we use this major component of the motion-onset visual evoked potential (mVEP) to code people's mental activities and to perform two types of on-line operation tasks: navigating a humanoid robot in an office environment with an obstacle and picking-up an object. We discuss the factors that affect the on-line control success rate and the total time for completing an on-line operation task. PMID:25620918

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

    PubMed

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

    2012-07-01

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

  12. Exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    Objective. The steady-state visual evoked potential (SSVEP) is an electroencephalographic response to flickering stimuli generated partly in primary visual area V1. The typical ‘cruciform’ geometry and retinotopic organization of V1 is such that certain neighboring visual regions project to neighboring cortical regions of opposite orientation. Here, we explored ways to exploit this organization in order to boost scalp SSVEP amplitude via oscillatory summation. Approach. We manipulated flicker-phase offsets among angular segments of a large annular stimulus in three ways, and compared the resultant SSVEP power to a conventional condition with no temporal phase offsets. (1) We divided the annulus into standard octants for all subjects, and flickered upper horizontal octants with opposite temporal phase to the lower horizontal ones, and left vertical octants opposite to the right vertical ones; (2) we individually adjusted the boundaries between the eight contiguous segments of the standard octants condition to coincide with cruciform-consistent, early-latency topographical shifts in pattern-pulse multifocal visual-evoked potentials (PPMVEP) derived for each of 32 equal-sized segments; (3) we assigned phase offsets to stimulus segments following an automatic algorithm based on the relative amplitudes of vertically- and horizontally-oriented PPMVEP components. Main results. The three flicker-phase manipulations resulted in a significant enhancement of normalized SSVEP power of (1) 202%, (2) 383%, and (3) 300%, respectively. Significance. We have thus demonstrated a means to obtain more reliable measures of visual evoked activity purely through consideration of cortical geometry. This principle stands to impact both basic and clinical research using SSVEPs.

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

    PubMed

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

    2012-09-01

    An evoked-potential audiogram was measured for an Indo-Pacific humpback dolphin (Sousa chinensis) living in the dolphinarium of Nanning Zoo, China. Rhythmic 20 ms pip trains composed of cosine-enveloped 0.25 ms tone pips at a pip rate of 1 kHz were presented as sound stimuli. The dolphin was trained to remain still at the water surface and to wear soft latex suction-cup EEG electrodes used to measure the animal's envelope-following evoked potentials to the sound stimuli. Responses to 1000 rhythmic 20 ms pip trains for each amplitude/frequency combination were averaged and analysed using a fast Fourier transform to obtain an evoked auditory response. The hearing threshold was defined as the zero crossing point of the response input-output function using linear regression. Fourteen frequencies ranging from 5.6 to 152 kHz were studied. The results showed that most of the thresholds were lower than 90 dB re. 1 ?Pa (r.m.s.), covering a frequency range from 11.2 to 128 kHz, and the lowest threshold of 47 dB was measured at 45 kHz. The audiogram, which is a function of hearing threshold versus stimulus carrier frequency, presented a U-shape with a region of high hearing sensitivity (within 20 dB of the lowest threshold) between approximately 20 and 120 kHz. At frequencies lower than this high-sensitivity region, thresholds increased at a rate of approximately 11 dB octave(-1) up to 93 dB at 5.6 kHz. The thresholds at high frequencies above 108 kHz increased steeply at a rate of 130 dB octave(-1) up to 127 dB at 152 kHz. PMID:22660775

  14. The impact of synaptic conductance on action potential waveform: evoking realistic action potentials with a simulated synaptic conductance.

    PubMed

    Johnston, Jamie; Postlethwaite, Michael; Forsythe, Ian D

    2009-10-15

    Most current clamp studies trigger action potentials (APs) by step current injection through the recording electrode and assume that the resulting APs are essentially identical to those triggered by orthodromic synaptic inputs. However this assumption is not always valid, particularly when the synaptic conductance is of large magnitude and of close proximity to the axon initial segment. We addressed this question of similarity using the Calyx of Held/MNTB synapse; we compared APs evoked by long duration step current injections, short step current injections and orthodromic synaptic stimuli. Neither injected current protocol evoked APs that matched the evoked orthodromic AP waveform, showing differences in AP height, half-width and after-hyperpolarization. We postulated that this 'error' could arise from changes in the instantaneous conductance during the combined synaptic and AP waveforms, since the driving forces for the respective ionic currents are integrating and continually evolving over this time-course. We demonstrate that a simple Ohm's law manipulation of the EPSC waveform, which accounts for the evolving driving force on the synaptic conductance during the AP, produces waveforms that closely mimic those generated by physiological synaptic stimulation. This stimulation paradigm allows supra-threshold physiological stimulation (single stimuli or trains) without the variability caused by quantal fluctuation in transmitter release, and can be implemented without a specialised dynamic clamp system. Combined with pharmacological tools this method provides a reliable means to assess the physiological roles of postsynaptic ion channels without confounding affects from the presynaptic input. PMID:19560491

  15. [Recording cervical and ocular vestibular evoked myogenic potentials: part 1: anatomy, physiology, methods and normal findings].

    PubMed

    Walther, L E; Hörmann, K; Pfaar, O

    2010-10-01

    Vestibular evoked myogenic potentials (VEMP) have gained in clinical significance in recent years, now forming an integral part of neurootological examinations to establish the functional status of the otolith organs. They are sensitive to low-frequency acoustic stimuli. When stimulated, receptors in the sacculus and utriculous are activated. By means of reflexive connections, myogenic potentials can be recorded when the relevant muscles are tonically activated. The vestibulocolic (sacculocollic) reflex travels from the otolith organs over the central circuitry to the ipsilateral sternocleidomastoid muscle. Myogenic potentials can be recorded by means of cervical VEMP (cVEMP). The vestibuloocular reflex crosses contralaterally to the extraocular eye muscle. Ocular VEMP (oVEMP) are recorded periocularly, preferably from the inferior oblique muscle. Various stimulation methods are used including air conduction and bone conduction. PMID:20927621

  16. Diminished n1 auditory evoked potentials to oddball stimuli in misophonia patients.

    PubMed

    Schröder, Arjan; van Diepen, Rosanne; Mazaheri, Ali; Petropoulos-Petalas, Diamantis; Soto de Amesti, Vicente; Vulink, Nienke; Denys, Damiaan

    2014-01-01

    Misophonia (hatred of sound) is a newly defined psychiatric condition in which ordinary human sounds, such as breathing and eating, trigger impulsive aggression. In the current study, we investigated if a dysfunction in the brain's early auditory processing system could be present in misophonia. We screened 20 patients with misophonia with the diagnostic criteria for misophonia, and 14 matched healthy controls without misophonia, and investigated any potential deficits in auditory processing of misophonia patients using auditory event-related potentials (ERPs) during an oddball task. Subjects watched a neutral silent movie while being presented a regular frequency of beep sounds in which oddball tones of 250 and 4000 Hz were randomly embedded in a stream of repeated 1000 Hz standard tones. We examined the P1, N1, and P2 components locked to the onset of the tones. For misophonia patients, the N1 peak evoked by the oddball tones had smaller mean peak amplitude than the control group. However, no significant differences were found in P1 and P2 components evoked by the oddball tones. There were no significant differences between the misophonia patients and their controls in any of the ERP components to the standard tones. The diminished N1 component to oddball tones in misophonia patients suggests an underlying neurobiological deficit in misophonia patients. This reduction might reflect a basic impairment in auditory processing in misophonia patients. PMID:24782731

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

    NASA Astrophysics Data System (ADS)

    Hill, Randy J.; Mann, David A.

    2005-04-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2014-02-01

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

  20. Diagnostic use of dermatomal somatosensory-evoked potentials in spinal disorders: Case series

    PubMed Central

    Dikmen, Pinar Yalinay; Oge, A. Emre

    2013-01-01

    Objective/Context Dermatomal somatosensory-evoked potentials (dSEPs) may be valuable for diagnostic purposes in selected cases with spinal disorders. Design Reports on cases with successful use of dSEPs. Findings Cases 1 and 2 had lesions causing multiple root involvement (upper to middle lumbar region in Case 1 and lower sacral region in Case 2). Cystic lesions in both cases seemed to compress more than one nerve root, and stimulation at the center of the involved dermatomes in dSEPs helped to reveal the functional abnormality. Cases 3 and 4 had lesions involving the spinal cord with or without nerve root impairment. In Case 3, an magnetic resonance imaging (MRI)-verified lesion seemed to occupy a considerable volume of the lower spinal cord, causing only very restricted clinical sensory and motor signs. In Case 4, a cervical MRI showed a small well-circumscribed intramedullary lesion at right C2 level. All neurophysiological investigations were normal in the latter two patients (motor, tibial, and median somatosensory-evoked potentials in Case 3, and electromyography in both) except for the dSEPs. Conclusions Objectifying the presence and degree of sensory involvement in spinal disorders may be helpful for establishing diagnoses and in therapeutic decision-making. Valuable information could be provided by dSEPs in selected patients with multiple root or spinal cord involvement. PMID:24089995

  1. Onset Latency of Motor Evoked Potentials in Motor Cortical Mapping with Neuronavigated Transcranial Magnetic Stimulation

    PubMed Central

    Kallioniemi, Elisa; Pitkänen, Minna; Säisänen, Laura; Julkunen, Petro

    2015-01-01

    Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP) amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stable parameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provide information about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from the MEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique of MEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthanded volunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by using MEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in the centre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. In conclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathways from those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tract connections at the subcortical level will need to be verified in future studies with patients. PMID:26535068

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

    PubMed Central

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

    2013-01-01

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

  3. Electromagnetic interference in intraoperative monitoring of motor evoked potentials and a wireless solution.

    PubMed

    Farajidavar, Aydin; Seifert, Jennifer L; Delgado, Mauricio R; Sparagana, Steven; Romero-Ortega, Mario I; Chiao, J-C

    2016-02-01

    Intraoperative neurophysiological monitoring (IONM) is utilized to minimize neurological morbidity during spine surgery. Transcranial motor evoked potentials (TcMEPs) are principal IONM signals in which the motor cortex of the subject is stimulated with electrical pulses and the evoked potentials are recorded from the muscles of interest. Currently available monitoring systems require the connection of 40-60 lengthy lead wires to the patient. These wires contribute to a crowded and cluttered surgical environment, and limit the maneuverability of the surgical team. In this work, it was demonstrated that the cumbersome wired system is vulnerable to electromagnetic interference (EMI) produced by operating room (OR) equipment. It was hypothesized that eliminating the lengthy recording wires can remove the EMI induced in the IONM signals. Hence, a wireless system to acquire TcMEPs was developed and validated through bench-top and animal experiments. Side-by-side TcMEPs acquisition from the wired and wireless systems in animal experiments under controlled conditions (absence of EMI from OR equipment) showed comparable magnitudes and waveforms, thus demonstrating the fidelity in the signal acquisition of the wireless solution. The robustness of the wireless system to minimize EMI was compared with a wired-system under identical conditions. Unlike the wired-system, the wireless system was not influenced by the electromagnetic waves from the C-Arm X-ray machine and temperature management system in the OR. PMID:26678325

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

    PubMed

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

    2016-02-01

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

  5. Training induced alterations of visual evoked potentials are not related to body temperature.

    PubMed

    Ozkaya, Y G; Agar, A; Hacioglu, G; Yargiçoglu, P; Abidin, I; Senturk, U K

    2003-07-01

    The purpose of this study was to investigate the effect of mild chronic exercise on visual evoked potentials (VEPs). Twenty male Wistar rats were randomly divided into two groups: Control (C) and Exercise (E) groups. Exercise was performed on a motor-driven treadmill for 8 weeks. After 5 min of exercise, plasma lactic acid levels were determined. At the end of the experimental period, VEPs were recorded from E group twice: Five min (E-5 min) and 24 h (E-24 h) after the last bout of exercise. During visual evoked potential (VEP) recordings body temperature of the animals was kept constant to eliminate the effect of temperature changes. No difference was found between the lactic acid levels of two groups. The mean latencies of VEPs from E-5 min were shortened compared with the control group. The mean latencies of VEP components in E-24 h were observed to have returned to the control levels. Peak to peak amplitudes of VEPs were found to be unaltered among all measurements. We concluded that immediately after exercise, VEPs latencies were shortened independently from body temperature via unknown mechanisms. The latencies of VEPs were returned to control values after 24 h. PMID:12868047

  6. Association Between Evoked Potentials and Balance Recovery in Subacute Hemiparetic Stroke Patients

    PubMed Central

    Lee, So Young; Han, Eun Young

    2015-01-01

    Objective To investigate the association between baseline motor evoked potential (MEP) and somatosensory evoked potential (SSEP) responses in the lower extremities and balance recovery in subacute hemiparetic stroke patients. Methods MEPs and SSEPs were evaluated in 20 subacute hemiparetic stroke patients before rehabilitation. Balance (static posturography and Berg Balance Scale [BBS]), motor function (Fugl-Meyer Assessment [FMA]) and the ability to perform activities of daily living (Modified Barthel Index [MBI]) were evaluated before rehabilitation and after four-weeks of rehabilitation. Posturography outcomes were weight distribution indices (WDI) expressed as surface area (WDI-Sa) and pressure (WDI-Pr), and stability indices expressed as surface area (SI-Sa) and length (SI-L). In addition, all parameters were evaluated during eyes open (EO) and eyes closed (EC) conditions. Results The MEP (+) group showed significant improvements in balance except WDI-Sa (EC), FMA, and MBI, while the MEP (-) group showed significant improvements in the BBS, FMA, and MBI after rehabilitation. The SSEP (+) group showed significant improvements in balance except SI-Sa (EO), FMA, and MBI, while the SSEPs (-) group showed significant improvements in the BBS, MBI after rehabilitation. The changes in the SI-Sa (EO), SI-L (EO), total MBI, and several detailed MBI subscales in the MEP (+) group after rehabilitation were significantly larger than those in the MEP (-) group. Conclusion Our findings suggest that initial assessments of MEPs and SSEPs might be beneficial when predicting balance recovery in subacute hemiparetic stroke patients. PMID:26161352

  7. Color vision in attention-deficit/hyperactivity disorder: A pilot visual evoked potential study

    PubMed Central

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary

    2014-01-01

    Background Individuals with attention-deficit/hyperactivity disorder (ADHD) are reported to manifest visual problems (including ophthalmological and color perception, particularly for blue–yellow stimuli), but findings are inconsistent. Accordingly, this study investigated visual function and color perception in adolescents with ADHD using color Visual Evoked Potentials (cVEP), which provides an objective measure of color perception. Method Thirty-one adolescents (aged 13–18), 16 with a confirmed diagnosis of ADHD, and 15 healthy peers, matched for age, gender, and IQ participated in the study. All underwent an ophthalmological exam, as well as electrophysiological testing color Visual Evoked Potentials (cVEP), which measured the latency and amplitude of the neural P1 response to chromatic (blue–yellow, red–green) and achromatic stimuli. Result No intergroup differences were found in the ophthalmological exam. However, significantly larger P1 amplitude was found for blue and yellow stimuli, but not red/green or achromatic stimuli, in the ADHD group (particularly in the medicated group) compared to controls. Conclusion Larger amplitude in the P1 component for blue–yellow in the ADHD group compared to controls may account for the lack of difference in color perception tasks. We speculate that the larger amplitude for blue–yellow stimuli in early sensory processing (P1) might reflect a compensatory strategy for underlying problems including compromised retinal input of s-cones due to hypo-dopaminergic tone. PMID:25435188

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2001-01-01

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

  10. A postsleep decline in auditory evoked potential amplitude reflects sleep homoeostasis

    PubMed Central

    Hulse, Brad K.; Landsness, Eric C.; Sarasso, Simone; Ferrarelli, Fabio; Guokas, Jeffrey J.; Wanger, Tim; Tononi, Giulio

    2011-01-01

    Objective It has been hypothesized that slow wave activity, a well established measure of sleep homeostasis that increases after waking and decreases after sleep, may reflect changes in cortical synaptic strength. If so, the amplitude of sensory evoked responses should also vary as a function of time awake and asleep in a way that reflects sleep homeostasis. Methods Using 256-channel, high-density electroencephalography (EEG) in 12 subjects, auditory evoked potentials (AEP) and spontaneous waking data were collected during wakefulness before and after sleep. Results The amplitudes of the N1 and P2 waves of the AEP were reduced after a night of sleep. In addition, the decline in N1 amplitude correlated with low-frequency EEG power during non-rapid eye movement sleep and spontaneous wakefulness, both homeostatically regulated measures of sleep need. Conclusion The decline in AEP amplitude after a night of sleep may reflect a homeostatic reduction in synaptic strength. Significance These findings provide further evidence for a connection between synaptic plasticity and sleep homeostasis. PMID:21420904

  11. Improving the acquisition of nociceptive evoked potentials without causing more pain.

    PubMed

    Kramer, John L K; Haefeli, Jenny; Jutzeler, Catherine R; Steeves, John D; Curt, Armin

    2013-02-01

    Following nociceptive heat or laser stimulation, an early contralateral and later vertex potential can be recorded. Although more indicative of the nociceptive input, the acquisition of the contralateral N1 after contact heat stimulation (contact heat-evoked potentials [CHEPs]) remains difficult. An advantage of contact heat is that the baseline skin temperature preceding peak stimulation can be controlled. Increasing the baseline temperature may represent a novel strategy to improve the acquisition of CHEPs without resulting in more subjective pain to stimulation. A study was undertaken in 23 healthy subjects to examine the effects of increasing the baseline temperature but not the perceived intensity of contact heat stimulation. A combined standard averaging and single-trial analysis was performed to disclose how changes in averaged waveforms related to latency jitter and individual trial amplitudes. By increasing the baseline temperature, the acquisition of N1 was improved among subjects with a low-amplitude response (greater than -4?V) following 35C baseline temperature stimulation (P<.05). Based on standard averaging, N2/P2 amplitudes were also significantly increased with and without an accompanying change in the rating of perceived pain when the baseline temperature was increased (P<.05). In contrast, automated single-trial averaging revealed no significant difference in N2 amplitude when the baseline temperature was increased to 42C and the peak temperature reduced. These findings suggest that 2 mechanisms underlie the improved acquisition of CHEPs: increased synchronization of afferent volley, yielding larger-amplitude evoked potentials in response to the same rating of intensity; and reduced inter-trial variability. PMID:23218174

  12. Neuromodulation of motor-evoked potentials during stepping in spinal rats

    PubMed Central

    Gad, Parag; Lavrov, Igor; Shah, Prithvi; Zhong, Hui; Roy, Roland R.; Gerasimenko, Yury

    2013-01-01

    The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4–6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats. PMID:23761695

  13. Effect of selective attention on somatosensory evoked potentials in healthy people.

    PubMed

    Kozieł, H

    1985-01-01

    The effect of selective attention on various waves of the somatosensory evoked potentials was studied in healthy people in the area of specific projection (sensorimotor) and the area of non-specific projection (occipital). Significant changes of the amplitude of waves with latency exceeding 55 msec were observed when attention was concentrated on the received stimulus (I and II group of subjects). In group I the process of attention concentration was associated with a phenomenon connected with the new yet unknown experimental situation (prevalence of amplitude increase), while in group II habituation was observed (prevailing amplitude fall). Waves M125 and N200 in the sensorimotor area and N200 and N235-255 in the occipital area seemed to be associated in a peculiar way with the process of attention concentration. PMID:3837590

  14. Higher order statistics-based radial basis function network for evoked potentials.

    PubMed

    Lin, Bor-Shyh; Lin, Bor-Shing; Chong, Fok-Ching; Lai, Feipei

    2009-01-01

    In this study, higher order statistics-based radial basis function network (RBF) was proposed for evoked potentials (EPs). EPs provide useful information on diagnosis of the nervous system. They are time-varying signals typically buried in ongoing EEG, and have to be extracted by special methods. RBF with least mean square (LMS) algorithm is an effective method to extract EPs. However, using LMS algorithm usually encounters gradient noise amplification problem, i.e., its performance is sensitive to the selection of step sizes and additional noise. Higher order statistics technique, which can effectively suppress Gaussian and symmetrically distributed non-Gaussian noises, was used to reduce gradient noise amplification problem on adaptation in this study. Simulations and human experiments were also carried out in this study. PMID:19224723

  15. The N2-P3 complex of the evoked potential and human performance

    NASA Technical Reports Server (NTRS)

    Odonnell, Brian F.; Cohen, Ronald A.

    1988-01-01

    The N2-P3 complex and other endogenous components of human evoked potential provide a set of tools for the investigation of human perceptual and cognitive processes. These multidimensional measures of central nervous system bioelectrical activity respond to a variety of environmental and internal factors which have been experimentally characterized. Their application to the analysis of human performance in naturalistic task environments is just beginning. Converging evidence suggests that the N2-P3 complex reflects processes of stimulus evaluation, perceptual resource allocation, and decision making that proceed in parallel, rather than in series, with response generation. Utilization of these EP components may provide insights into the central nervous system mechanisms modulating task performance unavailable from behavioral measures alone. The sensitivity of the N2-P3 complex to neuropathology, psychopathology, and pharmacological manipulation suggests that these components might provide sensitive markers for the effects of environmental stressors on the human central nervous system.

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

    PubMed

    Samii, A; Wassermann, E M; Hallett, M

    1997-10-01

    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 the duration of isometric wrist extension, at 50% of maximum voluntary contraction, until the muscle fatigued. Fatigue was defined as the inability to maintain that force. The mean exercise duration before the muscle fatigued was 130 s, and post-exercise depression occurred only beyond 90 s of exercise. We conclude that post-exercise depression is detectable only after prolonged muscle activation. PMID:9362999

  17. Laser-evoked potentials as a tool for assessing the efficacy of antinociceptive drugs

    PubMed Central

    Truini, A.; Panuccio, G.; Galeotti, F.; Maluccio, M.R.; Sartucci, F.; Avoli, M.; Cruccu, G.

    2016-01-01

    Laser-evoked potentials (LEPs) are brain responses to laser radiant heat pulses and reflect the activation of Aδ nociceptors. LEPs are to date the reference standard technique for studying nociceptive pathway function in patients with neuropathic pain. To find out whether LEPs also provide a useful neurophysiological tool for assessing antinociceptive drug efficacy, in this double-blind placebo-controlled study we measured changes induced by the analgesic tramadol on LEPs in 12 healthy subjects. We found that tramadol decreased the amplitude of LEPs, whereas placebo left LEPs unchanged. The opioid antagonist naloxone partially reversed the tramadol-induced LEP amplitude decrease. We conclude that LEPs may be reliably used in clinical practice and research for assessing the efficacy of antinociceptive drugs. PMID:19477145

  18. Central-tendency estimation and nearest-estimate classification of multi-channel evoked potentials.

    PubMed

    Kota, Srinivas; Yarlagadda, Phani; Gupta, Lalit; Molfese, D L

    2009-01-01

    By modeling evoked potentials (EPs) as random vectors in which the EP samples are random variables, a generalized strategy is introduced to determine multivariate central-tendency estimates such as the arithmetic mean, geometric mean, harmonic mean, median, tri-mean, and trimmed-mean. Additionally, a generalized strategy is introduced to develop minimum-distance classifiers based on central tendency estimates. Furthermore, procedures are developed to fuse the decisions of the nearest-estimate classifiers for multi-channel EP classification. The central-tendency estimates of real EPs are compared and it is shown that although the mathematical operations to compute the estimates are quite different, the EP estimates are similar with respect to their overall waveform shapes and latencies. It is also shown that by fusing the classifier decisions across multiple channels, the classification accuracy can be improved significantly when compared with the accuracies of individual channel classifiers. PMID:19965215

  19. Addition of visual noise boosts evoked potential-based brain-computer interface.

    PubMed

    Xie, Jun; Xu, Guanghua; Wang, Jing; Zhang, Sicong; Zhang, Feng; Li, Yeping; Han, Chengcheng; Li, Lili

    2014-01-01

    Although noise has a proven beneficial role in brain functions, there have not been any attempts on the dedication of stochastic resonance effect in neural engineering applications, especially in researches of brain-computer interfaces (BCIs). In our study, a steady-state motion visual evoked potential (SSMVEP)-based BCI with periodic visual stimulation plus moderate spatiotemporal noise can achieve better offline and online performance due to enhancement of periodic components in brain responses, which was accompanied by suppression of high harmonics. Offline results behaved with a bell-shaped resonance-like functionality and 7-36% online performance improvements can be achieved when identical visual noise was adopted for different stimulation frequencies. Using neural encoding modeling, these phenomena can be explained as noise-induced input-output synchronization in human sensory systems which commonly possess a low-pass property. Our work demonstrated that noise could boost BCIs in addressing human needs. PMID:24828128

  20. A comparative study of recording procedures for motor evoked potential signals.

    PubMed

    Agrawal, Gracee; Iyer, Shrivats; All, Angelo H

    2009-01-01

    Motor evoked potential (MEP) signals serve as an objective measure of the functional integrity of motor pathways in the spinal cord. Hence, they provide a reliable assessment of the extent of spinal cord injury (SCI). There are two methods currently being used for serial MEP recordings in rats: a low-frequency and a high-frequency method. In this paper, we compared the two methods and determined the better method for MEP recordings. We also compared the effect of two anesthetic agents - inhalational isoflurane and intraperitoneal ketamine - on the MEP signals. We found that under ketamine anesthesia, low-frequency stimulation led to more consistent results, while high-frequency stimulation required greater stimulation intensity and was prone to unwanted side-effects including excessive head twitches. We further found that isoflurane anesthesia severely depressed the MEP response for both low-frequency and high-frequency stimulation which rendered the resulting signal unusable. PMID:19964577

  1. Evoked potential versus behavior to detect minor insult to the spinal cord in a rat model.

    PubMed

    Agrawal, Gracee; Thakor, Nitish V; All, Angelo H

    2009-08-01

    Reliable outcome measurement is needed for spinal cord injury research to critically evaluate the severity of injury and recovery thereafter. However, such measurements can sometimes be affected by minor, injury to the spinal cord during surgical procedures, including laminectomy. The open-field Basso, Beattie and Bresnahan (BBB) behavior motor scores are subjective and prone to human error. We investigated somatosensory evoked potential (SEP) as an electrophysiological measure to assess the integrity of the spinal cord after injury. In our experiment, control rats with a minor unintentional spinal cord insult during laminectomy showed a decrease in SEP amplitude by 16% to 18%, which recovered in around 7 days. However, there was no change in the BBB scores for the same animals over the same period. This highlights the sensitivity of SEP to minor insult as compared to BBB. These differences may be beneficial in accurate evaluation of the severity and progression of spinal cord injury, and subsequent recovery. PMID:19419872

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

    PubMed Central

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

    1985-01-01

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

  3. [Extraction of evoked related potentials by using the combination of independent component analysis and wavelet analysis].

    PubMed

    Zou, Ling; Chen, Shuyue; Sun, Yuqiang; Ma, Zhenghua

    2010-08-01

    In this paper we present a new method of combining Independent Component Analysis (ICA) and Wavelet de-noising algorithm to extract Evoked Related Potentials (ERPs). First, the extended Infomax-ICA algorithm is used to analyze EEG signals and obtain the independent components (Ics); Then, the Wave Shrink (WS) method is applied to the demixed Ics as an intermediate step; the EEG data were rebuilt by using the inverse ICA based on the new Ics; the ERPs were extracted by using de-noised EEG data after being averaged several trials. The experimental results showed that the combined method and ICA method could remove eye artifacts and muscle artifacts mixed in the ERPs, while the combined method could retain the brain neural activity mixed in the noise Ics and could extract the weak ERPs efficiently from strong background artifacts. PMID:20842836

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

    PubMed

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

    2015-08-01

    Visual prostheses are becoming a reality as a therapy to restore functional vision to the blind. New stimulation strategies and novel electrode designs are contributing to accelerate the development of such devices triggering the interest of scientists, clinicians and the blind community worldwide. In this scenario, there is a need for large animal models that are suitable for preclinical testing of retinal neuroprostheses. This study presents an electrophysiology assessment of an ovine model for single and simultaneous electrode stimulation from the suprachoroidal space, using symmetric biphasic current pulses with a monopolar return configuration. Visually and electrically evoked potentials were recorded using supradural surface electrodes, showing charge thresholds comparable to those in humans. This model represents an alternative to feline or canine models with analogous activation levels and an eye anatomy similar to that of humans. PMID:26737012

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

    PubMed

    Ito, Yosuke; Maehara, Seiya; Itoh, Yoshiki; Matsui, Ai; Hayashi, Miri; Kubo, Akira; Uchide, Tsuyoshi

    2016-04-01

    The purpose of this study was to investigate the effects of refractive error on canine visual evoked potentials with pattern stimulation (P-VEP). Six normal beagle dogs were used. The refractive power of the recorded eyes was measured by skiascopy. The refractive power was corrected to -4 diopters (D) to +2 D using contact lens. P-VEP was recorded at each refractive power. The stimulus pattern size and distance were 50.3 arc-min and 50 cm. The P100 appeared at almost 100 msec at -2 D (at which the stimulus monitor was in focus). There was significant prolongation of the P100 implicit time at -4, -3, 0 and +1 D compared with -2 D, respectively. We concluded that the refractive power of the eye affected the P100 implicit time in canine P-VEP recording. PMID:26655769

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

    PubMed Central

    2014-01-01

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

  7. Possible Long Term Effects of Chemical Warfare Using Visual Evoked Potentials

    PubMed Central

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

    2014-01-01

    Some studies have already addressed the effects of occupational organic solvent exposure on the visually evoked potentials (VEPs). Visual system is an important target for Sulphur Mustard (SM) toxicity. A number of Iranian victims of Sulphur Mustard (SM) agent were apprehensive about the delay effect of SM on their vision and a possible delay effect of SM on their visual cortex. This investigation was performed on 34 individuals with a history of chemical exposure and a control group of 15 normal people. The Toennies electro-diagnosis device was used and its signals were saved as the latencies. The mean of N75, N140 and P100 of victims of chemical warfare (VCWs) and control group indicated no significant results (P>0.05). The VCWs did not show any visual symptoms and there was no clear deficit in their VEPs. PMID:25242846

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

    PubMed

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

    2014-09-01

    Some studies have already addressed the effects of occupational organic solvent exposure on the visually evoked potentials (VEPs). Visual system is an important target for Sulphur Mustard (SM) toxicity. A number of Iranian victims of Sulphur Mustard (SM) agent were apprehensive about the delay effect of SM on their vision and a possible delay effect of SM on their visual cortex. This investigation was performed on 34 individuals with a history of chemical exposure and a control group of 15 normal people. The Toennies electro-diagnosis device was used and its signals were saved as the latencies. The mean of N75, N140 and P100 of victims of chemical warfare (VCWs) and control group indicated no significant results (P>0.05). The VCWs did not show any visual symptoms and there was no clear deficit in their VEPs. PMID:25242846

  9. Slow negative evoked potentials in the rhesus monkey (Macaca mulatta): myogenic versus neurogenic influences.

    PubMed

    Fria, T J; Saad, M M; Doyle, W J; Cantekin, E I

    1984-02-01

    The influence of myogenic activity on the generation of slow negative evoked potentials (SN10) to octave, toneburst stimuli (0.5-2 Hz) was investigated in 5 rhesus monkeys (M. mulatta) by comparing responses obtained prior to and during total paralysis induced with curare. The SN10 could be easily elicited during paralysis, regardless of stimulus intensity, rate, or frequency. During paralysis, there were no systematic changes in either response latency or amplitude; variability in latency was less than 10% and changes in response amplitude were within 30%. These findings suggest that the myogenic contribution to the SN10 response is negligible and that this response is of neurogenic origin in the rhesus monkey. PMID:6198169

  10. Targeting Pain-evoking Transient Receptor Potential Channels for the Treatment of Pain

    PubMed Central

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

    2013-01-01

    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

  11. Normal Amplitude of Electroretinography and Visual Evoked Potential Responses in AβPP/PS1 Mice.

    PubMed

    Leinonen, Henri; Lipponen, Arto; Gurevicius, Kestutis; Tanila, Heikki

    2016-01-19

    Alzheimer's disease has been shown to affect vision in human patients and animal models. This may pose the risk of bias in behavior studies and therefore requires comprehensive investigation. We recorded electroretinography (ERG) under isoflurane anesthesia and visual evoked potentials (VEP) in awake amyloid expressing AβPPswe/PS1dE9 (AβPP/PS1) and wild-type littermate mice at a symptomatic age. The VEPs in response to patterned stimuli were normal in AβPP/PS1 mice. They also showed normal ERG amplitude but slightly shortened ERG latency in dark-adapted conditions. Our results indicate subtle changes in visual processing in aged male AβPP/PS1 mice specifically at a retinal level. PMID:26836173

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

    PubMed Central

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

    2015-01-01

    The purpose of this study was to investigate the effects of refractive error on canine visual evoked potentials with pattern stimulation (P-VEP). Six normal beagle dogs were used. The refractive power of the recorded eyes was measured by skiascopy. The refractive power was corrected to −4 diopters (D) to +2 D using contact lens. P-VEP was recorded at each refractive power. The stimulus pattern size and distance were 50.3 arc-min and 50 cm. The P100 appeared at almost 100 msec at −2 D (at which the stimulus monitor was in focus). There was significant prolongation of the P100 implicit time at −4, −3, 0 and +1 D compared with −2 D, respectively. We concluded that the refractive power of the eye affected the P100 implicit time in canine P-VEP recording. PMID:26655769

  13. Comparison of acuity tests and pattern evoked potential criteria: two mechanisms underly acuity maturation in man.

    PubMed

    Spekreijse, H

    1983-10-01

    A comparative study of acuity tests and pattern evoked potential (EP) criteria was performed on a total of 307 subjects, 214 of them at an age between 2 months post-term and 12 years. All were examined ophthalmologically prior to testing. It was shown that both psychophysical and EP estimated acuity improve in the same way until puberty. From birth to about 6 months a rapid improvement is found. This fast phase can probably be attributed to retinal morphological maturation. During this period a fair estimate of acuity can be obtained by determining the checksize that yields the largest EP; a conclusion of practical importance for screening. The subsequent slow improvement phase, which ends around puberty, is reflected in the development of the waveform of the pattern onset EP. Since it correlates with the growth of a spatial contrast specific component of extrastriate origin in the EP, the slow improvement phase most likely reflects maturation of central processes. PMID:6639719

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

    PubMed Central

    Chan, Pei-Ying S.; Cheng, Chia-Hsiung; Hsu, Shih-Chieh; Liu, Chia-Yih; Davenport, Paul W.; von Leupoldt, Andreas

    2015-01-01

    The perception of respiratory sensations plays an important role both in respiratory diseases and in anxiety disorders. However, little is known about the neural processes underlying respiratory sensory perception, especially in patient groups. Therefore, the present study examined whether patients with generalized anxiety disorder (GAD) would demonstrate altered respiratory sensory gating compared to a healthy control group. Respiratory-related evoked potentials (RREP) were measured in a paired inspiratory occlusion paradigm presenting two brief occlusion stimuli (S1 and S2) within one inspiration. The results showed a significantly greater S2/S1 ratio for the N1 component of the RREP in the GAD group compared to the control group. Our findings suggest altered respiratory sensory processing in patients with GAD, which might contribute to altered perception of respiratory sensations in these patients. PMID:26217278

  15. The pontomesencephalic tegmentum delays the peak latency of the visual evoked potential in rats.

    PubMed

    Bringmann, A

    1995-12-29

    In previous experiments it was found that physostigmine application in unrestrained rats delayed the peak latency of the visual evoked potential (VEP). The present study was carried out to find the putative site that cholinergically mediates the latency delay of rat's VEP. After unilateral ibotenic acid lesions of the nucleus basalis magnocellularis (NBM) and the pedunculopontine tegmental nucleus (PPTg), respectively, the VEPs of freely moving rats were recorded in different behavioural states. While NBM lesion did not alter the behavioural modulation of the VEP latency, the PPTg lesion produced shorter VEP latencies in the occipital cortex of the lesioned hemisphere in high and moderate arousal states. The peak latency shortening was significant for exploratory sniffing. Physostigmine but not nicotine application abolished the shorter VEP latency. The results indicate a muscarinic mechanism within the pontomesencephalic tegmentum that ipsilaterally delayed the VEP latency in high and moderate but not in low arousal states. PMID:8787819

  16. Signal statistics in objective auditory evoked potential (AEP) detection by the phase spectral method.

    PubMed

    Ross, A J; Beagley, H A; Sayers, B M

    1980-10-01

    This paper reports on statistical aspects relevant to the use of the phase spectrum of post-stimulus EEG, in objective detection of the auditory evoked potential. The sampling statistics of two statistical estimators are discussed: the mean phase vector magnitude, and the standard deviation of an ensemble of post-stimulus EEG phases. These two estimators are circular statistics, and subject to strong sample size bias. Their confidence intervals have been derived empirically for sample sizes routinely used in clinical audiometry. A trial example illustrates the use of the objective phase statistics developed here; it is noted that the method may also be more efficient than the visual scoring of averaged responses. PMID:7464085

  17. Abnormal visual-evoked potentials in leukemic children after cranial radiation

    SciTech Connect

    Russo, A.; Tomarchio, S.; Pero, G.; Consoli, G.; Marina, R.; Rizzari, C.; Schiliro, G.

    1985-01-01

    Visual-evoked potentials (VEPs) were studied in 55 asymptomatic children with leukemia or solid tumors in remission in order to detect subclinical demyelination of the optic pathway after CNS prophylaxis. In group I (11 patients with ALL studied prospectively), VEP latency was increased in ten after cranial radiation (CR) as compared with previous values. Group II (18 patients with ALL in maintenance) and group III (16 patients with ALL off therapy) were studied retrospectively and VEP latency was found above normal limits in 33 and 31%, respectively. In group IV (four patients with solid tumors and six with leukemia, all of whom received no CR), VEP latency was normal despite periodical intrathecal methotrexate administrations to five of them. The authors conclude that CR determines a slowing of conduction on VEP test, probably due to demyelination of the optic pathway, in a high proportion of patients. The future clinical significance of these findings must be established throughout a prolonged follow-up period.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2005-01-01

    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 motor imagery of a maximal handgrip contraction, in eight neurologically normal subjects, before and after a 2-min maximal voluntary handgrip contraction. Resting MEP amplitude was facilitated by motor imagery in three of the four muscles, but consistently only in two. Motor imagery also reduced the trial-to-trial variability of resting MEPs. Following the exercise, resting MEP amplitude was depressed reliably in only one muscle engaged in the task, although two other muscles exhibited some depression. Motor imagery MEPs were smaller after exercise, but the degree of facilitation compared to the rest MEP was unchanged. In experiment 2, TMS intensity was increased after exercise-induced MEP depression so that the MEP amplitude matched the pre-exercise baseline. The amplitude of the MEP facilitated with motor imagery was not altered by MEP depression, nor was it increased when the TMS intensity was increased. These results suggest, at least with a simple motor task, that while post-exercise depression reduces corticospinal excitability, it does not appear to significantly affect the strength of the input to the motor cortex from those areas of the brain responsible for the storage and generation of internal representations of movement. PMID:15502993

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

    PubMed

    Matsumoto, Riki; Kunieda, Takeharu; Ikeda, Akio

    2012-09-01

    A better understanding of seizure networks and the mechanisms underlying human higher cortical functions requires a detailed knowledge of neuronal connectivity. As it relates to higher cortical functions, such as language, in humans, studies performed in nonhuman primates are less relevant. By using subdural electrodes implanted for presurgical evaluation, we developed an in vivo electrical tract-tracing technique of cortico-cortical evoked potentials (CCEPs). Cortico-cortical connections could be traced by applying repetitive single-pulse electrical stimuli to a part of the cortices and recording evoked cortical potentials from adjacent and remote cortical regions by averaging electrocorticogram time-locked to stimulus onset. This technique has contributed to the understanding of human cortico-cortical networks involved in higher brain functions, such as language, praxis, and higher motor control. Establishing a CCEP connectivity map in the MNI standard space is also of academic importance, since a standardized CCEP connectivity map would provide a substantial reference for noninvasive network analyses. In addition to its importance in basic systems neuroscience, this method, in combination with conventional cortical mapping, could be used to clinically map functional brain systems by tracking cortico-cortical connections among functional cortical regions in individual patients. This approach may help identify the cortico-cortical network of a given function within the context of pathology and any resultant plasticity of brain systems. In relation to epileptogenicity, as CCEPs can be used as a measure of regional cortical excitability, stimulating the epileptic focus and recording CCEPs in adjacent areas could help evaluate cortical excitability at and around the focus. PMID:22941836

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2016-01-01

    Purpose: Traditionally, the topography of somatosensory evoked potentials (SEPs) is generated based on amplitude and latency. However, this operation focuses on the physical morphology and field potential-power, so it suffers from difficulties in performing identification in an objective manner. In this study, measurement of the synchronization of SEPs is proposed as a method to explore brain functional networks as well as the plasticity after peripheral nerve injury. Method: SEPs elicited by unilateral sciatic nerve stimulation in twelve adult male Sprague-Dawley (SD) rats in the normal group were compared with SEPs evoked after unilateral sciatic nerve hemisection in four peripheral nerve injured SD rats. The characterization of synchronized networks from SEPs was conducted using equal-time correlation, correlation matrix analysis, and comparison to randomized surrogate data. Eigenvalues of the correlation matrix were used to identify the clusters of functionally synchronized neuronal activity, and the participation index (PI) was calculated to indicate the involvement of each channel in the cluster. The PI value at the knee point of the PI histogram was used as a threshold to demarcate the cortical boundary. Results: Ten out of the twelve normal rats showed only one synchronized brain network. The remaining two normal rats showed one strong and one weak network. In the peripheral nerve injured group, only one synchronized brain network was found in each rat. In the normal group, all network shapes appear regular and the network is largely contained in the posterior cortex. In the injured group, the network shapes appear irregular, the network extends anteriorly and posteriorly, and the network area is significantly larger. There are considerable individual variations in the shape and location of the network after peripheral nerve injury. Conclusion: The proposed method can detect functional brain networks. Compared to the results of the traditional SEP-morphology-based analysis method, the synchronized functional network area is much larger. Furthermore, the proposed method can also characterize the rapid cortical plasticity after a peripheral nerve is acutely injured. PMID:27199728

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

    PubMed Central

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

    2015-01-01

    Background Tinnitus is an important occupational health concern, but few studies have focused on the central auditory pathways of workers with a history of occupational noise exposure. Thus, we analyzed the central auditory pathways of workers with a history of occupational noise exposure who had normal hearing threshold, and compared middle latency auditory evoked potential in those with and without noise-induced tinnitus. Material/Methods Sixty individuals (30 with and 30 without tinnitus) underwent the following procedures: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25–8 kHz, and middle latency auditory evoked potentials. Results Quantitative analysis of latencies and amplitudes of middle latency auditory evoked potential showed no significant differences between the groups with and without tinnitus. In the qualitative analysis, we found that both groups showed increased middle latency auditory evoked potential latencies. The study group had more alterations of the “both” type regarding the Na-Pa amplitude, while the control group had more “electrode effect” alterations, but these alterations were not significantly different when compared to controls. Conclusions Individuals with normal hearing with or without tinnitus who are exposed to occupational noise have altered middle latency auditory evoked potential, suggesting impairment of the auditory pathways in cortical and subcortical regions. Although differences did not reach significance, individuals with tinnitus seemed to have more abnormalities in components of the middle latency auditory evoked potential when compared to individuals without tinnitus, suggesting alterations in the generation and transmission of neuroelectrical impulses along the auditory pathway. PMID:26358094

  5. Usefulness of the Combined Motor Evoked and Somatosensory Evoked Potentials for the Predictive Index of Functional Recovery After Primary Pontine Hemorrhage

    PubMed Central

    Seong, Jin Wan; Kim, Min Ho; Shin, Hyo Keong; Lee, Han Do; Park, Jun Bum

    2014-01-01

    Objective To investigate the predictive index of functional recovery after primary pontine hemorrhage (PPH) using the combined motor evoked potential (MEP) and somatosensory evoked potential (SEP) in comparison to the hematoma volume and transverse diameter measured with computerized tomography. Methods Patients (n=14) with PPH were divided into good- and poor-outcome groups according to the modified Rankin Score (mRS). We evaluated clinical manifestations, radiological characteristics, and the combined MEP and SEP responses. The summed MEP and SEP (EP sum) was compared to the hematoma volume and transverse diameter predictive index of global disability, gait ability, and trunk stability in sitting posture. Results All measures of functional status and radiological parameters of the good-outcome group were significantly better than those of the poor-outcome group. The EP sum showed the highest value for the mRS and functional ambulatory category, and transverse diameter showed the highest value for "sitting-unsupported" of Berg Balance Scale. Conclusion The combined MEP and SEP is a reliable and useful tool for functional recovery after PPH. PMID:24639921

  6. Presynaptic Calcium Dynamics and Transmitter Release Evoked by Single Action Potentials at Mammalian Central Synapses

    PubMed Central

    Sinha, Saurabh R.; Wu, Ling-Gang; Saggau, Peter

    1997-01-01

    The relationship between presynaptic calcium transients ([Ca2+]t) and transmitter release evoked by a single stimulus was both investigated experimentally and modeled at a mammalian central synapse, the CA3 to CA1 pyramidal cell synapse in guinea pig hippocampal slices. In the present study, we compared the low-affinity calcium indicator furaptra with the higher-affinity indicator fura-2. The 10-90% rise time of the furaptra transient was 2.4 ms compared to 7.8 ms with fura-2; the half-decay time (τ1/2) was 30 ms for furaptra, compared to 238 ms for fura-2. The half-width of the calcium influx was 1.8 ms with furaptra, which provides an upper limit to the duration of the calcium current (ICa) evoked by an action potential. Modeling the decay time course of the furaptra transients led to the conclusion that the predominant endogenous calcium buffer in these terminals must have relatively slow kinetics (kon < 105/M·s), although the presence of small amounts of fast buffers cannot be excluded. The relationship between the [Ca2+]t measured with furaptra and the postsynaptic response was the same as previously observed with fura-2: the postsynaptic response was proportional to about the fourth power (m ≈ 4) of the amplitude of either [Ca2+]t or calcium influx. Thus, although fura-2 may be locally saturated by the high local [Ca2+] responsible for transmitter release, the volume-averaged fura-2 signal accurately reflects changes in this local concentration. The result that both indicators gave similar values for the power m constrains the amplitude of calcium influx in our model: ICa < 1 pA for 1 ms. ImagesFIGURE 1 PMID:9017193

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

    PubMed

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

    2015-12-01

    Vagus nerve stimulation (VNS) is a treatment for refractory epilepsy and depression. Previous studies using invasive recording electrodes showed that VNS induces laryngeal motor-evoked potentials (LMEPs) through the co-activation of the recurrent laryngeal nerve and subsequent contractions of the laryngeal muscles. The present study investigates the feasibility of recording LMEPs in chronically VNS-implanted rats, using a minimally-invasive technique, to assess effective current delivery to the nerve and to determine optimal VNS output currents for vagal fiber activation. Three weeks after VNS electrode implantation, signals were recorded using an electromyography (EMG) electrode in the proximity of the laryngeal muscles and a reference electrode on the skull. The VNS output current was gradually ramped up from 0.1 to 1.0 mA in 0.1 mA steps. In 13/27 rats, typical LMEPs were recorded at low VNS output currents (median 0.3 mA, IQR 0.2-0.3 mA). In 11/27 rats, significantly higher output currents were required to evoke electrophysiological responses (median 0.7 mA, IQR 0.5-0.7 mA, p < 0.001). The latencies of these responses deviated significantly from LMEPs (p < 0.05). In 3/27 rats, no electrophysiological responses to simulation were recorded. Minimally invasive LMEP recordings are feasible to assess effective current delivery to the vagus nerve. Furthermore, our results suggest that low output currents are sufficient to activate vagal fibers. PMID:26510476

  8. Electrocorticogram spectral analysis and somatosensory evoked potentials as tools to assess electrical stunning efficiency in ducks.

    PubMed

    Beyssen, C; Babile, R; Fernandez, X

    2004-06-01

    1. Fast Fourier transformations (FFTs) of electrocorticogram (ECoG) signals and averaging of somatosensory evoked potentials (SEPs) were used for assessing the impact of electrical stunning of ducks in a waterbath set to deliver a constant current of 150 mA, 600 Hz alternating current (AC) for 4 s. The effectiveness of stunning was determined on the basis of induction of epileptiform activity in the ECoG followed by a decrease in total power content to less than 10% of pre-stun values and abolition of SEPs. 2. One out of 10 birds was killed by the stun. FFT analysis of the ECoG signals of the remaining 9 birds showed that only one bird had a decrease of the total power to less than 10% of the pre-stun values for up to 70 s post-stun. The SEPs were retained in 6 out of 9 ducks and and 4 of them retained the evoked responses throughout the post-stun period. In the two birds showing abolition of SEPs, this was associated with a decrease in the total power content to below 10% of the pre-stun value. 3. The present experiment confirmed that the abolition of SEPs and the decrease of the total power below 10% of the pre-stun value for assessing unconsciousness after an electrical stunning in various species are also applicable to ducks. Based on this, it is concluded that electrical waterbath stunning of ducks using 150 mA of 600 Hz AC is ineffective. PMID:15327129

  9. Effect of higher frequency on the classification of steady-state visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Won, Dong-Ok; Hwang, Han-Jeong; Dähne, Sven; Müller, Klaus-Robert; Lee, Seong-Whan

    2016-02-01

    Objective. Most existing brain-computer interface (BCI) designs based on steady-state visual evoked potentials (SSVEPs) primarily use low frequency visual stimuli (e.g., <20 Hz) to elicit relatively high SSVEP amplitudes. While low frequency stimuli could evoke photosensitivity-based epileptic seizures, high frequency stimuli generally show less visual fatigue and no stimulus-related seizures. The fundamental objective of this study was to investigate the effect of stimulation frequency and duty-cycle on the usability of an SSVEP-based BCI system. Approach. We developed an SSVEP-based BCI speller using multiple LEDs flickering with low frequencies (6-14.9 Hz) with a duty-cycle of 50%, or higher frequencies (26-34.7 Hz) with duty-cycles of 50%, 60%, and 70%. The four different experimental conditions were tested with 26 subjects in order to investigate the impact of stimulation frequency and duty-cycle on performance and visual fatigue, and evaluated with a questionnaire survey. Resting state alpha powers were utilized to interpret our results from the neurophysiological point of view. Main results. The stimulation method employing higher frequencies not only showed less visual fatigue, but it also showed higher and more stable classification performance compared to that employing relatively lower frequencies. Different duty-cycles in the higher frequency stimulation conditions did not significantly affect visual fatigue, but a duty-cycle of 50% was a better choice with respect to performance. The performance of the higher frequency stimulation method was also less susceptible to resting state alpha powers, while that of the lower frequency stimulation method was negatively correlated with alpha powers. Significance. These results suggest that the use of higher frequency visual stimuli is more beneficial for performance improvement and stability as time passes when developing practical SSVEP-based BCI applications.

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

    ERIC Educational Resources Information Center

    Clarke, Elaine M; Adams, Catherine

    2007-01-01

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

  11. Visual evoked potentials in normal and sulfite oxidase deficient rats exposed to ingested sulfite.

    PubMed

    Küçükatay, Vural; Hacioğlu, Gülay; Savcioğlu, Feyza; Yargiçoğlu, Piraye; Ağar, Aysel

    2006-01-01

    Sulfite oxidase (SOX) is an essential enzyme in the pathway of the oxidative degradation of sulfur amino acids, and protects cells from sulfite (SO(3)(2-)) toxicity. Rats do not mimic responses seen in human, because of their relatively high SOX activity levels. Therefore, the present study used SOX deficient rats since they are a more appropriate model for studying sulfite toxicity. The aim of the study was to investigate the effect of sulfite exposure on visual evoked potentials (VEPs) and thiobarbituric acid reactive substances (TBARS) in normal and sulfite oxidase deficient rats. Rats were assigned to six groups (n=10 rats/group) as follows; control (C), sulfite (S), sulfite+vitamin E (SE), deficient (D), deficient+sulfite (DS) and deficient+sulfite+vitamin E (DSE). Sulfite oxidase deficiency was established by feeding rats a low molybdenum diet and adding to their drinking water 200 ppm tungsten (W). Sulfite (25img/kg) was administered to the animals via their drinking water. At the end of the experimental period, flash visual evoked potentials were recorded, and TBARS, hepatic sulfite oxidase levels and plasma S-sulphonate concentrations were determined. Sulfite treatment caused a significant delay in P1, N1P2, and P3 components of VEPs in the S and DS groups compared with the C group. These prolonged mean latencies of VEP components were reversed by vitamin E treatment in SE and DSE groups. In addition, the mean latencies of P1 and P3 components were increased in SOX deficient groups compared with the C group. Lipid peroxidation was increased in the brain in S, D, DS and DSE groups compared with the control group. There were also significant increases in the retina TBARS levels of S and DS groups. Vitamin E caused a significant decrease in brain and retina TBARS levels of SE and DSE groups with respect to their corresponding controls. However, there were no important changes in amplitudes of other groups. In conclusion, our results showed that sulfite treatment caused an increase in the lipid peroxidation process that was accompanied by changes in VEPs. Furthermore, sulfite exposure resulted in greater lipid peroxidation and more electrophysiological alterations in the SOX deficient rats than in the control rats. Additionally, the reduction of all VEP latencies in the DSE group with respect to the DS group clearly indicated that vitamin E has the potential to prevent sulfite induced-VEP changes arising from dysfunction of the SOX enzyme. PMID:16150492

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

    PubMed Central

    Singh, Nilkamal; Telles, Shirley

    2015-01-01

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

  13. Cortical evoked potentials from pallidal stimulation in patients with primary generalized dystonia.

    PubMed

    Tisch, Stephen; Rothwell, John C; Zrinzo, Ludvic; Bhatia, Kailash P; Hariz, Marwan; Limousin, Patricia

    2008-01-30

    Deep brain stimulation (DBS) of globus pallidus internus (GPi) has emerged as an effective treatment for primary generalized dystonia. However, the physiological mechanisms of improvement are not fully understood. Cortical activity in response to pallidal stimulation was recorded in 6 patients with primary generalized dystonia >6 months after bilateral GPi DBS. Scalp electroencephalogram was recorded using 60 surface electrodes during 10 Hz bipolar pallidal DBS at each electrode contact pair. Anatomical position of the electrode contacts in relation to the GPi, medial medullary lamina and globus pallidus externus (GPe) was determined from the postoperative stereotactic MRI. In all six patients an evoked potential (EP) was observed with average onset latency of 10.9 ms +/- 0.77, peak latency 26.6 ms +/- 1.6, distributed mainly over the ipsilateral hemisphere, maximal centrally. The mean amplitude of this potential was larger with stimulation in posteroventral GPi than in GPe (3.36 microV vs. 0.50 microV, P < 0.0001). The EP was absent in one patient-side, ipsilateral to a previous thalamotomy. Low frequency GPi stimulation produces an EP distributed centrally over the ipsilateral hemisphere. The latency and distribution of the EP are consistent with stimulation of pallidothalamic neurons projecting to the sensorimotor cortex. Because the EP is larger and more consistently present with stimulation of posteroventral GPi than GPe, it may provide a physiological tool to identify contacts within the optimal surgical target. PMID:18044698

  14. Cortical Auditory Evoked Potentials in Children with a Hearing Loss: A Pilot Study

    PubMed Central

    Koravand, Amineh; Jutras, Benoît; Lassonde, Maryse

    2012-01-01

    Objective. This study examined the patterns of neural activity in the central auditory system in children with hearing loss. Methods. Cortical potentials and mismatch responses (MMRs) were recorded from ten children aged between 9 and 10 years: five with hearing loss and five with normal hearing in passive oddball paradigms using verbal and nonverbal stimuli. Results. Results indicate a trend toward larger P1 amplitude, a significant reduction in amplitude, and latency of N2 in children with hearing loss compared to control. No significant group differences were observed for the majority of the MMRs conditions. Conclusions. Data suggest that the reduced auditory input affects the pattern of cortical-auditory-evoked potentials in children with a mild to moderately severe hearing loss. Results suggest maturational delays and/or deficits in central auditory processing in children with hearing loss, as indicated by the neurophysiological markers P1 and N2. In contrast, negative MMR data suggest that the amplification provided by the hearing aids could have allowed children with hearing loss to develop adequate discriminative abilities. PMID:22291717

  15. Effect of intrathecal bupivacaine on somatosensory evoked potentials following dermatomal stimulation.

    PubMed

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

    1987-09-01

    The effect of spinal anesthesia with 3.6 +/- 0.1 ml (mean +/- SEM) of 0.5% bupivacaine on early (less than 150 msec) somatosensory evoked potentials (SEPs) with electrical stimulation of the L1 and S1 dermatomes was examined in 12 patients. The mean level of sensory analgesia (pinprick) was T8,9 +/- 1.0 (+/- SEM) and the mean degree of motor blockade was 1.3 +/- 0.1 (Bromage scale). Intrathecal bupivacaine significantly (P less than 0.05) decreased the amplitude of all SEP components after stimulation of the L1 dermatome and most components during stimulation of the S1 dermatome. Intrathecal bupivacaine also increased the latency of SEPs (P less than 0.05) of both dermatomes. The L1 SEP disappeared in 7 and the S1 SEPs in 5 of the 12 patients during neural blockade. In three patients the SEPs disappeared at both locations. Sensory thresholds increased significantly during blockade. We found no correlation between decrease of amplitude and degree of motor blockade or level of sensory analgesia. Thus, intrathecal plain bupivacaine has a strong depressant effect on the neural afferent transmission as assessed by SEPs. However, despite clinically effective blockade as assessed by pinprick and motor blockade nerve potentials after nociceptive stimulation within the area of sensory block were often able to pass to the cerebral cortex. PMID:3039873

  16. Effect of isoflurane on somatosensory evoked potentials in a rat model.

    PubMed

    Kortelainen, Jukka; Vipin, Ashwati; Thow Xin Yuan; Mir, Hasan; Thakor, Nitish; Al-Nashash, Hasan; All, Angelo

    2014-01-01

    Somatosensory evoked potentials (SEPs) are widely used in the clinic as well as research to study the functional integrity of the different parts of sensory pathways. However, most general anesthetics, such as isoflurane, are known to suppress SEPs, which might affect the interpretation of the signals. In animal studies, the usage of anesthetics during SEP measurements is inevitable due to which detailed effect of these drugs on the recordings should be known. In this paper, the effect of isoflurane on SEPs was studied in a rat model. Both time and frequency properties of the cortical recordings generated by stimulating the tibial nerve of rat's hindlimb were investigated at three different isoflurane levels. While the anesthetic agent is shown to generally suppress the amplitude of the SEP, the effect was found to be nonlinear influencing more substantially the latter part of waveform. This finding will potentially help us in future work aiming at separating the effects of anesthetics on SEP from those due to injury in the ascending neural pathways. PMID:25570940

  17. Topical capsaicin selectively attenuates heat pain and A delta fiber-mediated laser-evoked potentials.

    PubMed

    Beydoun, A; Dyke, D B; Morrow, T J; Casey, K L

    1996-01-01

    Cutaneous stimulation with CO2 laser pulses activates A delta of nociceptive afferents and evokes late cerebral potentials (LEPs), the amplitude of which correlates parametrically with the perceived magnitude estimation of laser pulses. Capsaicin is known to desensitize the nociceptive terminals of C fibers. In this double-blind, vehicle-controlled experiment, we tested the hypothesis that topical capsaicin would inactivate A delta afferents and lead to an attenuation of the LEPs. Subjects applied capsaicin cream to the dorsum of one hand and vehicle cream to the other 3 times daily for a period of 5 weeks. At weekly intervals before starting, during administration and after discontinuation of capsaicin, LEPs were recorded and psychophysical thresholds and magnitude estimation for several sensory modalities were determined. The results of this study showed that topical capsaicin significantly and reversibly decreased the magnitude estimation of suprathreshold heat pain, laser pulses and amplitude of the LEPs. There was no statistically significant difference in light touch, deep pain and mechanical pain detection thresholds between the capsaicin- and vehicle-treated hands. It indicated that topical capsaicin caused a definite functional and reversible inactivation of A delta nociceptive afferent transmission. The decline in the magnitude estimation of laser pulses concomitantly with the attenuation of LEP amplitudes supports the hypothesis that some A delta afferents mediate noxious heat in humans. These findings demonstrate the usefulness of LEP in the physiological evaluation of nociceptive pathways and its potential usefulness in objectively documenting the effect of pharmacological treatment on pain perception. PMID:8826506

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

    PubMed

    Luft, Caroline Di Bernardi; Bhattacharya, Joydeep

    2015-01-01

    Recent studies showed that the visceral information is constantly processed by the brain, thereby potentially influencing cognition. One index of such process is the heartbeat evoked potential (HEP), an ERP component related to the cortical processing of the heartbeat. The HEP is sensitive to a number of factors such as motivation, attention, pain, which are associated with higher levels of arousal. However, the role of arousal and its associated brain oscillations on the HEP has not been characterized, yet it could underlie the previous findings. Here we analysed the effects of high- (HA) and low-arousal (LA) induction on the HEP. Further, we investigated the brain oscillations and their role in the HEP in response to HA and LA inductions. As compared to LA, HA was associated with a higher HEP and lower alpha oscillations. Interestingly, individual differences in the HEP modulation by arousal induction were correlated with alpha oscillations. In particular, participants with higher alpha power during the arousal inductions showed a larger HEP in response to HA compared to LA. In summary, we demonstrated that arousal induction affects the cortical processing of heartbeats; and that the alpha oscillations may modulate this effect. PMID:26503014

  19. A miniature microdrive for recording auditory evoked potentials from awake anurans.

    PubMed

    Mohammed, Haitham S; Radwan, Nasr M; Walkowiak, Wolfgang; Elsayed, Anwar A

    2013-09-01

    Electrical activity recording from the brains of awake animals is a corner stone in the study of the neurophysiological basis of behavior. To meet this need, a microelectrode driver suitable for the animal of interest has to be developed. In the present study a miniature microdrive was developed specifically for the leopard toad, Bufo regularis, however, it can be used for other small animals. The microdrive was designed to meet the following requirements: small size, light weight, simple and easy way of attaching and removing, advancing and withdrawing of microelectrode in the animal brain without rotation, can be reused and made from inexpensive materials. To assess the performance of the developed microdrive, we recorded auditory evoked potentials from different auditory centers in the toad's brain. The potentials were obtained from mesencephalic, diencephalic and telencephalic auditory sensitive areas in response to simple and complex acoustic stimuli. The synthetic acoustical tones introduced to the toad were carrying the dominant frequencies of their mating calls. PMID:23817637

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

    PubMed Central

    Luft, Caroline Di Bernardi; Bhattacharya, Joydeep

    2015-01-01

    Recent studies showed that the visceral information is constantly processed by the brain, thereby potentially influencing cognition. One index of such process is the heartbeat evoked potential (HEP), an ERP component related to the cortical processing of the heartbeat. The HEP is sensitive to a number of factors such as motivation, attention, pain, which are associated with higher levels of arousal. However, the role of arousal and its associated brain oscillations on the HEP has not been characterized, yet it could underlie the previous findings. Here we analysed the effects of high- (HA) and low-arousal (LA) induction on the HEP. Further, we investigated the brain oscillations and their role in the HEP in response to HA and LA inductions. As compared to LA, HA was associated with a higher HEP and lower alpha oscillations. Interestingly, individual differences in the HEP modulation by arousal induction were correlated with alpha oscillations. In particular, participants with higher alpha power during the arousal inductions showed a larger HEP in response to HA compared to LA. In summary, we demonstrated that arousal induction affects the cortical processing of heartbeats; and that the alpha oscillations may modulate this effect. PMID:26503014

  1. Visual Evoked Potential Using Head-Mounted Display Versus Cathode Ray Tube: A Pilot Study

    PubMed Central

    Choi, Hyo Seon; Im, Sang Hee; Kim, Yong Kyun

    2016-01-01

    Objective To present a new stimulation method based on the use of a head-mounted display (HMD) during pattern reversal visual evoked potential (PR-VEP) testing and to compare variables of HMD to those of conventional cathode ray tube (CRT). Methods Twenty-three normal subjects without visual problems were recruited. PR-VEPs were generated using CRT or HMD stimuli. VEP outcome measures included latencies (N75, P100, and N145) and peak-to-peak amplitudes (N75–P100 and P100–N145). Subjective discomfort associated with HMD was determined using a self-administered questionnaire. Results PR-VEPs generated by HMD stimuli showed typical triphasic waveforms, the components of which were found to be correlated with those obtained using conventional CRT stimuli. Self-administered discomfort questionnaires revealed that HMD was more comfortable in some aspects. It allowed subjects to concentrate better than CRT. Conclusion The described HMD stimulation can be used as an alternative to the standard CRT stimulation for PR-VEPs. PR-VEP testing using HMD has potential applications in clinical practice and visual system research because HMD can be used on a wider range of subjects compared to CRT. PMID:27152285

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

    PubMed

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

    2015-05-01

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

  3. Neurophysiological assessment of perceived image quality using steady-state visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Bosse, Sebastian; Acqualagna, Laura; Porbadnigk, Anne K.; Curio, Gabriel; Müller, Klaus-Robert; Blankertz, Benjamin; Wiegand, Thomas

    2015-09-01

    An approach to the neural measurement of perceived image quality using electroencephalography (EEG) is presented. 6 different images were tested on 6 different distortion levels. The distortions were introduced by a hybrid video encoder. The presented study consists of two parts: In a first part, subjects were asked to evaluate the quality of the test stimuli behaviorally during a conventional psychophysical test using a degradation category rating procedure. In a second part, subjects were presented undistorted and distorted texture images in a periodically alternating fashion at a fixed frequency. This alternating presentation elicits so called steady-state visual evoked potentials (SSVEP) as a brain response that can be measured on the scalp. The amplitude of modulations in the brain signals is significantly and strongly negatively correlated with the magnitude of visual impairment reported by the subjects. This neurophysiological approach to image quality assessment may potentially lead to a more objective evaluation, as behavioral approaches suffer from drawbacks such as biases, inter-subject variances and limitations to test duration.

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

    PubMed Central

    Majid, D. S. Adnan; Lewis, Christina

    2015-01-01

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

  5. The effect of anaesthesia on somatosensory evoked potential measurement in a rat model.

    PubMed

    Kortelainen, Jukka; Al-Nashash, Hasan; Vipin, Ashwati; Thow, Xin Yuan; All, Angelo

    2016-02-01

    Somatosensory evoked potentials (SEPs) are widely used to study the functional integrity of ascending sensory pathways. For animal studies, SEPs provide a convenient method to quantitatively assess the functionality of the nervous system with low invasiveness. Even though they are frequently used in animal models, little attention is paid to the fact that SEPs are vulnerable to contamination from experimental factors such as anaesthetic delivery. In this study, the effect of isoflurane on SEP measurement was investigated in a rat model. The aim was to find out the adjustments for anaesthetic delivery optimizing the quality of the recordings. Two aspects were studied: the effect of isoflurane dosage on the SEP parameters and on the repeatability of the measurements. The SEP quality was found to be best when 1.5% isoflurane concentration was used. This dosage resulted in the best signal-to-noise ratio and equal repeatability of the measurements compared with the others. Our findings can help in refining the anaesthetic protocols related to SEP recordings in a rat model and, by improving the quality of the measurements, potentially reducing the number of subjects needed to carry out studies. PMID:26025916

  6. Face-Evoked Steady-State Visual Potentials: Effects of Presentation Rate and Face Inversion

    PubMed Central

    Gruss, L. Forest; Wieser, Matthias J.; Schweinberger, Stefan R.; Keil, Andreas

    2012-01-01

    Face processing can be explored using electrophysiological methods. Research with event-related potentials has demonstrated the so-called face inversion effect, in which the N170 component is enhanced in amplitude and latency to inverted, compared to upright, faces. The present study explored the extent to which repetitive lower-level visual cortical engagement, reflected in flicker steady-state visual evoked potentials (ssVEPs), shows similar amplitude enhancement to face inversion. We also asked if inversion-related ssVEP modulation would be dependent on the stimulation rate at which upright and inverted faces were flickered. To this end, multiple tagging frequencies were used (5, 10, 15, and 20?Hz) across two studies (n?=?21, n?=?18). Results showed that amplitude enhancement of the ssVEP for inverted faces was found solely at higher stimulation frequencies (15 and 20?Hz). By contrast, lower frequency ssVEPs did not show this inversion effect. These findings suggest that stimulation frequency affects the sensitivity of ssVEPs to face inversion. PMID:23205009

  7. Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception.

    PubMed Central

    Frøbert, O; Arendt-Nielsen, L; Bak, P; Funch-Jensen, P; Bagger, J P

    1995-01-01

    Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus. PMID:8549932

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

    ERIC Educational Resources Information Center

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

    2013-01-01

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

  9. 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...

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

    PubMed Central

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

    2016-01-01

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

  11. Translational aspects of rectal evoked potentials: a comparative study in rats and humans

    PubMed Central

    Nissen, Thomas Dahl; Graversen, Carina; Coen, Steven J.; Hultin, Leif; Aziz, Qasim; Lykkesfeldt, Jens; Drewes, Asbjørn Mohr

    2013-01-01

    Inconsistencies between species has stunted the progress of developing new analgesics. To increase the success of translating results between species, improved comparable models are required. Twelve rats received rectal balloon distensions on 2 different days separated by 24.3 (SD 24.6) days. Rectal balloon distensions were also performed in 18 humans (mean age: 34 yr; range: 21–56 yr; 12 men) on two separate occasions, separated by 9.3 (SD 5.5) days. In rats, cerebral evoked potentials (CEPs) were recorded by use of implanted skull-electrodes to distension pressure of 80 mmHg. In humans surface electrodes and individualized pressure, corresponding to pain detection threshold, were used. Comparison of morphology was assessed by wavelet analysis. Within- and between-day reproducibility was assessed in terms of latencies, amplitudes, and frequency content. In rats CEPs showed triphasic morphology. No differences in latencies, amplitudes, and power distribution were seen within or between days (all P ≥ 0.5). Peak-to-peak amplitude between the first positive and negative potential were the most reproducible characteristic within and between days (evaluated by intraclass correlation coefficients, ICC) (ICC = 0.99 and ICC = 9.98, respectively). In humans CEPs showed a triphasic morphology. No differences in latencies, amplitudes, or power distribution were seen within or between days (all P ≥ 0.2). Latency to the second negative potential (ICC = 0.98) and the second positive potential (ICC = 0.95) was the most reproducible characteristic within and between days. A unique and reliable translational platform was established assessing visceral sensitivity in rats and humans, which may improve the translational process of developing new drugs targeting visceral pain. PMID:23703652

  12. 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 ...

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

    PubMed Central

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

    2014-01-01

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

  14. Stimulus and recording variables and their effects on mammalian vestibular evoked potentials

    NASA Technical Reports Server (NTRS)

    Jones, Sherri M.; Subramanian, Geetha; Avniel, Wilma; Guo, Yuqing; Burkard, Robert F.; Jones, Timothy A.

    2002-01-01

    Linear vestibular evoked potentials (VsEPs) measure the collective neural activity of the gravity receptor organs in the inner ear that respond to linear acceleration transients. The present study examined the effects of electrode placement, analog filtering, stimulus polarity and stimulus rate on linear VsEP thresholds, latencies and amplitudes recorded from mice. Two electrode-recording montages were evaluated, rostral (forebrain) to 'mastoid' and caudal (cerebellum) to 'mastoid'. VsEP thresholds and peak latencies were identical between the two recording sites; however, peak amplitudes were larger for the caudal recording montage. VsEPs were also affected by filtering. Results suggest optimum high pass filter cutoff at 100-300 Hz, and low pass filter cutoff at 10,000 Hz. To evaluate stimulus rate, linear jerk pulses were presented at 9.2, 16, 25, 40 and 80 Hz. At 80 Hz, mean latencies were longer (0.350-0.450 ms) and mean amplitudes reduced (0.8-1.8 microV) for all response peaks. In 50% of animals, late peaks (P3, N3) disappeared at 80 Hz. The results offer options for VsEP recording protocols. Copyright 2002 Elsevier Science B.V.

  15. Amphibious auditory evoked potentials in four North American Testudines genera spanning the aquatic-terrestrial spectrum.

    PubMed

    Zeyl, Jeffrey N; Johnston, Carol E

    2015-10-01

    Animals exhibit unique hearing adaptations in relation to the habitat media in which they reside. This study was a comparative analysis of auditory specialization in relation to habitat medium in Testudines, a taxon that includes both highly aquatic and fully terrestrial members. Evoked potential audiograms were collected in four species groups representing diversity along the aquatic-terrestrial spectrum: terrestrial and fossorial Gopherus polyphemus, terrestrial Terrapene carolina carolina, and aquatic Trachemys scripta and Sternotherus (S. odoratus and S. minor). Additionally, underwater sensitivity was tested in T. c. carolina, T. scripta, and Sternotherus with tympana submerged just below the water surface. In aerial audiograms, T. c. carolina were most sensitive, with thresholds 18 dB lower than Sternotherus. At 100-300 Hz, thresholds in T. c. carolina, G. polyphemus, and T. scripta were similar to each other. At 400-800 Hz, G. polyphemus thresholds were elevated to 11 dB above T. c. carolina. The underwater audiograms of T. c. carolina, T. scripta, and Sternotherus were similar. The results suggest aerial hearing adaptations in emydids and high-frequency hearing loss associated with seismic vibration detection in G. polyphemus. The underwater audiogram of T. c. carolina could reflect retention of ancestral aquatic auditory function. PMID:26194768

  16. Overnight changes in waking auditory evoked potential amplitude reflect altered sleep homeostasis in major depression

    PubMed Central

    Goldstein, Michael R.; Plante, David T.; Hulse, Brad K.; Sarasso, Simone; Landsness, Eric C.; Tononi, Giulio; Benca, Ruth M.

    2011-01-01

    Objective Sleep homeostasis is altered in major depressive disorder (MDD). Pre-to post-sleep decline in waking auditory evoked potential (AEP) amplitude has been correlated with sleep slow wave activity (SWA), suggesting that overnight changes in waking AEP amplitude are homeostatically regulated in healthy individuals. This study investigated whether the overnight change in waking AEP amplitude and its relation to SWA is altered in MDD. Method Using 256-channel high-density electroencephalography, all-night sleep polysomnography and single-tone waking AEPs pre-and post-sleep were collected in 15 healthy controls (HC) and 15 non-medicated individuals with MDD. Results N1 and P2 amplitudes of the waking AEP declined after sleep in the HC group, but not in MDD. The reduction in N1 amplitude also correlated with fronto-central SWA in the HC group, but a comparable relationship was not found in MDD, despite equivalent SWA between groups. No pre-to post-sleep differences were found for N1 or P2 latencies in either group. These findings were not confounded by varying levels of alertness or differences in sleep variables between groups. Conclusion MDD involves altered sleep homeostasis as measured by the overnight change in waking AEP amplitude. Future research is required to determine the clinical implications of these findings. PMID:22097901

  17. Characterization of neurologic injury using novel morphological analysis of Somatosensory Evoked Potentials.

    PubMed

    Madhok, Jai; Iyer, Shrivats; Thakor, Nitish V; Maybhate, Anil

    2010-01-01

    This paper describes an innovative, easy-to-interpret, clinically translatable tool for analysis of Somatosensory Evoked Potentials (SSEPs). Unlike traditional analysis, which involves peak-to-peak amplitude and latency calculation, this method, phase space analysis, analyzes the overall morphology of the SSEP, and includes greater information. The SSEP is plotted in phase space (x-dot vs. x), which leads to an approximately spiral curve. The area swept out by this curve is termed the Phase Space Area (PSA). As PSA calculation involves numerical differentiation, we present a comparison of two different approaches to combat noise amplification: finite-window smoothing, and total variation regularization (TVR) of the numerical derivative. These methods are applied to simulated SSEPs. The efficacy of these methods in performing noise-reduction is assessed and compared with ensemble averaging. While TVR gives a reasonably robust approximation of the derivative, Gaussian smoothing of the derivative offers the best trade-off between the number of signal sweeps required to be averaged, close approximation of the SSEP derivative, and optimal estimation of the PSA. We validate this method by analyzing non-characteristic SSEPs that have indistinguishable peaks as is frequently seen in cases of underlying neurologic injury such as hypoxic-ischemic encephalopathy. PMID:21095700

  18. Ocular vestibular evoked myogenic potentials to air conduction (AC oVEMP): useful in clinical practice?

    PubMed

    Walther, L E; Rogowski, M; Hörmann, K; Schaaf, H; Löhler, J

    2011-01-01

    Cervical vestibular-evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) stimuli can be used to measure otolith function using air (AC) and bone conducted (BC) stimuli. Cervical VEMPs reflect saccular function and can be recorded using air conduction (AC), whereas oVEMPs reflect probably predominantly utricular function. Air- and bone-conducted vibration can be used, because AC oVEMP methodology seems to be fast and simple in clinical practice to measure otolith function. In this study we discuss the advantages and problems of AC oVEMP stimulation. AC oVEMP can be easily and quickly obtained within a few seconds. N10 (first negative peak) and p15 (first positive peak) latencies may be used as parameters for clinical interpretation but amplitude fluctuations are relatively large. For daily clinical use of VEMP visualization in a normogram seems feasible. Especially the AC oVEMP methodology (100 dB nHL, tone burst 500 Hz) is fast and efficient in clinical practice to measure otolith function, predominantly utricular function. PMID:22078282

  19. Comparison of the effects of barbiturate, benzodiazepine and ketamine on visual evoked potentials in rabbits.

    PubMed

    Castro-Júnior, J; Resende, L A L; Bertotti, M F Z; Fonseca, R G; Zanchetta, S; Schelp, A O

    2005-01-01

    The aim of this study was to compare the effects of barbiturate, benzodiazepine and ketamine on flash-evoked potentials (F-VEP) in adult rabbits. A total of 36 animals were studied, 16 after pentobarbital endovenous (EV) infusion, 10 after midazolam EV administration, and 10 after ketamine EV infusion. Pentobarbital induced triphasic F-VEP, first negative (N1), second positive (P1), third negative (N2) waves, all with large amplitudes and P1 with well-defined morphology. Mean P1 latency was 33ms. Midazolam induced similar but less defined triphasic waves, with mean latency of 27ms. Ketamine induced poliphasic and poorly defined F-VEP, with mean first positive (P1) latency of 27ms. Statistical analysis showed more elongated latency for the pentobarbital group than the midazolam and ketamine groups. The results of this study suggest that the pharmacological effects of pentobarbital and midazolam on GABA neurotransmission in rabbit visual cortex may be different; another neurotransmission system, possibly cholinergic, may be involved. The ketamine effect seen in rabbit visual cortex seems to be different from pentobarbital and midazolam. PMID:16218192

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

    PubMed

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

    2016-05-15

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

  1. Ketamine-Based Anesthetic Protocols and Evoked Potential Monitoring: A Risk/Benefit Overview.

    PubMed

    Stoicea, Nicoleta; Versteeg, Gregory; Florescu, Diana; Joseph, Nicholas; Fiorda-Diaz, Juan; Navarrete, Víctor; Bergese, Sergio D

    2016-01-01

    Since its discovery, ketamine, a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist related to phencyclidine, has been linked to multiple adverse reactions sometimes described as "out of body" and "near death experiences," including emergence phenomena, delusions, hallucinations, delirium, and confusion. Due to these effects, ketamine has been withdrawn from mainstream anesthetic use in adult patients. Evoked potentials (EPs) are utilized to monitor neural pathways during surgery, detect intraoperative stress or damage, detect and define the level of neural lesions, and define abnormalities. Unfortunately, many of the volatile anesthetics commonly used during spinal and neurologic procedures suppress EP amplitude and monitoring. Ketamine has been found in several preclinical and clinical studies to actually increase EP amplitude and thus has been used as an analgesic adjunct in procedures where EP monitoring is critical. Once the gap in our knowledge of ketamine's risks has been sufficiently addressed in animal models, informed clinical trials should be conducted in order to properly incorporate ketamine-based anesthetic regimens during EP-monitored neurosurgeries. PMID:26909017

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

    PubMed

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

    2015-05-01

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

  3. Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury.

    PubMed

    Iyer, Shrivats; Maybhate, Anil; Presacco, Alessandro; All, Angelo H

    2010-11-30

    The motor evoked potential (MEP) is an electrical response of peripheral neuro-muscular pathways to stimulation of the motor cortex. MEPs provide objective assessment of electrical conduction through the associated neural pathways, and therefore detect disruption due to a nervous system injury such as spinal cord injury (SCI). In our studies of SCI, we developed a novel, multi-channel set-up for MEP acquisition in rat models. Unlike existing electrophysiological systems for SCI assessment, the set-up allows for multi-channel MEP acquisition from all limbs of rats and enables longitudinal monitoring of injury and treatment for in vivo models of experimental SCI. The article describes the development of the set-up and discusses its capabilities to acquire MEPs in rat models of SCI. We demonstrate its use for MEP acquisition under two types of anesthesia as well as a range of cortical stimulation parameters, identifying parameters yielding consistent and reliable MEPs. To validate our set-up, MEPs were recorded from a group of 10 rats before and after contusive SCI. Upon contusion with moderate severity (12.5mm impact height), MEP amplitude decreased by 91.36±6.03%. A corresponding decline of 93.8±11.4% was seen in the motor behavioral score (BBB), a gold standard in rodent models of SCI. PMID:20832429

  4. Effect of MOG Sensitization on Somatosensory Evoked Potential in Lewis Rats

    PubMed Central

    All, Angelo H.; Walczak, Piotr; Agrawal, Gracee; Gorelik, Michael; Lee, Christopher; Thakor, Nitish V.; Bulte, Jeff W.M.; Kerr, Douglas A.

    2009-01-01

    Myelin oligodendrocyte glycoprotein (MOG) is commonly used as an immunogen to induce an immune response against endogenous myelin, thereby modeling multiple sclerosis in rodents. When MOG is combined with complete Freund’s adjuvant (CFA), multifocal, multiphasic disease ensues; whereas when MOG is combined with incomplete Freund’s adjuvant (IFA), clinical disease is usually absent. MOG-IFA immunized animals can be induced to have neurological disease after intraspinal injections of cytokines and ethidium bromide (EtBr). In this study, we investigated whether MOG-IFA immunized rats exhibited subclinical injury as defined by Somatosensory Evoked Potential (SEP) recordings. The titration of Anti-MOG-125 antibodies showed robust peripheral mounting of immune response against myelin in MOG-immunized rats. However the SEP measures showed no significant change over time. Upon injecting cytokine-EtBr in the spinal cord after MOG sensitization, the SEP recordings showed reduced amplitude and prolonged latency, suggestive of axonal injury and demyelination in the dorsal column, respectively. These findings were later confirmed using T2-weighted MRI and histological hematoxilin-eosin stain of the spinal cord. This report establishes that MOG-IFA immunization alone does not alter neuronal conduction in SEP-related neural-pathways and that longitudinal in-vivo SSEP recordings provide a sensitive read-out for focal myelitis (MOG-IFA & intraspinal cytokine-EtBr) in rats. PMID:19423134

  5. Effect of MOG sensitization on somatosensory evoked potential in Lewis rats.

    PubMed

    All, Angelo H; Walczak, Piotr; Agrawal, Gracee; Gorelik, Michael; Lee, Christopher; Thakor, Nitish V; Bulte, Jeff W M; Kerr, Douglas A

    2009-09-15

    Myelin oligodendrocyte glycoprotein (MOG) is commonly used as an immunogen to induce an immune response against endogenous myelin, thereby modeling multiple sclerosis in rodents. When MOG is combined with complete Freund's adjuvant (CFA), multifocal, multiphasic disease ensues; whereas when MOG is combined with incomplete Freund's adjuvant (IFA), clinical disease is usually absent. MOG-IFA immunized animals can be induced to have neurological disease after intraspinal injections of cytokines and ethidium bromide (EtBr). In this study, we investigated whether MOG-IFA immunized rats exhibited subclinical injury as defined by somatosensory evoked potential (SEP) recordings. The titration of anti-MOG-125 antibodies showed robust peripheral mounting of immune response against myelin in MOG-immunized rats. However the SEP measures showed no significant change over time. Upon injecting cytokine-EtBr in the spinal cord after MOG sensitization, the SEP recordings showed reduced amplitude and prolonged latency, suggestive of axonal injury and demyelination in the dorsal column, respectively. These findings were later confirmed using T2-weighted MRI and histological hematoxylin-eosin stain of the spinal cord. This report establishes that MOG-IFA immunization alone does not alter neuronal conduction in SEP-related neural-pathways and that longitudinal in-vivo SEP recordings provide a sensitive read-out for focal myelitis (MOG-IFA and intraspinal cytokine-EtBr) in rats. PMID:19423134

  6. Evoked potential and behavioral outcomes for experimental autoimmune encephalomyelitis in Lewis rats.

    PubMed

    All, Angelo H; Agrawal, Gracee; Walczak, Piotr; Maybhate, Anil; Bulte, Jeff W M; Kerr, Douglas A

    2010-10-01

    A reliable outcome measurement is needed to assess the effects of experimental lesions in the rat spinal cord as well as to assess the benefits of therapies designed to modulate them. The Basso, Beattie, and Bresnahan (BBB) behavioral scores can be indicative of the functionality in motor pathways. However, since lesions are often induced in the more accessible dorsal parts associated with the sensory pathways, the BBB scores may not be ideal measure of the disability. We propose somatosensory evoked potential (SEP) as a complementary measure to assess the integrity of sensory pathways. We used the focal experimental autoimmune encephalomyelitis (EAE) model, in which focal demyelinating lesions were induced by injecting cytokine-ethidium bromide into dorsal white matter after MOG-IFA immunization. Both the SEP and BBB measures reflected injury; however, the SEP was uniformly and consistently altered after the injury whereas the BBB varied widely. The results suggest that the SEP measures are more sensitive and reliable markers of focal spinal cord demyelination compared to the behavioral measures like the BBB score. PMID:20508959

  7. Effect of MOG sensitization on somatosensory evoked potential in Lewis rats

    PubMed Central

    All, Angelo H.; Walczak, Piotr; Agrawal, Gracee; Gorelik, Michael; Lee, Christopher; Thakor, Nitish V.; Bulte, Jeff W.M.; Kerr, Douglas A.

    2011-01-01

    Myelin oligodendrocyte glycoprotein (MOG) is commonly used as an immunogen to induce an immune response against endogenous myelin, thereby modeling multiple sclerosis in rodents. When MOG is combined with complete Freund's adjuvant (CFA), multifocal, multiphasic disease ensues; whereas when MOG is combined with incomplete Freund's adjuvant (IFA), clinical disease is usually absent. MOG–IFA immunized animals can be induced to have neurological disease after intraspinal injections of cytokines and ethidium bromide (EtBr). In this study, we investigated whether MOG–IFA immunized rats exhibited subclinical injury as defined by somatosensory evoked potential (SEP) recordings. The titration of anti-MOG-125 antibodies showed robust peripheral mounting of immune response against myelin in MOG-immunized rats. However the SEP measures showed no significant change over time. Upon injecting cytokine–EtBr in the spinal cord after MOG sensitization, the SEP recordings showed reduced amplitude and prolonged latency, suggestive of axonal injury and demyelination in the dorsal column, respectively. These findings were later confirmed using T2-weighted MRI and histological hematoxylin–eosin stain of the spinal cord. This report establishes that MOG–IFA immunization alone does not alter neuronal conduction in SEP-related neural-pathways and that longitudinal in-vivo SEP recordings provide a sensitive read-out for focal myelitis (MOG–IFA and intraspinal cytokine–EtBr) in rats. PMID:20508959

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

    PubMed

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

    2011-01-01

    Spinal cord injury (SCI) causes a number of physiological and neurological changes resulting in loss of sensorimotor function. Recent work has shown that the central nervous system is capable of plastic behaviors post-injury, including axonal regrowth and cortical remapping. Functional integrity of afferent sensory pathways can be quantified using cortical somatosensory evoked potentials (SSEPs) recorded upon peripheral limb stimulation. We implanted 15 rats with transcranial screw electrodes and recorded SSEPs from cortical regions corresponding to each limb before and after a mild or moderate contusion injury. We report a post-injury increase in the mean amplitude of cortical SSEPs upon forelimb stimulation. SSEP amplitudes for mild and moderate SCI groups increased by 183% ± 95% and 107% ± 38% over baseline, respectively, while hindlimb SSEPs decreased by 58% ± 14% and 79% ± 4%. In addition, we report increased SSEP amplitude measured from the anatomically adjacent hindlimb region upon forelimb stimulation (increase of 90% ± 19%). Our results show that previously allocated hindlimb cortical regions are now activated by forelimb stimulation, suggesting an expansion in the area of cortical forelimb representation into hindlimb regions after an injury. This result is indicative of adaptive plasticity in undamaged areas of the CNS following SCI. PMID:22254728

  9. Visuocortical Changes During Delay and Trace Aversive Conditioning: Evidence From Steady-State Visual Evoked Potentials

    PubMed Central

    Miskovic, Vladimir; Keil, Andreas

    2015-01-01

    The visual system is biased towards sensory cues that have been associated with danger or harm through temporal co-occurrence. An outstanding question about conditioning-induced changes in visuocortical processing is the extent to which they are driven primarily by top-down factors such as expectancy or by low-level factors such as the temporal proximity between conditioned stimuli and aversive outcomes. Here, we examined this question using two different differential aversive conditioning experiments: participants learned to associate a particular grating stimulus with an aversive noise that was presented either in close temporal proximity (delay conditioning experiment) or after a prolonged stimulus-free interval (trace conditioning experiment). In both experiments we probed cue-related cortical responses by recording steady-state visual evoked potentials (ssVEPs). Although behavioral ratings indicated that all participants successfully learned to discriminate between the grating patterns that predicted the presence versus absence of the aversive noise, selective amplification of population-level responses in visual cortex for the conditioned danger signal was observed only when the grating and the noise were temporally contiguous. Our findings are in line with notions purporting that changes in the electrocortical response of visual neurons induced by aversive conditioning are a product of Hebbian associations among sensory cell assemblies rather than being driven entirely by expectancy-based, declarative processes. PMID:23398582

  10. A lower limb exoskeleton control system based on steady state visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Kwak, No-Sang; Müller, Klaus-Robert; Lee, Seong-Whan

    2015-10-01

    Objective. We have developed an asynchronous brain-machine interface (BMI)-based lower limb exoskeleton control system based on steady-state visual evoked potentials (SSVEPs). Approach. By decoding electroencephalography signals in real-time, users are able to walk forward, turn right, turn left, sit, and stand while wearing the exoskeleton. SSVEP stimulation is implemented with a visual stimulation unit, consisting of five light emitting diodes fixed to the exoskeleton. A canonical correlation analysis (CCA) method for the extraction of frequency information associated with the SSVEP was used in combination with k-nearest neighbors. Main results. Overall, 11 healthy subjects participated in the experiment to evaluate performance. To achieve the best classification, CCA was first calibrated in an offline experiment. In the subsequent online experiment, our results exhibit accuracies of 91.3 ± 5.73%, a response time of 3.28 ± 1.82 s, an information transfer rate of 32.9 ± 9.13 bits/min, and a completion time of 1100 ± 154.92 s for the experimental parcour studied. Significance. The ability to achieve such high quality BMI control indicates that an SSVEP-based lower limb exoskeleton for gait assistance is becoming feasible.

  11. Abnormal recovery function of somatosensory evoked potentials in patients with primary insomnia.

    PubMed

    Huang, Zhaoyang; Zhan, Shuqin; Li, Ning; Ding, Yan; Wang, Yuping

    2012-08-15

    Neurobiological correlates underlying insomnia are poorly understood. The hyperarousal of the central nervous system indicates that cortical excitability may be abnormal in patients with insomnia. The purpose of the present study was to investigate changes in cortical excitability by examining the recovery function of median nerve somatosensory evoked potentials (SEPs) in patients with primary insomia (PI). We studied the recovery function of median nerve SEPs in 12 medication-naive PI patients and in 12 age- and sex-matched healthy subjects. SEPs in response to single stimulus and paired stimuli at interstimulus intervals (ISIs) of 20, 60, 100 and 150 ms were recorded. The recovery function of the cortical components of frontal P20 and parietal N20 showed significantly reduced suppression in PI patients as compared to healthy controls. In conclusion, this is the first study investigating changes in cortical excitability in PI patients by examining the recovery function of median nerve SEPs. The present study suggests that cortical excitability is increased in PI patients. Dysfunction of inhibitory GABAergic interneurons of the cerebral cortex might contribute to the increased cortical excitability in PI patients. PMID:22424903

  12. Diagnostic Value of Vestibular Evoked Myogenic Potentials in Endolymphatic Hydrops: A Meta-Analysis

    PubMed Central

    Zhang, Sulin; Leng, Yangming; Liu, Bo; Shi, Hao; Lu, Meixia; Kong, Weijia

    2015-01-01

    In this study, we evaluated the clinical diagnostic value of vestibular evoked myogenic potentials (VEMPs) for endolymphatic hydrops (EH) by systematic review and Meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio and area under summary receiver operating characteristic curves (AUC) were calculated. Subgroup analysis and publication bias assessment were also conducted. The pooled sensitivity and the specificity were 49% (95% CI: 46% to 51%) and 95% (95% CI: 94% to 96%), respectively. The pooled positive likelihood ratio was 18.01 (95% CI: 9.45 to 34.29) and the pooled negative likelihood ratio was 0.54 (95% CI: 0.47 to 0.61). AUC was 0.78 and the pooled diagnostic odds ratio of VEMPs was 39.89 (95% CI: 20.13 to 79.03). In conclusion, our present meta-analysis has demonstrated that VEMPs test alone is not sufficient for Meniere’s disease or delayed endolymphatic hydrops diagnosis, but that it might be an important component of a test battery for diagnosing Meniere’s disease or delayed endolymphatic hydrops. Moreover, VEMPs, due to its high specificity and non-invasive nature, might be used as a screening tool for EH. PMID:26455332

  13. A method to detect progression of glaucoma using the multifocal visual evoked potential technique

    PubMed Central

    Wangsupadilok, Boonchai; Kanadani, Fabio N.; Grippo, Tomas M.; Liebmann, Jeffrey M.; Ritch, Robert; Hood, Donald C.

    2010-01-01

    Purpose To describe a method for monitoring progression of glaucoma using the multifocal visual evoked potential (mfVEP) technique. Methods Eighty-seven patients diagnosed with open-angle glaucoma were divided into two groups. Group I, comprised 43 patients who had a repeat mfVEP test within 50 days (mean 0.9 ± 0.5 months), and group II, 44 patients who had a repeat test after at least 6 months (mean 20.7 ± 9.7 months). Monocular mfVEPs were obtained using a 60-sector pattern reversal dartboard display. Monocular and interocular analyses were performed. Data from the two visits were compared. The total number of abnormal test points with P < 5% within the visual field (total scores) and number of abnormal test points within a cluster (cluster size) were calculated. Data for group I provided a measure of test–retest variability independent of disease progression. Data for group II provided a possible measure of progression. Results The difference in the total scores for group II between visit 1 and visit 2 for the interocular and monocular comparison was significant (P < 0.05) as was the difference in cluster size for the interocular comparison (P < 0.05). Group I did not show a significant change in either total score or cluster size. Conclusion The change in the total score and cluster size over time provides a possible method for assessing progression of glaucoma with the mfVEP technique. PMID:18830654

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

    NASA Astrophysics Data System (ADS)

    Houser, Dorian; Finneran, James

    2005-04-01

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

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

    PubMed Central

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

    2013-01-01

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

  16. Suppression of EEG visual-evoked potentials in rats via neuromodulatory focused ultrasound

    PubMed Central

    Kim, Hyungmin; Park, Michael Y.; Lee, Stephanie D.; Lee, Wonhye; Chiu, Alan; Yoo, Seung-Schik

    2015-01-01

    We investigated the use of pulsed low-intensity focused ultrasound (FUS) to suppress the visual neural response induced by light stimulation in rodents. FUS was administered transcranially to the rat visual cortex using different acoustic intensities and pulsing duty cycles. The visual evoked potentials (VEP) generated by an external strobe light stimulation were measured three times before, once during, and five times after the sonication. The VEP magnitude was suppressed during the sonication using a 5% duty cycle (pulse-repetition frequency of 100 Hz) and spatial-peak pulse-average acoustic intensity of 3 W/cm2; however, this suppressive effect was not present when a lower acoustic intensity and duty cycle were used. The application of a higher intensity and duty cycle resulted in a slight elevation of VEP magnitude, which suggested excitatory neuromodulation. Our findings demonstrate that the application of pulsed FUS to the region-specific brain area not only suppresses its excitability, but also can enhance the excitability depending on the acoustic intensity and rate of energy deposition. This bimodal feature of FUS-mediated neuromodulation, which has been predicted by numerical models on neural membrane capacitance change by the external acoustic pressure waves, suggests its versatility for neurotherapeutic applications. PMID:25646585

  17. Ketamine-Based Anesthetic Protocols and Evoked Potential Monitoring: A Risk/Benefit Overview

    PubMed Central

    Stoicea, Nicoleta; Versteeg, Gregory; Florescu, Diana; Joseph, Nicholas; Fiorda-Diaz, Juan; Navarrete, Víctor; Bergese, Sergio D.

    2016-01-01

    Since its discovery, ketamine, a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist related to phencyclidine, has been linked to multiple adverse reactions sometimes described as “out of body” and “near death experiences,” including emergence phenomena, delusions, hallucinations, delirium, and confusion. Due to these effects, ketamine has been withdrawn from mainstream anesthetic use in adult patients. Evoked potentials (EPs) are utilized to monitor neural pathways during surgery, detect intraoperative stress or damage, detect and define the level of neural lesions, and define abnormalities. Unfortunately, many of the volatile anesthetics commonly used during spinal and neurologic procedures suppress EP amplitude and monitoring. Ketamine has been found in several preclinical and clinical studies to actually increase EP amplitude and thus has been used as an analgesic adjunct in procedures where EP monitoring is critical. Once the gap in our knowledge of ketamine's risks has been sufficiently addressed in animal models, informed clinical trials should be conducted in order to properly incorporate ketamine-based anesthetic regimens during EP-monitored neurosurgeries. PMID:26909017

  18. An online brain-computer interface using non-flashing visual evoked potentials.

    PubMed

    Liu, Tao; Goldberg, Leslie; Gao, Shangkai; Hong, Bo

    2010-06-01

    Not until recently have motion-onset visual evoked potentials (mVEPs) been explored as a modality for brain-computer interface (BCI) applications. In this study, the first online BCI system based on mVEPs is presented, in which selection is discerned by subjects' focused attention to the moving cursor at a target virtual button. An adaptive approach was used to adjust the number of trial presentations according to the participants' online performance. With the EEG signal acquired from only a single channel, an acceptable information transfer rate of 42.1 bits min(-1) was achieved, averaged by 12 subjects. Furthermore, an online application for the Google search system was developed based on this paradigm. The promising results, that all of 12 participants were able to operate the system freely, validate the feasibility of a practical motion-onset VEP-based BCI which could be embedded into computer screen elements, such as menu, button and icon, for various applications. PMID:20404396

  19. An online brain-computer interface using non-flashing visual evoked potentials

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Goldberg, Leslie; Gao, Shangkai; Hong, Bo

    2010-06-01

    Not until recently have motion-onset visual evoked potentials (mVEPs) been explored as a modality for brain-computer interface (BCI) applications. In this study, the first online BCI system based on mVEPs is presented, in which selection is discerned by subjects' focused attention to the moving cursor at a target virtual button. An adaptive approach was used to adjust the number of trial presentations according to the participants' online performance. With the EEG signal acquired from only a single channel, an acceptable information transfer rate of 42.1 bits min-1 was achieved, averaged by 12 subjects. Furthermore, an online application for the Google search system was developed based on this paradigm. The promising results, that all of 12 participants were able to operate the system freely, validate the feasibility of a practical motion-onset VEP-based BCI which could be embedded into computer screen elements, such as menu, button and icon, for various applications.

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

    PubMed

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

    1994-01-01

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

  1. Cholinergic gating of hippocampal auditory evoked potentials in freely moving rats.

    PubMed

    Klinkenberg, Inge; Sambeth, Anke; Blokland, Arjan

    2013-08-01

    As perturbations in auditory filtering appear to be a candidate trait marker of schizophrenia, there has been considerable interest in the development of translational rat models to elucidate the underlying neural and neurochemical mechanisms involved in sensory gating. This is the first study to investigate the effects of the non-selective muscarinic antagonist scopolamine, the muscarinic M1 antagonist biperiden and the cholinesterase inhibitor donepezil (also in combination with scopolamine and biperiden) on auditory evoked potentials (AEPs) and sensory gating. In the saline condition, only the N50 peak displayed sensory gating. Scopolamine and biperiden both disrupted sensory gating by increasing N50 amplitude for the S2 click. Donepezil was able to fully reverse the effects of biperiden on N50 sensory gating, but had residual effects when combined with scopolamine; i.e., it enhanced sensory gating by increasing N50 amplitude of the S1 stimulus. Donepezil by itself improved sensory gating by enhancing N50 amplitude of S1, and reducing N50 amplitude of the S2 click. In conclusion, due to its relatively more selective effects biperiden is to be preferred over scopolamine as a means for pharmacologically inducing cholinergic impairments in auditory processing in healthy rats. Changes in auditory processing and sensory gating induced by cholinergic drugs may serve as a translational model for aging instead of schizophrenia. PMID:22974558

  2. Attachment style moderates partner presence effects on pain: a laser-evoked potentials study

    PubMed Central

    Paloyelis, Yannis; Condon, Heather; Jenkinson, Paul M.; Williams, Steven C. R.; Fotopoulou, Aikaterini

    2015-01-01

    Social support is crucial for psychological and physical well-being. Yet, in experimental and clinical pain research, the presence of others has been found to both attenuate and intensify pain. To investigate the factors underlying these mixed effects, we administered noxious laser stimuli to 39 healthy women while their romantic partner was present or absent, and measured pain ratings and laser-evoked potentials (LEPs) to assess the effects of partner presence on subjective pain experience and underlying neural processes. Further, we examined whether individual differences in adult attachment style (AAS), alone or in interaction with the partner’s level of attentional focus (manipulated to be either on or away from the participant) might modulate these effects. We found that the effects of partner presence vs absence on pain-related measures depended on AAS but not partner attentional focus. The higher participants’ attachment avoidance, the higher pain ratings and N2 and P2 local peak amplitudes were in the presence compared with the absence of the romantic partner. As LEPs are thought to reflect activity relating to the salience of events, our data suggest that partner presence may influence the perceived salience of events threatening the body, particularly in individuals who tend to mistrust others. PMID:25556212

  3. Optimizing the bandpass filter for acoustic stimuli in recording ocular vestibular-evoked myogenic potentials.

    PubMed

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

    2013-05-10

    This study aimed to determine the optimal bandpass filter (BPF) setting for acoustic stimuli in recording the ocular vestibular-evoked myogenic potential (oVEMP). Twelve healthy volunteers underwent oVEMP tests using acoustic stimuli with various high-pass filters (1, 10 and 100Hz) and low-pass filters (500, 1000 and 2000Hz). Initially, various effects of high-pass filter on the oVEMPs were examined under Conditions A (BPF of 1-1000Hz), B (BPF of 10-1000Hz) and C (BPF of 100-1000Hz). Of these conditions, Condition A showed 100% response rate and had larger nI-pI amplitude than Conditions B and C. Thus, Condition A was selected for subsequent analysis of the various effects of low-pass filter on the oVEMPs. However, Condition A (BPF of 1-1000Hz) did not significantly differ from Conditions D (BPF of 1-500Hz) and E (BPF of 1-2000Hz) in terms of the latencies and amplitudes of oVEMPs. Condition A thus is supposed to be the optimal recording condition for oVEMPs. In conclusion, the optimal BPF setting for acoustic stimuli in recording oVEMPs is suggested to be between 1 and 1000Hz. PMID:23523646

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

    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.

  5. Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses

    PubMed Central

    Huang, Bowan; Liang, Feixue; Zhong, Lei; Lin, Minlin; Yang, Juan; Yan, Linqing; Xiao, Jinfan; Xiao, Zhongju

    2015-01-01

    Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, its unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (?L and ?I) were extracted during anesthesia. ?L and ?I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ?L and ?I. However, ?L was changed by the hypothermia, whereas ?I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ?L monitors the effect of hypothermia on nerve fibers, and ?I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ?I monitors the anesthesia effect on synapses. PMID:26246365

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

    PubMed

    Kamida, Tohru; Baba, Hiroshi; Ono, Kenji; Yonekura, Masato; Fujiki, Minoru; Kobayashi, Hidenori

    2003-09-01

    Five hemiplegic patients with intractable epilepsy were studied with transcranial magnetic stimulation (TMS) before and after various surgical treatments. These patients had unilateral widespread cerebral lesions acquired at various times, including congenital, infantile and childhood injury. Motor evoked potentials (MEPs) of the abductor pollicis brevis (APB) muscles were simultaneously recorded on both sides following TMS of the motor cortex in the respective hemisphere using a figure-8 or circular coil. In all patients with congenital disease, the abolition of motor function in the affected hemisphere was estimated by magnetic MEPs, and the hemiplegia did not deteriorate after functional hemispherectomy (HS) was performed in two of them. In two patients with acquired disease, HS was not performed because it was shown by magnetic maps that the motor function in the affected hemisphere remained. Furthermore, it was shown by electric MEPs using subdural electrodes that a patient who had had encephalitis in early childhood had a reorganised motor area in the parietal cortex of the affected hemisphere. The present findings indicate that magnetic MEPs are a very useful non-invasive method of assessing whether the motor area in the affected hemisphere can be resected in hemiplegic patients with intractable epilepsy. PMID:12915083

  7. Selective attention to stimulus location modulates the steady-state visual evoked potential.

    PubMed Central

    Morgan, S T; Hansen, J C; Hillyard, S A

    1996-01-01

    Steady-state visual evoked potentials (SSVEPs) were recorded from the scalp of human subjects who were cued to attend to a rapid sequence of alphanumeric characters presented to one visual half-field while ignoring a concurrent sequence of characters in the opposite half-field. These two-character sequences were each superimposed upon a small square background that was flickered at a rate of 8.6 Hz in one half-field and 12 Hz in the other half-field. The amplitude of the frequency-coded SSVEP elicited by either of the task-irrelevant flickering backgrounds was significantly enlarged when attention was focused upon the character sequence at the same location. This amplitude enhancement with attention was most prominent over occipital-temporal scalp areas of the right cerebral hemisphere regardless of the visual field of stimulation. These findings indicate that the SSVEP reflects an enhancement of neural responses to all stimuli that fall within the "spotlight" of spatial attention, whether or not the stimuli are task-relevant. Recordings of the SSVEP provide a new approach for studying the neural mechanisms and functional properties of selective attention to multi-element visual displays. PMID:8643478

  8. Pattern and motion-related visual-evoked potentials in neuroborreliosis: follow-up study.

    PubMed

    Szanyi, J; Kubová, Z; Kremláček, J; Langrová, J; Vít, F; Kuba, M; Szanyi, J; Plíšek, S

    2012-04-01

    Visual-evoked potentials (VEPs) were used for objective testing of visual functions during treatment courses of Lyme neuroborreliosis (LNB) in adult patients in the Czech Republic. In 30 LNB patients with originally delayed VEP latencies, pattern-reversal (R-VEP) and motion onset (M-VEP) VEPs were repeatedly examined within 1 to 8 years. Six patients had Lyme optic neuritis (ON), five of them displayed prolonged latencies in both R-VEPs and M-VEPs, and one had only abnormal R-VEPs. The VEP recovery to normal latency values was in three of them. In the group of 24 LNB patients without ON, 14 patients displayed prolonged latencies only to motion stimuli, and 10 patients had abnormal latencies in both R-VEPs and M-VEPs. During the follow-up period, 7 patients displayed shortening to normal latencies. In 5 patients, VEPs latencies improved only partially, and in the remaining 12 patients, VEPs did not improve at all. This study provides objective evidence that in LNB, most of the patients without clinically manifesting ON display optic pathway involvement-predominantly magnocellular system/dorsal stream function changes. In patients with ON, however, mainly the parvocellular system is affected. About half of the patients without ON improved with a relatively long-time course of latency shortening. PMID:22469684

  9. Spinal cord injury from electrocautery: observations in a porcine model using electromyography and motor evoked potentials.

    PubMed

    Skinner, Stanley A; Hsu, Brian; Transfeldt, Ensor E; Mehbod, Amir A; Rippe, David M; Wu, Chunhui; Erkan, Serkan

    2013-04-01

    We have previously investigated electromyographic (EMG) and transcranial motor evoked potential (MEP) abnormalities after mechanical spinal cord injury. We now report thermally generated porcine spinal cord injury, characterized by spinal cord generated hindlimb EMG injury activity and spinal cord motor conduction block (MEP loss). Electrocautery (EC) was delivered to thoracic level dural root sleeves within 6-8 mm of the spinal cord (n = 6). Temperature recordings were made near the spinal cord. EMG and MEP were recorded by multiple gluteobiceps intramuscular electrodes before, during, and after EC. Duration of EC was titrated to an end-point of spinal motor conduction block (MEP loss). In 5/6 roots, ipsilateral EMG injury activity was induced by EC. In 4/5 roots, EMG injury activity was identified before MEP loss. In all roots, a minimum of 20 s EC and a temperature maximum of at least 57 C at the dural root sleeve were required to induce MEP loss. Unexpectedly, conduction block was preceded by an enhanced MEP in 4/6 trials. EMG injury activity, preceding MEP loss, can be seen during near spinal cord EC. Depolarization and facilitation of lumbar motor neurons by thermally excited descending spinal tracts likely explains both hindlimb EMG and an enhanced MEP signal (seen before conduction block) respectively. A thermal mechanism may play a role in some unexplained MEP losses during intraoperative monitoring. EMG recordings might help to detect abnormal discharges and forewarn the monitorist during both mechanical and thermal injury to the spinal cord. PMID:23179021

  10. Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

    PubMed

    Huang, Bowan; Liang, Feixue; Zhong, Lei; Lin, Minlin; Yang, Juan; Yan, Linqing; Xiao, Jinfan; Xiao, Zhongju

    2015-01-01

    Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (?L and ?I) were extracted during anesthesia. ?L and ?I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ?L and ?I. However, ?L was changed by the hypothermia, whereas ?I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ?L monitors the effect of hypothermia on nerve fibers, and ?I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ?I monitors the anesthesia effect on synapses. PMID:26246365

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

    PubMed

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

    2013-03-01

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

  12. Downbeat nystagmus: evidence for enhancement of utriculo-ocular pathways by ocular vestibular evoked myogenic potentials?

    PubMed

    Bremova, Tatiana; Glasauer, Stefan; Strupp, Michael

    2015-11-01

    Downbeat nystagmus (DBN) is caused by an impairment of Purkinje cells in the flocculus. The decreased cerebellar inhibitory input affects otolith pathways. Since ocular and cervical vestibular evoked myogenic potentials (o-/cVEMP) test the otoliths, the VEMP were measured in DBN patients and in controls. Sixteen patients with DBN, 14 cerebellar oculomotor disorder patients without DBN (COMD), and 16 healthy controls were examined with o-/cVEMP. Computational modeling was used to predict VEMP differences between groups. DBN patients had significantly higher oVEMP peak-to-peak (PP) amplitudes than COMD patients without DBN and controls. Cervical VEMP did not differ. The computational model of DBN predicted a twofold oVEMP increase for DBN patients. These findings suggest an enhancement of the utriculo-ocular response. The unchanged cVEMP indicate no effect on the otolith-cervical reflex in DBN. Computational modeling suggests that the utriculo-ocular enhancement is caused by an impaired vertical neural integrator resulting in the increased influence of utricular signals. This also explains the gravitational dependence of DBN. PMID:26024694

  13. Pattern-Reversal Visual Evoked Potential Parameters and Migraine in the Teenage Population.

    PubMed

    Jancic, Jasna; Petrusic, Igor; Pavlovski, Vera; Savkovic, Zorica; Vucinic, Dragana; Martinovic, Zarko

    2016-05-01

    Although migraine represents one of the most common form of primary headache in the teenage population, most neurophysiologic studies are only on the adulthood. We investigated 38 teenage patients with migraine with aura, 17 male and 21 female, with a mean age of 16.2 years, comparing them with gender- and age-matched patients with migraine without aura and healthy subjects. Also, characteristics of aura were correlated with pattern-reversal visual evoked potential parameters. There was a significant difference in left and right eye N2 wave latencies between migraine with aura and migraine without aura patients or healthy controls. In migraine with aura and migraine without aura, 26.3% of patients had abnormal wave latency. Reported tunnel vision during the aura was correlated with lower N1P1 and/or P1N2 wave amplitudes. Also, higher amplitude in patients with migraine with aura correlated with younger age and earlier disease onset, whereas longer aura duration correlated with prolonged wave latency. Findings suggest that migraine subtypes may be differentiated on the basis of N2 wave latency prolongation. PMID:26542983

  14. Acute hypothyroidism leads to reversible alterations in central nervous system as revealed by somatosensory evoked potentials.

    PubMed

    Ozkardes, A; Ozata, M; Beyhan, Z; Corakci, A; Vural, O; Yardim, M; Gundogan, M A

    1996-11-01

    Although functional alterations in the central nervous system (CNS) and peripheral nerves are well documented in overt hypothyroidism, little is known about alterations of CNS in acute hypothyroidism. Sixteen patients with differentiated thyroid carcinoma were studied when prepared for radioiodine scanning after stopping levothyroxine (L-T4) therapy for 6 weeks to determine whether acute hypothyroidism leads to alteration in somatosensory evoked potentials (SSEPs). Repeat SSEPs were performed on the same patients at 6 months following L-T4 therapy when patients were euthyroid. Neurophysiological findings were compared with a group of 20 normal controls with no history of thyroid disease. Peripheral and central conduction in the median and tibial nerve stimulated SSEPs studied. A significant prolongation of central conduction time in SSEPs was found in patients with acute hypothyroidism when compared to those in control subjects. Abnormal latencies were not correlated with thyroid hormone levels. These neurophysiologic abnormalities were completely restored to normal at 6 months after L-T4 therapy. We conclude that acute hypothyroidism leads to reversible alterations in CNS as determined by SSEP recordings. Our results also suggest that SSEPs could be useful tests to monitor functional alteration of the CNS in acute hypothyroidism. PMID:8980414

  15. Visual Evoked Potential Response Among Drug Abusers- A Cross Sectional Study

    PubMed Central

    Sharma, Rajeev; Thapar, Satish; Mittal, Shilekh

    2016-01-01

    Introduction There is important preclinical evidence that substance abuse may produce neurophysiological disturbances particularly in relation to altered neural synchronization in Visual Evoked Potentials (VEP). Aim The purpose of current study was to compare the latencies and amplitudes of different waveforms of VEP among different drug abusers and controls and also to identify early neurological damage so that proper counseling and timely intervention can be undertaken. Materials and Methods VEP was assessed by Data Acquisition and Analysis system in a sample of 58 drug abusers, all males, within age group of 15-45 years as well as in age matched 30 healthy controls. The peak latencies and peak to peak amplitudes of different waveforms were measured by applying one-way Anova test and unpaired t-test using SPSS version 16. Results In between drug abusers and controls, the difference in the duration of N75 and P100 waveform of VEP was found to be statistically highly significant (p<0.001) in both the eyes. Also the amplitude of wave P100 was found to be decreased among drug abusers in both eyes. Conclusion Chronic intoxication by different drugs has been extensively associated with amplitude reduction of P100 and prolonged latency of N75 and P100 reflecting an adverse effects of drug dependence on neural transmission within primary visual areas of brain. PMID:27042456

  16. Regional Hypothermia Inhibits Spinal Cord Somatosensory-Evoked Potentials without Neural Damage in Uninjured Rats

    PubMed Central

    Li, Ning; Tian, Lei; Wu, Wei; Lu, Huchen; Zhou, Yuan; Xu, Xiaoyu; Zhang, Xiangsheng

    2013-01-01

    Abstract Both the therapeutic effects of regional hypothermia (RH) and somatosensory-evoked potentials (SSEP) have been intensively studied; however, the in vivo relationship between the two remains unknown. The primary focus of the current study was to investigate the impact of RH on SSEP in uninjured rats, as well as the neural safety of RH on neuronal health. An epidural perfusion model was used to keep local temperature steady by adjusting perfusion speed at 30°C, 26°C, 22°C, and 18°C for 30 min, respectively. Total hypothermic duration lasted up to 3 h. Neural signals were recorded at the end of each hypothermic period, as well as before cooling and after spontaneous rewarming. In addition, the Basso, Beattie, and Bresnahan (BBB) Locomotor Rating Scale was used to evaluate the effects of RH pre- and post-operative, combined with hematoxylin and eosin (H&E) and Fluoro-Jade C (FJC) staining. The results showed a marked declining trend in SSEP amplitude, as well as a significant prolongation in latency only during profound hypothermia (18°C). The BBB scale remained consistent at 21 throughout the entire process, signifying that no motor function injury was caused by RH. In addition, H&E and FJC staining did not show obvious histological injury. These findings firmly support the conclusion that RH, specifically profound RH, inhibits spinal cord SSEP in both amplitude and latency without neural damage in uninjured rats. PMID:22916828

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

    PubMed Central

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

    2013-01-01

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

  18. Extraction of steady state visually evoked potential signal and estimation of distribution map from EEG data.

    PubMed

    Washizawa, Yoshikazu; Yamashita, Yukihiko; Tanaka, Toshihisa; Cichocki, Andrzej

    2007-01-01

    We propose a signal extraction method from multi-channel EEG signals and apply to extract Steady State Visually Evoked Potential (SSVEP) signal. SSVEP is a response to visual stimuli presented in the form of flushing patterns. By using several flushing patterns with different frequency, brain machine (computer) interface (BMI/BCI) can be realized. Therefore it is important to extract SSVEP signals from multi-channel EEG signals. At first, we estimate the power of the objective signal in each electrode. Estimation of the power is helpful in not only extraction of the signal but also drawing a distribution map of the signal, finding electrodes which have large SNR, and ranking electrodes in sort of information with respect to the power of the signal. Experimental results show that the proposed method 1) estimates more accurate power than existing methods, 2) estimates the global signal which has larger SNR than existing methods, and 3) allows us to draw a distribution map of the signal, and it conforms the biological theory. PMID:18003244

  19. Factors affecting the stimulus artifact tail in surface-recorded somatosensory-evoked potentials.

    PubMed

    Hua, Y; Lovely, D F; Doraiswami, R

    2006-03-01

    Surface-recorded somatosensory-evoked potentials (SEPs) are neural signals elicited by an external stimulus. In the case of electrically induced SEPs, the artifact generated by the stimulation process can severely distort the signal. In some cases, the artifact tail often lasts well into the initiation of the SEP making the determination of absolute latency very difficult. In this work, a new approach was taken to identify factors that affect the tail of the artifact. The methodology adopted was the development of a lumped electrical circuit model of the artifact generation process. While the modeling of the instrumentation hardware is relatively simple, this is not the case with tissue and electrode/skin interface effects. Consequently, this paper describes a novel tissue modeling approach that uses an autoregressive moving average (ARMA) parametric technique and an artificial neural network (ANN) to estimate tissue parameters from experimental data. This coupled with an estimation of the stimulation electrode-skin impedance completes the lumped circuit model. Simulink (The Mathworks Inc.) was used to evaluate the model under several different conditions. These results show that both the stimulation electrode-skin interface impedance and nature of the body tissue directly under the recording electrodes have a profound effect on the appearance of the stimulus artifact tail. This was verified by experimentally recorded data obtained from the median nerve using surface electrodes. Conclusions drawn from this work include that stimulation electrodes with low series capacitance should be used whenever possible to minimize the duration of the artifact tail. PMID:16937164

  20. A steady state visually evoked potential investigation of memory and ageing.

    PubMed

    Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

    2009-04-01

    Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and latency associated with memory performance. Participants were 15 older (59-67 years) and 14 younger (20-30 years) adults who performed an object working memory (OWM) task and a contextual recognition memory (CRM) task, whilst the SSVEP was recorded from 64 electrode sites. Retention of a single object in the low demand OWM task was characterised by smaller frontal SSVEP amplitude and latency differences in older adults than in younger adults, indicative of an age-associated reduction in neural processes. Recognition of visual images in the more difficult CRM task was accompanied by larger, more sustained SSVEP amplitude and latency decreases over temporal parietal regions in older adults. In contrast, the more transient, frontally mediated pattern of activity demonstrated by younger adults suggests that younger and older adults utilize different neural resources to perform recognition judgements. The results provide support for compensatory processes in the aging brain; at lower task demands, older adults demonstrate reduced neural activity, whereas at greater task demands neural activity is increased. PMID:19135766

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

    PubMed

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

    2009-04-01

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

  2. The effect of pre and postnatal cadmium exposure on somatosensory evoked potentials: relation to lipid peroxidation.

    PubMed

    Agar, A; Yargiçoğlu, P; Izgüt-Uysal, V N; Sentürk, U K; Aktekin, B

    2000-01-01

    Pregnant swiss albino rats were divided into three groups: control (C), gestational exposure of cadmium (G-Cd) and gestational/postnatal exposure of cadmium (GP-Cd) groups. Control animals received tap water and the rats of GP-Cd group received Cd as CdCl2 in their drinking water during the experimental period. G-Cd group was given Cd during pregnancy, but given tap water after birth. Twenty-two days after birth, 15 rats (for each group) were taken from their mothers and continued to be treated with Cd (GP-Cd group) or tap water (C and G-Cd groups) for an additional 38 days. On postnatal day (PND) 60, somatosensory evoked potentials (SEPS) of three groups were recorded following left posterior tibial nerve (PTN) stimulation. The mean latencies of N1, P1, and N2, components were significantly prolonged in both Cd groups compared with control group. The mean latency of N1 in the GP-Cd group was longer than control and the G-Cd groups. There was no significant amplitude differences among groups. On the other hand, thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation, were increased in the sciatic nerves of both groups compared with control group. A significant increase in the TBARS level of the brain was found only in GP-Cd group due to significant accumulation of Cd. PMID:10765989

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

    PubMed

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

    2011-07-01

    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

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

    PubMed

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

    2011-01-01

    The aim of this study was to clarify the dose-dependent effect of sulfite (SO₃²⁻) 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, S₂; 100mg/kg/day, S₃; 260 mg/kg/day). Control rats were administered distilled water, while the other three groups were given sodium metabisulfite (Na₂S₂O₅) of amounts mentioned above, via gavage for a period of 35 days. All components of visual evoked potential (VEP) were prolonged in S₂ and S₃ groups compared with S₁ and C groups. Plasma-S-sulfonate levels, which are an indicator of sulfur dioxide (SO₂) exposure, were increased in Na₂S₂O₅ 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 Na₂S₂O₅. Though not significant, glutathione (GSH) and oxidized glutathione (GSSG) levels were observed to decrease with increasing doses of Na₂S₂O₅. In conclusion, Na₂S₂O₅ 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

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

    PubMed

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

    2009-01-01

    This study aimed to investigate the effect of alpha-lipoic acid (LA) administration on sulfite-induced alterations in visual evoked potentials (VEPs). Fifty two male albino Wistar rats were randomized into four experimental groups as follows; control (C), LA treated (L), sodium metabisulfite (Na(2)S(2)O(5)) treated (S), Na(2)S(2)O(5)+LA treated (SL). Na(2)S(2)O(5) (260 mg/kg/day) and LA (100 mg/kg/day) were given by intragastric intubation for 5 weeks. The latencies of VEP components were significantly prolonged in the S group and returned to control levels following LA administration. Thiobarbituric acid reactive substances (TBARS) levels in the S group were significantly higher than those detected in controls. LA significantly decreased brain and retina TBARS levels in the SL group compared with the S group. Sulfite caused a significant decrease in retina and brain glutathione peroxidase (GPx) activities which was restored to control levels via LA administration. Brain glutathione (GSH):glutathione disulfide (GSSG) ratio was significantly increased in rats jointly treated with sulfite and LA compared to rats treated with sulfite alone. Though not significant, a similar increase in GSH:GSSG ratio was also observed in the retina of SL group. This study showed that LA is protective against sulfite-induced VEP alterations and oxidative stress in the brain and retina. PMID:18761084

  6. [Usefulness and Problems of Intraoperative Monitoring for Unruptured Aneurysm Surgery with the Motor Evoked Potential].

    PubMed

    Ishizaki, Tomotaka; Endo, Otone; Fujii, Kentaro; Matsudaira, Tetsushi; Okada, Takeshi; Kobayashi, Nozomu; Kitamura, Michiko; Shibata, Makiko; Higuchi, Masaya; Hirano, Noriko; Furuichi, Chinari; Moroto, Akiyo; Mita, Maki; Shimizu, Takayuki; Yamamoto, Naohito

    2016-04-01

    It has been pointed out that the motor evoked potential(MEP)with a subdural electrode is useful in the intraoperative monitoring for unruptured aneurysm surgery. However, in some cases, we experienced postoperative ischemic complications despite evaluating the motor function via MEP monitoring. Herein, we have reported the usefulness and problems of intraoperative monitoring with MEP to evaluate brain dysfunction caused by insufficiency of cerebral blood flow. Out of 279 aneurysm surgery procedures, we performed MEP monitoring in 142 cases and successfully recorded in 126 cases. We compared the ischemic complication rate of the group for which MEP was monitored with that of the group for which MEP was not monitored. The whole ischemic complication rate was decreased in the group that underwent MEP monitoring. Thus, it was suggested that MEP monitoring was useful for avoiding ischemic complications. In internal carotid artery aneurysms, the amplitude of MEP changed and recovered in 2 cases and disappeared in one case. In anterior cerebral artery aneurysms, the amplitude of MEP changed and recovered in 2 cases. In middle cerebral artery aneurysms, the amplitude of MEP changed and recovered in 5 cases. We could avoid ischemic complications by intraoperative MEP monitoring in many cases. However, in some cases, we found ischemic complications that were not detected by MEP monitoring with a subdural electrode. In these cases, transcranial stimulation in combination with subdural electrode might be effective in avoiding ischemic complications that might occur after dural closure. PMID:27056869

  7. Eliciting steady-state visual evoked potentials by means of stereoscopic displays

    NASA Astrophysics Data System (ADS)

    Calore, Enrico; Gadia, Davide; Marini, Daniele

    2014-03-01

    Brain-Computer Interfaces (BCIs) provide users communication and control capabilities by analyzing their brain activity. A technique to implement BCIs, used recently also in Virtual Reality (VR) environments, is based on the Steady State Visual Evoked Potentials (SSVEPs) detection. Exploiting the SSVEP response, BCIs could be implemented showing targets flickering at different frequencies and detecting which is gazed by the observer analyzing her/his electroencephalographic (EEG) signals. In this work, we evaluate the use of stereoscopic displays for the presentation of SSVEP eliciting stimuli, comparing their effectiveness between monoscopic and stereoscopic stimuli. Moreover we propose a novel method to elicit SSVEP responses exploiting the stereoscopic displays capability of presenting dichoptic stimuli. We have created an experimental scene to present flickering stimuli on an active stereoscopic display, obtaining reliable control of the targets' frequency independently for the two stereo views. Using an EEG acquisition device, we analyzed the SSVEP responses from a group of subjects. From the preliminary results, we got evidence that stereoscopic displays represent valid devices for the presentation of SSVEP stimuli. Moreover, the use of different flickering frequencies for the two views of a single stimulus proved to elicit non-linear interactions between the stimulation frequencies, clearly visible in the EEG signal. This suggests interesting applications for SSVEP-based BCIs in VR environments able to overcome some limitations imposed by the refresh frequency of standard displays, but also the use of commodity stereoscopic displays to implement binocular rivalry experiments.

  8. Visual evoked potential correlates of laser flashblindness in rhesus monkeys. I. Argon laser flashes

    SciTech Connect

    Previc, F.H.; Blankenstein, M.F.; Garcia, P.V.; Allen, R.G.

    1985-05-01

    The visual evoked potential (VEP) in three rhesus monkeys was used to assess the transient loss of visual function resulting from single 100-msec argon laser flashes (514.5 nm), at energy levels well below the Maximum Permissible Exposure (MPE). VEPs were elicited by high-contrast squarewave test gratings phase reversed at a frequency of 6 Hz, and were recorded using bipolar electrodes implanted in the foveal projection region of area 17. The parameters which were investigated included: (a) flash size (focused vs. expanded); (b) position of the electrode's receptive field relative to the position of the flash (0, 1.5, 3.0 and 4.5/sup 0/ separation); (c) flash exposure level (50, 5 and 0.5 % of the MPE); (d) peak wavelength of the test grating (454, 540 and 630 nm); and (e) spatial frequency of the test grating (1.0, 4.0, 6.0 and 12.0 c/deg). The results of the flash size experiment revealed that the expanded flash (retinal diameter approx. 700 micrometers) eliminated or severely attenuated the VEP for a longer duration than did the focused flash, and also resulted in more gradual recovery function. In general, the findings suggest that the focused and expanded Argon laser flashes produce a VEP suppression whose time-course and other characteristics correlate highly with those associated with the flashblindness observed behaviorally in humans following exposure to intense noncoherent flashes.

  9. Interaction of Musicianship and Aging: A Comparison of Cortical Auditory Evoked Potentials

    PubMed Central

    O'Brien, Jennifer L.; Nikjeh, Dee A.; Lister, Jennifer J.

    2015-01-01

    Objective. The goal of this study was to begin to explore whether the beneficial auditory neural effects of early music training persist throughout life and influence age-related changes in neurophysiological processing of sound. Design. Cortical auditory evoked potentials (CAEPs) elicited by harmonic tone complexes were examined, including P1-N1-P2, mismatch negativity (MMN), and P3a. Study Sample. Data from older adult musicians (n = 8) and nonmusicians (n = 8) (ages 55–70 years) were compared to previous data from young adult musicians (n = 40) and nonmusicians (n = 20) (ages 18–33 years). Results. P1-N1-P2 amplitudes and latencies did not differ between older adult musicians and nonmusicians; however, MMN and P3a latencies for harmonic tone deviances were earlier for older musicians than older nonmusicians. Comparisons of P1-N1-P2, MMN, and P3a components between older and young adult musicians and nonmusicians suggest that P1 and P2 latencies are significantly affected by age, but not musicianship, while MMN and P3a appear to be more sensitive to effects of musicianship than aging. Conclusions. Findings support beneficial influences of musicianship on central auditory function and suggest a positive interaction between aging and musicianship on the auditory neural system. PMID:26504354

  10. Short-term food deprivation increases amplitudes of heartbeat-evoked potentials.

    PubMed

    Schulz, André; Ferreira de Sá, Diana S; Dierolf, Angelika M; Lutz, Annika; van Dyck, Zoé; Vögele, Claus; Schächinger, Hartmut

    2015-05-01

    Nutritional state (i.e., fasting or nonfasting) may affect the processing of interoceptive signals, but mechanisms underlying this effect remain unclear. We investigated 16 healthy women on two separate days: when satiated (standardized food intake) and after an 18-h food deprivation period. On both days, heartbeat-evoked potentials (HEPs) and cardiac and autonomic nervous system activation indices (heart rate, normalized low frequency heart rate variability [nLF HRV]) were assessed. The HEP is an EEG pattern that is considered an index of cortical representation of afferent cardiovascular signals. Average HEP activity (R wave +455-595 ms) was enhanced during food deprivation compared to normal food intake. Cardiac activation did not differ between nutritional conditions. Our results indicate that short-term food deprivation amplifies an electrophysiological correlate of the cortical representation of visceral-afferent signals originating from the cardiovascular system. This effect could not be attributed to increased cardiac activation, as estimated by heart rate and nLF HRV, after food deprivation. PMID:25431244

  11. Dolphin hearing during echolocation: evoked potential responses in an Atlantic bottlenose dolphin (Tursiops truncatus).

    PubMed

    Li, Songhai; Nachtigall, Paul E; Breese, Marlee

    2011-06-15

    Auditory evoked potential (AEP) responses were recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by echolocation. AEP recording was triggered by the echolocation clicks of the animal. Three targets with target strengths of -34, -28 and -22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both outgoing echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of -22 and -28 dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5 logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system. PMID:21613519

  12. Evoked potentials to auditory probes as indices of cerebral specialization of function--replication and extension.

    PubMed

    Shucard, D W; Cummins, K R; Thomas, D G; Shucard, J L

    1981-11-01

    This study was an attempt to replicate findings from previous work in our laboratory as well as to study the relationship between vertex-referenced and linked mastoid-referenced responses under conditions purported to produce differential hemispheric activation. Auditory evoked potentials were recorded between T4-Cz, T3-Cz, T4-A1A2, and T3-A1A2 to task-irrelevant tone pips superimposed on a baseline condition and on two experimental conditions (verbal and music) hypothesized to differentially activate areas of the left and right cerebral hemispheres. Significant AEP amplitude asymmetries were obtained as a function of the ongoing tasks, replicating our previous findings. Higher amplitude AEPs were recorded from temporal-to-vertex leads from the hemisphere thought to be most involved in the ongoing task. In addition, temporal-linked mastoids placements showed an effect opposite to that seen for the vertex-referenced leads with lower amplitude AEPs occurring from the hemisphere purported to be most activated by the task. Mastoid-referenced placements were also less sensitive to task effects than vertex-referenced placements. PMID:6171402

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

    PubMed Central

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

    2014-01-01

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

  14. EEG-based classification of video quality perception using steady state visual evoked potentials (SSVEPs)

    NASA Astrophysics Data System (ADS)

    Acqualagna, Laura; Bosse, Sebastian; Porbadnigk, Anne K.; Curio, Gabriel; Müller, Klaus-Robert; Wiegand, Thomas; Blankertz, Benjamin

    2015-04-01

    Objective. Recent studies exploit the neural signal recorded via electroencephalography (EEG) to get a more objective measurement of perceived video quality. Most of these studies capitalize on the event-related potential component P3. We follow an alternative approach to the measurement problem investigating steady state visual evoked potentials (SSVEPs) as EEG correlates of quality changes. Unlike the P3, SSVEPs are directly linked to the sensory processing of the stimuli and do not require long experimental sessions to get a sufficient signal-to-noise ratio. Furthermore, we investigate the correlation of the EEG-based measures with the outcome of the standard behavioral assessment. Approach. As stimulus material, we used six gray-level natural images in six levels of degradation that were created by coding the images with the HM10.0 test model of the high efficiency video coding (H.265/MPEG-HEVC) using six different compression rates. The degraded images were presented in rapid alternation with the original images. In this setting, the presence of SSVEPs is a neural marker that objectively indicates the neural processing of the quality changes that are induced by the video coding. We tested two different machine learning methods to classify such potentials based on the modulation of the brain rhythm and on time-locked components, respectively. Main results. Results show high accuracies in classification of the neural signal over the threshold of the perception of the quality changes. Accuracies significantly correlate with the mean opinion scores given by the participants in the standardized degradation category rating quality assessment of the same group of images. Significance. The results show that neural assessment of video quality based on SSVEPs is a viable complement of the behavioral one and a significantly fast alternative to methods based on the P3 component.

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

    PubMed

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

    2015-09-01

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

  16. [A Case of Brainstem Cavernous Hemangioma Showing False Positive Response to Electromyographic Tracheal Tube].

    PubMed

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

    2015-08-01

    Brainstem cavernous hemangioma is a complex lesion associated with hemorrhage and neurological deficit. The damage of the vagus nerve is a devastating surgical complication. Therefore, intraoperative anatomical and functional evaluation of this nerve is crucial. We used electromyographic tracheal tube (EMG tube)to monitor electromyogram from the vocal cord. We report a case of brainstem cavernous hemangioma showing false positive response to EMG tube. A 66-year-old woman underwent resection of cavernous hemangioma in the pontine tegmentum. General anesthesia was induced with remifentanl, propofol, and suxamethonium, and was maintained with oxygen, air, remifentanil and propofol. We monitored somatosensory evoked potentials, motor evoked potentials, and electromyogram of the vocal cord, orbicularis oculi, orbicularis oris and lateral rectus. When the manipulation reached brainstem, slight spontaneous respiration (SR) appeared on capnogram. Simultaneously, an alarm rang. Exposed nerves were stimulated electrically. However, there was no electromyographic response on the vocal cord. We concluded that the cause was SR accompanied by vocal cord movement. Remifentanil was increased up to 1 μg x kg(-1) x min(-1). SR did not disappear. Remifentanil was not increased any more without hindering the operation. Her operative course was uneventful. It is necessary to pay attention to false positive response caused by SR with EMG tube. PMID:26442411

  17. Auditory evoked potential modifications according to clinical and biochemical responsiveness to fenfluramine treatment in children with autistic behavior.

    PubMed

    Bruneau, N; Barthélémy, C; Roux, S; Jouve, J; Lelord, G

    1989-01-01

    Evoked potentials to auditory stimulations varying in intensity were studied in 13 children with autistic behavior treated with fenfluramine. Modifications of both amplitude and single-trial potential variability were considered according to the clinical and biochemical responsiveness to this drug. Six children (responders) were clinically improved by the treatment. Electrophysiological data were affected according to the clinical and biochemical responsiveness to fenfluramine: the auditory evoked potential amplitude increased, and the single-trial potential variability decreased at each intensity level only in responders whose dopaminergic metabolism was significantly modified by fenfluramine treatment. No modification was found in nonresponders. Both biochemical and electrophysiological results argued for an amphetamine-like action of fenfluramine in those autistic children whose attention deficits are associated with motor disturbances including hyperactivity. PMID:2682347

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

    PubMed Central

    Huang, Shiliang; Du, Fang; Shih, Yen-Yu I.; Shen, Qiang; Gonzalez-Lima, F.; Duong, Timothy Q.

    2013-01-01

    Methylene blue USP (MB) at low doses has metabolic-enhancing and antioxidant properties and exhibits experimental neurotherapeutic benefits, but little is known about its in vivo effects on cerebral blood flow (CBF), functional evoked responses, and the associated changes in cerebral metabolic rate of oxygen consumption (CMRO2). This study used magnetic resonance imaging (MRI) to evaluate the in vivo effects of a single intravenous MB therapeutic dose (0.5 mg/kg) on basal CBF, blood oxygenation level-dependent (BOLD) and CBF responses to hypercapnic (5% CO2 in air) inhalation, as well as changes in BOLD, CBF, and CMRO2 during forepaw stimulation in the rat brain. We found that this MB therapeutic dose did not have significant effects on arterial oxygen saturation, heart rate and fMRI responses to hypercapnia. However, MB significantly potentiated forepaw-evoked BOLD and CBF changes under normoxia. To further evaluate in vivo effects of MB under metabolic stress conditions, MRI measurements were also made under mild hypoxia (15% O2). Hypoxia per se increased evoked functional MRI responses. MB under hypoxia further potentiated forepaw-evoked BOLD, CBF and oxygen consumption responses relative to normoxia. These findings provide insights into MB’s effects on cerebral hemodynamics in vivo and could help to optimize treatments in neurological diseases with mitochondrial dysfunction and oxidative stress. PMID:23357077

  19. Research on steady-state visual evoked potentials in 3D displays

    NASA Astrophysics Data System (ADS)

    Chien, Yu-Yi; Lee, Chia-Ying; Lin, Fang-Cheng; Huang, Yi-Pai; Ko, Li-Wei; Shieh, Han-Ping D.

    2015-05-01

    Brain-computer interfaces (BCIs) are intuitive systems for users to communicate with outer electronic devices. Steady state visual evoked potential (SSVEP) is one of the common inputs for BCI systems due to its easy detection and high information transfer rates. An advanced interactive platform integrated with liquid crystal displays is leading a trend to provide an alternative option not only for the handicapped but also for the public to make our lives more convenient. Many SSVEP-based BCI systems have been studied in a 2D environment; however there is only little literature about SSVEP-based BCI systems using 3D stimuli. 3D displays have potentials in SSVEP-based BCI systems because they can offer vivid images, good quality in presentation, various stimuli and more entertainment. The purpose of this study was to investigate the effect of two important 3D factors (disparity and crosstalk) on SSVEPs. Twelve participants participated in the experiment with a patterned retarder 3D display. The results show that there is a significant difference (p-value<0.05) between large and small disparity angle, and the signal-to-noise ratios (SNRs) of small disparity angles is higher than those of large disparity angles. The 3D stimuli with smaller disparity and lower crosstalk are more suitable for applications based on the results of 3D perception and SSVEP responses (SNR). Furthermore, we can infer the 3D perception of users by SSVEP responses, and modify the proper disparity of 3D images automatically in the future.

  20. Application of multifocal visual evoked potentials in the assessment of visual dysfunction in macular diseases

    PubMed Central

    Jiang, L; Zhang, H; Xie, J; Jiao, X; Zhou, H; Ji, H; Lai, T Y Y; Wang, N

    2011-01-01

    Purpose To evaluate the use of AccuMap multifocal visual evoked potentials (mfVEP) in visual dysfunction caused by macular diseases. Methods Forty-eight eyes with known macular diseases underwent AccuMap mfVEP and microperimetry 1 (MP1) assessments. Evaluation of mfVEP abnormality was based on an amplitude deviation probability plot and the AccuMap Severity Index (ASI). Correlation analyses of the mean mfVEP amplitude corresponding to a radius of 2, 5, and 10 of the central visual field, minimum angle of resolution best-corrected visual acuity (BCVA), and MP1 mean sensitivity of the corresponding areas were performed. Results Among the 48 affected eyes, AccuMap mfVEP detected an abnormality of the central visual field in 45 eyes, with a sensitivity of 93.8%. The mean mfVEP amplitudes within a radius of 2, 5, and 10 of the central visual field were found to be positively correlated with BCVA (P<0.01 for all groups). The mean amplitudes also positively correlated with the MP1 mean sensitivity value of the corresponding visual field (P<0.01 for all groups). In the group with stable fixation or predominantly central fixation, the mean mfVEP amplitudes did not correlate with the BCVA or the MP1 mean sensitivity value. Regardless of the fixation status, the ASI was found to correlate with both the BCVA and the total MP1 mean defect value. Conclusion Objective perimetry using AccuMap mfVEP might be applied in the assessment of macular function, with the ASI offering a potentially useful indicator for evaluating macular dysfunction. PMID:21720415

  1. Characterizing the time course of an implicature: an evoked potentials study.

    PubMed

    Noveck, Ira A; Posada, Andres

    2003-05-01

    This work employs Evoked Potential techniques as 19 participants are confronted with sentences that have the potential to produce scalar implicatures, like in Some elephants have trunks. Such an Underinformative utterance is of interest to pragmatists because it can be considered to have two different truth values. It can be considered true when taken at face value but false if one were to treat Some with the implicature Not All. Two accounts of implicature production are compared. The neo-Gricean approach (e.g., Levinson, 2000) assumes that implicatures intrude automatically on the semantics of a term like Some. Relevance Theory (Sperber & Wilson, 1985/1996) assumes that implicatures are effortful and not automatic. In this experiment, the participants are presented with 25 Underinformative sentences along with 25 sentences that are Patently True (e.g. Some houses have bricks) and 25 that are Patently False (e.g. Some crows have radios). As reported in an earlier study (Noveck, 2001), Underinformative sentences prompt strong individual differences. Seven participants here responded true to all (or nearly all) of the Underinformative sentences and the remaining 12 responded false to all (or nearly all) of them. The present study showed that those who responded false to the Underinformative sentences took significantly longer to do so that those who responded true. The ERP data indicate that: (a) the Patently True and Patently False sentences prompt steeper N400's--indicating greater semantic integration--than the Underinformative sentences and that (b) regardless of one's ultimate response to the Underinformative sentences, the N400's were remarkably flat, indicating no particular reaction to these sentences. Collectively, the data are taken to show that implicatures are part of a late-arriving, effort-demanding decision process. PMID:12735938

  2. Characterizing pinprick-evoked brain potentials before and after experimentally induced secondary hyperalgesia.

    PubMed

    van den Broeke, Emanuel N; Mouraux, André; Groneberg, Antonia H; Pfau, Doreen B; Treede, Rolf-Detlef; Klein, Thomas

    2015-11-01

    Secondary hyperalgesia is believed to be a key feature of "central sensitization" and is characterized by enhanced pain to mechanical nociceptive stimuli. The aim of the present study was to characterize, using EEG, the effects of pinprick stimulation intensity on the magnitude of pinprick-elicited brain potentials [event-related potentials (ERPs)] before and after secondary hyperalgesia induced by intradermal capsaicin in humans. Pinprick-elicited ERPs and pinprick-evoked pain ratings were recorded in 19 healthy volunteers, with mechanical pinprick stimuli of varying intensities (0.25-mm probe applied with a force extending between 16 and 512 mN). The recordings were performed before (T0) and 30 min after (T1) intradermal capsaicin injection. The contralateral noninjected arm served as control. ERPs elicited by stimulation of untreated skin were characterized by 1) an early-latency negative-positive complex peaking between 120 and 250 ms after stimulus onset (N120-P240) and maximal at the vertex and 2) a long-lasting positive wave peaking 400-600 ms after stimulus onset and maximal more posterior (P500), which was correlated to perceived pinprick pain. After capsaicin injection, pinprick stimuli were perceived as more intense in the area of secondary hyperalgesia and this effect was stronger for lower compared with higher stimulus intensities. In addition, there was an enhancement of the P500 elicited by stimuli of intermediate intensity, which was significant for 64 mN. The other components of the ERPs were unaffected by capsaicin. Our results suggest that the increase in P500 magnitude after capsaicin is mediated by facilitated mechanical nociceptive pathways. PMID:26334010

  3. Effects of flurbiprofen enantiomers on pain-related chemo-somatosensory evoked potentials in human subjects.

    PubMed Central

    Lötsch, J; Geisslinger, G; Mohammadian, P; Brune, K; Kobal, G

    1995-01-01

    1. The aim of the study was to investigate the analgesic effects of flurbiprofen enantiomers using an experimental pain model based on both chemo-somatosensory event-related potentials (CSSERP) and subjective pain ratings. 2. Healthy female volunteers (n = 16, age 23-36 years) participated in a placebo-controlled, randomised, double-blind, four-way crossover study. Single doses of (S)-flurbiprofen (50 mg), (R)-flurbiprofen (50 and 100 mg) and placebo were administered orally. Measurements were taken before and 2 h after administration of the medications. During each measurement, 32 painful stimuli of gaseous carbon dioxide (200 ms duration, interval approximately 30 s) of two concentrations (60 and 65% CO2 v/v) were applied to the right nostril. EEG was recorded from five positions and CSSERP were obtained in response to the painful CO2- stimuli. Additionally, subjects rated the perceived intensity of the painful stimuli by means of a visual analogue scale (VAS). 3. The CSSERP-amplitude P2, a measure of analgesic effect, decreased after administration of both (R)- and (S)-flurbiprofen, while it increased after placebo. This was statistically significant at recording positions C4 (P < 0.01) and Fz (P < 0.05). The analgesia-related decreases in evoked potential produced by (R)-flurbiprofen were dose-dependent. Comparing similar doses of (R)- and (S)-flurbiprofen, the decrease in CSSERP-amplitudes produced by the (S)-enantiomer was somewhat more pronounced, indicating a higher analgesic potency. 4. The present data indicate that both enantiomers of flurbiprofen produce analgesic effects. Since (R)-flurbiprofen caused only little toxicity in rats as compared with the (S)-enantiomer or the racemic compound, a reduction of the quantitatively most important side effects in the gastrointestinal tract might be achieved by employing (R)-flurbiprofen in pain therapy. PMID:8554936

  4. Specificity and sensitivity of visual evoked potentials in the diagnosis of schizophrenia: rethinking VEPs.

    PubMed

    González-Hernández, J A; Pita-Alcorta, C; Wolters, C H; Padrón, A; Finalé, A; Galán-García, L; Marot, M; Lencer, R

    2015-08-01

    Alterations of the visual evoked potential (VEP) component P1 at the occipital region represent the most extended functional references of early visual dysfunctions in schizophrenia (SZ). However, P1 deficits are not reliable enough to be accepted as standard susceptibility markers for use in clinical psychiatry. We have previously reported a novel approach combining a standard checkerboard pattern-reversal stimulus, spectral resolution VEP, source detection techniques and statistical procedures which allowed the correct classification of all patients as SZ compared to controls. Here, we applied the same statistical approach but to a single surface VEP - in contrast to the complex EEG source analyses in our previous report. P1 and N1 amplitude differences among spectral resolution VEPs from a POz-F3 bipolar montage were computed for each component. The resulting F-values were then Z-transformed. Individual comparisons of each component of P1 and N1 showed that in 72% of patients, their individual Z-score deviated from the normal distribution of controls for at least one of the two components. Crossvalidation against the distribution in the SZ-group improved the detection rate to 93%. In all, six patients were misclassified. Clinical validation yielded striking positive (78.13%) and negative (92.69%) predictive values. The here presented procedure offers a potential clinical screening method for increased susceptibility to SZ which should then be followed by high density electrode array and source detection analyses. The most important aspect of this work is represented by the fact that this diagnostic technique is low-cost and involves equipment that is feasible to use in typical community clinics. PMID:26004691

  5. An electrophysiological study of the accessory olfactory bulb in the rabbit--I. Analysis of electrically evoked potential fields.

    PubMed

    MacLeod, N K; Reinhardt, W

    1983-09-01

    Following electrical stimulation of the vomeronasal nerves, the primary olfactory nerves, the lateral olfactory tract and the corticomedial amygdala, we have made a study of evoked potentials in the rabbit accessory olfactory bulb. Vomeronasal nerve stimulation evoked a complex field potential consisting of a compound action potential followed by 4 negative waves (N1, N2, N3, N4). In contrast to the field potential elicited in the main olfactory bulb following primary olfactory nerve stimulation, there was either no evoked wave or only a weak positive component of the field in the accessory bulb. Amygdala stimulation caused a long latency, long duration negative-positive dipolar field potential in the accessory olfactory bulb. Both antidromic and orthodromic field potentials showed sign reversal when the electrode penetrated the bulb at a point corresponding to the lower border of the mitral cell band. Stimulation of the lateral olfactory tract elicited a weak, short-latency wave which did not show any sign reversal when the electrode was lowered into the accessory bulb. This wave was presumably due to fibres arising in the main bulb and projecting through the accessory bulb into the lateral olfactory tract. Electrical stimulation of the primary olfactory nerves did not induce any response in the accessory bulb neither did vomeronasal nerve stimulation evoke a response in the main olfactory bulb. The origin of these potential fields is discussed and it is concluded that the synaptic organization of the accessory olfactory bulb resembles that of the main olfactory bulb in lower vertebrates. There is no detectable communication between the two olfactory systems. PMID:6646418

  6. Focal brainstem gliomas

    PubMed Central

    Sabbagh, Abdulrahman J.; Alaqeel, Ahmed M.

    2015-01-01

    Improved neuronavigation guidance as well as intraoperative imaging and neurophysiologic monitoring technologies have enhanced the ability of neurosurgeons to resect focal brainstem gliomas. In contrast, diffuse brainstem gliomas are considered to be inoperable lesions. This article is a continuation of an article that discussed brainstem glioma diagnostics, imaging, and classification. Here, we address open surgical treatment of and approaches to focal, dorsally exophytic, and cervicomedullary brainstem gliomas. Intraoperative neuronavigation, intraoperative neurophysiologic monitoring, as well as intraoperative imaging are discussed as adjunctive measures to help render these procedures safer, more acute, and closer to achieving surgical goals. PMID:25864061

  7. Compensation of intraoperative transcranial motor-evoked potential monitoring by compound muscle action potential after peripheral nerve stimulation.

    PubMed

    Tanaka, Satoshi; Kobayashi, Ikuo; Sagiuchi, Takao; Takanashi, Junko; Iwamoto, Kazuhisa; Sato, Sumito; Fujii, Kiyotaka

    2005-08-01

    It is often difficult to evaluate the results of transcranial motor-evoked potential (TCMEP) monitoring in patients under general anesthesia because these results are strongly affected by anesthetics and muscle relaxants. To exclude effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supramaximum stimulation of the median nerve immediately after transcranial stimulation (300 to 600 V) was recorded in 70 neurosurgical operations. A relative amplitude index (RAI) was defined as the amplitude of TCMEP after the operative procedure divided by the amplitude of TCMEP before the operative procedure. The RAI was calculated and was compensated by the amplitude of CMAP in 141 limbs. In 12 limbs of 7 patients with postoperatively progressed motor paresis, the compensated RAI was less than 0.2. The compensated RAI in all other 129 limbs of 63 patients without postoperative motor palsy was more than 0.2. These results suggest that compensation of TCMEP monitoring by CMAP is an easy and accurate method for removing the effects of muscle relaxants in TCMEP. PMID:16093899

  8. Influence of dopamine on flash visual evoked potentials (FVEP) in prenatally mercury intoxicated rats.

    PubMed

    Herba, Ewa; Pojda-Wilczek, Dorota; Plech, Agata R; Pojda, Stefan M; Szkilnik, Ryszard

    2004-01-01

    The female adult white Wistar rats were given tap water (control) or 50 ppm of methylmercury chloride (MMC) ad libitum throughout their pregnancies. Newborn rats drank mother's milk during the first 21 days after delivery and then only tap water. The study was carried out on three-month old offsprings of white Wistar rats. The flash visual evoked potentials (FVEP) were recorded before and after injecting of 10 microl 0.9% saline, 50 or 100 nmols of dopamine (DA) into the lateral brain ventricle by method used before in our laboratory. The amplitude of the first deep negative (N(1)) peak significantly increased to 109-114% after both doses of DA in the control group and to 138-139% in mercury-treated animals. The amplitude of the next positive (P(1)) wave decreased to 94% and 86% in the control group after 50 and 100 nmols of DA, respectively. In Hg-treated group after 50 nmols of DA, the value dropped down to 91%, but increased to 109% after 100 nmols of DA. The increasing of DeltaN(1)P(1) was observed in the control group to 112% after 50 nmols and to 109% after 100 nmols of DA and in Hg-exposed rats, respectively, to 127% and to 129%. The described changes were statistically significant (p < 0.05). The N(1) and P(1) latencies were prolonged in the control group after both doses of DA. In Hg-treated group, the prolongation of N(1) latency was recorded, while the P(1) latency was not changed. We concluded that prenatal Hg intoxication disturbed the effect of DA on FVEP. PMID:15520495

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

    PubMed Central

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

    2016-01-01

    Previous functional Magnetic Resonance Imaging studies evaluated the role of satiety on cortical taste area activity and highlighted decreased activation in the orbito-frontal cortex when food was eaten until satiation. The modulation of orbito-frontal neurons (secondary taste area) by ad libitum food intake has been associated with the pleasantness of the food's flavor. The insula and frontal operculum (primary taste area) are also involved in reward processing. The aim was to compare human gustatory evoked potentials (GEP) recorded in the primary and secondary gustatory cortices in a fasted state with those after food intake. Fifteen healthy volunteers were enrolled in this observational study. In each of two sessions, two GEP recordings were performed (at 11:00 am and 1:30 pm) in response to sucrose gustatory stimulation, and a sucrose-gustatory threshold was determined. During one session, a standard lunch was provided between the two GEP recordings. During the other session, subjects had nothing to eat. Hunger sensation, wanting, liking, and the perception of the solution's intensity were evaluated with visual analog scales. GEP latencies measured in the Pz (p < 0.001), Cz (p < 0.01), Fz (p < 0.001) recordings (primary taste area) were longer after lunch than in the pre-prandial condition. Fp1 and Fp2 latencies (secondary taste area) tended to be longer after lunch, but the difference was not significant. No difference was observed for the sucrose-gustatory threshold regardless of the session and time. Modifications in the primary taste area activity during the post-prandial period occurred regardless of the nature of the food eaten and could represent the activity of the frontal operculum and insula, which was recently shown to be modulated by gut signals (GLP-1, CCK, ghrelin, or insulin) through vagal afferent neurons or metabolic changes of the internal milieu after nutrient absorption. This trial was registered at clinicalstrials.gov as NCT02472444. PMID:26778949

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2004-06-01

    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) in biceps brachii and first dorsal interosseus muscles were measured at 2-min intervals before and after exercise. In another experiment, subjects performed exhaustive curls and, in addition to MEP areas, force production in biceps, hand-grip force, simple reaction times and movement times were measured bilaterally. MEPs were depressed after exhaustive exercise in the exercising biceps for over 60 min; depression was also observed 10-15 min after exercise in the non-exercising biceps but not in the first dorsal interosseus of either hand. The shorter exercise period produced depression of MEPs only in the exercising muscle. After exhaustive exercise maximum voluntary contraction fell in the exercising biceps and this correlated with MEP areas. No reduction in force was seen in the non-exercising biceps but hand-grip force fell slightly in both arms. There was no change in reaction times or movement times. Depression of MEPs can occur in non-exercising homonymous muscles but not in heteronymous muscles and only when exercise levels are high. There was no measurable functional deficit in the non-exercising limb, so we conclude that the reduced corticospinal excitability observed in this limb has little or no consequence on the performance parameters measured. PMID:15045505

  12. Motor-evoked potentials reveal a motor-cortical readout of evidence accumulation for sensorimotor decisions.

    PubMed

    Yarrow, Kielan; Hadar, Aviad; Rowe, Paula; Di Costa, Steven; Jones, Alex

    2015-01-01

    Many everyday activities, such as driving and sports, require us to engage in time-pressured sensorimotor decision making in response to visual cues. The computational principle of continuous evidence accumulation is the dominant account underlying models of speeded decision making, but the nature and locus of the decision variable that triggers action is debated. Traditionally, cognitive stages such as perception, stimulus-response translation, and the generation of motor plans, have been considered to occur in series. However, this idea is challenged by neurophysiological work in animals, suggesting that cognitive operations are distributed across sensorimotor cortex. Here, we investigate whether a decision variable can be observed in the primary motor cortex (M1) of humans. Participants categorised faces as male or female, with task difficulty manipulated using natural or morphed stimuli. Transcranial magnetic stimulation, applied at random across the reaction-time interval, produced motor-evoked potentials (MEPs) in two hand muscles that were the major contributors when generating the correct and incorrect pinch/grip movements. MEP magnitudes reveal covert action preparation, even when no action is produced. Smoothing MEPs using a Gaussian kernel allowed us to recover a continuous time-varying MEP average, comparable to an EEG component, which permitted precise localisation of the time at which the motor plan for the responding muscle began to dominate over the non-responding action. This moment was calculated in both stimulus-locked and response-locked analyses, and was found to occur at the same time with stimulus locking, but earlier with response locking, when ambiguous stimuli made the decision more challenging. This pattern is consistent with M1 providing a continuous readout of evidence accumulation. We predicted the evidence accumulation profile from a drift diffusion model, using only behavioural data, and found a good qualitative match to the observed neurometric MEP profiles. Meeting abstract presented at VSS 2015. PMID:26325737

  13. Effect of sevoflurane concentration on visual evoked potentials with pattern stimulation in dogs.

    PubMed

    Ito, Yosuke; Maehara, Seiya; Itoh, Yoshiki; Hayashi, Miri; Kubo, Akira; Itami, Takaharu; Ishizuka, Tomohito; Tamura, Jun; Yamashita, Kazuto

    2015-02-01

    The purpose of this study was to investigate the effects of sevoflurane concentration on canine visual evoked potentials with pattern stimulation (P-VEPs). Six clinically normal laboratory-beagle dogs were used. The minimum alveolar concentration (MAC) of sevoflurane was detected from all subjects by tail clamp method. The refractive power of the right eyes of all subjects was corrected to -2 diopters after skiascopy. For P-VEP recording, the recording and reference electrode were positioned at inion and nasion, respectively, and the earth electrode was positioned on the inner surface. To grasp the state of CNS suppression objectively, the bispectral index (BIS) value was used. The stimulus pattern size and distance for VEP recording were constant, 50.3 arc-min and 50 cm, respectively. P-VEPs and BIS values were recorded under sevoflurane in oxygen inhalational anesthesia at 0.5, 1.0, 1.5, 2.0, 2.5 and 2.75 sevoflurane MAC. For analysis of P-VEP, the P100 implicit time and N75-P100 amplitude were estimated. P-VEPs were detected at 0.5 to 1.5 MAC in all dogs, and disappeared at 2.0 MAC in four dogs and at 2.5 and 2.75 MAC in one dog each. The BIS value decreased with increasing sevoflurane MAC, and burst suppression began to appear from 1.5 MAC. There was no significant change in P100 implicit time and N75-P100 amplitude with any concentration of sevoflurane. At concentrations around 1.5 MAC, which are used routinely to immobilize dogs, sevoflurane showed no effect on P-VEP. PMID:25373729

  14. Characterization of Graded MASCIS Contusion Spinal Cord Injury using Somatosensory Evoked Potentials

    PubMed Central

    Agrawal, Gracee; Kerr, Candace; Thakor, Nitish V.; All, Angelo H.

    2009-01-01

    Study Design Electrophysiological analysis using somatosensory evoked potentials (SEPs) and behavioral assessment using Basso-Beattie-Bresnahan (BBB) scale were compared over time for graded MASCIS contusion spinal cord injury (SCI). Objective To study SEP responses across different contusion injury severities and to compare them with BBB scores. Summary of Background Data For any SCI therapy evaluation, it is important to accurately and objectively standardize the injury model. The graded MASCIS contusion injuries on dorsal spine have been standardized using BBB, which is subjective and prone to human errors. Furthermore, dorsal pathway disruption does not always produce locomotor deficits. SEP monitoring provides an advantage of providing a reliable and objective assessment of the functional integrity of dorsal sensory pathways. Methods Four groups of Fischer rats received contusion at T8 using NYU-MASCIS impactor from impact heights of 6.25 (mild), 12.5 (moderate), 25 (severe), or 50 mm (very severe). The control group underwent laminectomy only. SEP and BBB recordings were performed once prior to injury, and then weekly for up to 7 weeks. Results Graded levels of injury produced concomitant attenuations in hindlimb SEP amplitudes. Following injury, 25 and 50 mm groups together differed significantly from 12.5 and 6.25 mm groups (p<0.01). From week 5, differences between 12.5 and 6.25 mm groups also became apparent (p<0.01), which showed significant electrophysiological improvement. However, no significant differences were observed between 25 and 50 mm groups, which showed negligible electrophysiological recovery. While comparable differences between different groups were also detected by BBB after injury (p<0.001), BBB was less sensitive in detecting any improvement in 6.25 and 12.5 mm groups. Conclusion SEP amplitudes and BBB scores decrease corresponding to increase in injury severity, however these show different temporal patterns of recovery. These results demonstrate the utility of SEPs, in conjunction with BBB, to monitor therapeutic interventions in SCI research. PMID:20354478

  15. Optical coherence tomography versus visual evoked potential in multiple sclerosis patients

    PubMed Central

    Fatehi, Farzad; Mehr, Lida Kiani; Dehghani, Alireza

    2012-01-01

    Background Optical coherence tomography (OCT) is a non-invasive instrument, which can be used to estimate the thickness of the retinal nerve fibre layer (RNFL) and provides an indirect measurement of axonal destruction in multiple sclerosis (MS). The main aim of this study was to find out any correlations between P100 latency in visual evoked potential (VEP) and RNFL thickness. Methods The patients with the definite history of optic neuritis regardless of the diagnosis of MS were included. The eyes with the history of blurred vision and increased VEP latency (> 115 milliseconds) were considered as cases and the eyes with normal latency were regarded as controls. RNFL thickness was compared between two groups of cases and controls. In addition, the correlation between VEP P100 latency and RNFL thickness in four quadrants of superior, nasal, inferior and temporal fields was estimated by spearman correlation coefficient. RNFL thickness between the patients with history of clinically isolated syndrome (CIS) was also compared to other two subgroups of RRMS and SPMS. Results There was significant negative correlation between VEP P100 latency and RNFL. In all four quadrants, with increasing VEP latency, RNFL thickness decreased. Furthermore, there was significant correlation between P100 latencies and mean RNFL thickness [Pearson correlation coefficient = -0.527, P < 0.001; RNFL (mean) = (-0.44 ± 0.087) × P100 + (153.6 ± 10.94)]. Comparing RNFL thickness between three groups of CIS, RRMS, and SPSM, no significant difference was detected in RNFL thickness (P > 0.05). Power analysis demonstrated that RNFL average had the highest area under curve. Conclusion OCT does have good correlations with P100 latency, indicating retinal non-myelinated axonal involvement in early stages in addition to the myelinated axonal involvement. However, it cannot be used as the sole test in evaluating visual pathway in optic neuritis and complementary tests as VEPs are recommended. PMID:24250852

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

    PubMed Central

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

    2014-01-01

    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

  17. Somatosensory spatial attention modulates amplitudes, latencies, and latency jitter of laser-evoked brain potentials

    PubMed Central

    Franz, Marcel; Nickel, Moritz M.; Ritter, Alexander; Miltner, Wolfgang H. R.

    2015-01-01

    Several studies provided evidence that the amplitudes of laser-evoked potentials (LEPs) are modulated by attention. However, previous reports were based on across-trial averaging of LEP responses at the expense of losing information about intertrial variability related to attentional modulation. The aim of this study was to investigate the effects of somatosensory spatial attention on single-trial parameters (i.e., amplitudes, latencies, and latency jitter) of LEP components (N2 and P2). Twelve subjects participated in a sustained spatial attention paradigm while noxious laser stimuli (left hand) and noxious electrical stimuli (right hand) were sequentially delivered to the dorsum of the respective hand with nonnoxious air puffs randomly interspersed within the sequence of noxious stimuli. Participants were instructed to mentally count all stimuli (i.e., noxious and nonnoxious) applied to the attended location. Laser stimuli, presented to the attended hand (ALS), elicited larger single-trial amplitudes of the N2 component compared with unattended laser stimuli (ULS). In contrast, single-trial amplitudes of the P2 component were not significantly affected by spatial attention. Single-trial latencies of the N2 and P2 were significantly smaller for ALS vs. ULS. Additionally, the across-trial latency jitter of the N2 component was reduced for ALS. Conversely, the latency jitter of the P2 component was smaller for ULS compared with ALS. With the use of single-trial analysis, the study provided new insights into brain dynamics of LEPs related to spatial attention. Our results indicate that single-trial parameters of LEP components are differentially modulated by spatial attention. PMID:25673731

  18. Steady-state sweep visual evoked potential processing denoised by wavelet transform

    NASA Astrophysics Data System (ADS)

    Weiderpass, Heinar A.; Yamamoto, Jorge F.; Salomão, Solange R.; Berezovsky, Adriana; Pereira, Josenilson M.; Sacai, Paula Y.; de Oliveira, José P.; Costa, Marcio A.; Burattini, Marcelo N.

    2008-03-01

    Visually evoked potential (VEP) is a very small electrical signal originated in the visual cortex in response to periodic visual stimulation. Sweep-VEP is a modified VEP procedure used to measure grating visual acuity in non-verbal and preverbal patients. This biopotential is buried in a large amount of electroencephalographic (EEG) noise and movement related artifact. The signal-to-noise ratio (SNR) plays a dominant role in determining both systematic and statistic errors. The purpose of this study is to present a method based on wavelet transform technique for filtering and extracting steady-state sweep-VEP. Counter-phase sine-wave luminance gratings modulated at 6 Hz were used as stimuli to determine sweep-VEP grating acuity thresholds. The amplitude and phase of the second-harmonic (12 Hz) pattern reversal response were analyzed using the fast Fourier transform after the wavelet filtering. The wavelet transform method was used to decompose the VEP signal into wavelet coefficients by a discrete wavelet analysis to determine which coefficients yield significant activity at the corresponding frequency. In a subsequent step only significant coefficients were considered and the remaining was set to zero allowing a reconstruction of the VEP signal. This procedure resulted in filtering out other frequencies that were considered noise. Numerical simulations and analyses of human VEP data showed that this method has provided higher SNR when compared with the classical recursive least squares (RLS) method. An additional advantage was a more appropriate phase analysis showing more realistic second-harmonic amplitude value during phase brake.

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

    PubMed

    Quante, Markus; Lorenz, Jürgen; Hauck, Michael

    2010-02-01

    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

  20. Single-Trial Visual Evoked Potential Extraction Using Partial Least-Squares-Based Approach.

    PubMed

    Kristina Yanti, Duma; Zuki Yusoff, Mohd; Sagayan Asirvadam, Vijanth

    2016-01-01

    A single-trial extraction of a visual evoked potential (VEP) signal based on the partial least-squares (PLS) regression method has been proposed in this paper. This paper has focused on the extraction and estimation of the latencies of P100, P200, P300, N75, and N135 in the artificial electroencephalograph (EEG) signal. The real EEG signal obtained from the hospital was only concentrated on the P100. The performance of the PLS has been evaluated mainly on the basis of latency error rate of the peaks for the artificial EEG signal, and the mean peak detection and standard deviation for the real EEG signal. The simulation results show that the proposed PLS algorithm is capable of reconstructing the EEG signal into its desired shape of the ideal VEP. For P100, the proposed PLS algorithm is able to provide comparable results to the generalized eigenvalue decomposition (GEVD) algorithm, which alters (prewhitens) the EEG input signal using the prestimulation EEG signal. It has also shown better performance for later peaks (P200 and P300). The PLS outperformed not only in positive peaks but also in N75. In P100, the PLS was comparable with the GEVD although N135 was better estimated by GEVD. The proposed PLS algorithm is comparable to GEVD given that PLS does not alter the EEG input signal. The PLS algorithm gives the best estimate to multitrial ensemble averaging. This research offers benefits such as avoiding patient's fatigue during VEP test measurement in the hospital, in BCI applications and in EEG-fMRI integration. PMID:25376049

  1. Multifocal visual evoked potentials are influenced by variable contrast stimulation in MS

    PubMed Central

    Frohman, Audrey R.; Schnurman, Zane; Conger, Amy; Conger, Darrel; Beh, Shin; Greenberg, Benjamin; Sutter, Erich; Calabresi, Peter A.; Balcer, Laura J.; Frohman, Teresa C.

    2012-01-01

    Objective: To test the hypothesis that patients with multiple sclerosis (MS) with intereye asymmetry on low contrast letter acuity, and thickness of the retinal nerve fiber layer (RNFL), would exhibit corresponding changes in cortical timing and amplitude responses on pattern reversal multifocal visual evoked potentials (mfVEP), contingent upon variable stimulus contrast. Methods: In a cross-sectional study, we investigated a cohort of 11 normal subjects and 40 patients with MS, 21 of whom had a history of acute optic neuritis (MS-AON) with an intereye asymmetry with respect to RNFL thickness, and on low contrast letter acuity performance. Pattern reversal mfVEP was performed at high (100%), low (33.3%), and very low (14.2%) Michelson-contrast levels. Results: Compared to baseline measures at 100% contrast, the mean amplitude of the mfVEP was reduced in MS-AON eyes, upon pattern-reversal stimulation at the 2 lower contrast levels (p < 0.0001). With respect to changes in timing responses, the intereye asymmetry was increased in the MS-AON patients upon lower contrast pattern-reversal stimulation (p < 0.0001 for 33.3% compared to 100%, and p < 0.001 for 14.2% compared to 100%). The fellow eye in 12 (57%; p < 0.001) of the patients with an abnormal eye, and a history of AON, revealed abnormal amplitude and timing responses upon low contrast stimulation (signifying unmasking of occult damage). Conclusions: Our findings support the hypothesis that mfVEP metric abnormalities are contingent upon contrast magnitude during pattern reversal stimulation. Further, this paradigm was capable of unmasking occult abnormalities in a significant number of apparently unaffected eyes. PMID:22815550

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

    PubMed

    Vrca, A; Bozikov, V; Brzović, Z; Fuchs, R; Malinar, M

    1996-01-01

    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 192.7 days (SD +/- 77.6), mean loss of body mass during imprisonment 19.32% (SD +/- 9.54), and the average number of reported blows to the head and neck was 25.7 (SD +/- 20.3). VEPs were determined on average 290.5 days after the last craniocerebral trauma caused by blows to the head and neck (SD +/- 152.0) i.e., on average 218.5 days after release from the camp (SD +/- 164.3). Although all the 57 POWs reported being maltreated to a certain extent, 14 reported being subjected to particularly brutal forms of torture, 5 had been held in solitary confinement and 25 had lost consciousness at least once. Solitary confinement and loss of consciousness had the most significant effect on VEPs, and the altered VEP parameters correlated significantly with the craniocerebral trauma experienced, loss of body mass and the length of time since the last craniocerebral trauma until examination, and from release until examination. However, the length of imprisonment and treatment in the camps did not have a significant effect on VEP parameters. The study confirmed that under such conditions the age of the subject is a risk factor. The results of this study also confirmed that prisoners in one camp had been subjected to the worst maltreatment. PMID:8956983

  3. Nociceptive pathway function is normal in cervical dystonia: a study using laser-evoked potentials.

    PubMed

    Tinazzi, Michele; Valeriani, Massimiliano; Squintani, Giovanna; Corrà, Federica; Recchia, Serena; Defazio, Giovanni; Berardelli, Alfredo

    2012-10-01

    Cervical dystonia (CD) is often associated with pain in the neck muscles, though the mechanisms underlying pain in this condition are still largely unknown. The aim of this study was to assess laser pain rating and CO(2) laser-evoked potentials (LEPs) in CD patients with pain in the posterior neck region. We assessed the N2/P2 LEP complex and laser pain rating in a group of 20 CD patients and in 21 normal subjects. In 11 of the 20 CD patients (group I), the N2/P2 complex was recorded after stimulation of the skin overlying the right and left deltoid muscles (painless and non-dystonic). In the remaining nine CD patients (group II), the N2/P2 complex was recorded after stimulation of the skin over the splenius capitis muscle (painful and dystonic) and after stimulation of the skin overlying the contralateral splenius muscle (painless and non-dystonic). In group I patients, the N2/P2 LEP amplitude and laser pain rating after stimulation of both shoulders did not differ significantly from those obtained in normal subjects. Similarly, in group II patients, the N2/P2 LEP amplitude and laser pain rating after stimulation of the painful and dystonic splenius capitis muscle did not differ significantly from those obtained from either the contralateral painless, non-dystonic splenius capitis or normal subjects. The results of this study demonstrate that cutaneous nociceptive pathway function in CD patients is normal, thereby indicating that muscle pain in CD is not associated with any central sensitization of nociceptive inputs in either painful (dystonic) or non-painful (non-dystonic) body areas. PMID:22349875

  4. Effect of sevoflurane concentration on visual evoked potentials with pattern stimulation in dogs

    PubMed Central

    ITO, Yosuke; MAEHARA, Seiya; ITOH, Yoshiki; HAYASHI, Miri; KUBO, Akira; ITAMI, Takaharu; ISHIZUKA, Tomohito; TAMURA, Jun; YAMASHITA, Kazuto

    2014-01-01

    The purpose of this study was to investigate the effects of sevoflurane concentration on canine visual evoked potentials with pattern stimulation (P-VEPs). Six clinically normal laboratory-beagle dogs were used. The minimum alveolar concentration (MAC) of sevoflurane was detected from all subjects by tail clamp method. The refractive power of the right eyes of all subjects was corrected to −2 diopters after skiascopy. For P-VEP recording, the recording and reference electrode were positioned at inion and nasion, respectively, and the earth electrode was positioned on the inner surface. To grasp the state of CNS suppression objectively, the bispectral index (BIS) value was used. The stimulus pattern size and distance for VEP recording were constant, 50.3 arc-min and 50 cm, respectively. P-VEPs and BIS values were recorded under sevoflurane in oxygen inhalational anesthesia at 0.5, 1.0, 1.5, 2.0, 2.5 and 2.75 sevoflurane MAC. For analysis of P-VEP, the P100 implicit time and N75-P100 amplitude were estimated. P-VEPs were detected at 0.5 to 1.5 MAC in all dogs, and disappeared at 2.0 MAC in four dogs and at 2.5 and 2.75 MAC in one dog each. The BIS value decreased with increasing sevoflurane MAC, and burst suppression began to appear from 1.5 MAC. There was no significant change in P100 implicit time and N75-P100 amplitude with any concentration of sevoflurane. At concentrations around 1.5 MAC, which are used routinely to immobilize dogs, sevoflurane showed no effect on P-VEP. PMID:25373729

  5. [Correlated study of visual evoked potentials-polyneuropathy in diabetic patients without retinopathy].

    PubMed

    Aguggia, M; Baruchello, M; Dimanico, U; Filippi, P; Gilli, M; Riccio, A

    1993-05-01

    The functional study of visual pathways by means of pattern reversals VEPs (visual evoked potentials) was used as a noninvasive method in the study of diabetic patients, but the correlations between alterations in VEPs and the involvement of peripheral nervous system were not explored. Among 35 diabetic patients not suffering from retinopathy, we tested early deteriorations in visual pathways by means of pattern reversals VEPs and we considered similarities between these alterations, clinical metabolic parameters of the disease and clinical and paraclinical aspects of polyneuropathy (PNP). Four of these patients were insulin-dependent and 31 non-insulin-dependent, all with normal electroretinography and fluorangiography. Monitoring control of diabetes was performed by measuring hemoglobin HbA1. The control group was composed of 35 healthy subjects with normal neurologic and ophthalmologic examinations and normal visual acuity. In all subjects we tested four peripheral nerve conduction velocities (PNCV) (sensory and motor conduction of median nerve, motor conduction of peroneal nerve, anthidromic sensory conduction of sural nerve) diabetic patients were distributed in two groups according to the presence (group A, 15 patients) or absence (group B, 20 patients) of polyneuropathy. Pattern reversals PEVs were recorded after mono and binocular stimulation; screen was 25 x 18 cm with black and white check board pattern, check size 1.1 cm. Subject-to-stimulus distance was 1 m, corresponded to a visual angle of 38 degrees. Active electrode were located in Oz, O1 and O2, reference electrode in Fz.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8316340

  6. The role of nicotine on respiratory sensory gating measured by respiratory-related evoked potentials.

    PubMed

    Chan, Pei-Ying Sarah; Davenport, P W

    2010-03-01

    Respiratory perception can be altered by changes in emotional or psychological states. This may be due to affective (i.e., anxiety) modulation of respiratory sensory gating. Nicotine withdrawal induces elevated anxiety and decreased somatosensory gating. Respiratory sensory gating is evidenced by decreased amplitude of the respiratory-related evoked potentials (RREP) N(1) peak for the second occlusion (S2) when two 150-ms occlusions are presented with a 500-ms interval during an inspiration. The N(1) peak amplitude ratio of the S2 and first occlusion (S1) (S2/S1) is <0.5 and due to central neural sensory gating. We hypothesized that withdrawal from nicotine is anxiogenic and reduces respiratory gating in smokers. The RREP was recorded in smokers with 12-h withdrawal from nicotine and nonsmokers using a paired occlusion protocol. In smokers, the RREP was measured after nicotine withdrawal, then with either nicotine or placebo gum, followed by the second RREP trial. Nonsmokers received only placebo gum. After nicotine withdrawal, the smokers had a higher state anxiety compared with nonsmokers. There was a significant interaction between groups (nonsmokers vs. smokers with nicotine vs. smokers with placebo) and test (pre- vs. posttreatment) in RREP N(1) peak amplitude S2/S1. The S2/S1 in the smokers were larger than in nonsmokers before treatment. After gum treatment, the smoker-with-placebo group had a significantly larger S2/S1 than the other two groups. The S2/S1 was significantly decreased after the administration of nicotine gum in smokers due to significantly decreased S2 amplitudes. The RREP N(f) and P(1) peaks were unaffected. These results demonstrated that respiratory sensory gating was decreased in smokers after nicotine withdrawal. Nicotine increased respiratory sensory gating in smokers with a S2/S1 similar to that of the nonsmokers. Nicotine did not change respiratory sensory information arrival, but secondary information processing in respiratory sensation. PMID:20056851

  7. Compound gravity receptor polarization vectors evidenced by linear vestibular evoked potentials

    NASA Technical Reports Server (NTRS)

    Jones, S. M.; Jones, T. A.; Bell, P. L.; Taylor, M. J.

    2001-01-01

    The utricle and saccule are gravity receptor organs of the vestibular system. These receptors rely on a high-density otoconial membrane to detect linear acceleration and the position of the cranium relative to Earth's gravitational vector. The linear vestibular evoked potential (VsEP) has been shown to be an effective non-invasive functional test specifically for otoconial gravity receptors (Jones et al., 1999). Moreover, there is some evidence that the VsEP can be used to independently test utricular and saccular function (Taylor et al., 1997; Jones et al., 1998). Here we characterize compound macular polarization vectors for the utricle and saccule in hatchling chickens. Pulsed linear acceleration stimuli were presented in two axes, the dorsoventral (DV, +/- Z axis) to isolate the saccule, and the interaural (IA, +/- Y axis) to isolate the utricle. Traditional signal averaging was used to resolve responses recorded from the surface of the skull. Latency and amplitude of eighth nerve components of the linear VsEP were measured. Gravity receptor responses exhibited clear preferences for one stimulus direction in each axis. With respect to each utricular macula, lateral translation in the IA axis produced maximum ipsilateral response amplitudes with substantially greater amplitude intensity (AI) slopes than medially directed movement. Downward caudal motions in the DV axis produced substantially larger response amplitudes and AI slopes. The results show that the macula lagena does not contribute to the VsEP compound polarization vectors of the sacculus and utricle. The findings suggest further that preferred compound vectors for the utricle depend on the pars externa (i.e. lateral hair cell field) whereas for the saccule they depend on pars interna (i.e. superior hair cell fields). These data provide evidence that maculae saccule and utricle can be selectively evaluated using the linear VsEP.

  8. Change in auditory evoked potential index and bispectral index during induction of anesthesia with anesthetic drugs.

    PubMed

    Matsushita, Sachiko; Oda, Shinya; Otaki, Kei; Nakane, Masaki; Kawamae, Kaneyuki

    2015-10-01

    The aim of this study was to evaluate the efficacy of the auditory evoked potential (AEP) index (aepEX) as an assessment tool for hypnosis during induction of various anesthetic drugs, and to compare its performance to that of the bispectral index (BIS). A total of 45 cases were divided into three groups based on the drugs used for anesthesia. Before anesthetic induction, BIS and AEP monitors were initiated. Anesthesia was induced through intravenous injection (IV) as follows: MP (n = 15) group, midazolam (0.1 mg/kg IV); TP (n = 15) group, thiopental (4 mg/kg IV); and KP (n = 15) group, ketamine (2 mg/kg IV). After loss of response (LOR), an infusion of 3 μg/ml propofol via a target-controlled infusion was initiated in all groups. AepEX and BIS were measured in the waking state (baseline) and at LOR (1 min after LOR), pre-intubation (1 min after previous intubation) and post-intubation (1 min after tracheal intubation finished). The value of aepEX significantly decreased in all groups with LOR and that of BIS also decreased except of KP group. No significant difference were observed in BIS values between baseline and LOR in the KS group. The aepEX might be more useful than BIS for hypnosis monitoring during anesthetic induction, particularly when drugs such as ketamine are used. PMID:25427598

  9. Extracting Visual Evoked Potentials from EEG Data Recorded During fMRI-guided Transcranial Magnetic Stimulation

    PubMed Central

    Sadeh, Boaz; Yovel, Galit

    2014-01-01

    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

  10. Advancing the detection of steady-state visual evoked potentials in brain–computer interfaces

    NASA Astrophysics Data System (ADS)

    Abu-Alqumsan, Mohammad; Peer, Angelika

    2016-06-01

    Objective. Spatial filtering has proved to be a powerful pre-processing step in detection of steady-state visual evoked potentials and boosted typical detection rates both in offline analysis and online SSVEP-based brain–computer interface applications. State-of-the-art detection methods and the spatial filters used thereby share many common foundations as they all build upon the second order statistics of the acquired Electroencephalographic (EEG) data, that is, its spatial autocovariance and cross-covariance with what is assumed to be a pure SSVEP response. The present study aims at highlighting the similarities and differences between these methods. Approach. We consider the canonical correlation analysis (CCA) method as a basis for the theoretical and empirical (with real EEG data) analysis of the state-of-the-art detection methods and the spatial filters used thereby. We build upon the findings of this analysis and prior research and propose a new detection method (CVARS) that combines the power of the canonical variates and that of the autoregressive spectral analysis in estimating the signal and noise power levels. Main results. We found that the multivariate synchronization index method and the maximum contrast combination method are variations of the CCA method. All three methods were found to provide relatively unreliable detections in low signal-to-noise ratio (SNR) regimes. CVARS and the minimum energy combination methods were found to provide better estimates for different SNR levels. Significance. Our theoretical and empirical results demonstrate that the proposed CVARS method outperforms other state-of-the-art detection methods when used in an unsupervised fashion. Furthermore, when used in a supervised fashion, a linear classifier learned from a short training session is able to estimate the hidden user intention, including the idle state (when the user is not attending to any stimulus), rapidly, accurately and reliably.

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

    PubMed

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

    2012-03-01

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

  12. Emotional modulation of experimental pain: a source imaging study of laser evoked potentials

    PubMed Central

    Stancak, Andrej; Fallon, Nicholas

    2013-01-01

    Negative emotions have been shown to augment experimental pain. As induced emotions alter brain activity, it is not clear whether pain augmentation during noxious stimulation would be related to neural activation existing prior to onset of a noxious stimulus or alternatively, whether emotional stimuli would only alter neural activity during the period of nociceptive processing. We analyzed the spatio-temporal patterns of laser evoked potentials (LEPs) occurring prior to and during the period of cortical processing of noxious laser stimuli during passive viewing of negative, positive, or neutral emotional pictures. Independent component analysis (ICA) was applied to series of source activation volumes, reconstructed using local autoregressive average model (LAURA). Pain was the strongest when laser stimuli were associated with negative emotional pictures. Prior to laser stimulus and during the first 100 ms after onset of laser stimulus, activations were seen in the left and right medial temporal cortex, cerebellum, posterior cingulate, and rostral cingulate/prefrontal cortex. In all these regions, positive or neutral pictures showed stronger activations than negative pictures. During laser stimulation, activations in the right and left anterior insula, temporal cortex and right anterior and posterior parietal cortex were stronger during negative than neutral or positive emotional pictures. Results suggest that negative emotional stimuli increase activation in the left and right anterior insula and temporal cortex, and right posterior and anterior parietal cortex only during the period of nociceptive processing. The role of background brain activation in emotional modulation of pain appears to be only permissive, and consisting in attenuation of activation in structures maintaining the resting state of the brain. PMID:24062659

  13. The effect of developmental exposure to cadmium (Cd) on visual evoked potentials (VEPs) and lipid peroxidation.

    PubMed

    Yargiçoğlu, P; Ağar, A; Oğuz, Y; Izgüt-Uysal, V N; Sentürk, U K; Oner, G

    1997-01-01

    Pregnant Swiss albino rats were divided into three groups: control (C), gestational exposure of Cd (G-Cd), and gestational/postnatal exposure of Cd (GP-Cd) groups. Control animals received tap water, and the rats of GP-Cd group received Cd as CdC12 in their drinking water during the experimental period. The G-Cd group was given Cd during pregnancy, but given tap water after birth. Twenty-two days after birth, 15 rats (for each group) were taken from their mothers and continued to be treated with Cd (GP-Cd group) or tap water (C and G-Cd groups) for an additional 38 days. On postnatal day (PND) 60, flash visual evoked potentials (FVEPs) were recorded with disc electrodes attached with collodion 0.5 cm in front of and behind bregma. The mean latencies on N1, P2, and P3 were prolonged in the GP-Cd group compared with controls. The mean latency of P3 was also significantly different between G-Cd and GP-Cd groups. P1-N1 and N1-P2 amplitudes of VEPs were significantly decreased in the GP-Cd group compared with control group. N1-P2 amplitude of the G-Cd group was significantly lower than that of the control group. Thiobarbituric acid reactive substances (TBARS) were determined as an indicator of lipid peroxidation. Our data showed that pre- and postnatal Cd treatment caused a significant increase of lipid peroxidation in the brain. PMID:9200142

  14. Exercise improves visual deficits tested by visual evoked potentials in streptozotocin-induced diabetic rats.

    PubMed

    Ozkaya, Y Gül; Ağar, Aysel; Hacioğlu, Gülay; Yargiçoğlu, Piraye

    2007-12-01

    Visual evoked potentials (VEP) can be used as an objective non-invasive method to study the electrical activity of the visual system. Latency and amplitude measurements of VEP demonstrated that diabetes mellitus has been associated with increases in the latencies whereas the amplitude measurements revealed contradictory results. Although physical exercise has been reported to reduce the complications of diabetes mellitus, the effect of exercise on the visual system remains unknown. We investigated the effects of long-term moderate physical exercise on VEP in streptozotocin (STZ)-diabetic rats. We also measured brain thiobarbituric acid-reactive substances (TBARS) to explore the possible contribution of lipid peroxidation on the visual system. Animals were divided into four groups: control (C), control exercise (CE), diabetic (D) and diabetic exercise (DE) groups. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). Three days after the confirmation of diabetes, DE and CE groups were trained by running on a motor-driven treadmill with a progressive eight-week programme. The animals began running at 10 m/min, 0 degrees slope, 10 min/day and reached a level of 28 m/min, 6 degrees slope, 60 min/day by week 8. TBARS were elevated and VEP latencies were delayed in diabetic rats, indicating diabetes-induced defects in the optic pathway. These prolonged latencies were restored by exercise training. VEP amplitudes of the DE group were found unaltered with the exception of a decrement in P(2)N(2) which represents an early component of VEP, suggesting that exercise improves visual system defects in diabetic animals at different levels of the optic pathway. PMID:18075235

  15. Task-specific changes in motor evoked potentials of lower limb muscles after different training interventions.

    PubMed

    Beck, S; Taube, W; Gruber, M; Amtage, F; Gollhofer, A; Schubert, M

    2007-11-01

    This study aimed to identify sites and mechanisms of long-term plasticity following lower limb muscle training. Two groups performing either a postural stability maintenance training (SMT) or a ballistic ankle strength training (BST) were compared to a non-training group. The hypothesis was that practicing of a self-initiated voluntary movement would facilitate cortico-spinal projections, while practicing fast automatic adjustments during stabilization of stance would reduce excitatory influence from the primary motor cortex. Training effects were expected to be confined to the practiced task. To test for training specificity, motor evoked potentials (MEP) induced by transcranial magnetic stimulation (TMS) were recorded at rest and during motor tasks that were similar to each training. Intracortical, cortico-spinal, as well as spinal parameters were assessed at rest and during these tasks. The results show high task and training specificity. Training effects were only observable during performance of the trained task. While MEP size was decreased in the SMT group for the trained tasks, MEP recruitment was increased in the BST group in the trained task only. The control group did not show any changes. Background electromyogram levels, M. soleus H-reflex amplitudes and intracortical parameters were unaltered. In summary, it is suggested that the changes of MEP parameters in both training groups, but not in the control group, reflect cortical motor plasticity. While cortico-spinal activation was enhanced in the BST group, SMT may be associated with improved motor control through increased inhibitory trans-cortical effects. Since spinal excitability remained unaltered, changes most likely occur on the supraspinal level. PMID:17889840

  16. Short latency vestibular evoked potentials in the Japanese quail (Coturnix coturnix japonica)

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Short-latency vestibular-evoked potentials to pulsed linear acceleration were characterized in the quail. Responses occurred within 8 ms following the onset of stimuli and were composed of a series of positive and negative peaks. The latencies and amplitudes of the first four peaks were quantitatively characterized. Mean latencies at 1.0 g ms-1 ranged from 1265 +/- 208 microseconds (P1, N = 18) to 4802 +/- 441 microseconds (N4, N = 13). Amplitudes ranged from 3.72 +/- 1.51 microV (P1/N1, N = 18) to 1.49 +/- 0.77 microV (P3/N3, N = 16). Latency-intensity (LI) slopes ranged from -38.7 +/- 7.3 microseconds dB-1 (P1, N = 18) to -71.6 +/- 21.9 microseconds dB-1 (N3, N = 15) and amplitude-intensity (AI) slopes ranged from 0.20 +/- 0.08 microV dB-1 (P1/N1, N = 18) to 0.07 +/- 0.04 microV dB-1 (P3/N3, N = 11). The mean response threshold across all animals was -21.83 +/- 3.34 dB re: 1.0 g ms-1 (N = 18). Responses remained after cochlear extirpation showing that they could not depend critically on cochlear activity. Responses were eliminated by destruction of the vestibular end organs, thus showing that responses depended critically and specifically on the vestibular system. The results demonstrate that the responses are vestibular and the findings provide a scientific basis for using vestibular responses to evaluate vestibular function through ontogeny and senescence in the quail.

  17. The Effects of Alcohol on Visual Evoked Potential and Multifocal Electroretinography

    PubMed Central

    2016-01-01

    The aim of this study was to investigate the acute effects of ethanol administration on pattern-reversal visual evoked potential (VEP) and multifocal electroretinography (mfERG). Fifteen healthy subjects with no ocular or general disease were recruited. VEP (0.25° pattern sizes) and mfERG with 19 elements in two recording segments were performed before ethanol administration to obtain baseline for each participant. A few days later, the participants visited again for VEP and mfERG measurements after ethanol administration. Ethanol (0.75 g/kg) was administered orally over the course of 30 minutes. VEP and blood alcohol concentration were evaluated one hour after ethanol administration, and mfERG was conducted after pupil dilation. The Wilcoxon signed-rank test was used to compare parameter changes after randomized eye selection. The mean blood alcohol concentration was 0.034% ± 0.05% by volume. VEP revealed a P100 latency delay (109.4 ± 5.3; 113.1 ± 8.2; P = 0.008) after alcohol administration. The P1 implicit time of ring 1 on mfERG showed a trend of shortening after alcohol administration (37.9 ± 1.0; 37.2 ± 1.5; P = 0.048). However, the changes did not show statistical significance after Bonferroni correction. In conclusion, orally administrated ethanol (0.75 g/kg) appears to suppress the central nervous system, but it is not clear whether alcohol intake affects the retina. PMID:27134502

  18. Prognostic value of somatosensory-evoked potentials in neurology: A critical review in hypoxic encephalopathy.

    PubMed

    Song, Yanhai; Prakash, Ravi; Reddy, Jayashankar

    2016-01-01

    Prediction of prognosis in comatose patients surviving a cardiac arrest is still one of the intractable problems in critical care neurology because of lack of fool-proof ways to assess the outcome. Of all these measures, somatosensory-evoked potential (SSEP) has been perhaps the most evaluated and heavily relied-upon tool over the past several decades for assessing coma. Recent studies have given rise to concerns regarding the "absoluteness" of SSEP signals for the prognostic evaluation of coma. In this critical review, we searched the literature to focus on studies conducted so far on the prognostic evaluation of postanoxic coma using SSEPs. All those studies published on the use of SSEP as a prognostication tool in postanoxic coma were reviewed. A narrative review was created that included the strengths as well as limitations of the use of SSEP in postanoxic coma. The use of SSEP in coma has been universal for the purpose of prognostication. However, it has its own advantages as well as limitations. The limitations include challenges in performing and getting SSEP signals during coma as well as the challenges involved in reading and interpreting the signals. The recent usage of therapeutic hypothermia has become another factor that often interferes with the SSEP recording. Finally, based on these study results, some recommendations are generated for the effective use of SSEPs in comatose patients for further prognostication. We advocate that SSEP should be an integral component for the assessment of postanoxic comatose patients due to its several advantages over other assessment tools. However, SSEP recordings should follow certain standards. One should be aware that its interpretation may be biased by several factors. The bias created by the concept of "self-fulfilling hypothesis" should always be borne in mind before discontinuation of life support systems in terminal patients. PMID:27147145

  19. Early detection of hepatic encephalopathy by recording visual evoked potential (VEP).

    PubMed

    Zamir, Doron; Storch, Shimon; Kovach, Ivan; Storch, Rita; Zamir, Chen

    2002-01-01

    The visual evoked potential (VEP) record in response to a pattern stimulus is a non invasive and reliable method of detecting central and peripheral nerve system abnormalities. VEP recording have been used in animals with fulminant hepatic failure, and also in-patients with hepatic encephalopathy and acute severe hepatitis. Our aims were: a. to evaluate the potency of PVEP in assessing hepatic encephalopathy. b. to find the rate of pathologic PVEP in patients with advanced liver cirrhosis. VEP was recorded in 14 chronic liver cirrhotic patients (6 alcoholic, 6 HCV-related, 2 cryptogenic) and 14 controls. Patients with any neurologic abnormalities were excluded from the study. All patients were subjected to the Mental State Score (MSS) test, and venous blood ammonia was measured on the same day of VEP recording. In 10/14 (71%) patients some VEP recording abnormality was detected. In the cirrhotic patients, P100 latency was significantly longer (P < 0.05) than in controls. Low amplitude was observed in 8 patients compared to controls. Marked increase of N75 (3 patients) and marked increase of N145 (2 patients) were observed. Mean blood ammonia and MSS score were normal in all patients. No correlation was found between both MSS score and blood ammonia levels and the P100 delay. Five out of 10 patients with pathologic VEP developed hepatic encephalpathy during a follow-up of one year, compared to one out of 4 patients with no pathology on VEP recording. VEP recording may be a valuable tool in assessing patients with early hepatic encephalopathy and in predicting encephalopathy. PMID:12533959

  20. A Specific Component of the Evoked Potential Mirrors Phasic Dopamine Neuron Activity during Conditioning

    PubMed Central

    Pan, Wei-Xing

    2015-01-01

    Midbrain dopamine (DA) neurons are thought to be a critical node in the circuitry that mediates reward learning. DA neurons receive diverse inputs from regions distributed throughout the neuraxis from frontal neocortex to the mesencephalon. While a great deal is known about changes in the activity of individual DA neurons during learning, much less is known about the functional changes in the microcircuits in which DA neurons are embedded. Here we used local field potentials recorded from the midbrain of behaving mice to show that the midbrain evoked potential (mEP) faithfully reflects the temporal and spatial structure of the phasic response of midbrain neuron populations during conditioning. By comparing the mEP to simultaneously recorded single units, we identified specific components of the mEP that corresponded to phasic DA and non-DA responses to salient stimuli. The DA component of the mEP emerged with the acquisition of a conditioned stimulus, was extinguished following changes in reinforcement contingency, and could be inhibited by pharmacological manipulations that attenuate the phasic responses of DA neurons. In contrast to single-unit recordings, the mEP permitted relatively dense sampling of the midbrain circuit during conditioning and thus could be used to reveal the spatiotemporal structure of multiple intermingled midbrain circuits. Finally, the mEP response was stable for months and thus provides a new approach to study long-term changes in the organization of ventral midbrain microcircuits during learning. SIGNIFICANCE STATEMENT Neurons that synthesize and release the neurotransmitter dopamine play a critical role in voluntary reward-seeking behavior. Much of our insight into the function of dopamine neurons comes from recordings of individual cells in behaving animals; however, it is notoriously difficult to record from dopamine neurons due to their sparsity and depth, as well as the presence of intermingled non-dopaminergic neurons. Here we show that much of the information that can be learned from recordings of individual dopamine and non-dopamine neurons is also revealed by changes in specific components of the local field potential. This technique provides an accessible measurement that could prove critical to our burgeoning understanding of the molecular, functional, and anatomical diversity of neuron populations in the midbrain. PMID:26203140

  1. A Specific Component of the Evoked Potential Mirrors Phasic Dopamine Neuron Activity during Conditioning.

    PubMed

    Pan, Wei-Xing; Dudman, Joshua T

    2015-07-22

    Midbrain dopamine (DA) neurons are thought to be a critical node in the circuitry that mediates reward learning. DA neurons receive diverse inputs from regions distributed throughout the neuraxis from frontal neocortex to the mesencephalon. While a great deal is known about changes in the activity of individual DA neurons during learning, much less is known about the functional changes in the microcircuits in which DA neurons are embedded. Here we used local field potentials recorded from the midbrain of behaving mice to show that the midbrain evoked potential (mEP) faithfully reflects the temporal and spatial structure of the phasic response of midbrain neuron populations during conditioning. By comparing the mEP to simultaneously recorded single units, we identified specific components of the mEP that corresponded to phasic DA and non-DA responses to salient stimuli. The DA component of the mEP emerged with the acquisition of a conditioned stimulus, was extinguished following changes in reinforcement contingency, and could be inhibited by pharmacological manipulations that attenuate the phasic responses of DA neurons. In contrast to single-unit recordings, the mEP permitted relatively dense sampling of the midbrain circuit during conditioning and thus could be used to reveal the spatiotemporal structure of multiple intermingled midbrain circuits. Finally, the mEP response was stable for months and thus provides a new approach to study long-term changes in the organization of ventral midbrain microcircuits during learning. Significance statement: Neurons that synthesize and release the neurotransmitter dopamine play a critical role in voluntary reward-seeking behavior. Much of our insight into the function of dopamine neurons comes from recordings of individual cells in behaving animals; however, it is notoriously difficult to record from dopamine neurons due to their sparsity and depth, as well as the presence of intermingled non-dopaminergic neurons. Here we show that much of the information that can be learned from recordings of individual dopamine and non-dopamine neurons is also revealed by changes in specific components of the local field potential. This technique provides an accessible measurement that could prove critical to our burgeoning understanding of the molecular, functional, and anatomical diversity of neuron populations in the midbrain. PMID:26203140

  2. Cl- - and K+-dependent inhibitory postsynaptic potentials evoked by interneurones of the rat lateral geniculate nucleus.

    PubMed Central

    Crunelli, V; Haby, M; Jassik-Gerschenfeld, D; Leresche, N; Pirchio, M

    1988-01-01

    1. Hyperpolarizing potentials evoked by electrical stimulation of the optic tract were studied in projection cells of the rat dorsal lateral geniculate nucleus (LGN) in vitro. In the same cells the effects of gamma-amino butyric acid (GABA), baclofen and acetylcholine (ACh) were also investigated. 2. In the majority of cells a short- (SHP) (34 ms) and a long-lasting (LHP) (240 ms) hyperpolarizing potential could be recorded in the presence and in the absence of a preceding EPSP. They were blocked by tetrodotoxin (1 microM) and were more sensitive than the monosynaptic EPSP to a low-Ca2+-high-Mg2+ solution. 3. The SHP was associated with a marked decrease (75%) in input resistance, was blocked by bicuculline (1-100 microM) and its reversal potential (-67 mV) was dependent on the extracellular Cl- concentration. 4. The LHP was associated with a smaller decrease (45%) in input resistance and its reversal potential (-76 mV) was dependent on the extracellular K+ concentration. It was increased by bicuculline (100% at 50 microM) and nipecotic acid (30% at 10 microM), blocked by Ba2+ (1 mM), and unaffected by eserine (1-10 microM), neostigmine (1-10 microM) or by recording with EGTA-filled electrodes. In the presence of bicuculline, a single LHP was able to evoke, as a rebound response, a low-threshold Ca2+ spike that was, however, not followed by another LHP (or any other long-lasting hyperpolarization). 5. Ionophoretic applications of GABA evoked in the same cell a Cl- -dependent hyperpolarization (reversal potential: -65 mV) and/or depolarization, both of which were associated with a marked decrease (91%) in input resistance and abolished by bicuculline. GABA was also able to evoke a bicuculline-insensitive, K+-dependent hyperpolarization that had a reversal potential of -75 mV and was associated with a smaller decrease (43%) in input resistance. 6. Baclofen, applied by ionophoresis, pressure ejection or in the perfusion medium (1-100 microM), produced a hyperpolarization that had a reversal potential of -79 mV and was associated with a decrease (45%) in input resistance. 7. In the majority of cells (thirty-seven out of forty) ACh evoked a slow depolarization and only in three cells a hyperpolarization which had a reversal potential of -80 mV.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3404460

  3. Neurosurgical procedures, spinal nerve roots - one stage removal of thoracic dumb-bell tumor: role of spinal evoked potential.

    PubMed

    Srivastava, Dharmendra Kumar; Singh, Deepak; Tiwari, Bhuwan Chandra; Awasthi, Namarata; Hussain, Nuzhat

    2014-02-01

    We report a rare case of benign thoracic dumb-bell tumor in the upper posterior mediastinum, which was successfully removed by posterolateral thoracotomy and foraminotomy, using intraoperative monitoring of spinal motor-evoked potentials. This technique has many advantages including minimal morbidity and mortality, a single incision, one-step complete resection with adequate exposure, spinal stabilization, avoidance of laminectomy, nerve root identification, and good predicted postoperative function. PMID:24585801

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  5. Sensations and trigeminal somatosensory-evoked potentials elicited by electrical stimulation of endosseous oral implants in humans.

    PubMed

    Van Loven, K; Jacobs, R; Swinnen, A; Van Huffel, S; Van Hees, J; van Steenberghe, D

    2000-12-01

    The perception of bipolar electrical stimuli through implants was studied. The stimuli were delivered to permucosal oral endosseous implants in 15 individuals, who then reported tapping to beating sensations. In 10 out of the 15, these stimuli evoked clearly distinguishable potentials in the averaged electroencephalograms. The most prominent scalp potential was a positive wave with a latency between 18 and 25 ms, often preceded by a negative wave with a latency around 12-17 ms. In contrast, when a motor response was elicited by stimulation of the lip, a shorter latency wave around 8-11 ms was found additionally, indicating that the former-mentioned waves represent a true sensory response and not an artefact of myogenous origin. Furthermore, topical anaesthesia of the gingiva surrounding the implants in six individuals had little effect on the sensory responses. This evidence excluded peri-implant mucosal innervation as the origin of the perception and of the somatosensory-evoked waves elicited by the electrical stimulation of the oral implants. To the best of our knowledge, for the first time a sensation (osseoperception) has been elicited by electrical stimulation of endosseous oral implants and correlated with simultaneously recorded trigeminal somatosensory-evoked potentials (TSEPs). PMID:11084148

  6. Listening to the brainstem: musicianship enhances intelligibility of subcortical representations for speech.

    PubMed

    Weiss, Michael W; Bidelman, Gavin M

    2015-01-28

    Auditory experiences including musicianship and bilingualism have been shown to enhance subcortical speech encoding operating below conscious awareness. Yet, the behavioral consequence of such enhanced subcortical auditory processing remains undetermined. Exploiting their remarkable fidelity, we examined the intelligibility of auditory playbacks (i.e., "sonifications") of brainstem potentials recorded in human listeners. We found naive listeners' behavioral classification of sonifications was faster and more categorical when evaluating brain responses recorded in individuals with extensive musical training versus those recorded in nonmusicians. These results reveal stronger behaviorally relevant speech cues in musicians' neural representations and demonstrate causal evidence that superior subcortical processing creates a more comprehensible speech signal (i.e., to naive listeners). We infer that neural sonifications of speech-evoked brainstem responses could be used in the early detection of speech-language impairments due to neurodegenerative disorders, or in objectively measuring individual differences in speech reception solely by listening to individuals' brain activity. PMID:25632143

  7. The maturation of human evoked brain potentials to sounds presented at different stimulus rates

    PubMed Central

    Sussman, E.; Steinschneider, M.; Gumenyuk, V.; Grushko, J.; Lawson, K.

    2008-01-01

    The current study assessed the normal development of cortical auditory evoked potentials (CAEPs) in humans presented with pure tone stimuli at relatively fast stimulus rates. Traditionally, maturation of sound processing indexed by CAEPs has been studied in paradigms using inter-stimulus intervals (ISIs) generally slower than 1 Hz. While long ISIs may enhance the amplitude of CAEP components, speech information generally occurs at more rapid rates. These slower rates of sound presentation may not accurately assess auditory cortical functions in more realistic sound environments. We examined the effect of temporal rate on the elicitation of the P1—N1—P2—N2 components to unattended sounds at four levels of stimulus onset asynchrony (SOA, onset to onset, 200, 400, 600, and 800 ms) in children grouped separately by year (ages 8, 9, 10, 11 years), in adolescents (age 16 years) and in one group of young adults (ages 22–40 years). We found that both age and stimulus rate produced profound changes in CAEP morphology. Between the ages of 8–11 years, the P1 and N2 components dominated the ERP waveform at all stimulus rates. N1, the dominant CAEP component in adults, appeared as a bifurcation in a broad positive peak at earlier ages, and did not emerge as a separate component until adolescence. While the P1—N1—P2 components are more “adult-like” than “child-like” in the adolescent subjects, the N2 component, a hallmark of the child obligatory response, was still present. Faster rates resulted in the suppression of discrete components such that by 200 ms, only P1 in the adults and adolescents, and both P1 and N2 in the youngest children were discernable. We conclude that both age and ISI are important variables in the assessment of auditory cortex function and maturation. The presence of N2 in adolescents indicates that auditory cortical maturation persists into teen years. PMID:18207681

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  9. Wavelet analysis can sensitively describe dynamics of ethanol evoked local field potentials of the slug (Limax marginatus) brain.

    PubMed

    Schütt, Atsuko; Ito, Iori; Rosso, Osvaldo A; Figliola, Alejandra

    2003-10-30

    Odorants evoke characteristic, but complex, local field potentials (LFPs) in the molluscan brain. Wavelet tools in combination with Fourier analysis can detect and characterize hitherto unknown discrete, slow potentials underlying the conspicuous oscillations. Ethanol was one of the odorants that we have extensively studied (J. Neurosci. Methods, 119 (2002) 89). To detect new features and to elucidate their functions, we tested the wavelet tools on the ethanol-evoked LFP responses of the slug (Limax) procerebrum. Recordings were made in vitro from the neuropile and the cell layer. The present study led to the following findings: (i) Mutual exclusion. Energy concentrated mainly in two ranges, (a) 0.1-0.4 Hz and (b) 1.56-12.5 Hz, and the sum of energy remained constant throughout experiments regardless of the condition. A redistribution of relative energy within this sum seemed to occur in the course of main, possible interactions between the two components excluding each other ('mutual exclusion'). (ii) Transient signal ordering and disordering. Ethanol stimulation alternatingly evoked periods of strongly time evolving oscillation dominated by the energy of 1.56-12.5 Hz (increase of entropy=disordered or complexly ordered state) and those of near-silence were predominated by the energy of 0.1-0.4 Hz (decrease of entropy=ordered state). (iii) About 0.1 Hz slow wave oscillation. It was robust. The dominant energy oscillation and the resulting large entropy fluctuation were negatively correlated to each other, and revealed strong frequency-tuning or synchronization at this frequency. Our findings suggest that discrete slow waves play functionally important roles in the invertebrate brain, as widely known in vertebrate EEG. Wavelet tools allow an easy interpretation of several minutes of frequency variations in a single display and give precise information on stimulus-evoked complex change of the neural system describing the new state 'more ordered' or 'non-ordered or more complexly ordered'. PMID:14511817

  10. Can Motor Evoked Potentials Be an Objective Parameter to Assess Extremity Function at the Acute or Subacute Stroke Stage?

    PubMed Central

    Kim, Gi-Wook; Won, Yu Hui; Park, Sung-Hee; Seo, Jeong-Hwan

    2015-01-01

    Objective To investigate whether motor evoked potential (MEP) amplitude ratio measurements are sufficiently objective to assess functional activities of the extremities. We also delineated the distribution between the presence or absence of MEPs and the Medical Research Council (MRC) scale for muscle strength of the extremities. Methods We enrolled 183 patients with first-ever unilateral hemiplegia after stroke. The MEP parameters were amplitude ratio (amplitude of affected side/amplitude of unaffected side) recorded at the first dorsal interosseous (FDI) and tibialis anterior (TA) muscles. We performed frequency analyses using the MRC scale for muscle strength and the presence or absence of evoked MEPs. Change on the MRC scale, hand function tests (HFTs), and the Modified Barthel Index (MBI) subscore were compared between the evoked MEP and absent MEP groups using the independent t-test. Receiver operating characteristic curves were used to determine the optimal cutoff scores for the MEP amplitude ratio using the HFT results and MBI subscores. Correlations between the MEP amplitude ratio and the MRC scale, HFTs, and MBI subscore were analyzed. Results About 10% of patients with MRC scale grades 0-2 showed evoked MEPs at the FDI muscle, and 4% of patients with MRC scale grades 3-5 did not show MEPs. About 18% of patients with MRC scale grades 0-2 showed evoked MEPs at the TA muscle, and 4% of patients with MRC scale grades 3-5 did not show MEPs. MEP amplitude increased with increasing MRC scale grade. The evoked MEP group had more significant changes on the MRC scale, HFT, and the climbing stair score on the MBI than those in the group without MEPs. Larger MEP amplitude ratios were observed in patients who had more difficulty with the HFTs and ambulation. The MEP amplitude ratio was significantly correlated with the MRC scale, HFT, and MBI subscore. Conclusion We conclude that the MEP amplitude ratio may be useful to predict functional status of the extremities in patients who suffered stroke. PMID:25932422

  11. What is the validity of an "abnormal" evoked or event-related potential in MS? Auditory and visual evoked and event-related potentials in multiple sclerosis patients and normal subjects.

    PubMed

    van Dijk, J G; Jennekens-Schinkel, A; Caekebeke, J F; Singh, A; Zwinderman, A H

    1992-05-01

    The predictive validity of evoked potentials (EPs) and event-related potentials (ERPs) in multiple sclerosis (MS) has not yet been fully investigated, as only the sensitivity of these tests has sofar been reported. EPs (short, middle and long latency auditory evoked potentials and visual evoked potentials) and ERPs (visual and auditory) were studied in 19 controls and 30 multiple sclerosis (MS) patients. Abnormality thresholds of peak latencies were defined on the basis of the mean plus 2 or 3 standard deviations, based on data from the control group. The effects of changing the latency thresholds and including the absence of peaks in the abnormality definition were assessed. In accordance with earlier reports we found a high sensitivity (up to 93% for bimodal combined EPs and 47% for combined ERPs). False positive rates of separate peaks were low and conformed to expectation. However, combining separate peak measurements increased false positive rates of EPs and ERPs to unacceptably high levels (up to 58% for combined EPs and 32% for combined ERPs). Positive likelihood ratios for bimodal EPs were low (between 1.6 and 4.0, depending on the abnormality definition). They ranged from 1.4 to 2.2 for bimodal ERPs. Abnormal combined EPs or ERPs were therefore not the reliable indicators of functional damage that they are supposed to be. Separate EPs were much more reliable in this respect. ERPs failed to distinguish between the groups, either separately or in combination. Changing the latency threshold and including absent peaks in the abnormality definition influenced the abnormality rates in both groups.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1517760

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

    PubMed Central

    Radzikowska, Zofia; Milanowski, Piotr; Kuś, Rafał; Suffczyński, Piotr; Michalska, Magdalena; Łabęcki, Maciej; Zwoliński, Piotr; Durka, Piotr

    2014-01-01

    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

  13. Two-channel recording of auditory-evoked potentials to detect age-related deficits in temporal processing.

    PubMed

    Parthasarathy, Aravindakshan; Bartlett, Edward

    2012-07-01

    Auditory brainstem responses (ABRs), and envelope and frequency following responses (EFRs and FFRs) are widely used to study aberrant auditory processing in conditions such as aging. We have previously reported age-related deficits in auditory processing for rapid amplitude modulation (AM) frequencies using EFRs recorded from a single channel. However, sensitive testing of EFRs along a wide range of modulation frequencies is required to gain a more complete understanding of the auditory processing deficits. In this study, ABRs and EFRs were recorded simultaneously from two electrode configurations in young and old Fischer-344 rats, a common auditory aging model. Analysis shows that the two channels respond most sensitively to complementary AM frequencies. Channel 1, recorded from Fz to mastoid, responds better to faster AM frequencies in the 100-700 Hz range of frequencies, while Channel 2, recorded from the inter-aural line to the mastoid, responds better to slower AM frequencies in the 16-100 Hz range. Simultaneous recording of Channels 1 and 2 using AM stimuli with varying sound levels and modulation depths show that age-related deficits in temporal processing are not present at slower AM frequencies but only at more rapid ones, which would not have been apparent recording from either channel alone. Comparison of EFRs between un-anesthetized and isoflurane-anesthetized recordings in young animals, as well as comparison with previously published ABR waveforms, suggests that the generators of Channel 1 may emphasize more caudal brainstem structures while those of Channel 2 may emphasize more rostral auditory nuclei including the inferior colliculus and the forebrain, with the boundary of separation potentially along the cochlear nucleus/superior olivary complex. Simultaneous two-channel recording of EFRs help to give a more complete understanding of the properties of auditory temporal processing over a wide range of modulation frequencies which is useful in understanding neural representations of sound stimuli in normal, developmental or pathological conditions. PMID:22560961

  14. The developmental effects of extremely low frequency electric fields on visual and somatosensory evoked potentials in adult rats.

    PubMed

    Gok, Deniz Kantar; Akpinar, Deniz; Hidisoglu, Enis; Ozen, Sukru; Agar, Aysel; Yargicoglu, Piraye

    2016-01-01

    The purpose of our study was to investigate the developmental effects of extremely low frequency electric fields (ELF-EFs) on visual evoked potentials (VEPs) and somatosensory-evoked potentials (SEPs) and to examine the relationship between lipid peroxidation and changes of these potentials. In this context, thiobarbituric acid reactive substances (TBARS) levels were determined as an indicator of lipid peroxidation. Wistar albino female rats were divided into four groups; Control (C), gestational (prenatal) exposure (Pr), gestational+ postnatal exposure (PP) and postnatal exposure (Po) groups. Pregnant rats of Pr and PP groups were exposed to 50 Hz electric field (EF) (12 kV/m; 1 h/day), while those of C and Po groups were placed in an inactive system during pregnancy. Following parturition, rats of PP and Po groups were exposed to ELF-EFs whereas rats of C and Pr groups were kept under the same experimental conditions without being exposed to any EF during 68 days. On postnatal day 90, rats were prepared for VEP and SEP recordings. The latencies of VEP components in all experimental groups were significantly prolonged versus C group. For SEPs, all components of PP group, P2, N2 components of Pr group and P1, P2, N2 components of Po group were delayed versus C group. As brain TBARS levels were significantly increased in Pr and Po groups, retina TBARS levels were significantly elevated in all experimental groups versus C group. In conclusion, alterations seen in evoked potentials, at least partly, could be explained by lipid peroxidation in the retina and brain. PMID:25496054

  15. Effects of Motion Sickness Severity on the Vestibular-Evoked Myogenic Potentials

    PubMed Central

    Fowler, Cynthia G.; Sweet, Amanda; Steffel, Emily

    2015-01-01

    Background Motion sickness is a common debilitating condition associated with both actual and perceived motion. Despite the commonality, little is known about the underlying physiological mechanisms. One theory proposes that motion sickness arises from a mismatch between reality and past experience in vertical motions. Physiological tests of the vestibular system, however, have been inconclusive regarding the underlying pathogenesis. Cervical vestibular-evoked myogenic potentials (cVEMPs) arise from the saccule, which responds to vertical motion. If vertical motion elicits motion sickness, the cVEMP should be affected. Purpose The purpose of this investigation was to determine if cVEMP characteristics differ among individuals with a range of motion sickness susceptibility from negligible to severe. The hypothesis was that individuals with high susceptibility would have larger cVEMP amplitudes and shorter cVEMP latencies relative to those who are resistant to motion sickness. Research Design The study had two parts. The first was quasi-experimental in which participants comprised three groups based on susceptibility to motion sickness (low, mild-moderate, high) as identified on the short version of the Motion Sickness Susceptibility Questionnaire (MSSQ-S). The second part of the study was correlational and evaluated the specific relationships between the degree of motion sickness susceptibility and characteristics of the VEMPs. Study Sample A total of 24 healthy young adults (ages 20–24 yr) were recruited from the university and the community without regard to motion sickness severity. Data Collection and Analysis Participants took the MSSQ-S, which quantifies susceptibility to motion sickness. The participants had a range of motion sickness susceptibility with MSSQ raw scores from 0.0–36.6, which correspond to percent susceptibility from 0.0–99.3%. VEMPs were elicited by 500 Hz tone-bursts monaurally in both ears at 120 dB pSPL. MSSQ-S percent scores were used to divide the participants into low, mild-moderate, and high susceptibility groups. A fixed general linear model with repeated-measures analysis of variance tested cVEMP characteristics for the susceptibility groups (between participants) and ears (within participants). A univariate analysis of variance tested the cVEMP interaural amplitudes across groups. The second analysis was a regression of the severity of motion sickness in percent on cVEMP characteristics. Significance was defined as p < 0.05. Results Participants in the high susceptibility group had significantly higher cVEMP amplitudes than those in the low susceptibility group. cVEMP amplitudes did not differ between ears, and latencies did not differ between the two groups or between ears. Regression analysis on MSSQ-S percent susceptibility by VEMP amplitudes revealed a best-fit cubic function in both ears, with r2 values of more than 42%. The interaural asymmetry ratio was negatively associated with motion sickness susceptibility (r2 = 0.389). Conclusions The current study is the first to report that greater susceptibility to motion sickness is associated with larger cVEMP amplitudes and lower interaural cVEMP asymmetries. Larger interaural asymmetries in cVEMPs did not promote motion sickness susceptibility. The cVEMP findings implicate the saccule and its neural pathways in the production of motion sickness and are consistent with the theory that vertical motions elicit motion sickness. Motion sickness susceptibility may contribute to the variability in normative cVEMP amplitudes. PMID:25405837

  16. [Phenomenological model of changes in evoked potentials of the sensomotor area of the large cerebral hemispheres during processing of conditioned reflexes].

    PubMed

    Chuprun, B E; Serdiuchenko, V M

    1999-01-01

    A phemenological model of variations in evoked potentials during conditioning is proposed. The model consists of four linear differentional equations. Variations in a wide range of only one parameter of the system of differential equations correspond to all variations in evoked potentials. A variation of this parameter in the presence of constant disturbances at the system input gives rise to the appearance of a constant or increasing signal at the output of the system, which is characteristic for the expectancy wave. PMID:10544829

  17. Antioxidant Treatments Recover the Alteration of Auditory-Evoked Potentials and Reduce Morphological Damage in the Inferior Colliculus after Perinatal Asphyxia in Rat.

    PubMed

    Revuelta, Miren; Arteaga, Olatz; Montalvo, Haizea; Alvarez, Antonia; Hilario, Enrique; Martinez-Ibargüen, Agustin

    2016-03-01

    Maturation of the auditory pathway is dependent on the central nervous system myelination and it can be affected by pathologies such as neonatal hypoxic ischemic (HI) encephalopathy. Our aim was to evaluate the functional integrity of the auditory pathway and to visualize, by histological and cellular methods, the damage to the brainstem using a neonatal rat model of HI brain injury. To carry out this morphofunctional evaluation, we studied the effects of the administration of the antioxidants nicotine, melatonin, resveratrol and docosahexaenoic acid after hypoxia-ischemia on the inferior colliculus and the auditory pathway. We found that the integrity of the auditory pathway in the brainstem was altered as a consequence of the HI insult. Thus, the auditory brainstem response (ABR) showed increased I-V and III-V wave latencies. At a histological level, HI altered the morphology of the inferior colliculus neurons, astrocytes and oligodendricytes, and at a molecular level, the mitochondria membrane potential and integrity was altered during the first hours after the HI and reactive oxygen species (ROS) activity is increased 12 h after the injury in the brainstem. Following antioxidant treatment, ABR interpeak latency intervals were restored and the body and brain weight was recovered as well as the morphology of the inferior colliculus that was similar to the control group. Our results support the hypothesis that antioxidant treatments have a protective effect on the functional changes of the auditory pathway and on the morphological damage which occurs after HI insult. PMID:25990815

  18. Audiogram of a stranded Blainville's beaked whale (Mesoplodon densirostris) measured using auditory evoked potentials.

    PubMed

    Pacini, Aude F; Nachtigall, Paul E; Quintos, Christopher T; Schofield, T David; Look, Dera A; Levine, Gregg A; Turner, Jason P

    2011-07-15

    Quantifying and understanding the impact of anthropogenic sound on marine mammals has been the focus of many researchers both in laboratory settings as well as in the field. This study presents the audiogram of a sub-adult Blainville's beaked whale that stranded in Hawaii. The hearing measurements were conducted using the non-invasive auditory brainstem response technique. A total of 11 sinusoidally amplitude modulated tones were tested ranging from 5.6 to 160 kHz. The audiogram data indicated that the region of best hearing was found between 40 and 50 kHz with thresholds below 50 dB. This frequency range partially overlaps with the frequency modulated upsweep that Blainville's beaked whales have been reported to use during echolocation. These results match the frequency range obtained from the hearing measurements of a Gervais' beaked whale previously tested using contact acoustic stimulation and emphasize the importance of obtaining rapid hearing measurements on live stranded animals to improve the understanding of poorly known species. PMID:21697433

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

    PubMed Central

    2015-01-01

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

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

    PubMed

    Zalar, Bojan; Martin, Tim; Kavcic, Voyko

    2015-06-01

    The slowing of information processing, a hallmark of cognitive aging, has several origins. Previously we reported that in a motion direction discrimination task, older as compared to younger participants showed prolonged non-decision time, an index of an early perceptual stage, while in motion onset visual evoked potentials (MO-VEPs) the P1 component was enhanced and N2 was diminished. We did not find any significant correlations between behavioral and MO-VEP measures. Here, we investigated the role of age in encoding and perceptual processing of stimulus onset visually evoked potentials (SO-VEPs). Twelve healthy adults (age<55years) and 19 elderly (age>55years) performed a motion direction discrimination task during EEG recording. Prior to motion, the stimulus consisted of a static cloud of white dots on a black background. As expected, SO-VEPs evoked well defined P1, N1, and P2 components. Elderly participants as compared to young participants showed increased P1 amplitude while their P2 amplitude was reduced. In addition elderly participants showed increased latencies for P1 and N1 components. Contrary to the findings with MO-VEPs, SO-VEP parameters were significant predictors of average response times and diffusion model parameters. Our electrophysiological results support the notion that slowing of information processing in older adults starts at the very beginning of encoding in visual cortical processing, most likely in striate and extrastriate visual cortices. More importantly, the earliest SO-VEP components, possibly reflecting configuration of visual cortices and encoding processes, predict subsequent prolonging and tardiness of perceptual and higher-level cognitive processes. PMID:25889693

  1. Requirements for synaptically evoked plateau potentials in relay cells of the dorsal lateral geniculate nucleus of the mouse

    PubMed Central

    Dilger, Emily K; Shin, Hee-Sup; Guido, William

    2011-01-01

    In developing cells of the mouse dorsal lateral geniculate nucleus (dLGN), synaptic responses evoked by optic tract (OT) stimulation give rise to long-lasting, high-amplitude depolarizations known as plateau potentials. These events are mediated by L-type Ca2+ channels and occur during early postnatal life, a time when retinogeniculate connections are remodelling. To better understand the relationship between L-type activity and dLGN development we used an in vitro thalamic slice preparation which preserves the retinal connections and intrinsic circuitry in dLGN and examined how synaptic responses evoked by OT stimulation lead to the activation of plateau potentials. By varying the strength and temporal frequency of OT stimulation we identified at least three factors that contribute to the developmental regulation of plateau activity: the degree of retinal convergence, the temporal pattern of retinal stimulation and the emergence of feed-forward inhibition. Before natural eye opening (postnatal day 14), the excitatory synaptic responses of relay cells receiving multiple retinal inputs summated in both the spatial and temporal domains to produce depolarizations sufficient to activate L-type activity. After eye opening, when inhibitory responses are fully developed, plateau activity was rarely evoked even with high temporal rates of OT stimulation. When the bulk of this inhibition was blocked by bath application of bicuculline, the incidence of plateau activity increased significantly. We also made use of a transgenic mouse that lacks the β3 subunit of the L-type Ca2+ channel. These mutants have far fewer membrane-bound Ca2+ channels and attenuated L-type activity. In β3 nulls, L-type plateau activity was rarely observed even at young ages when plateau activity prevails. Thus, in addition to the changing patterns of synaptic connectivity and retinal activity, the expression of L-type Ca2+ channels is a requisite component in the manifestation of plateau activity. PMID:21173075

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

    SciTech Connect

    Zhang, Feng; Zhang, Xin; Xie, Jun; Li, Yeping; Han, Chengcheng; Lili, Li; Wang, Jing; Xu, Guang-Hua

    2015-03-10

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

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

    PubMed

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

    2000-05-01

    In order to assess higher auditory processing capabilities, long-latency auditory evoked potentials (AEPs) were recorded to synthesized musical instrument tones in 22 post-comatose patients with severe brain injury causing variably attenuated behavioural responsiveness. On the basis of normative studies, three different types of spectro-temporal modulation were employed. When a continuous 'clarinet' tone changes pitch once every few seconds, N1/P2 potentials are evoked at latencies of approximately 90 and 180 ms, respectively. Their distribution in the fronto-central region is consistent with generators in the supratemporal cortex of both hemispheres. When the pitch is modulated at a much faster rate ( approximately 16 changes/s), responses to each change are virtually abolished but potentials with similar distribution are still elicited by changing the timbre (e.g. 'clarinet' to 'oboe') every few seconds. These responses appear to represent the cortical processes concerned with spectral pattern analysis and the grouping of frequency components to form sound 'objects'. Following a period of 16/s oscillation between two pitches, a more anteriorly distributed negativity is evoked on resumption of a steady pitch. Various lines of evidence suggest that this is probably equivalent to the 'mismatch negativity' (MMN), reflecting a pre-perceptual, memory-based process for detection of change in spectro-temporal sound patterns. This method requires no off-line subtraction of AEPs evoked by the onset of a tone, and the MMN is produced rapidly and robustly with considerably larger amplitude (usually >5 microV) than that to discontinuous pure tones. In the brain-injured patients, the presence of AEPs to two or more complex tone stimuli (in the combined assessment of two authors who were 'blind' to the clinical and behavioural data) was significantly associated with the demonstrable possession of discriminative hearing (the ability to respond differentially to verbal commands, in the assessment of a further author who was blind to the AEP findings). Behavioural and electrophysiological findings were in accordance in 18/22 patients, but no AEPs could be recorded in two patients who had clear behavioural evidence of discriminative hearing. The absence of long-latency AEPs should not, therefore, be considered indicative of complete functional deafness. Conversely, AEPs were substantially preserved in two patients without behavioural evidence of discriminative hearing. Although not necessarily indicative of conscious 'awareness', such AEP preservation might help to identify sentient patients who are prevented by severe motor disability from communicating their perception. PMID:10775545

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

    PubMed

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

    2015-11-01

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

  5. Simultaneous Detection of P300 and Steady-State Visually Evoked Potentials for Hybrid Brain-Computer Interface

    PubMed Central

    Combaz, Adrien; Van Hulle, Marc M.

    2015-01-01

    Objective We study the feasibility of a hybrid Brain-Computer Interface (BCI) combining simultaneous visual oddball and Steady-State Visually Evoked Potential (SSVEP) paradigms, where both types of stimuli are superimposed on a computer screen. Potentially, such a combination could result in a system being able to operate faster than a purely P300-based BCI and encode more targets than a purely SSVEP-based BCI. Approach We analyse the interactions between the brain responses of the two paradigms, and assess the possibility to detect simultaneously the brain activity evoked by both paradigms, in a series of 3 experiments where EEG data are analysed offline. Main Results Despite differences in the shape of the P300 response between pure oddball and hybrid condition, we observe that the classification accuracy of this P300 response is not affected by the SSVEP stimulation. We do not observe either any effect of the oddball stimulation on the power of the SSVEP response in the frequency of stimulation. Finally results from the last experiment show the possibility of detecting both types of brain responses simultaneously and suggest not only the feasibility of such hybrid BCI but also a gain over pure oddball- and pure SSVEP-based BCIs in terms of communication rate. PMID:25815815

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

    PubMed Central

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

    2015-01-01

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

  7. Clinical Use of Skull Tap Vestibular Evoked Myogenic Potentials for the Diagnoses of the Cerebellopontine Angle Tumor Patients

    PubMed Central

    Yavuz, Erdem; Lachowska, Magdalena; Piercha?a, Katarzyna; Morawski, Krzysztof; Niemczyk, Kazimierz; Delgado, Rafael E.

    2014-01-01

    Objective. To document our experiences using a new skull tapping induced Vestibular Evoked Myogenic Potentials (tap VEMPs) technique combined with standard Auditory Vestibular Evoked Myogenic Potentials (AC VEMPs) for advanced clinical assessment of cerebellopontine angle tumor (CPAT) patients. Design and Study Sample. Three patients were selected in order to highlight observations shown in a larger patient population and to show the variability of the findings. Both tap VEMPs and AC VEMPs were acquired from the sternocleidomastoid muscle (SCM) with EMG-based biofeedback and monitoring. Results. The usefulness of VEMPs was demonstrated, indicating the presence of a tumor and contributing additional information as to the involved nerve bundles in two out of the three cases. Conclusion. Due to the sensory organ dependency and related innervations differences, acquiring both AC VEMPs and tap VEMPs is likely to increase the probability of diagnosing CPATs and provide more information on the involved vestibular nerve bundles. This study demonstrates the feasibility of the possible expansion and combination of tap VEMPs and AC VEMPs techniques into a clinical diagnostic battery for advanced assessment of CPAT patients and its contribution as a guideline for the use of tap VEMPs in general. PMID:24804198

  8. 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...

  9. 12 WEEK EXPOSURE TO CARBONYL SULFIDE PRODUCES BRAIN LESIONS AND CHANGES IN BRAINSTEM AUDITORY (BAER) AND SOMATOSENAORY (SEP) EVOKED POTENTIALS IN FISCHER 344N RATS

    EPA Science Inventory

    Carbonyl sulfide (COS) is a chemical intermediate in the production of pesticides and herbicides, is a metabolite of carbon disulfide, is produced by the combustion of organic material, and is found occurring in nature. COS was included in a Toxic Substances Control Act request f...

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

    PubMed Central

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

    2016-01-01

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

  11. Specific actions of cyanide on membrane potential and voltage-gated ion currents in rostral ventrolateral medulla neurons in rat brainstem slices.

    PubMed

    Wang, G; Zhou, P; Repucci, M A; Golanov, E V; Reis, D J

    2001-08-24

    The present study examined specific effects of sodium cyanide (CN) on the membrane potential (MP), spontaneous discharge (SD) and voltage-gated ion current of the identified bulbospinal rostral ventrolateral medulla (RVLM) neuron in the rat pup brainstem slice. 125 microM CN rapidly depolarized MP in the RVLM neuron by 11.6 mV as well as enhanced the SD rate by 300%. In contrast, the same dose of CN immediately hyperpolarized unlabeled, non-RVLM neurons by 4.8 mV. 50 microM CN did not significantly affect voltage-gated Ca(++) or A-type K(+) currents. The same concentration of CN, however, rapidly and reversibly suppressed voltage-gated Na(+) currents and sustained outward K(+) currents in the RVLM neuron by 22.5% and 23%, respectively. Tetraethylammonium could mimic the effect of CN on MP, SD and sustained K(+) current in the RVLM neuron. It is concluded that: (1) like that from the adult rat, the rat pup bulbospinal RVLM neuron can be selectively and rapidly excited by CN; (2) the hypoxia-sensitive, sustained outward K(+) channel may play an important role in the acute hypoxia-induced excitation of the RVLM neurons. PMID:11502361

  12. Pregabalin modulation of spinal and brainstem visceral nociceptive processing.

    PubMed

    Sikandar, Shafaq; Dickenson, Anthony H

    2011-10-01

    Brainstem and spinal mechanisms mediating visceral nociception are investigated here using electrophysiology and immunohistochemistry techniques in a model of acute visceral pain. Colorectal distension (CRD) produced graded visceromotor responses (VMR) in normal rats, and these were facilitated by intracolonic mustard oil (MO) that generated acute visceral hyperalgesia. The neuropathic pain drug pregabalin (PGB) is thought to have state-dependent effects in attenuating neuropathic, but not acute somatic pain, likely by impairing calcium-channel trafficking. We found that systemic PGB produced antinociceptive effects on CRD-evoked VMRs in naïve rats lacking pathophysiology and in MO-pretreated rats. Systemic PGB also significantly reduced Fos labelling in lumbosacral spinal cords of rats given noxious repetitive CRD; however, PGB did not alter this measure of neural activity in the brainstem. Differential brainstem processing of noxious somatic and visceral stimuli may underlie the unique lack of state-dependent actions of PGB in this visceral pain model. Single-unit recordings in the rostral ventromedial medulla (RVM) verify that brainstem processing of somatic and visceral stimuli differs. The effects of CRD on RVM cells classed as ON, OFF, or NEUTRAL were independent of their somatic responses, with surprising changes in RVM cell activity to innocuous visceral stimulation. PGB also markedly reduced the visceral responses of RVM ON-cells to noxious CRD. These results illustrate clear differences in the central processing of visceral and somatic stimuli, yet a common role for descending modulation by brainstem activity in mediating evoked pain measures. PMID:21778018

  13. A brain computer interface for robust wheelchair control application based on pseudorandom code modulated Visual Evoked Potential.

    PubMed

    Mohebbi, Ali; Engelsholm, Signe K D; Puthusserypady, Sadasivan; Kjaer, Troels W; Thomsen, Carsten E; Sorensen, Helge B D

    2015-08-01

    In this pilot study, a novel and minimalistic Brain Computer Interface (BCI) based wheelchair control application was developed. The system was based on pseudorandom code modulated Visual Evoked Potentials (c-VEPs). The visual stimuli in the scheme were generated based on the Gold code, and the VEPs were recognized and classified using subject-specific algorithms. The system provided the ability of controlling a wheelchair model (LEGO(®) MINDSTORM(®) EV3 robot) in 4 different directions based on the elicited c-VEPs