Science.gov

Sample records for brainstem evoked potentials

  1. Brainstem Auditory Evoked Potential in HIV-Positive Adults

    PubMed Central

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

    2015-01-01

    Background To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. Material/Methods This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment – research groups I and II, respectively – and 30 control group individuals) were assessed through brainstem auditory evoked potential. Results There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. Conclusions HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment. PMID:26485202

  2. Brainstem auditory evoked potential in clinical hypothyroidism

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

    Goldie, W D

    1992-07-01

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

  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. Brainstem Evoked Potential in Newly Diagnosed Patients of Subclinical Hypothyroidism

    PubMed Central

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

    2015-01-01

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

  7. Relationship between latency of brainstem auditory-evoked potentials and head size in dogs.

    PubMed

    Meij, B P; Venker-van Haagen, A J; van den Brom, W E

    1992-12-01

    Cranium and brainstem dimensions were measured in 32 postmortem dog heads. Positive correlations were found between cranium length (CL) and brainstem length (BL) (r = 0.87), between cranium width (CW) and brainstem width (BW) (r = 0.83), and between cranium distance (CD = CL+CW/2) and brainstem distance (BD = BL+BW/2) (r = 0.91). Positive correlation coefficients were also found between CL and CW (r = 0.90), and between BL and BW (r = 0.85). It was concluded that head size accurately reflected brainstem size. A least squares estimation of the brainstem distance (BD) from CL and CW values was BD = 10.9 + 0.16 (CL+CW/2) (BD, CL and CW in mm). Brainstem auditory evoked potentials (BAEPs) and cranium dimensions were measured in 43 dogs (86 ears) with different head size, body size, sex and age. Wave form, absolute and interpeak latencies and correlation coefficients, relating latencies to cranium dimensions and body weight, were analysed. CL, CW, and CD were positively correlated with body weight (r = 0.93, 0.70 and 0.93, respectively), and CL, CW, and CD were correlated with age (r = 0.33, 0.52, and 0.40, respectively). BAEPs consisted of five distinct positive peaks (I to V). Secondary positive peaks following peaks I and II were seen in 60% (I') and 90% (II') of the recordings. Late waves were recorded in 90% (VI), 50% (VII), and 25% (VIII) of the recordings. Latencies increased with decreasing stimulus intensity level (from 90 dB to 10 dB hearing level, HL), especially for peaks I, II, V, and the I-V interpeak interval.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1485399

  8. Acoustically evoked potentials in two cephalopods inferred using the auditory brainstem response (ABR) approach.

    PubMed

    Hu, Marian Y; Yan, Hong Young; Chung, Wen-Sung; Shiao, Jen-Chieh; Hwang, Pung-Pung

    2009-07-01

    It is still a matter of debate whether cephalopods can detect sound frequencies above 400 Hz. So far there is no proof for the detection of underwater sound above 400 Hz via a physiological approach. The controversy of whether cephalopods have a sound detection ability above 400 Hz was tested using the auditory brainstem response (ABR) approach, which has been successfully applied in fish, crustaceans, amphibians, reptiles and birds. Using ABR we found that auditory evoked potentials can be obtained in the frequency range 400 to 1500 Hz (Sepiotheutis lessoniana) and 400 to 1000 Hz (Octopus vulgaris), respectively. The thresholds of S. lessoniana were generally lower than those of O. vulgaris. PMID:19275944

  9. Changes in brainstem auditory evoked potentials among North Indian females with Type 2 diabetes mellitus

    PubMed Central

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

    2013-01-01

    Background: Diabetes mellitus is a complex metabolic disorder whose detrimental effects on various organ systems, including the nervous system are well known. Aim: This study was conducted to determine the changes in the brainstem auditory evoked potentials (BAEP) in patients with type 2 diabetes mellitus. Materials and Methods: In this case-control study, 116 females with type 2 diabetes and 100 age matched, healthy female volunteers were selected. The brainstem auditory evoked potentials (BAEP) were recorded with RMS EMG EP Marc-II Channel machine. The measures included latencies of waves I, II, III, IV, V and Interpeak latencies (IPL) I-III, III-V and I-V separately for both ears. Data was analysed statistically with SPSS software v13.0. Results: It was found that IPL I-III was significantly delayed (P = 0.028) only in the right ear, while the latency of wave V and IPL I-V showed a significant delay bilaterally (P values for right ear being 0.021 and 0.0381 respectively while those for left ear being 0.028 and 0.016 respectively), in diabetic females. However, no significant difference (P > 0.05) was found between diabetic and control subjects as regards to the latencies of waves I, II, III, IV and IPL III-V bilaterally and IPL I-III unilaterally in the left ear. Also, none of the BAEP latencies were significantly correlated with either the duration of disease or with fasting blood glucose levels in diabetics. Conclusions: Therefore, it could be concluded that diabetes patients have an early involvement of central auditory pathway, which can be detected quite accurately with the help of auditory evoked potential studies. PMID:24381878

  10. 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

  11. Brainstem auditory and somatosensory evoked potentials: a methodological study to evaluate the reproducibility of two devices.

    PubMed

    Moncho, D; Poca, M A; Minoves, T; Ferré, A; Rahnama, K; Sahuquillo, J

    2014-12-01

    We aimed to determine whether statistical significant differences exist between the sets of results obtained from two devices used in our department for measuring brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs). We obtained BAEP and median and posterior tibial nerve SEP values bilaterally in ten healthy subjects. The tests were performed on the same subject using two devices consecutively. The equipment consisted of a Nicolet Viking-IV (Nicolet, Madison, WI, USA) and a Viking Select (Viasys Healthcare, Madison, WI, USA), and the same recording electrodes and stimulator (auditory and electrical) were used without modifying any postural position of the subject. The stimuli and recording parameters were the same for both devices. We obtained 20 sets of data for each type of test. The Bland–Altman plots as well as the one-sample t-test or Wilcoxon signed rank test were used to compare data between the two groups of data sets. We found no significant differences between the sets of values obtained with the two devices. Our analysis indicates that the two devices are equal in recording all different variables of BAEP and SEP, which allows us to combine the BAEP and SEP data obtained from the two devices for follow-up studies involving quantitative statistical methods. This study received institutional approval (protocol number PRAG-154/2013). PMID:25420133

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

    PubMed

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

    1982-12-01

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

  14. 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

  15. Mammalian CNS barosensitivity: studied by brain-stem auditory-evoked potential in mice.

    PubMed

    Chen, Ruiyong; Xiao, Weibing; Li, Jun; He, Jia; Chen, Haiting

    2012-01-01

    High pressure nervous syndrome (HPNS) is an instinctive response of mammalian high-class nervous functions to increased hydrostatic pressure. Electrophysiological activity of mammalian central nervous system (CNS), including brainstem auditory-evoked potential (BAEP), has characteristic changes under pressure. Here we recorded BAEP of 63 mice exposed to 0-4.0 MPa. The results showed that interpeak latencies between wave I and wave IV (IPL1-4) and their changes under pressures (deltaIPL1-4) responded to increasing pressure in a biphase pattern, shortened under pressure from 0 to 0.7MPa, then prolonged later. There were significantly negative correlations between base IPL1-4s and deltaIPL1-4s (p < 0.01). Individual IPL1-4s were supposed to respond to increasing pressure in a relative steady pattern in accordance with its base IPL1-4s. Those with shorter-base IPL1-4 presented direct increases in IPL1-4. However, those with longer-base IPL1-4 had a decreased IPL1-4 under small to moderate pressure then rebounded later. Our results suggested that mammalian CNS functions were susceptible to small to moderate pressure, as well as a higher pressure than 1.0MPa. Mice, as a statistical mass, had an "optimum" pressure about 0.7MPa, rather than atmospheric pressure, referred as shortest IPL1-4s. An individual's response to high pressure might be relied on his base biological condition. Our results highlighted a new approach to investigate a practical strategy to medical selecting barotolerant candidates for deep divers. Diversity of individual susceptibility to hydrostatic pressure was under discussed. Underlying mechanisms of the "optimum" pressure for CNS function and its significance to neurophysiology remain open to further exploration. PMID:22400446

  16. Comparison of brainstem reflex recordings and evoked potentials with clinical and MRI data to assess brainstem dysfunction in multiple sclerosis: a short-term follow-up.

    PubMed

    Magnano, I; Pes, G M; Cabboi, M P; Pilurzi, G; Ginatempo, F; Achene, A; Salis, A; Conti, M; Deriu, Franca

    2016-09-01

    Brainstem dysfunctions are associated to high risk of developing severe disability in patients with multiple sclerosis (PwMS), often undetected by conventional routine assessments. In this view, the purpose of this study was to monitor brainstem function over a short-term period in PwMS, comparing clinical and magnetic resonance imaging (MRI) examinations with evoked potentials (EPs) and brainstem reflexes (BSRs). Forty-five PwMS were evaluated at baseline and after 15.1 ± 4.2 months through Expanded Disability Status Scale (EDSS) score, MRI, EPs, vestibulo-masseteric (VMR), acoustic-masseteric (AMR), vestibulo-collic (VCR) and trigemino-collic (TCR) reflexes. At baseline, brainstem alterations were detected by EDSS, MRI, EPs and BSRs in 40, 77.8, 84.4 and 82.2 % of patients, respectively. At follow-up, EDSS and MRI remained unchanged, while EP and BSR deteriorated in 86.7 and 91.1 % of patients, respectively. Changes from 1 to 3 altered EPs and from 1 to 4 altered BSRs were significant only for EPs (p = 0.028). The analysis of grading severity for each test disclosed significant worsening of the VMR, AMR, TCR and P14 wave of the median somatosensory EP. Combined EP/BSR recordings were significantly more sensitive than paired EDSS/MRI assessments at baseline (93.3 versus 80 %; p = 0.006) and follow-up (97.8 versus 82.2 %; p = 0.008). In the short-term VMR, AMR, TCR and P14 wave disclosed a significant functional brainstem deterioration by detecting lesions that remained clinically and MRI silent. Our findings provide evidence for a valuable role of neurophysiological methods, especially BSRs, in investigating and monitoring brainstem dysfunctions in MS, in comparison with the standard clinical and MRI procedures. PMID:27177651

  17. Comparison of electrically evoked whole-nerve action potential and electrically evoked auditory brainstem response thresholds in nucleus CI24R cochlear implant recipients.

    PubMed

    Hay-McCutcheon, Marcia J; Brown, Carolyn J; Clay, Kelly Schmidt; Seyle, Keely

    2002-09-01

    In this study, differences between electrically evoked whole-nerve action potential (EAP) and electrically evoked auditory brainstem response (EABR) measurements within Nucleus CI24R cochlear implant recipients were evaluated. Precurved modiolus-hugging internal electrode arrays, such as the CI24R, are designed to provide more direct stimulation of neural elements of the modiolus. If the electrode array is closer to the modiolus, electrically evoked and behavioral levels might be lower than were previously recorded for the straight electrode array, the CI24M. EAP and EABR growth functions and behavioral levels were obtained for 10 postlingually deafened adults. Results revealed no significant differences between EAP and EABR threshold levels, and these levels were not significantly lower than those obtained using the CI24M. PMID:12371659

  18. [Prognostic evaluation of patients with severe head injury by motor evoked potentials induced by transcranial magnetic stimulation--combined analysis with brainstem auditory evoked potentials].

    PubMed

    Kaneko, M

    1995-05-01

    Prognostic evaluation of severe head injury was performed on the basis of transcranial magnetic motor evoked potentials (MEPs) and brainstem auditory evoked potentials (BAEPs). The subjects were 43 severe head injury patients with Glasgow Coma Scale Scores (GCS) of 9 or less. MEPs were recorded within 3 days after the injury. Patient outcome at 1, 6 and 12 months after the injury was correlated with the MEPs and BAEPs. Differences between MEP and BAEP findings in focal lesions and diffuse lesions also were analyzed. MEP wave latencies and inter-peak latencies between BAEP waves IV and V and between waves I and V were evaluated. There was a closer relationship between MEP latency and GOS, especially between the good recovery group and other outcome groups. At 1 month after the injury, there was a closer correlation between MEP latency and BAEP latency in those who died than in those who survived, and this tendency was more evident with regard to focal lesions. However, there was no significant correlation between MEP and patient outcome when the lesions were diffuse. There was no correlation between BAEP latencies and patient outcome, but there was a good, close correlation between prolonged MEP latency and unfavorable outcome at 1, 6, 12 months after injury. In conclusion, the combined use of BAEPs and MEPs induced by transcranial magnetic stimulation is useful in prognostic evaluation of acute head injury patients, especially when the brain lesions are focal. PMID:7786626

  19. The simultaneous use of electrocochleogram, brainstem auditory evoked potential and facial muscle EMG in cerebellopontine angle tumor removal.

    PubMed

    Hsu, J C; Lui, T N; Yu, C L; Chen, Y C; Chang, C N; Tan, P P

    1992-06-01

    In six cases of acoustic neurilemmoma, electrocochleogram (ECOchG), brainstem auditory evoked potentials (BAEP) and facial muscle electromyograms (EMG) were recorded to monitor facial nerve and brainstem function. Under isoflurane and nitrous oxide anesthesia, we recorded ECOchG from the tympanic membrane, BAEP from the scalp needle, and facial muscle EMG from the mentalis muscle. During surgery, the body temperature was kept above 36.5 degrees C, and PaCO2 above 30 mmHg. In all cases, the peak N1 of ECOchG and wave I of BAEP had identical latencies throughout the monitoring period. The response was faster and the amplitude was higher in the ECOchG recordings. For calculation of the I-III or I-V interpeak latency of BAEP, the wave I of BAEP could be confirmed more quickly and precisely by the peak N1 of ECOchG. During tumor removal, the embedded facial nerve pathway in the tumor was identified by electric stimulation of the intracranial facial nerve, followed by evoked facial muscle EMG. Facial nerve function was confirmed by nerve traction or direct electric stimulation after total removal of the tumor. No facial palsy or other neurologic sequelae was found after the operations. PMID:1358342

  20. A Multicentre Database for Normative Brainstem Auditory Evoked Potentials (BAEPs) in Children: Methodology for Data Collection and Evaluation

    PubMed Central

    Scaioli, Vidmer; Brinciotti, Mario; Di Capua, Matteo; Lori, Silvia; Janes, Augusta; Pastorino, Giancarlo; Peruzzi, Cinzia; Sergi, Paola; Suppiej, Agnese

    2009-01-01

    Background: The influence of physiological and methodological factors on recordings of brainstem auditory evoked potentials (BAEPs) is greater in children than in adults. Objective: To collect and evaluate BAEP data in normal children, and measure intra- and inter-laboratory variability. Methods: Seven hundred and fifty unselected BAEP recordings were collected and evaluated from children ranging from neonates to 14-year-olds by eight laboratories in Italy. Results: In newborns, three laboratories showed satisfactory concordance; wave I was more broadly distributed than wave V and IPL I-V. The evaluation of pooled BAEP data from the older children showed that laboratories with age-matched data gave overlapping results; those with unmatched-age data differed significantly. The sound intensities of the laboratories did not significantly affect absolute BAEP latencies or IPLs. Females had shorter latencies than males; the difference was not significant. A single exponential regression model was an adequate but not the best predictor of normal data. Conclusions: The pooled data were consistent with the physiological maturation of the brainstem acoustic pathway. The BAEPs was reliably normalised using the natural logarithm of age. The differences between Centres were related to sample size, measurement accuracy, and inclusion and selection criteria. Significance: The creation of multicentre common database from an unmatched data collection is feasible and reliable enough for clinical diagnosis and multicentre clinical research. PMID:19911069

  1. Three-channel Lissajous' trajectories of auditory brainstem evoked potentials: contribution of fast and slow components to planar segment formation.

    PubMed

    Pratt, H; Bleich, N; Feingold, K

    1990-01-01

    Three-Channel Lissajous' Trajectories (3CLT) of Auditory Brainstem Evoked Potentials (ABEP) to clicks were obtained after finite impulse response filtering in three frequency bands. These bands were chosen to replicate the widely used passband (100-3000 Hz) and to selectively enhance the definition of the 'pedestal' (10-240 Hz) or the first, third and fifth components (240-483 Hz). Quantitative measures of 3CLT were calculated to describe apex latencies, planar segment orientations, durations, trajectory amplitude peaks and their latencies. In addition, dipole moments at the latencies of apical points along 3-CLT were calculated. The planarity of ABEP 3-CLT segments persisted after selective enhancement of the 'pedestal' or the first, third and fifth components. These results rule out the suggestion that planarity of ABEP segments results from the interaction of the 'pedestal' with the superimposed faster components. These results demonstrate summation of 3-CLT planar segments ('a' 'c' and 'e' with the 'pedestal') to form new segments (wide-band 'a', 'c' and 'e'). With the exception of 'c', planar segments and the equivalent dipole moments associated with apexes did not change orientations across passbands. The effects of passband on the orientation of planar segment 'c' and the dipole moment of its apex are explained by its superimposition on the 'pedestal' in the wide-band records. A similar analysis of ABEP to clicks as compared to low-frequency stimuli (high-pass masked clicks) revealed no change in planarity nor in plane parameters. These results are compatible with the suggestion that the generators of the first, third and fifth ABEP components are curved fiber tracts. The planarity of the slow 'pedestal' may be due to the summation of slow synaptic potentials in auditory brainstem nuclei. These findings indicate that the generators of ABEP are composites that may be separated by selective lesion studies. PMID:2312411

  2. Abnormalities in Brainstem Auditory Evoked Potentials in Sheep with Transmissible Spongiform Encephalopathies and Lack of a Clear Pathological Relationship.

    PubMed

    Konold, Timm; Phelan, Laura J; Cawthraw, Saira; Simmons, Marion M; Chaplin, Melanie J; González, Lorenzo

    2016-01-01

    Scrapie is transmissible spongiform encephalopathy (TSE), which causes neurological signs in sheep, but confirmatory diagnosis is usually made postmortem on examination of the brain for TSE-associated markers like vacuolar changes and disease-associated prion protein (PrP(Sc)). The objective of this study was to evaluate whether testing of brainstem auditory evoked potentials (BAEPs) at two different sound levels could aid in the clinical diagnosis of TSEs in sheep naturally or experimentally infected with different TSE strains [classical and atypical scrapie and bovine spongiform encephalopathy (BSE)] and whether any BAEP abnormalities were associated with TSE-associated markers in the auditory pathways. BAEPs were recorded from 141 clinically healthy sheep of different breeds and ages that tested negative for TSEs on postmortem tests to establish a reference range and to allow comparison with 30 sheep clinically affected or exposed to classical scrapie (CS) without disease confirmation (test group 1) and 182 clinically affected sheep with disease confirmation (test group 2). Abnormal BAEPs were found in 7 sheep (23%) of group 1 and 42 sheep (23%) of group 2. The proportion of sheep with abnormalities did not appear to be influenced by TSE strain or PrP(Sc) gene polymorphisms. When the magnitude of TSE-associated markers in the auditory pathways was compared between a subset of 12 sheep with and 12 sheep without BAEP abnormalities in group 2, no significant differences in the total PrP(Sc) or vacuolation scores in the auditory pathways could be found. However, the data suggested that there was a difference in the PrP(Sc) scores depending on the TSE strain because PrP(Sc) scores were significantly higher in sheep with BAEP abnormalities infected with classical and L-type BSE, but not with CS. The results indicated that BAEPs may be abnormal in sheep infected with TSEs but the test is not specific for TSEs and that neither vacuolation nor PrP(Sc) accumulation

  3. Abnormalities in Brainstem Auditory Evoked Potentials in Sheep with Transmissible Spongiform Encephalopathies and Lack of a Clear Pathological Relationship

    PubMed Central

    Konold, Timm; Phelan, Laura J.; Cawthraw, Saira; Simmons, Marion M.; Chaplin, Melanie J.; González, Lorenzo

    2016-01-01

    Scrapie is transmissible spongiform encephalopathy (TSE), which causes neurological signs in sheep, but confirmatory diagnosis is usually made postmortem on examination of the brain for TSE-associated markers like vacuolar changes and disease-associated prion protein (PrPSc). The objective of this study was to evaluate whether testing of brainstem auditory evoked potentials (BAEPs) at two different sound levels could aid in the clinical diagnosis of TSEs in sheep naturally or experimentally infected with different TSE strains [classical and atypical scrapie and bovine spongiform encephalopathy (BSE)] and whether any BAEP abnormalities were associated with TSE-associated markers in the auditory pathways. BAEPs were recorded from 141 clinically healthy sheep of different breeds and ages that tested negative for TSEs on postmortem tests to establish a reference range and to allow comparison with 30 sheep clinically affected or exposed to classical scrapie (CS) without disease confirmation (test group 1) and 182 clinically affected sheep with disease confirmation (test group 2). Abnormal BAEPs were found in 7 sheep (23%) of group 1 and 42 sheep (23%) of group 2. The proportion of sheep with abnormalities did not appear to be influenced by TSE strain or PrPSc gene polymorphisms. When the magnitude of TSE-associated markers in the auditory pathways was compared between a subset of 12 sheep with and 12 sheep without BAEP abnormalities in group 2, no significant differences in the total PrPSc or vacuolation scores in the auditory pathways could be found. However, the data suggested that there was a difference in the PrPSc scores depending on the TSE strain because PrPSc scores were significantly higher in sheep with BAEP abnormalities infected with classical and L-type BSE, but not with CS. The results indicated that BAEPs may be abnormal in sheep infected with TSEs but the test is not specific for TSEs and that neither vacuolation nor PrPSc accumulation appears to be

  4. Rhesus macaque model of chronic opiate dependence and neuro-AIDS: longitudinal assessment of auditory brainstem responses and visual evoked potentials

    PubMed Central

    Riazi, Mariam; Marcario, Joanne K; Samson, Frank K.; Kenjale, Himanshu; Adany, Istvan; Staggs, Vincent; Ledford, Emily; Marquis, Janet; Narayan, Opendra; Cheney, Paul D.

    2013-01-01

    Our work characterizes the effects of opiate (morphine) dependence on auditory brainstem and visual evoked responses in a rhesus macaque model of neuro-AIDS utilizing a chronic continuous drug delivery paradigm. The goal of this study was to clarify whether morphine is protective, or if it exacerbates simian immunodeficiency virus (SIV) related systemic and neurological disease. Our model employs a macrophage tropic CD4/CCR5 co-receptor virus, SIVmac239 (R71/E17), which crosses the blood brain barrier shortly after inoculation and closely mimics the natural disease course of human immunodeficiency virus (HIV) infection. The cohort was divided into 3 groups: morphine only, SIV only, and SIV + morphine. Evoked potential (EP) abnormalities in sub-clinically infected macaques were evident as early as eight weeks post-inoculation. Prolongations in EP latencies were observed in SIV-infected macaques across all modalities. Animals with the highest CSF viral loads and clinical disease showed more abnormalities than those with sub-clinical disease, confirming our previous work (Raymond et al, 1998, 1999, 2000). Although some differences were observed in auditory and visual evoked potentials in morphine treated compared to untreated SIV-infected animals, the effects were relatively small and not consistent across evoked potential type. However, morphine treated animals with subclinical disease had a clear tendency toward higher virus loads in peripheral and CNS tissues (Marcario et al., 2008) suggesting that if had been possible to follow all animals to end-stage disease, a clearer pattern of evoked potential abnormality might have emerged. PMID:19283490

  5. A model for simulation of electrically evoked auditory brainstem responses

    NASA Astrophysics Data System (ADS)

    Miller, Douglas A.; Matin, Mohammed A.

    2009-08-01

    An important aspect of research in the continued development of cochlear implants is the in vivo assessment of signal processing algorithms. One technique that has been used is evoked potentials, the recording of neural responses to auditory stimulation. Depending on the latency of the observed response, the evoked potential indicates neural activity at the various neurological structures of the auditory system. Electrically evoked ABRs are commonly measured in hearing-impaired patients who have cochlear implants, via electrical stimulation delivered by electrodes in the implanted array. This research explores the use of MATLAB for the purpose of developing a model for electrically evoked auditory brainstem responses (ABRs). The simulation model developed in this study takes as its input the stimulus current intensity level, and uses function vectors and equations derived from measured ABRs, to generate an approximation of the evoked surface potentials. A function vector is used to represent the combined firing of the neurons of the auditory nervous system that are needed to elicit a measurable response. Equations have been derived to represent the latency and stimulus amplitude scaling functions. The simulation also accounts for other neural activity that can be present in and contaminate an ABR recording, and reduces it through time-locked averaging of the simulated response. In the MATLAB simulation, the model performs well and delivers results that compare favorably with the results measured from the research subjects.

  6. Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. I. Superior olivary complex.

    PubMed

    Zaaroor, M; Starr, A

    1991-01-01

    Auditory brain-stem potentials (ABRs) were studied in cats for up to 45 days after kainic acid had been injected unilaterally or bilaterally into the superior olivary complex (SOC) to produce neuronal destruction while sparing fibers of passage and the terminals of axons of extrinsic origin connecting to SOC neurons. The components of the ABR in cat were labeled by their polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents labeled P1a and P1b. The correspondences we have assumed between the ABR components in cat and man are indicated by providing a Roman numeral designation for the human component in parentheses following the feline notation, e.g., P4 (V). With bilateral SOC destruction, there was a significant and marked attenuation of waves P2 (III), P3 (IV), P4 (V), P5 (VI), and the sustained potential shift (SPS) amounting to as much as 80% of preoperative values. Following unilateral SOC destruction the attenuation of many of these same ABR components, in response to stimulation of either ear, was up to 50%. No component of the ABR was totally abolished even when the SOC was lesioned 100% bilaterally. In unilaterally lesioned cats with extensive neuronal loss (greater than 75%) the latencies of the components beginning at P3 (IV) were delayed to stimulation of the ear ipsilateral to the injection site but not to stimulation of the ear contralateral to the injection. Binaural interaction components of the ABR were affected in proportion to the attenuation of the ABR. These results are compatible with multiple brain regions contributing to the generation of the components of the ABR beginning with P2 (III) and that components P3 (IV), P4 (V), and P5 (VI) and the sustained potential shift depend particularly on the integrity of the neurons of the SOC bilaterally. The neurons of the lateral subdivision (LSO) and the medial nucleus of the trapezoid body

  7. Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. II. Cochlear nucleus.

    PubMed

    Zaaroor, M; Starr, A

    1991-01-01

    Auditory brain-stem potentials (ABRs) were studied in cats for up to 6 weeks after kainic acid had been injected unilaterally into the cochlear nucleus (CN) producing extensive neuronal destruction. The ABR components were labeled by the polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents, P1a and P1b. The assumed correspondence between the ABR components in cat and man is indicated by providing human Roman numeral designations in parentheses following the feline notation, e.g., P2 (III). To stimulation of the ear ipsilateral to the injection, the ABR changes consisted of a loss of components P2 (III) and P3 (IV), and an attenuation and prolongation of latency of components P4 (V) and P5 (VI). The sustained potential shift from which the components arose was not affected. Wave P1a (I) was also slightly but significantly attenuated compatible with changes of excitability of nerve VIII in the cochlea secondary to cochlear nucleus destruction. Unexpectedly, to stimulation of the ear contralateral to the injection side, waves P2 (III), P3 (IV), and P4 (V) were also attenuated and delayed in latency but to a lesser degree than to stimulation of the ear ipsilateral to the injection. Changes in binaural interaction of the ABR following cochlear nucleus lesions were similar to those produced in normal animals by introducing a temporal delay of the input to one ear. The results of the present set of studies using kainic acid to induce neuronal loss in auditory pathway when combined with prior lesion and recording experiments suggest that each of the components of the ABR requires the integrity of an anatomically diffuse system comprising a set of neurons, their axons, and the neurons on which they terminate. Disruption of any portion of the system will alter the amplitude and/or the latency of that component. PMID:1716569

  8. Developmental exposure to purity-controlled polychlorinated biphenyl congeners (PCB74 and PCB95) in rats: effects on brainstem auditory evoked potentials and catalepsy.

    PubMed

    Lilienthal, Hellmuth; Korkalainen, Merja; Andersson, Patrik L; Viluksela, Matti

    2015-01-01

    Whereas the effects of dioxin-like polychlorinated biphenyls (DL-PCBs) are well described, less is known about non-dioxin-like PCBs (NDL-PCBs), including influences on the nervous system and related behavioral effects after developmental exposure. Following the examination of the highly purified NDL congeners PCB52 and PCB180, we report here the results of experiments with PCB74 and PCB95. Rat dams were orally exposed to equimolar doses of either congener (40μmol/kg bw - 11.68mg PCB74/kg bw or 13.06mg PCB95/kg bw) from gestational day (GD) 10 to postnatal day (PND) 7. Control dams were given the vehicle. Adult offspring were tested for cataleptic behavior after induction with haloperidol, a classical neuroleptic drug, and brainstem auditory evoked potentials (BAEPs), using clicks and tone pips of different frequencies for stimulation. Results revealed slight effects on latencies to movement onset in female offspring exposed to PCB74, whereas PCB74 males and offspring exposed to PCB95 were not affected. Pronounced changes were observed in BAEPs at low frequencies in PCB74 offspring, with elevated thresholds in both sexes. PCB95 increased thresholds in males, but not females. Small effects were detected on latency of the late wave IV in both sexes after developmental exposure to PCB74 or PCB95. Compared with the other NDL-PCB congeners tested, PCB74 caused the most pronounced effects on BAEPs. PMID:25449634

  9. Newborn Auditory Brainstem Evoked Responses (ABRs): Prenatal and Contemporary Correlates.

    ERIC Educational Resources Information Center

    Murray, Ann D.

    1988-01-01

    Presented are a literature review and new data on correlates of newborn auditory brainstem evoked responses (ABRs). Concludes that disorders of the central components of the ABR may be more of prenatal than of postnatal origin. The I-V interval had low but reliable correlations with four of 11 Brazelton scale variables. (RH)

  10. 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…

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

    ERIC Educational Resources Information Center

    Salamy, A.

    1981-01-01

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

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

    PubMed

    Disertori, B; Ducati, A; Piazza, M

    1982-01-01

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

  13. 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...

  14. Brainstem Origins of the N18 Component of the Somatosensory Evoked Response

    PubMed Central

    Philips, M.; Kotapka, M.; Patterson, T.; Bigelow, D. C.; Zager, E.; Flamm, E. S.; Stecker, Mark

    1998-01-01

    Proposed generator sites for the N18 component of the somatosensory evoked potential (SEP) range in location from the medulla to the thalamus. Additional knowledge regarding the generators of the N18 will be important in interpreting the results of intra-operative monitoring during skull base surgery and providing the surgeon more specific information. The goal of this study was to use both intracranial electrical recording and the effects of acute brainstem ischemia in humans to further define the generators of N18. Monopolar electrodes were used to record SEP (after median nerve stimulation) from the brainstem surface in eight patients undergoing posterior fossa surgical procedures. Recordings were made from various locations, from the cervico-medullary junction to the level of the aqueduct of Sylvius. As the electrode moved rostrally on the brainstem surface, the difference in latencies between the scalp N18 potential and the electrode potential approached zero, suggesting an upper pontine-lower midbrain origin of the N18 potential. These findings were supported by the lack of change in the N18 potentials of ten patients with basilar tip aneurysms who experienced marked changes of their N20/P22 potentials during temporary occlusion of the distal basilar artery. PMID:17171048

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

    ERIC Educational Resources Information Center

    Murray, Ann D.

    1988-01-01

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

  16. 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...

  17. UNRECOGNIZED ERRORS DUE TO ANALOG FILTERING OF THE BRAIN-STEM AUDITORY EVOKED RESPONSE

    EPA Science Inventory

    The brainstem auditory evoked response (BAER) is used as a tool both in clinical evaluation and in toxicological research, where the subject is most often the laboratory rat. As in other species, interpretation of the rat BAER waveform is based on the latencies and amplitudes of ...

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

    PubMed Central

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

    1980-01-01

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

  19. 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...

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

    PubMed Central

    Hornickel, Jane; Knowles, Erica; Kraus, Nina

    2012-01-01

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

  1. Frequency specificity of chirp-evoked auditory brainstem responses

    NASA Astrophysics Data System (ADS)

    Wegner, Oliver; Dau, Torsten

    2002-03-01

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

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

    PubMed

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

    2014-09-01

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

  3. Brainstem evoked response audiometry: an investigatory tool in detecting hepatic encephalopathy in decompensated chronic liver disease.

    PubMed

    Kabali, Balasubramanian; Velayutham, Gowri; Kapali, Suresh Chander

    2014-01-01

    It is estimated that globally there is a marked increase in liver disease with reports of rising morbidity and mortality, particularly in younger age groups. Brainstem auditory evoked potential (BAEP) was recorded in 60 decompensated chronic liver disease (DCLD) subjects who fulfilled the selection criteria and compared to 60 age and gender matched healthy subjects with normal liver functions. DCLD subjects were divided into two inter groups based on presence or absence of hepatic encephalopathy (HE). Group 1 comprises of 30 subjects of grade- I HE and Group 2 included 30 subjects without hepatic encephalopathy (NHE). Absolute and interpeak wave latencies were measured. Results were analysed by student independent t- test using SPSS software 11 version. Statistical significance was tested using P value. From the present study it can be concluded that the central nervous system is involved in liver cirrhosis evidenced by an abnormal BAEP latencies parameters. This shows that there may be progressive demyelination occurring along with axonal loss or dysfunction in liver cirrhosis HE. This study suggests that periodic evaluation of cirrhotic individuals to such test will help in monitoring the progress of encephalopathy. The prime goal of this study is early diagnosis and initiation of treatment before the onset of coma can reduce the fatality rate. PMID:25508308

  4. Brainstem evoked response audiometry: an investigatory tool in detecting hepatic encephalopathy in decompensated chronic liver disease.

    PubMed

    Kabali, Balasubramanian; Velayutham, Gowri; Kapali, Suresh Chander

    2014-01-01

    It is estimated that globally there is a marked increase in liver disease with reports of rising morbidity and mortality, particularly in younger age groups. Brainstem auditory evoked potential (BAEP) was recorded in 60 decompensated chronic liver disease (DCLD) subjects who fulfilled the selection criteria and compared to 60 age and gender matched healthy subjects with normal liver functions. DCLD subjects were divided into two inter groups based on presence or absence of hepatic encephalopathy (HE). Group 1 comprises of 30 subjects of grade- I HE and Group 2 included 30 subjects without hepatic encephalopathy (NHE). Absolute and interpeak wave latencies were measured. Results were analysed by student independent t- test using SPSS software 11 version. Statistical significance was tested using P value. From the present study it can be concluded that the central nervous system is involved in liver cirrhosis evidenced by an abnormal BAEP latencies parameters. This shows that there may be progressive demyelination occurring along with axonal loss or dysfunction in liver cirrhosis HE. This study suggests that periodic evaluation of cirrhotic individuals to such test will help in monitoring the progress of encephalopathy. The prime goal of this study is early diagnosis and initiation of treatment before the onset of coma can reduce the fatality rate. PMID:25464677

  5. Changes in the auditory nerve brainstem evoked responses in a case of maple syrup urine disease.

    PubMed

    Geal-Dor, Miriam; Adelman, Cahtia; Levi, Haya; Goitein, Kalman; Sohmer, Haim

    2004-03-01

    Maple syrup urine disease (MSUD) is a rare metabolic disease due to deficiency in the enzyme that breaks down branched chain amino acids. Lack of the enzyme causes accumulation of these amino acids and, if untreated, causes severe neurological damage. A case study of a 10-day old female infant, born after 40 weeks' gestation with a birthweight of 2740 g with MSUD hospitalized in the acute stage with respiratory failure and severe brain oedema is described. As part of the neurological evaluation, auditory nerve brainstem evoked response testing was conducted and revealed bilateral presence of the first wave from the auditory nerve, with no later brainstem waves. Over the course of days when her condition improved following dialysis treatment and a diet to reach balanced levels of branched chain amino acids, the later brainstem waves appeared on one side, and several weeks later they were also observed on the other side. The possible mechanisms of the reversibility of the appearance of brainstem waves in this case are discussed. PMID:14995088

  6. 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

  7. Electrically-evoked frequency-following response (EFFR) in the auditory brainstem of guinea pigs.

    PubMed

    He, Wenxin; Ding, Xiuyong; 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

  8. 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.

  9. Continued Maturation of the Click-Evoked Auditory Brainstem Response in Preschoolers

    PubMed Central

    Spitzer, Emily; White-Schwoch, Travis; Carr, Kali Woodruff; Skoe, Erika; Kraus, Nina

    2016-01-01

    Background Click-evoked auditory brainstem responses (ABRs) are a valuable tool for probing auditory system function and development. Although it has long been thought that the human auditory brainstem is fully mature by age 2 yr, recent evidence indicates a prolonged developmental trajectory. Purpose The purpose of this study was to determine the time course of ABR maturation in a preschool population and fill a gap in the knowledge of development. Research Design Using a cross-sectional design, we investigated the effect of age on absolute latencies, interwave latencies, and amplitudes (waves I, III, V) of the click-evoked ABR. Study Sample A total of 71 preschoolers (ages 3.12–4.99 yr) participated in the study. All had normal peripheral auditory function and IQ. Data Collection and Analysis ABRs to a rarefaction click stimulus presented at 31/sec and 80 dB SPL (73 dB nHL) were recorded monaurally using clinically-standard recording and filtering procedures while the participant sat watching a movie. Absolute latencies, interwave latencies, and amplitudes were then correlated to age. Results Developmental changes were restricted to absolute latencies. Wave V latency decreased significantly with age, whereas wave I and III latencies remained stable, even in this restricted age range. Conclusions The ABR does not remain static after age 2 yr, as seen by a systematic decrease in wave V latency between ages 3 and 5 yr. This finding suggests that the human brainstem has a continued developmental time course during the preschool years. Latency changes in the age 3–5 yr range should be considered when using ABRs as a metric of hearing health. PMID:25597458

  10. 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.

  11. 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.

  12. Are speech-evoked auditory brainstem response (speech-ABR) outcomes influenced by ethnicity?

    PubMed

    Zakaria, Mohd Normani; Jalaei, Bahram; Aw, Cheu Lih; Sidek, Dinsuhaimi

    2016-06-01

    Due to its objective nature, auditory brainstem response (ABR) evoked by complex stimuli has been gaining attention lately. The present study aimed to compare the speech-evoked auditory brainstem response (speech-ABR) results between two ethnic groups: Malay and Chinese. In addition, it was also of interest to compare the speech-ABR outcomes obtained from the present study with the published Caucasian data. Thirty healthy male adults (15 Malay and 15 Chinese) were enrolled in this comparative study. Speech syllable/da/presented at 80 dBnHL was used to record speech-ABR waveforms from the right ear of each subject. Amplitudes and latencies of speech-ABR peaks (V, A, C, D, E, F and O), as well as composite onset measures (V/A duration, V/A amplitude and V/A slope) were computed and analyzed. When the two ethnic groups were compared, all speech-ABR results were not statistically different from each other (p > 0.05). When the data from the present study were compared with the published Caucasian data, most of the statistical analyses were significant (p < 0.05). That is, Asian subjects revealed significantly higher peak amplitudes, earlier peak latencies, higher V/A amplitudes and steeper V/A slopes than that of Caucasians. The speech-ABR results between Malay and Chinese were found to be essentially similar due to anatomical similarities. Nevertheless, specific normative data for Asian adults are required as their speech-ABR results are different from that of Caucasian males. This issue should be addressed before it can be applied holistically in multiracial countries. PMID:26921173

  13. Dexmedetomidine infusion and somatosensory evoked potentials.

    PubMed

    Bloom, M; Beric, A; Bekker, A

    2001-10-01

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

  14. 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...

  15. [The disposing techniques of evoked potentials].

    PubMed

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

    2000-11-01

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

  16. 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

  17. Saturation diving with heliox to 350 meters. Observation on hearing threshold, brainstem evoked response and acoustic impedance.

    PubMed

    Wang, L; Jiang, W; Gong, J H; Zheng, X Y

    1994-12-01

    Four divers were compressed to 350 m to observe changes in hearing threshold, brainstem evoked response and acoustic impedance. The divers experienced no tinnitus, impairment of hearing, earache during compression. Examination showed that the threshold of lower frequency range of hearing was elevated because of the masking effect of the noise in the hyperbaric chamber. Changes in waveform and latency of brainstem evoked response were due to changes in sound wave transmission affected by the chamber pressure and a poor ratio of signal to noise in the hyperbaric environment with heliox. All these changes were transient. After leaving the chamber, the hearing threshold and brainstem evoked response returned to normal. Besides, there were no changes in tympanogram, acoustic compliance and stapedius reflex before and after diving. This indicated the designed speed of compression and decompression in the experiment caused no damage to the divers' acoustic system, and the functions of their Eustachain tubes, middle and inner ears were normal during the diving test. PMID:7882734

  18. Canine brainstem auditory evoked responses are not clinically impacted by head size or breed.

    PubMed

    Kemper, Debra L; Scheifele, Peter M; Clark, John Greer

    2013-02-17

    Accurate assessment of canine hearing is essential to decrease the incidence of hereditary deafness in predisposed breeds and to substantiate hearing acuity. The Brainstem Auditory Evoked Response (BAER) is a widely accepted, objective test used in humans and animals for estimation of hearing thresholds and deafness diagnosis. In contrast to humans, testing and recording parameters for determination of normal values for canine hearing are not available. Conflicting information concerning breed and head size effects on canine BAER tests are major contributors preventing this normalization. The present study utilized standard head measurement techniques coupled with BAER testing and recording parameters modeled from humans to examine the effect canine head size and breed have on BAER results. Forty-three adult dogs from fourteen different breeds had head size measurements and BAER tests performed. The mean latencies compared by breed for waves I, II, III, IV, and V were as follows: 1.46±0.49 ms, 2.52±0.54 ms, 3.45±0.41 ms, 4.53±0.83 ms and 5.53±0.43 ms, respectively. The mean wave I-V latency interval for all breeds was 3.69 ms. All dogs showed similar waveform morphology, structures, including the presence of five waves occurring within 11 ms after stimulus presentation and a significant trough occurring after Wave V. All of the waveform morphology for our subjects occurred with consistent interpeak latencies as shown by statistical testing. All animals had diagnostic results within the expected ranges for each wave latency and interwave interval allowing diagnostic evaluation. Our results establish that neither differences in head size nor breed impact determination of canine BAER waveform morphology, latency, or hearing sensitivity for diagnostic purposes. The differences in canine head size do not have a relevant impact on canine BAERs and are not clinically pertinent to management or diagnostic decisions. PMID:23262145

  19. 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.

  20. SENSORY EVOKED POTENTIALS: MEASURES OF NEUROTOXICITY

    EPA Science Inventory

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

  1. 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.

  2. Cortical auditory evoked potentials in the assessment of auditory neuropathy: two case studies.

    PubMed

    Pearce, Wendy; Golding, Maryanne; Dillon, Harvey

    2007-05-01

    Infants with auditory neuropathy and possible hearing impairment are being identified at very young ages through the implementation of hearing screening programs. The diagnosis is commonly based on evidence of normal cochlear function but abnormal brainstem function. This lack of normal brainstem function is highly problematic when prescribing amplification in young infants because prescriptive formulae require the input of hearing thresholds that are normally estimated from auditory brainstem responses to tonal stimuli. Without this information, there is great uncertainty surrounding the final fitting. Cortical auditory evoked potentials may, however, still be evident and reliably recorded to speech stimuli presented at conversational levels. The case studies of two infants are presented that demonstrate how these higher order electrophysiological responses may be utilized in the audiological management of some infants with auditory neuropathy. PMID:17715648

  3. Spinal evoked potentials following transcranial magnetic stimulation.

    PubMed

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

    2001-06-01

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

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

    PubMed

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

    1985-12-01

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

  5. Lateralization and Binaural Interaction of Middle-Latency and Late-Brainstem Components of the Auditory Evoked Response.

    PubMed

    Dykstra, Andrew R; Burchard, Daniel; Starzynski, Christian; Riedel, Helmut; Rupp, Andre; Gutschalk, Alexander

    2016-08-01

    We used magnetoencephalography to examine lateralization and binaural interaction of the middle-latency and late-brainstem components of the auditory evoked response (the MLR and SN10, respectively). Click stimuli were presented either monaurally, or binaurally with left- or right-leading interaural time differences (ITDs). While early MLR components, including the N19 and P30, were larger for monaural stimuli presented contralaterally (by approximately 30 and 36 % in the left and right hemispheres, respectively), later components, including the N40 and P50, were larger ipsilaterally. In contrast, MLRs elicited by binaural clicks with left- or right-leading ITDs did not differ. Depending on filter settings, weak binaural interaction could be observed as early as the P13 but was clearly much larger for later components, beginning at the P30, indicating some degree of binaural linearity up to early stages of cortical processing. The SN10, an obscure late-brainstem component, was observed consistently in individuals and showed linear binaural additivity. The results indicate that while the MLR is lateralized in response to monaural stimuli-and not ITDs-this lateralization reverses from primarily contralateral to primarily ipsilateral as early as 40 ms post stimulus and is never as large as that seen with fMRI. PMID:27197812

  6. Pattern visual evoked potentials in hyperthyroidism.

    PubMed Central

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

    1988-01-01

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

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

    PubMed

    Strenge, H

    1986-06-01

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

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

    PubMed

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

    1995-01-01

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

  9. 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.

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

    PubMed

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

    2010-11-30

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

  11. 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

  12. Analysis of evoked lumbosacral potentials in man.

    PubMed

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

    1978-04-01

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

  13. 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

  14. Conditions for evoked-potential audiometry in odontocetes

    NASA Astrophysics Data System (ADS)

    Supin, Alexander Ya.

    2005-04-01

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

  15. Acoustic Responses after Total Destruction of the Cochlear Receptor: Brainstem and Auditory Cortex

    NASA Astrophysics Data System (ADS)

    Cazals, Yves; Aran, Jean-Marie; Erre, Jean-Paul; Guilhaume, Anne

    1980-10-01

    Acoustically evoked neural activity has been recorded from the brainstem and auditory cortex of guinea pigs after complete destruction of the organ of Corti by the aminoglycosidic antibiotic amikacin. These responses to sound differ in important respects from the evoked potentials normally recorded from the auditory pathways. At the brainstem level they resemble the potentials reported by others after stimulation of the vestibular nerve.

  16. Site-specific postural and locomotor changes evoked in awake, freely moving intact cats by stimulating the brainstem.

    PubMed

    Mori, S; Sakamoto, T; Ohta, Y; Takakusaki, K; Matsuyama, K

    1989-12-25

    Locomotor behaviors evoked by stimulating the hypothalamus and the brainstem were studied in freely moving, awake cats. To do this, stimulating microelectrodes were chronically implanted into the subthalamic locomotor region (SLR) in the lateral hypothalamic area (LHA), the mesencephalic locomotor region (MLR) corresponding to the nucleus cuneiformis, the dorsal tegmental field (DTF) and the ventral tegmental field (VTF) of caudal pons along its midline. After recovery from surgery (2-3 days), open field tests were performed to study stimulus effects upon posture and locomotor movements. The stimuli consisted of pulses of 0.2 ms duration of less than 80 microA delivered at 50 pulses/s for 5-20 s. DTF stimulation resulted in suppression of postural support by the hindlimbs. When the cat was in a standing posture, DTF stimulation simply resulted in a sequential alteration of posture to a squatting and then to a final lying posture. In contrast, VTF stimulation evoked an almost opposite series of postural changes to those induced by DTF stimulation. With VTF stimulation, the cat changed from a lying or a squatting position, and then started to walk during continuation of the stimulation. With MLR stimulation, the cat invariably exhibited fast walking and then running movements. It ran straight forward, avoiding collision with walls or other obstacles, and even tried to jump over a fence placed in front of it. With LHA stimulation, the cat started to walk slowly extending its head forward and looking around repeatedly. It tended to walk with a stoop and stealthy steps along the corners of the room. Induced postural and locomotor changes were always accompanied by behavioral arousal reactions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2611678

  17. 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

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

    PubMed

    Strenge, H

    1989-09-01

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

  19. [Somatosensory evoked potentials in moderate hyperthermia].

    PubMed

    Strenge, H

    1991-09-01

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

  20. [Auditory evoked potentials under attentional lapses].

    PubMed

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

    2014-01-01

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

  1. 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.

  2. 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

  3. Auditory- and Visual-Evoked Potentials in Mexican Infants Are Not Affected by Maternal Supplementation with 400 mg/d Docosahexaenoic Acid in the Second Half of Pregnancy1234

    PubMed Central

    Stein, Aryeh D.; Wang, Meng; Rivera, Juan A.; Martorell, Reynaldo; Ramakrishnan, Usha

    2012-01-01

    The evidence relating prenatal supplementation with DHA to offspring neurological development is limited. We investigated the effect of prenatal DHA supplementation on infant brainstem auditory-evoked responses and visual- evoked potentials in a double-blind, randomized controlled trial in Cuernavaca, Mexico. Pregnant women were supplemented daily with 400 mg DHA or placebo from gestation wk 18–22 through delivery. DHA and placebo groups did not differ in maternal characteristics at randomization or infant characteristics at birth. Brainstem auditory-evoked responses were measured at 1 and 3 mo in 749 and 664 infants, respectively, and visual-evoked potentials were measured at 3 and 6 mo in 679 and 817 infants, respectively. Left-right brainstem auditory-evoked potentials were moderately correlated (range, 0.26–0.43; all P < 0.001) and left-right visual-evoked potentials were strongly correlated (range, 0.79–0.94; all P < 0.001) within any assessment. Correlations across visits were modest to moderate (range, 0.09–0.38; all P < 0.01). The offspring of DHA-supplemented women did not differ from those of control women with respect to any outcome measure (all comparisons P > 0.10). We conclude that DHA supplementation during pregnancy did not influence brainstem auditory-evoked responses at 1 and 3 mo or visual-evoked potentials at 3 and 6 mo. PMID:22739364

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

    PubMed

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

    2014-01-01

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

  5. Auditory and somatosensory evoked potentials in a case of "locked-in" syndrome: a clinical and pathological study.

    PubMed

    Soria, E; Fine, E; Hajdu, I

    1989-01-01

    Brainstem auditory evoked potentials were bilaterally normal, and somatosensory evoked potentials were unilaterally abnormal in a patient with a large pontine infarct causing a "locked-in" syndrome. In the post mortem examination, the lesion extended unilaterally into the pontine tegmentum, partially involving the left medial lemniscus. The P14 potential was absent and the N20 potential was diminished in amplitude with right median nerve stimulation. The origin of the P14 potential has been debated in the literature. This case provides evidence for the P14 generator being located at the pontine level, in relation to a lemniscal area above the decussation of the somatosensory pathway. Evoked potentials can help to determine the tegmental extension of the pontine infarcts in the "locked-in" syndrome, especially in patients unable to cooperate with clinical examination. PMID:2666101

  6. Auditory evoked potential measurements with cetaceans

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  7. 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

  8. 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.

  9. 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).

  10. Limitations in the rapid extraction of evoked potentials using parametric modeling.

    PubMed

    De Silva, A C; Sinclair, N C; Liley, D T J

    2012-05-01

    The rapid extraction of variations in evoked potentials (EPs) is of great clinical importance. Parametric modeling using autoregression with an exogenous input (ARX) and robust evoked potential estimator (REPE) are commonly used methods for extracting EPs over the conventional moving time average. However, a systematic study of the efficacy of these methods, using known synthetic EPs, has not been performed. Therefore, the current study evaluates the restrictions of these methods in the presence of known and systematic variations in EP component latency and signal-to-noise ratios (SNR). In the context of rapid extraction, variations of wave V of the auditory brainstem in response to stimulus intensity were considered. While the REPE methods were better able to recover the simulated model of the EP, morphology and the latency of the ARX-estimated EPs was a closer match to the actual EP than than that of the REPE-estimated EPs. We, therefore, concluded that ARX rapid extraction would perform better with regards to the rapid tracking of latency variations. By tracking simulated and empirically induced latency variations, we conclude that rapid EP extraction using ARX modeling is only capable of extracting latency variations of an EP in relatively high SNRs and, therefore, should be used with caution in low-noise environments. In particular, it is not a suitable method for the rapid extraction of early EP components such as the auditory brainstem potential. PMID:22394572

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

    PubMed

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

    2014-10-01

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

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

    PubMed

    Buchner, H; Ferbert, A

    2016-02-01

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

  13. 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

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

    PubMed

    Finneran, James J

    2009-07-01

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

  15. 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.

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

    PubMed

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

    1995-10-01

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

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

    PubMed

    Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

    2010-05-01

    In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213-2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obtained from derived compound band action potentials provided by Eggermont [(1979). J. Acoust. Soc. Am. 65, 463-470]. CAPs were recorded from an electrode placed on the tympanic membrane (TM), and the acoustic signals were monitored with a probe tube microphone attached to the TM electrode. Results showed that the amplitude and latency of chirp-evoked N1 of the CAP differed from click-evoked CAPs in several regards. For the chirp-evoked CAP, the N1 amplitude was significantly larger than the click-evoked N1s. The latency-intensity function was significantly shallower for chirp-evoked CAPs as compared to click-evoked CAPs. This suggests that auditory nerve fibers respond with more unison to a chirp stimulus than to a click stimulus. PMID:21117748

  18. 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

  19. 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

  20. 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...

  1. 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...

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

    PubMed

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

    2011-09-01

    The initiation of the pharyngeal stage of swallowing is dependent upon sensory input to the brainstem and cortex. The event-related evoked potential provides a measure of neuronal electrical activity as it relates to a specific stimulus. Air-puff stimulation to the posterior pharyngeal wall produces a sensory-evoked potential (PSEP) waveform. The goal of this study was to characterize the scalp topography and morphology for the component peaks of the PSEP waveform. Twenty-five healthy men and women served as research participants. PSEPs were measured via a 32-electrode cap (10-20 system) connected to SynAmps2 Neuroscan EEG System. Air puffs were delivered directly to the oropharynx using a thin polyethylene tube connected to a flexible laryngoscope. The PSEP waveform is characterized by four early- and mid-latency component peaks: an early positivity (P1) and negativity (N1), followed by a mid-latency positivity (P2) and negativity (N2). The early positive peak P1 is localized bilaterally to the lateral parietal scalp, the N1 medially in the frontoparietal region, and the P2 and N2 with diffuse scalp locations. Somatosensory and premotor regions are possible anatomical correlates of peak locations. Based on the latencies of the peaks, they are likely analogous to somatosensory- and respiratory-related evoked potential peaks. PMID:20890713

  3. [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

  4. 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

  5. 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.

  6. Stimulator with arbitrary waveform for auditory evoked potentials

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

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

  7. [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

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

    PubMed

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

    1987-03-01

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

  9. 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...

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

    PubMed

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

    2012-02-01

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

  11. CO2-evoked release of PGE2 modulates sighs and inspiration as demonstrated in brainstem organotypic culture

    PubMed Central

    Forsberg, David; Horn, Zachi; Tserga, Evangelia; Smedler, Erik; Silberberg, Gilad; Shvarev, Yuri; Kaila, Kai; Uhlén, Per; Herlenius, Eric

    2016-01-01

    Inflammation-induced release of prostaglandin E2 (PGE2) changes breathing patterns and the response to CO2 levels. This may have fatal consequences in newborn babies and result in sudden infant death. To elucidate the underlying mechanisms, we present a novel breathing brainstem organotypic culture that generates rhythmic neural network and motor activity for 3 weeks. We show that increased CO2 elicits a gap junction-dependent release of PGE2. This alters neural network activity in the preBötzinger rhythm-generating complex and in the chemosensitive brainstem respiratory regions, thereby increasing sigh frequency and the depth of inspiration. We used mice lacking eicosanoid prostanoid 3 receptors (EP3R), breathing brainstem organotypic slices and optogenetic inhibition of EP3R+/+ cells to demonstrate that the EP3R is important for the ventilatory response to hypercapnia. Our study identifies a novel pathway linking the inflammatory and respiratory systems, with implications for inspiration and sighs throughout life, and the ability to autoresuscitate when breathing fails. DOI: http://dx.doi.org/10.7554/eLife.14170.001 PMID:27377173

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

    PubMed

    Tsutsui, J; Ichihashi, K; Kimura, H

    1984-01-01

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

  13. 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

  14. 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.

  15. 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

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  17. Magnetic motor evoked potentials in ponies.

    PubMed

    Mayhew, I G; Washbourne, J R

    1996-01-01

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

  18. 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…

  19. 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 ...

  20. 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…

  1. COMPARABILITY OF RAT AND HUMAN VISUAL EVOKED POTENTIALS

    EPA Science Inventory

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

  2. 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

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

    PubMed

    Stenager, E; Jensen, K

    1990-10-01

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

  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. 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

  6. A portable system for marine mammal auditory-evoked potential measurements

    NASA Astrophysics Data System (ADS)

    Finneran, James J.; Houser, Dorian S.

    2001-05-01

    Limitations to behavioral measures of hearing sensitivity in marine mammals include the time and expense typically required to train subjects. These limitations have resulted in limited subjects and lingering questions regarding intraspecific variability. An alternative to behavioral methods is the electrophysiological method, where passive electrodes are used to measure auditory-evoked potentials (AEPs) generated by the brain in response to sound stimuli. Marine mammal AEP measurements have been limited by the complexity of the technique and the limited applicability of commercially available AEP systems. In this paper, a portable, laptop computer-based system for marine mammal AEP measurements will be presented. The system features commercial off-the-shelf components, including a data acquisition PC card, biopotential amplifier, and programmable attenuator. The system is housed in a rugged, shock-resistant case. Custom software is used to present sound stimuli, record evoked responses, and analyze the resulting data. The system has been used to measure auditory brainstem responses to clicks and tone pips and envelope following responses to amplitude-modulated tones in bottlenose dolphins. Preliminary data obtained with the system will be presented and compared to behavioral hearing measures. [Work supported by the ILIR at SPAWARSYSCEN-SD and the ONR.

  7. 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

  8. 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

  9. Reversible visual evoked potential abnormalities in uremic children.

    PubMed

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

    2012-06-01

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

  10. 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.

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

    PubMed Central

    Srebro, R

    1984-01-01

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

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

    PubMed

    Domzał, T; Marks, E; Miszczak, J

    1978-01-01

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

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

    PubMed

    Wit, H P; Dijkgraaf, E

    1985-01-01

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

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

    PubMed

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

    1995-03-01

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

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

    PubMed

    Grosprêtre, Sidney; Martin, Alain

    2014-12-01

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

  16. 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.

  17. 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

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

    PubMed

    Koht, Antoun; Sloan, Tod B

    2016-09-01

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

  19. 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.

  20. 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

  1. Serotonin potentiates sympathetic responses evoked by spinal NMDA

    PubMed Central

    Madden, Christopher J; Morrison, Shaun F

    2006-01-01

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

  2. 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

  3. Using evoked potentials to match interaural electrode pairs with bilateral cochlear implants.

    PubMed

    Smith, Zachary M; Delgutte, Bertrand

    2007-03-01

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

  4. 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

  5. Transcranial Motor Evoked Potentials of Lower Limbs Can Prognosticate Ambulation in Hemiplegic Stroke Patients

    PubMed Central

    2016-01-01

    Objective To examine the association between motor evoked potentials (MEPs) in lower limbs and ambulatory outcomes of hemiplegic stroke patients. Methods Medical records of hemiplegic patients with the first ever stroke who received inpatient rehabilitation from January 2013 to May 2014 were reviewed. Patient who had diabetes, quadriplegia, bilateral lesion, brainstem lesion, severe musculoskeletal problem, and old age over 80 years were excluded. MEPs in lower limbs were measured when they were transferred to the Department of Rehabilitation Medicine. Subjects were categorized into three groups (normal, abnormal, and absent response) according to MEPs findings. Berg Balance Scale (BBS) and Functional Ambulation Category (FAC) at initial and discharge were compared among the three groups by one-way analysis of variance (ANOVA). Correlation was determined using a linear regression model. Results Fifty-eight hemiplegic patients were included. BBS and FAC at discharge were significantly (ANOVA, p<0.001) different according to MEPs findings. In linear regression model of BBS and FAC using stepwise selection, patients' age (p<0.01), BBS at admission (p<0.01), and MEPs (p<0.01) remained significant covariates. In regression assumption model of BBS and FAC at admission, MEPs and gender were significant covariates. Conclusion Initial MEPs of lower limbs can prognosticate the ambulatory outcomes of hemiplegic patients. PMID:27446774

  6. Detection of temporal gaps in noise in dolphins: evoked-potential study.

    PubMed

    Popov, V V; Supin AYa

    1997-08-01

    Temporal resolution of hearing was studied in bottlenosed dolphins by recording the auditory brain-stem response (ABR) evoked by gap in noise. Gaps shorter than 0.5 ms evoked a response combining both off- and on-components; longer gaps evoked separate off- and on-responses. Both the response to a short gap and on-response to the end of a long gap increased with increasing gap duration. On-response recovered completely at gap duration of 5-10 ms. Small but detectable response arose at gap duration as short as 0.1 ms. Contrary to the on-response after a long silence, the response to a short gap was less dependent on noise intensity. From these data, the temporal transfer function of the supposed integrator was derived assuming nonlinear transform of the integrator output to ABR amplitude. Equivalent rectangular duration of the found temporal transfer function was 0.27 ms. PMID:9265761

  7. 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...

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

    PubMed

    Wu, Zhenghua; Yao, Dezhong

    2008-10-01

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

  9. The brain-stem auditory-evoked response in the big brown bat (Eptesicus fuscus) to clicks and frequency-modulated sweeps.

    PubMed

    Burkard, R; Moss, C F

    1994-08-01

    Three experiments were performed to evaluate the effects of stimulus level on the brain-stem auditory-evoked response (BAER) in the big brown bat (Eptesicus fuscus), a species that uses frequency-modulated (FM) sonar sounds for echolocation. In experiment 1, the effects of click level on the BAER were investigated. Clicks were presented at levels of 30 to 90 dB pSPL in 10-dB steps. Each animal responded reliably to clicks at levels of 50 dB pSPL and above, showing a BAER containing four peaks in the first 3-4 ms from click onset (waves i-iv). With increasing click level, BAER peak amplitude increased and peak latency decreased. A decrease in the i-iv interval also occurred with increasing click level. In experiment 2, stimuli were 1-ms linear FM sweeps, decreasing in frequency from 100 to 20 kHz. Stimulus levels ranged from 20 to 90 dB pSPL. BAERs to FM sweeps were observed in all animals for levels of 40 dB pSPL and above. These responses were similar to the click-evoked BAER in waveform morphology, with the notable exception of an additional peak observed at the higher levels of FM sweeps. This peak (wave ia) occurred prior to the first wave seen at lower levels (wave ib). As the level of the FM sweep increased, there was a decrease in peak latency and an increase in peak amplitude. Similarity in the magnitude and behavior of the i-iv and ib-iv intervals suggests that wave ib to FM sweeps is the homolog of the wave i response to click stimuli. Experiment 3 tested the hypothesis that wave ia represented activity emanating from more basal cochlear regions than wave ib. FM sweeps (100-20 kHz) were presented at 90 dB pSPL, and broadband noise was raised in level until the BAER was eliminated. This "masked threshold" occurred at 85 dB SPL of noise. At masked threshold, the broadband noise was steeply high-pass filtered at five cutoff frequencies ranging from 20 to 80 kHz. Generally, wave ia was eliminated for masker cutoff frequencies of 56.6 kHz and below, while wave

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

    PubMed

    Strenge, H; Gundel, A

    1983-01-01

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

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

    PubMed Central

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

    1989-01-01

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

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

    PubMed

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

    1993-06-01

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

  13. 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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

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

    PubMed

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

    2008-01-01

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

  17. 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

  18. Respiratory-Related Evoked Potentials During Sleep in Children

    PubMed Central

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

    2008-01-01

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

  19. Visual Evoked Potentials: Normative Values and Gender Differences

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Tackmann, W; Ettlin, T; Strenge, H

    1982-01-01

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

  1. 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

  2. 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

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

    PubMed

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

    1997-03-01

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

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

    PubMed

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

    2014-01-01

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

  5. BAER - brainstem auditory evoked response

    MedlinePlus

    ... be a sign of hearing loss , multiple sclerosis , acoustic neuroma , or stroke. Abnormal results may also be ... PA: Butterworth-Heinemann; 2012:chap 32A. Read More Acoustic neuroma Central pontine myelinolysis Hearing loss Multiple sclerosis ...

  6. Anesthetic effects on motor evoked potentials in dogs.

    PubMed

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

    1993-06-15

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

  7. Optic nerve evoked potentials elicited by electrical stimulation.

    PubMed

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

    2005-07-01

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

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

    PubMed

    Berić, A

    1992-01-01

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

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

    PubMed

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

    2016-01-01

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

  10. 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

  11. Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders.

    PubMed

    Venhovens, J; Meulstee, J; Verhagen, W I M

    2016-01-01

    Several types of acoustic stimulation (i.e. tone bursts or clicks), bone-conducted vibration, forehead taps, and galvanic stimulation elicit myogenic potentials. These can be recorded in cervical and ocular muscles, the so called vestibular evoked myogenic potentials (VEMPs). The cervical VEMP (cVEMP) resembles the vestibulo-collic reflex and the responses can be recorded from the ipsilateral sternocleidomastoid muscle. The ocular VEMP resembles the vestibulo-ocular reflex and can be recorded from extra-ocular muscles by a surface electrode beneath the contralateral infraorbital margin. Initially, the literature concerning VEMPs was limited to peripheral vestibular disorders, however, the field of VEMP testing is rapidly expanding, with an increasing focus on central neurological disorders. The current literature concerning VEMP abnormalities in central neurological disorders is critically reviewed, especially regarding the methodological aspects in relation to quality as well as the clinical interpretation of the VEMP results. Suggestions for further research are proposed as well as some clinically useful indications. PMID:25649969

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

    Richards, A K; Hamilton-Bruce, M A

    1994-09-01

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

  14. Contrast Sensitivity versus Visual Evoked Potentials in Multiple Sclerosis

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2014-05-01

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

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

    PubMed

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

    2007-04-01

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

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

    PubMed

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

    1983-01-01

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

  19. 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

  20. Flash visual evoked potentials in diurnal birds of prey

    PubMed Central

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

    2016-01-01

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

  1. 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

  2. Pattern Visual Evoked Potentials in Dyslexic versus Normal Children

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2004-01-01

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

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

    PubMed

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

    2016-08-01

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

  5. 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

  6. 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.

  7. [Brain stem auditory and visual evoked potentials in children and adolescents with Guillain-Barré syndrome].

    PubMed

    Zgorzalewicz, Małgorzata; Zielińska, Mariola; Kilarski, Dariusz

    2004-01-01

    Guillain-Barré syndrome (GBS) is the most common acquired polyradiculoneuropathy in childhood. It has been conventionally regarded as a disease exclusively of the peripheral nervous system. The involvement of the central nervous system (CNS) in patients with GBS has been rarely described. The purpose of the study was to delineate the extent of subclinical neurological changes of CNS in children and adolescents with this syndrome. Thirty patients aged 8-18 years with GBS were treated in the Chair and Department of Developmental Neurology. The upper and lower limbs paresis dominated in clinical pictures of these patients. Cranial nerve involvement was noticed in 9 children. An ascending bulbar paralysis was noted in four cases. Sensory symptoms were found in all children. The nerve conduction velocities were abnormal in all examined patients with GBS. The control group for neurophysiological studies consisted of 66 healthy children and adolescents at the matched age. Evoked potentials (EP) were registered by means of Multiliner (Toennies, Germany). Brainstem evoked potentials (BAEP) and visual evoked potentials (VEP) were always performed in the same conditions with the same equipment for the children and adolescents in the GBS and control group, according to the guidelines of the International Federation of Clinical Neurophysiology (IFCN). The following BAEP parameters were considered: the latencies of waves I to V, interpeak latencies I-III, III-V and I-V. The latencies of N75, P100, N145 as well as the amplitudes of N75/P100, P100/N145 for mono- and binocular stimulations of VEP were analysed. BAEP showed abnormalities in 6 cases and VEP in 5 cases. The statistically significant prolongation of the latencies of waves III, V and interpeak I-V were found in children and adolescents with GBS. The BAEP changes may reflect impairment at the brainstem level in these patients. In VEP recording in GBS the prolongation of latencies P100 and N145 without changes in

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

    EPA Science Inventory

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

  9. 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

  10. 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

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

    PubMed

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

    1992-10-01

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

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

    PubMed

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

    2016-08-01

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

  13. 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

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

    PubMed

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

    1994-03-01

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

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

    PubMed Central

    Herdman, Anthony T.; Takai, Osamu

    2013-01-01

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

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

    PubMed

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

    2016-06-01

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

  17. Measurement of evoked potentials during thalamic deep brain stimulation

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    1982-01-01

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

  19. 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

  20. 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

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

    PubMed

    Strenge, H

    1990-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  3. 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

  4. 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...

  5. 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 ...

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

    PubMed Central

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

    2013-01-01

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

  7. 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.

  8. Assessing auditory evoked potentials of wild harbor porpoises (Phocoena phocoena).

    PubMed

    Ruser, Andreas; Dähne, Michael; van Neer, Abbo; Lucke, Klaus; Sundermeyer, Janne; Siebert, Ursula; Houser, Dorian S; Finneran, James J; Everaarts, Eligius; Meerbeek, Jolanda; Dietz, Rune; Sveegaard, Signe; Teilmann, Jonas

    2016-07-01

    Testing the hearing abilities of marine mammals under water is a challenging task. Sample sizes are usually low, thus limiting the ability to generalize findings of susceptibility towards noise influences. A method to measure harbor porpoise hearing thresholds in situ in outdoor conditions using auditory steady state responses of the brainstem was developed and tested. The method was used on 15 live-stranded animals from the North Sea during rehabilitation, shortly before release into the wild, and on 12 wild animals incidentally caught in pound nets in Denmark (inner Danish waters). Results indicated that although the variability between individuals is wide, the shape of the hearing curve is generally similar to previously published results from behavioral trials. Using 10-kHz frequency intervals between 10 and 160 kHz, best hearing was found between 120 and 130 kHz. Additional testing using one-third octave frequency intervals (from 16 to 160 kHz) allowed for a much faster hearing assessment, but eliminated the fine scale threshold characteristics. For further investigations, the method will be used to better understand the factors influencing sensitivity differences across individuals and to establish population-level parameters describing hearing abilities of harbor porpoises. PMID:27475168

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

    PubMed Central

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

    2010-01-01

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

  10. 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

  11. 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.

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

    PubMed

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

    2016-05-01

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

  13. 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

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

    PubMed

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

    2014-12-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    PubMed

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

    2006-01-01

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

  17. [Changes in early auditory evoked potentials in acoustic neuroma].

    PubMed

    Hoth, S

    1991-09-01

    The auditory brain-stem responses (ABRs) of 38 patients with acoustic neuroma (AN) were recorded pre-operatively and evaluated with regard to pathological deviations from the normal. Several qualitative and quantitative features of the ABRs were compared statistically with the results obtained from a control group for age and sex, and considering patients with various cochlear pathologies (Meniere's disease, sudden deafness, presbycusis). Retrocochlear disorders were ruled out by computed tomography or magnetic resonance imaging. Statistical analysis yielded the following results. The central conduction time (latency difference between Jewett waves J1 and J5) is significantly prolonged in the AN group. A critical value of 4.3 ms separates the retrocochlear from the cochlear lesions, with a sensitivity and specificity of 90%. If conductive hearing loss can be excluded, and if the amount of cochlear hearing loss is taken into account, about the same separation effectively is achieved by evaluation of the sole latency of J5 and its stimulus level dependence. The interaural difference of the central conduction time can be a useful parameter for indicating the presence of acoustic tumours, unless both sides are affected. The same is true of the interaural differences for the J5 latency, but this quantity must be corrected for the effects of peripheral hearing loss. The critical interaural difference values are 0.3 ms for the conduction time (at any stimulus level) and 0.5 ms for the latency of J5 (for stimulus levels above 60 dB nHL). A weaker distinction is provided by the amplitude of J5 and the amplitude ratio of J5 and J1. These quantities are only slightly smaller in cases of AN. Only the combination of small J5 amplitudes with large latency values can be regarded as being characteristic of retrocochlear lesions. This can be highlighted in an amplitude-latency diagram. Further hints as to the site of the lesion can be obtained from a distorted waveform morphology

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

    PubMed

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

    2002-03-01

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

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

    PubMed

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

    2009-08-01

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

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

    PubMed Central

    Katifi, H A; Sedgwick, E M

    1987-01-01

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

  1. 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

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

    PubMed

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

    2016-08-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    1992-04-01

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

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

    PubMed

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

    2014-06-11

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

  8. Effect Of Electromagnetic Waves Emitted From Mobile Phone On Brain Stem Auditory Evoked Potential In Adult Males.

    PubMed

    Singh, K

    2015-01-01

    Mobile phone (MP) is commonly used communication tool. Electromagnetic waves (EMWs) emitted from MP may have potential health hazards. So, it was planned to study the effect of electromagnetic waves (EMWs) emitted from the mobile phone on brainstem auditory evoked potential (BAEP) in male subjects in the age group of 20-40 years. BAEPs were recorded using standard method of 10-20 system of electrode placement and sound click stimuli of specified intensity, duration and frequency.Right ear was exposed to EMW emitted from MP for about 10 min. On comparison of before and after exposure to MP in right ear (found to be dominating ear), there was significant increase in latency of II, III (p < 0.05) and V (p < 0.001) wave, amplitude of I-Ia wave (p < 0.05) and decrease in IPL of III-V wave (P < 0.05) after exposure to MP. But no significant change was found in waves of BAEP in left ear before vs after MP. On comparison of right (having exposure routinely as found to be dominating ear) and left ears (not exposed to MP), before exposure to MP, IPL of IIl-V wave and amplitude of V-Va is more (< 0.001) in right ear compared to more latency of III and IV wave (< 0.001) in left ear. After exposure to MP, the amplitude of V-Va was (p < 0.05) more in right ear compared to left ear. In conclusion, EMWs emitted from MP affects the auditory potential. PMID:27530007

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

    PubMed

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

    2003-04-26

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

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

    PubMed

    Billings, Curtis J; Grush, Leslie D

    2016-08-01

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

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

    PubMed

    Young, Yi-Ho

    2013-02-01

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

  12. 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…

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

    EPA Science Inventory

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

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

    PubMed

    Taylor, P K; Wynn-Williams, G M

    1986-07-01

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

  16. 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…

  17. 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...

  18. 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...

  19. 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...

  20. 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...

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

    ERIC Educational Resources Information Center

    Bates, Tim; And Others

    1995-01-01

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

  2. 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...

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

    PubMed

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

    2016-01-01

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

  4. Auditory evoked potential P300 in adults: reference values

    PubMed Central

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

    2016-01-01

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

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

    PubMed

    Geer, I; Spafford, M M

    1994-01-01

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

  6. 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

  7. The Use of Evoked Potentials in Sleep Research

    PubMed Central

    Colrain, Ian M.; Campbell, Kenneth B.

    2009-01-01

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

  8. ALTERATIONS IN RAT FLASH AND PATTERN REVERSAL EVOKED POTENTIALS AFTER ACUTE OR REPEATED ADMINISTRATION OF CARBON DISULFIDE (CS2)

    EPA Science Inventory

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

  9. Sufentanil and nitrous oxide anaesthesia for the recording of transcranial magnetic motor evoked potentials in dogs.

    PubMed

    Van Ham, L M; Nijs, J; Mattheeuws, D R; Vanderstraeten, G G

    1996-06-29

    Transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle of the forelimbs and from the cranial tibial muscle of the hindlimbs of anaesthetised dogs. The dogs were premedicated with droperidol and fentanyl and a light plane of anaesthesia was induced and maintained with sufentanil and nitrous oxide. The potentials recorded under sufentanil and nitrous oxide anaesthesia were suppressed in comparison with baseline recordings under droperidol and fentanyl sedation: their latencies were significantly increased and their amplitudes significantly decreased (P < 0.05). However, the potentials could be recorded reliably in all the dogs and with very good reproducibility. This narcotic anaesthesia also allowed sensory evoked potentials to be recorded reliably. PMID:8817859

  10. Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

    PubMed

    Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

    2012-01-01

    Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. PMID:21728204