Visual Evoked Potentials P100 Research Articles

Correlation of visual evoked potentials with dementia in Parkinson's disease

There has been some debate regarding abnormalities in visual evoked potentials (VEP) in Parkinson's disease (PD). To elucidate the mechanism causing abnormal VEP, we investigated the relationship between VEP and mental function in PD patients. Pattern reversal VEP was recorded in PD patients (n = 27) and age-matched control subjects (n = 14). PD patients consisted of two subgroups; PD without dementia (nD-PD; n = 17) and PD with dementia (D-PD; n = 10). Dementia was evaluated according to the criteria for dementia assigned in DSM III-R, and mental faculties were estimated by using the mini-mental state examination (MMSE). In pattern VEP recordings, P100 latency and amplitude were measured for each eye stimulated. No patient or control subject had impairment of corrected visual acuity or ophthalmological disease. There was no significant difference in age among the three groups (D-PD, nD-PD and control subjects). D-PD patients showed significantly prolonged P100 latency compared to nD-PD patients and control subjects (p less than 0.05). With respect to P100 amplitude, no significant difference was shown among the three groups. In PD patients, there was a rough correlation between P100 latency and MMSE score. No correlation was found between P100 amplitude and MMSE score. In control subjects, P100 latency did not correlate with advancing age. In PD patients, nD-PD patients showed a significant correlation between P100 latency and age, whereas D-PD patients presented no correlation. Abnormal VEP in PD has been mostly ascribed to dopaminergic deficiency in the retina.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of pattern size on amplitude, latency and wave form of retinal and cortical potentials elicited by checkerboard pattern reversal and stimulus onset-offset

Transient pattern electroretinograms (PERGs) and visual evoked potentials (VEPs) were recorded with checkerboard pattern reversal and equiluminance stimulus onset-offset, elicited by a high quality moving mirror stimulator. Different sized checkerboard patterns (0.35–4.2 c/deg) were used as stimulus patterns. The wave forms of the equiluminance stimulus onset responses were similar to ERGs evoked with luminance decrease and the stimulus offset PERGs were like ERGs elicited by luminance increase. The PERG c wave and the VEP showed spatial frequency tuning with pattern reversal and stimulus offset. Spatial frequency tuning was not detectable with PERG a and b waves. Pattern reversal and stimulus onset evoked PERGs had no major spectral components above 40 Hz; stimulus offset evoked PERGs contained components up to 55.3 Hz. Retino-cortical time — measured as a latency difference of the PERG b wave to VEP P100 — was identical with pattern reversal and stimulus onset and about 12 msec longer with stimulus offset. Our results suggest that the 3 stimulation modes, reversal, onset and offset induce different types of processing at the retinal and cortical levels. PERG a and b waves to our high luminance/contrast stimuli contain no pattern specific information and the c waves are the sum of luminance and pattern specific responses.

Electroencephalography, evoked potentials and MRI brain scans in saturation divers. An epidemiological study

One hundred and fifty-six air and saturation divers, mean age 33.6 (range 21–49) years, were examined. The control group consisted of 100 offshore workers and policemen with the health requirements to have a diving certificate, mean age 34.0 (range 22–48) years. The examination protocol included electroencephalography (EEG), visual evoked potentials (VEPs), brain-stem auditory evoked potentials (BAEPs) and magnetic resonance imaging (MRI) of the brain and brain-stem. Abnormal EEGs, with focal slow waves mostly in the temporal regions and sharp potentials, were found in 18% of the divers and in 5% of the controls ( P = 0.003). Abnormal EEGs correlated significantly with the exposure to saturation diving ( P = 0.0006) and the prevalence of decomposition sickness ( P = 0.0102). Alcohol consumption was negatively correlated with abnormal EEGs ( P = 0.0006). Mean I–III BAEP latency was increased ( P = 0.047) in the diver group. P100 VEP latency decreased with age (21–49 years). High signal intensity changes obtained by MRI were found in 33% of the divers and in 43% of the controls ( P = 0.14). It is concluded that the nervous system of saturation divers is influenced by their occupation and that EEG is a useful method in the health examination of divers.

Multimodality Exploration of Event‐Related Potentials in Chronic Alcoholics

Short- and long-latency auditory evoked potentials (SAEPs and LAEPs), visual-evoked potentials (VEPs), and contingent negative variation (CNV) were studied in 32 chronic alcoholics and their age-, sex-, and education-matched control subjects. The alcoholics exhibited a delayed SAEP peak V and an increase in the III-V and I-V intervals, increased VEP P100 latency, increased LAEP N2 and P3 latencies and increased LAEP N1-P2 amplitude. The analysis of the anomalies at a clinical level indicates a differential sensitivity of the event-related potentials. The parameters most sensitive to chronic alcohol consumption were (in descending order) P3 latency, peak V latency, the I-V and III-V intervals, and P100 latency.

Hemispheric differences for visual evoked potentials from checkerboard stimuli

Visual evoked potentials (VEPs) were elicited in right-handed male subjects with an alternating checkerboard pattern stimulus presented to either the left or right visual half-field. The sizes of the individual checks in different conditions were 0.25, 0.5, 2.0, or 4.0 cycles/degree of visual angle. The amplitude of the P100 VEP decreased while peak latency increased as check size decreased across both visual field conditions. Left hemisphere responses demonstrated significantly larger P100 amplitudes compared to the right hemisphere responses, although the interaction between hemisphere and stimulus size was not significant. No hemispheric effects of P100 latency were observed. The results suggest that the left hemisphere is engaged more than the right hemisphere for the sensory analysis of visual stimuli composed of straight edges over a wide range of spatial frequencies.

Changes in visual evoked potentials induced by tricyclic antidepressants in patients with endogenous depression

Changes in visual evoked potentials (VEP) induced by tricyclic antidepressants in patients with endogenous depression were studied.VEP was recorded 3-5 times consecutively before and during the treatment. Drug-induced changes in the amplitude-ratios of P100 of VEP after loading mental tasks as well as the changes in the amplitude and latency of the baseline VEP before the tasks were studied during the treatment with amitriptyline (AMP) or imipramine (IMP).The results were as follows :1) The amplitude-ratios after loading the tasks increased at least once in the course of the treatment with AMP or IMP. The increase reached the level of statistical significance only when the doses of more than 75 mg per day were given.2) With the doses of less than 75 mg per day the amplitude-ratios after the tasks scarcely showed any changes in patients treated with AMP, but showed a slight increase in patients with IMP.3) In cases of continuous high dose administration of the drugs re-decrease of the amplituderatios sometimes occurred. The re-decrease was more often seen in patients treated with AMP than in those with IMP.4) While amplitude of P100 of the baseline VEP before the tasks tended to decrease according to the dose increase in patients treated with AMP, no consistent changes were seen in patients with IMP regardless of the dose. No relationship was observed between P100 latency and the dose in patients treated with AMP, nor in those treated with IMP.From these results, it is inferred that both AMP and IMP simultaneously affected stimulatory and inhibitory processes in depressive patients, and that AMP showed stronger inhibitory effects and IMP stronger stimulatory ones.