title: Effect of color of flash stimulus on variability of flash visual evoked potential latencies.
abstract: Visual Evoked Potentials (VEPs) are evoked potentials generated in response to visual stimuli. The flash VEP (FVEP) is used less frequently than pattern-reversal VEP (PR-VEP) because; it shows great variations in both latency and amplitude in normal subjects. The advantage of FVEP is its feasibility in non-cooperative subjects, which circumvents the major limitation of PR-VEP. The present study was undertaken to assess the effect of change of color of flashlight on variability of FVEP latencies. Healthy subjects in the age group of 18-30 years underwent the standard stimulus using white light, followed by altered stimuli done with red and blue light. 2 trials were given for each eye, for each type of stimulus. The same set of studies was repeated at the same clock time the following day. The inter-individual and intra-individual variability in the peak latency of P2 and N2 waveforms was assessed using coefficient of variation (COV). Both inter-individual and intra-individual variability was less when monochromatic light was used. Between red and blue FVEP, inter-individual variability was less in blue FVEP and the results of intra-individual variability was inconclusive. Monochromatic stimulation preferably with blue light reduced both inter-individual and intra-individual variability seen in latency of P2 and N2 waveforms in FVEP and hence recommended in preference to standard white stimulus for FVEP recording.
authors.affiliation: Department of Physiology, Jawaharlal institute of Postgraduate medical education and research (JIPMER) Puducherry--605 006, India.
authors.forename: Senthil Kumar
authors.initials: SK
authors.lastname: Subramanian
authors.forename: Giriwar Singh
authors.initials: GS
authors.lastname: Gaur
authors.forename: Sunil K
authors.initials: SK
authors.lastname: Narayan
mesh_terms: D000293:Adolescent; D000328:Adult; D003116:Color; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011930:Reaction Time / Q000502:physiology*