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Jonathan W. Page, Jennifer R. Highsmith, Michael A. Crognale; Contrast response and components of the achromatic onset visual evoked potential. Journal of Vision 2004;4(8):545. doi: 10.1167/4.8.545.
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© ARVO (1962-2015); The Authors (2016-present)
Direct comparisons of visual evoked potential (VEP) responses for the chromatic and achromatic pathways are difficult since stimulus conditions that best modulate the individual pathways are different. When stimuli conditions are chosen that best modulate the chromatic pathways, characteristic waveform response components for achromatic stimuli are difficult to identify because the resultant waveforms have low signal-to-noise ratios. We measured VEP responses to low spatial frequency (1.0 c/deg) sinusoidal gratings presented in an onset/offset timing sequence (100ms on, 400ms off) that selectively modulated the L−M, S−(L+M) and achromatic pathways at various contrast levels. Results show latencies and amplitudes of C1, C2, and C3 to change similarly across supra threshold contrast levels up to saturation. At low contrasts, C3 was found to be the most consistently distinguishable component in the achromatic waveform. The results suggest that for some individuals, C3 may be the most reliable measure for onset achromatic responses of low spatial frequency and low contrast. Contrast response functions for latency and amplitude are also presented for chromatic stimuli.
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