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S. Kamiya, T. Sato; Motion- and luminance- defined patterns elicit qualitatively same but quantitatively different VEPs. Journal of Vision 2001;1(3):245. doi: 10.1167/1.3.245.
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© ARVO (1962-2015); The Authors (2016-present)
Luminance checkerboard patterns have been extensively used to study human VEPs for spatiotemporal stimuli. MacKay & Jeffreys (1973) identified that three earlier components for these VEPs and argued that component2 (C2) is related to pattern discontinuity. In this study, we examined VEPs to motion defined checkerboard pattern to elucidate the nature of VEPs elicited by luminance and motion-defined checkerboards. A 6.4 × 6.4 deg random-dot field which was divided 256 × 256 pixels (pixel size = 1.5 min) was presented on a CRT screen. The field was divided into 8 × 8 checks. A half of these checks (corresponding to black checks for regular checkerboard) had coherent motion and the rest had incoherent motion to create motion-defined checkerboard. The velocity of coherent motion was 3 min/sec and the dots in incoherent checks were replaced to an uncorrelated pattern every frame. The frame rate was 120Hz. This pattern was displayed for 500 ms and then replaced by a whole-field incoherent pattern for 500 ms. Then, in the new cycle, anti-phase checkerboard with coherent motion in opposite direction was presented. Two males with normal vision served as subjects. Viewing distance was 114cm. VEP's were recorded with a bipolar derivation technique from Oz and O2 with left earlobe as a reference electrode. All recorded VEPs had three components similar to those for luminance stimuli. However the latency for C2 component with motion defined stimuli was about 200 ms, which is twice as long as that for luminance stimuli. In addition, for motion defined stimuli, there was an intriguing positive peak at 300 ms latency. These results indicate a similarity between VEPs elicited by motion-defined and luminance patterns for earlier components, but suggest differences especially for later components.
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