Cite as:
Przybyszewski A W, Kagan I, Snodderly D M, 2003, "Eye position influences contrast responses in V1 of alert monkey" Perception 32 ECVP Abstract Supplement

Eye position influences contrast responses in V1 of alert monkey

A W Przybyszewski, I Kagan, D M Snodderly

Do our cells in V1 respond differently when we look in different places? In order to answer this question, we studied neuronal responses to moving bars in V1 of an alert monkey viewing the bars from different eye positions. The monkey was trained to fixate on an LED attached to the screen placed in three positions: straight (0°), 10° to the right (10R), or 10° to the left (10L) in the horizontal plane. We recorded contrast responses in 21 cells. Changing eye positions significantly influenced the amplitude of the response in 17 cells. In 7/17 cells in the 0° position, in 5/17 cells in the 10R position, and in the remaining 5/17 cells in the 10L position, responses were larger than in the other two positions. We fitted contrast responses r(c) with the Naka - Rushton equation: r(c) = R_max[cⁿ / (cⁿ + c₅₀ⁿ)], where R_max is the maximum response, c is the contrast, c₅₀ is the contrast at the half of R_max, and n is nonlinearity. We analysed only those responses with a sufficiently good fit (estimated by the RMS). In most cases changing the eye position had small influence on n, but significant influence on R_max and c₅₀. We analysed 18 contrast responses to increment and decrement bars. R_max changed, by more than 20%, in 12 cases, and c₅₀ in 14 cases. In 10 measurements, both R_max and c₅₀ changed as the eye position changed. Our preliminary data also suggest that the eye position could differently influence the size of the increment and decrement zones in the classical receptive field of V1 cells.

[Supported by NIH-EY12243.]

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