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Modulation of V1 Spike Response by Temporal Interval of Spatiotemporal Stimulus Sequence

Figure 6

Periodic SOA-dependency of surround modulation.

(A) Modulation of spike response in percentage as a function of SOA for three S1 locations of Fig. 5; green: a, blue: b, red: c. (B) Periodic component. The best fit linear trend was removed from the spline fit of modulation percentage in A for each S1 position to remove the monotonic component (detrend.m provided by the MATLAB). (C) The auto-correlogram (black) of the detrended modulation of S1a (green curve of B) was fit with a cosine-Gaussian function, (gray). (D) Hstogram of periodicity. Each case is the first non-zero peak of a cosine-Gaussian function, taken from 53 out of 276 stimulus conditions, for which the cosine-Gaussian fit explained more than 90% variance of auto-correlation curve. For three examples of B, R-squares are 0.99 (S1a), 0.94 (S1b), 0.99 (S1c). The mean periodicity of 53 stimulus conditions is 36.62 ms. (E) Cross-correlation between detrended green and blue curves of B. The time lag at the maximum cross-correlation is 20 ms. This lag reflects the distance between S1a (green) and S1b (blue). Given that cortical distance between S1a and S1b was 3.07 mm, the propagation speed in this example is estimated to be 0.15 m/s. (F) Histogram of propagation speed. Shown is propagation speed for each of 30 cases in which at least one S1 position passed the periodicity criteria of C. The mean distribution is 0.14 m/s without 3 outliers. The median is 0.11 m/s.

Figure 6