Experimental setup for surround suppression without attention.
- Author
- Frederik Beuth
Data: Cavanaugh2002a, Fig. 8A
Significant results (p. 2538, left column):
- Surround suppression is significant and at mean 38% (Fig. 3)
- Neuron has at lower contrasts a larger receptive field (GSF, grating summation field). GSF diameters were for lowest contrast 2.5 times those measured for high contrast.
- It is explained by Fig. 7 and by "At high contrasts, the surround is relatively strong and suppresses weak responses from the flanks of the center mechanism. At low contrasts the surround is relatively weak, and this suppression is relaxed, allowing more of the center to be seen."
- Fig. 8 shows that the model with variable center gain and surround gain fits the data at best.
- Here, we follow the same idea, the surround is weaker for lower contrasts because:
- The suppression depends on the firing rate and thus being weaker for lower contrasts.
- The data is fitted well with using p^SUR > 1, favoring higher firing rates and thus higher contrasts
- Similarly, we model the stimulus along the spatial dimension via a Gaussian.
Setup:
- Stimuli have a size of 0-7° at 5° eccentricity (plus 9% at 5-10°). V1 RF size is 0.6° at 5° ecc. (Smith et al., 2001).
Calibration of the fit:
- 1) Calibrate contrast response function (CRF)
- 2) Calibrate surround suppression for far locations