In this study,we investigated orientation selectivity in cat primary visual cortex(V1) and its relationship with various parameters.We found a strong correlation between circular variance(CV) and orthogonal-topreferred response ratio(O/P ratio),and a moderate correlation between tuning width and O/P ratio.Moreover,the suppression far from the peak that accounted for the lower CV in cat V1 cells also contributed to the narrowing of the tuning width of cells.We also studied the dependence of orientation selectivity on the modulation ratio for each cell,which is consistent with robust entrainment of the neuronal response to the phase of the drifting grating stimulus.In conclusion,the CV(global measure) and tuning width(local measure) are significantly correlated with the modulation ratio.
A sensory stimulus can only be properly interpreted in light of the stimuli that surround it in space and time. The tilt illusion(TI) and tilt after-effect(TAE) provide good evidence that the perception of a target depends strongly on both its spatial and temporal context. In previous studies, the TI and TAE have typically been investigated separately, so little is known about their co-effects on visual perception and information processing mechanisms. Here, we considered the influence of the spatial context and the temporal effect together and asked how centersurround context affects the TAE in foveal and parafoveal vision. Our results showed that different center-surround spatial patterns signifi cantly affected the TAE for both foveal and para-foveal vision. In the fovea, the TAE was mainly produced by central adaptive gratings. Cross-oriented surroundings significantly inhibited the TAE, and iso-oriented surroundings slightly facilitated it; surround inhibition was much stronger than surround facilitation. In the para-fovea, the TAE was mainly decided by the surrounding patches. Likewise, a cross-oriented central patch inhibited the TAE, and an iso-oriented one facilitated it, but there was no significant difference between inhibition and facilitation. Our findings demonstrated, at the perceptual level, that our visual system adopts different mechanisms to process consistent or inconsistent central-surround orientation information and that the unequal magnitude of surround inhibition and facilitation is vitally important for the visual system to improve the detectability or discriminability of novel or incongruent stimuli.
Cheng ChenXianghui ChenMin GaoQiong YangHongmei Yan
