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.
