21 area's neurons of the visual cortex revealed obvious low-pass frequency characteristics ranging from 0.05 to 3.5 c/deg in cats. Responses of the neurons to different frequencies ranged from 0.05 to 0.89 c/deg in the left hemisphere and from 0.11 to 3.5 c/deg in the right one. The data obtained suggest that the RF's neurons of the area 21 make low-pass spatial-frequency description of visual images, the left hemisphere making a lower spatial-frequency description of the image than the right one.