Journal of Neurophysiology, Vol 56, Issue 4 1088-1101, Copyright © 1986 by APS
Cat area 17. III. Response properties and orientation anisotropies of corticotectal cells
T. G. Weyand, J. G. Malpeli, C. Lee and H. D. Schwark
The receptive field properties of antidromically identified corticotectal
(CT) cells in area 17 were explored in the paralyzed, anesthetized cat. To
compare these with another population of infragranular cells, we also
examined the receptive field properties of cells in layer 6. Sixty percent
of our sample of CT cells showed increased response to increased stimulus
length (length summation) and were classified as standard complex cells.
The other 40% showed little or no length summation, were generally end
stopped, and were classified as special complex cells. Standard and special
complex CT cells have complementary orientation anisotropies: the
distribution of orientation preferences of standard complex cells is biased
toward obliquely oriented stimuli, whereas special complex cells are biased
toward horizontally and vertically oriented stimuli. The receptive fields
of the cells in our sample were primarily along the horizontal meridian so
we cannot determine if these anisotropies are defined relative to the
vertical meridian or relative to the meridian passing through the receptive
field. The effects of these anisotropies in preferred orientation are
minimized by the broad orientation tuning of CT cells. There was no simple
relationship between the direction bias of CT cells and the reported
direction bias of tectal cells. In contrast to the heterogeneity of
corticotectal cells, layer 6 cells uniformly showed strong length
summation, tight orientation tuning, and little spontaneous activity.
