AG Leventhal, KG Thompson, D Liu, Y
Zhou and SJ Ault
Department of
Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City
84132.
The receptive field properties of cells in layers 2,
3, and 4 of area 17 (V1) of the monkey were studied quantitatively
using colored and broad-band gratings, bars, and spots. Many cells
in all regions studied responded selectively to stimulus
orientation, direction, and color. Nearly all cells (95%) in layers
2 and 3 exhibited statistically significant orientation preferences
(biases), most exhibited at least some color sensitivity, and many
were direction sensitive. The degree of selectivity of cells in layers 2
and 3 varied continuously among cells; we did not find discrete regions containing
cells sensitive to orientation and direction but not color, and vice
versa. There was no relationship between the degree of orientation sensitivity
of the cells studied and their degree of color sensitivity. There
was also no obvious relationship between the receptive field properties
studied and the cells' location relative to cytochrome oxidase-rich
regions. Our findings are difficult to reconcile with the hypothesis
that there is a strict segregation of cells sensitive to orientation,
direction, and color in layers 2 and 3. In fact, the present results
suggest the opposite since most cells in these layers are selective for
a number of stimulus attributes.