The important visual stimulus parameters Fur a given cell are defined by th
e classical receptive field (CRF). However, cells are also influenced by vi
sual stimuli presented in areas surrounding the CRF. The experiments descri
bed here were conducted to determine the incidence and nature of CRF surrou
nd influences in the primary visual cortex. From extracellular recordings i
n the cat's striate cortex, we find that for over half of the cells investi
gated (56%, 153/271), the effect of stimulation in the surround of the CRF
is to suppress the neuron's activity by at least 10% compared to the respon
se to a grating presented within the CRF alone. For the remainder of the ce
lls, the interactions were minimal and a few were of a facilitatory nature.
In this paper, we focus on the suppressive interactions. Simple and comple
x cell types exhibit equal incidences of surround suppression. Suppression
is observed for cells in all layers, and its degree is strongly correlated
between the two eyes for binocular neurons. These results show that surroun
d suppression is a prevalent form of inhibition and may play an important t
ote in visual processing.