RT Journal Article
SR Electronic
T1 Early and Late Mechanisms of Surround Suppression in Striate Cortex of Macaque
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 11666
OP 11675
DO 10.1523/JNEUROSCI.3414-05.2005
VO 25
IS 50
A1 Ben S. Webb
A1 Neel T. Dhruv
A1 Samuel G. Solomon
A1 Chris Tailby
A1 Peter Lennie
YR 2005
UL http://www.jneurosci.org/content/25/50/11666.abstract
AB The response of a neuron in striate cortex to an optimally configured visual stimulus is generally reduced when the stimulus is enlarged to encroach on a suppressive region that surrounds its classical receptive field (CRF). To characterize the mechanism that gives rise to this suppression, we measured its spatiotemporal tuning, its susceptibility to contrast adaptation, and its capacity for interocular transfer. Responses to an optimally configured grating confined to the CRF were strongly suppressed by annular surrounding gratings drifting at a wide range of temporal and spatial frequencies (including spatially uniform fields) that extended from well below to well above the range that drives most cortical neurons. Suppression from gratings capable of driving cortical CRFs was profoundly reduced by contrast adaptation and showed substantial interocular transfer. Suppression from stimuli that lay outside the spatiotemporal passband of most cortical CRFs was relatively stronger when the stimulus on the CRF was of low contrast, was generally insusceptible to contrast adaptation, and showed little interocular transfer. Our findings point to the existence of two mechanisms of surround suppression: one that is prominent when high-contrast stimuli drive the CRF, is orientation selective, has relatively sharp spatiotemporal tuning, is binocularly driven, and can be substantially desensitized by adaptation; the other is relatively more prominent when low-contrast stimuli drive the CRF, has very broad spatiotemporal tuning, is monocularly driven, and is insusceptible to adaptation. Its character suggests an origin in the input layers of primary visual cortex, or earlier.