PT  - JOURNAL ARTICLE
AU  - Petrov, Yury
AU  - Carandini, Matteo
AU  - McKee, Suzanne
TI  - Two Distinct Mechanisms of Suppression in Human Vision
AID  - 10.1523/JNEUROSCI.2871-05.2005
DP  - 2005 Sep 21
TA  - The Journal of Neuroscience
PG  - 8704--8707
VI  - 25
IP  - 38
4099  - http://www.jneurosci.org/content/25/38/8704.short
4100  - http://www.jneurosci.org/content/25/38/8704.full
SO  - J. Neurosci.2005 Sep 21; 25
AB  - Cortical visual neurons in the cat and monkey are inhibited by stimuli surrounding their receptive fields (surround suppression) or presented within their receptive fields (cross-orientation or overlay suppression). We show that human contrast sensitivity is similarly affected by two distinct suppression mechanisms. In agreement with the animal studies, human surround suppression is tightly tuned to the orientation and spatial frequency of the test, unlike overlay suppression. Using a double-masking paradigm, we also show that in humans, overlay suppression precedes surround suppression in the processing sequence. Surprisingly, we find that, unlike overlay suppression, surround suppression is only strong in the periphery (>1° eccentricity). This result argues for a new functional distinction between foveal and peripheral operations.