SUMMARY
Human psychophysical studies demonstrate that visual detection thresholds are sometimes close to the limits imposed by the physics of the stimulus. Another potential limit is the variable spiking of cortical neurons, which theoretically reduces information about the stimulus. The correlation structure of noise in the cortical population is critical in setting this limit. We investigated these correlations by recording simultaneously from visual cortical areas V1 and V4 in macaque monkeys during performance of a stereo depth detection task. We found evidence of rapid, information-limiting, noise correlations within each area, at a temporal scale of tens of ms. However, the correlation structure between the two areas had a different pattern at temporal scales of 100+ms that attenuated within-area correlations, potentially supporting recovery of information. We suggest that processing in multiple, distinct cortical areas may aid the estimation and attenuation of information-limiting noise correlations.