Perceptual grouping correlates with short synchronization in monkey prestriate cortex.

Synchronization in the visual cortex at 35-80 Hz is assumed to support perceptual grouping. We tested this hypothesis in a figure-ground task in which a trained monkey indicated by a key whether he perceived a figure that was composed of the same blobs as the background distractors. The task was sufficiently difficult such that about 25% of responses were incorrect. We recorded population activity with 7 microelectrodes in prestriate cortex (V2). During a short period before the monkey's perceptual response, locations of figure-activated neurons showed increased synchronization (50-80 Hz) in correct compared to incorrect responses, while other signal measures were unrelated to perception. These are first indications that a short synchronous burst in V2 may support perceptual grouping.