Synchrony and the binding problem in macaque visual cortex

We tested the binding-by-synchrony hypothesis which proposes that object representations are formed by spike activity between neurons that code features of the same object. We studied responses of 32 pairs of recorded with microelectrodes 3 mm apart in the visual cortex of macaques performing a fixation task. Upon mapping receptive fields of the neurons, a quadrilateral was generated so that two of its sides were centered in the receptive fields the optimal orientations. This one-figure condition was compared with a two-figure condition in which the neurons stimulated by two separate figures, keeping the local edges in the receptive fields identical. For each neuron, we determined its border ownership selectivity ( H. Zhou, H. S. Friedman, & R. von der Heydt, 2000). We examined synchronization and correlation at nonzero time lag. After correcting for effects of the. ring rate, we found that did not depend on the binding condition. However,finding synchrony in a pair of neurons was correlated with. border-ownership selectivity in both members of the pair. This suggests that the synchrony reflected the connectivity in network that generates border ownership assignment. Thus, we have not found evidence to support the binding-byhypothesis.