Lateral suprasylvian visual cortex is activated earlier than or synchronously with primary visual cortex in the cat

To explore functional connectivity between area 17 and posteromedial lateral suprasylvian (PMLS) area of the cat cerebral cortex, we carried out cross-correlation analysis of spike trains of neurons recorded simultaneously from both areas of anesthetized, paralyzed cat. Most of correlated pairs had peaks which indicate that PMLS cells were activated earlier than or simultaneously with their partners in area 17, suggesting that 'backward' as well as synchronous activation operates between these cortical areas.