Synchronization of visual responses in the superior colliculus of awake cats

Multi-unit responses to moving stimuli were recorded simultaneously from se veral sites in the superior colliculus of awake cats. Correlation analysis revealed that response synchronization was a prominent feature of visually evoked neural activity in both superficial and deep collicular layers. Resp onses at about half of the recordings separated by less than or equal to1 m m showed significant correlations. The synchronized responses oscillated in the gamma frequency range (30-70 Hz) which contrasts to conditions in anae sthetized cats where oscillations predominantly occurred in the alpha and b eta frequency range (10-20 Hz). Response synchronization was most pronounce d with coherent motion stimuli and broke down with incoherent stimuli. Thes e results agree with previous findings on corticotectal synchronization and support the hypothesis that synchronization in the millisecond range serve s to group collicular neurons into functionally coherent assemblies. NeuroR eport 12:43-47 (C) 2001 Lippincott Williams & Wilkins.