Interaction of optic tract and visual wulst impulses on single units of the pigeon's optic tectum.

The influences of visual wulst and optic tract (OTr) stimulation on units recorded from the pigeon's optic tectum (OT) were studied. 127 tectal units were excited with short latency by a single OTr volley. Excitation was followed by a long-lasting inhibition. On 54 of the OTr-excited units, single-shock visual wulst stimulation exerted a long-lasting inhibitory effect. On 34 units, the effect was purely excitatory and, on 28 units, excitation was followed by prolonged inhibition. No effect was exerted by wulst stimulation on 24 units. These results are discussed in terms of convergence of wulst and retinal input on OT neurons, and the role of the integration of visual information from both peripheral and central origins is suggested for the OT neurons.