VISUAL AND NONVISUAL UNITS RECORDED FROM OPTIC TECTUM OF GALLUS-DOMESTICUS

Units recorded from the optic tectum were tested for responses to visual, auditory and somesthetic stimuli. Units recorded from the superficial tectal layers (stratum opticum, stratum griseum et fibrosum superficiale) responded only to visual stimuli. On the basis of the unit''s responsiveness to the directionality of a moving visual stimulus, 3 unit types referred to as pandirectional, unidirectional and multidirectional units were identified. In the deeper layers (stratum griseum centrale, stratum album centrale) unimodal and bimodal units were encountered. These units responded to visual, auditory and/or somesthetic stimuli. The tectal cortex of G. domesticus is apparently subdivided into 2 functional divisions: the superficial layers which correlate visual information and the deep layers which correlate visual and nonvisual information.