Auditory cortical projections to the superior colliculus in the cat

The auditory cortical projections to the superior colliculus were studied in the cat with silver impregnation methods and it is suggested that the pathway may be related to complex auditory-visual behavioural relationships.

Abstract

The auditory cortical projections to the superior colliculus were studied in the cat with silver impregnation methods. The auditory area AII and the suprasylvian fringe auditory cortex (SF) project bilaterally to the superficial layers of the superior colliculus. The projection is heavier ipsilaterally. The ectosylvian posterior auditory region (EP) projects to the deep layers of the ipsilateral superior colliculus. No evidence was found of fibres to the superior colliculus arising from the auditory cortex AI or from the anterior and posterior sylvian gyri (insulo-temporal auditory cortex). The dorso-caudal turn of the ectosylvian gyrus has apparently only scanty projections to the deep layers of the ipsilateral superior colliculus but projects heavily to pretectal areas. These findings are compared with earlier evidence of auditory cortical projections to the superior colliculus. The possible functions of this pathway are briefly discussed, and it is suggested that the pathway may be related to complex auditory-visual behavioural relationships.