Intensity difference thresholds in pigeons after lesions of the tectofugal and thalamofugal visual pathways.

Abstract

Obtained visual intensity difference thresholds from 11 White Carneaux pigeons before and after thalamic lesions. Ss with lesions in nucleus rotundus (the thalamic component of the tectofugal pathway) showed moderate postoperative threshold elevations. After extensive retraining the thresholds returned to the preoperative value. Ss with lesions in the nucleus opticus principalis thalami (OPT), the thalamic component of the thalamofugal pathway, had smaller postoperative threshold elevations than the nucleus rotundus cases, but the deficit did not diminish after extensive retraining. Ss with combined lesions of both pathways (OPT + rotundus) had severe postoperative threshold elevations, which declined with retraining to the level of the Ss with OPT lesions, but not to the preoperative level. (36 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)