Pretectum and superior colliculus in object vs pattern discrimination in the monkey

Abstract

The present study was designed to investigate the role of the collicular-pretectal area in the acquisition of initial learning of pattern vs object discriminations. Naivemonkeys with massive bilateral lesions of the pretectum and superior colliculi were trained in object and pattern discrimination tasks with subsequent generalization. Results showed that lesioned monkeys (1) performs as well as normals on an object discrimination problem and on its subsequent generalization; (2) show great impairment in acquiring an initial pattern discrimination as well as generalizing this task; (3) demonstrate greater difficulty than normals in shifting from tridimensional objects to patterns. These results lead to the conclusion that massive midbrain lesions affect discrimination of patterns leaving intact the capacity of discriminating objects.