Effects of unilateral thalamic lesion upon interocular transfer of visual discrimination in pigeons. II: Lesion in the untrained hemisphere (sensory deficits).

In a previous study, rotundal lesions in the 'trained' hemisphere caused deficits in interocular transfer of visual discrimination when the lesion was made after acquisition of the monocular learning, but not when the lesion was made before the monocular learning. In the present study, a rotundal lesion was made in the 'untrained' hemisphere before and after monocular training. The lesion caused deficits in transfer regardless of the temporal relation between the lesion and the training. Such deficits are likely to be 'sensory deficits' since visual information from the eye goes to the damaged rotundus when tested with the untrained eye. The relation between the 'sensory' versus 'mnemonic' deficits from damage to nucleus rotundus in the trained hemisphere are discussed.