Behavioral evidence for cortical involvement in manual temperature discrimination in the monkey

Abstract

Four monkeys (Macaca mulatta) have been trained to make a temperature discrimination of about 1 C by touching the discriminanda with one hand. Extensive removal of postcentral cortex raised the differential threshold slightly in one monkey, but another was unaffected. After additional removal of precentral cortex in two monkeys, there was no recovery from paresis in the contralateral hand. Two monkeys trained to a 1 C differential with one hand showed good transfer to the other hand for temperature differences greater than 6 C, but random performance with a 1 C temperature difference. In one monkey trained to a 1 C differential with one hand the corpus callosum was sectioned, and the other hand then performed randomly on a 20 C temperature difference. In another monkey trained to 1 C with one hand the precentral and postcentral gyri were removed in the hemisphere opposite to the trained hand. The untrained hand then performed randomly with a 20 C temperature difference. There is thus some evidence for cortical involvement in manual temperature discrimination, but this function is not confined to the post-central cortex. The effect of posterior thalamic lesions has been tested in one monkey.