Lack of cortico-striatal projections from the primary auditory cortex in the squirrel monkey

The projections of the superior temporal gyrus to the caudate nucleus were studied in 10 squirrel monkeys (Saimiri sciureus). It was found that the pr imary auditory cortex lacks direct connections with the caudate nucleus as well as the putamen. Areas RL and T1 of Burton and Jones, bordering the pri mary auditory cortex laterally, show a moderate projection to the body and tail of the caudate nucleus; area T2, bordering areas RL and T1, shows an e xtensive projection into the head, body and tail. A comparison of the tempo ro-caudate projections of the monkey with those of rodents and carnivores s uggests that primary and secondary auditory cortices differ in their connec tions in primates more than in other mammals, pointing to a greater functio nal differentiation of these areas in primates. (C) 1999 Elsevier Science B .V. All rights reserved.