Thalamocortical projections to layer I of the primary auditory cortex in the cat: a horseradish peroxidase study.

HRP injected into layer I of the primary auditory cortex (AI) in the cat labeled neuronal cell bodies ipsilaterally in the medial, dorsal and ventrolateral divisions of the medial geniculate nucleus (MGN), suprageniculate nucleus, and nucleus of the brachium of the inferior colliculus. MGN neurons labeled after HRP injected into layer I were statistically smaller than those labeled after HRP injected into layer IV.