Anatomic organization of the auditory cortex.

The auditory cortex is a network of areas in the part of the brain that receives inputs from the subcortical auditory pathways in the brainstem and thalamus. Through an elaborate network of intrinsic and extrinsic connections, the auditory cortex is thought to bring about the conscious perception of sound and provide a basis for the comprehension and production of meaningful utterances. In this chapter, the organization of auditory cortex is described with an emphasis on its anatomic features and the flow of information within the network. These features are then used to introduce key neurophysiologic concepts that are being intensively studied in humans and animal models. The discussion is presented in the context of our working model of the primate auditory cortex and extensions to humans. The material is presented in the context of six underlying principles, which reflect distinct, but related, aspects of anatomic and physiologic organization: (1) the division of auditory cortex into regions; (2) the subdivision of regions into areas; (3) tonotopic organization of areas; (4) thalamocortical connections; (5) serial and parallel organization of connections; and (6) topographic relationships between auditory and auditory-related areas. Although the functional roles of the various components of this network remain poorly defined, a more complete understanding is emerging from ongoing studies that link auditory behavior to its anatomic and physiologic substrates.