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Multisensory convergence in auditory cortex, I. Cortical connections of the caudal superior temporal plane in macaque monkeys
Author(s) -
Smiley John F.,
Hackett Troy A.,
Ulbert Istvan,
Karmas George,
Lakatos Peter,
Javitt Daniel C.,
Schroeder Charles E.
Publication year - 2007
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21325
Subject(s) - macaque , biology , neuroscience , auditory cortex , cortex (anatomy) , temporal cortex , anatomy
Abstract The caudal medial auditory area (CM) has anatomical and physiological features consistent with its role as a first‐stage (or “belt”) auditory association cortex. It is also a site of multisensory convergence, with robust somatosensory and auditory responses. In this study, we investigated the cerebral cortical sources of somatosensory and auditory inputs to CM by injecting retrograde tracers in macaque monkeys. A companion paper describes the thalamic connections of CM (Hackett et al., J. Comp. Neurol. [this issue]). The likely cortical sources of somatosensory input to CM were the adjacent retroinsular cortex (area Ri) and granular insula (Ig). In addition, CM had reliable connections with areas Tpt and TPO, which are sites of multisensory integration. CM also had topographic connections with other auditory areas. As expected, connections with adjacent caudal auditory areas were stronger than connections with rostral areas. Surprisingly, the connections with the core were concentrated along its medial side, suggesting that there may be a medial‐lateral division of function within the core. Additional injections into caudal lateral auditory area (CL) and Tpt showed similar connections with Ri, Ig, and TPO. In contrast to CM injections, these lateral injections had inputs from parietal area 7a and had a preferential connection with the lateral (gyral) part of Tpt. Taken together, the findings indicate that CM may receive somatosensory input from nearby areas along the fundus of the lateral sulcus. The differential connections of CM compared with adjacent areas provide additional evidence for the functional specialization of the individual auditory belt areas. J. Comp. Neurol. 502:894–923, 2007. © 2007 Wiley‐Liss, Inc.