Smiley John F, Hackett Troy A, Ulbert Istvan, Karmas George, Lakatos Peter, Javitt Daniel C, Schroeder Charles E
Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.
J Comp Neurol. 2007 Jun 20;502(6):894-923. doi: 10.1002/cne.21325.
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.
尾内侧听觉区（CM）具有解剖学和生理学特征，与其作为第一阶段（或“带状”）听觉联合皮层的作用相一致。它也是多感觉汇聚的部位，具有强烈的体感和听觉反应。在本研究中，我们通过向猕猴注射逆行示踪剂，研究了CM体感和听觉输入的大脑皮层来源。一篇配套论文描述了CM的丘脑连接（哈克特等人，《比较神经学杂志》[本期]）。CM体感输入的可能皮层来源是相邻的岛后回皮层（区域Ri）和颗粒岛叶（Ig）。此外，CM与多感觉整合部位的Tpt和TPO区域有可靠的连接。CM还与其他听觉区域有拓扑连接。正如预期的那样，与相邻尾侧听觉区域的连接比与吻侧区域的连接更强。令人惊讶的是，与核心区域的连接集中在其内侧，这表明核心区域内可能存在功能的内外侧划分。向尾侧外侧听觉区（CL）和Tpt的额外注射显示与Ri、Ig和TPO有类似的连接。与CM注射不同，这些外侧注射有来自顶叶7a区的输入，并且与Tpt的外侧（脑回）部分有优先连接。综上所述，这些发现表明CM可能从外侧沟底部附近区域接收体感输入。与相邻区域相比，CM的不同连接为各个听觉带状区域的功能特化提供了额外证据。
