Morel A, Garraghty P E, Kaas J H
Department of Psychology, Vanderbilt University, Nashville, Tennessee 37240.
J Comp Neurol. 1993 Sep 15;335(3):437-59. doi: 10.1002/cne.903350312.
Microelectrode recordings were used to investigate the tonotopic organization of auditory cortex of macaque monkeys and guide the placement of injections of wheat germ agglutinin-horse radish peroxidase (WGA-HRP) and fluorescent dyes. Anatomical and physiological results were later related to histological distinctions in the same brains after sections were processed for cytoarchitecture, myeloarchitecture, acetylcholinesterase (AchE), or cytochrome oxidase (CO). The experiments produced several major findings. (1) Neurons throughout a broad expanse of cortex were highly responsive to pure tones, and best frequencies could be determined for neurons in arrays of recording sites. (2) The microelectrode recordings revealed two systematic representations of tone frequencies, the primary area (AI) and a primary-like rostral field (R) as previously described. The representation of high to low frequency tones in A1 was largely caudorostral along the plane of the sulcus. A reversal of the order of representation of frequencies occurred in R. (3) AI and R together were coextensive with a koniocellular, densely myelinated zone that expressed high levels of AchE and CO. These architectonic features were somewhat less pronounced in R than AI, but a clear border between the two areas was not apparent. (4) Cortex bordering AI and R was less responsive to tones, but when best frequencies for neurons could be determined, they matched those for adjoining parts of AI and R. (5) Architectonically distinct regions were apparent within some of the cortex bordering AI and R. (6) The major ipsilateral cortical connections of AI were with R and cortex immediately lateral and medial to AI. (7) Callosal connections of AI were predominantly with matched locations in the opposite AI, but they also included adjoining fields. (8) Neurons in the ventral (MGV), medial (MGM), and dorsal (MGD) nuclei of the medial geniculate complex projected to AI and cortex lateral to AI. (9) Injections in cortex responsive to high frequency tones labeled more dorsal parts of MGV than injections in cortex responsive to low frequency tones.
微电极记录被用于研究猕猴听觉皮层的音频定位组织，并指导注射麦胚凝集素-辣根过氧化物酶（WGA-HRP）和荧光染料。之后，在对切片进行细胞结构、髓鞘结构、乙酰胆碱酯酶（AchE）或细胞色素氧化酶（CO）处理后，将解剖学和生理学结果与同一大脑中的组织学差异相关联。这些实验产生了几个主要发现。（1）整个广泛皮层区域的神经元对纯音高度敏感，并且可以确定记录位点阵列中神经元的最佳频率。（2）微电极记录揭示了音频频率的两种系统表征，即如前所述的初级区域（AI）和初级样吻侧场（R）。A1中高频到低频音调的表征在很大程度上沿着沟平面从尾侧到吻侧。R中频率表征顺序发生了反转。（3）AI和R共同与一个含粒层、髓鞘密集的区域共存，该区域表达高水平的AchE和CO。这些结构特征在R中比在AI中略显不明显，但两个区域之间没有明显的边界。（4）与AI和R相邻的皮层对音调的反应较弱，但当能够确定神经元的最佳频率时，它们与AI和R相邻部分的频率相匹配。（5）在与AI和R相邻的一些皮层内明显存在结构上不同的区域。（6）AI的主要同侧皮层连接是与R以及AI外侧和内侧紧邻的皮层。（7）AI的胼胝体连接主要是与对侧AI的匹配位置，但也包括相邻区域。（8）内侧膝状体复合体的腹侧（MGV）、内侧（MGM）和背侧（MGD）核中的神经元投射到AI和AI外侧的皮层。（9）与对低频音调有反应的皮层注射相比，对高频音调有反应的皮层注射标记的MGV背侧部分更多。
