Bordi F, LeDoux J E
Center for Neural Science, New York University, NY 10003.
Exp Brain Res. 1994;98(2):261-74. doi: 10.1007/BF00228414.
Projections from the auditory thalamus to the amygdala have been implicated in the processing of the emotional significance of auditory stimuli. In order to further our understanding of the contribution of thalamoamygdala projections to auditory emotional processing, acoustic response properties of single neurons were examined in the auditory thalamus of chloral hydrate-anesthetized rats. The emphasis was on the medial division of the medial geniculate body (MGm), the suprageniculate nucleus (SG), and the posterior intralaminar nucleus (PIN), thalamic areas that receive inputs from the inferior colliculus and project to the lateral nucleus of the amygdala (AL). For comparison, recordings were also made from the specific thalamocortical relay nucleus, the ventral division of the medial geniculate body (MGv). Responses latencies were not statistically different in MGv, MGm, PIN, and SG, but were longer in the posterior thalamic region (PO). Overall, frequency tuning functions were narrower in MGv than in the other areas but many cells in MGm were as narrowly tuned as cells in MGv. There was some organization of MGv, with low frequencies represented dorsally and high frequencies ventrally. A similar but considerably weaker organization was observed in MGm. While the full range of frequencies tested (1-30 kHz) was represented in MGv, cells in MGm, PIN, and SG tended to respond best to higher frequencies (16-30 kHz). Thresholds were higher in PIN than in MGv (other areas did not differ from MGv). Nevertheless, across the various areas, the breadth of tuning was inversely related to threshold, such that more narrowly tuned cells tended to have lower thresholds. Many of the response properties observed in MGm, PIN, and SG correspond with properties found in AL neurons and thus add support to the notion that auditory responses in AL reflect thalamoamygdala transmission.
听觉丘脑向杏仁核的投射与听觉刺激的情感意义加工有关。为了进一步了解丘脑-杏仁核投射对听觉情感加工的作用，我们在水合氯醛麻醉的大鼠听觉丘脑中检测了单个神经元的听觉反应特性。重点研究了内侧膝状体的内侧部（MGm）、上膝状体核（SG）和丘脑后内侧核（PIN），这些丘脑区域接受来自下丘的输入并投射到杏仁核外侧核（AL）。作为对照，我们也在特定的丘脑皮质中继核——内侧膝状体腹侧部（MGv）进行了记录。MGv、MGm、PIN和SG的反应潜伏期无统计学差异，但丘脑后部区域（PO）的潜伏期更长。总体而言，MGv的频率调谐功能比其他区域更窄，但MGm中的许多细胞与MGv中的细胞调谐一样窄。MGv存在一定的组织排列，低频在背侧代表，高频在腹侧代表。在MGm中观察到类似但明显较弱的组织排列。虽然MGv中测试的频率范围（1-30kHz）都有代表，但MGm、PIN和SG中的细胞往往对较高频率（16-30kHz）反应最佳。PIN的阈值高于MGv（其他区域与MGv无差异）。然而，在各个区域中，调谐宽度与阈值呈负相关，即调谐更窄的细胞往往具有更低的阈值。在MGm、PIN和SG中观察到的许多反应特性与AL神经元中的特性相符，因此支持了AL中的听觉反应反映丘脑-杏仁核传递的观点。
