Han Dawei, Tang Yezhong, Christensen-Dalsgaard Jakob, Liang Wenru, Carr Catherine E
Department of Biology, University of Maryland, College Park, Maryland, USA.
Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
J Comp Neurol. 2025 Oct;533(10):e70100. doi: 10.1002/cne.70100.
In reptiles, two taxa, lepidosaurs and archosaurs, have ears with thin tympanic membranes that permit sensitive hearing of high-frequency sounds in air. The organization of their central auditory systems may reflect this increased sensitivity to sound. To understand auditory processing in lepidosaurs further, we used tract tracing techniques to examine the organization and connections of the lemniscal and midbrain auditory nuclei in the Tokay gecko. The nuclei of the lateral lemniscus (LLD) consist of anterior (LLDa), medial (LLDm), and posterior (LLDp) subdivisions and receive ascending projections from the contralateral cochlear nuclei (nucleus angularis and nucleus laminaris) and the ipsilateral dorsal superior olive (SOd). LLD projects to the ventral division of the ipsilateral torus semicircularis (TS). In the Tokay gecko, the central nucleus of the torus (TSC) is large, with two major subdivisions, ventral and dorsal. Caudally, the TSC is fused at the midline, with the dorsal divisions adjoining their contralateral homolog. More rostrally, the TSC bifurcates to form two wings below the tectal ventricles. The ventral division of the TSC receives ascending input from NA/NL, SOd, and the lateral lemniscal complex, while both the dorsal and ventral divisions send descending projections to the lateral lemniscal complex. The TSC projects to the auditory thalamic nucleus medialis through the tractus opticus lateralis. Physiological recordings from TSCv injection sites revealed a patchy distribution of best frequencies, while recordings in TSCd were characterized by broad frequency tuning. The tract tracing results revealed conserved anatomical patterns of ascending auditory connections in lizards and archosaurs.
在爬行动物中，有鳞目和主龙类这两个类群的耳朵具有薄的鼓膜，能够灵敏地听到空气中的高频声音。它们中枢听觉系统的组织结构可能反映了这种对声音增强的敏感性。为了进一步了解有鳞目的听觉处理过程，我们使用束路追踪技术研究了 Tokay 壁虎中lemniscal 和中脑听觉核团的组织结构及连接情况。外侧丘系核（LLD）由前侧（LLDa）、内侧（LLDm）和后侧（LLDp）亚核组成，接受来自对侧耳蜗核（角状核和层状核）和同侧背侧上橄榄核（SOd）的上行投射。LLD 投射到同侧半规管隆起（TS）的腹侧部分。在 Tokay 壁虎中，半规管隆起的中央核（TSC）很大，有两个主要亚区，腹侧和背侧。在尾部，TSC 在中线处融合，背侧部分与对侧同源部分相邻。更靠前的位置，TSC 分叉形成两个位于顶盖脑室下方的翼。TSC 的腹侧部分接受来自 NA/NL、SOd 和外侧丘系复合体的上行输入，而背侧和腹侧部分都向外侧丘系复合体发出下行投射。TSC 通过外侧视束投射到内侧听觉丘脑核。在 TSCv 注射部位的生理记录显示最佳频率呈斑片状分布，而在 TSCd 的记录则以宽频率调谐为特征。束路追踪结果揭示了蜥蜴和主龙类在听觉上行连接方面保守的解剖模式。
