Garcia Michellee M, Kline Amber M, Onodera Koun, Tsukano Hiroaki, Dandu Pranathi R, Acosta Hailey C, Kasten Michael R, Manis Paul B, Kato Hiroyuki K
Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Nat Commun. 2025 Jul 1;16(1):5911. doi: 10.1038/s41467-025-61020-9.
Auditory processing in the cerebral cortex is considered to begin with thalamocortical inputs to layer 4 (L4) of the primary auditory cortex (A1). In this canonical model, A1 L4 inputs initiate a hierarchical cascade that propagates to higher-order cortices for slower integration of complex sounds. Here, we identify parallel ascending pathways in mice that bypass A1 and directly reach the secondary auditory cortex (A2), alongside the canonical hierarchical route. We found that layer 6 (L6) of both A1 and A2 receive short-latency (<10 ms) sound inputs via higher-order thalamic nuclei. Additionally, A2 L4 is innervated by a caudal subdivision of the traditionally defined primary thalamus, which we now re-classify as non-primary. Notably, both identified thalamic regions receive projections from distinct subdivisions of the higher-order inferior colliculus, which in turn receive direct projections from cochlear nucleus neurons. Thus, higher-order auditory cortex integrates both slower, pre-processed information and rapid, direct sensory inputs, enabling parallel processing of fast sensory information across cortical areas.
大脑皮层中的听觉处理被认为始于丘脑皮质向初级听觉皮层(A1)第4层(L4)的输入。在这个经典模型中,A1 L4输入启动一个层级级联,该级联传播到高阶皮层以对复杂声音进行较慢的整合。在这里,我们在小鼠中识别出平行的上行通路,这些通路绕过A1并直接到达次级听觉皮层(A2),同时存在经典的层级路线。我们发现,A1和A2的第6层(L6)通过高阶丘脑核接收短潜伏期(<10毫秒)的声音输入。此外,A2 L4由传统定义的初级丘脑的一个尾侧细分支配,我们现在将其重新分类为非初级。值得注意的是,两个已识别的丘脑区域都接收来自高阶下丘不同细分的投射,而高阶下丘又接收来自耳蜗核神经元的直接投射。因此,高阶听觉皮层整合了较慢的、经过预处理的信息和快速的、直接的感觉输入,从而实现跨皮层区域对快速感觉信息的并行处理。
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