Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
J Neurosci. 2020 Aug 12;40(33):6328-6344. doi: 10.1523/JNEUROSCI.0646-20.2020. Epub 2020 Jul 14.
The lateral cortex of the inferior colliculus (LCIC) forms a nexus between diverse multisensory, motor, and neuromodulatory streams. Like other integration hubs, it contains repeated neurochemical motifs with distinct inputs: GABA-rich modules are innervated by somatosensory structures, while auditory inputs to the LCIC target the surrounding extramodular matrix. To investigate potential mechanisms of convergence between these input streams, we used laser photostimulation circuit mapping to interrogate local LCIC circuits in adult mice of both sexes and found that input patterns are highly dependent on cell type (GABAergic/non-GABAergic) and location (module/matrix). At the circuit level, these inputs yield a directional flow of local information, primarily from the matrix to the modules. Further, the two compartments were found to project to distinct targets in the midbrain and thalamus. These data show that, while connectional modularity in the LCIC gives rise to segregated input-output channels, local circuits provide the architecture for integration between these two streams. Modularity is a widespread motif across the brain involving the segregation of structures into discrete subregions based on dichotomies in neurochemical expression or connectivity. The inferior colliculus is one such modular structure, containing auditory-recipient matrix regions and GABA-rich modules that are innervated by somatosensory inputs. While modularity suggests segregation of processing streams, here we show that local circuits in the inferior colliculus connect the module and matrix regions, providing an avenue for integration of information across compartments.
下丘外侧核（LCIC）的外侧皮质形成了各种多感觉、运动和神经调质流之间的连接点。像其他整合中枢一样，它包含具有不同输入的重复神经化学基序：富含 GABA 的模块由躯体感觉结构支配，而 LCIC 的听觉输入则靶向周围的模块外基质。为了研究这些输入流之间潜在的汇聚机制，我们使用激光光刺激电路测绘来检测成年雌雄小鼠 LCIC 中的局部电路，发现输入模式高度依赖于细胞类型（GABA 能/非 GABA 能）和位置（模块/基质）。在电路水平上，这些输入产生了局部信息的定向流动，主要是从基质到模块。此外，还发现这两个隔室投射到中脑和丘脑的不同靶区。这些数据表明，尽管 LCIC 中的连接模块导致了分离的输入-输出通道，但局部电路为这两个流之间的整合提供了架构。模块化是一种广泛存在于大脑中的模式，涉及根据神经化学表达或连接的二分法将结构分离成离散的子区域。下丘就是这样一个模块化结构，包含听觉接收基质区域和 GABA 丰富的模块，这些模块由躯体感觉输入支配。虽然模块化暗示了处理流的分离，但我们在这里表明，LCIC 中的局部电路连接了模块和基质区域，为跨隔室的信息整合提供了途径。
