Physiology of Neuronal Networks, Department of Biology, RPTU University of Kaiserslautern-Landau, Kaiserslautern, Germany.
Front Neural Circuits. 2023 Jul 13;17:1210057. doi: 10.3389/fncir.2023.1210057. eCollection 2023.
The auditory cortex (AC) modulates the activity of upstream pathways in the auditory brainstem via descending (corticofugal) projections. This feedback system plays an important role in the plasticity of the auditory system by shaping response properties of neurons in many subcortical nuclei. The majority of layer (L) 5 corticofugal neurons project to the inferior colliculus (IC). This corticocollicular (CC) pathway is involved in processing of complex sounds, auditory-related learning, and defense behavior. Partly due to their location in deep cortical layers, CC neuron population activity patterns within neuronal AC ensembles remain poorly understood. We employed two-photon imaging to record the activity of hundreds of L5 neurons in anesthetized as well as awake animals. CC neurons are broader tuned than other L5 pyramidal neurons and display weaker topographic order in core AC subfields. Network activity analyses revealed stronger clusters of CC neurons compared to non-CC neurons, which respond more reliable and integrate information over larger distances. However, results obtained from secondary auditory cortex (A2) differed considerably. Here CC neurons displayed similar or higher topography, depending on the subset of neurons analyzed. Furthermore, specifically in A2, CC activity clusters formed in response to complex sounds were spatially more restricted compared to other L5 neurons. Our findings indicate distinct network mechanism of CC neurons in analyzing sound properties with pronounced subfield differences, demonstrating that the topography of sound-evoked responses within AC is neuron-type dependent.
听觉皮层（AC）通过下行（皮质传出）投射调节听觉脑干中上游通路的活动。这个反馈系统通过塑造许多皮质下核神经元的反应特性，在听觉系统的可塑性中起着重要作用。大多数第 5 层（L5）皮质传出神经元投射到下丘（IC）。这种皮质-丘系（CC）通路参与复杂声音的处理、听觉相关的学习和防御行为。部分由于它们位于皮质深层，CC 神经元群体在神经元 AC 集合中的活动模式仍然知之甚少。我们使用双光子成像技术记录了麻醉和清醒动物数百个 L5 神经元的活动。CC 神经元的调谐比其他 L5 锥体神经元更宽，在核心 AC 亚区中显示出较弱的地形顺序。网络活动分析显示，与非 CC 神经元相比，CC 神经元具有更强的聚类，它们的反应更可靠，并且可以在更大的距离上整合信息。然而，从次级听觉皮层（A2）获得的结果则大不相同。在这里，CC 神经元显示出相似或更高的地形，具体取决于分析的神经元子集。此外，特别是在 A2 中，与其他 L5 神经元相比，响应复杂声音的 CC 活动聚类在空间上受到限制。我们的发现表明 CC 神经元在分析声音特性时具有独特的网络机制，并且具有明显的亚区差异，证明了 AC 内声音诱发反应的地形是神经元类型依赖性的。
