Spatio-temporal dynamics of feedforward and feedback processing in the visual thalamo-cortico-thalamic loop

视觉丘脑-皮质-丘脑环路中前馈和反馈处理的时空动力学

• 批准号: 278757170
• 负责人: Professorin Dr. Laura Busse
• 金额: --
• 依托单位: Lehrstuhl für Neurobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/278757170?language=en
• 关键词: Spatio; temporal; dynamics; feedforward; feedback

In textbooks, the visual system is often portrayed consisting of processing stages that are arranged in a hierarchy and connected via feedforward projections. Considering the anatomy of the visual system in more detail, however, it becomes clear that feedforward projections are often grossly outnumbered by their feedback counterparts. This general rule also applies to the dorsolateral geniculate nucleus (dLGN) of the thalamus, where ~30% of synaptic inputs to relay cells are made by corticothalamic (CT) pyramidal cells, while only ~10% constitute feedforward inputs from retinal ganglion cells. How this anatomically massive feedback projection to one of the earliest visual processing stages influences representations in dLGN and impacts computations in the thalamocortical loop has so far remained incompletely understood.The proposed research is a follow-up project that continues to be centered around the impact of corticothalamic feedback on information processing in the early visual system. While our research in the previous funding period provided insights into the retinotopic organization of CT feedback circuits in thalamus and the dual nature of CT feedback effects in shaping spatial processing, i.e. facilitation and suppression, our central aim for this follow-up proposal is to elucidate the spatio-temporal dynamics of feedforward and feedback processing in thalamo-cortico-thalamic interactions. In particular, we will (1) isolate the temporal impact of CT feedback in dLGN and visTRN, we will (2) investigate the role of CT feedback in shaping spatio-temporal selectivity by using pathway-specific, optogenetic suppression of CT feedback terminals and simultaneous recordings from thalamus and cortex, and we will (3) probe the role of CT feedback in thalamocortical rhythms and communication.Together, this research promises to contribute to answering the fundamental question of how the direct excitatory and indirect inhibitory CT feedback dynamically interact to modulate thalamo-cortical visual processing.

在教科书中，视觉系统通常被描述为由按层次结构排列并通过前馈投影连接的处理阶段组成。然而，更详细地考虑视觉系统的解剖结构，很明显，前馈投影的数量通常远远超过其反馈投影的数量。这一一般规则也适用于丘脑的背外侧膝状核 (dLGN)，其中约 30% 的中继细胞突触输入是由皮质丘脑 (CT) 锥体细胞产生的，而只有约 10% 的前馈输入来自视网膜神经节细胞。这种对最早的视觉处理阶段之一的解剖学上的大规模反馈投影如何影响 dLGN 的表征以及丘脑皮质环路中的计算，迄今仍未完全了解。拟议的研究是一个后续项目，继续围绕皮质丘脑反馈对早期视觉系统信息处理的影响。虽然我们在上一个资助期间的研究提供了对丘脑 CT 反馈回路的视网膜专题组织以及 CT 反馈效应在塑造空间处理（即促进和抑制）中的双重性质的见解，但我们后续提案的中心目标是阐明丘脑-皮质-丘脑相互作用中前馈和反馈处理的时空动态。特别是，我们将（1）分离 CT 反馈在 dLGN 和 visTRN 中的时间影响，我们将（2）通过使用 CT 反馈终端的通路特异性、光遗传学抑制以及丘脑和皮质的同步记录来研究 CT 反馈在塑造时空选择性中的作用，并且我们将（3）探讨 CT 反馈在丘脑皮质节律中的作用 总之，这项研究有望有助于回答直接兴奋性和间接抑制性 CT 反馈如何动态相互作用以调节丘脑皮质视觉处理的基本问题。