McGovern Institute for Brain Research, Cambridge, United States.
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States.
Elife. 2020 Oct 26;9:e62554. doi: 10.7554/eLife.62554.
The thalamus engages in sensation, action, and cognition, but the structure underlying these functions is poorly understood. Thalamic innervation of associative cortex targets several interneuron types, modulating dynamics and influencing plasticity. Is this structure-function relationship distinct from that of sensory thalamocortical systems? Here, we systematically compared function and structure across a sensory and an associative thalamocortical loop in the mouse. Enhancing excitability of mediodorsal thalamus, an associative structure, resulted in prefrontal activity dominated by inhibition. Equivalent enhancement of medial geniculate excitability robustly drove auditory cortical excitation. Structurally, geniculate axons innervated excitatory cortical targets in a preferential manner and with larger synaptic terminals, providing a putative explanation for functional divergence. The two thalamic circuits also had distinct input patterns, with mediodorsal thalamus receiving innervation from a diverse set of cortical areas. Altogether, our findings contribute to the emerging view of functional diversity across thalamic microcircuits and its structural basis.
丘脑参与感觉、动作和认知，但这些功能的基础结构还了解甚少。丘脑对联合皮层的神经支配靶向几种中间神经元类型，调节动力学并影响可塑性。这种结构-功能关系是否与感觉丘脑皮质系统不同？在这里，我们系统地比较了小鼠中一个感觉和一个联合丘脑皮质回路的功能和结构。增强联合结构内侧丘脑的兴奋性导致前扣带回活动主要受抑制支配。同样增强内侧膝状体的兴奋性强烈驱动听觉皮层的兴奋。从结构上看，膝状体内侧的轴突以优先的方式和更大的突触末端支配兴奋性皮质靶标，为功能发散提供了一个可能的解释。这两个丘脑回路也具有不同的输入模式，其中内侧丘脑接受来自多个皮质区域的神经支配。总的来说，我们的发现有助于对丘脑微回路的功能多样性及其结构基础的新兴观点。
