The Mediodorsal Thalamus Drives Feedforward Inhibition in the Anterior Cingulate Cortex via Parvalbumin Interneurons
The Mediodorsal Thalamus Drives Feedforward Inhibition in the Anterior Cingulate Cortex via Parvalbumin Interneurons
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DOI：
10.1523/jneurosci.4565-14.2015
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发表时间：
2015-04-08
影响因子：
5.3
通讯作者：
Li, Bo
中科院分区：
文献类型：
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作者：
Delevich, Kristen;Tucciarone, Jason;Li, Bo
虽然内侧前额叶皮质(MPFC)的经典定义是它与丘脑内侧背核(MD)的相互联系，但MD和mPFC之间的信息传递的本质却鲜为人知。在感觉丘脑皮质通路中，丘脑重新募集由快速放电的可能的小白蛋白表达(PV)中间神经元介导的前馈抑制是使皮质神经元能够以高时间保真度代表感觉刺激的关键特征。MD(一种不接受外周直接输入的高阶丘脑核团)向mPFC的投射是否存在类似的电路机制尚不清楚。在这里，我们在小鼠身上展示了来自MD的输入在mPFC的背侧前扣带皮质(DACC)亚区驱动双突触前馈抑制。特别是，我们证明了来自MD神经元的轴突直接突触并兴奋PV中间神经元，而PV中间神经元反过来介导了对dACC第三层锥体神经元的前馈抑制。DACC的这种前馈抑制限制了锥体神经元整合兴奋性突触输入和放电动作电位的时间窗口，但其方式比感觉皮质允许更大的灵活性。这些发现为理解MD-PFC通路功能在认知中的作用提供了基础。
Although the medial prefrontal cortex (mPFC) is classically defined by its reciprocal connections with the mediodorsal thalamic nucleus (MD), the nature of information transfer between MD and mPFC is poorly understood. In sensory thalamocortical pathways, thalamic recruitment of feedforward inhibition mediated by fast-spiking, putative parvalbumin-expressing (PV) interneurons is a key feature that enables cortical neurons to represent sensory stimuli with high temporal fidelity. Whether a similar circuit mechanism is in place for the projection from the MD(a higher-order thalamic nucleus that does not receive direct input from the periphery) to the mPFC is unknown. Here we show in mice that inputs from the MD drive disynaptic feedforward inhibition in the dorsal anterior cingulate cortex (dACC) subregion of the mPFC. In particular, we demonstrate that axons arising from MD neurons directly synapse onto and excite PV interneurons that in turn mediate feedforward inhibition of pyramidal neurons in layer 3 of the dACC. This feedforward inhibition in the dACC limits the time window during which pyramidal neurons integrate excitatory synaptic inputs and fire action potentials, but in a manner that allows for greater flexibility than in sensory cortex. These findings provide a foundation for understanding the role of MD-PFC circuit function in cognition.