Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC/INSERM UMR-S 975, CNRS UMR 7225, Hôpital Pitié-Salpêtrière, Paris, France.
J Physiol. 2011 Jan 15;589(Pt 2):263-81. doi: 10.1113/jphysiol.2010.199646.
The dorsolateral striatum is critically involved in the execution and learning of sensorimotor tasks. It is proposed that this striatal function is achieved by the integration of convergent somatosensory and motor corticostriatal (CS) inputs in striatal medium-spiny neurons (MSNs). However, the cellular mechanisms of integration and propagation of somatosensory information in the CS pathway remain unknown. Here, by means of in vivo intracellular recordings in the rat, we analysed how sensory events generated by multi-whisker deflection, which provide essential somaesthetic information in rodents, are processed in contralateral barrel cortex layer 5 neurons and in the related somatosensory striatal MSNs. Pyramidal layer 5 barrel cortex neurons, including neurons antidromically identified as CS, responded to whisker deflection by depolarizing post-synaptic potentials that could reliably generate action potential discharge. In contrast, only half of recorded somatosensory striatal MSNs displayed whisker-evoked synaptic depolarizations that were effective in eliciting action potentials in one-third of responding neurons. The remaining population of MSNs did not exhibit any detectable electrical events in response to whisker stimulation. The relative inconstancy of sensory-evoked responses in MSNs was due, at least in part, to a Cl(-)-dependent membrane conductance concomitant with the cortical inputs,which was probably caused by whisker-induced activation of striatal GABAergic interneurons. Our results suggest that the propagation of whisker-mediated sensory flow through the CS pathway results in a refinement of sensory information in the striatum, which might allow the selection of specific sets of MSNs that are functionally significant during a given somaesthetic-guided behaviour.
背外侧纹状体在执行和学习感觉运动任务中起着至关重要的作用。有人提出，这种纹状体功能是通过汇聚的躯体感觉和皮质纹状体（CS）输入在纹状体中型棘突神经元（MSNs）中的整合来实现的。然而，CS 通路中躯体感觉信息的整合和传播的细胞机制仍然未知。在这里，通过在大鼠体内进行的细胞内记录，我们分析了多胡须偏转产生的感觉事件如何在对侧桶状皮层 5 层神经元和相关的躯体感觉纹状体 MSNs 中被处理，这些感觉事件为啮齿动物提供了基本的躯体感觉信息。包括经逆行鉴定为 CS 的神经元在内的皮层 5 层桶状皮层神经元，对胡须偏转产生去极化的突触后电位，这些电位可以可靠地产生动作电位放电。相比之下，只有一半记录的躯体感觉纹状体 MSNs 显示出胡须诱发的突触去极化，这些去极化在三分之一的反应神经元中有效引发动作电位。其余的 MSNs 群体对胡须刺激没有表现出任何可检测的电活动。MSNs 中感觉诱发反应的相对不稳定性至少部分是由于与皮质输入伴随的 Cl(-)依赖性膜电导所致，这可能是由于胡须诱导的纹状体 GABA 能中间神经元的激活引起的。我们的结果表明，胡须介导的感觉流通过 CS 通路的传播导致了纹状体中感觉信息的细化，这可能允许选择在特定躯体感觉引导行为中具有功能意义的特定 MSNs 集。
