The output of cortical columns is routed to different downstream targets via distinct pathways: cortico-cortical and cortico-subcortical. It is as yet unclear what roles these pathways play in perception, and which cellular and circuit mechanisms regulate their gating. We recently showed that activation of the apical dendrites of layer 5 (L5) pyramidal neurons correlates with the threshold for perception, but these neurons come in two classes that target either other cortical or subcortical areas. In the present study, we took advantage of transgenic mouse lines for these L5 subclasses to determine their relative contributions to the perceptual process. We found that the activation of apical dendrites in neurons of the somatosensory cortex, which project to subcortical regions, almost exclusively determined the detection of tactile stimuli in mice. Our results suggest that dendritic activation drives context-dependent interactions between cortex and subcortical regions, including the higher-order thalamus, superior colliculus and striatum, which are crucial for perception.

皮质柱的输出通过不同的途径路由至不同的下游目标：皮质-皮质和皮质-亚皮质。尚不清楚这些途径在感知中起什么作用，以及哪些细胞和电路机制调节其门控。我们最近显示，第5层（L5）锥体神经元的顶端树突的激活与感知阈值相关，但是这些神经元分为两类，分别针对其他皮质或皮质下区域。在本研究中，我们利用这些L5亚类的转基因小鼠品系来确定它们对知觉过程的相对贡献。我们发现，在体感皮层神经元的顶突向树突的激活（投射到皮层下区域）几乎完全决定了小鼠触觉刺激的检测。