Cortical dendrite and touch
There is as yet no consensus concerning the neural basis of perception and how it operates at a mechanistic level. We previously showed that active calcium currents in the apical dendrites of a subset of layer 5 (L5) pyramidal neurons in primary somatosensory cortex (S1) in mice is correlated with the threshold for perceptual detection of whisker deflections. L5 neurons come in two classes that target either other cortical or subcortical areas, routing the output of cortical columns to distinct downstream targets. By taking advantage of transgenic mouse lines for these L5 subclasses, we found that the activation of apical dendrites in subcortically-projecting L5 neurons 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.