Fig. 4. Activation of SC drives activity in POm.

a Left: coronal section of thalamus showing SC axons (in green) in POm. Scale bar 500 µm. DAPI in blue. Middle: somatosensory thalamus showing the region delineated by the white square in the left image. Scale bar 100 µm. Right: higher magnification of the regions delineated by the white squares in the middle image showing SC axons in POm but not VPM. Scale bars 40 µm. b Schematic of the experimental arrangement. After cutting the facial nerves, recordings were made from the POm while activating SC optogenetically through an optic fiber in the presence or absence of whisker vibration. c Raster plot (top) and peri-stimulus time histogram (bottom) of an extracellular array recording from a POm neuron (2407 µm from the surface of the brain) showing increased action potential firing in response to SC activation. d Spiking of POm neurons (n = 38) increases significantly during light activation of SC. Asterisk represents p < 0.001 (Two-sided paired t-test). e Raster plot of action potential firing in a POm neuron (same neuron as c) during whisker movement of different amplitude alone (orange; left) and with light activation of SC (green; right). f Pooled data showing the impact of SC activation (green) on the whisker input–output relationship of whisker responsive POm neurons (orange). Only neurons that were responsive to both whisker and SC stimulation were included in this analysis (n = 15). Spiking of each neuron was normalized to the maximum response to whisker stimulation alone. Error bars represent SEM. Source data are provided as a Source Data file.