Fig. 2: Ex vivo whole-cell recordings in brain slices of POm-FO and POm-HO inputs to excitatory neurons across layers in wS2.

a Schematic showing the strategy used to selectively express ChR2-eYFP in FO or HO subdivisions of POm. Method used to activate thalamocortical axons expressing channelrhodopsin-2 in order to evoke postsynaptic potentials in the somatosensory cortex is illustrated. A 470 nm wavelength light was delivered with a LED light source coupled with a 1 mm optic fiber onto wS2. Inset: Two-photon microscopy image of an in vitro whole-cell patch–clamp recording of two neurons filled with Alexa 594. b Confocal z-projection of wS2 in a parasagittal slice after fixation. ChR2-eYFP was expressed in POm-FO axons, and recorded neurons were filled with biocytin followed by staining with streptavidin conjugated to Alexa 647. This experiment was repeated in three mice with similar results. c Light-evoked excitatory postsynaptic potentials (EPSPs) from recorded neurons labeled in b following 1 ms light pulses. d Top: Peak amplitude of EPSPs evoked by optogenetic stimulation of POm-FO axons recorded in cortical excitatory neurons (N = 3 mice, n = 39 neurons) across different layers in wS2. On each box, central mark indicates the median and edges indicate 25th and 75th percentiles. The whiskers extend from the minimum data point comprised within 1.5× of the interquartile range to the 25th percentile and from the maximum data point comprised within 1.5× of the interquartile range to the 75th percentile. Bottom: same responses normalized to the average peak EPSP recorded in the main input layer (L4) for each experiment. e–g Same as b–d but for POm-HO axon stimulation during whole-cell recording of neurons in wS2 (N = 3 mice with similar results, n = 34 neurons). Here, EPSPs were normalized to the average peak EPSPs from L5A neurons for each experiment.