Fig. 5: S1/S2, cALM and ThalALM inputs connect to all response profiles in ALM.
From: Thalamus-driven functional populations in frontal cortex support decision-making
a, Measuring long-range input connectivity using ChR2-tagging. b, Top: example neurons with short-latency responses to photostimulation of S1/S2 axons (tagged). Bottom: example ALM neurons unresponsive or suppressed by photostimulation (nontagged). Photostimulus, 1-ms pulses, 30 mW. c, Top: average response of tagged (n = 172) and nontagged neurons (n = 1,487). S1/S2, cALM and ThalALM axonal photostimulation data are combined. Bottom: response magnitude and latency of tagged neurons. Box and whisker plot shows median, 25/75th percentiles and most extreme data points not considered as outliers. d, ChR2-assisted circuit mapping. e, Calibration recordings from ALM. Left: example EPSPs. S1/S2 axonal photostimulation. Application of TTX left EPSP intact in a connected neuron (top). TTX abolished EPSP in an unconnected neuron (bottom). Right: mean EPSP before and after TTX for all tested neurons. Photostimulation power, 20 mW. f, EPSP latency of neurons verified to be connected or unconnected using TTX. Mean ± s.d. across neurons (S1/S2, n = 17; cALM, n = 17; ThalALM, n = 13). A latency threshold (5 ms) could differentiate connected and unconnected neurons. Dots, individual neurons. Unconnected neurons with no EPSPs are shown on top. g, Left: ALM neurons connected to S1/S2 (top), cALM (middle) and ThalALM inputs (bottom) shown in the t-SNE. Colored dots, connected neurons measured from ChR2-tagging (red) and ChR2-assisted circuit mapping (black); gray dots, all neurons in the dataset. Only a subset of the neurons are tested for input connectivity. Right: fraction of connected neurons relative to all tested neurons within each functional population (Fig. 3e). Box and whisker plot shows median, 25/75th percentiles and most extreme data points not considered as outliers (bootstrap, Methods). h, S1/S2, cALM and ThalALM inputs differed in strength. Left: connection probability from ChR2-assisted circuit mapping. Numbers on each bar indicate the number of tested neurons. Right: light-induced EPSP in the connected neurons. Mean ± s.e.m. across neurons (dots). S1/S2, n = 43; cALM, n = 53; ThalALM, n = 45. Only a subset of the neurons in panel h are tested in behavior, shown in panel g. See Extended Data Fig. 8. VM, ventral-medial nucleus.
