Fig. 5: NI NMB neurons receive inputs from brain areas associated with arousal and locomotion.

a The strategy for monosynaptic retrograde tracing of NI NMB neurons. b The expression pattern of TVA-mCherry (red) and RV-GFP (green) at the injection site within the NI. Dual labeled cells indicate starter cells competent for retrograde transsynaptic traversal. c Ratio of total retrogradely-labeled neurons in various upstream stations of NI NMB neurons (n = 4 mice). d Schematic showing the inputs of NI NMB neurons. e Schematic diagram showing terminal photostimulation of the upstream neurons and whole-cell patch recording of the NI NMB⁺ cells. f Presynaptic RV⁺ cells in the MS. g Postsynaptic responses from a NMB⁺ neuron in the NI following photostimulation of ChR2⁺ MS neuron axonal terminals under the conditions of control (latency, 8.1 ± 0.8 ms), drug applications, and wash. Postsynaptic current was measured holding at −65 mV. The right panel shows the summary effect of DNQX and the addition of Gabazine (n = 6 NMB⁺ cells from 2 mice). h, i Presynaptic RV⁺ cells in the LH (h) and the physiological effect of photostimulating ChR2-expressing LH axonal terminals on NI NMB neurons (i; latency, 6.6 ± 0.6 ms). Right panel in (i) shows the drug effects (n = 9 NMB⁺ cells from 2 mice). j, k Presynaptic RV⁺ cells in the LHb (j) and the physiological effect of activating LHb axonal terminals on NI NMB neurons (k; latency, 8.5 ± 1.0 ms; n = 6 NMB⁺ cells from 2 mice). l, m Presynaptic RV⁺ cells in the IPN (l) and the physiological effect of activating IPN axonal terminals on NI NMB neurons (m; latency, 6.2 ± 1.2 ms; n = 6 NMB⁺ cells from 2 mice). Error bars (c, g, i, k, m) indicate SEM. Scale bars = 200 µm (b, f, h, j, and l). Source data are provided as a Source Data file.