Fig. 1

Effect of LHb electrolytic lesions on mechanical stimulation (MS)-induced inhibition of cocaine-enhanced 50 kHz USVs and locomotion. A Experiment schedule and electrolytic lesion of LHb stained with toluidine blue. B Schematic location of MS sites. The ulnar nerves (Ulna MS) or radial nerves (Rad MS) were stimulated with a mechanical instrument (MI). C Effect of MS on cocaine-induced 50 kHz ultrasonic vocalizations (USVs) in normal or LHb-lesioned rats. *p < 0.001, Control versus Ulna MS; ^#P < 0.001, LHb X + Ulna MS versus Ulna MS. n = 7–8 per group. D, E Schematics for USVs recordings in a sound-attenuating chamber (D) and representative spectrograms of 50 kHz USV following cocaine injection (E). F Effect of MS on cocaine-induced locomotor activity in normal or LHb-lesioned rats. *P < 0.001, Control versus Ulna MS; ^#P < 0.001, LHb + Ulna MS versus Ulna MS; ^$P < 0.01, Ulna MS versus Rad MS. G Representative moving tracks for 60 min after cocaine injection or MS (n = 6–7 per group). LHb, lateral habenula; Control, cocaine injection only in normal rats; Ulna MS, mechanical stimulation of ulnar nerve; LHb X + Ulna MS, mechanical stimulation of ulnar nerve after cocaine injection in the rats with electrolytic lesions of bilateral LHb; Rad MS, mechanical stimulation of radial nerve; S + Ulna MS, saline injection instead of cocaine and ulnar MS