a, Histology of recording site. Arrowhead indicates the electrical lesion by tetrodes. b, Representative waveform clusters of two isolated LHb units in the respective four channels of a tetrode (left) and principal-component analysis (PCA) clustering display of these two units (right). c, ISIs between consecutive spikes in relation to their positions within the burst (120 bursts from in vitro recording). d, Example recording trace (upper) and spike train (bottom) of an irregular-firing LHb neuron from an in vivo recording. Bursts (blue sticks) are identified by ISI method (see Methods for details): 1, ISI to start burst; 2, ISI to end burst; 3, inter-burst interval. e, Histogram of ISI distribution (bin, 2.5 ms) from in vivo recording. f–i, Mean of total and tonic firing rates (f, h), intra- and inter-burst frequencies, and number of spikes per burst (g, i) of neurons recorded in vivo from control mice, CRS mice and CRS mice 1 h before and after ketamine injection (i.p., 10 mg kg–1). n = 35, 33 neurons (f, g) and 18, 18 neurons (h, i), 5 control and 5 CRS mice. j, STAs of neurons recorded in vivo from control mice, CRS mice, and CRS mice after ketamine injection (i.p., 10 mg kg–1). Note that the distance between the neighbouring troughs is around 140 ms (corresponding to 7 Hz) in CRS mice. Data are mean ± s.e.m.; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, n.s., not significant. Two-tailed Mann–Whitney test and unpaired t-test (f, g), two-tailed Wilcoxon matched-pairs signed rank test and paired t-test (h, i).