a–d, I–V plots (a), input resistance (b), intra-burst frequency (c) and inter-burst frequency (d) for LHb neurons in brain slices from mice and rats. Note that intra-burst frequency (c) but not inter-burst frequency (d) reversely correlates with RMPs. n = 20 neurons per group, 5 wild-type and 3 cLH rats (b); n = 53 neurons, 8 mice and 12 rats (c, d). e–i, Burst duration in animal models of depression recorded in brain slices in vitro (e–g) and in behaving animals in vivo (h, i). e, Representative trace of a typical burst in an in vitro recording. It consists of a depolarizing wave and a high-frequency train of action potentials. The duration of the line indicated by the black arrow at half-maximum amplitude of the area under the red dash line is defined as the half width of burst duration; the duration between the first and last shoots (intra burst spikes) within one burst is defined as the shoot duration. f, g, Half widths of burst duration (f) and shoot duration (g) do not differ between cLH and wild-type rats. n = 10, 20 neurons, 7 wild-type and 5 cLH rats. h, Representative trace of an LHb neuron (pink shades indicate burst events) recorded in vivo. An enlarged view of a typical burst on the right shows the definition of burst duration, which is the time interval between the first and last spike within the same burst. i, Burst duration of LHb neurons from in vivo recording do not differ between control and CRS mice. n = 35, 33 neurons, 5 control and 5 CRS mice. Data are mean ± s.e.m.; n.s., not significant. Two-tailed unpaired t-test (b, f, g) and Mann–Whitney test (i).