Figure 1. The β2 subunit is required for SCN neuronal firing rhythmicity and circadian behaviour.

(a) Representative spontaneous action potential activity recorded for 3 days on a multielectrode array from WT SCNs. Firing rate shows a robust peak-to-trough difference. (b) β2 KO SCN activity. Firing amplitude and rhythmicity were reduced. (c) The percentage of recordings within the SCN exhibiting rhythmic firing is decreased in β2 KO compared with WT and β4 KO SCNs (n=8, 11 and 10 SCN slices, respectively). (d) χ² periodogram analysis of action potential activity. χ² circadian peak amplitudes were reduced in β2 KO compared with WT and β4 KO SCNs. (e) Multiunit firing frequency from the peak and trough of rhythmic recordings, or from arrhythmic recordings. β2 KO firing is reduced during the peak. (f) Locomotor wheel running activity from a representative WT mouse. (g) β2 KO actogram. (h) χ² periodogram analysis of wheel behaviour. Dotted line denotes 3,000 (amplitude). (i) β2 KO mice re-entrained to a 6 h phase advance of the light–dark cycle faster than WT. (j) Exposure to a light pulse at CT16 caused a greater phase delay in β2 KO compared with WT. Representative actograms for i and j are in Supplementary Fig. 1. All values are mean±s.e.m. *P<0.05, Bonferroni post hoc (c–e) or t-test (i–j).