Fig. 3.

DLaN did not alter the daytime spontaneous frequency rate (SFR) of SCN neurons measured in a brain slice preparation. (A) Extracellular recording techniques indicated that SCN neurons from the Cntnap2 KO (n = 101) exhibited a modestly reduced daytime (ZT 5–7) firing rate compared to WT (n = 102) controls (Mann-Whitney Rank Sum test with U = 2499, P < 0.001). (B) The distribution of SFR was shifted lower in the mutants with highly significant changes in the number of neurons firing at the 0–2 Hz rate (Z score = −6.050, P = 0.001). In a separate experiment (C), cell-attached recording techniques were used to measure the SFR of Cntnap2 KO and WT mice in brain slices prepared from mice held in normal LD and under DLaN. In WT mice (one-way ANOVA), there were significant differences (H = 19.744, P < 0.001) driven by a day/night difference in firing rate (Q = 4.418; P < 0.001). In Cntnap2 KO, the day/night difference was lost (H = 0.338; P < 0.953). If we consider only day-time firing rate, the WT exhibits significantly higher SFR (H = 11.722; P = 0.029) than the KO. There was no significant day/night difference in SFR under DLaN. In short, DLaN did not produce changes in SCN firing rate that we could measure in the slice preparation, but the Cntnap2 KO did show a reduced SCN output.