Amplitude of the SCN Clock Enhanced by the Behavioral Activity Rhythm
Figure 2
Time course of suppressions of SCN electrical activity during spontaneous behavioral activity.
The start of behavioral activity is characterized by an acute drop of SCN firing rate. Decreased levels of SCN electrical activity are typically sustained throughout the duration of behavioral activity. Representative examples of different durations are shown. Behavioral activity and associated suppressed levels of SCN electrical activity last for approximately (a) 10 s, (b) 10 min, and (c) 30 min. Behavioral activity as detected by the passive infrared detector is plotted in the lower bar (all-or-nothing modus). Note that the PIR detector does not detect all behavioral activity which became apparent from the video recordings. Suppressions that lasted <1 min were observed in ∼20% of the cases, the occurrence of suppressions of 1–25 min was ∼ 65%, and the occurrence of long suppressions of >25 min was ∼15%. In each figure, the X-axis represents time (scale unit is given by the bar in the figure). Suppressions of all shown examples occurred between Zeitgeber Time (ZT) 3 and ZT10) under LD conditions. The Y-axis shows SCN firing rate (Hz). Bin size is 10 s.