Figure 3. Robust locomotor behavior rhythms in Per1^−/− mice persist after ocular enucleation and in the absence of wheel-running activity feedback.

Double-plotted actograms (5-min bins) of locomotor activity of male Per1^−/− mice (x-axis: time in hours; y-axis: days). A, B. Wheel-running activity was recorded from Per1^−/− mice (n = 2) maintained in 12L∶12D (LD) and ocular nucleation was performed (indicated by asterisks). Two days after surgery, mice were released into constant darkness (DD). C, D. Per1^−/− mice (n = 5) were housed in cages with locked running wheels (wheels were present but could not rotate), maintained in 12L∶12D and then released into DD. General activity was continuously monitored with passive infrared sensors.