Fig. 2. Circadian pattern of wheel-running activity in control (C, open symbols) and activity-selected mice (S, closed symbols) running spontaneously (circles) or running for food (triangles). Each symbol plots the mean distance ran in hourly bins (e.g. bin 12=from 12:00 until 13:00). Vertical bars are inter-individual s.e.m. The black bar on top represents the dark phase.