Figure 3: Mean basic clock period 1/λ (s), by PI length. Error bars present the standard deviations. Broken lines indicate 3/2.1/ λ0 and 2/3. 1/ λ0, where 1/ λ0 is the basic period of the first PI-30 in sessions 21 through 30. The top and bottom panels present these values for groups RatsA and RatsB, respectively.