Fig. 3. Recordings of circadian wheel-running activity and plots of activity onsets from cockroaches kept in constant darkness. (A,B) After injection of 200 fmol of Mas-allatotropin in 2 nl of saline at CT15:30 h of day 16 (arrowhead), regression analysis through consecutive activity onsets (B) revealed a phase delay of 3.05 circadian hours (h_CT) after the injection. (C,D) Injection of 50 pmol of GABA in 0.5 nl of saline with blue food dye at CT 17:30 h of day 9 (arrowhead) induced a phase advance of 3.15 circadian hours. Neither experiment had any effect on the period of the activity rhythm, after a new stable state, through several transient states (days 17-28 in A; days 10-18 in C), had been established. CT, circadian time.