The fictive swim rhythm can be reset by a foot tap during the HE phase. A, Recordings from two episodes of fictive swimming in one animal are aligned by the timing of the swim stimulation (with identical stimulation parameters). Note that the upper (control, A1) fictive swim HF rhythm slightly led the lower (foot tap-episode, A2) HF rhythm until the foot tap occurred (red lines). After the foot tap, the lower HF rhythm consistently led the upper HF rhythm, showing that the fictive swim HF rhythm was reset by the foot tap and there was an extra HF burst at the end (asterisk). Across animals, the fictive swim cycle immediately after a foot tap was significantly briefer (means ± SD; Mann–Whitney test, p < 0.05) than fictive swim cycles from control episodes (B) and often briefer than the fictive swim cycles just before and just after the foot-tap cycle within the same fictive swim episode (C).