A, a tIN shows tonic depolarisation from the resting potential (dotted line) and receives rhythmic on-cycle IPSPs in phase with ipsilateral ventral root activity (vr) at the beginning, during, and at the end of a fictive swimming episode evoked by dimming the light. The membrane potential returns to rest about 200 ms after swimming ends. B, histogram showing that different tINs receive IPSPs mainly on-cycle (open bars) or mid-cycle (black bars). Data are from 10 swimming cycles for each of 20 tINs, bin size: 0.05.