Pii: S0304-3940(02)00468-8

The present study examined the correlation between the level of activity neuron B52 and the transition from protraction to retraction phases of buccal motor patterns (BMPs) and the termination of the BMPs. The level of activity in B52 during the protraction phase was positively correlated with the duration of that phase. A second burst of activity in B52 was associated with the termination of the retraction phase. An apparent monosynaptic inhibitory connection from B52 to B64, may mediate the effects of B52. The first burst of activity in B52 delays the onset of activity in B64, thereby prolonging the protraction phase, and the second burst inhibits activity in B64, thereby terminating the retraction phase. These results suggest that activity in B52 may contribute to switching between ingestion-like and rejection-like BMPs by regulating both phase transition and termination of BMPs. q 2002 Elsevier Science Ireland Ltd. All rights reserved.