The relationship of the central motor pattern to the feeding cycle of Lymnaea stagnalis.

Electromyographic recordings from the buccal muscles of Lymnaea during feeding has shown that there are 4 component phases in the feeding cycle. Cinephotography of feeding cycles has confirmed that these correspond to protraction, 2 phases of retraction, and an inactive phase. The 4 phases of muscle activity can also be related to the cycle of neural activity described previously (Benjamin & Rose, 1979). Thus types 6, 4 group, and type 8 cells are motoneurones involved in protraction and the two retraction phases, while the type 5 cell fires in the inactive period. The combination of physiological and anatomical approaches has led to the suggestion that the single and double input cells described by Benjamin & Rose (1979) are involved with the control of buccal and oesophageal activity respectively.