Central pattern generator for swimming in Melibe

• DOI: 10.1242/jeb.01500
• Publication Date: 2005-03-21T23:13:21Z
• Authors: Stuart Thompson; Winsor H. Watson
• Keywords: Interneuron; Hyperpolarization

SUMMARY The nudibranch mollusc Melibe leonina swims by bending from side to side. We have identified a network of neurons that appears constitute the central pattern generator (CPG) for this locomotor behavior, one only few such networks be described in cellular detail. consists two pairs interneurons, termed `swim interneuron 1' (sint1) and`swim 2' (sint2), arranged around plane bilateral symmetry. Interneurons on brain, which includes paired cerebral, pleural and pedal ganglia, coordinate movements toward same communicate via non-rectifying electrical synapses. opposite sides brain antagonistic over mutually inhibitory synaptic pathways. Several criteria were used identify members swim CPG, most important being ability shift phase swimming behavior quantitative fashion briefly altering firing an individual neuron. Strong depolarization any interneurons produces ipsilateral movement during several components motor act occur sequence. hyperpolarization causes stop leaves animal contracted duration hyperpolarization. four make appropriate connections with motoneurons, exciting synergists inhibiting antagonists. Finally, these are found set properties spite concerted efforts sample widely CNS. This led us conclude cells CPG swimming. While sint1 sint2 work together swimming, they play different roles generation other behaviors. Sint1 is normally silent when crawling surface but it depolarizes begins fire strong bursts once foot dislodged swim. Sint2 also fires not non-swimming animals. Instead activity correlated turning as crawls surface. suggests system organized hierarchy alternating characteristic emerge bound together.