title: Control of feeding movements in the freshwater snail Planorbis corneus. III. Organization of the feeding rhythm generator.
abstract: (1) Neurons of different groups (for group classification, see Arshavsky et al. 1988a) have been polarized through an intracellular recording microelectrode in Planorbis corneus buccal ganglia during feeding rhythm generation. Group 1 neurons, active in the quiescence (Q) and in the protractor (P) phases of the cycle, and also group 2 and 4 neurons, active in the retractor (R) phase, have proved to be "influential", i.e., altering the rhythm generator operation. (2) Injection of a depolarizing current into group 1 neurons caused an increase of the rate of depolarization that neurons of this group exhibit in the Q- and P-phases of the feeding cycle. As a result, Q-phase shortened, the P-phase became longer, and the feeding rhythm accelerated. Opposite effects occurred when a hyperpolarizing current was injected into group 1 neurons. In some of the experiments, the hyperpolarization of group 1 neurons resulted in cessation of both their activity and the activity of all other protractor neurons. As a result, the P-phase of the cycle disappeared, i.e., the rhythm generator transited from A mode of operation to B mode. (3) With hyperpolarization of individual group 2 or 4 neurons, excitation of the R-phase neurons was delayed and the feeding rhythm phase shifted. This delay was accompanied by the enhanced activity of protractor neurons. (4) A generator model is considered in which two groups (1 and 2) of endogeneously active neurons are coordinated by the excitatory effect of group 1 on group 2 and the inhibitory action of group 2 on group 1. (5) Evidence is given that the different modes of rhythm generator operation (A, B and C, see Arshavsky et al. 1988a) are determined by different tonic inflow to group 1 neurons.
authors: Institute of Problems of Information Transmission, Academy of Sciences of the USSR, Moscow.
authors: Arshavsky YuI
authors: T G
authors: TG
authors: Deliagina
authors: G N
authors: GN
authors: Orlovsky
authors: Panchin YuV
mesh_terms: D000200:Action Potentials; D000818:Animals; D005247:Feeding Behavior / Q000502:physiology*; D005724:Ganglia / Q000502:physiology*; D066298:In Vitro Techniques; D009068:Movement; D009474:Neurons / Q000145:classification / Q000502:physiology; D010507:Periodicity; D012908:Snails / Q000502:physiology*