Control of feeding movements in the freshwater snail Planorbis corneus

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.

Neurons versus Networks: The Interplay between Individual Neurons and Neural Networks in Cognitive Functions

“…The former view dominated and was supported by numerous computational models, which reproduced the generation of sustained rhythmic activity from interactions among neuron-like elements (Friesen and Stent 1978; Psujek and others 2006; Roberts and Tunstall 1990; Rybak and others 2006). However, this purely connectionist view was revised based on experimental observations obtained with both vertebrates and invertebrates (Arshavsky and others 1986; Arshavsky and others 1988; Brocard and others 2010; Elson and Selverston 1992; Hochman and others 1994; Li and others 2010; Masino and others 2012; Onimaru and others 1995; Panchin and others 1993; Peña and others 2004; Tell and Jean 1993; Wallén and Grillner 1987; Wilson and others 2005). It has been shown that rhythm generation is based mainly on the pacemaker activity of specific groups of interneurons that continue to produce rhythmic activity after being isolated from synaptic inputs.…”

Hydrobia Ulvae (Gastropoda: Prosobranchia): a New Model for Regeneration Studies

“…In most gastropods (Cohen et al, 1978;Benjamin and Rose, 1979;Kater, 1974;Arshavsky et al, 1988; Categories are as in Fig. 4; N values are given in Table 1.…”

Comparative Neurobiology of Feeding in the Opisthobranch Sea Slug, <i>Aplysia</i>, and the Pulmonate Snail, <i>Helisoma</i>: Evolutionary Considerations

“…2 B 2 ). The most striking physiological characteristic of the neurons in the B101 cluster was their 'influential' capacity [terminology of Arshavsky et al, 1988] in the control of phase 3 (odontophore hyperretraction). Miller et al, 1994].…”

“…A sample would include Planorbis [Arshavsky et al, 1988], Limax [Gelperin et al, 1978], Helix [Peters and Altrup, 1984], Achatina [Yoshida and Kobayashi, 1992], Navanax [Cappell et al, 1989], Tritonia [Bulloch and Dorsett, 1979], Pleurobranchaea [Gillette and Gillette, 1983], and Clione [Moroz et al, 2000]. Each of these feeding motor systems contains many uniquely identifiable neurons.…”