Phylogenetic and individual variation in gastropod central pattern generators

Abstract

Gastropod molluscs provide a unique opportunity to explore the neural basis of rhythmic behaviors because of the accessibility of their nervous systems and the number of species that have been examined. Detailed comparisons of the central pattern generators (CPGs) underlying rhythmic feeding and swimming behaviors highlight the presence and effects of variation in neural circuits both across and within species. The feeding motor pattern of the snail, Lymnaea, is stereotyped, whereas the feeding motor pattern in the sea hare, Aplysia, is variable. However, the Aplysia motor pattern is regularized with operant conditioning or by mimicking learning using the dynamic clamp to change properties of CPG neurons. Swimming evolved repeatedly in marine gastropods. Distinct neural mechanisms underlie dissimilar forms of swimming, with homologous neurons playing different roles. However, even similar swimming behaviors in different species can be produced by distinct neural mechanisms, resulting from different synaptic connectivity of homologous neurons. Within a species, there can be variation in the strength and even valence of synapses, which does not have functional relevance under normal conditions, but can cause some individuals to be more susceptible to lesion of the circuit. This inter- and intra-species variation provides novel insights into CPG function and plasticity.

Comparative Mapping of GABA‐Immunoreactive Neurons in the Buccal Ganglia of Nudipleura Molluscs

“…Gastropod feeding strategies are highly diverse and include rasping, grazing, sucking, suspension feeding, cutting, and hunting (Audesirk and Audesirk, ; Chase, ; Sakurai and Katz, ). Although there are differences in choice of prey and feeding habits of the species in this study, feeding in Melibe differs drastically in that it is highly specialized and unique in Gastropoda (Hurst, ; Watson and Trimarchi, ).…”

Evolution of central pattern generators and rhythmic behaviours

“…In many invertebrates, individual neurons can be identified from animal to animal within a species, allowing the neural circuits to be determined with cellular precision. Moreover, homologous neurons can be identified across species, permitting comparative analyses of CPG circuits and the rhythmic behaviours that they produce [4,5]. Thus CPGs provide extraordinary opportunities to study the evolution of behaviour and neural circuits.…”

Deviating from the Norm: Peculiarities of Aplysia cf. californica Early Cleavage Compared to Traditional Spiralian Models

“…Remarkably, we have also observed this atypical cleavage pattern in other anaspideans such as Stylocheilus striatus , Dolabrifera dolabrifera , Dolabella auricularia , and Aplysia dactylomela (unpublished data), suggesting that this pattern of cleavage may be conserved in the Anaspidea. Previous studies of the phylogenetic relationships of opisthobranchs using morphological and molecular data have suggested that the Anaspidea may be one of the most derived clades within the group (Wägele et al., ; Zapata et al., , ; Sakurai and Katz, ; Sevigny et al., ), so it is not surprising to see a most deviate pattern of cleavage in this order.…”