Cerebral ganglion of Aplysia: Cellular organization and origin of nerves

Abstract

Abstracto1.The neuronal organization and the origin of the nerves of the cerebral ganglion of Aplysia californica was investigated.2.A functional nomenclature was given to all the cerebral nerves and connectives.3.Seven bilaterally symmetrical pairs of neuron clusters and an 8th asymmetric cluster on the right side of the cerebral ganglion can be identified on the basis of their physical properties.4.Intracellular recordings from the constituent neurons (total of 235 ganglion cells) suggest that the individual clusters are also distinct in their physiological properties.5.Antidromic and orthodromic responses from electrical stimulation and filling with CoCl2 by axonal iontophoresis provided information on the central origin and projection of the cerebral nerves.6.Neither origin, nor projection of individual cerebral nerves, appeared to be restricted to one cluster. There were, however, distinct patterns of cerebral distribution for each nerve.7.The majority of cerebral neurons were multiaxonal sending processes to various regions of the body and to other central ganglia.8.It is suggested that the cerebral ganglion is in a position to exert a modulating influence on functions of the rest of the Aplysia nervous system. The neuronal organization and the origin of the nerves of the cerebral ganglion of Aplysia californica was investigated. A functional nomenclature was given to all the cerebral nerves and connectives. Seven bilaterally symmetrical pairs of neuron clusters and an 8th asymmetric cluster on the right side of the cerebral ganglion can be identified on the basis of their physical properties. Intracellular recordings from the constituent neurons (total of 235 ganglion cells) suggest that the individual clusters are also distinct in their physiological properties. Antidromic and orthodromic responses from electrical stimulation and filling with CoCl2 by axonal iontophoresis provided information on the central origin and projection of the cerebral nerves. Neither origin, nor projection of individual cerebral nerves, appeared to be restricted to one cluster. There were, however, distinct patterns of cerebral distribution for each nerve. The majority of cerebral neurons were multiaxonal sending processes to various regions of the body and to other central ganglia. It is suggested that the cerebral ganglion is in a position to exert a modulating influence on functions of the rest of the Aplysia nervous system.