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Cumulative depolarization of Hermissenda type B photoreceptors, a short-term neural correlate of associative learning, was produced by simulating associative training in the isolated nervous system (in vitro conditioning). This simulation entailed stimulation and recording from three classes of neurons normally affected by the associative training(More)
Learning behavior similar to vertebrate classical conditioning was demonstrated for the mollusc Hermissenda crassicornis. Postsynaptic membrane changes within well-defined neural systems that mediate the learning play a casual role in recording the learned association for later recall. Specific ionic currents in neural tissue undergo transformations lasting(More)
A single identified neuron was repeatedly isolated by axotomy from the central nervous system of the nudibranch mollusk Hermissenda crassicornis. An early voltage-dependent outward K+ current of this neuron was reduced and more rapidly inactivated for animals previously trained with paired but not randomized light and rotation. Since this current change can(More)
Two-microelectrode voltage clamp studies were performed on the somata of Hermissenda Type B photoreceptors that had been isolated by axotomy from all synaptic interaction as well as any impulse-generating (i.e., active) membrane. In the presence of 2-10 mM 4-aminopyridine (4-AP) and 100 mM tetraethylammonium ion (TEA), which eliminated two previously(More)
Intradendritic recordings in Purkinje cells from a defined area in parasaggital slices of cerebellar lobule HVI, obtained after rabbits were given either paired (classical conditioning) or explicitly unpaired (control) presentations of tone and periorbital electrical stimulation, were used to assess the nature and duration of conditioning-specific changes(More)
We made intradendritic recordings in Purkinje cells (n = 164) from parasaggital slices of cerebellar lobule HVI obtained from rabbits given paired presentations of tone and periorbital electrical stimulation (classical conditioning, n = 27) or explicitly unpaired presentations of tone and periorbital stimulation (control, n = 16). Purkinje cell dendritic(More)
The nudibranch mollusk Hermissenda crassicornis' normal attraction to light can be suppressed by repeated pairings of light with rotation. The present study examines the effects of extinction procedures on this simple form of associative learning. Presentation of non-reinforced light steps following associative conditioning resulted in an attenuation of(More)