Acquisition and retention of long-term habituation in Aplysia: correlation of behavioral and cellular processes.
To examine the cellular mechanisms responsible for transition from a short-term to a long-term behavioral modification, a rapid training procedure was developed for producing long-term habituation of the defensive withdrawal of gill and siphon in Aplysia. Four ten-trial training sessions, with 1(1/2)-hour intersession intervals, produced habituation that was retained for more than 1 week. This 5-hour procedure could be applied to a test system in the isolated abdominal ganglion where the cellular changes accompanying the acquisition of long-term habituation can be examined. During acquisition, intracellular recordings were obtained from L7, a major gill and siphon motor neuron, and the pattern of stimulation used in the behavioral experiments was applied to an afferent nerve. Acquisition was associated with a progressive decrease in the complex excitatory synaptic potential produced in L7 by afferent nerve stimulation. When retention was tested 24 hours later, the synaptic decrement was still evident. Thus, a behaviorally meaningful stimulus sequence, consisting of only 40 patterned stimuli, leads to changes in synaptic effectiveness lasting one or more days in a neural pathway involved in short-term habituation of this reflex.
D000200:Action Potentials; D000818:Animals; D005724:Ganglia / Q000502:physiology; D006185:Habituation, Psychophysiologic; D008465:Mechanoreceptors / Q000502:physiology; D008974:Mollusca; D009046:Motor Neurons / Q000502:physiology; D013216:Reflex, Startle; D013569:Synapses / Q000502:physiology; D013997:Time Factors