A quantal analysis of the synaptic depression underlying habituation of the gill-withdrawal reflex in Aplysia.
Habituation, one of the simplest behavioral paradigms for studying memory, has recently been examined on the cellular level in the gill-withdrawal reflex in the mollusc Aplysia and in the escape response in cray-fish. In both cases short-term habituation involved a decrease in excitatory synaptic transmission at the synapses between the sensory neurons and their central target cells. To analyze the mechanisms of the synaptic depression in Aplysia, we applied a quantal analysis to synaptic transmission between the sensory and motor neurons of the gill-withdrawal reflex. Our results indicate that short-term habituation results from a presynaptic mechanism: a decrease in the number of transmitter quanta released per impulse. The sensitivity of the postsynaptic receptor remains unaltered.
D000200:Action Potentials; D000818:Animals; D003400:Astacoidea; D004924:Escape Reaction; D005724:Ganglia / Q000502:physiology; D005880:Gills / Q000502:physiology; D006185:Habituation, Psychophysiologic; D008974:Mollusca; D012018:Reflex; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission