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L 9 modulation of gill withdrawal reflex habituation in Aplysia

1979; Wiley; Volume: 10; Issue: 3 Linguagem: Inglês

10.1002/neu.480100306

1097-4695

Ken Lukowiak,

Crustacean biology and ecology

Abstract Repeated tactile stimulation of the siphon in Aplysia normally results in habituation of the gill withdrawal reflex and a concomitant decrease in the amplitude of the excitatory synaptic input to gill motor neurons in the abdominal ganglion. It was found, however, that induced low‐level tonic activity in motor neuron L 9 , which does not itself elicit a gill withdrawal movement, prevented habituation of the reflex from occurring. Further, in preparations already habituated, this tonic low‐level activity brought about a reversal of habituation. Although tonic L 9 activity prevented the occurrence of habituation or brought about its reversal, it did not interfere with the synaptic decremental process which normally accompanies gill reflex habituation. Motor neurons L 7 and LDG 1 were found not to possess this ability of L 9 to modulate gill reflex habituation. Evidence suggests that L 9 's modulatory effect is mediated in the periphery, in the gill and not centrally in the abdominal ganglion.