Multiple forms of non-associative plasticity in Aplysia: a behavioural, cellular and pharmacological analysis.

K. Fitzgerald, W. G. Wright, E. A. Marcus, T. J. Carew

Research output: Contribution to journalArticle

Abstract

A complete understanding of the cellular mechanisms underlying the formation of associations between stimuli, as occurs during classical conditioning, requires an understanding of the non-associative effects of the individual stimuli. The siphon withdrawal reflex of Aplysia exhibits both non-associative and associative learning when a tactile stimulus to the siphon serves as a conditioned stimulus, and tail shock serves as an unconditioned stimulus. In this chapter we describe experiments which examine the non-associative effects of tail shock at three different levels of analysis. At a behavioural level we found that the magnitude, and even the sign of reflex modulation induced by tail shock depended critically on three parameters: (i) the state of the reflex (habituated or non-habituated); (ii) the strength of the tail shock, and (iii) the time of testing after tail shock. Specifically, when non-habituated responses produced by water jet stimuli to the siphon were examined, tail shock produced transient inhibition 90 s later; facilitation of non-habituated responses (sensitization) only emerged after a considerable delay of 20-30 min. When habituated responses were examined, tail shock produced immediate facilitation (dishabituation); the amount of facilitation was inversely related to the strength of tail shock, with stronger shock producing no dishabituation. At a cellular level it was found that the complex excitatory postsynaptic potential (EPSP) in siphon motor neurons produced by water jet stimuli to the siphon provides a reliable cellular correlate of several of the non-associative effects of tail shock that we observe behaviourally. When non-decremented complex EPSPS were examined, strong tail shock produced transient inhibition at a test 90 s after shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish (US)
Pages (from-to)171-178
Number of pages8
JournalPhilosophical transactions of the Royal Society of London. Series B, Biological sciences
Volume329
Issue number1253
DOIs
StatePublished - Aug 29 1990

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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