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Different circuit and monoamine mechanisms consolidate long-term memory in aversive and reward classical conditioning

journal contribution
posted on 2023-06-07, 20:11 authored by Ildiko KemenesIldiko Kemenes, Michael O'Shea, Paul R Benjamin
There has been considerable recent interest in comparing the circuit and monoamine-based mechanisms of aversive and reward-associative conditioning in a number of vertebrate and invertebrate model systems. The mollusc Lymnaea stagnalis provides a unique opportunity to explore changes in the neural and chemical pathways underlying these two different types of conditioning as its feeding circuitry has been thoroughly characterised. Animals can learn after a single trial to associate the same CS (amyl acetate) either with a punishment (quinine) or reward (sucrose), showing either a reduced or an elevated feeding response, respectively, to the CS. We previously showed that reward conditioning strengthened the direct excitatory pathway from the lips to the feeding central pattern generator in the buccal ganglia through the activation of feeding interneurons in the cerebral ganglia. Now we demonstrate that aversive conditioning enhances the strength of a different inhibitory pathway that suppresses feeding but has no effect on the excitatory pathway. Here we show that consolidation of long-term memory (LTM) in reward conditioning depends on dopamine but not octopamine. In contrast, aversive LTM depends on octopamine but not dopamine. Octopamine is the invertebrate equivalent of noradrenalin, so these results on the monoamine dependence of reward and aversive conditioning in Lymnaea resemble, at the transmitter receptor level, those in mammals but are the opposite of those in another invertebrate group, the insects.

History

Publication status

  • Published

Journal

European Journal of Neuroscience

ISSN

0953-816X

Publisher

Blackwell Publishing

Issue

1

Volume

33

Page range

143-152

Department affiliated with

  • Neuroscience Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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