Reinforcement in an in vitro analog of appetitive classical conditioning of feeding behavior in Aplysia: blockade by a dopamine antagonist.

Fredy D Reyes, Riccardo Mozzachiodi, Douglas A Baxter, John H Byrne

W.M. Keck Center for Neurobiology of Learning and Memory, Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas 77030, USA.

Learning & memory (Cold Spring Harbor, N.Y.) 2005 May-Jun

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In a recently developed in vitro analog of appetitive classical conditioning of feeding in Aplysia, the unconditioned stimulus (US) was electrical stimulation of the esophageal nerve (En). This nerve is rich in dopamine (DA)-containing processes, which suggests that DA mediates reinforcement during appetitive conditioning. To test this possibility, methylergonovine was used to antagonize DA receptors. Methylergonovine (1 nM) blocked the pairing-specific increase in fictive feeding that is usually induced by in vitro classical conditioning. The present results and previous observation that methylergonovine also blocks the effects of contingent reinforcement in an in vitro analog of appetitive operant conditioning suggest that DA mediates reinforcement for appetitive associative conditioning of feeding in Aplysia.

Citation

Fredy D Reyes, Riccardo Mozzachiodi, Douglas A Baxter, John H Byrne. Reinforcement in an in vitro analog of appetitive classical conditioning of feeding behavior in Aplysia: blockade by a dopamine antagonist. Learning & memory (Cold Spring Harbor, N.Y.). 2005 May-Jun;12(3):216-20