title: Classical conditioning analog enhanced acetylcholine responses but reduced excitability of an identified neuron.
abstract: Although classical and operant conditioning are operationally distinct, it is unclear whether these two forms of learning are mechanistically distinct or similar. Feeding behavior of Aplysia provides a useful model system for addressing this issue. Both classical and operant appetitive behavioral training enhance feeding, and neuronal correlates have been identified. Behavioral training was replicated by in vitro analogs that use isolated ganglia. Moreover, a single-cell analog of operant conditioning was developed using neuron B51, a cell important for the expression of the conditioned behavior. Here, a single-cell analog of classical conditioning was developed. Acetylcholine (ACh) mediated the conditioned stimulus (CS)-elicited excitation of B51 in ganglia and mimicked the CS in the single-cell analog of classical conditioning. Pairing ACh with dopamine, which mediates the unconditioned stimulus in ganglia, decreased the excitability of B51, and increased the CS-elicited excitation of B51, similar to results following both in vivo and in vitro classical training. Finally, a D1 dopamine receptor (D1R) agonist failed to support classical conditioning in the cellular analog, whereas D1R mediates reinforcement in operant conditioning.
authors: Department of Neurobiology and Anatomy, W.M. Keck Center for Neurobiology of Learning and Memory, The University of Texas Medical School at Houston, Houston, Texas 77030, USA.
authors: Fred D
authors: FD
authors: Lorenzetti
authors: Douglas A
authors: DA
authors: Baxter
authors: John H
authors: JH
authors: Byrne
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001048:Aplysia; D001522:Behavior, Animal / Q000187:drug effects; D001703:Biophysics; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003214:Conditioning, Classical / Q000187:drug effects*; D004298:Dopamine / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D017952:Ganglia, Invertebrate / Q000166:cytology; D018738:Hexamethonium / Q000494:pharmacology; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects; D007478:Iontophoresis / Q000379:methods; D009474:Neurons / Q000187:drug effects*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D018679:Cholinergic Agonists; D018733:Nicotinic Antagonists; D018738:Hexamethonium; D000109:Acetylcholine; D004298:Dopamine