Document Detail


Subcellular, cellular, and circuit mechanisms underlying classical conditioning in Hermissenda crassicornis.
MedLine Citation:
PMID:  16437555     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A breakthrough for studying the neuronal basis of learning emerged when invertebrates with simple nervous systems, such as the sea slug Hermissenda crassicornis, were shown to exhibit classical conditioning. Hermissenda learns to associate light with turbulence: prior to learning, naive animals move toward light (phototaxis) and contract their foot in response to turbulence; after learning, conditioned animals delay phototaxis in response to light. The photoreceptors of the eye, which receive monosynaptic inputs from statocyst hair cells, are both sensory neurons and the first site of sensory convergence. The memory of light associated with turbulence is stored as changes in intrinsic and synaptic currents in these photoreceptors. The subcellular mechanisms producing these changes include activation of protein kinase C and MAP kinase, which act as coincidence detectors because they are activated by convergent signaling pathways. Pathways of interneurons and motorneurons, where additional changes in excitability and synaptic connections are found, contribute to delayed phototaxis. Bursting activity recorded at several points suggest the existence of small networks that produce complex spatiotemporal firing patterns. Thus, the change in behavior may be produced by a nonlinear transformation of spatiotemporal firing patterns caused by plasticity of synaptic and intrinsic channels. The change in currents and the activation of PKC and MAPK produced by associative learning are similar to those observed in hippocampal and cerebellar neurons after rabbit classical conditioning, suggesting that these represent general mechanisms of memory storage. Thus, the knowledge gained from further study of Hermissenda will continue to illuminate mechanisms of mammalian learning.
Authors:
Kim T Blackwell
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.; Review    
Journal Detail:
Title:  Anatomical record. Part B, New anatomist     Volume:  289     ISSN:  1552-4906     ISO Abbreviation:  Anat Rec B New Anat     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2006-02-01     Completed Date:  2006-04-18     Revised Date:  2014-09-08    
Medline Journal Info:
Nlm Unique ID:  101234289     Medline TA:  Anat Rec B New Anat     Country:  United States    
Other Details:
Languages:  eng     Pagination:  25-37     Citation Subset:  IM    
Copyright Information:
(c) 2006 Wiley-Liss, Inc.
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MeSH Terms
Descriptor/Qualifier:
Animals
Association Learning / physiology*
Computer Simulation
Conditioning, Classical / physiology*
Hermissenda / physiology*
Humans
Ion Channels / physiology
Light
Memory
Neurons / physiology
Photoreceptor Cells / physiology
Signal Transduction*
Synapses
Grant Support
ID/Acronym/Agency:
K21 MH001141/MH/NIMH NIH HHS; K21 MH001141-05/MH/NIMH NIH HHS
Chemical
Reg. No./Substance:
0/Ion Channels
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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