Document Detail

Multiple systems of category learning.
MedLine Citation:
PMID:  17904637     Owner:  NLM     Status:  MEDLINE    
We review neuropsychological and neuroimaging evidence for the existence of three qualitatively different categorization systems. These categorization systems are themselves based on three distinct memory systems: working memory (WM), explicit long-term memory (explicit LTM), and implicit long-term memory (implicit LTM). We first contrast categorization based on WM with that based on explicit LTM, where the former typically involves applying rules to a test item and the latter involves determining the similarity between stored exemplars or prototypes and a test item. Neuroimaging studies show differences between brain activity in normal participants as a function of whether they are instructed to categorize novel test items by rule or by similarity to known category members. Rule instructions typically lead to more activation in frontal or parietal areas, associated with WM and selective attention, whereas similarity instructions may activate parietal areas associated with the integration of perceptual features. Studies with neurological patients in the same paradigms provide converging evidence, e.g., patients with Alzheimer's disease, who have damage in prefrontal regions, are more impaired with rule than similarity instructions. Our second contrast is between categorization based on explicit LTM with that based on implicit LTM. Neuropsychological studies with patients with medial-temporal lobe damage show that patients are impaired on tasks requiring explicit LTM, but perform relatively normally on an implicit categorization task. Neuroimaging studies provide converging evidence: whereas explicit categorization is mediated by activation in numerous frontal and parietal areas, implicit categorization is mediated by a deactivation in posterior cortex.
Edward E Smith; Murray Grossman
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Review     Date:  2007-08-15
Journal Detail:
Title:  Neuroscience and biobehavioral reviews     Volume:  32     ISSN:  0149-7634     ISO Abbreviation:  Neurosci Biobehav Rev     Publication Date:  2008  
Date Detail:
Created Date:  2008-01-29     Completed Date:  2008-05-02     Revised Date:  2014-09-09    
Medline Journal Info:
Nlm Unique ID:  7806090     Medline TA:  Neurosci Biobehav Rev     Country:  United States    
Other Details:
Languages:  eng     Pagination:  249-64     Citation Subset:  IM    
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MeSH Terms
Brain Mapping*
Cerebral Cortex / physiology*
Concept Formation*
Discrimination Learning / physiology*
Memory / physiology*
Grant Support
AG15116/AG/NIA NIH HHS; AG17586/AG/NIA NIH HHS; P01 AG017586/AG/NIA NIH HHS; P01 AG017586-070001/AG/NIA NIH HHS; R01 AG015116/AG/NIA NIH HHS; R01 AG015116-08/AG/NIA NIH HHS

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