title: The neural basis for novel semantic categorization.
abstract: We monitored regional cerebral activity with BOLD fMRI during acquisition of a novel semantic category and subsequent categorization of test stimuli by a rule-based strategy or a similarity-based strategy. We observed different patterns of activation in direct comparisons of rule- and similarity-based categorization. During rule-based category acquisition, subjects recruited anterior cingulate, thalamic, and parietal regions to support selective attention to perceptual features, and left inferior frontal cortex to helps maintain rules in working memory. Subsequent rule-based categorization revealed anterior cingulate and parietal activation while judging stimuli whose conformity with the rules was readily apparent, and left inferior frontal recruitment during judgments of stimuli whose conformity was less apparent. By comparison, similarity-based category acquisition showed recruitment of anterior prefrontal and posterior cingulate regions, presumably to support successful retrieval of previously encountered exemplars from long-term memory, and bilateral temporal-parietal activation for perceptual feature integration. Subsequent similarity-based categorization revealed temporal-parietal, posterior cingulate, and anterior prefrontal activation. These findings suggest that large-scale networks support relatively distinct categorization processes during the acquisition and judgment of semantic category knowledge.
authors.affiliation: Department of Neurology, University of Pennsylvania 19104-4283, USA. plkoenig@mail.med.upenn.edu
authors.forename: Phyllis
authors.initials: P
authors.lastname: Koenig
authors.forename: Edward E
authors.initials: EE
authors.lastname: Smith
authors.forename: Guila
authors.initials: G
authors.lastname: Glosser
authors.forename: Chris
authors.initials: C
authors.lastname: DeVita
authors.forename: Peachie
authors.initials: P
authors.lastname: Moore
authors.forename: Corey
authors.initials: C
authors.lastname: McMillan
authors.forename: Jim
authors.initials: J
authors.lastname: Gee
authors.forename: Murray
authors.initials: M
authors.lastname: Grossman
mesh_terms: D000328:Adult; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D004522:Educational Status; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D008959:Models, Neurological; D015203:Reproducibility of Results; D012660:Semantics