title: Language networks associated with computerized semantic indices.
abstract: Tests of generative semantic verbal fluency are widely used to study organization and representation of concepts in the human brain. Previous studies demonstrated that clustering and switching behavior during verbal fluency tasks is supported by multiple brain mechanisms associated with semantic memory and executive control. Previous work relied on manual assessments of semantic relatedness between words and grouping of words into semantic clusters. We investigated a computational linguistic approach to measuring the strength of semantic relatedness between words based on latent semantic analysis of word co-occurrences in a subset of a large online encyclopedia. We computed semantic clustering indices and compared them to brain network connectivity measures obtained with task-free fMRI in a sample consisting of healthy participants and those differentially affected by cognitive impairment. We found that semantic clustering indices were associated with brain network connectivity in distinct areas including fronto-temporal, fronto-parietal and fusiform gyrus regions. This study shows that computerized semantic indices complement traditional assessments of verbal fluency to provide a more complete account of the relationship between brain and verbal behavior involved organization and retrieval of lexical information from memory.
authors.affiliation: University of Minnesota Center for Clinical and Cognitive Neuropharmacology, Minneapolis, MN, USA. Electronic address: pakh0002@umn.edu.
authors.forename: Serguei V S
authors.initials: SV
authors.lastname: Pakhomov
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, USA; Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Jones
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Knopman
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology; D003071:Cognition / Q000502:physiology; D003198:Computer Simulation; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D012660:Semantics; D014705:Verbal Behavior / Q000502:physiology
keywords: Generative verbal fluency; Latent semantic analysis; Semantic clustering; Semantic memory; Semantics; Task-free fMRI