title: Temporal sequence of hemispheric network activation during semantic processing: a functional network connectivity analysis.
abstract: To explore the temporal sequence of, and the relationship between, the left and right hemispheres (LH and RH) during semantic memory (SM) processing we identified the neural networks involved in the performance of functional MRI semantic object retrieval task (SORT) using group independent component analysis (ICA) in 47 healthy individuals. SORT requires participants to determine whether word pairs describing object features combine to retrieve an object. Functional network connectivity (FNC) was used to assess the correlations between components' time courses. Results showed that semantic left and right hemisphere networks comprise two independent ICA components. The components' time courses were highly correlated and RH activation preceded that of the LH. Moreover, this correlation was significantly stronger in better vs. poorer performers of the SORT. These results indicate an early activation of the RH that is closely followed by activation of the LH, to facilitate performance during word retrieval from SM.
authors.affiliation: Olin Neuropsychiatry Research Center, Institute of Living, Hartford Hospital, Hartford, CT, United States. massaf@harthosp.org
authors.forename: Michal
authors.initials: M
authors.lastname: Assaf
authors.forename: Kanchana
authors.initials: K
authors.lastname: Jagannathan
authors.forename: Vince
authors.initials: V
authors.lastname: Calhoun
authors.forename: Michael
authors.initials: M
authors.lastname: Kraut
authors.forename: John
authors.initials: J
authors.lastname: Hart
authors.forename: Godfrey
authors.initials: G
authors.lastname: Pearlson
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D011930:Reaction Time; D012660:Semantics; D013995:Time; D055815:Young Adult