title: Extensive individual differences in brain activations associated with episodic retrieval are reliable over time.
abstract: The localization of brain functions using neuroimaging techniques is commonly dependent on statistical analyses of groups of subjects in order to identify sites of activation, particularly in studies of episodic memory. Exclusive reliance on group analysis may be to the detriment of understanding the true underlying cognitive nature of brain activations. In the present study, we found that the patterns of brain activity associated with episodic retrieval are very distinct for individual subjects from the patterns of brain activity at the group level. These differences go beyond the relatively small variations due to cyctoarchitectonic differences or spatial normalization. We quantify this individual variability by cross-correlating volumes of brain images. We demonstrate that individual patterns of brain activity are reliable over time despite their extensive variability. We suggest that varied but reliable individual patterns of significant brain activity may be indicative of different cognitive strategies used to produce a recognition response. We believe that individual analysis in conjunction with group analysis may be critical to fully understanding the relationship between retrieval processes and underlying brain regions.
authors.affiliation: Department of Psychology, University of California, Santa Barbara 93106, USA. michael.miller@dartmouth.edu
authors.forename: Michael B
authors.initials: MB
authors.lastname: Miller
authors.forename: John Darrell
authors.initials: JD
authors.lastname: Van Horn
authors.forename: George L
authors.initials: GL
authors.lastname: Wolford
authors.forename: Todd C
authors.initials: TC
authors.lastname: Handy
authors.forename: Monica
authors.initials: M
authors.lastname: Valsangkar-Smyth
authors.forename: Souheil
authors.initials: S
authors.lastname: Inati
authors.forename: Scott
authors.initials: S
authors.lastname: Grafton
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gazzaniga
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D007206:Individuality; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D021641:Recognition, Psychology / Q000502:physiology; D015203:Reproducibility of Results