title: Constrained principal component analysis reveals functionally connected load-dependent networks involved in multiple stages of working memory.
abstract: Constrained principal component analysis (CPCA) with a finite impulse response (FIR) basis set was used to reveal functionally connected networks and their temporal progression over a multistage verbal working memory trial in which memory load was varied. Four components were extracted, and all showed statistically significant sensitivity to the memory load manipulation. Additionally, two of the four components sustained this peak activity, both for approximately 3 s (Components 1 and 4). The functional networks that showed sustained activity were characterized by increased activations in the dorsal anterior cingulate cortex, right dorsolateral prefrontal cortex, and left supramarginal gyrus, and decreased activations in the primary auditory cortex and "default network" regions. The functional networks that did not show sustained activity were instead dominated by increased activation in occipital cortex, dorsal anterior cingulate cortex, sensori-motor cortical regions, and superior parietal cortex. The response shapes suggest that although all four components appear to be invoked at encoding, the two sustained-peak components are likely to be additionally involved in the delay period. Our investigation provides a unique view of the contributions made by a network of brain regions over the course of a multiple-stage working memory trial.
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Metzak
authors.forename: Eva
authors.initials: E
authors.lastname: Feredoes
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takane
authors.forename: Liang
authors.initials: L
authors.lastname: Wang
authors.forename: Sara
authors.initials: S
authors.lastname: Weinstein
authors.forename: Tara
authors.initials: T
authors.lastname: Cairo
authors.forename: Elton T C
authors.initials: ET
authors.lastname: Ngan
authors.forename: Todd S
authors.initials: TS
authors.lastname: Woodward
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D025341:Principal Component Analysis; D055815:Young Adult