Article

Constrained principal component analysis reveals functionally connected load-dependent networks involved in multiple stages of working memory.

Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada.
Human Brain Mapping (Impact Factor: 6.88). 06/2011; 32(6):856-71. DOI: 10.1002/hbm.21072
Source: PubMed

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.

0 Bookmarks
 · 
72 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Optimally interpreting our situations and experiences frequently requires comparing the evidence supporting conflicting hypotheses and deciding which to accept. This decision is comparable to an "Aha!" moment reached during insightful problem solving. We used a probabilistic reasoning task to investigate the neural activity underlying these processes. Participants rated the probability that a given focal hypothesis, rather than its alternative, was true. Decisions to accept the focal hypothesis elicited a stronger signal than decisions to reject it in a network involving the dorsal anterior cingulate cortex (dACC) and functionally connected frontal, parietal, and occipital regions. Follow-up analyses suggested that this was not simply a higher overall level of activation within the dACC or other individual regions of the network, but reflected a stronger signal for the network as a whole. This result is discussed in terms of functional connectivity between the dACC and other brain regions as a possible mechanism for coherence between components of a mental representation.
    Neuropsychologia 03/2013; · 3.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose functional multiple-set canonical correlation analysis for exploring associations among multiple sets of functions. The proposed method includes functional canonical correlation analysis as a special case when only two sets of functions are considered. As in classical multiple-set canonical correlation analysis, computationally, the method solves a matrix eigen-analysis problem through the adoption of a basis expansion approach to approximating data and weight functions. We apply the proposed method to functional magnetic resonance imaging (fMRI) data to identify networks of neural activity that are commonly activated across subjects while carrying out a working memory task. Key wordsfunctional data–multiple-set canonical correlation analysis–functional canonical correlation analysis–functional magnetic resonance imaging data
    Psychometrika 04/2012; 77(1):48-64. · 2.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We evaluated sentence comprehension of variety of sentence constructions and components of short-term memory (STM) in 53 individuals with acute ischemic stroke, to test some current hypotheses about the role of Broca's area in these tasks. We found that some patients show structure-specific, task-independent deficits in sentence comprehension, with chance level of accuracy on passive reversible sentences, more impaired comprehension of object-cleft than subject-cleft sentences, and more impaired comprehension of reversible than irreversible sentences in both sentence-picture matching and enactment tasks. In a dichotomous analysis, this pattern of "asyntactic comprehension" was associated with dysfunctional tissue in left angular gyrus, rather than dysfunctional tissue in Broca's area as previously proposed. Tissue dysfunction in left Brodmann area (BA) 44, part of Broca's area, was associated with phonological STM impairment defined by forward digit span≤4. Verbal working memory (VWM) defined by backward digit span≤2 was associated with tissue dysfunction left premotor cortex (BA 6). In a continuous analysis, patients with acute ischemia in left BA 44 were impaired in phonological STM. Patients with ischemia in left BA 45 and BA 6 were impaired in passive, reversible sentences, STM, and VWM. Patients with ischemia in left BA 39 were impaired in passive reversible sentences, object-cleft sentences, STM, and VWM. Therefore, various components of working memory seem to depend on a network of brain regions that include left angular gyrus and posterior frontal cortex (BA 6, 44, 45); left BA 45 and angular gyrus (BA 39) may have additional roles in comprehension of syntax such as thematic role checking.
    Cortex 10/2011; 48(10):1288-97. · 6.16 Impact Factor

Full-text (3 Sources)

View
31 Downloads
Available from
May 21, 2014