Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 5 (7), 433-41

Investigation of Information Flow During a Novel Working Memory Task in Individuals With Traumatic Brain Injury

Affiliations

Investigation of Information Flow During a Novel Working Memory Task in Individuals With Traumatic Brain Injury

Ekaterina Dobryakova et al. Brain Connect.

Abstract

Working memory (WM) is often compromised after traumatic brain injury (TBI). A number of functional and effective connectivity studies investigated the interaction between brain regions during WM task performance. However, previously used WM tasks did not allow differentiation of WM subprocesses such as capacity and manipulation. We used a novel WM paradigm, CapMan, to investigate effective connectivity associated with the capacity and manipulation subprocesses of WM in individuals with TBI relative to healthy controls (HCs). CapMan allows independent investigation of brain regions associated with capacity and manipulation, while minimizing the influence of other WM-related subprocesses. Areas of the fronto-parietal WM network, previously identified in healthy individuals as engaged in capacity and manipulation during CapMan, were analyzed with the Independent Multiple-sample Greedy Equivalence Search (IMaGES) method to investigate the differences in information flow between healthy individuals and individuals with TBI. We predicted that diffuse axonal injury that often occurs after TBI might lead to changes in task-based effective connectivity and result in hyperconnectivity between the regions engaged in task performance. In accordance with this hypothesis, TBI participants showed greater inter-hemispheric connectivity and less coherent information flow from posterior to anterior brain regions compared with HC participants. Thus, this study provides much needed evidence about the potential mechanism of neurocognitive impairments in individuals affected by TBI.

Keywords: TBI; attention; capacity; effective connectivity; fMRI; fronto-parietal network; manipulation; working memory.

Figures

<b>FIG. 1.</b>
FIG. 1.
(a) Matrix of CapMan conditions depicting information presented during the Start and Change cues. During the high manipulation condition, the probability of having to update the information in WM was 90%. During the low manipulation condition, this probability was 10%. Similarly, during the high capacity condition, the probability of having to retain three features was 90%; whereas during the low capacity condition, this probability was 10%. (b) An example of the two conditions analyzed here: high capacity, low manipulation condition (Cap-man), and low capacity, high manipulation (cap-Man). For the Cap-man trial, the Start cue indicates that a match would consist of a red, upper-case target letter, to the left side of the fixation. The Change cue indicates that the side and case features remain unaltered. The stimulus shown would be mismatch, since the letter appears in red and not in blue as directed by the change cue. Color images available online at www.liebertpub.com/brain
<b>FIG. 2.</b>
FIG. 2.
Effective connectivity graphs representing information flow during high capacity condition for HC and TBI groups. ACC, anterior cingulate cortex; HC, healthy control; IPL, inferior parietal lobule; ITG, inferior temporal gyrus; SMA, supplementary motor area; TBI, traumatic brain injury; VMPFC, ventromedial prefrontal cortex.
<b>FIG. 3.</b>
FIG. 3.
Effective connectivity graphs representing information flow during high manipulation condition for HC and TBI groups. DLPFC, dorsolateral prefrontal cortex.

Similar articles

See all similar articles

Cited by 5 articles

Publication types

LinkOut - more resources

Feedback