Neurophysiological alterations during strategy-based verbal learning in traumatic brain injury

Gary E. Strangman, Richard Goldstein, Therese M. O'Neil-Pirozzi, Kalika Kelkar, Christina Supelana, David Burke, Douglas I. Katz, Scott L. Rauch, Cary R. Savage, Mel B. Glenn

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Background: Verbal learning and strategic processing deficits are common sequelae of traumatic brain injury (TBI); however, the neurophysiological mechanisms underlying such deficits remain poorly understood. Methods. We performed functional magnetic resonance imaging (fMRI) in 25 individuals with chronic TBI (>1 year after injury) and 20 matched healthy controls. Subjects were scanned while encoding word lists, with free recall and recognition assessed after each scanning run. To vary the strategic processing load, participants learned semantically unrelated words (Unrelated condition), semantically related words under null instruction conditions (Spontaneous condition), and semantically related words following training on the use of a semantic clustering strategy (Directed condition). Results: Behavioral performance on recall, recognition, and semantic clustering improved significantly as follows: Unrelated < Spontaneous < Directed. Individuals with TBI exhibited impaired yet parallel behavioral performance relative to control participants. The fMRI measures of brain activity during verbal encoding revealed decreased activity in participants with TBI relative to controls in left dorsolateral prefrontal cortex (DLPFC; BA 9) and in a region spanning the left angular and supramarginal gyri (BA 39/40). Functional connectivity analysis revealed evidence of a functional-but not anatomical-breakdown in the connectivity between the DLPFC and other regions specifically when participants with TBI were directed to use the semantic encoding strategy. Conclusion. After TBI, the DLPFC appears to be decoupled from other active brain regions specifically when strategic control is required. We hypothesize that approaches designed to help re-couple DLPFC under such conditions may aid TBI cognitive rehabilitation.

Original languageEnglish (US)
Pages (from-to)226-236
Number of pages11
JournalNeurorehabilitation and Neural Repair
Volume23
Issue number3
DOIs
StatePublished - Mar 2009

Keywords

  • Behavioral neurology
  • Brain trauma
  • Cognitive rehabilitation
  • Functional neuroimaging
  • Semantic clustering

ASJC Scopus subject areas

  • Rehabilitation
  • Neurology
  • Clinical Neurology

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    Strangman, G. E., Goldstein, R., O'Neil-Pirozzi, T. M., Kelkar, K., Supelana, C., Burke, D., Katz, D. I., Rauch, S. L., Savage, C. R., & Glenn, M. B. (2009). Neurophysiological alterations during strategy-based verbal learning in traumatic brain injury. Neurorehabilitation and Neural Repair, 23(3), 226-236. https://doi.org/10.1177/1545968308324225