Shifts of effective connectivity within a language network during rhyming and spelling

Tali Bitan*, James R. Booth, Janet Choy, Douglas D. Burman, Darren R. Gitelman, M. Marsel Mesulam

*Corresponding author for this work

Research output: Contribution to journalArticle

135 Scopus citations

Abstract

We used functional magnetic resonance imaging to examine task-specific modulations of effective connectivity within a left-hemisphere language network during spelling and rhyming judgments on visually presented words. We identified sites showing task-specific activations for rhyming in the lateral temporal cortex (LTC) and for spelling in the intraparietal sulcus (IPS). The inferior frontal gyrus (IFG) and fusiform gyrus were engaged by both tasks. Dynamic causal modeling showed that each task preferentially strengthened modulatory influences converging on its task-specific site (LTC for rhyming, IPS for spelling). These remarkably selective and symmetrical findings demonstrate that the nature of the behavioral task dynamically shifts the locus of integration (or convergence) to the network component specialized for that task. Furthermore, they suggest that the role of the task-selective areas is to provide a differential synthesis of incoming information rather than providing differential control signals influencing the activity of other network components. Our findings also showed that switching tasks led to changes in the target area influenced by the IFG, suggesting that the IFG may play a pivotal role in setting the cognitive context for each task. We propose that task-dependent shifts in effective connectivity are likely to be mediated through top-down modulations from the IFG to the task-selective regions in a way that differentially enhances their sensitivity to incoming word-form information.

Original languageEnglish (US)
Pages (from-to)5397-5403
Number of pages7
JournalJournal of Neuroscience
Volume25
Issue number22
DOIs
StatePublished - Jun 1 2005

Keywords

  • Convergence zones
  • Dynamic causal modeling
  • Fusiform gyrus
  • Inferior frontal gyrus
  • Reading
  • fMRI

ASJC Scopus subject areas

  • Neuroscience(all)

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