Shifts of Effective Connectivity within a Language Network during Rhyming and Spelling
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Issue Date
2005-06-01Author
Bitan, Tali
Booth, James R.
Choy, Janet
Burman, Douglas D.
Gitelman, Darren R.
Mesulam, M. Marsel
Publisher
Society for Neuroscience
Type
Article
Article Version
Scholarly/refereed, publisher version
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Show full item recordAbstract
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.
Description
This is the published version, also available here: http://dx.doi.org/10.1523/JNEUROSCI.0864-05.2005.
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Citation
Bitan, Tali., Booth, James R., Choy, Janet., Burman, Douglas D., Gitelman, Darren R., Mesulam, M. Marsel. "Shifts of Effective Connectivity within a Language Network during Rhyming and Spelling." The Journal of Neuroscience, 1 June 2005, 25(22): 5397-5403; http://dx.doi.org/10.1523/JNEUROSCI.0864-05.2005.
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