Time-varying effective connectivity during visual object naming as a function of semantic demands

Poch, Claudia, Garrido, Marta I, Igoa, Jose Manuel, Belinchon, Mercedes, Garcia-Morales, Irene and Campo, Pablo (2015) Time-varying effective connectivity during visual object naming as a function of semantic demands. Journal of Neuroscience, 35 23: 8768-8776. doi:10.1523/JNEUROSCI.4888-14.2015

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Author Poch, Claudia
Garrido, Marta I
Igoa, Jose Manuel
Belinchon, Mercedes
Garcia-Morales, Irene
Campo, Pablo
Title Time-varying effective connectivity during visual object naming as a function of semantic demands
Journal name Journal of Neuroscience   Check publisher's open access policy
ISSN 1529-2401
0270-6474
Publication date 2015-06-10
Year available 2015
Sub-type Article (original research)
DOI 10.1523/JNEUROSCI.4888-14.2015
Open Access Status File (Publisher version)
Volume 35
Issue 23
Start page 8768
End page 8776
Total pages 9
Place of publication Washington, United States
Publisher Society for Neuroscience
Collection year 2016
Language eng
Subject 2800 Neuroscience
Abstract Accumulating evidence suggests that visual object understanding involves a rapid feedforward sweep, after which subsequent recurrent interactions are necessary. The extent to which recurrence plays a critical role in object processing remains to be determined. Recent studies have demonstrated that recurrent processing is modulated by increasing semantic demands. Differentially from previous studies, we used dynamic causal modeling to model neural activity recorded with magnetoencephalography while 14 healthy humans named two sets of visual objects that differed in the degree of semantic accessing demands, operationalized in terms of the values of basic psycholinguistic variables associated with the presented objects (age of acquisition, frequency, and familiarity). This approach allowed us to estimate the directionality of the causal interactions among brain regions and their associated connectivity strengths. Furthermore, to understand the dynamic nature of connectivity (i.e., the chronnectome; Calhoun et al., 2014) we explored the time-dependent changes of effective connectivity during a period (200–400 ms) where adding semantic-feature information improves modeling and classifying visual objects, at 50 ms increments. First, we observed a graded involvement of backward connections, that became active beyond 200 ms. Second, we found that semantic demands caused a suppressive effect in the backward connection from inferior frontal cortex (IFC) to occipitotemporal cortex over time. These results complement those from previous studies underscoring the role of IFC as a common source of top-down modulation, which drives recurrent interactions with more posterior regions during visual object recognition. Crucially, our study revealed the inhibitory modulation of this interaction in situations that place greater demands on the conceptual system.
Keyword Dynamic causal modeling
Effective connectivity
Recurrent interactions
Top-down modulation
Visual object naming
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Brain Institute Publications
Official 2016 Collection
Centre for Advanced Imaging Publications
 
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