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Cross-hemispheric collaboration and segregation associated with task difficulty as revealed by structural and functional connectivity.
Abstract
Although it is known that brain regions in one hemisphere may interact very closely
with their corresponding contralateral regions (collaboration) or operate relatively
independent of them (segregation), the specific brain regions (where) and conditions
(how) associated with collaboration or segregation are largely unknown. We investigated
these issues using a split field-matching task in which participants matched the meaning
of words or the visual features of faces presented to the same (unilateral) or to
different (bilateral) visual fields. Matching difficulty was manipulated by varying
the semantic similarity of words or the visual similarity of faces. We assessed the
white matter using the fractional anisotropy (FA) measure provided by diffusion tensor
imaging (DTI) and cross-hemispheric communication in terms of fMRI-based connectivity
between homotopic pairs of cortical regions. For both perceptual and semantic matching,
bilateral trials became faster than unilateral trials as difficulty increased (bilateral
processing advantage, BPA). The study yielded three novel findings. First, whereas
FA in anterior corpus callosum (genu) correlated with word-matching BPA, FA in posterior
corpus callosum (splenium-occipital) correlated with face-matching BPA. Second, as
matching difficulty intensified, cross-hemispheric functional connectivity (CFC) increased
in domain-general frontopolar cortex (for both word and face matching) but decreased
in domain-specific ventral temporal lobe regions (temporal pole for word matching
and fusiform gyrus for face matching). Last, a mediation analysis linking DTI and
fMRI data showed that CFC mediated the effect of callosal FA on BPA. These findings
clarify the mechanisms by which the hemispheres interact to perform complex cognitive
tasks.
Type
Journal articleSubject
connectivitydiffusion
face processing
interhemispheric
semantic memory
white matter
Brain Mapping
Cerebrum
Corpus Callosum
Diffusion Tensor Imaging
Female
Functional Laterality
Humans
Magnetic Resonance Imaging
Male
Neural Pathways
Photic Stimulation
Psychomotor Performance
Reaction Time
Young Adult
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https://hdl.handle.net/10161/10282Published Version (Please cite this version)
10.1523/JNEUROSCI.0464-15.2015Publication Info
Davis, Simon W; & Cabeza, Roberto (2015). Cross-hemispheric collaboration and segregation associated with task difficulty as
revealed by structural and functional connectivity. J Neurosci, 35(21). pp. 8191-8200. 10.1523/JNEUROSCI.0464-15.2015. Retrieved from https://hdl.handle.net/10161/10282.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Roberto Cabeza
Professor of Psychology and Neuroscience
My laboratory investigates the neural correlates of memory and cognition in young
and older adults using fMRI. We have three main lines of research: First, we distinguish
the neural correlates of various episodic memory processes. For example, we have compared
encoding vs. retrieval, item vs. source memory, recall vs. recognition, true vs. false
memory, and emotional vs. nonemotional memory. We are particularly interested in the
contribution of prefrontal cortex (PFC) and medial temporal lobe (M
Simon Wilton Davis
Assistant Professor in Neurology
My research centers around the use of structural and functional imaging measures to
study the shifts in network architecture in the aging brain. I am specifically interested
in changes in how changes in structural and functional connectivity associated with
aging impact the semantic retrieval of word or fact knowledge. Currently this involves
asking why older adults have particular difficulty in certain kinds of semantic retrieval,
despite the fact that vocabularies and knowledge stores typic
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