Human brain mapping
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Human brain mapping · Feb 2009
Strengthening of laterality of verbal and visuospatial functions during childhood and adolescence.
Cognitive functions in the child's brain develop in the context of complex adaptive processes, determined by genetic and environmental factors. Little is known about the cerebral representation of cognitive functions during development. In particular, knowledge about the development of right hemispheric (RH) functions is scarce. ⋯ A positive correlation was found between Verbal-IQ and the LI during a language task (r = 0.585, P = 0.028), while visuospatial skills correlated with LIs of visual search (r = -0.621, P = 0.018). To summarize, cognitive development is accompanied by changes in the functional representation of neuronal circuitries, with a strengthening of lateralization not only for LH but also for RH functions. Our data show that age and performance, independently, account for the increases of laterality with age.
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Human brain mapping · Feb 2009
Sex differences in brain activation to anticipated and experienced pain in the medial prefrontal cortex.
Previous studies on sex differences in neural responses to noxious stimuli yielded mixed results. Both increased and decreased brain activation in several brain areas in women as compared to men has been reported. The current event-related functional magnetic resonance imaging study used a parametric design with different levels of the intensity of electrical stimulation in order to investigate sex differences in brain activation during pain processing. ⋯ Pronounced sex differences in brain activation were found in response to stimulation below the detection threshold and for the most intense pain stimuli in the medial prefrontal cortex (MPFC). Under both the conditions, women showed stronger activation in a region of the pregenual MPFC, which has been implicated in introspective, self-focused information processing. The results suggest that women, as compared to men, show increased self-related attention during anticipation of pain and in response to intense pain.
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Human brain mapping · Feb 2009
Functional connectivity of default mode network components: correlation, anticorrelation, and causality.
The default mode network (DMN), based in ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC), exhibits higher metabolic activity at rest than during performance of externally oriented cognitive tasks. Recent studies have suggested that competitive relationships between the DMN and various task-positive networks involved in task performance are intrinsically represented in the brain in the form of strong negative correlations (anticorrelations) between spontaneous fluctuations in these networks. Most neuroimaging studies characterize the DMN as a homogenous network, thus few have examined the differential contributions of DMN components to such competitive relationships. ⋯ Activity in vmPFC negatively predicted activity in parietal visual spatial and temporal attention networks, whereas activity in PCC negatively predicted activity in prefrontal-based motor control circuits. Granger causality analyses suggest that vmPFC and PCC exert greater influence on their anticorrelated networks than the other way around, suggesting that these two default mode nodes may directly modulate activity in task-positive networks. Thus, the two major nodes comprising the DMN are differentiated with respect to the specific brain systems with which they interact, suggesting greater heterogeneity within this network than is commonly appreciated.
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Human brain mapping · Feb 2009
Re-entrant projections modulate visual cortex in affective perception: evidence from Granger causality analysis.
Re-entrant modulation of visual cortex has been suggested as a critical process for enhancing perception of emotionally arousing visual stimuli. This study explores how the time information inherent in large-scale electrocortical measures can be used to examine the functional relationships among the structures involved in emotional perception. Granger causality analysis was conducted on steady-state visual evoked potentials elicited by emotionally arousing pictures flickering at a rate of 10 Hz. ⋯ Results demonstrated increased coupling between visual and cortical areas when viewing emotionally arousing content. Specifically, intraparietal to inferotemporal and precuneus to calcarine connections were stronger for emotionally arousing picture content. Thus, we provide evidence for re-entrant signal flow during emotional perception, which originates from higher tiers and enters lower tiers of visual cortex.