Human brain mapping
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Human brain mapping · Oct 2011
Dynamic changes in functional cerebral connectivity of spatial cognition during the menstrual cycle.
Functional cerebral asymmetries (FCAs) in women have been shown to vary with changing levels of sex hormones during the menstrual cycle. Previous studies have suggested that interhemispheric interaction forms a key component in generating FCAs and it has been shown behaviorally and by functional imaging that interhemispheric interaction changes during the menstrual cycle, at least for a left hemisphere dominant task. ⋯ The behavioral data confirmed the right hemisphere advantage for the figure comparison task as well as changes of the right hemisphere advantage during the menstrual cycle. Imaging data showed cycle phase-related changes in lateralized brain activation within the task-dominant hemisphere and changes in connectivity between nonhomotopic areas of both hemispheres, suggesting that changes in functional brain organization in women during the menstrual cycle are not only restricted to hormone-related changes of interhemispheric inhibition between homotopic areas, as has been proposed earlier, but might additionally apply to changes of neuronal processes within the hemispheres which seem to be modulated by heterotopic functional connectivity between hemispheres.
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Human brain mapping · Oct 2011
Gray and white matter asymmetries in healthy individuals aged 21-29 years: a voxel-based morphometry and diffusion tensor imaging study.
The hemispheres of the human brain are functionally and structurally asymmetric. The study of structural asymmetries provides important clues to the neuroanatomical basis of lateralized brain functions. Previous studies have demonstrated age-related changes in morphology and diffusion properties of brain tissue. ⋯ Leftward volume asymmetry of the planum temporale and leftward FA asymmetry of the arcuate fasciculus were simultaneously demonstrated. Post hoc analysis showed that the gray matter volume of the planum temporale and FA of the arcuate fasciculus were positively related (Pearson correlation coefficient, 0.43; P < 0.0001). The results of our study demonstrate gray and white matter asymmetry in right-handed healthy young adults and suggest that leftward volume asymmetry of the planum temporale and leftward FA asymmetry of the arcuate fasciculus may be related.
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Human brain mapping · Oct 2011
The neural correlates of intertemporal decision-making: contributions of subjective value, stimulus type, and trait impulsivity.
Making choices between payoffs available at different points in time reliably engages a decision-making brain circuit that includes medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and ventral striatum (VS). Previous neuroimaging studies produced differing accounts of the functions of these regions, including that these regions: (1) are sensitive to the value of rewards discounted by a function of delay ('subjective value'); (2) are differentially sensitive to the availability of an immediate reward; and (3) are implicated in impulsive decision-making. In this event-related fMRI study of 20 volunteers, these hypotheses were investigated simultaneously using a delay discounting task in which magnitude of rewards and stimulus type, i.e., the presence or absence of an immediate option, were independently varied, and in which participants' trait impulsivity was assessed with the Barratt Impulsiveness Scale. ⋯ Moderation by individual differences in trait impulsivity was specific to the mPFC. Conjunction analysis showed significant overlap in mPFC and PCC for the main effects of subjective value and stimulus type, indicating these regions may serve multiple distinct roles during intertemporal decision-making. These findings significantly advance our understanding of the specificity and overlap of functions subserved by different regions involved in intertemporal decision-making, and help to reconcile conflicting accounts in the literature.
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Human brain mapping · Sep 2011
Right parietal brain activity precedes perceptual alternation during binocular rivalry.
We investigated perceptual reversals for intermittently presented stimuli during binocular rivalry and physical alternation while the ongoing EEG was recorded from 64 channels. EEG topographies immediately preceding stimulus-onset were analyzed and two topographies doubly dissociated perceptual reversals from non-reversals. The estimated intracranial generators associated with these topographies were stronger in right inferior parietal cortex and weaker bilaterally in the ventral stream before perceptual reversals. ⋯ For both types of multi-stable stimuli, the dorsal stream is more active preceding perceptual reversals. Activity in the ventral stream, however, differed for binocular rivalry compared to ambiguous figures. The results from the two studies suggest a causal role for the right inferior parietal cortex in generating perceptual reversals regardless of the type of multi-stable stimulus, while activity in the ventral stream appears to depend on the particular type of stimulus.
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Human brain mapping · Sep 2011
Regional gray matter density associated with emotional intelligence: evidence from voxel-based morphometry.
Emotional Intelligence (EI) is the ability to monitor one's own and others' emotions and the ability to use the gathered information to guide one's thinking and action. EI is thought to be important for social life making it a popular subject of research. However, despite the existence of previous functional imaging studies on EI, the relationship between regional gray matter morphology and EI has never been investigated. ⋯ We found significant negative relationships between the Intrapersonal factor and regional gray matter density (rGMD) (1-a) in an anatomical cluster that included the right anterior insula, (1-b) in the right cerebellum, (1-c) in an anatomical cluster that extends from the cuneus to the precuneus, (1-d) and in an anatomical cluster that extends from the medial prefrontal cortex to the left lateral fronto-polar cortex. We also found significant positive correlations between the Interpersonal factor and rGMD in the right superior temporal sulcus, and significant negative correlations between the Situation Management factor and rGMD in the ventromedial prefrontal cortex. These findings suggest that each factor of EI in healthy young people is related to the specific brain regions known to be involved in the networks of social cognition and self-related recognition, and in the somatic marker circuitry.