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Objective: A growing body of scientific evidence suggests that meditation may slow brain aging. The amygdala-a heterogenous brain region known to decrease in volume with increasing age-seems to be involved in meditation and affected by meditation. Thus, we hypothesized that the age-related decline of the amygdala is diminished in meditation practitioners., Methods: We investigated whether correlations between age and gray matter volumes of the amygdala are significantly reduced in 50 long-term meditators compared with 50 sex- and age-matched healthy controls. Both the meditator and control groups included 44% women. The age of the participants ranged between 24 and 77 years, with mean (standard deviation) ages of 50.4 (±11.8) years in meditators and 51.4 (±12.8) years in controls. In addition to studying the amygdala as a whole, we investigated its centromedial, laterobasal, and superficial subregions using a well-validated approach combining imaging-based signal intensities and cytoarchitectonically defined probabilities., Results: We detected significant group-by-age interactions for the whole amygdala and for its subregions. Follow-up analyses indicated negative age-related correlations in both meditators and controls (the older the participants, the smaller the volumes) but with significantly steeper aging trajectories in controls., Conclusions: Altogether, these findings suggest that the age-related volume loss of the amygdala is less pronounced in long-term meditators. This effect was particularly evident for the laterobasal subregion, which has been functionally linked to aspects of self-focused reflection., (Copyright © 2021 by the American Psychosomatic Society.)

We applied a new method to visualize the three-dimensional profile of sex differences in brain structure based on MRI scans of 100 young adults. We compared 50 men with 50 women, matched for age and other relevant demographics. As predicted, left hemisphere auditory and language-related regions were proportionally expanded in women versus men, suggesting a possible structural basis for the widely replicated sex differences in language processing. In men, primary visual, and visuo-spatial association areas of the parietal lobes were proportionally expanded, in line with prior reports of relative strengths in visuo-spatial processing in men. We relate these three-dimensional patterns to prior functional and structural studies, and to theoretical predictions based on nonlinear scaling of brain morphometry.

We used diffusion tensor imaging to investigate fractional anisotropy (FA), a measure of fiber tract integrity, in attention-deficit hyperactivity disorder (ADHD). Using a tract-based atlasing approach on six-direction diffusion tensor imaging data, we examined FA within the cingulum, corpus callosum, corticospinal tract, fornix, optic radiations, superior longitudinal fasciculus, uncinate fasciculus, and the superior and inferior occipitofrontal fasciculi in an all-male sample of 17 children and adolescents with ADHD and 16 age-matched controls. ADHD patients had significantly lower FA in the corticospinal tract (P=0.02) and the superior longitudinal fasciculus (P=0.017) compared with controls. Results support that disruptions in motor and attentional networks may contribute toward ADHD pathophysiology. Future research may clarify how ADHD subtype and psychiatric comorbidities affect diffusion measures.

Sex, handedness, and disease processes in schizophrenia may affect the magnitude and/or direction of structural brain asymmetries. Using MRI data from 67 healthy (30 men, 10 nondextral) and 84 schizophrenia patients (60 men, 16 nondextral), cortical thickness asymmetries were compared at high spatial resolution. Within-group asymmetries were observed in sensorimotor, perisylvian, and parahippocampal cortices (leftward) and in anterior mesial frontal cortices (rightward). Asymmetry patterns were similar across diagnosis and sex, although some regional asymmetry increases were observed in men. Hand preference (dextrality) significantly influenced regional asymmetries in parietal association and dorsomedial frontal cortices (false discovery rate-corrected), where medial-frontal regions showed diagnosis by dextrality effects (uncorrected). Thus, dextrality relates to cortical thickness asymmetries, although schizophrenia may differentially affect asymmetry patterns across handedness.

We applied novel mesh-based geometrical modeling methods to calculate and compare the thickness of the corpus callosum at high spatial resolution and to create profiles of average callosal shape in a well-matched sample (n=24) of individuals with Williams syndrome and controls. In close agreement with previous observations, superimposed surface maps indicate that the corpus callosum in Williams syndrome individuals is shorter and less curved. Moreover, we observed significantly thinner callosal regions in Williams syndrome individuals across the posterior surface, where group effects were less pronounced and spatially restricted in brain-size-adjusted data compared with native data. Circumscribed structural alterations in callosal morphology might be candidate anatomic substrates for the unique cognitive and behavioral profile associated with Williams syndrome.

Some empirical data suggest that sexual dimorphisms in callosal morphology exist, but findings are not consistently replicated across laboratories. We applied novel computational surface-based methods to encode callosal thickness at high spatial resolution. We further examined whether callosal thickness and related gender effects are influenced by brain size adjustments achieved through data scaling. Significant gender differences were absent in scaled data, and women showed no regional thickness increases compared with men (in either scaled or unscaled data). In unscaled data, men exhibited significantly greater callosal thickness in a number of regions that may be attributable to larger brain dimensions in men. Alternatively, given their regional specificity, the observed differences in unscaled callosal thickness may contribute to gender-specific cognition and behavior.