Structural asymmetry varies across individuals, brain regions, and metrics of cortical organization. The current study investigated regional differences in asymmetry of cortical surface area, thickness, and local gyrification, and the extent of between-subject variability in these metrics, in a sample of healthy young adults (N = 200). Between-subject variability in cortical structure may provide a means to assess the extent of biological flexibility or constraint of brain regions, and we explored the potential influence of this variability on the phenotypic expression of structural asymmetry. The findings demonstrate that structural asymmetries are nearly ubiquitous across the cortex, with differing regional organization for the three cortical metrics. This implies that there are multiple, only partially overlapping, maps of structural asymmetry. The results further indicate that the degree of asymmetry of a brain region can be predicted by the extent of the region’s between-subject variability. These findings provide evidence that reduced biological constraint promotes the expression of strong structural asymmetry.

Bilingualism represents an interesting model of possible experience-dependent alterations in brain structure. The current study examines whether interhemispheric adaptations in brain structure are associated with bilingualism. Corpus callosum volume and cortical thickness asymmetry across 13 regions of interest (selected to include critical language and bilingual cognitive control areas) were measured in a sample of Spanish-English bilinguals and age- and gender-matched monolingual individuals (N = 39 per group). Cortical thickness asymmetry of the anterior cingulate region differed across groups, with thicker right than left cortex for bilinguals and the reverse for monolinguals. In addition, two adjacent regions of the corpus callosum (mid-anterior and central) had greater volume in bilinguals. The findings suggest that structural indices of interhemispheric organization in a critical cognitive control region are sensitive to variations in language experience.

Various cognitive differences have been reported between consistent and weak handers (Prichard, Propper, & Christman, 2013), but little is known about the neurobiological factors that may be associated with this distinction. The current study examined cortical structural lateralization and corpus callosum volume in a large, well-matched sample of young adults (N = 164) to explore potential neurostructural bases for this hand group difference. The groups did not differ in corpus callosum volume. However, at the global hemispheric level, weak handers had reduced or absent asymmetries for gray and white matter volume, cortical surface area, thickness, and local gyrification, relative to consistent handers. Group differences were also observed for some regional hemispheric asymmetries, the most prominent of which was reduced or absent gyrification asymmetry for weak handers in a large region surrounding the central sulcus and extending into parietal association cortex. The findings imply that variations in handedness strength are associated with differences in structural lateralization, not only in somatomotor regions, but also in areas associated with high level cognitive control of action.

There is significant variation in the degree to which various religions systematically condemn same-sex ABSTRACT. The current research investigated whether priming students with a religious message affected their attitudes toward lesbians and gay men. Undergraduate students (N = 145) were randomly assigned to 1 of 3 conditions: participants in a religious-positive condition were primed with a biblical passage containing a loving message (e.g., "love one another, for love comes from God"), participants in a religious-negative condition were primed with a biblical passage containing an angry message (e.g., "God takes revenge on all who oppose him"), and participants in a control condition were primed with a neutral passage. After reading the priming passage, participants completed questionnaires assessing various measures of religiosity such as religiousness, spirituality, religious affiliation, extrinsic and intrinsic religious orientation, religious fundamentalism, and their attitudes toward lesbians and gay men. Consistent with previous research, religiosity was negatively related to attitudes toward lesbians and gay men (ps < .01). Self-identified Christians had more negative attitudes toward lesbians and gay men (p = .002, η p 2 = .12) than participants of other religious affiliations. However, there was no effect of the priming manipulation on attitudes toward lesbians and gay men (p = .88, η p 2 = .009).