Anatomy of Subcortical Structures Predicts Age-Related Differences in Skill Acquisition.

Skill acquisition capabilities vary substantially from one individual to another. Volumetric brain studies have demonstrated that global volume of several subcortical structures predicts variations in learning outcome in young adults (YA) and older adults (OA). In this study, for the first time, we utilized shape analysis, which offers a more sensitive detection of subregional brain anatomical deformations, to investigate whether subregional anatomy of subcortical structures is associated with training-induced performance improvement on a bimanual task in YA and OA, and whether this association is age-dependent. Compared with YA, OA showed poorer performance, greater performance improvement, and smaller global volume and compressed subregional shape in subcortical structures. In OA, global volume of the right nucleus accumbens and subregional shape of the right thalamus, caudate, putamen and nucleus accumbens were positively correlated with acquisition of difficult (non-preferred) but not easy (preferred) task conditions. In YA, global volume and subregional shape of the right hippocampus were negatively correlated with performance improvement in both the easy and difficult conditions. We argue that pre-existing neuroanatomical measures of subcortical structures involved in motor learning differentially predict skill acquisition potential in YA and OA.

Normal amygdala morphology in dissociative identity disorder.

Studies investigating the structure of the amygdala in relation to dissociation in psychiatric disorders are limited and have reported normal or preserved, increased or decreased global volumes. Thus, a more detailed investigation of the amygdala is warranted. Amygdala global and subregional volumes were compared between individuals with dissociative identity disorder (DID: n = 32) and healthy controls (n = 42). Analyses of covariance did not show volumetric differences between the DID and control groups. Although several unknowns make it challenging to interpret our findings, we propose that the finding of normal amygdala volume is a genuine finding because other studies using this data-set have presented robust morphological aberrations in relation to the diagnosis of DID.

Differences in Brain Volume between Metabolically Healthy and Unhealthy Overweight and Obese Children: The Role of Fitness.

The aim of this study was to examine whether metabolically healthy overweight/obese children have greater global and regional gray matter volumes than their metabolically unhealthy peers. We further examined the association between gray matter volume and academic achievement, along with the role of cardiorespiratory fitness in these associations. A total of 97 overweight/obese children (10.0 ± 1.2 years) participated. We classified children as metabolically healthy/unhealthy based on metabolic syndrome cut-offs. Global and regional brain volumes were assessed by magnetic resonance imaging. Academic achievement was assessed using the Woodcock-Muñoz standardized test. Cardiorespiratory fitness was assessed by the 20 m shuttle run test. Metabolically healthy overweight/obese (MHO) children had greater regional gray matter volume compared to those who were metabolically unhealthy (MUO) (all p ≤ 0.001). A similar trend was observed for global gray matter volume (p = 0.06). Global gray matter volume was positively related to academic achievement (ß = 0.237, p = 0.036). However, all the associations were attenuated or disappeared after adjusting for cardiorespiratory fitness (p > 0.05). The findings of the present study support that metabolically healthy overweight/obese children have greater gray matter volume compared to those that are metabolically unhealthy, which is in turn related to better academic achievement. However, cardiorespiratory fitness seems to explain, at least partially, these findings.

Subcortical Volume Loss in the Thalamus, Putamen, and Pallidum, Induced by Traumatic Brain Injury, Is Associated With Motor Performance Deficits.

BACKGROUND: Traumatic brain injury (TBI) has been associated with altered microstructural organization of white matter (WM) and reduced gray matter (GM). Although disrupted WM organization has been linked to poorer motor performance, the predictive value of GM atrophy for motor impairments in TBI remains unclear. OBJECTIVE: Here, we investigated TBI-induced GM volumetric abnormalities and uniquely examined their relationship with bimanual motor impairments. METHODS: 22 moderate to severe TBI patients (mean age = 25.9 years, standard deviation [SD] = 4.9 years; time since injury = 4.7 years, SD = 3.7 years) and 27 age- and gender-matched controls (mean age = 23.4 years; SD = 3.8 years) completed bimanual tasks and a structural magnetic resonance imaging scan. Cortical and subcortical GM volumes were extracted and compared between groups using FreeSurfer. The association between bimanual performance and GM volumetric measures was investigated using partial correlations. RESULTS: Relative to controls, patients performed significantly poorer on the bimanual tasks and demonstrated significantly smaller total GM as well as overall and regional subcortical GM. However, the groups did not show significant differences in regional cortical GM volume. The majority of the results remained significant even after excluding TBI patients with focal lesions, suggesting that TBI-induced volume reductions were predominantly caused by diffuse injury. Importantly, atrophy of the thalamus, putamen, and pallidum correlated significantly with poorer bimanual performance within the TBI group. CONCLUSIONS: Our results reveal that GM atrophy is associated with motor impairments in TBI, providing new insights into the etiology of motor control impairments following brain trauma.