Mapping accumulative wholebrain activities during environmental enrichment with manganeseenhanced magnetic resonance imaging Abstract   An enriched environment (EE) provides multidimensional stimuli to the brain. EE exposure for days to months induces functional and structural neuroplasticity. In this study, manganeseenhanced magnetic resonance imaging (MEMRI) was used to map the accumulative wholebrain activities associated with a 7day EE exposure in freelymoving adult male mice, followed by cFos immunochemical assessments. Relative to the mice residing in a standard environment (SE), the mice subjected to EE treatment had significantly enhanced regional MEMRI signal intensities in the prefrontal cortex, somatosensory cortices, basal ganglia, amygdala, motor thalamus, lateral hypothalamus, ventral hippocampus and midbrain dopaminergic areas at the end of the 7day exposure, likely attributing to enhanced Mn2 uptaketransport associated with brain activities at both the regional and macroscale network levels. Some of, but not all, the brain regions in the EEtreated mice showing enhanced MEMRI signal intensity had accompanying increases in cFos expression. The EEtreated mice were also found to have significantly increased overall amount of food consumption, decreased body weight gain and upregulated tyrosine hydroxylase (TH) expression in the midbrain dopaminergic areas. Taken together, these results demonstrated that the 7day EE exposure was associated with elevated cumulative activities in the nigrostriatal, mesolimbic and corticostriatal circuits underpinning reward, motivation, cognition, motor control and appetite regulation. Such accumulative activities might have served as the substrate of EErelated neuroplasticity and the beneficial effects of EE treatment on neurologicalpsychiatric conditions including drug addiction, Parkinsonu0027s disease and eating disorder.

Striatal iron content is linked to reduced frontostriatal brain function under working memory load Abstract   Nonheme iron accumulation contributes to agerelated decline in brain structure and cognition via a cascade of oxidative stress and inflammation, although its effect on brain function is largely unexplored. Thus, we examine the impact of striatal iron on dynamic range of BOLD modulation to working memory load. Nxe2x80xafxe2x80xaf166 healthy adults (age 20xe2x80x9394) underwent cognitive testing and an imaging session including nback (0, 2, 3, and 4back fMRI), R2*weighted imaging, and pcASL to measure cerebral blood flow. A statistical model was constructed to predict voxelwise BOLD modulation by age, striatal iron content and an agexc2xa0xc3x97xc2xa0iron interaction, controlling for cerebral blood flow, sex, and task response time. A significant interaction between age and striatal iron content on BOLD modulation was found selectively in the putamen, caudate, and inferior frontal gyrus. Greater iron was associated with reduced modulation to difficulty, particularly in middleaged and younger adults with greater iron content. Further, ironrelated decreases in modulation were associated with poorer executive function in an agedependent manner. These results suggest that iron may contribute to differences in functional brain activation prior to older adulthood, highlighting the potential role of iron as an early factor contributing to trajectories of functional brain aging.