Brain Structure

Investigators propose to study youth across the spectrum of body mass index (BMI) and dysglycemia. This approach will allow investigators to disentangle the relationship of key features of type 2 diabetes (T2D) risk (e.g. obesity) with intermediary physiologic changes (e.g. insulin resistance, inflammation, β-cell dysfunction and dysglycemia) that pose a risk for the brain. Investigators will determine which of these factors are most associated with differences in brain structure and function among groups, over time, and how these effects differ from normal neurodevelopment.

This is an assessor-blinded neurophysiological study. Participants will be randomly assigned to a perturbation-based training (PBT) or a walking (control) group. Changes in postural stability and neurophysiology in the brain following PBT compared to walking exercise without perturbation will be investigated.

Ankle control is essential to safe over-ground navigation for humans. Middle- aged and older adults and patients with stroke whose ankle control is poor often lose their balance or fall. Transcranial direct current stimulation (tDCS) is an emerging non-invasive brain stimulation technology that has great potential to be applied to neurorehabilitation; however, the optimization of its applications still needs further studies. The aims of this project are to compare the effects of anodal tDCS (AtDCS) applied to the primary motor cortex (M1) contralateral to the moving leg (cM1), posterior parietal cortex (PPC) contralateral to the moving leg (cPPC), and cerebellar cortex (CBM) ipsilateral to the moving leg (iCBM) on motor learning, motor adaptation, and brain connectivity in healthy middle-aged and older adults and hemiparetic patients with chronic subcortical stroke.