Brain Connectivity

The investigators aim is to investigate the brain's dynamic complexity across three phases of an ovarian stimulation cycle (basal, pre-OPU, mid-luteal), to observe the impact of externally administered hormones, and compare it with the corresponding phases of a natural menstrual cycle (early follicular, pre-ovulatory, mid-luteal) in the same woman. Brain activity patterns will be examined using resting-state fMRI in a sample of young, healthy, naturally cycling women.

Transcranial magnetic stimulation (TMS) is increasingly being applied to effectively treat mental illness, however efforts to quantify the effects of TMS on the network architecture of the brain have largely been limited in scope and tied to specific neurologic and psychiatric disorders. The objective of the current work is to build and validate a whole-brain, domain-general model of brain connectivity changes following TMS, based on physical models of the current distribution at the cortex. PUBLIC HEALTH RELEVANCE: This work is relevant to public health because it will provide direct evidence that brain connectivity changes following neuromodulatory TMS vary as a function of the current density at the cortex, which can be used to predict psychiatric symptom change following neuromodulatory TMS.

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.

The goal of this observational study is to identify the characteristics of brain functional connectivity in refractory constipation and fluoxetine-sensitive patients. The main questions it aims to answer are: * Investigating the alterations in brain functional connectivity in patients with refractory constipation and fluoxetine-sensitive patients * Assessing the predictive value of brain functional connectivity regarding the efficacy of fluoxetine and standard protocol treatments for constipation. Participants will receive: * Standard physiological and psychological assessments of constipation * BOLD-fMRI tests * Standard protocol and fluoxetine treatment If there is a comparison group: Researchers will compare: Refractory group/Fluoxetine sensitive group to see the specific brain alterations.

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.