The Effect of Transcranial Direct Current Stimulation on Subcortical Brain Functioning

While cortical brain structures are thought to be responsible for higher level cognitive functioning (i.e., perception, thoughts, language, memory, attention, and processing), subcortical brain regions (i.e., amygdala, midbrain, hippocampus, and thalamus) are generally believed to be responsible for more fundamental bases of such functions. A significant fraction of the population suffer from disabling disorders and diseases (i.e., Parkinson's disease, subcortical dementia, hypoxic brain damage) that affect subcortical areas. Despite their prevalence, very little success has been achieved in treating such impairments effectively.

This study has two main goals. One is to examine the effect of stimulation on a variety of subcortical functions (i.e., level of alertness, mood, cognition, and motor responding). A second goal is to examine the effects of varying some of the stimulus parameters of tDCS, notably the placement of the electrodes and the duration and frequency of application of current.

Adult participants with a confirmed diagnosis of subcortical brain damage, as well as healthy adults will be randomly assigned to anodal and cathodal stimulation in a counterbalanced order, and both will engage in simple behavioral tasks and/or physiological monitoring. These tasks will be specific to the deficit of interest.