The Effect of tDCS on Subcortical Brain Functioning

This research is being done to determine whether transcranial direct current stimulation (tDCS) can improve certain abilities related to cognition, emotion and/or physical functioning in individuals with subcortical brain damage.

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.

Parkinson's disease, Lewy body dementia, Korsakoff's syndrome, Subcortical Dementia, Huntington's Disease

Transcranial direct current stimulation using Anodal or Cathodal stimulation over the area of interest

Transcranial direct current stimulation (tDCS) that is ramped up and ramped down providing the sensation of tDCS without delivering the full amount of tDCS.

Inclusion Criteria: Fluent in the English language History of subcortical brain damage (patient group only) No known neurological or cognitive impairment (control group only) Exclusion Criteria: Appreciable deficits in hearing Schizophrenia, bipolar disorder, or major depression (normal controls only) Any neurological disorder associated with cognitive impairment or neuroanatomic abnormality (normal controls only) Language-based learning disorder (normal controls only) Dementia or Mini-Mental State Exam <24 for normal control participants Any implanted metal device (precludes use of tDCS) Any implanted cardiac pacemaker