A Mechanistic Study to Investigate tDCS and Working Memory in MCI Patients

Inclusion Criteria * Age 60-95 years * Montreal Cognitive Assessment (MoCA) score 18 and above (scores will be adjusted for education) * Able to receive electrical stimulation * Ability to comprehend conversational voices * Adequate motor capacity to operate computer mouse and click-button in-scanner * Ability to participate in the intervention and attend training sessions Exclusion Criteria * Failure to provide informed consent * Contraindications to MRI recording (e.g., any kind of ferrous metallic stents or ferrous metal objects in the body, heart valve prosthesis, or other metal implants, claustrophobia, neurostimulation system, defibrillator, pacemaker, or other implanted device) * Left-handed, or left hand dominant * History of neurological, seizures, and psychiatric disorders, traumatic brain injury, incidence of stroke involving large vessel * Terminal illness with life expectancy less than 12 months, as determined by physician * Brain tumor or malformation or any foreign body known or previously identified in brain * Cancer in active treatment, besides skin cancer * Currently on GABAergic or glutamatergic medications, or on calcium or sodium channel blockers, which alter or block the ability of tDCS to facilitate tissue excitability * Unable to communicate because of severe hearing loss or speech disorder * Severe sensory impairment * Inability to communicate in English * Severe visual impairment, which would preclude completion of the assessment and/or intervention * No physical impairment precluding motor response or lying still for an hour in the scanner that could confound study findings * Moderate-to-severe depressive symptoms as defined by scoring 10 or above on the Geriatric Depression Scale (GDS)