Causal Role of Top-Down Theta Oscillations in Prioritization

Purpose: The purpose of this pilot study is to investigate the dynamics between theta and alpha oscillations in the control of working memory. These findings will be informative of what types of brain stimulation are most effective at modulating brain activity. Deep brain stimulation and transcranial magnetic stimulation are used for an increasing number of neurological and psychiatric disorders. Participants: Eligible participants are patients who have previously had electrodes implanted to monitor epilepsy (outside of research activity). 50 participants will be recruited, 25 participants for each phase of the study. Procedures (methods): The participants will perform a cognitive control task. During the task, rhythmic trains of direct cortical stimulation will be delivered to the frontal cortex alone or to the frontal and parietal cortex. Electrocorticography will be collected concurrent with stimulation.

Inclusion Criteria: * Able to provide informed consent * History of medically intractable epilepsy * Speak and understand English * For the stimulation session, the participant must have electrodes in the relevant locations Exclusion Criteria: * Current diagnosis of other neurological illnesses including ischemic stroke, intracerebral hemorrhage, brain neoplasm * Major systemic illness * Severe cognitive impairment - diagnosed by clinician in neuropsychiatric evaluation * Severe psychiatric illness * Excessive use of alcohol or other substances * Anything that, in the opinion of the investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study