Study of Direct Brain Recording and Stimulation for Memory Enhancement

Background: \- Epilepsy is a seizure disorder. Sometimes it is treated with surgery. During surgery, electrodes are placed on or in the brain. Researchers want to learn more about memory and the brain. They want to do tests on people who are having epilepsy surgery. Objective: \- To learn more about memory and brain function by recording brain cell activity during memory tasks. Eligibility: \- Adults age 18 - 65 who have medically intractable epilepsy and will have electrodes placed to identify the source of their seizures. They must be currently enrolled in protocol 11-N-0051. Design: * Participants may do memory tests before the electrodes are put in, while they are in place, and after surgery. Researchers may stimulate areas of the brain with small pulses of electricity. * Researchers will start recording brain activity at least 12 hours after electrodes are placed. They will record while participants are awake and asleep. They will record before, during, and after seizures. * Participants may have up to 3 testing sessions daily over the 1-3 weeks the electrodes are in place. Each session will last 20-60 minutes. * Participants will play games on a laptop. Sometimes they may use a button or joystick. This can be done in bed in the hospital. * Participants may be given a list of words and asked to recall them in a short time. * Participants may be given pairs of items and asked to remember how they are related. * Participants may be asked to learn their way around a virtual town on the computer. Their eye movements may be tracked by a small camera.

* INCLUSION CRITERIA: To be eligible for entry into the study, candidates must meet all the following criteria: * Be enrolled in 11-N-0051 Epilepsy Surgery. * Able to give informed consent. * Age greater than or equal to 18 years and less than or equal to 65 years EXCLUSION CRITERIA: Candidates will be excluded if they: -Have any disability that would limit their ability to perform study tasks that examine memory function.