Introduction and aims: Stress and corticosteroid exposure are associated with changes in the human and animal hippocampus. In animals, phenytoin prevents dendritic changes in the hippocampus secondary to corticosterone. We propose to use functional magnetic resonance imaging (fMRI) to explore the effects of 3-days of exposure to placebo, hydrocortisone, phenytoin and hydrocortisone plus phenytoin on hippocampal activation. If phenytoin attenuates the effects of hydrocortisone, we will use this model system to explore other potential neuroprotective agents