The hippocampus is located in the medial temporal lobe below the cortex and plays an important role in memory consolidation, emotions, navigation, and spatial orientation. Three studies were summarized. The first found that more physically fit children had a larger hippocampus. The second found that long-term ecstasy users had a smaller hippocampus. The third found that Gulf War veterans who had recovered from PTSD had larger hippocampal volumes than those who had not recovered. Damage to the hippocampus can cause amnesia or memory loss and may eventually lead to Alzheimer's disease.