Increasing research is focused on conditions that precede the clinical diagnosis of Alzheimer's disease (AD) in order to detect patients at risk for early intervention. One such condition is mild cognitive impairment (MCI). Functional magnetic resonance imaging (fMRI) studies in this group of patients have reported increased activation in the Medial Temporal Lobe (MTL) during performance of memory tasks. The functional significance of increased activation is unclear. One possibility is that greater activity reflects the increased effort needed in order to maintain performance, and as such would be a compensatory response. An alternative possibility is that increased activation reflects aberrant physiology related to the disease process itself and as such would be a sign of greater underlying disease severity and would interfere with brain function.