It was pre-determined that volunteers reacted similarly to rewards, thereby eliminating that factor as interfering with the outcome. The memory test after the 90-minute break resulted in the sleep group performing better on an overall basis, but both groups were at par when it came to the most highly rewarded picture pairs. But 3 months later, the sleep group excelled in the latter test and was shown to be more confident than the wake group. Magnetic resonance imaging (MRI) proved that people in the sleep group had more activity in the hippocampus - a small area of the brain critical for forming memories. This phenomenon sent “slow spindles” into motion, which helps to consolidate memory, as well as a powerful link between hippocampus and two other areas of the brain involved in memory consolidation and reward processing: the medial prefrontal cortex and the striatum.