Reminiscing about happy times is rewarding to the brain, and people will even give up money for the chance to enjoy some nostalgia.

Mauricio Delgado and his colleagues at Rutgers University in Newark, New Jersey, asked volunteers to recall happy and neutral memories while their brains were scanned using functional magnetic resonance imaging. Participants spent more time recalling happy memories, and when doing so, their brain activity patterns were similar to those seen in people receiving money. When offered a small amount of money to recall a positive memory and a larger amount for a neutral memory, the volunteers were more likely to choose the happy memory.

The researchers say that recalling good memories could be useful for improving mood.

Neuron (2014)