Dr. Alexa Morcom and Prof. Rik Henson investigate the elevated prefrontal cortex activity that is often observed in healthy older adults despite declines in their memory and other cognitive functions. They compare two leading models of brain ageing: that the frontal cortex is either compensating for impairments elsewhere in the brain; or alternatively, that structural or neurochemical changes lead to less efficient and less specific use of resources. Using sophisticated multivariate statistical modelling of the data, the authors present evidence of the latter explanation.