The anatomical and behavioural correlates of experience

Abstract

The effects of experience on developing and mature prefrontal brain circuitry and behaviour were investigated in rats using Ritalin, complex housing, and learning as tools. The results showed that Ritalin altered prefrontal cortical (PFC) circuitry and produced abnormal play behaviour and cognitive deficits into adulthood. Moreover, early stimulant exposure inhibited the robust anatomical changes typical after complex housing, demonstrating that early drug experience compromised cortical plasticity. Ritalin also altered adult PFC circuitry, but without enduring behavioural effects. Thus, it appeared that the mature brain was better able to compensate under adverse conditions. Nonetheless, novel experiences altered adult PFC circuitry with individual tasks producing unique patterns of change. Therefore, similar to other cortical regions the PFC was modified by experience. What was unique, however, was that experience-induced plasticity in the PFC appeared to be transient in adult animals, suggesting that once the task was learned the PFC was no longer required.