In contrast to the experiments showing how a lack of use can degrade brain function, several studies in intact animals have shown how plasticity can be induced within
specific brain regions through extended training. Monkeys trained to perform fine digit movements by retrieving small food pellets out of a well had an increase in digit representation areas within primary motor cortex. Similarly, rats trained to reach outside of their cage to retrieve food rewards had an increase in distal forepaw representations within motor cortex . Synaptogenesis and increased synaptic responses were found within these same cortical
areas. Reorganization of representations within auditory and somatosensory cortex has