A pet study of human skill learning: Changes in brain activity related to learning an orientation discrimination task

Using O-15-water 3D positron emission tomography we investigated the effect of training in orientation discrimination upon cerebral activity in health y human adults. When subjects are trained in this discrimination task, they learn the visuo-motor stimulus-response association required by the task a nd they increase their perceptual abilities in orientation discrimination. The present study was designed to investigate the rCBF modifications relate d to both these learning processes induced by training in orientation discr imination. PET data were acquired on two separate days (before and after tr aining). Comparing the activation pattern related to orientation discrimina tion before and after the training period we observed activity decreases lo cated in the left cerebellar cortex;, in the right precentral gyrus and bil aterally in the fusiform gyri. The only region showing an activity increase was located in the body of the right caudate nucleus. These findings confi rm the role of the neostriatum in skill learning and highlight the importan ce of mechanisms resulting in cortical and cerebellar neuronal activity dec reases in this type of learning.