Neuroimaging of priming: New perspectives on implicit and explicit memory

Priming refers to a change in Me ability to identify or produce an item as a consequence of a specific prior encounter. Priming has been studied exten sively in cognitive studies of healthy volunteers, neuropsychological inves tigations of brain-damaged patients, and, more recently, studies using mode m functional neuroimaging techniques such as positron emission tomography a nd functional magnetic resonance imaging. We review recent neuroimaging stu dies that have converged upon the conclusion that priming is reliably accom panied by decreased activity in a variety of brain regions. The establishme nt of this cortical signature of priming is beginning to generate new hypot heses concerning the relation between priming and explicit retrieval, which we illustrate by considering recent experiments on within-and cross-modali ty priming.