BEHAVIORAL NEUROIMAGING WITH POSITRON EMI SSION TOMOGRAPHY AND MAGNETIC-RESONANCE-IMAGING

Changes in regional cerebral blood flow (rCBF) during experimentally m odified psychological activation can be measured using radioactive lig ands with positron emission tomography (PET) and using magnetic resona nce principles with functional magnetic resonance imaging (fMRI). With PET it is possible to determine not only rCBF, but also metabolic cha nges, as well as the density and binding of several neuroreceptors. Th is can be done in conjunction with psychological and pharmacological c hallenge. fMRI is an imaging technique for perfusion-based signal inte nsities of the brain which does not involve radioactivity and gives be tter anatomical and temporal resolution than PET. Under appropriate ex perimental conditions, subjects' behavior and experience can be modifi ed while they are lying in a tomograph. These experiments can be used for the scientific investigation of cognitive constructs such as memor y and attention, or emotional processes. In this review, both function al neuroimaging techniques are assessed.