Abstract
Positron emission tomography (PET) and functional magnetic resonance imaging (MRI) have been introduced into the field of brain science as an noninvasive approach to visualize brain function, focusing on the regional distribution of neuronal activity and its connectivity. Measurement of regional cerebral blood flow with PET has been established for mapping human brain function covering the whole brain with various task conditions. Recently introduced functional MRI technique can also detect the signal changes due to the local increase of blood flow by brain activation. Both PET and MRI provide similar activation patterns in cerebral cortical areas, and the study should be designed by considering the characteristics of each modality. Although PET continues to play a major role in imaging of the neurotransmission process, the efforts are now being made to apply this exciting technique to clinical diagnosis by means of single photon emission computed tomography (SPECT). Neuroreceptor imaging is now applied not only for differential diagnosis of neurological diseases but also for determination of optimal dose of appropriate therapeutic drugs in psychiatric patients. Combined use of activation studies with neurotransmission imaging will provide a new insight in understanding the brain mechanism of emotion and behavior.
