Non-invasive physiological measures of in vivo brain function, derived from positron emission tomography (PET) and functional magnetic resonance (fMRI), are now standard tools in cognitive neuroscience. These techniques provide a powerful context for addressing critical questions regarding both the localization and mechanisms of higher brain functions. A general overview of the history and development of imaging techniques in relation to cognitive science is that of Posner & Raichle (1994). The conceptual background and methodological approaches available for neurobiological based psychiatric research, in conjunction with functional imaging, provides the focus for the present review.
Major psychiatric disorders, such as schizophrenia and depression, represent disturbances at the highest level of brain function. Providing a neurobiological account of these conditions presents the most formidable problem in clinical neuroscience. Questions posed by neurobiological perspectives on psychiatric disorders are necessarily embedded in theoretical assumptions about how we think that the brain works. From this, it follows that an important limiting factor in any neurobiological account of psychiatric disease is the stage of development and theoretical conceptualization of brain function in general.