Abstract
The application of positron emission tomography (PET) to the study of the functioning human brain provides researchers with a noninvasive procedure which allows in-vivo quantification of physiological and biochemical processes underlying cognition (Gur, 1985; Gur, 1987; Reivich, Alavi, Gur, and Greenberg, 1985). Techniques from a diverse set of fields must be effectively integrated for the application of PET technology. Organic chemistry and biochemistry make possible the synthesis of trace levels of the biological and physiological substrates which are used to examine biochemical pathways in the brain without perturbing the normal physiology. Physics and engineering are essential for the development of the equipment needed to measure the concentration of the radionuclides in tissue. Mathematics and physiology are used for the development of models to describe the behavior of those radioactive tracer agents. Medicine and neuropsychology pose the clinically relevant questions that can be answered by this technology (Mazziotta & Phelps, 1985a; Phelps, Mazziotta, & Huang, 1982; Phelps, Mazziotta, Schelbert, Hawkins, & Engel, 1985; Sokoloff, 1985). The role of the neuropsychologist is crucial in the assessment of baseline cognitive functioning, the development of experimental design and quantification of behavioral stimulation during scanning, and the evaluation of the effects of the imaging process, itself. In this chapter, we will describe the basic principles of PET and review current findings of PET applications to the study of cognitive functioning. In addition, we present data on new behavioral activation paradigms which have recently been developed to further elucidate the relationships between cognitive/neuropsychological functioning and metabolic activity within specific cerebral regions.