NEW APPROACHES TO IMAGING BASED ON EFFECTS OF NEUROTOXINS

Positron and single-photon emission tomography at present visualize on ly loss of overall brain substance, with a few exceptions. This has im proved diagnostic accuracy in the clinic but further improvements coul d be made. By using toxins, such as volkensin, brain tissues can be pr oduced that are deficient in various subpopulations of cortical pyrami dal neurone. Experimental lesions in rats and quantitative autoradiogr aphy were used to investigate the cellular localization of receptors. Lesions were produced by intrastriatal or intracortical injections of volkensin to destroy corticofugal and corticortical pyramidal neurones respectively. Volkensin treatment caused significant loss of pyramida l neurones which was accompanied by reduced binding to certain recepto rs. Results are discussed in terms of the biology of cortical pyramida l neurones and in vivo imaging in Alzheimer's disease.