We can use cell stains to predict overall health of the tissue. Imaging look at live brains and how they behave: Ct"s : uses computers to enhance computer images. Pet scans : look at patterns of activation. Different parts of the brain light up for different tasks. Frmi : take measurments of blood flowif an area is receiving more blood flow then its more active. Certain areas of brain are activated for particular tasks. Lesion studies are used to destroy a particular area of the brain to find out its role. Coronoal cutting through from top to bottom horizontal section- brain cut in half. blood supply really important for braineven though its really smallblood demands are huge. In central nervous system, there are three layers. Peripheral has only two layers, the arachnoid layer is missing. (page 7) Brain has some empty spaces that lack brain matter.