Answer to Question 1
Answer: One way is to use autoradiography in which brain tissue is exposed to a solution of a radioactive receptor antagonist. In the second method, antibodies are proteins produced by white blood cells that are specific to another protein or peptide (antigen). Receptors are comprised of proteins (antigens), for which an antibody can be developed and tagged using a marker such as a fluorescent marker (or dye). A slice of brain tissue is incubated with the antibody/marker so that the antibody will attach to the antigen (receptor) with each location indicated by the presence of a fluorescent signal.
Answer to Question 2
Answer: In the efferent tracing procedure, a chemical such as PLA is injected into a brain site, taken up by dendrites and transported out to the axons. Immunocytochemistry is used to visualize the places that receive axons from the neurons of the injection site. In contrast, afferent tracing involves injecting a chemical, such as fluorogold, which is taken up by axon terminal buttons and transported backwards to the cell bodies. This procedure thus identifies the neurons that innervate a specific brain region.
Multiple sclerosis (MS). (a) A disease characterized by the gradual development of small areas of ha
Brain
Autoradiogram of a Rat Brain
Brain Hemisphere Activity
In the retina, there are two types of light receptor cells: Rods are sensitive to differences in lig