Answer to Question 1
Answer: Brain cells require glucose as fuel for activity. 2-DG, like glucose, is taken up into neurons, but cannot be used for energy. If a radioactive version of 2-DG is injected into an animal, radioactive 2-DG molecules will accumulate in the brain as a function of the relative activity of those cells. Autoradiography will reveal the presence of radioactive molecules in the brain, with a more intense signal in regions that were more active and a less intense signal in less active regions.
Answer to Question 2
Answer: The method can be used to stimulate or inhibit neurons in a specific brain region. Two distinct photosensitive proteins have been identified. ChR2 controls a sodium channel and is sensitive to blue light. NpHR controls a chloride channel and is sensitive to yellow light. The proteins are inserted into a brain region and the response to blue or yellow light is noted. Typically, blue light activates and yellow light inhibits neuron activity.
Development of the human brain.
The Cerebellum and the Brain Stem
Sickled and normal red blood cells.
Summary of Cytokine Activity
Fighter Cells
Hormone Activity