REGIONAL CEREBRAL BLOOD FLOW (RCBF RCBF): Regional cerebral blood flow monitoring may help boost the validity of the regional localization theory, in which specific parts of the brain control specific functions.. measure of the blood flow in a specific area of the brain, using positron emission tomography (PET scans) and/or single photon emission computed tomography.
If a dog goes on his back to you he is accepting you as his master. This is part of the answer but here's a little more in-depth version as reported by USA Today. In general, dogs lie on their back for three reasons.
If a dog's tail is down, he may be feeling shy and trying not to be noticed. However, if his tail is arched upward, it signifies that he is feeling happy and welcoming. If a dog's tail is down but not hidden between his legs, it usually means that the dog is not feeling well; it may signify an injury or a stomach ache. Although a tail between the legs is usually considered a position of submissiveness, it is also fear-filled position.