A lung scan is a type of nuclear scanning test. It is most often used to find a pulmonary embolism. This is a blood clot that prevents normal blood flow in the lung. Two types of lung scans are usually done together: Ventilation scan. During this scan, you inhale a radioactive tracer gas or mist. Pictures from this scan can show areas of the lungs that aren't getting enough air or that hold too much air.
One interesting theory on the cause of manic depression or bipolar disorder is that there is a super-fast biological clock located in the hypothalamus, in the center of the brain, which is actually a tiny cluster of nerves called the supra chiasmatic nucleus or SCN.
Bipolar disorder, formerly called manic depression, causes extreme mood swings that include emotional highs (mania or hypomania) and lows (depression).