 - Central nicotinic acetylcholine receptors nAChRs are primary targets for the action of nicotine. In addition to being involved in tobacco dependence, they are also involved in a variety of brain disorders, including Alzheimers and Parkinsons diseases. Researchers are interested in developing better ways to study the action of nAChRs to improve treatments for smoking cessation and other problems affected by these receptors. These new study methods may involve different approaches to positron emission tomography PET scanning, which can show brain activity related to nAChRs. 