<qa>  What is the radioligand used to measure neuroimmune activation in the living brainWe propose to determine whether neuroimmune activation is present in the living brains of patients with autism. Furthermore, given the heterogeneity of the autisms , as they are now called, we would like to determine whether neuroimmune activation is detectable in higher versus lower functioning patients with autismASDs. We propose to measure neuroimmune activation in the living brains of patients by utilizing positron emission tomography PET and the radioligand 11CPBR28. This radioligand binds translocator protein TSPO, which is over-expressed in activated microglia and reactive astrocytes, and has been demonstrated as a reliable marker of neuroimmune activation in various neuropsychiatric disorders. Because the majority of patients with autismASD will require propofol sedation to remain motionless for the two hour scan, we will include a control arm with healthy volunteers without then with propofol in order to determine the effects of propofol on 11CPBR28 uptake. NIH has developed a setup in the clinical center for administering sedationanesthesia in a safe manner, making this important study possible. 