Patients who are currently on psychotropic medications with the exception that PTSD patients currently taking SSRI s, benzodiazepines, or tricyclic antidepressants will be included. (Patients who are required to be free of all psychotropics must be off medication for 2 weeks, 6 weeks for fluoxetine. Additionally, PTSD patients on psychotropics other than SSRI s, benzodiazepines, or tricyclic antidepressants must be off medication for 2 weeks prior to testing. Patients will not be taken off medications for the purpose of the study)