<qa>  What is the name of the group that will be excluded from the screening?Subjects: 75 subjects with PTSD ages 18-80, 75 age and gender matched normal controls, and 75 age and gender matched subjects with combat history but no PTSD will be recruited. Subjects will be screened and excluded for Axis I and II disorders other than PTSD for the patient group, for significant medical illness, and for auditory or visual impairment. 