• INCLUSION CRITERIA FOR SMOKERS:

  1. 21-40 year old males
  2. smoke 10-25 cigarettes per day on average for at least 2 years
  3. urine cotinine level greater than or equal to 200 ng/ml (NicAlert reading greater than or equal to 4)
  4. estimated IQ score greater than or equal to 85 (competent to give informed consent)
  5. medically and psychologically healthy as determined by screening criteria.

EXCLUSION CRITERIA FOR SMOKERS:

1. interest in reducing or quitting tobacco use
2. treatment for nicotine dependence in the past 3 months
3. history of drug or alcohol dependence
4. consumption of more than 15 alcoholic drinks per week during the past month
5. use of any illicit drug during the past 6 months
6. current use of any medication that would interfere with the protocol
7. under the influence of a drug or alcohol at experimental sessions
8. HIV positive
9. history of psychotropic medications
10. history of head injury with unconscious longer than 5 minutes
11. implantable device or foreign body that would make an MRI examination unobtainable
12. MRI abnormality judged clinically significant by the PI
13. use of any investigational medication or device within the previous 30 days
14. donation at least 450 ml of blood or equivalent levels of plasma within the previous 30 days
15. exposure to ionizing radiation that, in combination with the study tracer, would result in a cumulative exposure exceeding 5 rem in one calendar year
16. any subject judged by the PI to be inappropriate for the study.
17. chronic pulmonary disease, including COPD, bronchitis, asthma, and emphysema

INCLUSION CRITERIA FOR NONSMOKERS:

1. 21-40 year old males
2. smoked 1-20 cigarettes in their life and none in past year
3. urine cotinine level less than 30 ng/ml (NicAlert reading less than or equal to 1)
4. estimated IQ score greater than or equal to 85 (competent to give informed consent)
5. medically and psychologically healthy as determined by screening criteria.

EXCLUSION CRITERIA FOR NONSMOKERS:

1. use of any tobacco products in the past year
2. history of drug or alcohol dependence
3. consumption of more than 15 alcoholic drinks per week during the past month
4. use of any illicit drug during the past 6 months
5. current use of any medication that would interfere with the protocol
6. under the influence of a drug or alcohol at experimental sessions
7. HIV positive
8. history of psychotropic medications
9. history of head injury with unconscious longer than 5 minutes
10. implantable device or foreign body that would make an MRI examination unobtainable
11. MRI abnormality judged clinically significant by the PI
12. use of any investigational medication or device within the previous 30 days
13. donation of at least 450 ml of blood or equivalent levels of plasma within the previous 30 days
14. exposure to ionizing radiation that, in combination with the study tracer, would result in a cumulative exposure exceeding 5 rem in one calendar year
15. any subject judged by the PI to be inappropriate for the study.
16. chronic pulmonary disease, including COPD, bronchitis, asthma, and emphysema