Table 1.

Exclusion criteria of the study

1. Non-healthy individuals

• Previous medical history for any chronic condition in the last three months, active disease, or abnormal physical examination as verified by a qualified physician.

2. Casual smoking

• >6 cigarettes per day.

3. Frequent, heavy alcohol consumption

• >21 units/week.

4. Frequent, heavy caffeine consumption

• >4 caffeinated drinks/day.

5. Gender: female

6. Age: < 18 and > 60 years old

7. Shift workers

8. Participation in an investigational drug trial within the past two months

9. Intake of any medication (prescribed, over the counter or recreational) including topical steroids and inhalers, within 48 hours of the study initiation

• Urine sampling for testing for drugs of abusea

Stage 1 (pharmacological validation) only

10. Needle phobia

Stage 2 (neurobehavioural investigation) only

11. Left-handed or ambidextrous

• Tested with the Edinburgh Handedness Inventory [13]

12. Dyslexia

13. Claustrophobia

14. Contraindication to MRI scan

15. Non English-language users

^aUrine sampling for testing for drugs of abuse takes place during the recruitment process. In addition, during study stage 2 (neurobehavioural investigation), urine sampling is repeated prior to starting the trial on day 1 of each of the three study arms, as well as prior to the scanning session on day 5 on each of the three study arms. A seven-drug (multi-panel) dip and read immunoassay is being used, offering high accuracy in detecting cocaine, amphetamine, methamphetamine, tetrahydrocannabinol (cannabis), opiates, barbiturates and benzodiazepines (SureScreen Diagnostics®)