The study was approved by the regional ethical committee, and adhered to the Helsinki Convention. Fifteen healthy female volunteers without MRI contraindications and no history of neurological or psychiatric disease provided written informed consent. One participant was excluded due to technical errors. All remaining subjects were right-handed; laterality index of 80.2 ± 12.5 (Oldfield, 1971). Each participant completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ) which is based on the Reinforcement Sensitivity Theory (Torrubia, Avila, Molto, & Caseras, 2001).

SPSRQ measures sensitivity to reward (SR), i.e., BAS reactivity, and sensitivity to punishment (SP), a combined measure of FFFS and BIS reactivity. The Joint Subsystems Hypothesis was not 17-AAG chemical structure formulated specifically to expect differential impacts of BIS and FFFS on BAS (Corr, 2001 and Corr, 2004). Since FFFS and BIS serve different adaptive purposes, it is important to investigate the PS-341 chemical structure unique contributions from each system. However, there was no validated Reinforcement Sensitivity Theory derived measure separating BIS and FFFS, and we thus decided to apply neuroticism (N) from the Eysenck Personality Questionnaire (Eysenck & Eysenck, 1975) as a supplement to SP. A priori, SP should lie closer to FFFS and N closer to BIS because

SP places a stronger emphasis on fear related avoidance compared to N which emphasizes anxious rumination. Adjusted BAS reactivity measures, SR+/SP− (BAS-SP scores) and SR+/N− (BAS-N scores) were calculated and subsequently used to test if the Joint Subsystems Hypothesis is a more sensitive measure of activation of dopaminergic innervated brain structures than the original Reinforcement Sensitivity Theory. A priming task based on a Posner task (Avila & Parcet, 2002) was adapted for event-related fMRI and compiled in E-Prime

(Psychology Software Tools, Pittsburgh, USA). The task stimuli consisted of cue-primes, i.e., two small hatches pointing left or right (<< or >>), neutral primes, i.e., two small hatches Rebamipide pointing to the center (><), and target stimuli, i.e., one larger hatch pointing left or right (< or >). A trial was defined as valid if the target was preceded by a cue-prime pointing in the same direction as the target, invalid if preceded by a cue-prime pointing in the opposite direction, and neutral if preceded by a neutral prime. Each prime was displayed for 50 ms followed by a blank screen for 450 ms before the target presentation. This constituted a stimulus onset asynchrony of 500 ms, which is adequate for exploring reward sensitivity (Avila & Parcet, 2002). The target was displayed for 500 ms, followed by a 2600 ms rest period plus null-events of different lengths (1800, 3600, 5400 and 7400 ms).