1. In all contrasts, high SR+/SP− and SR+/N− scores were associated with brain activity peaking in the left ventral striatum. The peak activity for SR+/SP was localized more anterolaterally in the caudate head spreading into nucleus

accumbens and putamen, while the SR+/N− related peak activity was situated more posteromedially spreading into nucleus accumbens only. Both SR+/SP− and SR+/N− scores were associated with activity in the bilateral medial orbitofrontal cortex and left thalamus. In addition SR+/SP− was associated with activity in the left posterior hippocampus spreading into adjacent parahippocampal gyrus and fusiform cortex, right lateral occipital cortex and left opercular cortex while SR+/N− scores was associated with activity in the bilateral inferior temporal gyrus, left middle temporal gyrus, right inferior and middle frontal gyrus and the bilateral lateral orbitofrontal cortex. The right RT priming effect Epigenetics inhibitor was associated Ferroptosis activation with bilateral striatal activity (cluster

size: 409, x–y–z = 14–4–6, max Z-value = 3.8) where the left striatal activity was localized more ventrally compared to the right striatal activity. Striatal activation was not observed with the left RT priming effect as covariate. Multiple linear regression analyses with max Z-values from the 6 ROIs in the left ventral striatum associated with SR+/SP− and SR+/N−, showed that SR scores significantly increased brain activity while SP and N significantly HDAC inhibitor decreased brain activity and that a substantial portion of the variance was explained by SR, SP and N ( Table 5). The results support the Joint Subsystems Hypothesis, as adjusted SR scores, more than SR, predicted increased activity in the left ventral striatum. In addition, SR+/SP− scores predicted an increased right, but

not left, RT priming effect. The right RT priming effect was also associated with ventral striatal activity. This indicates that stronger reward associations were formed for right than for left primes and targets, most likely related to right-handedness. We observed that RTs were faster for right hand responses while there were more commission errors in left trials similar to previous reports (Avila & Parcet, 2002). Handedness reduces the precision and speed of the non-preferred hand (Flowers, 1975). Thus, successful trial completion seemed to yield reward associations and drive BAS related impulsivity in the present task. As hypothesized, high SR scores were associated with increased brain activity in the dopamine innervated ventral striatum, a central BAS structure (Pickering & Gray, 2001). The ventral striatal activity was elicited by unexpected reward cues, i.e., cue-primes and neutral trials targets which were both unforeseen and associated with successful trial completions. In comparison, neutral primes were not reward associated as indicated by their stimulus neutrality.