Figure 1.
Visual Stop-signal task (VSST): Participants responded to the direction of a central green arrow (“Go-stimulus”), and withheld their response when the arrow turned red (“Stop-stimulus”) in the classic variant of the task.
In the control variant, participants were told to respond as they would normally to the direction of the “Go-stimulus” irrespective of whether it was followed by a “Stop-stimulus”. In both variants of the VSST, each trial began with the presentation of a fixation cross of varied duration. On “Stop-trials”, the “Go-stimulus” was replaced, following a varied Stimulus Onset Asynchrony (SOA), by the “Stop-stimulus”. In the classic variant, the SOA increased or decreased by 50msec as a function of whether participants were correct or not, respectively, at inhibiting their response to the “Stop-stimulus”. In the control variant, the SOA also varied in 50msec increments, but randomly. The total stimulus-display duration (TSD) was 800ms.
Figure 2.
Activations reflecting the main effect of group from the one-way ANOVA Sstop>Go 2nd-level model (thresholded at p < 0.005, k = 13; scale represents F statistic; see results section for details).
Linear increases were found in inferior frontal gyrus pars orbitalis (Figure 2A), while linear reductions were observed in an inferior temporal cluster (Figure 2B). Non-linear, overall reduction in activation following both doses of alcohol was observed in SMA proper (Figure 2C).
Figure 3.
Activations arising from the planned group comparison 2nd- level models (thresholded at p < 0.005, k = 13; scale represents F statistic; see results section for details). Comparison of the Sstop>Go contrast between the low-dose and placebo groups (Figure 3A), and the high-dose and placebo groups (Figure 3B and 3C).