Effect of a) muscimol and b) atomoxetine infusions into the anterior cingulate cortex (ACC), dorsal prelimbic (dPL), ventro-medial prefrontal cortex (vmPFC) and orbitofrontal cortex (OFC). Muscimol (0.5 μg/0.5 μl/side) significantly impaired stop accuracy in ACC and dPL. In this latter region, stop accuracy was decreased across SSDs whereas in the former, decomposition of the interaction revealed a significant effect only at −300 ms. Effects in OFC and vmPFC are likely to be caused by the drug’s effect on go accuracy (Figure 5). Atomoxetine (0.1 μg/0.5 μl/side) did not affect significantly stop accuracy in any PFC subregion at the dose tested suggesting that its effects are selective to the SSRT. (* p < .05, simple main effect analysis; # p < .01, main effect only)