Figure 1.

The two axes of behavioral control – affect or valence – running from punishment to reward, and effect or action, running from motor inhibition to motor activation. For an instrumental control system (in blue) these two axes are mutually independent. Therefore, an instrumental controller should learn equally well to invigorate action to obtain a reward (‘go to win’), to invigorate action to avoid a punishment (‘go to avoid losing’), to inhibit action to avoid punishment (‘no go to avoid losing’), and to inhibit action to obtain a reward (‘no go to win’). By contrast, action and valence are coupled in a Pavlovian control system (in red) so that reward is associated with action invigoration (approach and engagement) whereas punishment is associated with action inhibition (withdrawal and inhibition). At the neuronal level, the same dual association between action and valence may be observed within ascending monoaminergic systems. The dopaminergic system (DA) is involved in generating active motivated behavior and reward prediction, whereas the serotonergic system (5HT) appears affiliated with behavioral inhibition, potentially in aversive contexts.