Table 1.

Properties of the cholinergic systems underlying reward enhancement and inhibition.

Threshold Level	Timing	Reward [and Affective] Effects	Description
Lower	Rapid, Short-  Term	Enhancement  [positive]	Under baseline, unstimulated conditions (Figure 1, State A), short-term, increases in VTA-accumbal cholinergic transmission that rise above a lower cholinergic threshold promote positive affective states, increasing the probability of reinforcement (Figure 1, State A is advanced to B).
Upper	Delayed,  accumulates  over Time	Inhibition  [negative]	Larger and more prolonged increases in VTA-accumbal cholinergic transmission that exceed a second, higher value, have an opposite effect, facilitating negative affective states, and decreasing the likelihood of reinforcement (State B is advanced to C).