Dopamine and inverse incentive learning explains that dopamine determines an incentive–value continuum. Novel and intense stimuli innately produce rapid dopamine neurons activation followed by inhibition. The repeated presentation of novel stimuli leads to a loss of this effect. Aversive stimuli, biologically important by definition, often deactivate dopamine neurons and may produce inverse incentive learning, leading to conditioned inverse incentive stimuli with decreased ability to elicit approach and other responses. The offset of aversion may increase the firing of dopamine neurons producing incentive learning about safety-related stimuli. Habituation to stimuli enhances their ability to produce inverse incentive learning, suggesting that inverse incentive learning may occur during habituation. In the end, there may be no “neutral” stimuli, only stimuli that lie on a continuum of incentive value from strong conditioned incentive stimuli to strong conditioned inverse incentive stimuli with most of the things we encounter in day-to-day life falling in between.
Catecholaminergic mechanisms underlying neurohypophysial hormone responses to unconditioned or conditioned aversive stimuli in rats
