Functions of Dopaminein the Instrumental Conditioned Reflex
Dopamine neurons are activated by stimuli of both positive and negative modality in accordance with the amount of volitional effort necessary to obtain reward or avoid punishment. The development of an instrumental conditioned reflex begins with the goal of the movement (the external one – the lever or the place in the labyrinth or the internal one – the pose) becomes attractive or repulsive on the basis of the (perhaps dopamine-independent) Pavlovian associative mechanism (“incentive salience attribution”), the driving force of which is the “dopamine drive ”. When performing the instrumental conditioned reflex, from the very beginning, dopamine is excreted in the window between the conditioned signal onset and the movement, where it combines “activation of the central motor system of behavior” [Konorsky, 1970] and modulation of synaptic plasticity for further training. The instrumental movement performed by the animal itself under the influence of the dopamine drive is reinforced by drive reduction.