Mesolimbic Dopamine and the Regulation of Motivated Behavior

Abstract

It has been known for some time that nucleus accumbens dopamine (DA) is involved in aspects of motivation , but theoretical approaches to understanding the functions of DA have continued to evolve based upon emerging data and novel concepts. Although it has become traditional to label DA neurons as "reward" neurons, the actual findings are more complicated than that, because they indicate that DA neurons can respond to a variety of motivationally significant stimuli. Moreover, it is important to distinguish between aspects of motivation that are differentially affected by dopaminergic manipulations. Studies that involve nucleus accumbens DA antagonism or depletion indicate that accumbens DA does not mediate primary food motivation or appetite. Nevertheless, DA is involved in appetitive and aversive motivational processes including behavioral activation , exertion of effort, sustained task engagement, and Pavlovian-to-instrumental transfer. Interference with accumbens DA transmission affects instrumental behavior in a manner that interacts with the response requirements of the task and also shifts effort-related choice behavior, biasing animals toward low-effort alternatives. Dysfunctions of mesolimbic DA may contribute to motivational symptoms seen in various psychopathologies, including depression , schizophrenia, parkinsonism, and other disorders.

Neural substrates underlying effort, time, and risk-based decision making in motivated behavior

“…The NAcc core appears to be critical for effortful choice behavior, as it is was shown to be involved in all three tasks. The GABAergic connection between the NAcc Core and the VP has been shown to be important in the EBCT (Farrar et al, 2008; Font et al, 2008; Mingote et al, 2008; John D. Salamone et al, 2015), but to our knowledge has yet to be examined in other effort based choice paradigms, but such studies may be fruitful for future investigators as the VP is thought to be implicated in motivational processes (McGinty et al, 2011). …”

Motivated state control in larval zebrafish: behavioral paradigms and anatomical substrates

“…Distinct motivated states equip animals to cope with different challenges. Nevertheless, studies on motivated states have distinguished ‘activational’ and ‘directional’ components (Salamone, 1988; Bailey et al, 2015; Salamone et al, 2015). The directional component relates to goal-directed behaviors whereby sensory processing and motor programs are tuned to advance homeostatic needs or prepare for anticipated challenges.…”

Surprise! Dopamine signals mix action, value and error

“…However, how dopamine operates across these domains remains poorly understood. On one hand, a large amount of literature focuses on the role of dopamine in motivation to exert physical effort to obtain a reward 1 or the incentive-motivating properties of stimuli that drive 'wanting' 2 . On the other hand, an influential theory proposes that phasic changes in dopaminergic signals reflect reward prediction errors (RPEs), or outcomes that are better or worse than expected 3 ; these are used to potentiate corticostriatal synapses, thereby implementing a form of reinforcement learning.…”