The Neurobiology of Activational Aspects of Motivation: Exertion of Effort, Effort-Based Decision Making, and the Role of Dopamine

Abstract

Motivational processes are complex and multifaceted, with both directional and activational aspects. Behavioral activation and exertion of effort are functions that enable organisms to overcome obstacles separating them from significant outcomes. In a complex environment, organisms make cost/benefit decisions, assessing work-related response costs and reinforcer preference. Animal studies have challenged the general idea that dopamine (DA) is best viewed as the reward transmitter and instead have illustrated the involvement of DA in activational and effort-related processes. Mesocorticolimbic DA is a key component of the effort-related motivational circuitry that includes multiple neurotransmitters and brain areas. Human studies have identified brain areas and transmitter systems involved in effort-based decision making and characterized the reduced selection of high-effort activities associated with motivational symptoms of depression and schizophrenia. Animal and human research on the neurochemistry of behavioral activation and effort-related processes makes an important conceptual contribution by illustrating the dissociable nature of distinct aspects of motivation. Expected final online publication date for the Annual Review of Psychology, Volume 75 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Dopamine, activation of ingestion and evaluation of response efficacy: a focus on the within-session time-course of licking burst number

“…The contingent value of the reward might be regarded as the computational term which provides the basis to determine the level of activation of the reward-directed response, hence the cost of the response – in terms of effort – which is congruous in the given physiological, psychological and environmental condition (D’Aquila 2010 ). This account is consistent with the theoretical view which regards dopamine’s role in terms of cost-benefit analysis based choice and response effort allocation (Salamone et al 2005 , 2007 , 2009 ; Salamone and Correa 2024 ; Treadway and Salamone 2022 ). However, the experimental measures provided by the study of licking microstructure are not particularly apt to be interpreted in terms of cost-benefit analysis, since the effort demand of licking behaviour is very low.…”

“…This process would consist in the transformation of the neural representation of a reward-related stimulus into a motivationally potent incentive, thus acting as a trigger for the activation of the appropriate reward-directed response (Berridge 2007 ; Nguyen et al 2021 ; Olney et al 2018 ; Warlow and Berridge 2021 ). Moreover, rats with dopamine depletion in the nucleus accumbens tend to shift their responses toward less effortful choices but still maintain the ability to choose a larger reward when no additional effort is required, suggesting a role for dopamine in response effort allocation but not in the ability to assess the reward-value (Salamone 2007 ; Salamone et al 2005 , 2007 ; Salamone and Correa 2024 ; Treadway and Salamone 2022 ). Other theoretical perspectives posit an involvement of dopamine in cost-benefit computational mechanisms (Baldo and Kelley 2007 ; Cannon and Palmiter 2003 ; Hori et al 2021 ; Kroemer et al 2016 ; Niv et al 2005 ; Phillips et al 2007 ).…”

Task goals shape the relationship between decision and movement speed

“…As such, this structure could be at the source of a signal invigorating behavior as a whole to maximize reward rate, as hypothesized in several studies of the last decade (Carsten et al, 2023; Cisek & Thura, 2022; Thura, 2020; Thura et al, 2022; Thura & Cisek, 2017). Reward-sensitivity of the dopaminergic system has been extensively studied in the past (Berridge & Robinson, 2016; Salamone & Correa, 2024; Schultz et al, 2017; Weinstein, 2023) Consistently, dopamine seems strongly implicated in the control of decision speed and movement vigor (Bourgeois et al, 2016; Coddington & Dudman, 2019; Niv, 2007; Pietro Mazzoni et al, 2007). Interestingly, it is believed that it amplifies motor gain (Park et al, 2020; Yttri & Dudman, 2018), which seems to rely, at least in part, on inhibitory influences increasing the signal-to-noise ratio in motor neural activity (Duque et al, 2017; Greenhouse, 2022; Vassiliadis et al, 2020; Wilhelm et al, 2022).…”

Methylphenidate, but not citalopram, decreases impulsive choice in rats performing a temporal discounting task

“…Our results are consistent with prior studies showing that global 5-HT depletion does not affect delay discounting ( 71 ). Likewise, 5-HT depletion does not alter effort-based choice and citalopram cannot rescue motivational impairments ( 33 , 55 ). A larger body of evidence suggests serotonergic agents affect action impulsivity ( 3 , 54 , 72 – 76 ).…”

“…Cortico-striatal structures are regulated by dopaminergic and serotonergic systems which affect impulsive choice ( 1 , 7 , 15 , 18 , 29 – 31 ). Mesolimbic dopamine, originating from the ventral tegmental area terminating in ventral striatum, regulates behavioral activation, motivation, and reinforcing properties ( 12 , 32 , 33 ). Dopamine (and by proxy drugs that increase dopamine) generally reduce choice impulsivity on temporal discounting tasks ( 12 , 34 ).…”