Wikipédia

Saillance motivationnelle

La saillance motivationnelle est un processus cognitif et une forme d'attention qui motive ou propulse le comportement d'un individu vers ou loin d'un objet particulier, d'un événement ou d'un résultat perçu[1]. La saillance motivationnelle régule l'intensité des comportements qui facilitent la réalisation d'un objectif particulier, la quantité de temps et d'énergie qu'un individu est prêt à consacrer pour atteindre un objectif particulier, et la quantité de risque qu'un individu est prêt à accepter tout en travaillant pour atteindre un objectif particulier.

La saillance motivationnelle est composée de deux processus qui se définissent par leurs effets attractifs ou aversifs sur le comportement d'un individu par rapport à un stimulus particulier : la saillance incitative et la saillance aversive[1]. La saillance incitative est la forme attractive de saillance motivationnelle qui provoque un comportement d'approche et est associée à un renforcement opérant, à des résultats souhaitables et à des stimuli agréables[2],[3]. La saillance aversive est la forme aversive de saillance motivationnelle qui provoque un comportement d'évitement et est associée à une punition opérante, à des résultats indésirables et à des stimuli désagréables[4].

Saillance incitative modifier

La saillance incitative est un processus cognitif qui confère à un stimulus gratifiant un attribut «désir» ou «envie», qui comprend une composante motivationnelle[1],[2]. La récompense est la propriété attractive et motivante d'un stimulus qui induit un comportement appétitif - également connu sous le nom de comportement d'approche - et un comportement de consommation[3]. Le «désir» de la saillance incitative diffère du «goût» (ou plaisir) dans le sens où le goût est le plaisir qui est immédiatement obtenu de l'acquisition ou de la consommation d'un stimulus gratifiant[5] ; le «désir» de saillance incitative sert à la qualité d'«aimant motivationnel» à un stimulus gratifiant qui en fait un objectif souhaitable et attrayant, le transformant d'une simple expérience sensorielle en quelque chose qui attire l'attention, induit une approche, et provoque la recherche[6].

La saillance incitative est régulée par un certain nombre de structures cérébrales, mais elle est attribuée aux stimuli par une région du striatum ventral appelée la partie ventrale du noyau accumbens[1],[2],[6]. La saillance incitative est principalement régulée par la neurotransmission de la dopamine dans la projection mésocorticolimbique, mais l'activité d'autres voies dopaminergiques et de centres du plaisir (par exemple, le pallidum ventral) modulent également la saillance incitative[7],[5],[6],[2].

Signification clinique modifier

Dépendance modifier

L'attribution de la saillance incitative aux stimuli est dérégulée dans la dépendance[1],[6],[5]. Les drogues addictives sont intrinsèquement gratifiantes (c.-à-d. agréables) et fonctionnent donc comme les principaux renforçateurs positifs de la poursuite de la consommation de drogues qui ont une saillance incitative[3],[7]. Au cours du développement d'une dépendance, l'association répétée de stimuli autrement neutres et même non gratifiants à la consommation de drogue déclenche un processus d'apprentissage associatif qui fait que ces stimuli auparavant neutres agissent comme des renforçateurs positifs conditionnés de la toxicomanie (c'est-à-dire que ces stimuli commencent à fonctionner comme des signaux de drogue ). En tant que renforçateurs positifs conditionnés de la consommation de drogues, ces stimuli auparavant neutres se voient attribuer une saillance incitative (qui se manifeste par une envie) - parfois à des niveaux pathologiquement élevés en raison de la sensibilisation aux récompenses   - qui peut être transféré au renforçateur primaire (par exemple, l'utilisation d'une drogue provoquant une dépendance) avec lequel il a été initialement associé. Ainsi, si un individu reste abstinent à consommer de la drogue pendant un certain temps et rencontre l'un de ces indices, une envie de drogue associée peut réapparaître. Par exemple, les agences de lutte contre la drogue utilisaient auparavant des affiches avec des images d'accessoires de drogue pour montrer les dangers de la consommation de drogues. Cependant, de telles affiches ne sont plus utilisées en raison des effets de la saillance incitative en provoquant une rechute à la vue des stimuli illustrés dans les affiches. [réf. nécessaire]

Dans la dépendance, le «goût» (plaisir ou valeur hédonique ) d'une drogue ou d'un autre stimulus se dissocie du «désir» (c'est-à-dire le désir ou l'envie) en raison de la sensibilisation de la saillance incitative[8]. En fait, si la saillance incitative associée à la prise de drogue s'amplifie pathologiquement, l'utilisateur peut vouloir de plus en plus le médicament tout en l'aimant de moins en moins à mesure que la tolérance se développe aux effets agréables du médicament[5].

Neuropsychopharmacologie modifier

Psychostimulants dopaminergiques modifier

L'amphétamine améliore la saillance des tâches (motivation à effectuer une tâche) et augmente l'excitation (éveil), favorisant à son tour un comportement axé sur les objectifs[9],[10]. Les effets renforçateurs et motivants favorisant la saillance de l'amphétamine sont principalement dus à une activité dopaminergique accrue dans la voie mésolimbique[11].

Voir également modifier

Références modifier

  1. ↑ a b c d et e « Prefrontal/accumbal catecholamine system processes high motivational salience », Front. Behav. Neurosci., vol. 6,‎ , p. 31 (PMID 22754514, PMCID 3384081, DOI 10.3389/fnbeh.2012.00031) :

    « Motivational salience regulates the strength of goal seeking, the amount of risk taken, and the energy invested from mild to extreme. ... Motivation can be conceptually described as a continuum along which stimuli can either reinforce or punish responses to other stimuli. Behaviorally, stimuli that reinforce are called rewarding and those that punish aversive (Skinner, 1953). Reward and aversion describe the impact a stimulus has on behavior, and provided of motivational properties, thus able to induce attribution of motivational salience. ... Attribution of motivational salience is related to the salience of an UCS (Dallman et al., 2003; Pecina et al., 2006). Thus, the more salient an UCS the more likely a neutral (to-be-conditioned) stimulus will be associated with it through motivational salience attribution. Prior experience is a major determinant of the motivational impact of any given stimulus (Borsook et al., 2007) and emotional arousal induced by motivational stimuli increases the attention given to stimuli influencing both the initial perceptual encoding and the consolidation process (Anderson et al., 2006; McGaugh, 2006). »
  2. ↑ a b c et d Molecular Neuropharmacology : A Foundation for Clinical Neuroscience, New York, , 2e éd., 147–148, 367, 376 (ISBN 978-0-07-148127-4)

    « VTA DA neurons play a critical role in motivation, reward-related behavior (Chapter 15), attention, and multiple forms of memory. This organization of the DA system, wide projection from a limited number of cell bodies, permits coordinated responses to potent new rewards. Thus, acting in diverse terminal fields, dopamine confers motivational salience (“wanting”) on the reward itself or associated cues (nucleus accumbens shell region), updates the value placed on different goals in light of this new experience (orbital prefrontal cortex), helps consolidate multiple forms of memory (amygdala and hippocampus), and encodes new motor programs that will facilitate obtaining this reward in the future (nucleus accumbens core region and dorsal striatum). In this example, dopamine modulates the processing of sensorimotor information in diverse neural circuits to maximize the ability of the organism to obtain future rewards. ...
    The brain reward circuitry that is targeted by addictive drugs normally mediates the pleasure and strengthening of behaviors associated with natural reinforcers, such as food, water, and sexual contact. Dopamine neurons in the VTA are activated by food and water, and dopamine release in the NAc is stimulated by the presence of natural reinforcers, such as food, water, or a sexual partner. ...
    The NAc and VTA are central components of the circuitry underlying reward and memory of reward. As previously mentioned, the activity of dopaminergic neurons in the VTA appears to be linked to reward prediction. The NAc is involved in learning associated with reinforcement and the modulation of motoric responses to stimuli that satisfy internal homeostatic needs. The shell of the NAc appears to be particularly important to initial drug actions within reward circuitry; addictive drugs appear to have a greater effect on dopamine release in the shell than in the core of the NAc. »

  3. ↑ a b et c « Neuronal reward and decision signals: from theories to data », Physiological Reviews, vol. 95, no 3,‎ , p. 853–951 (PMID 26109341, PMCID 4491543, DOI 10.1152/physrev.00023.2014) :

    « Rewards in operant conditioning are positive reinforcers. ... Operant behavior gives a good definition for rewards. Anything that makes an individual come back for more is a positive reinforcer and therefore a reward. Although it provides a good definition, positive reinforcement is only one of several reward functions. ... Rewards are attractive. They are motivating and make us exert an effort. ... Rewards induce approach behavior, also called appetitive or preparatory behavior, and consummatory behavior. ... Thus any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward. ... Rewarding stimuli, objects, events, situations, and activities consist of several major components. First, rewards have basic sensory components (visual, auditory, somatosensory, gustatory, and olfactory) ... Second, rewards are salient and thus elicit attention, which are manifested as orienting responses (FIGURE 1, middle). The salience of rewards derives from three principal factors, namely, their physical intensity and impact (physical salience), their novelty and surprise (novelty/surprise salience), and their general motivational impact shared with punishers (motivational salience). A separate form not included in this scheme, incentive salience, primarily addresses dopamine function in addiction and refers only to approach behavior (as opposed to learning) ... Third, rewards have a value component that determines the positively motivating effects of rewards and is not contained in, nor explained by, the sensory and attentional components (FIGURE 1, right). This component reflects behavioral preferences and thus is subjective and only partially determined by physical parameters. Only this component constitutes what we understand as a reward. It mediates the specific behavioral reinforcing, approach generating, and emotional effects of rewards that are crucial for the organism's survival and reproduction, whereas all other components are only supportive of these functions. ... These emotions are also called liking (for pleasure) and wanting (for desire) in addiction research (471) and strongly support the learning and approach generating functions of reward. »
  4. ↑ Koob GF, Moal ML, Neurobiology of Addiction, Amsterdam, Elsevier/Academic Press, , 504 p. (ISBN 978-0-08-049737-2, lire en ligne), p. 415
  5. ↑ a b c et d « Pleasure systems in the brain », Neuron, vol. 86, no 3,‎ , p. 646–664 (PMID 25950633, PMCID 4425246, DOI 10.1016/j.neuron.2015.02.018) :

    « An important goal in future for addiction neuroscience is to understand how intense motivation becomes narrowly focused on a particular target. Addiction has been suggested to be partly due to excessive incentive salience produced by sensitized or hyper-reactive dopamine systems that produce intense ‘wanting’ (Robinson and Berridge, 1993). But why one target becomes more ‘wanted’ than all others has not been fully explained. In addicts or agonist-stimulated patients, the repetition of dopamine-stimulation of incentive salience becomes attributed to particular individualized pursuits, such as taking the addictive drug or the particular compulsions. In Pavlovian reward situations, some cues for reward become more ‘wanted’ more than others as powerful motivational magnets, in ways that differ across individuals (Robinson et al., 2014b; Saunders and Robinson, 2013). ... However, hedonic effects might well change over time. As a drug was taken repeatedly, mesolimbic dopaminergic sensitization could consequently occur in susceptible individuals to amplify ‘wanting’ (Leyton and Vezina, 2013; Lodge and Grace, 2011; Wolf and Ferrario, 2010), even if opioid hedonic mechanisms underwent down-regulation due to continual drug stimulation, producing ‘liking’ tolerance. Incentive-sensitization would produce addiction, by selectively magnifying cue-triggered ‘wanting’ to take the drug again, and so powerfully cause motivation even if the drug became less pleasant (Robinson and Berridge, 1993). »
  6. ↑ a b c et d « From prediction error to incentive salience: mesolimbic computation of reward motivation », Eur. J. Neurosci., vol. 35, no 7,‎ , p. 1124–1143 (PMID 22487042, PMCID 3325516, DOI 10.1111/j.1460-9568.2012.07990.x) :

    « Here I discuss how mesocorticolimbic mechanisms generate the motivation component of incentive salience. Incentive salience takes Pavlovian learning and memory as one input and as an equally important input takes neurobiological state factors (e.g. drug states, appetite states, satiety states) that can vary independently of learning. Neurobiological state changes can produce unlearned fluctuations or even reversals in the ability of a previously learned reward cue to trigger motivation. Such fluctuations in cue-triggered motivation can dramatically depart from all previously learned values about the associated reward outcome. ... Associative learning and prediction are important contributors to motivation for rewards. Learning gives incentive value to arbitrary cues such as a Pavlovian conditioned stimulus (CS) that is associated with a reward (unconditioned stimulus or UCS). Learned cues for reward are often potent triggers of desires. For example, learned cues can trigger normal appetites in everyone, and can sometimes trigger compulsive urges and relapse in addicts. ... A brief CS encounter (or brief UCS encounter) often primes a pulse of elevated motivation to obtain and consume more reward UCS. This is a signature feature of incentive salience. ... When a Pavlovian CS+ is attributed with incentive salience it not only triggers ‘wanting’ for its UCS, but often the cue itself becomes highly attractive – even to an irrational degree. This cue attraction is another signature feature of incentive salience. ... An attractive CS often elicits behavioral motivated approach, and sometimes an individual may even attempt to ‘consume’ the CS somewhat as its UCS (e.g., eat, drink, smoke, have sex with, take as drug). ‘Wanting’ of a CS can turn also turn the formerly neutral stimulus into an instrumental conditioned reinforcer, so that an individual will work to obtain the cue (however, there exist alternative psychological mechanisms for conditioned reinforcement too). ... Two recognizable features of incentive salience are often visible that can be used in neuroscience experiments: (i) UCS-directed 'wanting' – CS-triggered pulses of intensified 'wanting' for the UCS reward; and (ii) CS-directed 'wanting' – motivated attraction to the Pavlovian cue, which makes the arbitrary CS stimulus into a motivational magnet. »
  7. ↑ a et b « Reinforcement principles for addiction medicine; from recreational drug use to psychiatric disorder », Prog. Brain Res., progress in Brain Research, vol. 223,‎ , p. 63–76 (ISBN 9780444635457, PMID 26806771, DOI 10.1016/bs.pbr.2015.07.005) :

    « Abused substances (ranging from alcohol to psychostimulants) are initially ingested at regular occasions according to their positive reinforcing properties. Importantly, repeated exposure to rewarding substances sets off a chain of secondary reinforcing events, whereby cues and contexts associated with drug use may themselves become reinforcing and thereby contribute to the continued use and possible abuse of the substance(s) of choice. ...
    An important dimension of reinforcement highly relevant to the addiction process (and particularly relapse) is secondary reinforcement (Stewart, 1992). Secondary reinforcers (in many cases also considered conditioned reinforcers) likely drive the majority of reinforcement processes in humans. In the specific case of drug [addiction], cues and contexts that are intimately and repeatedly associated with drug use will often themselves become reinforcing ... A fundamental piece of Robinson and Berridge's incentive-sensitization theory of addiction posits that the incentive value or attractive nature of such secondary reinforcement processes, in addition to the primary reinforcers themselves, may persist and even become sensitized over time in league with the development of drug addiction (Robinson and Berridge, 1993). ...
    Negative reinforcement is a special condition associated with a strengthening of behavioral responses that terminate some ongoing (presumably aversive) stimulus. In this case we can define a negative reinforcer as a motivational stimulus that strengthens such an “escape” response. Historically, in relation to drug addiction, this phenomenon has been consistently observed in humans whereby drugs of abuse are self-administered to quench a motivational need in the state of withdrawal (Wikler, 1952). »
  8. ↑ Berridge, K.C., Robinson, T.E. What is the role of dopamine in reward: hedonic impact, reward learning, or incentive salience? Brain Res Brain Res Rev. 1998 Dec; 28(3):309–69.
  9. ↑ Molecular Neuropharmacology : A Foundation for Clinical Neuroscience, New York, USA, , 2e éd., 516 p. (ISBN 978-0-07-148127-4), « Chapter 10: Neural and Neuroendocrine Control of the Internal Milieu », p. 266

    « Dopamine acts in the nucleus accumbens to attach motivational significance to stimuli associated with reward. »

  10. ↑ « Psychostimulants and cognition: a continuum of behavioral and cognitive activation », Pharmacol. Rev., vol. 66, no 1,‎ , p. 193–221 (PMID 24344115, PMCID 3880463, DOI 10.1124/pr.112.007054)
  11. ↑ Molecular Neuropharmacology : A Foundation for Clinical Neuroscience, New York, USA, , 2e éd., 318, 321 (ISBN 978-0-07-148127-4), « Chapter 13: Higher Cognitive Function and Behavioral Control »

    « Therapeutic (relatively low) doses of psychostimulants, such as methylphenidate and amphetamine, improve performance on working memory tasks both in normal subjects and those with ADHD. ... stimulants act not only on working memory function, but also on general levels of arousal and, within the nucleus accumbens, improve the saliency of tasks. Thus, stimulants improve performance on effortful but tedious tasks ... through indirect stimulation of dopamine and norepinephrine receptors. ...
    Beyond these general permissive effects, dopamine (acting via D1 receptors) and norepinephrine (acting at several receptors) can, at optimal levels, enhance working memory and aspects of attention. »

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