Sistema de recompensa

Ejemplos de recompensa primarias. En el sentido de las agujas del reloj desde la parte superior izquierda: agua, comida, cuidado parental y sexo.

El sistema de recompensa (el circuito mesocorticolímbico) es un grupo de estructuras neuronales responsables de la prominencia de los incentivos (es decir, "querer"; deseo o ansia de una recompensa y motivación), el aprendizaje asociativo (principalmente el refuerzo positivo y el condicionamiento clásico) y las emociones con valencia positiva, particularmente las que involucran el placer como un componente central (por ejemplo, alegría, euforia y éxtasis). ^[1]​ ^[2]​ La recompensa es la propiedad atractiva y motivadora de un estímulo que induce un comportamiento apetitivo, también conocido como comportamiento de aproximación y comportamiento consumatorio. ^[1]​ Un estímulo gratificante se ha descrito como "cualquier estímulo, objeto, evento, actividad o situación que tenga el potencial de hacer que nos acerquemos a él y lo consumamos; es por definición una recompensa". ^[1]​ En el condicionamiento operante, los estímulos gratificantes funcionan como reforzadores positivos; ^[3]​ sin embargo, la afirmación inversa también es cierta: los reforzadores positivos son gratificantes. ^[3]​ ^[4]​ El sistema de recompensa motiva a los animales a acercarse a estímulos o realizar conductas que aumentan la aptitud física (sexo, alimentos ricos en energía, etc.). La supervivencia de la mayoría de las especies animales depende de maximizar el contacto con estímulos beneficiosos y minimizar el contacto con estímulos dañinos. La cognición de recompensa sirve para aumentar la probabilidad de supervivencia y reproducción al provocar aprendizaje asociativo, provocar un comportamiento de aproximación y consumación y desencadenar emociones con valencia positiva. ^[3]​ Por lo tanto, la recompensa es un mecanismo que evolucionó para ayudar a aumentar la aptitud adaptativa de los animales. ^[5]​ En la adicción a las drogas, ciertas sustancias sobreactivan el circuito de recompensa, lo que conduce a un comportamiento compulsivo de búsqueda de sustancias como resultado de la plasticidad sináptica en el circuito. ^[6]​

Las recompensas primarias son una clase de estímulos gratificantes que facilitan la supervivencia de uno mismo y de la descendencia, e incluyen recompensas homeostáticas (por ejemplo, comida sabrosa) y reproductivas (por ejemplo, contacto sexual e inversión parental). ^[1]​ ^[7]​ Las recompensas intrínsecas son recompensas incondicionadas que son atractivas y motivan el comportamiento porque son inherentemente placenteras. ^[1]​ Las recompensas extrínsecas (por ejemplo, dinero o ver al equipo deportivo favorito ganar un partido) son recompensas condicionadas que son atractivas y motivan el comportamiento, pero no son inherentemente placenteras. ^[1]​ ^[8]​ Las recompensas extrínsecas obtienen su valor motivacional como resultado de una asociación aprendida (es decir, condicionamiento) con recompensas intrínsecas. ^[1]​ Las recompensas extrínsecas también pueden provocar placer (por ejemplo, euforia por ganar mucho dinero en la lotería) después de haber sido condicionadas clásicamente con recompensas intrínsecas. ^[1]​

1. ↑ ^{a b c d e f g h} Schultz, Wolfram (July 2015). «Neuronal Reward and Decision Signals: From Theories to Data». Physiological Reviews 95 (3): 853-951. PMC 4491543. PMID 26109341. doi:10.1152/physrev.00023.2014. 
2. ↑ Berridge KC, Kringelbach ML (May 2015). «Pleasure systems in the brain». Neuron 86 (3): 646-664. PMC 4425246. PMID 25950633. doi:10.1016/j.neuron.2015.02.018. «In the prefrontal cortex, recent evidence indicates that the [orbitofrontal cortex] OFC and insula cortex may each contain their own additional hot spots (D.C. Castro et al., Soc. Neurosci., abstract). In specific subregions of each area, either opioid-stimulating or orexin-stimulating microinjections appear to enhance the number of liking reactions elicited by sweetness, similar to the [nucleus accumbens] NAc and [ventral pallidum] VP hot spots. Successful confirmation of hedonic hot spots in the OFC or insula would be important and possibly relevant to the orbitofrontal mid-anterior site mentioned earlier that especially tracks the subjective pleasure of foods in humans (Georgiadis et al., 2012; Kringelbach, 2005; Kringelbach et al., 2003; Small et al., 2001; Veldhuizen et al., 2010). Finally, in the brainstem, a hindbrain site near the parabrachial nucleus of dorsal pons also appears able to contribute to hedonic gains of function (Söderpalm and Berridge, 2000). A brainstem mechanism for pleasure may seem more surprising than forebrain hot spots to anyone who views the brainstem as merely reflexive, but the pontine parabrachial nucleus contributes to taste, pain, and many visceral sensations from the body and has also been suggested to play an important role in motivation (Wu et al., 2012) and in human emotion (especially related to the somatic marker hypothesis) (Damasio, 2010).» 
3. ↑ ^{a b c} Schultz W (2015). «Neuronal reward and decision signals: from theories to data». Physiological Reviews 95 (3): 853-951. PMC 4491543. PMID 26109341. 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, sexual 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. 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. 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. ... Rewards can also be intrinsic to behavior. They contrast with extrinsic rewards that provide motivation for behavior and constitute the essence of operant behavior in laboratory tests. Intrinsic rewards are activities that are pleasurable on their own and are undertaken for their own sake, without being the means for getting extrinsic rewards. ... Intrinsic rewards are genuine rewards in their own right, as they induce learning, approach, and pleasure, like perfectioning, playing, and enjoying the piano. Although they can serve to condition higher order rewards, they are not conditioned, higher order rewards, as attaining their reward properties does not require pairing with an unconditioned reward. ... These emotions are also called liking (for pleasure) and wanting (for desire) in addiction research and strongly support the learning and approach generating functions of reward.» 
4. ↑ Guo, Rong; Böhmer, Wendelin; Hebart, Martin; Chien, Samson; Sommer, Tobias; Obermayer, Klaus; Gläscher, Jan (14 de diciembre de 2016). «Interaction of Instrumental and Goal-Directed Learning Modulates Prediction Error Representations in the Ventral Striatum». The Journal of Neuroscience (Society for Neuroscience) 36 (50): 12650-12660. ISSN 0270-6474. PMC 6705659. PMID 27974615. doi:10.1523/jneurosci.1677-16.2016. 
5. ↑ Kolb, Bryan; Whishaw, Ian Q. (2001). An Introduction to Brain and Behavior (1st edición). New York: Worth. pp. 438–441. ISBN 9780716751694. 
6. ↑ Brain & Behavior Research Foundation (March 13, 2019). «The Biology of Addiction». YouTube. 
7. ↑ «Dopamine Involved In Aggression». Medical News Today. 15 January 2008. Archivado desde el original el September 23, 2010. Consultado el 14 November 2010. 
8. ↑ Duarte, Isabel C.; Afonso, Sónia; Jorge, Helena; Cayolla, Ricardo; Ferreira, Carlos; Castelo-Branco, Miguel (1 de mayo de 2017). «Tribal love: the neural correlates of passionate engagement in football fans». Social Cognitive and Affective Neuroscience 12 (5): 718-728. PMC 5460049. PMID 28338882. doi:10.1093/scan/nsx003.