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Kent Berridge | |
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| Born | 1957 (age 66–67) |
| Alma mater | University of California, Davis (BS) University of Pennsylvania (PhD) |
| Scientific career | |
| Fields | Biopsychology Neuroscience |
| Institutions | University of Michigan |
Kent C. Berridge [1] (born 1957) is an American academic, currently working as a professor of psychology (biopsychology) and neuroscience at the University of Michigan. Berridge was a joint winner of the 2018 Grawemeyer Award for Psychology. [2]
Berridge was born in 1957. [3] Berridge earned a Bachelor of Science from the University of California, Davis in 1979, followed by a PhD from the University of Pennsylvania in 1983. [4]
Berridge conducts research relating to brain systems of motivation, affect, reward “liking”, reward “wanting”, emotion, fear, pleasure, drug addiction, eating disorders, and decision utility. He also studies natural syntactical chains of behavior (e.g. grooming; taste response patterns) in animals with colleague Dr. J. Wayne Aldridge. With Dr. Piotr Winkielman, he has investigated the issue of unconscious emotion in humans.
Berridge is known for his work on the brain systems for pleasure (“liking”). [5] Using an assay for “liking” called Taste Reactivity Analysis developed by taste researchers, Berridge measures facial palatability responses to tastes, which are similar between rodents, primates and humans. [6] When something enjoyably sweet is tasted, characteristic licking responses occur. When something aversively bitter is tasted, gaping and head shaking occur. Berridge has helped identify "hedonic hotspots" in the brain, such as the nucleus accumbens and ventral pallidum, where opioid, endocannabinoid, and GABA neurotransmission coordinate the “liking” of tastes. Berridge postulates that these hedonic hotspots may be crucial for how the brain produces the hedonic pleasurable feelings common to delicious food, sex, drugs, and other rewards (a role previously thought to be played mostly by brain dopamine systems).
Berridge and colleague Dr. Terry Robinson have formulated a contemporary theory of addiction called the Incentive Sensitization Theory of Addiction. [7] According to this theory, drug addiction develops from a sensitization of the mesolimbic dopamine system. Dopamine normally functions to attribute incentive salience to stimuli associated with rewards like food and sex, and triggers reward “wanting”. Drugs hijack this “wanting” system. Following repeated use of drugs, the dopamine system becomes hyper-responsive and drug cues become hyper-salient. This means drug cues are nearly impossible for addicts to ignore, and when they are encountered they can lead to intense cravings and/or relapse. This sensitized cue-triggered drug 'wanting' can persist for years after an addict quits drugs, and long after drug withdrawal has ceased. This fact may account for the tendency of former addicts to relapse to drug use after quitting, sometimes even after many years of abstinence.
Berridge and Robinson helped redefine the role of mesolimbic dopamine in the brain, [8] which had previously been viewed as a pleasure neurotransmitter. Dopamine is no longer widely regarded as a pleasure transmitter. Instead, dopamine is thought to mediate reward, that is, to attribute incentive salience to reward-associated stimuli.
Dopamine is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% of the catecholamine content in the brain. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical, L-DOPA, which is synthesized in the brain and kidneys. Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons to send signals to other nerve cells. Neurotransmitters are synthesized in specific regions of the brain, but affect many regions systemically. The brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, and many addictive drugs increase dopamine release or block its reuptake into neurons following release. Other brain dopamine pathways are involved in motor control and in controlling the release of various hormones. These pathways and cell groups form a dopamine system which is neuromodulatory.
Operant conditioning, also called instrumental conditioning, is a learning process where voluntary behaviors are modified by association with the addition of reward or aversive stimuli. The frequency or duration of the behavior may increase through reinforcement or decrease through punishment or extinction.
Pleasure is experience that feels good, that involves the enjoyment of something. It contrasts with pain or suffering, which are forms of feeling bad. It is closely related to value, desire and action: humans and other conscious animals find pleasure enjoyable, positive or worthy of seeking. A great variety of activities may be experienced as pleasurable, like eating, having sex, listening to music or playing games. Pleasure is part of various other mental states such as ecstasy, euphoria and flow. Happiness and well-being are closely related to pleasure but not identical with it. There is no general agreement as to whether pleasure should be understood as a sensation, a quality of experiences, an attitude to experiences or otherwise. Pleasure plays a central role in the family of philosophical theories known as hedonism.
In behavioral psychology, reinforcement refers to consequences that increase the likelihood of an organism's future behavior, typically in the presence of a particular antecedent stimulus. For example, a rat can be trained to push a lever to receive food whenever a light is turned on. In this example, the light is the antecedent stimulus, the lever pushing is the operant behavior, and the food is the reinforcer. Likewise, a student that receives attention and praise when answering a teacher's question will be more likely to answer future questions in class. The teacher's question is the antecedent, the student's response is the behavior, and the praise and attention are the reinforcements.
The mesolimbic pathway, sometimes referred to as the reward pathway, is a dopaminergic pathway in the brain. The pathway connects the ventral tegmental area in the midbrain to the ventral striatum of the basal ganglia in the forebrain. The ventral striatum includes the nucleus accumbens and the olfactory tubercle.
The nucleus accumbens is a region in the basal forebrain rostral to the preoptic area of the hypothalamus. The nucleus accumbens and the olfactory tubercle collectively form the ventral striatum. The ventral striatum and dorsal striatum collectively form the striatum, which is the main component of the basal ganglia. The dopaminergic neurons of the mesolimbic pathway project onto the GABAergic medium spiny neurons of the nucleus accumbens and olfactory tubercle. Each cerebral hemisphere has its own nucleus accumbens, which can be divided into two structures: the nucleus accumbens core and the nucleus accumbens shell. These substructures have different morphology and functions.
Dopaminergic pathways in the human brain are involved in both physiological and behavioral processes including movement, cognition, executive functions, reward, motivation, and neuroendocrine control. Each pathway is a set of projection neurons, consisting of individual dopaminergic neurons.
Dopamine receptors are a class of G protein-coupled receptors that are prominent in the vertebrate central nervous system (CNS). Dopamine receptors activate different effectors through not only G-protein coupling, but also signaling through different protein interactions. The neurotransmitter dopamine is the primary endogenous ligand for dopamine receptors.
Motivational salience is a cognitive process and a form of attention that motivates or propels an individual's behavior towards or away from a particular object, perceived event or outcome. Motivational salience regulates the intensity of behaviors that facilitate the attainment of a particular goal, the amount of time and energy that an individual is willing to expend to attain a particular goal, and the amount of risk that an individual is willing to accept while working to attain a particular goal.
Sensitization is a non-associative learning process in which repeated administration of a stimulus results in the progressive amplification of a response. Sensitization often is characterized by an enhancement of response to a whole class of stimuli in addition to the one that is repeated. For example, repetition of a painful stimulus may make one more responsive to a loud noise.
The reward system is a group of neural structures responsible for incentive salience, associative learning, and positively-valenced emotions, particularly ones involving pleasure as a core component. Reward is the attractive and motivational property of a stimulus that induces appetitive behavior, also known as approach behavior, and consummatory behavior. A rewarding stimulus has been described as "any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward". In operant conditioning, rewarding stimuli function as positive reinforcers; however, the converse statement also holds true: positive reinforcers are rewarding.
Palatability is the hedonic reward provided by foods or fluids that are agreeable to the "palate", which often varies relative to the homeostatic satisfaction of nutritional and/or water needs. The palatability of a food or fluid, unlike its flavor or taste, varies with the state of an individual: it is lower after consumption and higher when deprived. It has increasingly been appreciated that this can create a hunger that is independent of homeostatic needs.
Desires are states of mind that are expressed by terms like "wanting", "wishing", "longing" or "craving". A great variety of features is commonly associated with desires. They are seen as propositional attitudes towards conceivable states of affairs. They aim to change the world by representing how the world should be, unlike beliefs, which aim to represent how the world actually is. Desires are closely related to agency: they motivate the agent to realize them. For this to be possible, a desire has to be combined with a belief about which action would realize it. Desires present their objects in a favorable light, as something that appears to be good. Their fulfillment is normally experienced as pleasurable in contrast to the negative experience of failing to do so. Conscious desires are usually accompanied by some form of emotional response. While many researchers roughly agree on these general features, there is significant disagreement about how to define desires, i.e. which of these features are essential and which ones are merely accidental. Action-based theories define desires as structures that incline us toward actions. Pleasure-based theories focus on the tendency of desires to cause pleasure when fulfilled. Value-based theories identify desires with attitudes toward values, like judging or having an appearance that something is good.
The ventral pallidum (VP) is a structure within the basal ganglia of the brain. It is an output nucleus whose fibres project to thalamic nuclei, such as the ventral anterior nucleus, the ventral lateral nucleus, and the medial dorsal nucleus. The VP is a core component of the reward system which forms part of the limbic loop of the basal ganglia, a pathway involved in the regulation of motivational salience, behavior, and emotions. It is involved in addiction.
Addiction is a neuropsychological disorder characterized by a persistent and intense urge to use a drug or engage in a behaviour that produces natural reward, despite substantial harm and other negative consequences. Repetitive drug use often alters brain function in ways that perpetuate craving, and weakens self-control. This phenomenon – drugs reshaping brain function – has led to an understanding of addiction as a brain disorder with a complex variety of psychosocial as well as neurobiological factors that are implicated in addiction's development. Classic signs of addiction include compulsive engagement in rewarding stimuli, preoccupation with substances or behavior, and continued use despite negative consequences. Habits and patterns associated with addiction are typically characterized by immediate gratification, coupled with delayed deleterious effects.
Addiction is a state characterized by compulsive engagement in rewarding stimuli, despite adverse consequences. The process of developing an addiction occurs through instrumental learning, which is otherwise known as operant conditioning.
Hedonic hunger or hedonic hyperphagia is the "drive to eat to obtain pleasure in the absence of an energy deficit". Particular foods may have a high "hedonic rating" or individuals may have increased susceptibility to environmental food cues. Weight loss programs may aim to control or to compensate for hedonic hunger. Therapeutic interventions may influence hedonic eating behavior.
Pavlovian-instrumental transfer (PIT) is a psychological phenomenon that occurs when a conditioned stimulus that has been associated with rewarding or aversive stimuli via classical conditioning alters motivational salience and operant behavior. Two distinct forms of Pavlovian-instrumental transfer have been identified in humans and other animals – specific PIT and general PIT – with unique neural substrates mediating each type. In relation to rewarding stimuli, specific PIT occurs when a CS is associated with a specific rewarding stimulus through classical conditioning and subsequent exposure to the CS enhances an operant response that is directed toward the same reward with which it was paired. General PIT occurs when a CS is paired with one reward and it enhances an operant response that is directed toward a different rewarding stimulus.
Drug liking is a measure of the pleasurable (hedonic) experience when a person consumes drugs. It is commonly used to study the misuse liability of drugs. Drug liking is often measured using unipolar and bipolar visual analogue scales (VAS), such as the Drug Liking VAS, the High VAS, the Take Drug Again (TDA) VAS, and the Overall Drug Liking (ODL) VAS. There is a dissociation of drug liking from drug wanting. Drugs that increase scores on drug-liking measures include amphetamines, cocaine, methylphenidate, MDMA, opioids, benzodiazepines, Z-drugs, barbiturates, alcohol, nicotine, and caffeine (limitedly), among others.
Terry Earl Robinson is a biopsychologist and neuroscientist, and the Elliot S. Valenstein Distinguished University Professor of Psychology & Neuroscience at The University of Michigan.
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