Pleasure center
Encyclopedia
Pleasure center is the general term used for the brain regions involved in pleasure
. Discoveries made in the 1950s initially suggested that rodents could not stop electrically stimulating parts of their brain, mainly the nucleus accumbens
, which was theorized to produce great pleasure
. Further investigations revealed that the septum pellucidium and the hypothalamus
can also be targets for self-stimulation. Yet, more recent research has shown that such ‘pleasure’ electrodes do not, in fact, lead to pleasure but only a form of ‘wanting’ or motivation to obtain the stimulation. Instead, the weight of the evidence suggests that the pleasure center of the human brain is not a single center but rather a distributed system of brain regions of which important nodes include subcortical regions (such as the nucleus accumbens
and ventral pallidum
) and cortical regions (orbitofrontal cortex
and anterior cingulate cortex
).
and Peter Milner who were investigating whether rats might be made uncomfortable by electrical stimulation of certain areas of their brain, particularly the limbic system
. In the experiment, an electrical current was given to rats if they entered a certain corner of a cage, with the hypothesis that they would stay away from that corner if the effect was uncomfortable. Instead, they came back quickly after the first stimulation and even more quickly after the second. In later experiments, they allowed the rats to press the stimulation lever themselves, to the effect that they would press it as much as seven-hundred times per hour. This region soon came to be known as the “pleasure center”.
Rats in Skinner boxes with metal electrodes implanted into their nucleus accumbens will repeatedly press a lever which activates this region, and will do so in preference over food and water, eventually dying from exhaustion. In rodent physiology, scientists reason that the medial forebrain bundle
is the pleasure center of rats. If a rat is given the choice between stimulating the forebrain or eating, it will choose stimulation to the point of exhaustion.
, part of the limbic system
, plays a role in sexual arousal
and the "high" derived from certain recreational drugs
. These responses are heavily modulated by dopamine
rgic projections from the limbic system.
. Some scientists contend that this connection is related to the pleasure obtained from solving problems. In a now-obsolete practice to cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of psychosurgery
, called a prefrontal lobotomy (this is actually a misnomer). Patients who underwent this procedure often became passive and lacked all motivation.
Pleasure
Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria...
. Discoveries made in the 1950s initially suggested that rodents could not stop electrically stimulating parts of their brain, mainly the nucleus accumbens
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...
, which was theorized to produce great pleasure
Pleasure
Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria...
. Further investigations revealed that the septum pellucidium and the hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
can also be targets for self-stimulation. Yet, more recent research has shown that such ‘pleasure’ electrodes do not, in fact, lead to pleasure but only a form of ‘wanting’ or motivation to obtain the stimulation. Instead, the weight of the evidence suggests that the pleasure center of the human brain is not a single center but rather a distributed system of brain regions of which important nodes include subcortical regions (such as the nucleus accumbens
Nucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...
and ventral pallidum
Ventral pallidum
The Ventral Pallidum 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 ventrolateral nucleus, and the medial dorsal nucleus....
) and cortical regions (orbitofrontal cortex
Orbitofrontal cortex
The orbitofrontal cortex is a prefrontal cortex region in the frontal lobes in the brain which is involved in the cognitive processing of decision-making...
and anterior cingulate cortex
Anterior cingulate cortex
The anterior cingulate cortex is the frontal part of the cingulate cortex, that resembles a "collar" form around the corpus callosum, the fibrous bundle that relays neural signals between the right and left cerebral hemispheres of the brain...
).
Experiments on rodents
The pleasure center was discovered in the 1950s by two brain researchers named James OldsJames Olds
James Olds was an American psychologist who co-discovered the reward center of the brain with Peter Milner while he was a postdoctoral fellow at McGill University in 1954...
and Peter Milner who were investigating whether rats might be made uncomfortable by electrical stimulation of certain areas of their brain, particularly the limbic system
Limbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
. In the experiment, an electrical current was given to rats if they entered a certain corner of a cage, with the hypothesis that they would stay away from that corner if the effect was uncomfortable. Instead, they came back quickly after the first stimulation and even more quickly after the second. In later experiments, they allowed the rats to press the stimulation lever themselves, to the effect that they would press it as much as seven-hundred times per hour. This region soon came to be known as the “pleasure center”.
Rats in Skinner boxes with metal electrodes implanted into their nucleus accumbens will repeatedly press a lever which activates this region, and will do so in preference over food and water, eventually dying from exhaustion. In rodent physiology, scientists reason that the medial forebrain bundle
Medial forebrain bundle
The Medial forebrain bundle , is a complex bundle of axons coming from the basal olfactory regions, the periamygdaloid region, and the septal nuclei.-Anatomy:...
is the pleasure center of rats. If a rat is given the choice between stimulating the forebrain or eating, it will choose stimulation to the point of exhaustion.
Nucleus accumbens
The nucleus accumbensNucleus accumbens
The nucleus accumbens , also known as the accumbens nucleus or as the nucleus accumbens septi , is a collection of neurons and forms the main part of the ventral striatum...
, part of the limbic system
Limbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
, plays a role in sexual arousal
Sexual arousal
Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...
and the "high" derived from certain recreational drugs
Recreational drug use
Recreational drug use is the use of a drug, usually psychoactive, with the intention of creating or enhancing recreational experience. Such use is controversial, however, often being considered to be also drug abuse, and it is often illegal...
. These responses are heavily modulated by dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
rgic projections from the limbic system.
Prefrontal cortex
The limbic system is also tightly connected to the prefrontal cortexPrefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...
. Some scientists contend that this connection is related to the pleasure obtained from solving problems. In a now-obsolete practice to cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of psychosurgery
Psychosurgery
Psychosurgery, also called neurosurgery for mental disorder , is the neurosurgical treatment of mental disorder. Psychosurgery has always been a controversial medical field. The modern history of psychosurgery begins in the 1880s under the Swiss psychiatrist Gottlieb Burckhardt...
, called a prefrontal lobotomy (this is actually a misnomer). Patients who underwent this procedure often became passive and lacked all motivation.
See also
- Limbic systemLimbic systemThe limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
- PalatabilityPalatabilityPalatability is the hedonic reward provided by foods or fluids that are agreeable to the "palate" in regard to the homeostatic satisfaction of nutritional, water, or energy needs. The palatability of a food or fluid, unlike its flavor or taste, varies with the state of an individual: it is lower...
- PleasurePleasurePleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria...
- reward systemReward systemIn neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...
- Skinner boxSkinner boxAn operant conditioning chamber is a laboratory apparatus used in the experimental analysis of behavior to study animal behavior. The operant conditioning chamber was created by B. F. Skinner while he was a graduate student at Harvard University...
External links
- Hedonia: TrygFonden Research Group
- Nucleus accumbens dopamine release during video games
- The role of the nucleus accumbens in the reward circuit. Part of "The Brain From Top to Bottom."
- Controversial 1950s pleasure and pain system studies - Synopsis of Dr Robert Heath's intracranial electrical stimulation research