Orbitofrontal cortex
Encyclopedia
The orbitofrontal cortex (OFC) is a prefrontal cortex
region in the frontal lobe
s in the brain
which is involved in the cognitive
processing of decision-making. It consists in non-human primates of the association cortex
areas brodmann area 11
, 12
and 13
; in humans it consists of brodmann area 10
, 11
and 47
Because of its functions in emotion
and reward
, the OFC is considered by some to be a part of the limbic system
.
The OFC anatomically is defined as the part of the prefrontal cortex that receives projections from the magnocellular, medial nucleus of the mediodorsal thalamus
. It gets its name from its position immediately above the orbits
in which the eye
s are located. Considerable individual variability has been found in the OFC of both humans and non-human primates. A related area is found in rodent
s.
shows that the human OFC is activated during intuitive coherence judgements.
(fMRI) to image the human OFC is a challenge, because this brain region is in proximity to the air-filled sinuses. This means that signal dropout, geometric distortion and susceptibility artifacts are common when using EPI at higher magnetic field strengths. Extra care is therefore recommended for obtaining a good signal from the orbitofrontal cortex, and a number of strategies have been devised, such as automatic shimming at high static magnetic field strengths.
The published neuroimaging
studies have found that the reward value, the expected reward value, and even the subjective pleasantness of foods and other reinforcers are represented in the OFC. A large meta-analysis
of the existing neuroimaging evidence demonstrated that activity in medial parts of the OFC is related to the monitoring, learning, and memory of the reward value of reinforcers, whereas activity in lateral OFC is related to the evaluation of punishers, which may lead to a change in ongoing behaviour .
Similarly, a posterior-anterior distinction was found with more complex or abstract reinforcers (such as monetary gain and loss) being represented more anteriorly in the orbitofrontal cortex than less-complex reinforcers such as taste. It has even been proposed that the human OFC has a role in mediating subjective hedonic experience .
The orbitofrontal cortex (OFC) represents the main neocortical target of primary olfactory cortex. In non-human primates, the olfactory neocortex
is situated along the basal surface of the caudal frontal lobes, encompassing agranular and dysgranular OFC medially and agranular insula
laterally, where this latter structure wraps onto the posterior orbital surface. Direct afferent inputs arrive from most primary olfactory areas, including piriform cortex, amygdala, and entorhinal cortex, in the absence of an obligatory thalamic relay. .
The second component of the test is "extinction". Again, participants learn to press the button for picture A but not picture B. However this time, instead of the rules reversing, the rule changes altogether. Now the participant will be punished for pressing the button in response to either picture. The correct response is not to press the button at all, but people with OFC dysfunction find it difficult to resist the temptation to press the button despite being punished for it.
Iowa gambling task
This simulation of real life decision-making is widely used in cognition and emotion research. Participants are presented with four virtual decks of cards on a computer screen. They are told that each time they choose a card they will win some game money. Every so often, however, when they choose a card they will win lose some money. They are told that the aim of the game is to win as much money as possible. The task is meant to be opaque, i.e., participants are not meant to consciously work out the rule, and they are supposed to choose cards based on their "gut reaction." Two of the decks are "bad decks," which means that, over a long enough time, they will make a net loss; the other two decks are "good decks" and will make a net gain over time. Most healthy participants sample cards from each deck, and after about 40 or 50 selections are fairly good at sticking to the good decks. Patients with OFC dysfunction, however, continue to perseverate
with the bad decks, sometimes even though they know that they are losing money overall. Concurrent measurement of galvanic skin response
shows that healthy participants show a "stress" reaction to hovering over the bad decks after only 10 trials, long before conscious sensation that the decks are bad. By contrast, patients with OFC dysfunction never develop this physiological reaction to impending punishment. Bechara and his colleagues explain this in terms of the somatic markers hypothesis
. The Iowa gambling task is currently being used by a number of research groups using fMRI to investigate which brain regions are activated by the task in healthy volunteers as well as clinical groups with conditions such as schizophrenia
and obsessive compulsive disorder.
, the test is also sensitive to patients with OFC dysfunction, who cannot judge when something socially awkward has happened despite appearing to understand the story perfectly well.
typically leads to a pattern of disinhibited behaviour. Examples include swearing excessively, hypersexuality, poor social interaction, compulsive gambling, drug use (including alcohol and tobacco), and poor empathising ability. Disinhibited behaviour by patients with some forms of frontotemporal dementia
is thought to be caused by degeneration of the OFC.
Prefrontal 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...
region in the frontal lobe
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
s in the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
which is involved in the cognitive
Cognition
In science, cognition refers to mental processes. These processes include attention, remembering, producing and understanding language, solving problems, and making decisions. Cognition is studied in various disciplines such as psychology, philosophy, linguistics, and computer science...
processing of decision-making. It consists in non-human primates of the association cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
areas brodmann area 11
Brodmann area 11
Brodmann area 11 is one of Brodmann's cytologically defined regions of the brain. It is involved in planning, reasoning, and decision making.-Human:Brodmann area 11, or BA11, is part of the frontal cortex in the human brain...
, 12
Brodmann area 12
Brodmann area 12 is a subdivision of the cerebral cortex of the guenon defined on the basis of cytoarchitecture. It occupies the most rostral portion of the frontal lobe. Brodmann-1909 did not regard it as homologous, either topographically or cytoarchitecturally, to rostral area 12 of the human...
and 13
Brodmann area 13
Brodmann area 13 is a subdivision of the cerebral cortex as defined on the guenon monkey and on the basis of cytoarchitecture. Brodmann area 13 is found in humans, however it seems to act as a bridge between the lateral and medial layers of the brain...
; in humans it consists of brodmann area 10
Brodmann area 10
Brodmann area 10, or BA10 is the frontopolar part of the frontal cortex in the human brain. BA10 was originally defined in terms of cytoarchitectonic traits in autopsy brains; modern functional imaging research cannot directly identify these boundaries and the terms anterior prefrontal, rostral...
, 11
Brodmann area 11
Brodmann area 11 is one of Brodmann's cytologically defined regions of the brain. It is involved in planning, reasoning, and decision making.-Human:Brodmann area 11, or BA11, is part of the frontal cortex in the human brain...
and 47
Brodmann area 47
Brodmann area 47, or BA47, is part of the frontal cortex in the human brain. Curving from the lateral surface of the frontal lobe into the ventral frontal cortex. It is below areas BA10 and BA45, and beside BA11....
Because of its functions in emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...
and reward
Reward system
In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects...
, the OFC is considered by some to be a 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...
.
The OFC anatomically is defined as the part of the prefrontal cortex that receives projections from the magnocellular, medial nucleus of the mediodorsal thalamus
Medial dorsal nucleus
The medial dorsal nucleus is a large nucleus in the thalamus.It is believed to play a role in memory.-Anatomy:...
. It gets its name from its position immediately above the orbits
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
in which the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
s are located. Considerable individual variability has been found in the OFC of both humans and non-human primates. A related area is found in rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s.
Functions of the human orbitofrontal cortex
The human OFC is among the least-understood regions of the human brain; but it has been proposed that the OFC is involved in sensory integration, in representing the affective value of reinforcers, and in decision-making and expectation. In particular, the human OFC is thought to regulate planning behavior associated with sensitivity to reward and punishment. This is supported by research in humans, non-human primates, and rodents. Human research has focused on neuroimaging research in healthy participants and neuropsychology research in patients with damage to discrete parts of the OFC. Research at the University of LeipzigUniversity of Leipzig
The University of Leipzig , located in Leipzig in the Free State of Saxony, Germany, is one of the oldest universities in the world and the second-oldest university in Germany...
shows that the human OFC is activated during intuitive coherence judgements.
Neuroimaging research in healthy participants
Using functional magnetic resonance imagingFunctional magnetic resonance imaging
Functional magnetic resonance imaging or functional MRI is a type of specialized MRI scan used to measure the hemodynamic response related to neural activity in the brain or spinal cord of humans or other animals. It is one of the most recently developed forms of neuroimaging...
(fMRI) to image the human OFC is a challenge, because this brain region is in proximity to the air-filled sinuses. This means that signal dropout, geometric distortion and susceptibility artifacts are common when using EPI at higher magnetic field strengths. Extra care is therefore recommended for obtaining a good signal from the orbitofrontal cortex, and a number of strategies have been devised, such as automatic shimming at high static magnetic field strengths.
The published neuroimaging
Neuroimaging
Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/pharmacology of the brain...
studies have found that the reward value, the expected reward value, and even the subjective pleasantness of foods and other reinforcers are represented in the OFC. A large meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
of the existing neuroimaging evidence demonstrated that activity in medial parts of the OFC is related to the monitoring, learning, and memory of the reward value of reinforcers, whereas activity in lateral OFC is related to the evaluation of punishers, which may lead to a change in ongoing behaviour .
Similarly, a posterior-anterior distinction was found with more complex or abstract reinforcers (such as monetary gain and loss) being represented more anteriorly in the orbitofrontal cortex than less-complex reinforcers such as taste. It has even been proposed that the human OFC has a role in mediating subjective hedonic experience .
The orbitofrontal cortex (OFC) represents the main neocortical target of primary olfactory cortex. In non-human primates, the olfactory neocortex
Neocortex
The neocortex , also called the neopallium and isocortex , is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI...
is situated along the basal surface of the caudal frontal lobes, encompassing agranular and dysgranular OFC medially and agranular insula
Agranular insula
Agranular insula is a portion of the cerebral cortex defined on the basis of internal structure in the human, the macaque, the rat, and the mouse. Classified as allocortex , it is in primates distinguished from adjacent neocortex by absence of the external granular layer and of the internal...
laterally, where this latter structure wraps onto the posterior orbital surface. Direct afferent inputs arrive from most primary olfactory areas, including piriform cortex, amygdala, and entorhinal cortex, in the absence of an obligatory thalamic relay. .
Visual discrimination test
This has two components. In the first component, "reversal learning", participants are presented with one of two pictures, A and B. They learn that they will be rewarded if they press a button when picture A is displayed, but punished if they press the button when picture B is displayed. Once this rule has been established, the rule swaps. In other words, now it is correct to press the button for picture B, not picture A. Most healthy participants pick up on this rule reversal almost immediately, but patients with OFC damage continue to respond to the original pattern of reinforcement, although they are now being punished for persevering with it. Rolls et al. noted that this pattern of behaviour is particularly unusual given that the patients reported that they understood the rule.The second component of the test is "extinction". Again, participants learn to press the button for picture A but not picture B. However this time, instead of the rules reversing, the rule changes altogether. Now the participant will be punished for pressing the button in response to either picture. The correct response is not to press the button at all, but people with OFC dysfunction find it difficult to resist the temptation to press the button despite being punished for it.
Iowa gambling taskIowa gambling taskThe Iowa gambling task is a psychological task thought to simulate real-life decision making.It was introduced by Antoine Bechara, António Damásio, Daniel Tranel and Steven Anderson, then researchers at the University of Iowa...
This simulation of real life decision-making is widely used in cognition and emotion research. Participants are presented with four virtual decks of cards on a computer screen. They are told that each time they choose a card they will win some game money. Every so often, however, when they choose a card they will win lose some money. They are told that the aim of the game is to win as much money as possible. The task is meant to be opaque, i.e., participants are not meant to consciously work out the rule, and they are supposed to choose cards based on their "gut reaction." Two of the decks are "bad decks," which means that, over a long enough time, they will make a net loss; the other two decks are "good decks" and will make a net gain over time. Most healthy participants sample cards from each deck, and after about 40 or 50 selections are fairly good at sticking to the good decks. Patients with OFC dysfunction, however, continue to perseveratePerseveration
Perseveration is the repetition of a particular response, such as a word, phrase, or gesture, despite the absence or cessation of a stimulus, usually caused by brain injury or other organic disorder. If an issue has been fully explored and discussed to a point of resolution, it is not uncommon for...
with the bad decks, sometimes even though they know that they are losing money overall. Concurrent measurement of galvanic skin response
Galvanic skin response
Skin conductance, also known as galvanic skin response , electrodermal response , psychogalvanic reflex , skin conductance response or skin conductance level , is a method of measuring the electrical conductance of the skin, which varies with its moisture level...
shows that healthy participants show a "stress" reaction to hovering over the bad decks after only 10 trials, long before conscious sensation that the decks are bad. By contrast, patients with OFC dysfunction never develop this physiological reaction to impending punishment. Bechara and his colleagues explain this in terms of the somatic markers hypothesis
Somatic markers hypothesis
The somatic-marker hypothesis proposes a mechanism by which emotional processes can guide behavior, particularly decision-making. This hypothesis has been formulated by Antonio Damasio.-Hypothesis:...
. The Iowa gambling task is currently being used by a number of research groups using fMRI to investigate which brain regions are activated by the task in healthy volunteers as well as clinical groups with conditions such as schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
and obsessive compulsive disorder.
Faux pas test
This is a series of vignettes recounting a social occasion during which someone said something that should not have been said, or an awkward occurrence. The participant's task is to identify what was said that was awkward, why it was awkward, how people would have felt in reaction to the faux pas and a factual control question. Although first designed for use in people on the autism spectrumAutism spectrum
The term "autism spectrum" is often used to describe disorders that are currently classified as pervasive developmental disorders. Pervasive developmental disorders include autism, Asperger syndrome, Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise...
, the test is also sensitive to patients with OFC dysfunction, who cannot judge when something socially awkward has happened despite appearing to understand the story perfectly well.
Consequences of damage to the OFC
Destruction of the OFC through acquired brain injuryAcquired brain injury
An acquired brain injury is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, emotional, or behavioural impairments that lead to permanent...
typically leads to a pattern of disinhibited behaviour. Examples include swearing excessively, hypersexuality, poor social interaction, compulsive gambling, drug use (including alcohol and tobacco), and poor empathising ability. Disinhibited behaviour by patients with some forms of frontotemporal dementia
Frontotemporal dementia
Frontotemporal dementia is a clinical syndrome caused by degeneration of the frontal lobe of the brain and may extend back to the temporal lobe...
is thought to be caused by degeneration of the OFC.
See also
- BELBICBELBICIn recent years, the use of biologically inspired methods such as the evolutionary algorithm have been increasingly employed to solve and analyze complex computational problems...
- Emotional Learning
- Phineas GagePhineas GagePhineas P. Gage was an American railroad construction foreman now remembered for his improbablesurvival of an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and for that injury's reported effects on his personality and...
- WitzelsuchtWitzelsuchtWitzelsucht, from the German witzeln, meaning to joke or wisecrack, and sucht meaning addiction or yearning, is a set of rare neurological symptoms characterized by the patient's uncontrollable tendency to make puns, tell inappropriate jokes and pointless or irrelevant stories at inconvenient moments...
- Obsessive-compulsive disorderObsessive-compulsive disorderObsessive–compulsive disorder is an anxiety disorder characterized by intrusive thoughts that produce uneasiness, apprehension, fear, or worry, by repetitive behaviors aimed at reducing the associated anxiety, or by a combination of such obsessions and compulsions...