Orbitofrontal cortex 3766002 215515438 2008-05-28T15:21:44Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Infobox Brain| Name = {{PAGENAME}} | Latin = | GraySubject = 189 | GrayPage = 822 | Image = OFC.JPG | Caption = Approximate location of the OFC shown on a sagittal MRI | Image2 = Gray729.png | Caption2 = Orbital surface of left frontal lobe. | IsPartOf = | Components = | Artery = | Vein = | BrainInfoType = hier | BrainInfoNumber = 73 | MeshName = | MeshNumber = | }} The '''orbitofrontal cortex''' (OFC) is a region of association [[cerebral cortex|cortex]] of the [[human brain]] involved in [[cognition|cognitive]] processes such as [[decision-making]]. The name of this region is based upon the region's location within the [[frontal lobe]]s, resting above the [[orbit (anatomy)|orbits]] of the [[eye]]s. It is defined as the part of the prefrontal cortex that receives projections from the magnocellular, medial, nucleus of the mediodorsal [[thalamus]] <ref>Fuster, J.M. ''The Prefrontal Cortex'', (Raven Press, New York, 1997).</ref>. Considerable individual variability has been found in the OFC of both humans and non-human primates. Because of its functions in [[emotion]] and [[reward system|reward]], the OFC is considered by some to be a part of the [[limbic system]]. ===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.<ref name="Kringelbach 2005">Kringelbach, M. L. (2005) "The orbitofrontal cortex: linking reward to hedonic experience." ''Nature Reviews Neuroscience'' '''6''': 691-702.</ref> In particular, the human OFC is thought to regulate planning behavior associated with sensitivity to reward and punishment.<ref name="Bechara 1994">Bechara, A.; Damasio, A. R.; Damasio H. & Anderson, S.W. (1994) "Insensitivity to future consequences following damage to human prefrontal cortex". ''Cognition'' '''50''': 7-15.</ref> 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. ===[[Neuroimaging]] research in healthy participants=== It is important to realise that using [[functional magnetic resonance imaging]] (fMRI) to image the human OFC is a challenge, as this brain region is in close proximity to the air-filled sinuses, which 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, e.g., <ref>{{cite journal | pmid = 12377170 | author = J. Wilson, M. Jenkinson, I. E. T. de Araujo, [[Morten L. Kringelbach]], [[E. T. Rolls]], & [[Peter Jezzard]] | year = [[2002]] | title = Fast, fully automated global and local magnetic field optimization for fMRI of the human brain | journal = [[NeuroImage]] | volume = 17 | issue = 2 | month = October | pages = 967&ndash;976 | doi = 10.1016/S1053-8119(02)91172-9 }}</ref>. 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 <ref>{{Cite journal | author = Kringelbach, M. L. and Rolls, E. T. | year = [[2004]] | title = The functional neuroanatomy of the human orbitofrontal cortex: evidence from neuroimaging and neuropsychology | journal = [[Progress in Neurobiology]] | volume = 72 | pages = 341&ndash;372 | doi = 10.1016/j.pneurobio.2004.03.006 }}</ref>. 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 <ref name="Kringelbach 2005" />. ===Neuropsychology research in patients=== * The [[visual discrimination test]]<ref>Rolls, E. T.; Hornak, J.; Wade, D. & McGrath, J. (1994) "Emotion-related learning in patients with social and emotional changes associated with frontal lobe damage." ''J Neurol Neurosurg Psychiatry'' '''57''': 1518-1524.</ref> has two components: reversal learning and extinction. In "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. * The [[Iowa gambling task]] is a simulation of real life [[decision-making]], which is widely used in research of cognition and emotion.<ref name="Bechara 1994" /> 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 money, but will also lose some money, too. 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 [[Perseveration|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 (including the [[Institute of Psychiatry]] and [[Institute of Neurology]]) 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 [[Faux pas test]] is a series of vignettes recounting a social occasion wherein someone said something he should not have said, or something awkward. 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 spectrum]]<ref>Stone, V.E.; Baron-Cohen, S. & Knight, R. T. (1998a) "Frontal Lobe Contributions to Theory of Mind." ''Journal of Medical Investigation'' '''10''': 640-656.</ref>, 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. ==Everyday consequences of damage to the OFC== Destruction of the OFC through [[acquired brain injury]] typically leads to a pattern of [[disinhibited]] behaviour. Examples include swearing excessively, hypersexuality, poor social interaction, compulsive gambling, excessive alcohol / smoking / drug use, and poor empathising ability. Disinhibited behaviour by patients with some forms of [[frontotemporal dementia]] is thought to be caused by degeneration of the OFC<ref> Snowden, J. S.; Bathgate, D.; Varma, A.; Blackshaw, A.; Gibbons, Z. C. & Neary. D. (2001) "Distinct behavioural profiles in frontotemporal dementia and semantic dementia". ''J Neurol Neurosurg Psychiatry'' '''70''': 323-332.</ref>. Patients with damage to the OFC tend to make rash decisions, and typically manage their finances poorly. ==See also== * [[Phineas Gage]] * [[Witzelsucht]] * [[Obsessive-compulsive disorder]] ==References== <references/> ==External links== * [http://cercor.oxfordjournals.org/cgi/content/full/10/3/205 ''Cerebral Cortex'' special issue on orbitofrontal cortex] {{Limbic system}} {{Prosencephalon}} [[Category:Neuroanatomy]] [[Category:Cerebrum]] [[Category:Limbic system]] [[fr:Cortex orbitofrontal]] [[nl:Orbitofrontale cortex]]