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20-September-2008 10:21:21 - cingulate cortex Brain: Anterior cingulate cortex Medial surface of left cerebral hemisphere. NeuroNames hier-143 The Anterior cingulate cortex ACC is the frontal part of the cingulate cortex, which 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. It includes both the ventral and dorsal areas of the cingulate cortex, and appears to play a role in a wide variety of autonomic functions, such as regulating blood pressure and heart rate, as well as rational cognitive functions, such as reward anticipation, decision-making, empathy and emotion. Contents 1 Functions 2 Tasks 3 Evidence from electrical studies 4 Theory based on imaging studies 4.1 Error detection theory 4.2 Conflict monitoring theory 4.3 Evidence against error detection and conflict monitoring theory 4.4 Reward based learning theory 5 Pathology 6 ACC and consciousness 7 References 8 External links 9 See also Functions The anterior cingulate cortex can be divided anatomically based on attributed functions into executive anterior, evaluative posterior, cognitive dorsal, and emotional ventral components Bush et al., 2000. The ACC is connected with the prefrontal cortex and parietal cortex as well as the motor system and the frontal eye fields Posner DiGirolamo, 1998 making it a central station for processing top-down and bottom-up stimuli and assigning appropriate control to other areas in the brain. The ACC seems to be especially involved when effort is needed to carry out a task such as in early learning and problem solving Allman et al., 2001. Many studies attribute functions such as error detection, anticipation of tasks, motivation, and modulation of emotional responses to the ACC Bush et al., 2000; Nieuwenhuis et al., 2001; Posner DiGirolamo, 1998. ACC response in Stroop task experiments designed to measure adherence to sequential decision-making paths remains relatively elevated in typical human subjects, as the alternative - spontaneity - is sacrificed. Whereas most funded research is concentrated on reduced task focus - often diagnosed subjectively as attention deficit hyperactivity disorder ADHD - recent research using monkeys has revealed that heightened ACC activity generally associated with reduced dopamine utilization reduces capacity to learn how to use visual cues for anticipating rewards 1. The anterior cingulate cortex contains cells known as spindle neurons, which also have been found in the ACC and frontoinsular cortex of humans and other hominids great apes, as well as in humpback whales, killer whales and sperm whales. Tasks A typical task that activates the ACC involves eliciting some form of conflict within the participant that can potentially result in an error. One such task is called the Eriksen Flanker Task and simply consists of an arrow pointing to the left or right, which is flanked by two distractor arrows creating either compatible or incompatible trials Botvinick et al., 1999. Another very common conflict inducing stimulus is the Stroop task. The classic Stroop task involves naming the color ink of words that are either congruent RED written in red or incongruent RED written in blue. Conflict occurs because people's reading abilities interfere with their attempt to correctly name the word's ink color. A variation of this task is the Counting-Stroop during which people count either neutral stimuli 'dog' presented four times or interfering stimuli 'three' presented four times by pressing a button. Another version of the Stroop task named the Emotional Counting Stroop is identical to the Counting Stroop test, except that it also uses segmented or repeated emotional words such as murder, during the interference part of the task. Using different forms of conflict induction allows researchers to differentiate between the many functions of the ACC. It is worth noting that all these contrasts involve a subtraction between a more difficult type of trial and a less difficult one. There are reasons to think that ACC responses reflect this difficulty e.g. increased neural activity associated with signaling more blood flow to other brain regions, rather than cognitive conflict per se See Review by Critchely related to this. If so, the ACC response is not the neural signature of a brain region that processes the conflict, it is the neural signature of a brain region that is correlated with conflict processing somewhere else. Evidence from electrical studies Evidence for the role of the ACC as having an error detection function comes from consistent observations of error related negativity ERN uniquely generated within the ACC upon error occurrences Gehring et al., 1993; Bush et al., 2000; Holroyd et al., 2004; Luu Pederson, 2004. A distinction has been made between an ERP following incorrect responses response ERN and a signal after subjects receive feedback after erroneous responses feedback ERN. It is worth noting at this point that no-one has clearly demonstrated that the ERN comes from the ACC. Source localization of ERP components is a notoriously messy business. The ERN could come from any number of brain regions, perhaps several. In light of this, it is striking that patients with lateral PFC damage not medial showed reduced ERNs see Gehring and Knight. Reinforcement learning ERN theory poses that there is a mismatch between actual response execution and appropriate response execution, which results in an ERN discharge Bush et al., 2000; Holroyd et al., 2004. Furthermore, this theory predicts that when the ACC receives conflicting input from control areas in the brain, it determines and allocates which area should be given control over the motor system. Varying levels of dopamine are believed to influence the optimization of this filter system by providing expectations about the outcomes of an event. The ERN then, serves as a beacon to highlight the violation of an expectation Luu Pederson, 2004. Research on the occurrence of the feedback ERN shows evidence that this potential has larger amplitudes when violations of expectancy are large. In other words, if an event is not likely to happen the feedback ERN will be larger if no error is detected. Other studies have examined if the ERN is elicited by varying the cost of an error and the evaluation of a response Holroyd et al., 2004. In these trials, feedback is given about whether the participant has gained or lost money after a response. Amplitudes of ERN responses with small gains and small losses were similar. No ERN was elicited for any losses as opposed to an ERN for no wins even though both outcomes are the same. The finding in this paradigm suggests that monitoring for wins and losses is based on the relative expected gains and losses. If you get a different outcome than expected, the ERN will be larger than for expected outcomes. ERN studies have also localized specific functions of the ACC Luu Pederson, 2004. The rostral ACC seems to be active after an error commission indicating an error response function, whereas the dorsal ACC is active after both an error and feedback suggesting a more evaluative function for fMRI evidence see also Bush et al., 2002; Polli et al., 2005; Taylor et al., 2006. This evaluation is emotional in nature and highlights the amount of distress associated with a certain error Bush et al., 2000. Summarizing the evidence found by ERN studies it appears to be the case that ACC receives information about a stimulus, selects an appropriate response, monitors the action, and adapts behavior if there is a violation of expectancy Luu Pederson, 2004. Theory based on imaging studies The range of functions attributed to the ACC has been synthesized from many fMRI studies. Some theories focus strictly on the error detection properties of the ACC, while others incorporate conflict monitoring, emotional effects, and reward-based learning. None of the current theories can fully explain the complete picture of the ACC, but each contributes to a piece of the puzzle. Some of the main theories will be discussed in this section. Error detection theory The most basic form of ACC theory states that the ACC is involved with error detection Bush et al., 2000. Evidence for this theory has been derived from studies involving a Stroop task Posner DiGirolamo, 1998. However, ACC activation is also active during correct response and this has been shown using a letter task whereby participants had to respond to the letter X after an A was presented and ignore all other letter combinations with some letters being more competitive than others Carter et al., 1998. They found that for more competitive stimuli ACC activation was greater. This study highlights the important notion that the ACC is not merely involved with detecting an error, but actually evaluates the degree of conflict. Conflict monitoring theory This theory poses that the ACC's primary function is the monitoring of conflict. In the example of the Eriksen Flanker Test, incompatible trials produce the most conflict and therefore the most activation by the ACC. Evidence for this theory has been demonstrated Botvinick et al., 1999. Upon detection of a conflict the ACC then provides cues to other areas in the brain to cope with the conflicting control systems. One weakness of this theory is that it cannot explain some evidence obtained by electrical studies Holroyd et al., 2004; Luu Pederson, 2004; Nieuwenhuis et al., 2001 that demonstrate the effects of giving feedback after responses because the theory describes the ACC as strictly monitoring conflict, not as having evaluative properties. Evidence against error detection and conflict monitoring theory Several recent studies, particularly those examining task performance related to error and conflict processes in patients with ACC damage, cast doubt on the necessity of this region for these functions. Baird et al. 2propose that their data may imply that the ACC does not have a central role in cognition Nachev et al. 3 state that The highly influential notion of conflict monitoring by the anterior cingulate has been called into question by monkey single-cell neurophysiology and lesion studies in monkeys and humans. The comprehensive Critchley review 4 states that The cognitive consequences of anterior cingulate lesions remain rather equivocal, with a number of case reports of intact general neuropsychological and executive function in the presence of large anterior dorsal cingulate lesions Cohen et al., 1999; Swick and Turken, 2002; Stemmer et al., 2004; Fellows and Farah 2005. And for an evolving and now quite detailed alternative view of anterior cingulate, see Rushworth's review 2007 5 Reward based learning theory A more comprehensive and recent theory describes the ACC as a more active component and poses that it detects and monitors errors, evaluates the degree of the error, and then suggests an appropriate form of action to be implemented by the motor system. Earlier evidence from electrical studies indicate the ACC has an evaluative component and this is indeed confirmed by fMRI studies. The dorsal and rostral areas of the ACC both seem to be affected by rewards and losses associated with errors. During one study, participants received monetary rewards and losses for correct and incorrect responses respectively Bush et al., 2002. Largest activation in the dACC was shown during loss trials. This stimulus did not elicit any errors and thus error detection and monitoring theories cannot fully explain why this ACC activation would occur. The dorsal part of the ACC seems to play a key role in reward-based decision making and learning. The rostral part of the ACC, on the other hand, is believed to be more involved with affective responses to errors. In an interesting expansion of the previously described experiment, the effects of rewards and costs on ACC's activation during error commission was examined Taylor et al., 2006. Participants performed a version of the Eriksen Flanker Task using a set of letters assigned to each response button instead of arrows. Targets were flanked by either a congruent or incongruent set of letters. Using an image of a thumb up, down, or neutral participants received feedback on how much money they gained or lost. The researchers found greater rostral ACC activation when participants lost money during the trials. The participants reported being frustrated when making mistakes. Because the ACC is intricately involved with error detection and affective responses, it may very well be that this area forms the bases of self-confidence. Taken together, these findings indicate that both the dorsal and rostral areas are involved in evaluating the extent of the error and optimizing subsequent responses. A study that confirming this notion explored the functions of both the dorsal and rostral areas of the ACC involved using a saccade task Polli et al., 2005. Participants were shown a cue that indicated whether they had to make either a post saccade or an anti-saccade. An anti-saccade requires suppression of a distracting cue because the target appears in the opposite location causing the conflict. Results showed differing activation for the rostral and dorsal ACC areas. Early correct anti-saccade performance was associated with rostral activation. The dorsal area, on the other hand, was activated when errors were committed, but also for correct responses. Whenever the dorsal area was active, fewer errors were committed providing more evidence that the ACC is involved with effortful performance. The second finding showed that during error trials, the ACC activated later than for correct responses clearly indicating a kind of evaluative function. Incorporating the findings of the previously discussed studies, the rostral and dorsal areas of the ACC seem to be monitoring for errors and, when they occur, evaluate their severity. The ACC can then send a form of affective response based on the severity of the error and so provides feedback about what just happened and what to do next. Pathology Stimulation of the anterior cingulate also known as Area 25 with low dosages of electric current in neurosurgical studies has been shown to improve depression in a portion of test subjects. Studying the effects of damage to the ACC provides insights into the type of functions it serves in the intact brain. Behavior that is associated with lesions in the ACC includes: inability to detect errors, severe difficulty with resolving stimulus conflict in a Stroop task, emotional instability, inattention, and akinetic mutism Bush et al., 2000; Posner DiGirolamo, 1998. There is evidence that damage to ACC is present in patients with schizophrenia, where studies have shown patients have difficulty in dealing with conflicting spatial locations in a Stroop-like task and having abnormal ERNs Holroyd et al., 2004; Posner DiGirolamo, 1998. Participants with ADHD were found to have reduced activation in the dorsal area of the ACC when performing the Stroop task Bush et al., 1999. Together these findings corroborate results from imaging and electrical studies about the variety of functions attributed to the ACC. There is evidence that this area may have a role in Obsessive Compulsive Disorder due to the fact that what appears to be an unnaturally low level of glutamate activity in this region has been observed in patients with the disorder, 6 in strange contrast to many other brain regions which are thought to have excessive glutamate activity in OCD. Helen S. Mayberg and two collaborators described how they cured 4 of 6 depressed people -- individuals virtually catatonic with depression despite years of talk therapy, drugs, even shock therapy -- with pacemakerlike electrodes in area 25. A decade earlier Mayberg had identified area 25 as a key conduit of neural traffic between the thinking frontal cortex and the phylogenetically older central limbic region that gives rise to emotion. She subsequently found that area 25 appeared overactive in these depressed people - like a gate left open, as she puts it - allowing negative emotions to overwhelm thinking and mood. Inserting the electrodes closed this gate and rapidly alleviated the depression of two-thirds of the trial's patients 1. ACC and consciousness The ACC area in the brain is associated with many functions that require conscious experience by the viewer. Higher ACC activation levels were found for more emotionally aware female participants when shown short 'emotional' video clips Lane et al., 1998. Better emotional awareness is associated with improved recognition of emotional cues or targets which is reflected by ACC activation. The idea of awareness being associated with the ACC has some evidence with it, in that it seems to be the case that when subject's responses are not congruent with actual responses, a larger ERN is produced Luu Pederson, 2004. One study found an ERN even when subjects were not aware of their error Luu Pederson, 2004. Awareness may not be necessary to elicit an ERN, but it could influence the effect of the amplitude of the feedback ERN. Relating back to the reward based learning theory, awareness could modulate expectancy violations. Increased awareness could result in decreased violations of expectancies and decreased awareness could achieve the opposite effect. Further research is needed to completely understand the effects of awareness on ACC activation. References ^ Deep Brain Stimulation for Treatment-Resistant Depression. Helen S. Mayberg et al. in Neuron, Vol. 45, No. 5, pages 651-660; March 3, 2005. Allman, J. M., Hakeem, A., Erwin, J. M., Nimchinsky, E., Hof, P. 2001. The anterior cingulate cortex: The evolution of an interface between emotion and cognition. Annals New York Academy of Sciences, 935, 107-117. Botvinick, M., Nystrom, L. E., Fissell, K., Carter, C. S., Cohen, J. D. 1999. Conflict monitoring versus selection-for-action in anterior cingulate cortex. Nature, 402, 179-181. Bush, G., Frazier, J. A., Rauch, S. L., Seidman, L. J., Whalen, P. J., Jenike, M. A., et al. 1999. Anterior cingulate cortex dysfunction in attention-deficit/hyperactivity disorder revealed by fMRI and the counting stroop. Society of Biological Psychiatry, 45, 1542-1552. Bush, G., Luu, P., Posner, M. I. 2000. Cognitive and emotional influences in anterior cingulate cortex. Trends in Cognitive Science, 4, 215-222. Bush, G., Vogt, B. A., Holmes, A., Dale, A. M., Greve, D., Jenike, M. A., et al. 2002. Dorsal anterior cingulate cortex: A role in reward-based decision making. Proceedings of the National Academy of Sciences, 991, 523-528. Carter, C. S., Braver, T. S., Barch, D. M., Botvinick, M., Noll, D., Cohen, J. D. 1998. Anterior cingulate cortex, error detection, and on-line monitoring of performance. Science, 280, 747-749. Holroyd, C. B., Nieuwenhuis, S., Mars, R. B., Coles, M. G. H. 2004. Anterior cingulate cortex, selection for action, and error processing. In M. I. Posner Ed., Cognitive neuroscience of attention pp. 219-231. New York: Guilford Publication, Inc. Gehring, W. J., Goss, B., Coles, M.G.H., Meyer, D.E., Donchin, E. 1993. A neural system for error-detection and compensation. Psychological Science, 4 6, 385-390. Lane, R. D., Reiman, E. M., Axelrod, B., Yun, L., Holmes, A., Schwartz, G. E. 1998. Neural correlates of levels of emotional awareness: Evidence of an interaction between emotion and attention in the anterior cingulate cortex. Journal of Cognitive Neuroscience, 104, 525-535. Luu, P., Pederson, S. M. 2004. The anterior cingulate cortex: Regulating actions in context. In M. I. Posner Ed., Cognitive neuroscience of attention. New York: Guilford Publication, Inc. Nieuwenhuis, S., Ridderinkhof, K. R., Blom, J., Band, G. P., Kok, A. 2001. Error-related brain potentials are differentially related to awareness of response errors: evidence from an antisaccade task. Psychophysiology, 38, 752-760. Polli, F. E., Barton, J. J. S., Cain, M. S., Thakkar, K. N., Rauch, S. L., Manoach, D. S. 2005. Rostral and dorsal anterior cingulate cortex make dissociable contributions during antisaccade error commission. Proceedings of the National Academy of Sciences, 10243, 700-705. Posner, M. I., DiGirolamo, G. J. 1998. Executive attention: Conflict, target detection, and cognitive control. In R. Parasuraman Ed., The Attentive Brain: MIT Press. Taylor, S. F., Martis, B., Fitzgerald, K. D., Welsh, R. C., Abelson, J. L., Liberzon, I., et al. 2006. Medial frontal cortex activity and loss-related responses to errors. The Journal of Neuroscience, 2615, 4063-4070. Mayberg, H. S., et al. 2005. Deep Brain Stimulation for Treatment-Resistant Depression Neuron, 455, pages 651-660; 2005 Goldapple, K., et al., 2004 Modulation of Cortical-limbic Pathways in Major Depression, Archives of General Psychiatry, 61, pp34-41. External links The Anterior Cingulate Cortex: The Evolution of an Interface Between Emotion and Cognition, paper by John Allman et al allmanlab.caltech.edu - John Allman Lab TaipeiTimes.com - Know Thyself and Others NeuroNames hier-143 Brain Implant Offers Hope for Severely Depressed Deep Brain Stimulation for Treatment-Resistant Depression, paper by Helen S. Mayberg et al. March 3, 2005. Modulation of Cortical-limbic Pathways in Major Depression, paper by K. Goldapple et al. January 1, 2004. Scientific American, Volume 17, Number 4, pp26-31, article by David Dobbs, July 30, 2006. Painful Stimuli Recorded Over the Human Anterior Cingulate Gyrus, Lenz, et al., J. Neurophysiol, 79: 2231-2234, 1998. See also Cingulate cortex Cingulate gyrus Cingulate sulcus v d e Brain: telencephalon cerebrum, cerebral cortex, cerebral hemispheres Frontal lobe Precentral gyrus Primary motor cortex, 4 Superior frontal gyrus/Frontal eye fields 6, 8, 9, Middle frontal gyrus 46, Inferior frontal gyrus/Broca's area 44-Pars opercularis, 45-Pars triangularis Orbitofrontal cortex 10, 11, 12, 47 Prefrontal cortex, Premotor cortex Precentral sulcus - Superior frontal sulcus - Inferior frontal sulcus - Olfactory sulcus Parietal lobe Somatosensory cortex Primary 1, 2, 3, 43, Secondary 5, Precuneus 7m - Parietal operculum Parietal lobules Superior 7l, Inferior 40, Angular gyrus 39 Intraparietal sulcus, Marginal sulcus Occipital lobe Primary visual cortex 17, Cuneus, Lingual gyrus, Lateral occipital gyrus 18, 19 Calcarine fissure Temporal lobe Primary auditory cortex 41, 42, Superior temporal gyrus 38, 22/Wernicke's area, Middle temporal gyrus 21, Inferior temporal gyrus 20 Fusiform gyrus 37 Medial temporal lobe Amygdala, Parahippocampal gyrus 27, 28, 34, 35, 36 Cingulate cortex/gyrus Subgenual area 25, Anterior cingulate 24, 32, 33, Posterior cingulate 23, 31, Retrosplenial cortex 26, 29, 30 Callosal sulcus Interlobar sulci/fissures lateral: Central frontal+parietal, Lateral frontal+parietal+temporal, Parietoöccipital medial: Medial longitudinal, Cingulate frontal+cingulate, Collateral temporal+occipital White matter tracts Commissural fibers - Association fibers Internal capsule Anterior limb, Genu, Posterior limb, Corona radiata, External capsule, Lamina terminalis, Extreme capsule, Semioval center Olfactory tract - Terminal stria - Diagonal band of Broca Other Insular cortex gray: Olfactory bulb, Anterior olfactory nucleus, Basal optic nucleus of Meynert, Substantia innominata, Anterior perforated substance Corpus striatum - Limbic lobe Some categorizations are approximations, and some Brodmann areas span gyri. Retrieved from http://en..org/wiki/Anterior_cingulate_cortex Categories: Cerebrum | Neuroanatomy Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages Italiano Latviešu Nederlands This page was last modified on 6 August 2008, at 01:3
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