project:brain_hacking:tdcs:pfc
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
project:brain_hacking:tdcs:pfc [2012/05/20 22:21] – pictures ata | project:brain_hacking:tdcs:pfc [2013/12/18 10:14] (current) – improve citation pasky | ||
---|---|---|---|
Line 1: | Line 1: | ||
+ | ====== PREFRONTAL CORTEX ====== | ||
+ | < | ||
+ | |||
+ | |||
+ | |||
+ | ===== Introduction ===== | ||
+ | The prefrontal cortex (PFC) governs the executive control of information processing | ||
+ | and behavioral expression, including the ability to selectively attend and maintain information, | ||
+ | inhibit irrelevant stimuli and impulses, and evaluate and select the appropriate | ||
+ | response . This cognitive and behavioral control facilitates successful achievement of complex goal-directed behaviors. Some | ||
+ | evidence suggests that all regions of the PFC (dorsal, ventral, lateral, medial) have the | ||
+ | capacity to perform the same type of executive control functions (i.e. evaluate, maintain, | ||
+ | inhibit, or select) [(Duncan and Owen 2000)]. However, other evidence indicates | ||
+ | that particular regions of the PFC are biased toward specific functions and information | ||
+ | domains (Shimamura 2000,Muller et al. 2002). | ||
+ | |||
+ | {{pfc.jpg}} | ||
+ | {{areas.jpg}} | ||
+ | {{http:// | ||
+ | |||
+ | |||
+ | ====== OFC ====== | ||
+ | {{http:// | ||
+ | {{http:// | ||
+ | |||
+ | ===== Connections ===== | ||
+ | * receives inputs from every sensory modality | ||
+ | * has immense reciprocal connections with subcortical structures, such as | ||
+ | * the amygdala, thalamus, and periaquaductal gray area | ||
+ | * Dopamine projections from the nucleus accumbens and ventral tegmental area also project significantly to the orbitofrontal cortex | ||
+ | * has direct projections to the primary and secondary sensory cortices | ||
+ | * closely connected to the dorsolateral prefrontal cortex. | ||
+ | * reciprocal projections to granular, dysgranular, | ||
+ | * The orbitofrontal cortex additionally shares extensive reciprocal connections with the amygdala, and direct and indirect connections to the hypothalamus. | ||
+ | * Additional subcortical projections are shared between the striatum, particularly ventral reward-related areas[9], | ||
+ | * The OFC projects and is neuronanatomicaly connected (via the mediodorsal nucleus of the thalamus) to the nucleus acumbens - which is associated with the reinforcing effects of drug administration [26][27][28]. The nucleus acumbens projects back to the OFC[29] , as do dopamine cells in the ventral tegmental area (VTA) [30] - the latter being associated with the positive, reinforcing effects of drugs. Limbic regions including the amygdala, hippocampus and cingulated gyrus also project to the OFC via direct and indirect pathways[27][31] and it would appear that the OFC is not only the target for reinforcing drug effects but also serves to integrate information from the limbic system, modulating the response of the limbic areas to drugs of abuse (and their rewarding effects)[16]. | ||
+ | |||
+ | ===== Function ===== | ||
+ | * dysregulated OFC connectivity/ | ||
+ | * problems with decision-making is drug addiction/ | ||
+ | * reward value, the expected reward value, and even the subjective pleasantness of foods and other reinforcers are represented in the OFC | ||
+ | * can modulate the strength of the neural | ||
+ | * suppresses neural activity related to aversive or painful sensations | ||
+ | * OFC lesion neural response not habituate. | ||
+ | * normally inhibits aversive sensations very early in sensory processing by regulating neural activity in posterior sensory association areas. | ||
+ | * OFC lesion patients displayed more surprise behavior and reported more fear | ||
+ | than the normal controls in response to the noise. | ||
+ | * calculates or represents the emotions that individuals would experience if they pursued each alternative.These emotions then bias the decisions that individuals reach. | ||
+ | * enables individuals to anticipate whether some course of action will evoke positive or negative emotions, both immediately and in the future. | ||
+ | * moral behavior. That is, when the orbitofrontal cortex is activated, individuals choose the courses of action that tend to be rewarded, rather than punished, by other people. | ||
+ | * improve future predictions - adapt to unexpected outcomes. | ||
+ | * facilitates empathy. | ||
+ | * OFC neurons are activated by rewards and cues that predict rewards in a way that reflects their incentive value, typically independent of the predictive cue or associated response | ||
+ | * OFC represents bad outcomes as well as good ones | ||
+ | * OFC plays a critical role in evoking the original learning and integrating it with the new value of the outcome to guide responding. | ||
+ | * Damage to OFC and medial PFC is associated with increased risk for the display of reactive | ||
+ | aggression especially when the lesion occurs in childhood | ||
+ | |||
+ | ==== MOFC ==== | ||
+ | * learning, and memory of the reward value of reinforcers | ||
+ | * When people allowed themselves to feel | ||
+ | the full negative impact of negative scenes, | ||
+ | |||
+ | ==== LOFC ==== | ||
+ | * evaluation of punishers, which may lead to a change in ongoing behaviour | ||
+ | * LOFC (bilaterally) + and DLPFC (bilaterally) + during | ||
+ | anticipation of pain predict less pain related activity in the thalamus, insula and dorsal | ||
+ | ACC. In addition, both the OFC and DLPFC activity correlated with self-report of | ||
+ | decreased pain. These findings add a temporal component and suggest that the OFC can | ||
+ | inhibit pain sensation by increasing activity in the anticipation of a painful stimulus. | ||
+ | * facilitates selective attention by controlling the interference of | ||
+ | irrelevant emotional information in the environment on spatial attention. | ||
+ | * The faces had either a neutral or fearful expression. The | ||
+ | results showed that the lateral OFC was engaged when fearful faces had to be ignored in | ||
+ | order to make a judgement about the houses. However, the lateral OFC was not active | ||
+ | when ignoring neutral faces. | ||
+ | * enhanced attention by suppressing the neural activity | ||
+ | associated with the representation of the interfering stimulus | ||
+ | * L-lateral OFC/VLPFC as well as L-DLPFC were both involved in ignoring the fearful face. | ||
+ | + in these regions in anticipation of a “to be ignored” fearful stimulus, | ||
+ | suggesting that these subjects are employing VLPFC activity to help them suppress the | ||
+ | interfering influence of the threat related stimulus when the emotional information is | ||
+ | not relevant to the task. However, people high in anxiety did not recruit these regions to | ||
+ | help them ignore the fearful stimuli, suggesting a failure in top down regulatory control | ||
+ | in anxiety | ||
+ | * multiple PFC regions, including the lateral OFC/VLPFC, control emotional experience and expression | ||
+ | * depressed individuals had more R-lateral OFC/VLPFC activity when | ||
+ | ignoring sad words (and attending to happy words) as compared to ignoring happy (and | ||
+ | attending to sad words). | ||
+ | * inverse correlation with the L-lateral OFC and the | ||
+ | influence of mood priming on betting. This shows that the lateral | ||
+ | OFC regulated the influence of emotion on decision-making | ||
+ | * L-lateral OFC was also involved when subjects were instructed to use | ||
+ | the emotional information as part of their betting strategy. This suggests that the lateral | ||
+ | OFC may be involved in inhibiting emotional information when it is irrelevant and | ||
+ | integrating it when it is relevant to the decision. | ||
+ | * more right lateral OFC activity in response to angry | ||
+ | expressions as compared to other facial expressions | ||
+ | * in addition to providing the neural mechanism of inhibition, the | ||
+ | lateral OFC may also register and implement signals indicating the need to inhibit, such | ||
+ | as an angry or embarrassed facial expression | ||
+ | < | ||
+ | |||
+ | ==== VLOFC ==== | ||
+ | * effect of placebo - increased lateral OFC/VLPFC activity is related to - pain | ||
+ | | ||
+ | * R-VLPFC mediates a conscious, cognitive evaluation and expectation associated with placebo T | ||
+ | * facilitates working memory by inhibiting proactive interference | ||
+ | Proactive interference occurs when a recent but irrelevant memory interferes with | ||
+ | current recognition or recall. | ||
+ | * Greater left VLPFC activity is associated with a | ||
+ | correct response on trials containing a familiar (“lure”) item. In other words, greater | ||
+ | VLPFC activity is associated with resistance to proactive interference . | ||
+ | * VLPFC help maintain goal oriented focus by suppressing the influence of interfering | ||
+ | information | ||
+ | * when subjects reappraised | ||
+ | negative scenes so that their interpretation decreased their negative feelings, the | ||
+ | VLPFC (inferior frontal gyrus BA 44, 10, 46) and the DLPFC were active . In addition, lateral OFC and VLPFC (BA 44,46) activity during reappraisal was inversely correlated with activation | ||
+ | in the amygdala. | ||
+ | * VLPFC and DLPFC activity have been observed in emotion regulation, | ||
+ | there is evidence that lateral OFC is particularly involved in strategies employed to | ||
+ | decrease negative affect. | ||
+ | * Decreasing distress by reappraisal employs VLPFC- and lateral OFC-mediated | ||
+ | top-down regulation | ||
+ | |||
+ | |||
+ | {{http:// | ||
+ | a | The proposed model. b | A schematic of the functional connectivity of one hemisphere of the orbitofrontal cortex28, 109. Information in the figure flows from bottom to top. Sensory information arrives from the periphery in the primary sensory cortices, where the stimulus identity is decoded into stable cortical representations. This information is then conveyed to brain structures in the posterior parts of the orbitofrontal cortex for further multimodal integration. The reward value of the reinforcer is assigned in more anterior parts of the orbitofrontal cortex, and from here it can be used to influence subsequent behaviour (in lateral parts of the anterior orbitofrontal cortex with connections to the anterior cingulate cortex), stored for learning and memory (in medial parts of the anterior orbitofrontal cortex) and made available for subjective hedonic experience (in the mid-anterior orbitofrontal cortex). The reward value and subjective hedonic experience can be modulated by hunger and other internal states. Important reciprocal information flows between the various regions of the orbitofrontal cortex and other brain regions. | ||
+ | |||
+ | {{http:// | ||
+ | b | The sulcal variability of the human orbitofrontal cortex is shown with ventral views of the three main patterns of gyri and sulci, taken from the left hemisphere. | ||
+ | |||
+ | ===== TESTS ===== | ||
+ | |||
+ | Visual discrimination test | ||
+ | * " | ||
+ | * " | ||
+ | |||
+ | Iowa gambling task | ||
+ | |||
+ | Faux pas test | ||
+ | |||
+ | ---- | ||
+ | |||
+ | |||
+ | * 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 | ||
+ | * medio-lateral gradient for representation of positive and negative stimuli, respectively, | ||
+ | * For example, the OFC (BA 11) and VLPFC (BA 47) are | ||
+ | active when subjects try to decrease their erotic feelings to erotic films as well as when they | ||
+ | decrease their feelings of sadness to sad films | ||
+ | * Additionally, | ||
+ | more intense feelings of sadness during the suppression condition, indicating that more | ||
+ | intense feelings of sadness required more OFC mediated inhibitory strength to suppress. | ||
+ | * In a direct comparison of using reappraisal to increase negative | ||
+ | affect (i.e. up-regulation) as compared to decrease negative affect (i.e. down-regulation), | ||
+ | found that the lateral OFC was more active when using reappraisal | ||
+ | to decrease as opposed to increase negative affect, and the DLPFC was more active when | ||
+ | using reappraisal to increase as opposed to decrease negative affect. This modulation of | ||
+ | amygdala activity occurred within 2 seconds of employing the reappraisal strategy | ||
+ | * DLPFC is involved in broad regulatory control of experience, | ||
+ | especially in bringing emotional representations on line, maintaining them, and | ||
+ | strengthening them, whereas the lateral OFC is involved in the inhibition of these | ||
+ | cortically represented feelings and images | ||
+ | * Inhibitory control in attitude regulation and memory | ||
+ | Goel and Dolan (2003) had people identify the validity of a set of logical arguments. | ||
+ | Some of the arguments were congruent with common beliefs about the world and some | ||
+ | were equally valid arguments but contradictory to common world beliefs. Using fMRI | ||
+ | they found that right OFC/VLPFC (BA 47, 45) was more active for correctly inhibiting | ||
+ | belief bias as compared to error trials in which the belief bias led to faulty reasoning and | ||
+ | the wrong conclusion. The VMPFC showed the opposite pattern. It was less active during | ||
+ | the correct inhibition of belief bias but more active when the a priori beliefs led to incorrect | ||
+ | reasoning (Goel and Dolan 2003). These findings illustrate that right OFC/VLPFC | ||
+ | activity was related to resistance to belief bias and suggests that this region may have | ||
+ | facilitated this resistance by inhibiting the influence of the a priori belief. | ||
+ | * They found that activity in the right lateral OFC was significantly correlated | ||
+ | with the amount that people felt that they had to control or suppress their initial | ||
+ | response to the concept. Interestingly, | ||
+ | which required the suppression of automatic responses were often those topics that had | ||
+ | both positive and negative qualities. Therefore these topics required more evaluation before | ||
+ | a judgement could be made (Cunningham et al. 2003, 2004), suggesting that, perhaps, the | ||
+ | process of evaluation suppresses the influence of emotional response on judgement. | ||
+ | * is not clear if there are distinct functions of the right versus left lateral | ||
+ | OFC/VLPFC during inhibition.Many inhibitory tasks show bilateral activations during | ||
+ | inhibition . Though it is tempting to claim that more emotional tasks, such as | ||
+ | emotion regulation, may employ right hemisphere systems , and | ||
+ | more cognitive tasks, such as the inhibition of proactive interference, | ||
+ | systems, this does not seem to be the case, since some cognitive tasks, such as | ||
+ | modulation of belief reason, and some emotional tasks, such as inhibiting a fearful face, show only left hemisphere involvement | ||
+ | |||
+ | There are several issues regarding the inhibitory mechanism that need to be resolved in | ||
+ | future research. First, it is not clear if there is a distinction between the inhibitory function | ||
+ | of the lateral OFC (BA 11, 12, 47) and the VLPFC, particularly the more superior | ||
+ | portions of BA 44, 45, in the frontal operculum. Many neuroimaging studies show | ||
+ | inhibitory activity that extends across both regions | ||
+ | |||
+ | * For example, the severity of depression correlates inversely with physiological activity in parts of the posterior lateral and medial OFC, consistent with evidence that dysfunction of the OFC associated with cerebrovascular lesions increases the vulnerability for developing the major depressive syndrome. | ||
+ | *There is abundant evidence for OFC involvement in motivational operations (8). Rapid stimulus-reinforcement association learning is implemented in the OFC (8), and the OFC is important for the alteration of stimulus–reward associations (9). The OFC appears to respond to the pleasantness of some stimuli (10, 11) as well as to the unpleasantness of other stimuli (8, 12–15). | ||
+ | | ||
+ | * anteromedial OFC +depressed versus the remitted phases of major depressive disorder to + correlated with the severity of depression. | ||
+ | * Effective antidepressant treatment | ||
+ | |||
+ | OFC | ||
+ | http:// | ||
+ | |||
+ | More precisely, the orbitofrontal cortex entails Brodmann areas 10, 11, and 47 (Kringelbach, | ||
+ | |||
+ | http:// | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | http:// | ||
+ | |||
+ | |||
+ | |||
+ | ====== Frontopolar cortex ====== | ||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | *anterior prefrontal, rostral prefrontal cortex and frontopolar prefrontal cortex are used to refer to the area in the most anterior part of the frontal cortex that approximates to or principally covers BA10. | ||
+ | *implicated in exploratory decision making | ||
+ | *it is the only prefrontal region that is predominantly (and possibly exclusively) interconnected with supramodal cortex in the PFC, anterior temporal cortex and cingulate cortex." | ||
+ | |||
+ | Subareas | ||
+ | BA 10 is divided into three sub-areas, 10p, 10m and 10r. 10p occupies the frontal pole while the other two cover the ventromedial part of the prefrontal cortex | ||
+ | |||
+ | |||
+ | http:// | ||
+ | *also termed ‘rostral prefrontal cortex (PFC)’, ‘anterior PFC’ or ‘frontopolar cortex’ | ||
+ | *prospective memory (PM) problems: ‘…it was as if he forgot to remember short- and intermediate-term goals…’ | ||
+ | * episodic memory tasks were associated with lateral area 10 activations. | ||
+ | * mentalizing tasks tending to provoke activations within caudal medial aspects of BA 10 , but paradigms that required the coordination of two or more activities (dual task, PM, etc.) were associated with very rostral activations within area 10 | ||
+ | * medial rostral PFC are involved in (i) focusing attention on perceptual versus self-generated information or (ii) mentalizing. | ||
+ | * rostral prefrontal cortex (PFC; approximating area 10) supports a cognitive system that facilitates either stimulus-oriented (SO) or stimulus-independent (SI) attending. | ||
+ | * medial area 10 support SO attending is the behaviour required to concentrate on current sensory input, whereas lateral area 10 support processes | ||
+ | *In particular, there is a functional dissociation between the anterior medial area 10, which supports processes required for SO attending, and the caudal medial area 10, which supports processes relating to mentalizing. | ||
+ | |||
+ | ====== DLPFC ====== | ||
+ | * DLPFC is important for the maintenance, | ||
+ | |||
+ | http:// | ||
+ | |||
+ | ====== VENTROLATERAL PFC ====== | ||
+ | In addition, right VLPFC activity was negatively correlated with | ||
+ | dorsal ACC activity, suggesting that the VLPFC was regulating neural activity related to | ||
+ | the social distress of being excluded. These findings converge with the idea that right | ||
+ | VLPFC mediates cognitive evaluation that mitigates neural activity associated with the | ||
+ | affective component of pain. | ||
+ | |||
+ | === Ventrolateral prefrontal cortex === | ||
+ | The ventrolateral prefrontal cortex mediates some of the cognitive responses to negative emotions. In particular, depression seems to activate the left ventrolateral prefrontal cortex, which in turn enables individuals to maintain their focus on a specific and consequential problem, minimizing distractions. Anxiety appears to activate the right ventrolateral prefrontal cortex, which enhances the vigilance of individuals to anticipated hazards. | ||
+ | |||
+ | The ventrolateral prefrontal cortex is sometimes called the inferior frontal cortex. This structure corresponds to Brodmann' | ||
+ | |||
+ | The difference between the ventrolateral prefrontal cortex and dorsolateral prefrontal cortex roughly aligns to the disparity between the ventral and dorsal pathways of the cortex, according to O' | ||
+ | |||
+ | The ventral pathways primarily terminate in the ventrolateral prefrontal cortex instead of the dorsolateral prefrontal cortex. Presumably, which features or attributes of the environment should be processed depends on the goals of individuals. The ventrolateral prefrontal cortex represents these goals and thus affects which features or attributes are extracted. That is, the ventrolateral prefrontal cortex biases or controls the ventral pathways. | ||
+ | |||
+ | The dorsal pathways primarily terminate in the dorsolateral prefrontal cortex instead of the ventrolateral prefrontal cortex. The dorsolateral prefrontal cortex represents complex relationships that can be applied, such as mathematical rules or other algorithms, to convert stimuli into responses. The dorsolateral prefrontal cortex, for example, may be able to retain a rule that was imposed a few minutes ago onto the dorsal pathway to ensure responses apply to these constraints. | ||
+ | |||
+ | O' | ||
+ | |||
+ | **Organization of the ventrolateral prefrontal cortex** | ||
+ | |||
+ | Many studies indicate that broad or abstract concepts, such as " | ||
+ | |||
+ | http:// | ||
+ | |||
+ | |||
+ | |||
+ | ====== MEDIAL PFC ====== | ||
+ | |||
+ | |||
+ | ====== VENTROMEDIAL PFC ====== | ||
+ | {{http:// | ||
+ | |||
+ | *implicated in the processing of risk, fear, and in decision making. | ||
+ | *Brodmann area 10.[2] However, not all sources agree on the boundaries of the area. | ||
+ | *Note that different researchers use the term ' | ||
+ | |||
+ | ==== Function ==== | ||
+ | *areas of the ventromedial cortex superior to the orbitofrontal cortex are much less associated with social functions and more with pure emotion regulation | ||
+ | *being associated with a decrease in cortisol levels | ||
+ | *Left lateral and medial orbitofrontal cortex areas were also measured to be highly active during guessing tasks. An increase in probabilistic scenario complexity was associated with orbitofrontal cortex activity level increase, therefore suggesting the special role that the ventromedial prefrontal cortex plays in decision making containing uncertainty. A study also indicated that patients with lesions in the ventromedial prefrontal cortex tend to have difficulties reacting to future consequences. | ||
+ | *The right half of the ventromedial prefrontal cortex was associated with regulating the interaction of cognition and affect in the production of empathic responses. Hedonic (pleasure) responses were also associations to orbitofrontal cortex activity level by Morten Kringelbach. This finding contributes findings suggesting ventromedial prefrontal cortex being associated with preference judgement, possibly assigning the ventromedial prefrontal cortex a key role in constructing one's self. Studies with PTSD also supported the idea that the ventromedial prefrontal cortex is an important component for reactivating past emotional associations and events, therefore essentially mediating pathogenesis of PTSD. Treatments geared to the inhibition of the ventromedial prefrontal cortex were therefore suggested for PTSD. The right half of the ventrolateral prefrontal cortex, being active during emotion regulation, was activated when participants were offered an unfair offer in a scenario. Specific deficits in reversal learning and decision-making have led to the hypothesis that the ventromedial prefrontal cortex is a major locus of dysfunction in the mild stages of the behavioural variant of frontotemporal dementia. | ||
+ | |||
+ | ---- | ||
+ | {{http:// | ||
+ | {{http:// | ||
+ | rodent | ||
+ | |||
+ | {{http:// | ||
+ | *vmPFC is homologous to rodent IL, whereas the dorsal regions of dACC are homologous to rodent PL | ||
+ | ---- | ||
+ | {{http:// | ||
+ | |||
+ | |||
+ | ====== ANTERIOR PREFRONTAL CORTEX ====== | ||
+ | http:// | ||
+ | *10p | ||
+ | *The results indicate a specific role for this region in integrating the outcomes of two or more separate cognitive | ||
+ | operations in the pursuit of a higher behavioural goal | ||
+ | |||
+ | The Truth about Lying: Inhibition of the Anterior Prefrontal Cortex Improves Deceptive Behavior | ||
+ | http:// | ||
+ | |||
+ | Abstract | ||
+ | Recent neuroimaging studies have indicated a predominant role of the anterior prefrontal cortex (aPFC) in deception and moral cognition, yet the functional contribution of the aPFC to deceptive behavior remains unknown. We hypothesized that modulating the excitability of the aPFC by transcranial direct current stimulation (tDCS) could reveal its functional contribution in generating deceitful responses. Forty-four healthy volunteers participated in a thief role-play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. During the interrogation, | ||
+ | |||
+ | *anterior prefrontal cortices (aPFCs; BA 9/10) were engaged during general deception, but that the right aPFC was more involved in lies that were well rehearsed and were part of a coherent story than in spontaneous, | ||
+ | *The main effect of generating untruthful responses revealed increased brain activity of the left dorsolateral prefrontal cortex (DLPFC; BA 8) and the right aPFC, whereas the left ventromedial PFC (BA 11) and Amygdala were associated with the process of deceiving the interrogator. Further analysis revealed that only the right aPFC was associated with both factors of deception, indicating that this region has a pivotal role in telling lies. | ||
+ | *4x6cm 1mA | ||
+ | |||
+ | |||
+ | ===== PREFRONTAL CORTEX FUNCTION ===== | ||
+ | |||
+ | http:// | ||
+ | |||
+ | However, the overall picture of prefrontal cortex function presented here | ||
+ | leads to a conceptualization of a cognitive processing hierarchy that proceeds along an | ||
+ | anterior to posterior gradient, from a) representations of stimulus value in the OFC and | ||
+ | rostral MPFC, to b) processing of internal goal and task-hierarchy representations in the | ||
+ | ALPFC, c) top-down biasing of stimulus representation in posterior cortices by DLPFC, | ||
+ | d) representation and updating of specific stimulus-response mapping rules in IFJ and | ||
+ | lateral premotor cortex, e) the motivated planning of overt motor behavior in pre-SMA | ||
+ | and cingulate motor areas, and f) the actual production of behavior in primary motor | ||
+ | cortex. This notion of hierarchy is present in related forms in several current models of | ||
+ | prefrontal function (e.g. Christoff & Keramatian, 2007; Koechlin et al., 2003). | ||
+ | Of course, any kind of processing hierarchy in prefrontal cortex does not proceed | ||
+ | in a truly linear fashion. One way to conceptualize cognitive control in the prefrontal | ||
+ | cortex is as proceeding from the result of evaluations about the value of various stimuli or | ||
+ | internal representations carried out in OFC. These valuations are then passed through the | ||
+ | dorsal anterior insula to lateral prefrontal cortex, wherein DLPFC selects representations | ||
+ | in posterior cortical regions that are task relevant and enhances their representation and/or | ||
+ | inhibits the representation of task irrelevant representations. When information needs to | ||
+ | be retrieved from LTM, the anterior portion of VLPFC is capable of initiating a | ||
+ | controlled retrieval process, and if there are multiple competing active representations | ||
+ | mid-VLPFC is recruited to select between them. The IFJ sets up S-R contingencies based | ||
+ | on the current context, and directs the development of motor plans in supplementary | ||
+ | motor cortex based on these contingencies. If additional processing on activated | ||
+ | representations is required, for example the solution of intermediate processing stages or | ||
+ | the completion of internally generated sub-goals, this is carried out by the RLPFC. | ||
+ | Finally, if an incorrect response is generated and detected prior to its execution, the right | ||
+ | IFG is brought online to inhibit the actual production of the response, and persistent | ||
+ | energization of the entire system is maintained by the DMJ. | ||
+ | |||
+ | |||
+ | ---- | ||
+ | Resting-State Functional Connectivity of the Medial Superior Frontal Cortex | ||
+ | {{http:// | ||
+ | |||
+ | ---- | ||
+ | |||
+ | Short frontal lobe connections of the human brain | ||
+ | | ||
+ | |||
+ | |||
+ | ---- | ||
+ | |||
+ | Sensory Pathways and Emotional Context for Action in Primate Prefrontal Cortex | ||
+ | |||
+ | | ||
+ | |||
+ | {{http:// | ||
+ | Connections between the prefrontal cortex and the amygdala. (A) Projections from posterior orbitofrontal cortex (pOFC) to the amygdala (magenta) target robustly the inhibitory intercalated masses in a unidirectional pathway. The pOFC also has bidirectional connections with the basal nuclei, where its connections overlap (brown) with sensory input (yellow) that reaches the amygdala from sensory association cortices. (B) Pseudo colored surface maps of the rhesus monkey brain show the strength of pathways from the amygdala that terminate in lateral (top) and orbital (bottom) prefrontal areas. The pOFC receives the strongest projections from the amygdala; the thickness of the arrows indicates pathway strength. AMY, amygdala; BL, basolateral nucleus; BM, basomedial nucleus; Ce, central nucleus; Co, cortical nuclei; IM, intercalated masses; La, lateral nucleus. | ||
+ | |||
+ | {{http:// | ||
+ | Schematic representation of direct projections from the amygdala to posterior orbitofrontal cortex, as well as indirect projections through the thalamic mediodorsal magnocellular (MDmc) nucleus, which is innervated by the amygdala. The terminations in the cortex show the predominance of direct amygdalar projections to the superficial layers and MDmc projections mostly to the middle cortical layers. The strong reciprocal projections from orbitofrontal cortex to MDmc and from posterior orbitofrontal cortex to the amygdala are not shown. TRN, thalamic reticular nucleus. | ||
+ | |||
+ | {{http:// | ||
+ | | ||
+ | |||
+ | |||
+ | ---- | ||
+ | {{http:// | ||
+ | {{http:// | ||
+ | {{http:// | ||
+ | |||
+ | |||
+ | ---- | ||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | Summary of amygdaloid outputs. Left: diagram of amygdaloid circuits involving the striatum pallidum medial thalamus and prefrontal cortex and output to the hypothalamus and brainstem. Right: diagram of areas of the cerebral cortex that receive axonal projections from the amygdala. The dark, medium, and lightly shaded areas represent high, medium, and low density of amygdaloid fibers. Modified from Amaral et al, 1992. | ||
+ | |||
+ | {{http:// | ||
+ | Anatomical circuits involving the medial prefrontal network (medial prefrontal network) and amygdala. Glutamatergic, | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | [[http:// | ||
+ | |||
+ | Functional brain circuits in pediatric bipolar disorder: cognitive circuitry shows the key link between the DLPFC and the caudate involved in attentional control and the connection between the VLPFC and the caudate/ | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | instantaneous correlation between the ROIs is shown as green lines. The distance between the nodes indicates the strength of their connection. The correspondence between ROI font colors and the RSNs is as follows. Red: default mode network (DMN), green: dorsal attention network (DAN), blue: hippocampal–cortical memory network (HCMN) and black: fronto-parietal control network (FPCN). The correspondence between ROI background colors and their anatomical location is as follows. Yellow: frontal cortex, pink: parietal cortex, blue: temporal cortex and green: cingulate cortex. | ||
+ | {{http:// | ||
+ | The reciprocal causal connections are shown as blue lines and the instantaneous correlation as green lines. The causal network formed by the blue lines represents the only strongly connected component in the entire network where in every ROI is mutually accessible causally by every other ROI. | ||
+ | |||
+ | |||
+ | {{http:// | ||
+ | paths with unidirectional influences | ||
+ | |||
+ | {{http:// | ||
+ | | ||
+ | |||
+ | {{http:// | ||
+ | dopaminergic-neuropeptide interactions in the social brain. This figure is a simplified account of neural circuits that are believed to contribute to the regulation of the social brain. Only a subset of interconnections between brain regions involved in processing emotions and social perceptions is shown. There are also noradrenergic and serotonergic outputs (from the locus coeruleus and the dorsal raphe, respectively), | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | {{http:// | ||
+ | Neural model of emotion regulation illustrating neural systems implicated in voluntary and automatic subprocesses of emotion regulation. (a) Feedforward pathway: medial prefrontal cortical system, including the OFC, subgenual ACG, rostral ACG, hippocampus and parahippocampus and MdPFC. (b) Feedback pathway: lateral prefrontal cortical system, including DLPFC and VLPFC. DLPFC, dorsolateral prefrontal cortex; MdPFC, dorsomedial prefrontal cortex; ACG, anterior cingulate gyrus; VLPFC, ventrolateral prefrontal cortex; OFC, orbital frontal cortex; hipp/ | ||
+ | These abnormalities, | ||
+ | |||
+ | |||
+ | {{http:// | ||
+ | {{http:// | ||
+ | |||
+ | |||
+ | {{http:// | ||
+ | |||
+ | ---- | ||
+ | The Neurocircuitry of Emotion Regulation | ||
+ | http:// | ||
+ | |||
+ | In this review, we examine the functional architecture underlying the regulation of fear, focusing on four different types of regulatory processes: extinction, cognitive emotion regulation, active coping, and reconsolidation. During extinction, fear is diminished through learning that a previously threatening stimulus no longer signals danger. Cognitive emotion regulation involves using various mental strategies to modify a fear response. In active coping, fear is regulated through the performance of behaviors that reduce exposure to a fear-evoking stimulus. Finally, a fear memory can be disrupted after it is recalled through pharmacological or behavioral manipulations that block its reconsolidation. Our understanding of the neurocircuitry underlying the control of fear stems from research across species clarifying the mechanisms by which we learn and modify emotional associations, | ||
+ | |||
+ | CS-conditioned stimulus | ||
+ | US-unconditioned stimulus | ||
+ | |||
+ | |||
+ | EXTINCTION | ||
+ | Extinction learning involves the formation of a novel stimulus-outcome association. The CS that earlier predicted danger now predicts safety. This new extinction memory does not erase or overwrite the memory for the original CS–US association. This is evidenced by the re-emergence of the CR in certain circumstances including a shift in context (renewal), unsignaled presentation of the US (reinstatement), | ||
+ | |||
+ | neural mechanisms of fear conditioning across species indicate that the amygdala has a critical function in the acquisition, | ||
+ | |||
+ | This body of research suggests that interaction between the amygdala, the ventromedial prefrontal cortex (vmPFC), and the hippocampus supports the acquisition, | ||
+ | |||
+ | Although the amygdala seems to be critical for the acquisition of extinction learning, convergent evidence suggests that the vmPFC is necessary for the retention and recall of extinction. In line with the well-documented observation in human beings and primates that damage to the PFC leads to perseverative behavior | ||
+ | |||
+ | administration of an NMDA antagonist within the vmPFC all impair retrieval of extinction suggest that the plasticity in this region supports extinction consolidation | ||
+ | |||
+ | After extinction, contextual information has a critical function in determining whether the original fear memory or the new extinction memory should control fear expression . Evidence suggests that hippocampal projections to the vmPFC and the amygdala mediate the context-dependent expression of extinction | ||
+ | |||
+ | Furthermore, | ||
+ | |||
+ | studies have also observed increased vmPFC activation during extinction retrieval | ||
+ | |||
+ | hypocampus may mediate context-dependent extinction recall through connections with the vmPFC | ||
+ | |||
+ | Finally, a recent study reported that mice lacking the serotonin transporter gene show marked deficits in extinction retention (Wellman et al, 2007). As human beings with the low-expressing short allele variant of this gene exhibit decreased functional connectivity between the vmPFC and amygdala (Pezawas et al, 2005), this suggests a possible genetic basis for individual differences in extinction learning, as well as a potential risk factor for the development of anxiety disorders. | ||
+ | |||
+ | COGNITIVE REGULATION STRATEGIES | ||
+ | Many different cognitive strategies can be used to regulate emotion, including reappraisal, | ||
+ | |||
+ | cognitive regulation techniques often require the active engagement of the participants | ||
+ | |||
+ | reappraisal of negative scenes, as opposed to just attending to them, resulted in increased activation of both dorsolateral PFC (DLPFC) and ventrolateral PFC (VLPFC) regions along with dorsal anterior cingulate, and decreased activation of a region of the orbitofrontal cortex and the amygdala | ||
+ | |||
+ | It was proposed that underlying the reappraisal of negative effect, the engagement of the DLPFC may be linked to executive control processes required in the online manipulation of the interpretation of scenes, and the decrease of amygdala activation may reflect the cognitive control of subcortical mechanisms linked to the representation of negative emotional value | ||
+ | |||
+ | studies consistently report decreased amygdala activation and increased activation of the DLPFC and/or VLPFC, along with some involvement of medial PFC (mPFC) regions. | ||
+ | |||
+ | In this model, the DLPFC is involved in the effortful manipulation or interpretation of the stimulus and the VLPFC may have a function in the selection of emotion interpretation . The changes observed in the amygdala are the result of the top down modulation of the emotional meaning of the stimulus. One important aspect of this model is that the DLPFC does not project directly to the amygdala | ||
+ | |||
+ | Instead its influence on the amygdala is likely mediated by ventral and mPFC regions that have stronger connections with the amygdala . Although this model of emotion regulation is somewhat speculative | ||
+ | |||
+ | ACTIVE COPING | ||
+ | parts of amygdala | ||
+ | |||
+ | RECONSOLIDATION | ||
+ | During this consolidation period, it is possible to disrupt the formation of the memory, but once this time window has passed, the memory may be modified or inhibited, but not eliminated. However, recent studies support an alternative view of memory in which every time a memory is retrieved, the underlying memory trace is once again labile and fragile, requiring another consolidation period called reconsolidation. This reconsolidation period allows another opportunity to disrupt the memory. | ||
+ | |||
+ | As outlined above, extinction training usually results in two competing memory traces, a CS–US trace that competes for expression with a CS–noUS trace. As both traces exist, fear can return with standard extinction training, as different circumstances favor the expression of one trace over another (Bouton, 2004). However, the study by Monfils et al (2009) suggests that extinction training during the reconsolidation window results in an alternative memory representation. When extinction learning occurs during the time period in which the original CS–US trace is labile, this original trace may be significantly altered to incorporate the CS–noUS learning before re-storage. The result is either an alternative or combined memory trace representing the significance of the CS. Importantly, | ||
+ | |||
+ | {{http:// | ||
+ | Model for the neurocircuitry of fear regulation in humans through extinction, cognitive regulation, active coping, and reconsolidation. A network of structures including the amygdala, hippocampus, | ||
+ | |||
+ | |||
+ | ---- | ||
+ | |||
+ | {{http:// | ||
+ | |||
+ | |||
+ | ---- | ||
+ | |||
+ | We show that activity in right rostrolateral prefrontal cortex (rlPFC) satisfies three constraints for a role in metacognitive aspects of decision-making. | ||
+ | |||
+ | *These cognitive and motor systems, respectively, | ||
+ | |||
+ | ventral prefrontal cortex and the ventral basal ganglia, has been implicated in encoding expected rewards | ||
+ | |||
+ | |||
+ | |||
+ | |||