Difference between revisions of "ACC"

Latest revision as of 01:31, 15 January 2015

The anterior cingulate cortex (ACC) is the frontal part of the cingulate cortex, that resembles a "collar" form around the corpus callosum, the fibrous bundle that relays neural signals between the right and left cerebral hemispheres of the brain. It consists of Brodmann areas 24, 32 and 33. It 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^[1] and emotion.^[2][3]. ACC gyrus is involved in learning social values^[4]. ACC is also necessary for an appraisal of the energetic cost versus benefits of actions, and a preference to expend effort to achieve a goal.

ACC sulcus may be required for learning of action values^[5]. Similar regions in ACC have also been shown to encode decision uncertainty^[6]

In decision making it is thought to detect conflicts between two deductions^[7][8][9] and evaluating the rewards of actions^[10]. On the integration of these finding please read this article.D1 (dopamine 1) receptor blockade in ACC reduces preference for expending effort for rats^[11].

Medial surface of left cerebral hemisphere, with anterior cingulate highlighted.

In order to resolve an emotional conflict the rostalACC inhibits the amygdala (or FFFF mechanism)^[12]. This is strengthing by the findings that in panic disorder, the volume of the the ACC is reduced, ^[13] . When the ACC (ACcd) has deficient in activation, there seem to be more impolsivity in ADHD compered to control group^[14]. When anticipating pain, women domnstrate more activation of the ACC^[15].

It seems that LC-NE relese Norepinephrine to ACC, which then elvate wakeness. The ACC send signals to the LC, to maintain wakeness while new stimules are precived^[16]

There is a link between ACC activation and pupil size^[17]

reduction in right ACC volume correlates to aggression and defiance^[18]

dorsal ACC

dACC

Hypotheses about its function include guiding reward-based decision making^[19], monitoring for conflict between competing responses^[20] and predicting task difficulty^[21]. Precise mechanisms of dACC function remain unknown. It was found that dACC is involved in adapting behaviour.^[22], and help focus attention on the desired option, when conflict arise^[23].

It is thought that the dorsal ACC is primarly involved in cognitive processing^[24]. It is part of the learning mechanism, that learn the positive and negative outcomes of actions in neutral tasks^{[25][26][27][28]} and with correlation with rostral ACC, it is involved in emotional learning. It is also a reward mechanism, that gives "globals enrgizing factor", to actions that in the past seems to be rewarding^[29]. Rats with lisions in the ACC, prefer less effortful mission with less reward, to tasks with more effortful with more reward^[30].The ACC motivation mechanism is dependent on dopamin^[31][32].

Hypothesis: The Meutation in Dopamin receptor D2 may lower the amount of dopamin recived by the ACC, thus it may be the cause that make people with Atention Deficit Disorder (ADD), have lack of motivation to engage in effortful actions and decision making.

A Role for the Human Dorsal Anterior Cingulate Cortex in Fear Expression, 2007 - dACC has a major role in fear expression. When electrode stimulus was introduced to the dACC during head operations, patients reported high level of anxiety, where as when the regions was removed, anxiety symptoms were reduced^[33]. See also the page on fear.

Dorsal ACC decision making system

rostral ACC

rACC

Also called ventral ACC

It is thought that rostral ACC id involved in emotional processing^[34]. Sadness enhances the experience of pain via neural activation in the anterior cingulate cortex and amygdala^[35].The Rostral Anterior Cingulate Cortex Modulates the Efficiency of Amygdala-Dependent Fear Learning^[36].

It seems that rostral ACC is in the side of the critique^[37] and have negative feedback on selection of actions. it is highly active in depression^[38]. rACC is correlated with error detection^[39][40]. It is used in emotional conflicts^[41] but not with neutral conflicts^[42][43][44].

rACC is negatively correlated with amygdala activity in conflict resolution tasks. it is suggested that the rACC down-regulate the amygdala^[45]. (And may reduce anger or anxiety?)

Liberals and ACC

Liberals have higher ACC gray volume^[46]. ACC is connected to conflict resultion (rACC to social conflict and dACC to non-social conflict). Reward valence modulates conflict-driven attentional adaptation in the ACC^[47]. ACC appear to encode negatively-valenced components, such as cost or effort^[48]. Greater liberalism was associated with stronger conflict-related anterior cingulate activity, suggesting greater neurocognitive sensitivity to cues for altering a habitual response pattern, while conservatives have larger volume of right amygdala^[49][50] As well as more avodience of doing, due to the highten percived costs that the higher volume of the ACC can cause^[51].

The ACC is important for responce time, therefore it was suggested that the ACC is related to "global energizing factor"^[52]

ACC is enlarged in people with large social networks.

Aggresivnce and ACC

Childrens with aggressive problems (disruptive behavior disorders) show reduced activity in the ACC^[53].

Further readings

• An article in a book about theories on the functions of dorsal ACC (2011).
• A Research on ACC and conflicit resolution (2004).
• A paper on A paper on ACC and atteintion defliction on pain (2002).
• An importan article about the social and non-social brain mechanism in autism^[54].

Other close areas

• Theory of cognitive dissonance^[55]

References