Anterior cingulate cortex

The anterior cingulate cortex (ACC) is the frontal part of the cingulate cortex that resembles a 'collar' surrounding the frontal part of the corpus callosum. It consists of Brodmann areas 24, 32, and 33.Medial surface of human cerebral cortex - gyriAnterior Cingulate Cortex of monkey (Macaca mulatta). The anterior cingulate cortex (ACC) is the frontal part of the cingulate cortex that resembles a 'collar' surrounding the frontal part of the corpus callosum. 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. It is also involved in certain higher-level functions, such as attention allocation, reward anticipation, decision-making, ethics and morality, impulse control (e.g. performance monitoring and error detection), and emotion. The anterior cingulate cortex can be divided anatomically based on cognitive (dorsal), and emotional (ventral) components. The dorsal part of the ACC is connected with the prefrontal cortex and parietal cortex, as well as the motor system and the frontal eye fields, making it a central station for processing top-down and bottom-up stimuli and assigning appropriate control to other areas in the brain. By contrast, the ventral part of the ACC is connected with the amygdala, nucleus accumbens, hypothalamus, hippocampus, and anterior insula, and is involved in assessing the salience of emotion and motivational information. The ACC seems to be especially involved when effort is needed to carry out a task, such as in early learning and problem-solving. On a cellular level, the ACC is unique in its abundance of specialized neurons called spindle cells, or von Economo neurons. These cells are a relatively recent occurrence in evolutionary terms (found only in humans and other primates, cetaceans, and elephants) and contribute to this brain region's emphasis on addressing difficult problems, as well as the pathologies related to the ACC. 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 consists of an arrow pointing to the left or right, which is flanked by two distractor arrows creating either compatible (<<<<<) or incompatible (>><>>) trials. Another very common conflict-inducing stimulus that activates the ACC is the Stroop task, which 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. Many studies attribute specific functions such as error detection, anticipation of tasks, attention, motivation, and modulation of emotional responses to the ACC. The most basic form of ACC theory states that the ACC is involved with error detection. Evidence has been derived from studies involving a Stroop task. However, ACC 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 more competitive than others. They found that for more competitive stimuli ACC activation was greater. A similar theory poses that the ACC’s primary function is the monitoring of conflict. In Eriksen flanker task, incompatible trials produce the most conflict and the most activation by the ACC. Upon detection of a conflict, the ACC then provides cues to other areas in the brain to cope with the conflicting control systems.