Anterior Cingulate Cortex

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The anterior cingulate cortex plays a crucial role in complex neurological processes. This brain region is pivotal for solving problems and navigating the social world effectively. So, where is the anterior cingulate cortex located, and what are its principal functions?

The anterior cingulate cortex (ACC) is part of the cerebral cortex and envelopes the corpus callosum. The ACC is involved in high-level cognitive functions like decision-making and problem solving, and psychological functions relating to social interaction, emotion, and empathic responses.

Our capacity for rational and ethical behavior is heavily influenced by the activity of the ACC. If you’re interested in the anatomy and functions of the ACC, this post provides some foundational information about this fascinating neurological structure. 

Anatomy Of The Anterior Cingulate Cortex

The anterior cingulate cortex (ACC) is the front portion of the cingulate cortex (or limbic lobe), a horseshoe-shaped structure near the brain center. The location of the ACC is below the frontal and parietal lobes and surrounding the corpus callosum (a dense layer of nerve fibers lying underneath the cerebral cortex).

The ACC is a small but significant brain region involved in highly complex neurological processes. A distinguishing feature of the ACC is its dense concentration of spindle cells. Spindle cells are an evolutionarily recent kind of neuron only found in humans, the great apes of Africa, elephants, and cetaceans. 

These neurons in the ACC are active when figuring out solutions to complex problems. The abundance of spindle cells in the ACC reflects its powerful and sophisticated processing potential.

The ACC consists of three Brodman areas, which are brain regions defined by their distinct cellular configurations (called cytoarchitecture). These three regions of the ACC are BA24, BA32, and BA34.

However, it is more common to divide the anatomy of the ACC into its dorsal (upper) and ventral (lower) portions. The dorsal ACC is principally involved in cognition, while the ventral section of the ACC is associated with aspects of psychology and emotion.

The Dorsal ACC

The dorsal ACC (or dACC for short) is principally associated with high-level cognition.

The dACC connects with the following regions of the cerebral cortex:

  • prefrontal lobe,
  • parietal lobe,
  • motor system,
  • frontal eye field.

The prefrontal lobe (cortex) is located above the dACC and is responsible for executive functions in the brain, including analysis, evaluation, planning, and motivation. The dACC also connects to the parietal lobe (behind the prefrontal lobe), a region of the cerebral cortex involved in processing sensory stimuli.  

The dACC also connects to the motor cortex or system, a region of the cerebral cortex responsible for performing voluntary movement of the body. Finally, the dACC is joined to the frontal eye field, which is involved in the processing of visual stimuli.

Due to its position in the brain, the dACC plays a critical role in delegating particular areas of the brain to perform specific tasks. Similarly, the dACC is intimately involved in interpreting sensory information received from the physical environment.

The Ventral ACC

The ventral ACC (vACC) is on the underside of the ACC, directly above the corpus callosum. This part of the ACC is primarily involved in the perception, evaluation, and experience of emotion, most notably in the context of tasks requiring concentrated effort. The vACC connects with the following parts of the brain:

  • hippocampus,
  • hypothalamus,
  • anterior insula,
  • nucleus accumbens,
  • amygdala.

The hippocampus lies below the vACC and is part of the limbic system. One of the primary roles of the hippocampus is integrating information from short and long-term memory.

The hypothalamus is another part of the limbic system connected to the vACC. This pair of tiny round-shaped neurological structures are responsible for vital activities such as mediating between the endocrine and central nervous systems.

The vACC also connects to a section of the hypothalamus called the nucleus accumbens, which is part of the brain’s reward system and participates in functions associated with motivation and behavioral reinforcement.

The amygdala is another crucial part of the limbic system connected to the vACC. There is one of these structures on the side of each hippocampus. The amygdala is activated when we experience basic emotions like fear, anger, and pleasure, and it is also involved in binding individual memories with particular emotions.

The vACC interacts directly with the anterior insula cortex, an area deep inside the brain. This area of the brain is involved in the subtle psychological mechanics of emotion and consciousness, as well as cruder physical processes such as the experience of pain and hunger.

Functions Of The Anterior Cingulate Cortex

The ACC performs a unique integrating role in the brain because, as we saw above, it connects and mediates between parts of the brain responsible for both cognitive and psychological-emotional processes. Let’s look more closely at a few of the critical neurological functions the ACC participates in:

  • decision-making,
  • reward-based learning,
  • consciousness,
  • social interaction,
  • empathy responses,
  • experiencing pain.

Decision-Making

The ACC is a component of the brain’s decision-making network with the prefrontal and parietal cortex. As part of the decision-making network, the ACC is responsible for detecting cognitive and behavioral errors. The ACC is also involved in interpreting and learning from those errors to inform future decisions.

The rostral (front) section of the ACC plays a vital role in decision-making through its interaction with the limbic system. This central rostral ACC receives information from the limbic structures about the differences between the anticipated and actual results of a particular decision.

In the decision-making process, the ACC evaluates and assigns significance (or value) to each of the potential decision alternatives.

After processing this information, the ACC sends signals to the dorsolateral prefrontal cortex to initiate a coordinated behavioral response (in this case, taking appropriate action in response to the outcomes of the decision).

Reward-Based Learning

The ACC is fundamental to the learning function, which is closely linked with the ACC's role in decision-making processes. Reward-based learning is a prominent neurological theory that posits that the brain engages with, retains, and applies new information through a process of rewards and errors or costs (such as effort).  

The rostral ACC and dorsal ACC detect and evaluate signals about rewards (successes) and errors linked to past and present actions and events. These areas of the ACC store the information from this learning process as a basis for making future decisions.

The rostral ACC is involved primarily in our emotional (affective) response to mistakes. In contrast, the dACC participates in our cognitive responses to those errors. As a result, higher dACC activity is associated with a decrease in errors and an increase in success during complex learning processes. 

Mental effort is a crucial cost variable in reward-based learning theory and is directly affected by the ACC. The ACC evaluates the degree of effort (attention or concentration) required to learn new information or behavior versus the potential rewards of that effort and is involved in applying and maintaining mental effort.

The relation between the ACC and learning effort means this region of the cingulate cortex is closely involved in challenging learning scenarios like initiating and establishing new behavioral patterns.

Consciousness

Consciousness is a slippery and nebulous phenomenon in the fields of neurology and psychology. Nonetheless, the phenomenon of consciousness is fundamental to our understanding of the brain and its relation to conscious awareness. 

Scientific research suggests that the ACC is deeply involved in our experience of consciousness, particularly with respect to emotional awareness. Studies of individuals with high levels of emotional intelligence demonstrate that the ACC region of their brains became active when they viewed emotionally-intense audio-visual content.

One hypothesis proposes that the ACC plays a pivotal part in human free will. For instance, the renowned scientist Francis Crick posited that the ACC might be the physical basis for our ability to think and act for ourselves.

Social Interaction

The ACC is vital for our ability to interact effectively with other people. The anterior region of the cingulate cortex is part of the neural pathways that detect and interpret social signals.

For example, the dACC is active when the brain processes experiences of exclusion or marginalization from a group. The significance of the dACC in the neurology of social exclusion is attested to by the fact that individuals suffering from depression generally have excessively elevated dACC activity.

The anterior region of the cingulate cortex also plays an essential role in social cognition, which refers to the affective aspect of decision-making. Activation of the ACC occurs when individuals make decisions that require evaluating and balancing conflicting social (emotional) and economic (rational) factors.

Furthermore, the ACC facilitates our ability to make sense of social context and enables us to respond appropriately based on that analysis.

The ACC helps us decode the unwritten nuances of social context through its involvement in the integrated processing of signals specific to the context and generalized information that is not contingent on that context.

Empathy Responses

The ACC is fundamental to empathy. Empathy is a complex psychological phenomenon with a cognitive and an emotional dimension, which is why the ACC becomes activated during the experience of empathy.

The ACC’s involvement in empathy-related responses to pain is well-documented. Studies demonstrate that activity in the ACC increases when we see other people experiencing physical pain.

The ACC is part of the pain network, which is responsible for our experience of pain. Certain areas of this neural network are active when we experience an empathic response to another person's pain, namely the:

  • cerebellum,
  • rostral ACC,
  • brain stem,
  • bilateral anterior insula.

When we see someone else in physical pain, these areas of the pain network receive and process that information and send signals to other parts of the brain to trigger a cognitive awareness and emotional experience of empathy.

Experiencing Pain

The ACC is not only involved in our brain’s response to other peoples’ pain but it is also involved in our personal experience of pain.

This role results from the ACC’s connection with parts of the pain network responsible for registering pain in the body. This section of the pain network consists of:

  • caudal ACC,
  • sensorimotor cortex,
  • posterior insula.

The ACC is responsible for the emotional dimension of our pain experience rather than the physical sensations of it. This effect is partly due to the ACC’s close interaction with the cortical area.

Scientific studies show that increased pain intensity causes a proportionate increase in the input signals received by BA24 of the ACC.

Potential Consequences Of ACC Dysfunction

A dysfunctional ACC can lead to a diverse range of cognitive and mental health challenges because it plays a role in multiple high-level neurological processes. Damage in the form of lesions is the most common cause of ACC dysfunction.

If the ACC is not functioning effectively, individuals can have difficulty detecting and correcting errors when learning and making decisions.

People with damaged ACCs may also experience challenges when attempting to sustain their focused attention for long periods and are easily distracted by conflicting stimuli. 

Studies of individuals diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) show that these research participants have excessively-low levels of activity in their dACC region. On the other extreme, Obsessive Compulsive Disorder (OCD) is associated closely with depleted glutamate levels in the ACC.

Emotional imbalance is another symptom that accompanies an ACC that is not functioning optimally. For instance, people with mood disorders like depression and post-traumatic stress generally have elevated activity in the cingulate gyrus of the ACC.

Individuals may also encounter challenges when the connection between their ACC and the rest of their brain is compromised.  This disconnection can undermine the executive functions of their brains, which is closely associated with ineffective self-control and a predisposition towards risk-taking behavior.

Conclusion

The anterior cingulate cortex (ACC) is responsible for numerous critical neurological processes. It plays an intermediary role, integrating parts of the brain responsible for high-level cognitive functions with regions of the brain primarily responsible for the emotional aspects of human experience.

The ACC is connected to neural pathways implicated in functions as diverse as decision-making, learning, social interaction, empathy, and the emotional experience of pain. Consequently, damage to the ACC is associated with psychological and social challenges like depression, learning difficulties, ADHD, and risk-taking behavior.

References

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3647221/

https://www.sciencedirect.com/topics/neuroscience/spindle-neuron

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116891/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5755235/

https://pubmed.ncbi.nlm.nih.gov/20336686/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4017137/

https://pubmed.ncbi.nlm.nih.gov/18465373/

https://www.pnas.org/doi/10.1073/pnas.012470999

https://pubmed.ncbi.nlm.nih.gov/23713508/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC193981/

https://pubmed.ncbi.nlm.nih.gov/15795139/

https://link.springer.com/article/10.3758/s13415-017-0502-3

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4942880/

Reference this article:

Practical Psychology. (2022, August). Anterior Cingulate Cortex. Retrieved from https://practicalpie.com/anterior-cingulate-cortex/.

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