What is Anterior Cingulate Cortex? its structure, function and disorder’s related to anterior cingulate cortex?

Author: Durga Naik

What is Anterior Cingulate Cortex (ACC)?

The human brain is a detailed roadmap of complex circuitry and essential neuron connectivity. Every part of the brain has its own unique responsibilities that determine who we are and how we function. The anterior cingulate cortex (ACC)  is responsible for a host of cognitive functions, including emotional expression, attention allocation, and mood regulation.

It functions similarly to two brain regions found in the centre of your brain. Its affiliation with the limbic system-which regulates emotions and memory has made it most well-known. The prefrontal cortex, which aids in decision-making, the amygdala, which is involved in emotions, and reward centres are just a few of the brain regions that the cingulate cortex interacts with. The hippocampus and amygdala share neuronal pathways with the cingulate cortex, which may play a role in processing emotionally charged events and forming long-term memories, respectively. Together, these components function in key brain circuits that enable us to feel emotions, make decisions, and move our bodies.

STRUCTURE OF ANTERIOR CINGULATE CORTEX

The corpus callosum, which connects the two halves of the brain, is surrounded by the cingulate cortex, a region of the brain. It consists of the gray matter surrounding the margins of a groove known as the cingulate sulcus and the cingulate gyrus. Imagine it as a belt that begins beneath the corpus callosum’s front portion, wraps around it, and then rises above it to the back, ending at an area known as the isthmus. The Para hippocampal gyrus, a different region of the brain, is connected to this isthmus. A groove divides the cingulate gyrus from the corpus callosum below and from the superior frontal gyrus above, two different brain regions. The frontal, temporal, parietal, and occipital lobes surround the cingulate cortex, which is located deep within the brain and is essential for a number of processes including emotion regulation, decision-making, and memory processing.

The anterior cingulate cortex (ACC), midcingulate cortex, posterior cingulate cortex (PCC), and retro splenial cortex are the four primary regions of the brain’s cingulate cortex. Smaller components of the ACC include the dorsal anterior cingulate cortex (dACC) and perigenual anterior cingulate cortex (pACC). The pACC deals with emotions and regulates our body’s reactions to them, such as an elevated heart rate or perspiration in response to anxiety. Decisions are made by the dACC, particularly when it comes to incentives. Furthermore, the cingulate motor regions (CMAs) facilitate movement coordination in response to external stimuli (e.g., sounds and sights) as well as internal stimuli (e.g., emotions). They collaborate closely with other brain regions to ensure that our bodies move naturally and sensibly.

The vast neuronal networks that the cingulate cortex shares with other brain regions indicate that it functions as a sort of hub for emotions, sensations, and actions. The connections between these pathways and the orbitofrontal cortex, basal ganglia, and insula-which collectively constitute the brain’s reward centres-indicate that some of them are engaged in motivational processing. Moreover, the lateral prefrontal cortex, which is engaged in learning, working memory, and executive control, receives connections from the cingulate cortex. The spinal cord, frontal eye fields, and main and supplementary motor cortices are some of the motor areas that the cingulate cortex is connected to, and these connections may play a significant role in motor control. Furthermore, damage to any part of the brain network responsible for orienting attention-the cingulate cortex, frontal, and parietal lobes is known to result in hemineglect.

DIVISIONS OF THE ANTERIOR CINGULATE CORTEX

The ACC is split into dorsal (caudal) and ventral (rostral) subdivisions:

Dorsal: The dorsal subdivision is in charge of cognitive control. The dorsal ACC subregion connects to the prefrontal cortex, parietal cortex, motor areas, and eye fields responsible for interpreting stimuli—like top-down and bottom-up processing.

Ventral: The ventral ACC is connected to the limbic system and is in charge of emotional response and reactivity. This subdivision includes the anterior insula, amygdala, hippocampus, and hypothalamus, all of which play a role in processing emotional information.

The ACC also has connections to the orbitofrontal cortex and ventral striatum, which manages the brain’s reward system.

FUNCTIONS OF THE ANTERIOR CINGULATE CORTEX

The ACC is responsible for numerous functions, such as:

• Expression of emotions: Our ability to modulate our emotions is greatly aided by the ACC. The medial prefrontal cortex is one of the brain regions that can be affected by negative emotional stimuli. The prefrontal cortex and anterior cingulate cortex are essential for controlling mood and emotional response. Specifically, the ACC addresses how we manage or steer clear of unpleasant emotions. According to certain neuroimaging studies, those who suffer from addiction exhibit below-average activation in brain processing. This suggests a connection between those who use drugs or engage in maladaptive behaviours as a coping mechanism for unpleasant feelings and those who have abnormalities in the ACC, such as lesions or damage.
• Emotional awareness: Research published in the Journal of Neuropsychology and Clinical Neurosciences suggests that people with high ACC activation may have better emotional awareness. On the other hand, people with social cognition impairments, such as schizophrenia, have demonstrated abnormalities in their ACC’s functionality, which may be linked to symptoms of disconnection, aberrant salience attribution, and difficulty identifying others’ emotions or determining their emotional reactions. Seasonal affective disorder (SAD), a type of major depressive disorder (MDD), may also exhibit disturbances in the dynamic of their ACC processes.
• Decision-making: The orbitofrontal cortex and ACC are directly related, which means that they have an effect on reward-based decision-making. Using the ACC, we can evaluate several courses of action and decide which will result in the best or most desired situation. This function is particularly crucial for adaptation because it enables our brains to make snap judgments that may be essential to our survival or immediate benefit.
• Pain management: Research on functional connectivity using functional magnetic resonance imaging (fMRI) has revealed that an individual’s ACC signal intensity increases in response to physical pain. Rather of controlling how we perceive pain; this cortical region controls our emotional reactions to it.
• Attention allocation: By assisting our brains in weighing the pros and cons of our decisions, the ACC is also the part of the brain that helps us choose which events or tasks receive priority attention. From a psychiatric perspective, individuals with mental illnesses like attention-deficit hyperactivity disorder (ADHD), which is a malfunction in the attention-allocation process, can have anomalies within the ACC.
• Anticipation: The ACC experiences an increase in blood flow as a result of cognitive activities such as anticipation. According to certain fMRI studies, individuals who were given instructions on a certain task and actively prepared for it showed an increase in cerebral blood flow to the anterior cingulate cortex (ACC), indicating that region of the brain has a role in anticipatory anxiety.
• Error detection: One of the key features of the ACC is conflict monitoring, which enables us to keep an eye out for inconsistencies in the way we process information and identify the situations that are most likely to result in errors. A subregion of the ACC called the anterior cingulate gyrus enables us to identify irregularities in our own and other people’s behaviour during social encounters.
• Autonomic nervous system response: The human brain’s autonomic nervous system (ACC) is activated in response to stressors, and it helps to control heart rate and blood pressure.

DAMAGE TO ANTERIOR CINGULATE CORTEX

Numerous mental, emotional, and bodily processes depend heavily on the anterior cingulate cortex. Damage to this system can therefore result in a variety of issues, including executive failure, lack of empathy, poor decision making, flat affect (lack of emotion), autonomic dysfunction, and more. Thankfully, with the correct rehabilitation strategy, many of these deficits can be addressed. Cognitive rehabilitation, for example, can be provided by an occupational or speech therapist.

DISORDERS RELATED TO ANTERIOR CINGULATE CORTEX

Numerous studies in cognitive and neurocognitive processes focus on the cingulate gyrus. For example, Alzheimer’s illness, anxiety disorders, addiction, depression, bipolar disorder, and schizophrenia have all been linked to it. When comparing patients with schizophrenia to controls, there are variations in the anterior cingulate gyrus. Patients with schizophrenia were shown to have smaller anterior cingulate gyruses. It has been discovered that individuals with schizophrenia have a reduced volume of gray matter in the front cingulate gyrus. Alzheimer’s disease (AD) and behavioural variation frontotemporal dementia (by FTD) are both characterized by early atrophy of the cingulate cortex, with degeneration of the anterior cingulate region becoming increasingly recognized as a good predictor of by FTD.

The ACC is a key “hub” in neural networks of cognitive activities connected to addiction, such as emotion, motivation, cognitive inhibition, and decision-making. The hallmark of substance use disorder (SUD) is compulsive use of addictive drugs, which has a significant negative influence on society at large as well as the medical community.  Recent discoveries on the anterior cingulate cortex (ACC) point to the possibility of treating SUDs with neuromodulation that targets the ACC.

CONCLUSION

An important part of the brain involved in many different processes, such as emotion regulation, pain processing, cognitive control, and decision-making, is the anterior cingulate cortex (ACC). The ACC is essential for coordinating reactions to different stimuli and settings because of its complex connections with other brain regions. This helps us adapt to changing environments and make appropriate behavioural decisions. The importance of the ACC in maintaining mental health and wellbeing is demonstrated by the fact that dysfunction in the ACC has been linked to a wide range of neuropsychiatric illnesses, including anxiety, depression, schizophrenia, and chronic pain syndromes. Overall, the ACC is a primary target of study because it acts as a vital hub for combining data from various brain networks and coordinating complicated activities.

REFERENCES

• Anterior Cingulate Cortex: Unique Role in Cognition and EmotionWhat is Anterior Cingulate Cortex.

• Lavin C, Melis C, Mikulan E, Gelormini C, Huepe D, Ibañez A. The anterior cingulate cortex: an integrative hub for human socially-driven interactions. Frontiers in neuroscience. 2013 May 8;7:64.

• what is Cingulate Gyrus?

• Primate anterior cingulate cortex: Where motor control, drive and cognition interface

• The anterior cingulate cortex: an integrative hub for human socially-driven interactions