Cingulate Cortex

Many people wonder about the largest part of the brain associated with memory and emotions. They do know that hypothalamus and hippocampus are the areas associated with these processes. But do often do not remember the cingulate cortex, the largest area of brain dedicated to this purpose.

The cingulate cortex is a C shaped area of the brain
associated with memory, sleep, emotions, and behavior. It is considered to be a
part of the limbic system.

In this article, we will study in detail the structure, connections and blood supply of the cingulate cortex. We will also discuss the functions of the cingulate cortex. In the end, we would mention the clinical significance of this important structure present in the brain.

Anatomy

Location

The cingulate cortex is present on the medial side or inner side of the cerebral cortex. It consists of cingulate gyrus and its continuation into the cingulate sulcus. It lies just above the corpus callosum on the medial side of the brain.

Although, it does not fall into any of the typical frontal, parietal, occipital or temporal lobe division; but it is considered to be a part of limbic lobe. It is because it is an essential part of the limbic system.

Structure

The cingulate cortex is composed of grey matter and is
divided into two parts, the anterior cingulate cortex and the posterior cortex.

Anterior Cingulate Cortex

The anterior cingulate cortex comprises of the Brodmann area 24,33 and 34. Anteriorly, it continues as subgenual area which is located just below the genu of the corpus callosum. This part of the cortex is partially located in the cingulate gyrus and partially in the cingulate sulcus.

Some scientists further divided it into two parts; perigenual cortex, located along the genu of the corpus callosum, and midcingulate cortex. The former is associated with the cognitive functions and the later is associated with the emotional functions.

The cellular structure of this area is agranular. Special type of neurons are present in the anterior cingulate cortex. These are called the spindle cells.

Posterior Cingulate Cortex

The posterior cingulate cortex comprises the Brodmann area 23 and 31. It comprises of granular cells. It is located along with the retrosplenial area and the precuneus.

Histologically, it comprises less than 6 layers of
neurons. It is regarded to have structure in between 6-layered neocortex and
allocortex.

Connections

Here, we will discuss about the afferent and the
efferent connections of the anterior and posterior cingulate cortex.

Afferent Fibers

The afferent fibers of the two areas are different from
one another.

The anterior cingulate cortex receives afferent fibers from the ventral lateral and ventral anterior nuclei of thalamus. It also receives fibers from the hippocampal formation. The afferent from the midline and interlaminar nuclei of thalamus also reach the anterior cingulate cortex.

The anterior mamillary nuclei of the anterior cingulate cortex receive fibers from the subiculum. The anterior nucleus receives the fibers from the mamillo-thalamic tract.

The posterior part of the cingulate cortex receives
most of afferent fibers from the superficial nucleus of thalamus. It also
receives fibers from the subiculum of the hippocampus.

Efferent Fibers

The rostral part of anterior cingulate cortex sends efferent fibers to superior temporal gyrus and prefrontal cortex. The ventral part sends fibers to the insular cortex, premotor cortex, orbitofrontal cortex, amygdala, and inferior parietal lobe. It also sends projections to the perirhinal cortex.

The efferent fibers of the posterior cingulate cortex
have different destination. This part of cingulate cortex sends projections to the
dorsolateral prefrontal cortex, anterior prefrontal cortex, orbitofrontal
cortex, parahippocampal gyrus, and inferior parietal lobe.

Blood Supply

The blood supply of cingulate cortex is derived from
the anterior cerebral artery. The pericallosal branch gives off cortical
branches. These cortical branches provide blood to most of the cingulate
cortex.

Physiology

In this section, we will briefly discuss the functions of the cingulate cortex.

Error Detection

This function is performed by the anterior cingulate cortex. It has been proved that the anterior cingulate cortex is involved in the process of error detection and is also active during the process of correct response.

It also plays an important role in conflict monitoring. It not only monitors the conflict but provides important cues to other areas of the brain in order to cope with the conflict.

Social Evaluation

The anterior cingulate cortex is also involved in the process of social evaluation. It is responsible for the detection and assessment of social processes which also include social exclusive behavior. It is responsible for enhanced arousal which is associated with repetitive social evaluation.

Consciousness

The anterior cingulate cortex is responsible for the increased level of consciousness. It has been shown that this area is greatly active in people who were emotionally more aware than the other people. Thus, the anterior cingulate cortex is directly associated with the degree of awareness.

Registration of Pain

The anterior cingulate cortex is associated with the registration of pain. The intensity of signals in this part of the cingulate cortex is associated with the intensity of pain. This part of the cortex is linked to the experience of pain and is responsible for the emotional reaction to the pain rather than the perception of pain.

Memory and Learning

Being a part of the limbic system, it is also responsible for the process of memory and learning. This function is mainly performed by the posterior part of the cingulate cortex. It is responsible for spatial memory and spatial learning. It has been shown that the neuronal activity is greatly enhanced in this area when a person recalls autobiographical memories.

This part of the cortex is also important for
emotional salience. It is strongly activated by an emotional stimulus,
irrespective of the positive or negative nature of the stimulus. This
characteristic feature is not shown by other parts of the limbic system such as
the amygdala.

Meditation

The posterior cingulate cortex is also responsible for meditation and sleep. It has been shown that this part of the cortex is activated during the process of self-related thinking. On the other hand, it is deactivated during the process of meditation. The posterior cingulate cortex is deactivated during effortless and undistracted wandering of mind.

Clinical Significance

The following are the important medical conditions associated with cingulate cortex.

Alzheimer’s Disease

It is associated with the posterior part of the cingulate
cortex. This part is commonly affected by neurodegenerative diseases. The
reduced metabolism in the posterior cingulate cortex is considered to be the
earliest sign of disease. This sign is frequently present before the clinical
diagnosis of Alzheimer’s disease is made.

Autism Spectrum Disorders (ASD)

These disorders are also associated with the metabolic defects in the posterior cingulate cortex. Patients with ASD show abnormal functional responses and reduction in functional connectivity of the posterior cingulate cortex.

Attention Deficit Hyperkinetic Disorder (ADHD)

It has been shown that patients with ADHD show developmental abnormalities in the posterior cingulate cortex. Although the function of cingulate cortex is intact in ADHD, patients show an increase in the left posterior cingulate cortex.

Depression

It is the most common psychiatric problem of this era. It has been linked with abnormal functional connectivity in the posterior cingulate cortex. The functional connectivity in depression may be increased or decreased. It has been shown that patients who undergo deep brain stimulation of the cingulate cortex show improvement in the symptoms of depression.

Schizophrenia

Schizophrenia is a psychiatric disorder characterized by hallucinations, delusions, tremors, disorganized thinking, and lack of emotional intelligence. It has also been linked to the abnormal activity of neurons in the cingulate cortex, specifically in its posterior part.

Conclusion/Summary

Cingulate cortex is the part of cortex associated with learning, emotions, and memory. It is present on the medial side of cerebral hemispheres, just above the corpus callosum. It is a part of the limbic system and limbic lobe.

It is divided into two parts, the anterior part and
the posterior part.

Both these parts have different connections and
relations which have been discussed in the subsequent headings.

The blood supply of the cingulate cortex is obtained
from the branches of the anterior meningeal artery.

Many important functions are performed by the cingulate cortex. These include;

• Error detection
• Social evaluation
• Consciousness
• Registration and emotional
  association of pain
• Learning and memory

A number of psychiatric conditions are associated with the metabolic and functional abnormalities in the cingulate cortex. These include;

• Depression
• ADHD
• Alzheimer’s disease
• Autism Spectrum Disorder
• Schizophrenia

The detail of all these pathologic conditions have been discussed in the section of clinical significance.

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