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Also called the cingulate gyrus, cingulate gyrus, or callosum-marginal gyrus, the cingulate gyrus is a fold located on the inner face of the cerebral hemispheres, which arcs around the corpus callosum . The cerebral hemispheres are the two halves into which the cerebral cortex is divided , that is, the layer that forms the surface of the brain; the corpus callosum is a thick band of nerve fibers connecting the two hemispheres.
The cingulate gyrus is part of the limbic system , a collection of structures like the amygdala, hypothalamus, and hippocampus, which lie beneath the cerebral cortex and surround the thalamus (a region located behind the brain and nestled below it). . This system is primarily responsible for affective life, emotions, basic impulses (fear, anger, tranquility, hunger, thirst, pleasure) and is a participant in memory formation.
Morphology
The cingulate gyrus is larger than the other structures that make up the limbic system. For this reason and for the functions it performs, which will be mentioned later, it has been called the “emotional brain.”
Regarding its location, it limits above with a deep groove in the cerebral cortex called the marginal fissure callosum, and below with the superior border of the corpus callosum. Because of this, it receives nerve fibers from the thalamus and from the most forward area of the cerebral cortex, called the prefrontal cortex; and projects its axons towards the temporal lobe (area of each cerebral hemisphere located at the level of the ears).
Some authors consider that the cingulate gyrus is divided into anterior cingulate cortex (ACC) and posterior cingulate cortex (PCC); others claim that, in addition to the previous two, there is a third division called the mediocingulate (CM) cortex.
anterior cingulate cortex (ACC)
It consists of the cortex of the gyrus located anterior to the front end of the corpus callosum. In addition to the thalamus and the prefrontal cortex, it receives information from the amygdala and from some areas that regulate autonomous functions (that do not depend on the will of the person) in the nervous system.
It is divided into pregenual anterior cingulate cortex (CCAp) and subgenual anterior cingulate cortex (CCAs).
- The pregenual anterior cingulate cortex (APC) lies in front of the corpus callosum. It is activated at times when decisions related to rewards are made and when self-generated emotions are triggered, storing memories associated with such emotions; it also participates in the recovery of memories about fear.
- Subgenual anterior cingulate cortex (ACCs) lies under the curvature of the corpus callosum. Control the expression of emotions.
Other functions of the anterior cortex are:
- Regulation of behavior.
- Evaluation of decisions in terms of goodness and justice.
- Analysis of conflicting or ambiguous situations.
- Optimization of decisions taking into account the evaluation of possible consequences.
- Control of attention and concentration.
- Establishment of short and long term memories.
mediocingulate cortex (CMC)
It is located in the middle third of the cingulate gyrus. It receives information from the amygdala and sends its projections to areas that control motor functions, that is, movements.
The CMC is involved in the orientation reflex, which consists of moving the head and eyes towards a stimulus while all attention is focused on it. It is also related to concentration and attention in carrying out a specific task.
Posterior cingulate cortex (PCC)
It consists of the cortex of the gyrus located posterior to the posterior end of the corpus callosum. It receives information from the thalamus, the frontal cortex and the hippocampus, which is why it is involved in the emotional component of memories, in the formation of permanent memories and in the spatial location of sounds in the environment.
Communication between the cingulate gyrus and other brain structures
The cingulate gyrus mediates the reciprocal connection between the hypothalamus and the cerebral cortex. Thus, the hippocampal formation (a set of structures adjacent to the hippocampus) processes information that comes from the cingulate gyrus and takes it to the hypothalamus; This, in turn, sends information to the cingulate gyrus and from there to the frontal cortex.
other functions
In addition to the functions already mentioned, the cingulate gyrus has other tasks at the level of the limbic system, such as:
- Processing and modulation of learning, motivation, attachment and maternal behavior.
- Grouping of involuntary response stimuli (alterations in blood pressure, heart rate and respiration) and voluntary (skeletal muscle movements).
- Triggering states of anxiety, aggression, fear.
- Mediation in the sensation of psychological and physical pain.
- Production of “emotional sounds”, that is, emotions that do not reflect the real state of mind. Therefore, it is associated with the feigned control of behavior.
- Maintenance of alertness and arousal.
- Increased visual perception and emotional activity.
dysfunctions
In general, it has been documented that patients with dysfunction in the cingulate gyrus manifest difficulty expressing their emotions, stuttering and mutism. When it occurs According to the severity of the injury, the problem-solving capacity is reduced, curiosity decreases, and a lack of concern for oneself, the family, or the future is manifested.
The most severe form of damage to the gyrus is called akinetic mutism. In this state, the patient is awake and can follow a visual stimulus with his eyes; occasionally, he may change his posture or utter a few words. However, he only eats if he is given food or evacuates if he is taken to the bathroom; furthermore, he does not respond to pain and is completely abstracted.
Associated diseases
Damage to the cingulate gyrus has been associated with autism, obsessive-compulsive disorder, and Alzheimer’s.
- Autism. Many manifestations resulting from damage to the cingulate gyrus correspond to autism spectrum disorders. Specifically, this structure is unusually thick or rough in patients with autism; There is also evidence of a greater number of nerve fibers (axons) in the white matter (deep tissue of the brain, in this case, the cingulate gyrus) and lower neuronal density in specific areas.
- OCD. In patients with lesions at the level of the mediocingulate cortex (CMC), it is not possible to inhibit the orientation response, so there is an excessive attentional focus on a specific task, which is associated with obsessive-compulsive disorder.
- Alzheimer’s. The posterior cingulate cortex (PCC) has been shown to be activated during memory retrieval by recalling significant memories to patients, such as family names. This activation does not occur in people with Alzheimer’s, so it has been proposed that CCP dysfunction may be related to this disease.
Sources
Acosta, M. Consent “from within” . New Age Magazine . 49:249-290, 2018.
Made, M. The Limbic System center of emotions . Neuroanatophysiology, nd
Pena, Bernardo. Cingulate gyrus: structure and functions . Psychoactive, November 11, 2021.
Valenzuela, E., Salas, W. Brain Internal Control Units: Hypothalamus, Limbic System, and Cerebral Cortex . (Teaching document No. 10). Bogotá: Editions Cooperative University of Colombia. doi: http://dx.doi.org/10.16925/greylit.1142, 2015.
