Anatomical Location and Topography
The cingulate gyrus is located on the medial surface of the cerebral hemisphere. It belongs to the limbic lobe, which also includes the parahippocampal gyrus and the olfactory brain (rhinencephalon).
- On a sagittal section, key structures of the limbic system include the cingulate gyrus, the indusium griseum (supracallosal gyrus), and the fornix.
Cytoarchitecture (Brodmann Areas)
According to the cytoarchitectonic map of the cerebral cortex, the following areas are associated with the cingulate gyrus:
- Areas 23, 24, 32, and 33 — components of the cingulate cortex.
- Area 31 — also related to the region of the cingulate gyrus.
In Kleist's modification, areas 33, 24, 23, and 31 are associated with bodily self-awareness and self-perception.
Involvement in the Papez Circuit
The cingulate gyrus is a vital part of the Papez circuit — a closed neural loop involved in memory processing. The pathway of nerve impulses within this system is as follows:
- Hippocampus — the starting structure.
- Fornix.
- Mammillary bodies.
- Mammillothalamic tract (bundle of Vicq d'Azyr).
- Anterior nucleus of the thalamus.
- Thalamocingulate radiations — fibers projecting from the anterior thalamic nucleus to the cingulate gyrus.
- Cingulum (cingulate bundle) — conducts impulses from the cingulate gyrus back to the hippocampus, closing the loop.
From the cingulate gyrus, associative fibers also project to the neocortex.
Physiological Functions
- Emotions and Motivation: The cingulate gyrus is part of the "emotional limbic brain." Excitation within the cingulate gyrus and other limbic structures circulates through the circuit, maintaining motivational arousal.
- Autonomic Regulation: The cingulate gyrus participates in behavioral and autonomic regulation.
- Control of Micturition: Afferent fibers from the cingulate gyrus exert an inhibitory influence on the pontine micturition center. This center coordinates the simultaneous relaxation of both sphincters with contraction of the detrusor muscle via reticulospinal pathways.
Clinical Significance
In clinical practice, pathological changes in the cingulate gyrus are associated with limbic system disorders.
- Neurodegenerative Diseases: Parkinson's disease and multiple system atrophy belong to the synucleinopathies. Diffuse brain atrophy is described in these conditions. Degenerative processes in the limbic cortex, including the anterior cingulate gyrus, serve as the morphological substrate for dementia.