The occipital gyri (OcG) are three

gyri In neuroanatomy, a gyrus (pl. gyri) is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci (depressions or furrows; sg. ''sulcus''). Gyri and sulci create the folded appearance of the brain in humans and other m ...

in parallel, along the lateral portion of the

occipital lobe The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the vi ...

, also referred to as a composite structure in the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

. The gyri are the superior occipital gyrus, the middle occipital gyrus, and the inferior occipital gyrus, and these are also known as the

occipital face area The occipital face area (OFA) is a region of the human cerebral cortex which is specialised for face perception. The OFA is located on the lateral surface of the occipital lobe adjacent to the inferior occipital gyrus. The OFA comprises a network o ...

. The superior and inferior occipital sulci separates the three occipital gyri. The intraoccipital sulcus, also known as the superior occipital sulcus, stems from the intraparietal sulcus and continues until the sulcus reaches the

transverse occipital sulcus The transverse occipital sulcus is a structure in the occipital lobe. The transverse occipital sulcus is continuous with the posterior end of the occipital ramus of the intraparietal sulcus The intraparietal sulcus (IPS) is located on the late ...

, separating the superior occipital gyrus from the middle occipital gyrus. The transverse occipital sulcus comes down along the lateral occipital surface or the inferior occipital sulcus.

Structural anatomy

The border between the

and the parietal and

temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in pro ...

s is characterized by different gyri: the superior occipital gyrus (also known as gyrus occipitalis superior), middle occipital gyrus (or gyrus occipitalis medius), inferior occipital gyrus (or gyrus occipitalis inferior), and descending occipital gyrus (gyrus occipitalis descendens).

Function

The occipital complex is primarily responsible for object recognition, including the functional properties and our perception of said objects. The middle occipital gyrus (MOG) was observed in a study of the early blind, which showed that it was activated more during spatial than nonspatial tactile and auditory tasks. Early blind people have an occipital cortex that is incorporates more senses than people with standard vision, but the MOG still keeps its functional role in processing space around a person. The

lingual gyrus The lingual gyrus, also known as the ''medial'' occipitotemporal gyrus, is a brain structure that is linked to processing vision, especially related to letters. It is thought to also play a role in analysis of logical conditions (i.e., logical ord ...

(also known as medial occipitotemporal gyrus) has been studied and found to be included in processing overall shapes, rather than the individual components that make up a shape. This shows that the lingual gyrus is active during visual processing. The inferior occipital gyrus has been found to be related to the visual function of processing faces. The IOG is connected to the amygdala via white matter connectivity. This allows the IOG to form a network for facial recognition with the amygdala.

Development

The occipital lobe becomes distinct at 18 weeks gestation, but the gyri are not clear until many weeks later. During development, the occipital lobe develops a lingual gyrus at 27 weeks of gestation. Secondary gyri develop by 30 weeks, and tertiary gyri develop during 40 to 42 weeks of gestation. The superior and inferior occipital gyri develop at the same time, usually shown somewhere between week 24 and 27 in brain development. Due to the unclear distinction in early neuroscience research as to whether there are two or three occipital gyri, there is not any data on when the middle occipital gyrus starts its formation, but it is likely at the same time.

References

{{Cerebral cortex Cerebrum Occipital lobe