The occipital lobe is the part of the human brain responsible for interpreting information from the eyes and turning it into the world as a person sees it.
The occipital lobe has four different sections, each of which is responsible for different visual functions.
Disorder in the occipital lobe may cause disorder in the vision or the brain itself. There may also be a link between the occipital lobe and conditions such as epilepsy.
Read on to learn more about the occipital lobe, including its specific functions.
The occipital lobe is one of the four major brain lobe pairs in the human brain. The occipital lobe is so named because it rests below the occipital bone of the skull. It is also the smallest of the lobes.
There are actually two occipital lobes — one on each hemisphere of the brain. The central cerebral fissure divides and separates the lobes.
The occipital lobes are located on the rear part of the upper brain. They sit behind the temporal and parietal lobes and above the cerebellum, separated from the cerebellum by a membrane called the tentorium cerebelli.
The surface of the occipital lobe is a series of folds, including ridges called gyri and depressions called sulci. Because there is no ordered structure to the occipital lobe, scientists use these sulci and gyri to identify the area of the lobe.
Apart from these, there are no structural distinctions in the lobes. Scientists separate the lobes further based on basic function.
The occipital lobe itself contains different sections, or areas, and each of these has a different set of functions. These include:
- the lateral geniculate bodies
- the lingula
- the primary visual cortex, known as Brodmann area 17 or V1
- the secondary visual cortex, known as Brodmann areas 18 and 19 or V2, V3, V4, V5, which surrounds the primary visual cortex
- the dorsomedial stream
In general, the occipital lobe deals with aspects of vision, including:
- depth perception
- color determination
- object recognition
- face recognition
- memory information
Humans also have binocular perception due to the fact that the occipital lobes on either hemisphere also receive visual information from both of the retinas.
Because this combines two images into one image in the brain, it helps give more depth and provide spatial awareness of the environment.
That said, the visual world is highly complex. Because of this, the process of decoding this information is also very complex.
The sections below will discuss the different sections of the occipital lobe in more detail.
Primary visual cortex
The primary visual cortex, called Brodmann area 17 or V1, receives information from the retina. It then interprets and transmits information related to space, location, motion, and color of objects in the visual field.
It does this through two different pathways called streams: the ventral and dorsal streams.
Secondary visual cortex
The secondary visual cortex — called Brodmann area 18 and 19 or V2, V3, V4, V5 — receives information from the primary visual cortex. The secondary visual cortex deals with much of the same type of visual information.
The ventral stream is one pathway the primary visual cortex uses to send information. It takes information to the temporal lobe, which interprets the information and helps the brain give meaning to objects in the field of vision.
This helps with object recognition and gives conscious awareness to what a person is seeing.
The dorsal stream is the other pathway the primary visual cortex uses to send information. It shares information about an object’s location and carries it to the parietal lobe, which takes in other information about the space and shape of objects in the field of vision.
Lateral geniculate bodies
The lateral geniculate bodies take part of the raw information from the outer part of the retina to the visual cortex.
The lingula gathers general information about the field of vision from the inside half of the retina.
The combination of information from the lateral geniculate bodies and the lingula helps create spatial awareness and gives depth to the visual information.
Other contributing sections
Although modern science has revealed much about how the occipital lobe reveals the visual world, researchers are still learning new information about the occipital lobe and exactly how it functions.
No section of the brain is truly independent, and this includes the occipital lobe. For example, the occipital lobe takes information from the retina in the eye and translates it into the visual world. As such, it relies heavily on the eyes themselves.
The eyes themselves also have muscles that need controlling. The motor cortex in the brain is responsible for these movements, therefore also playing a role in vision.
The temporal and occipital lobes share important interactions, as well. The temporal lobe gives meaning to the interpreted visual information from the occipital lobe. It also stores the information, to a degree, in the form of memories.
In some cases, it may also be possible for other sections of the brain to compensate for any damage affecting the occipital lobe.
Dysfunction in the occipital lobe may lead to one or more dysfunctions in the brain, vision, or everyday functioning. It may cause or contribute to any of the following conditions.
Because the occipital lobe deals with vision, one possible result of damage in this area is full or partial blindness. Loss of sight is not always straightforward, however, and the person may instead lose one or more specific functions of their vision.
Anton syndrome is a rare form of blindness that occurs without the person being aware of it. They may deny their vision loss, even if a healthcare professional presents evidence showing that they have vision loss.
Riddoch syndrome is a rare condition in which a person is only able to see moving objects. Stationary objects simply do not appear in their field of vision. The person can also not perceive shape or color.
Epilepsy shares a link with the occipital lobe in some cases. If a person is more prone to occipital-type seizures or photosensitivity seizures, flashes of light or images that contain multiple colors may trigger these seizures.
Other forms of dysfunction
The type of dysfunction to affect the body can vary based on where the dysfunction or injury occurs in the occipital lobe. Some possible examples include:
- difficulty recognizing everyday objects
- trouble understanding basic colors, shapes, or sizes
- difficulty recognizing familiar faces
- difficulty balancing, moving, or standing
- visual hallucinations, such as flashes of light
- changes in depth perception
- difficulty detecting moving objects
- difficulty reading or writing, due to trouble recognizing words
The occipital lobe is one of the four major lobes in the mammalian brain. The occipital lobe is mainly responsible for interpreting the visual world around the body, such as the shape, color, and location of an object.
It then relays this information to other parts of the brain, which give this visual information its meaning.
Dysfunction in the occipital lobe may cause a number of bodily dysfunctions, such as irregular vision, difficulty standing, and blindness. Some conditions, such as epilepsy, may also have a link to dysfunction in the occipital lobe.