The parietal lobe of the brain is located between the frontal and occipital lobes and above the temporal lobes. The parietal lobes occupy locations in both the right and left hemispheres of the brain.
This lobe is especially important for integrating information from the body’s senses and enabling us to construct a coherent picture of the world around us.
The parietal lobes allow us to coordinate our movements in response to objects in our environment through the use of visual pathways, enabling us to process what and where things are.
Most important structures and areas of the parietal lobes
Below we will detail the most important areas into which the parietal lobe can be divided and what are the functions associated with each of these areas
Primary somatosensory area
The main function of the somatosensory cortex is to receive and process sensory information from all over the body, such as touch, temperature and pain.
Sensory information reaches this area of the brain via neural pathways in the spinal cord, brainstem and thalamus, which then project to the somatosensory cortex.
The sensory information is then integrated into a representation map of the body within the brain. One of the main responsibilities of the somatosensory cortex is the localization of sensations.
This means that it can pinpoint the exact point on the body where the sensation is perceived. It is also responsible for the perception of different degrees of pressure, for example, in order to judge the weight of objects.
This area of the parietal lobe can also perceive the shape and texture of objects through touch, as well as aiding spatial recognition.
Therefore, damage to the somatosensory area could lead to difficulties in perceiving touch, in recognizing objects by touch, and in recognizing one’s own body.
Inferior parietal lobe
The inferior parietal lobe is located at the lower end of the parietal lobes (inferior means ‘below’ or ‘lower’ in anatomical terms).
This region is primarily concerned with language, mathematical operations and body image. It is also important for spatial attention, visuomotor and auditory processing, and has been suggested to be involved in the perception of emotions through facial expressions.
Damage to this area may result in speech repetition deficits and the inability to complete mathematical problems.
Superior parietal lobe
Unlike the inferior parietal lobe, the superior parietal lobe is located at the top of the lobe (superior means “above” in anatomical terms).
This region is concerned with spatial orientation and sensorimotor integration. It also receives many visual and sensory signals from the hands.
Damage to this area can result in the inability to recognize objects by touch, as well as hemispatial neglect (a deficit of attention and awareness of one side of the field of vision).
Precuneus or precuneus
The precuneus is located on the medial surface of the parietal lobes. As such, it is one of the least mapped areas of the cortex.
Functional neuroimaging suggests that the precuneus is involved in tasks such as visuospatial imagery (being able to analyze, perceive and manipulate visual patterns and images), episodic memory retrieval (reliance on reactivation of sensory information that was present when a memory was encoded and processed) and the ability to adopt first-person perspectives.
This area is also believed to play a role in self-reflections and consciousness.
In one study it was found that having a sense of self-awareness, through the appraisal of one’s own personality traits as compared to those judged of others, was related to precuneus.
The angular gyrus is a small triangular area of the parietal lobe.
It helps the brain to associate symbols and meanings and assists in word recognition. This gives the brain the ability to assign meanings and name objects in the environment.
It also helps to use symbols and language, so it is involved in skills such as drawing, reading and reasoning. It helps a person understand written words and mathematical equations.
Damage to the angular gyrus, on the dominant side, can cause Gerstmann’s syndrome. Gerstmann’s syndrome is characterized by:
- An inability to write
- Inability to perform arithmetic operations
- Difficulty in recognizing which finger is which
- Difficulty in differentiating between the right and left side of the body
what other areas of the brain do the parietal lobes interact with?
It is a myth that a single region of the brain controls any one function. Rather, each region of the brain works in concert with the body. Without the environment, the brain could do little or nothing, and the parietal lobe is no exception
Its role in sensory processing means that the parietal lobe relies on a cascade of sensory inputs from all over the body, including the eyes, hands, tongue and skin. These disparate regions cannot function without input from the parietal lobe, which assigns meaning to the sensory information encountered each day.
The parietal lobe also sends signals to and receives signals from other regions of the brain, most notably the occipital lobe. The occipital lobe assists the parietal lobe in visual perception and processing, as well as in navigation and spatial reasoning.
Although each brain region has a specific set of functions, many of them are interchangeable and cross brain regions. Each brain region, for example, is vital for language processing. Some research has also found that when damage occurs in one brain region, nearby regions can compensate, especially if the injured person receives immediate and comprehensive occupational and physical therapy.
what are the functions of the parietal lobe?
The parietal lobe is vital for sensory perception and integration, including the management of taste, hearing, sight, touch and smell
It houses the primary sensory area of the brain, a region where the brain interprets information from other areas of the body. Research suggests that the more sensory information a region of the body provides, the more surface area of the parietal lobe is devoted to that area
For example, the fingers and hands are a prime location for sensory data, so much of the parietal lobe is devoted to receiving and processing their information.
Other functions of the parietal lobe include the following
- Distinguishing between two points, even without visual information.
- Localize touch: When an object is touched with any part of the body, the parietal lobe allows the sensation to be felt at the site of touch and not, for example, in the brain or the whole body.
- Integrating sensory information from most regions of the body.
- Navigation and visuospatial reasoning: When reading a map, following directions or avoiding tripping over an unexpected obstacle, the parietal lobe is involved. The parietal lobe is also vital for proprioception, i.e., the ability to determine where the body is in space, even in relation to itself. For example, touching one’s nose with one’s finger without the aid of a mirror is a function of the parietal lobe.
- Some visual functions, along with the occipital lobe.
- Assess numerical relationships, including the number of objects seen.
- Assess size, shape and orientation in space of both visible stimuli and objects that he remembers encountering.
- Mapping the visual world: several recent studies suggest that specific regions of the parietal lobe serve as maps of the visual world.
- Coordinating hand, arm and eye movements.
- Language processing.
- Coordinating attention.
Like the other regions of the brain, the parietal lobe is not fully understood. Researchers are constantly making new discoveries about the functioning of this brain region, and it is unlikely that we have identified all of its functions.
Disorders associated with injury and damage to the parietal lobe
Damage to the parietal lobes can result from conditions such as stroke, vascular disease, or tumor. It can also be the result of traumatic brain injury or infection.
There are many symptoms that can be associated with parietal lobe damage:
- Unsteady gait
- Inability to locate and recognize objects, events and body parts – hemispatial neglect.
- Inability to focus visual attention
- Difficulty discriminating sensory information.
- Lack of coordination
- Impaired ability to read and write, with no impairment in the ability to speak and comprehend speech.
- Impaired ability to draw.
- There are also functional differences in damage between the left and right sides of the parietal lobes. When the left side is damaged, it tends to cause more problems in making precise hand movements, resulting in clumsy drawings and difficulty in writing.
Damage to the left side can also cause problems with mathematics (acalculia), as well as cause more language disorders (aphasia). Gerstmann’s syndrome can also occur due to this damage.
A person with this condition may have difficulty identifying parts of his or her own body, be unable to distinguish the left and right sides of his or her body or surroundings, as well as difficulties with math, reading and writing.
Damage to the right side of the parietal lobes is primarily perceptual. People with this damage may be able to analyze an image in separate parts, but may have difficulty integrating them into a complete picture.
Damage to the right side may also affect a person’s ability with spatial skills, such as reading a map or completing a coherent drawing.
Finally, damage to the right side can affect self-care skills, such as washing and dressing, difficulty building things, and contralateral neglect (neglect on the opposite side of the damage, e.g., damage to the right side causes neglect on the left side).
We will detail below some of the syndromes associated with damage to the parietal lobes
Gerstmann’s syndrome occurs when there is lateral damage to the parietal lobe. The syndrome disrupts important functions of the parietal lobe and causes the person to have difficulty distinguishing left-to-right movement and location.
A person may have difficulty identifying his or her fingers and may be unable to distinguish the left and right sides of his or her body or surroundings.
People with Gerstmann syndrome may also have difficulty with equations, reading and writing because they cannot interpret symbols.
Gerstmann syndrome may occur due to reduced blood flow in the parietal lobe. It may develop after a stroke or due to another vascular disease in the brain that drastically reduces the blood supply.
The syndrome and similar symptoms may also occur with tumors in the parietal lobe or other forms of brain damage.
Balint syndrome is a rare disorder that occurs due to damage to both sides of the parietal lobe.
It encompasses many of the above symptoms and usually results in both visual and spatial difficulties, including symptoms such as optic ataxia, optic apraxia and simultanagnosia. Simultanagnosia is the inability to take in multiple elements of the visual environment.
Contralateral neglect usually occurs as a result of damage to the nondominant parietal lobe, which is usually the right lobe in people who are right-handed.
As a result, a person will have less awareness of his or her non-dominant side and the surrounding environment. A right-handed person with contralateral neglect would be less aware of the left side of his or her body, for example.
This can result in burns, bruises and other injuries.
There are severe and mild forms of this condition, and symptoms can vary widely.
Treatment of damage to the parietal lobes
Treatment of parietal lobe damage depends on the extent and location of the damage. Physical therapy, occupational therapy and speech therapy are typical treatments used for damaged parietal lobes.
These treatments can help the brain learn to work around the damage. Therapists will help create situations for the individual to learn how to function in the world and remind patients to look at their body when making movements.
Since patients often have trouble locating and recognizing their body, using their other senses, such as sight, can help them better navigate the world.