The parietal lobe, located in the upper middle part of the cerebral cortex, plays a central role in integrating sensory information from various body parts, understanding spatial orientation, and processing information about touch.
In psychology, it’s crucial for tasks such as attention, spatial reasoning, and distinguishing between self and others, thereby influencing perception and interpersonal interactions.
Where is the parietal lobe located?
The brain’s parietal lobe is situated between the frontal and occipital lobes and above the temporal lobes. The parietal lobes take up premises in the brain’s right and left hemispheres.
This lobe is particularly important in integrating information from the body’s senses to allow us to build a coherent picture of the world around us.
The parietal lobes allow us to coordinate our movements in response to the objects in our environment through visual pathways – allowing us to process what and where things are.
What Does the Parietal Lobe Do?
The parietal lobe is pivotal for integrating sensory data from different modalities. In psychology, it’s associated with spatial awareness, attention allocation, and tactile information processing.
Its role extends to understanding objects’ properties, arithmetic calculations, and differentiating between self and others, influencing our environment’s perception and navigation.
Below is a list of some of the associated functions of the parietal lobes:
- Perception of the body
- Perception and integration of somatosensory information (e.g. touch, pain, pressure and temperature).
- Spatial mapping and attention
- Visuospatial processing
- Coordination of movement
- Reading
- Writing
- Number representation (mathematics)
The parietal lobes can be divided into two functional areas. The first is sensation and perception, which integrates sensory information to develop a single perception (also known as cognition).
The second is integrating sensory input, which is mainly visual and aids in constructing spatial maps to represent the world around us.
The parietal lobes contain several spatial reference maps of the body, which are distinct and constantly updating as we continue to interact with the world.
The cortex of the parietal lobes (the outermost part) is known to be involved in processing attentional awareness of the environment, as well as being able to manipulate objects and give representation to numbers.
Neuropsychologists believe that the left and right sides of the parietal lobes play different roles. The left side is believed to be important in keeping track of the location of parts of the body which are moving.
The right side, however, is believed to be important in helping us keep track of the space around us.
Substructures of the Parietal Lobe
The parietal lobe is structurally divided into the somatosensory cortex, inferior parietal lobe, superior parietal lobe, and precuneus.
Somatosensory Cortex
The somatosensory cortex’s main overall function is to receive and process sensory information from the entire body, such as touch, temperature, and pain.
The sensory information is carried to this brain area via neural pathways to the spinal cord, brainstem, and thalamus, which then project to the somatosensory cortex.
The sensory information then gets integrated into a representational map of the body within the brain.
One of the main responsibilities of the somatosensory cortex is the localization of sensations.
This means it can pinpoint the exact point where sensation is felt on the body. It is also responsible for the perception of different degrees of pressure, for example, being able 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 with spatial recognition.
Therefore, damage to the somatosensory cortex could result in difficulties perceiving touch, recognizing objects by touch, and recognizing one’s own body.
Inferior Parietal Lobe
The inferior parietal lobe is located at the lower end of the parietal lobes (inferior meaning ‘below’ or ‘lower’ in anatomical terms).
This region is concerned primarily 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 perceptions of emotions through facial expressions (Radua et al., 2010).
Damage to this area may result in impairments in speech repetition and being unable to complete mathematical problems.
Superior Parietal Lobe
In contrast to the inferior parietal lobe, the superior parietal lobe is situated at the top of the lobe (superior meaning ‘above’ in anatomical terms).
This region is concerned with spatial orientation and sensorimotor integration. It also receives a lot of visual and sensory signals from the hands.
Damage to this area may result in the inability to recognize objects by touch, as well as hemispatial neglect (a deficit in attention and awareness of one side of the field of vision).
Precuneus
The precuneus is located on the medial (middle) surface of the parietal lobes. Because of this, it makes it one of the least accurately mapped areas of the cortex.
Functioning 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 the reactivation of sensory information that was present when encoding and processing a memory), and the ability to take first-person perspectives.
This area is also thought to play a role in reflections of the self and consciousness.
It was found in a study that having a sense of self-awareness, through rating one’s personality traits, compared to those judged by others, was related to the precuneus (Lou et al., 2004).
What Happens When the Parietal Lobe is Damaged?
Damage to the parietal lobes may be the result of conditions such as a stroke, vascular disease, or a tumor. It could also have resulted from a traumatic brain injury or an infection.
There are many symptoms that can be associated with damage of the parietal lobes:
- Walking unsteadily
- Inability to locate and recognize objects, events, and parts of the body – hemispatial neglect.
- Inability to focus visual attention
- Difficulty discriminating between sensory information.
- Disorientation
- Lack of coordination
- Disrupted ability to read and write without causing impairments in the ability to talk and understand speech.
- Impaired ability to draw.
There are also functional differences of damage between the left and the right side of the parietal lobes. When the left side is damaged, this tends to cause more issues with being able to make precise hand movements, resulting in drawings being clumsy and writing difficulties.
Left-side damage can also cause issues with mathematics (acalculia), as well as leading to more language disorders (aphasia). A condition called Gerstmann’s Syndrome may also occur due to this damage.
Someone with this condition may have difficulty identifying parts of their own body, be unable to distinguish the left and right sides of their body or environment, as well as difficulty with mathematics, reading, and writing.
Damage to the right side of the parietal lobes is mostly perceptual. People with this damage may be able to analyze a picture in separate parts but may struggle to integrate these into a whole image.
Right-side damage can also affect a person’s ability with spatial skills, such as reading a map or completing a coherent drawing.
Finally, right-side damage can affect self-care skills such as washing and dressing, difficulty in constructing things, and contralateral neglect (neglect on the opposing side of the damage, e.g., damage to the right side causing neglect on the left side).
Treatment
Treatment for parietal lobe damage depends on the extent and location of the damage. Physical, occupational, and speech therapy are typical treatments that are utilized for damaged parietal lobes.
These treatments can assist your brain in learning to work around the damage. Therapists will help to create situations for the individual to learn how to function in the world and remind patients to look at their bodies when completing movements.
As patients typically have issues with locating and recognizing their bodies, using their other senses, such as sight, can help them function better in the world.
Parietal Lobe Research Studies
- In terms of general parietal lobe function, it has been suggested that the posterior part (back) of the parietal cortex may be specialized for storing representations of motor actions (Milner, 1998).
- Menon et al., (2000) suggested that the parietal lobe may be involved in our ability to do mental arithmetic (mathematics). Damage to the parietal lobe has shown associations with deficits such as abnormal body image (Kandel, Schwartz & Jessel, 1991).
- Weiskrantz (1977) found that left parietal lobe damage was associated with problems with verbal memory and the ability to recall a string of digits.
- Garcia-Larrea & Mauguière (2018) found that damage to parts of the parietal lobes (posterior insula and medial operculum) can lead to a disassociated loss of pain and being able to recognize temperature.
- Fridriksson et al. (2010) used magnetic resonance imaging (MRI) and discovered that damage to the left inferior parietal lobes can cause impairments in speech repetition.
- Freund (2003) found that damage of the anterior (to the front) parietal lobe can produce somatosensory deficits, including weakened motor control.
- They also found that damage to the posterior (towards the back) parietal lobe can cause issues with virtually all aspects of somatosensory function.
- Fouquet et al., (2007) suggested that parietal lobe dysfunction, including the right temporo-parietal region, may be a precursor for the onset of Alzheimer’s Disease.
- Hale et al., (2007) used functional MRI (fMRI) to assess the brain functions of those with Attention Deficit Hyperactivity Disorder (ADHD).
- They found that parietal regions associated with completed executive functions failed to activate in those with ADHD. There is also evidence of right parietal dysfunction found in children who are diagnosed as having ADHD (Vance et al., 2007).
- Ferro et al., (2017) used MRI on individuals diagnosed with bipolar disorder. They found that there were significant reductions in white matter (containing nerve fibers that help transmit signals) and grey matter (important for processing information) in the parietal lobes of those with bipolar disorder.
- They suggested that parietal lobe white matter reduction could be an indicator of overall reduced functioning in those with bipolar disorder.
- Torrey (2007) suggested there may be a link between the inferior parietal lobe and schizophrenia. Functional dysfunction in the inferior parietal lobe is linked to sensory integration, body image, and the concept of self, which are also associated traits of schizophrenia. Finally, Zhou et al., (2007) studied parietal lobe volumes in those with schizophrenia.
- They found reductions in grey matter volumes in all parietal subregions and white matter volume reductions in the superior parietal gyrus (upper ridge).
- They concluded that volume reductions in the somatosensory cortices are common in those diagnosed with schizophrenia and can account for some of the associated symptoms.
References
Ferro, A., Bonivento, C., Delvecchio, G., Bellani, M., Perlini, C., Dusi, N., Marinelli, V., Ruggeri, M., Altamura, C., Crespo-Facorro. & Brambilla, P. (2017). Longitudinal investigation of the parietal lobe anatomy in bipolar disorder and its association with general functioning. Psychiatry Research: Neuroimaging, 267, 22-31.
Fouquet, M., Villain, N., Chételat, G., Eustache, F., & Desgranges, B. (2007). Cerebral imaging and physiopathology of Alzheimer’s disease. Psychologie & NeuroPsychiatrie du vieillissement, 5 (4), 269-79.
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Vance, A., Silk, T. J., Casey, M., Rinehart, N. J., Bradshaw, J. L., Bellgrove, M. A., & Cunnington, R. (2007). Right parietal dysfunction in children with attention deficit hyperactivity disorder, combined type: a functional MRI study. Molecular Psychiatry, 12 (9), 826-832.
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