The parietal lobe is a region of the cerebral cortex with the function of integrating all sensory information. A review of their anatomy and physiology.
Each hemisphere of the human brain is composed of six different areas (four main and two additional). One of the most important, which we will talk about in this article, is the parietal lobe.
Below we will explore what are its most important functions in addition to theproblems that the individual may experience when this brain area is damaged.
- We recommend you read: “The 6 lobes of the human brain (anatomy, functions and images)”
What is the parietal lobe?
It is a brain region that, due to its size, represents 20% of the total cortex or surface of the brain, so we are talking about a relatively large area and therefore of considerable relevance for the functioning of the nervous system.
As for its structure, we could make a division that would lead to four different areas:
- Superior parietal lobe.
- Inferior parietal lobe.
- Posterior parietal cortex.
- Postcentral gyrus.
We will delve into the attributions of each of them later.
Where is it located?
The cerebral hemispheres, left and right, are symmetrical from the corpus callosum, the area that divides them transversely. What does this mean? That inboth hemispheres we will find the same lobes, each one located in mirror with respect to its counterpart.
Specifically, the parietal lobes would each be located under the corresponding parietal bone (left or right), in the upper lateral areas of the skull. As for their location in the brain itself, they would be between the frontal lobes (which are in front), occipital (which are behind) and temporal lobes (which are located below).
What are the main functions?
Within the wonderfully complex structure that is the human brain, the parietal lobe is responsible for carrying out the following tasks.
1. Somatosensation
This is where the brain receives andanalyzes the sensory information captured by the rest of the body, relating to temperature, pressure and other characteristics of touch, our own position in space (what is known as proprioception), balance and also nociception, or the reception of pain. These data allow us to act accordingly and thus be able to anticipate potential hazards that we find in the environment.
All this information is sent by the thermal, mechanical and chemical receptors that we have distributed both in the skin and in organs, muscles and even bones. The specific area responsible for the somatosensation would be the postcentral gyrus. Therefore, this is where we would place the primary somatosensory cortex.
2. Sensorimotor integration
Another of the great responsibilities of the parietal lobe is to coordinate all the information that comes from the different areas of the body, both those seen in the previous point and those related to sight and hearing, toprovide us with a global sensation of what we are experiencing at each momentand move accordingly. We would be talking here, mainly, about the superior parietal cortex
For all these qualities we can sometimes also find the term association cortex to refer to the parietal lobe in brain maps that divide the different areas by their type of activity.
3. Spatial information
Thanks to this brain area we are also able to discern to estimate the spatial characteristics of the different objects that are around us: their figure, their position with respect to us and their dimensions. This task is performed mainly in the upper region of these lobes, an area that also has a great responsibility in fine motor skills.
4. Other cognitive functions
But that’s not all. The parietal lobe is also responsible for other no less important missions, such asattentional processes, understanding written language and number processingby which we can solve mathematical questions.
All of them are processes involved in the part of short-term memory known as working memory, a theoretical concept coined by Alan Baddeley and frequently used in cognitive psychology to refer to the active processing of data that occurs in the memory mechanisms of human beings, as opposed to the mere storage of memories.
The lower region of the parietal lobe, in addition, also has great importance inthe identification of emotions in the facial expression of our peers, something fundamental for our daily social interactions.
Are there differences between hemispheres?
Our brain is a structure that works in a contralateral way with respect to the rest of the human body. This means that the left hemisphere receives data from theright body part and controls that area, while the left hemisphere receives and controls data from the right. Therefore, it is usual for right-handed people to show more intense activity in their left parietal lobe and, on the contrary, left-handed people, do the same in the right parietal lobe.
As there is a large majority of right-handed people over left-handed people (87%-92% right-handed versus 8%-13% left-handed) it is usual to refer to the left parietal lobe (and the entire hemisphere, in general) as dominant, as opposed to the right, which would be the non-dominant.
As for the specific tasks of each of them, it should be noted that the left has a greater relevance in the processing of alphanumeric symbols, whilethe right seems to be more responsible for visual interpretations. So don’t forget to thank this piece of brain the next time you manage to get on a map and measure distances properly!
It is important to be clear that, although there are these lateral tendencies for certain tasks, all people use both lobes together, and although there is a certain dominance in any of them, depending on the task, the execution of it is only possible due to the simultaneous work they do.
Possible lesions in the parietal lobe
Once the main functions of these brain regions have been studied, we will be able to better understand the possible disorders that a person can suffer if one or both lobes are physically altered.
1. Lesion in the left parietal lobe
Someone with this type of trauma may havetrouble receiving and processing sensations properlyfrom their right side of the body. In addition, for the most common tasks of this lobe, the person could experience any of the following dysfunctions:
- Agraphia: trouble expressing oneself verbally in writing.
- Aphasia: language alterations.
- Acalculia: difficulties in performing mathematical tasks.
- Agnosia: loss of the ability to process sensory information.
- Confusionbetween the perception of the right and the left.
The neurological disease known as angular syndrome or Gerstmann syndrome would encompass some of these symptoms, among others.
2. Damage to the right parietal lobe
If, on the other hand, the damage has occurred in the right lobe, we could find itdifficult to process the information coming from our left side. Some of the alterations that we could experience in this case would be the following:
- Problems when making drawings.
- Anosognosia: it is about the non-perception of one’s own pathology (beware, it is not a simple denial).
- Hemineglect: failures in self-care, in this case of the left side of the body.
- Constructive apraxia: damage to the ability to construct figures.
- Changes in the individual’s personality.
3. Problems in both lobes
If it were the case that a patient suffers damage to both parietal lobes, he could suffer from Bálint syndrome, a neurological disorder that is mainly characterized by three symptoms related to the sense of vision:
- Oculomotor apraxia: not being able to move the eyes voluntarily.
- Optic ataxia: coordination problems between vision and our movements.
- Simultagnosia: impossibility of relating the images of a set.
4. Combined damage to other lobes
If the person has suffered damage to wider areas of the brain involving not only the parietal lobes, but also the temporal lobes, they may experience more severe problems than their personality and/or memory abilities in a significant way.
To finish
After delving into the different characteristics of the parietal lobe, we can already get a general idea of what its main responsibilities are.
To summarize, we can conclude that theparietal lobes are responsible for our brain being able to unify the huge amount of information that comesto it at all times and integrate it to make sense of it and allow the rest of the areas to act in one direction or another.
A multitude of actions that we perform on a regular basis every day, at every moment, would be unfeasible without this “brain coordinator” who is responsible for analyzing the valuable information received.
But we must not forget that, both bilaterally and structurally, the brain functions as a single block, so all these tasks would not be possible without coordination with the rest of brain structures and other parts of the nervous system.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.