Without the parietal lobe, humans would not be able to perform spatial reasoning, haptic perceptions, or the controlled execution of hand and eye movements. The cerebral area, which is particularly important for sensory perception, lies between the temporal, frontal, and occipital lobes and, as part of the central nervous system, can be involved in many, neurologic failures. Most commonly, tumors, strokes, or inflammatory CNS diseases, such as multiple sclerosis, are responsible for a functionally disabling lesion in the parietal lobe.
What is the parietal lobe?
The parietal lobe is the part of the cerebrum and central nervous system that is primarily responsible for sensory tasks. In medical terminology, this part of the brain is called the lobus parietalis, which is adjacent to the occipital lobe, as well as the frontal lobe, and thus forms approximately the middle part of the cerebrum. Because of its location in the upper part of the brain, the parietal lobe is sometimes called the parietal lobe. The parietal area is separated from the brain stem and cerebellum by the temporal lobe. Also located in the parietal lobule are eight of Brodmann’s areas, which describe the individual functions of the cerebral cortex.
Anatomy and structure
The parietal lobe is bounded anteriorly by the central furrow and posteriorly by the so-called ocipital lobe. The posterior border thus forms a line from the parietooccipital sulcus to the incisura praeoccipitalis. Below, the temporal lobe borders the parietal lobe. Thus, the inferior border of the area is approximately at the same level as the Sylvian fissure. In the parietal lobe lie the postcentral sulcus and, connected to it, the intraparietal sulcus, which divides the posterior cortex of the parietal lobe into two single lobules. Thus, the parietal lobe itself consists of the superior and inferior parietal lobules, also known as the posterior parietal cortex and inferior parietal lobule. This area of the brain contains many of the so-called Brodmann areas, which provides clues to its general function.
Function and tasks
Perceptions are the business of the parietal lobe. In general, this area of the brain performs important tasks in the processing of all sensory impressions. In particular, somasensory functions fall within the purview of the parietal lobe. These somasensory functions primarily involve the sensation of haptic, or tactile, perceptions. However, the parietal lobe is also involved in visual stimulus processing, especially the detection of movements in the immediate field of view of the observer. Thus, the parietal brain is largely responsible for spatial orientation. Spatial attention, spatial thinking, as well as reading and arithmetic would be inconceivable without this section of the cerebrum. Above all, the upper section of the parietal brain analyzes where things are located in the visual field of the observer or where they are moving to. In addition, the parietal lobe creates a plan of how the perceiver can get to these things. Even the purposeful execution of these movements takes place in the parietal brain. Movements and touches on the skin are also perceived via this part of the brain. Even the decision as to which stimulus in the field of view the observer pays attention to takes place in this area. Finally, the recognition of objects is implemented in the lower parietal brain. For this purpose, information from the visual field is related to sensory information. In the area of the gyrus angularis, the inferior parietal brain is also involved in speech and reading. As part of the parietal lobe, the intraparietal sulcus also has important tasks. This area connects the visual system with the human motor system and thus serves primarily for the controlled execution of hand movements and eye movements.
Diseases
Various, neurological disorders and diseases can occur in association with the parietal lobe, each of which shows up as lesions on imaging. One of the best known of these is Gerstmann syndrome, which was first described by Josef Gerstmann in the early 20th century and actually represents an entire symptom complex. In the meantime, this syndrome has become controversial, since most patients with the symptoms of the Gerstmann complex additionally show other symptoms. One of the individual symptoms of Gerstmann syndrome is agraphia. This means a difficulty in writing, which occurs independently of motor skills and intelligence.Symptomatically, there is also an acalculia, i.e. a difficulty with arithmetic. Due to the spatial functions of the parietal lobe, there are also left-right weaknesses as well as difficulties in counting and naming one’s own fingers and toes. Gerstmann syndrome occurs when there is damage to Brodmann area 40, which is located in the parietal lobe. Such damage can be due, for example, to a stroke or inflammation in this area due, for example, to a degenerative disease such as multiple sclerosis. In the case of both strokes and inflammation-related damage, the symptoms may resolve over the course of the next few days and weeks. A second disorder directly related to the parietal lobe is the rather rare Bálint syndrome. This involves an inability to make purposeful grasping or hand movements. In addition, purposeful movements of the eyes are disturbed, visual attention is impaired and complex images can no longer be fully grasped. Bilateral, parietal or parieto-occipital lesions in the brain are responsible for the clinical picture. In addition to brain tumors and diseases such as Creutzfeldt-Jakob disease, strokes and inflammatory diseases can also trigger these brain lesions. As was the case with Gerstmann syndrome, symptomatic deficits may regress in Balint syndrome if a stroke or MS lesion triggered them.
Typical and common brain disorders.
- Dementia
- Creutzfeldt-Jakob disease
- Memory gaps
- Brain hemorrhage
- Meningitis
