Although we usually talk about the sensory channels that help us understand our environment by referring to the “five senses,” the truth is that, in reality, there are more.
Touch, for example, is related to our ability to perceive pain and changes in temperature. But there is still another “sense” that we tend to overlook, and whose importance becomes evident in cases where a neurological disorder causes it to disappear. This biological alteration is known as autotopagnosia, and the ability it suppresses is the capacity to know at any given moment which parts of space are being occupied by parts of the body.
What is autotopagnosia?
Etymologically, the term autotopagnosia already gives clues about its meaning: it is a type of agnosia, like prosopagnosia or visual agnosia, in which the impairment is related to the ability to know the positions of the parts of one’s own body or those of another person or entity.
Thus, this neurological disorder, which is sometimes also called somatotopagnosia, is expressed through serious difficulties in knowing the orientation and placement of body parts, resulting from an organic lesion in certain areas of the brain.
Causes of autotopagnosia
Autotopagnosia usually appears in association with lesions in the parietal lobe of the left cerebral hemisphere. However, its specific causes are not easy to determine in detail.
As with almost all neurological disorders, it is very difficult to identify a single isolated cause that explains the appearance of symptoms, because the nervous system (especially the human nervous system) is extremely complex, both in its structure and in its functioning.
Additionally, cases in which autotopagnosia appears are rare, which makes it difficult to study. However, possible explanations have been proposed regarding how this condition arises.
There are three main hypotheses about the possible causes of this disorder. The first views autotopagnosia as a result of a lesion in areas of the posterior left hemisphere related to language (it could simply be a type of anomia, which is the inability to refer to elements by their designated name); the second interprets this impairment as a disruption in certain parts of the parietal lobe involved in imagining a three-dimensional model of the body; and the third characterizes it as a visuospatial problem also related to the parietal lobe.
The possibility of thoroughly analyzing the causes of autotopagnosia is hindered by the fact that it often appears alongside other neurological disorders, such as apraxia.
Symptoms of this neurological disorder
People with autotopagnosia have serious difficulties in locating body parts, whether their own, someone else’s, or those of a drawn figure. In addition, they typically show two types of symptoms:
Semantic errors
These types of symptoms correspond to cases in which, when asked to point to a part of the body, the person points to another that belongs to a similar semantic category. For example, instead of pointing to an arm, they point to a leg, or instead of pointing to a knee, they point to an elbow.
Contiguity errors
This symptom is related to the person’s inability to know exactly where a body part is located. For example, when asked to point to the chest, they point to the abdomen, or when asked to point to the ear, they point toward the neck.
It is also important to note that not all cases of autotopagnosia are the same. While some people are unable to identify the location of body parts on themselves or another entity, others may only have difficulty locating their own, or they may be able to recognize the body part when they touch it, for example.
Treatment of somatotopagnosia
Since it is a neurological disorder caused by lesions, it is believed that the symptoms cannot completely disappear and that the marks left in the brain by the injury are irreversible. However, it is possible to work on mitigating the symptoms of the condition by teaching the person to adopt habits that make daily life easier.
Unfortunately, to this day there are no known pharmacological treatments that have proven effective in these cases, which is why it is necessary to approach each case in a highly personalized manner to understand all the challenges patients face and the possible opportunities they may have to make progress in their way of functioning.
Conclusion
Autotopagnosia is a neurological disorder that is difficult to understand because its nature is still unclear. It could be a language-related failure (meaning difficulty in naming things) or visuospatial (meaning difficulty in knowing where a body part is located, even when its name is known).
More research is needed to develop more effective intervention programs.
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