Body schema is the awareness of one’s own body, including its body-surface demarcation from the environment. The concept is present from birth and thus presumably genetic, but does not fully form until after puberty. In addition to perceptual stimuli, language development contributes to its formation.
What is the body schema?
The body schema is the awareness of one’s own body, including its body-surface demarcation from the environment. Body schema is a neuropsychological concept that describes the mental representation of one’s body and orientation to it. The concept consists of two components: imagination and perception of the body. These two components, although distinct from each other, are highly correlated in a healthy person. Awareness of the body and its limitations has existed since birth. It is permanently reaffirmed by the multisensory information of the senses of skin, movement, and balance, and is fully formed only through the repeated interaction of the individual with the environment. The body schema is the basis for the development of subjective individuality and self-worth. It is an important reference for all actions and reactions, although it is a rather unconscious quantity. Arnold Pick first described the basic features in 1908. Pierre Bonnier described a disturbance of the concept already three years earlier under the term ‘Aschématie’. The body schema is based on sensory and sensory stimuli of proprioception. However, the conceptual character of the body schema is relatively independent of sensory and sensory stimuli and thus not characterized by sharp object consciousness. Thus, the body schema belongs to the imaginations rather than to the perceptions. In addition to proprioception, social information, such as naming of body parts, contributes to its formation.
Function and task
The body schema is used by humans to orient themselves in space. Furthermore, because the body schema delineates one’s body from the environment, it is the anchor point of subjective individuality and the starting point for self-esteem. The interaction between external perception and one’s own body world is a field of tension of the human being, which is described by the opposites of exteroception and interoception. Already with birth a body schema is present. This preverbal recognition process occurs through actions in both hemispheres of the brain and would thus be disturbed by lesions of both hemispheres. The preverbal body schema continues to develop with language development. In communication, the language dominant hemisphere also becomes dominant for the body schema. The language dominant hemisphere recognizes and communicates symbols on its own. From then on, it develops the body schema, which remains as a fixed entity, for example, even after the loss of an extremity. The cerebral, i.e. by the brain accomplished, integration achievement is assumed as basic condition for an intact body schema. It is also called autotopic homunculus and is multiply bound to the highest cerebral cortical areas. Sensory-motor stimuli from the peripheral nervous system are projected and processed into the primary sensitive cortical fields. They therefore correspond to a miniaturized model of peripheral body regions. However, integration and coordination do not take place exclusively in the primary cortices, but in three different stages. In addition to the primary fields, tertiary association fields of the dominant cerebral hemisphere are involved in the process. In contrast to integration, there is probably no articulated somatotopic substrate for the body schema. Rather, the body schema seems to be based on a purely functional interplay of different non-topically structured brain fields. For this reason, the body schema is already disturbed in fatigue, for example. However, because of the connections to the somatotopically segmentally structured cortical field gyrus postcentralis, at least a partial somatotopic structure is attributed to the body schema. A genetic basis for the schema is suspected.
Diseases and disorders
The body schema may be distorted by mental disorders involving disorders of consciousness. It also plays a sometimes difficult role after amputations. If an amputated limb is not replaced expeditiously with prostheses, patients often retain the old body schema. They continue to perceive the amputated body parts in this way and mentally move these phantom limbs along.When children are missing body limbs from birth, they still partially have the concept of the overall body schema. This observation has convinced scientists of a genetic basis of the body schema. The well-known phantom pains after amputations have only remotely to do with the body schema. They rather correspond to spontaneous excitations of the Noziz nerve cells, which were formerly assigned to the body part and form a so-called pain memory. The hyperexcitability of these nerve cells occurs as a result of surgical trauma. As after an amputation, the body schema is also disturbed in diseases in the dominant parietal region. The affected persons no longer pay attention to the left half of the body. There is then a so-called neglect. The patient does not perceive a paralysis of the left-sided extremities. This condition is also called anosognosia. In a similar way, there can be a neglect for blindness because of the body schema, as is the case in Anton’s syndrome. Neuropsychological disorders of this type also underlie ego disorders. An example of such an ego disorder is depersonalization. There are localized neuronal indications of a neurological representation of the psychological ego. However, so far the ego could not be assigned to a special brain center. Probably because it is too comprehensive and not yet properly understood by humans.