Anatomy of body representation: Preliminary results. Neurological substrates of finger agnosia, left-right disorientation and the distinction between body image and body schema of the hand revealed using lesion-symptom mapping.
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Introduction Body representation is a form of higher order somatosensory functioning containing multiple integrative processes in which information from different primary sensory modalities is integrated in a representation of the body. It is crucial for the conscious experience of the position and structure of our body parts and directing bodily movements. Disorders of body representation can affect the entire body or only specific body parts. The exact neurological substrate underlying body representation disorders remains unclear. The aim of the current study is to determine the neural substrate of body representation. Methodology In the present study we investigate in the neurological mechanisms underlying body representation-disorders in a sample of 17 first episode-stroke patients by linking neurological lesions with body representation disorders, i.e. finger agnosia, tactile localization impairments or left-right disorientation. Furthermore, the overlap and interplay between these impairments are mapped by using an advanced voxel-based lesion-symptom mapping approach. Results The voxel-based lesion-symptom mapping analysis showed that lesions significantly related to left right disorientation are mainly located in the right hemisphere, more specifically the caudate nucleus, external capsule and putamen. Analyses on finger agnosia and tactile localization impairments gained no significant results, but a qualitative lesion subtraction analysis shows a trend that lesions related to these disorders are also mainly situated in the right hemisphere, more specifically the caudate nucleus, external capsule , putamen and frontal cortex. Conclusions These results indicate that parts of the basal ganglia and the external capsule of the right hemisphere are key anatomical structures in body representation.