The role of self-touch in somatosensory and body representation disorders after stroke

Abstract

Somatosensory impairments occur in about half of the cases of stroke. These impairments range from primary deficits in tactile detection and the perception of features, to higher order impairments in haptic object recognition and bodily experience. In this paper, we review the influence of activeand self-touch on somatosensory impairments after stroke. Studies have shown that self-touch improves tactile detection in patients with primary tactile deficits. A small number of studies concerned with the effect of self-touch on bodily experience in healthy individuals have demonstrated that self-touch influences the structural representation of one's own body. In order to better understand the effect of self-touch on body representations, we present an informal study of a stroke patient with somatoparaphrenia and misoplegia. The role of self-touch on body ownership was investigated by asking the patient to stroke the impaired left hand and foreign hands. The patient reported ownership and a change in affect over all presented hands through self-touch. The time it took to accomplish ownership varied, based on the resemblance of the foreign hand to the patient's own hand. Our findings suggest that self-touch can modulate impairments in body ownership and affect, perhaps by helping to reinstate the representation of the body.

Now You Feel both: Galvanic Vestibular Stimulation Induces Lasting Improvements in the Rehabilitation of Chronic Tactile Extinction

“…This may reflect another interesting and testable hypothesis for future studies as somatosensory deficits and extinction are frequently encountered after brain damage (Van Stralen et al, 2011). Due to long-lasting effects of GVS, it may be used as an add-on-treatment in combination with other trainings of somatosensory deficits for rehabilitation.…”

“…Brain lesions, due to stroke, head trauma, or other causes impair a variety of somatosensory abilities dramatically in more than 50% of patients (Van Stralen et al, 2011). Among these impairments, tactile or somatosensory extinction is a frequent disorder (Kerkhoff et al, 2011).…”

Sensing the body in chronic pain: A review of psychophysical studies implicating altered body representation

“…Analgesia through self-touch may drive the anecdotal behaviour of clutching the painful hand with the other hand, thereby increasing a coherent cognitive body representation. The reinstatement of body representation through self-touch has also been demonstrated in a case report involving a stroke patient with somatoparaphrenia, the denial of ownership of a limb (van Stralen et al, 2011). Interestingly, patients with chronic pain report a weakened heat sensation by the cool finger during the thermal grill illusion compared with pain-free controls (Sumracki et al, 2014).…”

The Neural Basis of Self-Touch in a Pain-Free Situation

“…Coherent SII activity is thought to be actuated as a corresponding bodily state induced and maintained by temporally synchronous sensory/ motor signals from both hands, which are spatially symmetrical with respect to the body axis. Furthermore, this coherence is important for the maintenance of the body schema [59]. Moreover, coherent SII activity significantly modulated the left TPJ, which is involved in body ownership [60].…”