Tactile Stimulation Interventions: Influence of stimulation parameters on sensorimotor behavior and neurophysiological correlates in healthy and clinical samples

Abstract

The pure exposure to extensive tactile stimulation has been revealed to enhance sensorimotor functioning, without the requirement of attention or training. The induced effects, including increased tactile acuity and manual dexterity are assumed to rely on the induction of plasticity in the somatosensory cortex. They have repeatedly been observed in basic as well as clinical research. However, found results vary greatly in respect to the strength and direction of the induced effects on the behavioral and on the brain level. Multiple evidences show that differences in the stimulation protocols (e.g. one vs. multiple stimulation sessions) and parameters (e.g., duration, frequency, amplitude) might contribute to this variability of effects. Nevertheless, stimulation protocols have not yet been systematically compared. Identifying favorable parameters for tactile stimulation interventions is especially important because of its possible application as a convenient treatment option for patients suffering from sensory loss, maladaptive plasticity or certain forms of motor impairment. This review aims to compare the effects of different tactile stimulation protocols and to evaluate possible implications for tactile stimulation in research and application purposes. In order to do so, we reviewed the current research on tactile stimulation in the healthy population, with a focus on the effectiveness of the applied parameters regarding psychophysiological measures. Herewith we will discuss the association of stimulation-induced changes on the behavioral level with alterations in neural representations and response characteristics. Afterwards, we will specify practical applications of tactile stimulation in the healthy and clinical population and evaluate, whether the paradigms of our review apply to these contexts as well. The outlook is thereby to identify ways of optimizing stimulation protocols for research and application purposes, to induce a long lasting improvement of sensorimotor performance.