Somatosensory impact on motor cortex: how touch shapes motor behaviour

The ability to manipulate objects is a critical skill for humans. Such function is carried out primarily by the motor system. However, such a process would not be possible without the continuous information provided by the somatosensory system. The somatosensory feedback is particularly important when a movement must be adjusted while performing an action. Effective interactions between the somatosensory and motor systems are paramount for performing fine motor behaviour, as made dramatically clear by brain damage. Somatosensory deficits following nervous system lesions have received little attention compared to motor control. Yet, patients suffering from somatosensory deficits usually show reduced recovery of motor functions, preserved somatosensation being a good predictor of motor recovery. Despite the importance of touch in shaping motor behaviour, the functional relationships between the somatosensory and motor systems remain unclear. Here we examine the potential role of somatosensory information in modulating motor behaviour. We focus on a series of empirical studies that investigated the crosstalk between the somatosensory and motor systems, specifically on the role of touch in shaping motor behaviour. We will start by describing, across different species, the anatomical and neurophysiological connections between these systems and the nature of these communications. We will then present evidence from neuropathological studies and the severe consequences of somatosensory signals’ disruption on motor performance. Finally, we will examine the impact of short- and long-term tactile learning on the motor system as a promising approach for developing novel somatosensory-to-motor rehabilitation strategies, for people suffering from brain injury and other neurological conditions.