New insights into the role of tactile mechanoreceptors in the hand during object rotation are provided by Birznieks and colleagues (2010), in this issue of The Journal of Physiology, in an elegant study of the spike trains evoked by torsional and contact loads applied to the fingertips. The fine manipulative capacity provided by our fingers is possible because of their high sensory innervation density; if we lose tactile sensation in our fingers we lose manual dexterity. When we grasp an object in the hand and manipulate it, both predictive and sensory-guided mechanisms are engaged. Predictive feed-forward processes concerning the preferred grasp points and the initial applied grip force are normally employed at the outset of grasp (reviewed in lohansson, 1996; Wolpert & Miall, 1996; Flanagan & Wing, 1997). Somatosensory feedback from tactile receptors in the hand serves to confirm or refute these predictions, and to update learned grasp and manipulatory behaviours.
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