Author’s personal post-print version. The original article was published in: Journal of Motor Behavior, Vol. 46, No. 3, 2014, p.191-193. Copyright Taylor & Francis Group, LLC Link: http://www.tandfonline.com/doi/abs/10.1080/00222895.2014.880306?journalCode=vjmb20 The Bodywide Fascial Network as a Sensory Organ for Haptic Perception Robert Schleip 1 , Franz Mechsner2, Adjo Zorn 1 , Werner Klingler 1 1 Fascia Research Group, Division of Neurophysiology, Ulm University, Germany. 2 Department of Psychology, Northumbria University, Newcastle upon Tyne, England. T here can be no doubt that the article by Turvey and Fon- seca (2014) suggests an important reorientation in the field of motor control research. Up to now, most models in this field separate the passive tissue properties of the skeleton and other collagenous connective tissues from the active dy- namics of the muscular system, which itself is understood as being primarily controlled by the voluntary nervous system. According to this common perspective, neural coordination is seen as the key factor in and the main origin of our motor behavior: the neural system generates impulses to the motor units in the skeletal muscle fibers, and they in tum respond by pulling the origin and insertion of the muscles towards each other thereby exerting forces on the skeleton. In contrast to this widespread assumption, Turvey and Fon- seca (2014) place high importance on the fibrous collagenous connective tissues in the body; these are seen as providing a tensional network throughout the whole body, the biome- chanical properties of which provide the framework for mus- cular force transmission as well as for the haptic sensory system. Neural Signaling Dynamics: Merely a Downstream Effect of Altered Fascial Tissue Properties? Turvey and Fonseca (2014) extensively discuss the rare case of a male patient who suffered a loss of proprioception due to an isolated inflammatory neuropathy. Some members of our group had the opportunity to examine the myofascial tissue characteristics of this patient via manual palpation at rest as well as in sitting and standing. Two of our group's ex- perienced manual therapists examined the skin and underly- ing connective tissues of his shoulders, upper arms, and lower back and compared it with their therapeutic experience with healthy men of the same age group as well as with various connective tissue pathologies such as ankylosing spondylitis, Dupuytren's contracture, or Marfan's syndrome. The subjec- tive experience of both examiners was that tissue stiffness as well as tissue elasticity were well within the normal range for healthy individuals. Unfortunately no easy to use technology existed at that time to objectively assess the tissue properties. This finding, if valid and reliable, may suggest that the lack of proprioceptive perception in this unique person may be more than an adaptation of neural tissues in response to a change in fascial tissue properties. Modem sonographic elastography (Bercoff, Tanter, & Fink, 2004) or myometry (Aird, Samuel, & Stokes, 2012) could now be applied to more reliably examine whether the connective tissues of this man indeed show some very unusual properties that may serve as potential origin of the unusual and extreme defect in haptic perception in this person. However, if our impression gleaned via skillful touch was correct, then the causal correlation be- tween neural perception and connective tissue architecture may work- at least sometimes- in a two-directional man- ner. Alterations in neural dynamics may lead to modifications in motor behavior, which then influences connective tissue morphology. In addition, alterations in tissue architecture may lead to changes in neural processing which then induces modifications in motor behavior. It could be of interest to cl osely monitor the rapidly de- veloping exploration of distribution differences of different fascial mechanoreceptors in different topographical regions. Tesarz, Hoheisel, Wiedenhi:ifer, and Mense (2012) showed that in the human lumbar area, an increased density of pro- prioceptive as well as nociceptive nerves was found in more superficial fascial layers rather than in deeper layers of the lumbar fasciae. In addition Stecco et a!. (2007) reported a high density of proprioceptive nerve endings in retinacular fascial tissues (e.g., the retinaculae of the ankle and wrist region), whereas a lower density was found in fascial tis- sues specializing in muscular force transmission such as the lacertus fibrosus. Very recently a scarcity of free nerve endings has also been found in the superficial fascia of fibromyalgia patients, ex- cept for a particular increase in such nerve endings located on the arteriole-venule shunts within this layer (Albrecht eta!., 2013). If the hypothesis of Turvey and Fonseca is correct (i.e., that many perceptual alterations are primarily driven by changes in mechanical connective tissue properties), then it could be of interest to also look at these recent findings of altered distribution patterns in neural afferents and to exam- ine if and how they correlate with changes in fascial tissue properties. Recent Advances in the Field of Connective Tissue Related Terminologies Turvey and Fonseca (2014) emphasi ze the impact of a sys- tematic labeling of fascial structures. Based on the fact that fascia-related terminologies show the same degree of