A new stretch for muscle spindle research

Molecular neurobiology over the last few decades has provided detailed insight into many neural signalling mechanisms. However, an obvious gap in our knowledge is the nature of the mechanosensitive (MS) molecules and mechanisms operating within vertebrate specialized mechanosensors (e.g. touch, auditory and proprioceptors). This gap does not reflect any long-standing research neglect, since over the last 100 years some of the most renowned physiologists, including Ruffini, Sherrington, Adrian, Katz, Kuffler and Hunt, have at one time or another focused their research efforts on one of these mechanosensors – the muscle spindle or stretch receptor. As a consequence, the spindle became the first sense organ from which electrical activity was recorded, and the receptor where the sensory code was discovered (see Chapleau, 2007). In more recent years, behavioural studies have demonstrated that it is mainly sensory data from our ∼25 000 spindle receptors that the brain uses to construct an internal representation of our body's position and movement and thereby also our global sense of self (Proske & Gandevia, 2009).