Highlights from the 2017 meeting of the Society for Neural Control of Movement (Dublin, Ireland)

摘要

Over 450 researchers, clinicians, and students attended the 27th annual meeting for the Society for the Neural Control of Movement held in Dublin, Ireland (May 1–5th, 2017). A satellite meeting focused on ‘The Roles of Proprioception and Vision in Perception and Action’, while during the main meeting topics ranged from learning sensorimotor maps from scratch to presynaptic inhibition for sensorimotor control to vestibular reflex pathways. Approaches ranged from behavioral assays to single neuron recordings to neural manifolds. Model systems ranged from fruit flies to mice to primates. There was a wide range of interests represented this year (Fig. 1). Here, we present a brief summary of the meeting, highlighting talks that generated extended discussion and posters that featured a novel approach or question. We focus on three themes that emerged across many sessions: learning, motor control of hand movements and holding still, and the advantages of a neural population activity perspective. This year's NCM began with a satellite session centered on sensory control of movement, which covered proprioception, vision, the combination of proprioception and vision, and the clinical application of basic knowledge on these topics in a variety of disorders. Jonathan Cole (Bournemouth University, England) and Fabrice Sarlegna (Aix-Marseille University, France) talked about the importance of proprioception using the dramatic example of deafferented patients. Cole presented a number of studies he did with Ian Waterman, a patient who lost all proprioception and touch below level C3, but still had intact motor function (Cole, 1995). He also retained temperature, pain, and fatigue sensation. Remarkably, Mr. Waterman soon realized that he could control his limbs based on vision, learning to walk and hold heavy objects in the absence of proprioceptive or tactile feedback. He can even perform such challenging tasks as matching the force exerted with both hands, in the presence of visual feedback (Cole & Sedgwick, 1992). He can also perceive weight differences, most likely by detecting the level of muscle fatigue. An alternative explanation, which Cole and his collaborators have not been able to rule out, is that he is detecting changes in central drive. Interestingly, Waterman is better at purely visually guided motor tasks than control subjects. For example, he outperformed controls during a mirror drawing task, probably because he did not suffer from incongruent visual and proprioceptive input (Miall & Cole, 2007). Besides residual sensation and visual feedback, he seems to rely heavily on cognitive strategies for moving and interacting with the environment. Accordingly, his ability to perform rhythmic movements degrades when asked to simultaneously perform another attention-demanding task (Lajoie et al., 1996). Cole's talk highlighted how the study of deafferented patients is a very powerful way to examine the role of sensory pathways in motor control and motor learning. Additional proof of the integral role of sensory pathways in motor learning was presented by Sarlegna. He focused his talk on motor learning in deafferented patients. It had been shown previously that visual feedback is not necessary to learn new dynamics in a force field task (Franklin et al., 2007), but Sarlegna asked whether proprioceptive feedback is needed (Sarlegna et al., 2010). Participants sat on a rotating platform and were required to reach to visual targets while a novel Coriolis force perturbed their movements. The deafferented patient learned the task as well as controls, showing similar time course and magnitude of adaptation. This shows that proprioceptive input helps improve movement quality, but is not critical for sensorimotor adaptation. Indeed, proprioception may even be detrimental in the case of incongruent feedback, as shown by Cole. There still remain open questions about how different sensory pathways interact during motor learning. Simon Gandevia (Pr