Collaborative Research: Sensorimotor control of hand-object interactions

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How people use their hands to interact with objects is one of the most complex and least understood sensorimotor skills. For example, when people pick up the same object multiple times they use different fingertip forces to compensate for differences in their fingertip positions. This compensation is important because it allows people to manipulate an object skillfully without having always to grasp it at the exact same points. Several important questions remain: What is the relative contribution of individual sensory modalities, such as touch and vision, in enabling the compensatory modulation of fingertip force and position? Are fingertip forces and positions represented separately by the central nervous system? What are the mechanisms underlying their generalization to different limbs or tasks? These questions represent a major gap in our understanding of how the central nervous system learns, plans, and executes complex motor behaviors. An understanding of how sensory modalities are seamlessly integrated to enable the development and implementation of high-level internal representations of hand-object interactions should inspire the design of more dexterous robotic manipulators endowed with sensory feedback, improve neuroprosthetics, and aid development of advanced bioengineering research tools to quantify biological control mechanisms.The overall goal of this collaborative research is to elucidate the mechanisms responsible for building high-level representations of hand-object interactions accounting for end-effector position and force. The aims are 1) to quantify the mechanisms underlying the weighting of sensorimotor integration during hand-object interactions and 2) to determine the principles underlying generalization of a learned hand-object interaction to a new context. The investigators will test three hypotheses: 1) the weighting of different sensory modalities is time dependent according to its role within a given task epoch; 2) co-variation between end-effector force and position is a general feature of hand-object interactions, independent of the effectors used (fingertip, whole hand, or two-hands); and 3) generalization of learned hand-object interactions is sensitive to the frame of reference in which they were learned.