Event Abstract

Force planning depends on experiencing object weight during lift but not holding

  • 1 KU Leuven, Department of Kinesiology, Belgium
  • 2 UCL, Institute of Neurology, United Kingdom

Skilled object manipulation requires the planning of a motor command appropriate to the object properties. For instance, to lift an object, fingertip forces must be scaled according to object weight. To ensure a smooth lifting motion, the brain plans these forces before lift onset and, if necessary, adjusts the force output based on rapid sensory feedback loops during the lifting phase. When lifting a series of different objects, the planning of fingertip forces are influenced by the weight of the previous object, an effect often referred to as sensorimotor memory. In this study, we investigated whether force planning is based on a sensorimotor memory of the previous object weight that can be experienced either during the dynamic lifting phase or during the static holding phase. We used a virtual reality environment to manipulate object weight after lifting had commenced. Participants (N=9) lifted a semi-randomized series of objects that could decrease or increase in weight during the holding phase. For instance, a light object lift could be followed by a heavy object holding or, conversely, a heavy object lift could be followed by a light object holding. We analysed the effect of object weight changes on fingertip force rates applied on the next object lift as a way to quantify motor planning and compared them to control trials in which object weight was not altered. This allowed us to test whether sensorimotor memories used for force planning rely more on the dynamic lifting phase or the static holding phase. We found that force planning was based on the previous object weight experienced during the lifting phase (p’s<0.02), but not during the holding phase (p’s>0.37). This indicates that sensorimotor memory is generated by collecting information about weight over a transient period. We suggest the lifting phase is a key time period for mediating sensorimotor memory. The comparison between expected and actual sensory inputs that take place within this time period could be more critical than information acquired during static holding for building up an object representation that can be used for the planning of future interactions with objects.

Acknowledgements

VVP and MD are funded by a Fonds Wetenschappelijk Onderzoek grant to MD (FWO Odysseus, Belgium FWO: G/0C51/13N). MD is funded by a BBSRC David Phillips fellowship (UK) to MD (BBSRC: BB/J014184/1).

Keywords: Sensorimotor memory, grasping, Lifting, Object weight, force control, Motor planning

Conference: 12th National Congress of the Belgian Society for Neuroscience, Gent, Belgium, 22 May - 22 May, 2017.

Presentation Type: Poster Presentation

Topic: Sensory and Motor Systems

Citation: Van Polanen V and Davare M (2017). Force planning depends on experiencing object weight during lift but not holding. Front. Neurosci. Conference Abstract: 12th National Congress of the Belgian Society for Neuroscience. doi: 10.3389/conf.fnins.2017.94.00016

Received: 02 May 2017; Published Online: 30 May 2017.

* Correspondence: PhD. Vonne Van Polanen, KU Leuven, Department of Kinesiology, Leuven, Belgium, vonne.vanpolanen@kuleuven.be

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