1. Spatiotemporal coupling of bimanual reach-to-grasp movements
Jarrod Blinch, Jon B Doan, Claudia LR Gonzalez
University of Lethbridge
motorbehaviour.wordpress.com
Making a different movement with each arm at the same time is an interesting challenge for the mind. Research has shown the dual-task of bimanual coordination is often simplified by reducing the degrees of freedom of the movements. Specifically, bimanual movements tend to follow similar spatial paths with similar timing (Kelso et al. 1979, 1983). These coordination constraints are referred to as spatial coupling and temporal coupling. We previously investigated the temporal and spatial coupling of bimanual pointing movements (Blinch et al. 2014). The purpose of the present study was to extend our investigations of spatiotemporal coupling to bimanual reach-to-grasp movements. Grasping movements are made by distal muscles and more proximal muscles are used for reaching movements. Distal muscles on both sides of the body are less interconnected in the central nervous system than proximal muscles (Carson 2005). We, therefore, hypothesised that the grasp component would have less spatiotemporal coupling than the reach component.
Introduction
Method, continued
Spatial coupling of the grasp
Unimanual
left & right
Bimanual
symmetric
asymmetric
Method
End
Peak
velocity (PV)
Negative peak
acceleration (NPA)
Positive peak
acceleration (PPA)
Reaction time
Results
Spatial coupling of the reach
Adding the grasps may have created the cost for bimanual symmetric movements
A larger bimanual asymmetric cost may have been deferred into the movement time
Temporal coupling of the reach-to-grasp
Conclusions
We were surprised by the transient spatial coupling of the grip apertures and not the amplitudes.
Our hypotheses are as follows.
The amplitudes were independently controlled during the first part of the movement. Specifically, there was no spatial coupling of the reach and no temporal coupling to at least negative peak acceleration.
Control of the grip apertures was simplified during this time by partial spatial coupling.
The end of the movement (after negative peak acceleration) involved independent control of the grip apertures to close on the targets.
Control during this time was simplified by temporal coupling.
BASICS 2016