Wissing, M.B.G. (Maureen) (2019) The flexibility of synergies allow different routes of adaptive behaviour when dealing with a target switch. thesis, Human Movement Sciences.
Full text available on request.Abstract
The current study aims to understand coordination processes underlying adaptive behaviour by asking whether, and if so how, a target switch changes the synergy in which abundant degrees of freedom (DOF) are coordinated. We assumed that DOF are coordinated in a two-step process (Kay, 1988) whereby constraints: 1) act upon DOF resulting in the formation of a synergy, and 2) confine the synergy resulting in the end-effector movements. A target perturbation affects task constraints, therefore we studied whether changed constraints only confined the initial formed synergy differently (i.e., step 2) or formed a new synergy (i.e., step 1). Participants (N=12) performed discrete manual reaching movements toward a target (stationary target trials), after movement initiation the target could unexpectedly switch to a new location (switch trials). End-effector kinematics and joint angles were measured. The Uncontrolled Manifold analysis was used to assess co-variation in joint angles. To examine changes in the synergy, clusters of joint angle configurations at the beginning and end of switch trials were compared to those used in stationary target trials. Lastly, the timing of initial adjusments in the end-effector and the synergy following a target switch were compared. Results showed end-effector kinematic adjustments in switch trials. Joint angles showed primarily co-variation, indicating that DOF were synergistically organized. Clusters of joint angle configurations differed between stationary target and switch trials at movement termination, implying that the target switch evoked a change in the synergy. Finally, we found that in switch trials all participants, exhibited some trials where initial end-effector adjustments occurred before the initial change in synergy, whereas in other trials this was the other way around. The key finding was that a target switch, hence changed constraints, acted in the end always upon DOF resulting in the emerge of a new synergy. In about 70% of the trials end-effector adjustments followed from this new synergy. However, in about 30% of the trials changed constraints confined the initial formed synergy differently resulting in adjusted end-effector movements and after that a new synergy emerged. Together this implies that a synergy is flexible, and that this flexibility allows different routes for adaptive behaviour. Keywords: adaptive behaviour, coordination processes, synergies, target switch
| Item Type: | Thesis (UNSPECIFIED) |
|---|---|
| Supervisor name: | Bongers, dr. R.M. and Smith, dr. J. |
| Faculty: | Medical Sciences |
| Date Deposited: | 24 May 2022 10:08 |
| Last Modified: | 23 Sep 2022 14:40 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/3437 |
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