Poster #60 - Motor Adaptation in a Daily-Based Force Adaptation Task within Early Childhood

• In Event: Poster Session 20

Abstract

In early childhood, the milestones of motor and cognitive development expand young children's abilities to interact with their environment. In this process, motor adaptation becomes important to refine the acquired motor skills and adapt them to different demands of the body and the dynamic environment (Adolph & Berger, 2007). One of the first child-specific adaptation requirements is force adaptation (e.g., grasping objects of different weights). Initial studies have investigated that children (4-6 years) exhibit mechanisms of force adaptation. Nevertheless, force adaptation is still under development, as children show slower (de)adaptation rates compared to older children and adults, and performance is accompanied by greater movement variability. In these studies, grasping movements were tested with a robotic manipulandum that applied unexpected forces to the hand that had to be compensated for (e.g., Konczak et al.; 2010; Takahashi et al., 2003). It remains unclear how force adaptation develops in earlier life and in a task that has a more prominent daily-life context. Therefore, this study examines two groups of children (18 months, 3 years) and one group of adults (20-30 years) when performing a force adaptation on a drawer.
Participants sit on an adjustable chair in front of a box and a drawer, and are asked to open the drawer several times with their right hand. The drawer has an attachable weight that allows flexible changes of drawer resistance (Figure 1). The experiment consists of three blocks of 16 trials. In the baseline block, participants get used to the force required to open the drawer with a comfortable velocity profile for the specific drawer resistance (group A begins with a drawer resistance of 5 N, group B with a high drawer resistance of 8.5 N). In the adaptation block, drawer resistance is perturbed, requiring participants to adapt their force to a new resistance (group A: 8.5 N, group B: 5 N). In the washout block, drawer resistance changes again to the baseline condition and participants deadapt their force (group A: 5 N, group B: 8.5 N).
Dependent variables are grasping position, drawer position and timing (measured by Vicon Nexus) as well as proactive and reactive muscle activation in response to force perturbation on the right arm (measured by Cometa Mini Wave). Data processing and analysis is performed in MATLAB R2022a. We use multivariate ANOVAs to test group differences and (de)adaptation performance within trials and blocks.
Figure 2 represents a hypothesized drawer velocity curve of an adult of group A. Additionally, we expect a change from reactive to proactive muscle activation with increasing adaptation. According to previous force-adaptation studies, we hypothesize that adaptation performance will be improved with increasing age, which means faster (de)adaptation and higher aftereffects in response to force perturbation. Importantly, we also expect adaptation for the youngest children, since adaptation already plays a crucial role at the beginning of life (e.g. opening a drawer with changed resistance). Our study contributes to the development of motor adaptation and the accompanied internal model formation at the beginning of the lifespan.

Authors

• Laura Fassbender, Justus-Liebig-Universität Gießen
  Presenting Author

• Johannes Falck

• Yee Lee Shing, Goethe University Frankfurt

• Bianca Jovanovic, University of Giessen

• Gudrun Schwarzer, University of Giessen