The influence of an uncertain force environment on reshaping trial-to-trial motor variability

Jun Izawa*, Toshinori Yoshioka, Rieko Osu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Motor memory is updated to generate ideal movements in a novel environment. When the environment changes every trial randomly, how does the brain incorporate this uncertainty into motor memory? To investigate how the brain adapts to an uncertain environment, we considered a reach adaptation protocol where individuals practiced moving in a force field where a noise was injected. After they had adapted, we measured the trial-to-trial variability in the temporal profiles of the produced hand force. We found that the motor variability was significantly magnified by the adaptation to the random force field. Temporal profiles of the motor variance were significantly dissociable between two different types of random force fields experienced. A model-based analysis suggests that the variability is generated by noise in the gains of the internal model. It further suggests that the trial-to-trial motor variability magnified by the adaptation in a random force field is generated by the uncertainty of the internal model formed in the brain as a result of the adaptation.

Original languageEnglish
Pages (from-to)979-984
Number of pages6
Issue number13
Publication statusPublished - 2014 Sept 10
Externally publishedYes


  • internal model
  • motor learning
  • motor variability

ASJC Scopus subject areas

  • Neuroscience(all)


Dive into the research topics of 'The influence of an uncertain force environment on reshaping trial-to-trial motor variability'. Together they form a unique fingerprint.

Cite this