PT  - JOURNAL ARTICLE
AU  - James Mathew
AU  - Philippe Lefevre
AU  - Frederic Crevecoeur
TI  - Rapid changes in movement representations during human reaching could be preserved in memory for at least 850ms
AID  - 10.1523/ENEURO.0266-20.2020
DP  - 2020 Sep 18
TA  - eneuro
PG  - ENEURO.0266-20.2020
4099  - http://www.eneuro.org/content/early/2020/09/18/ENEURO.0266-20.2020.short
4100  - http://www.eneuro.org/content/early/2020/09/18/ENEURO.0266-20.2020.full
AB  - Humans adapt to mechanical perturbations such as force fields during reaching within tens of trials. However, recent findings suggested that this adaptation may start within one single trial, i.e., online corrective movements can become tuned to the unanticipated perturbations within a trial. This was highlighted in previous works with a reaching experiment in which participants had to stop at a via-point (VP) located between the start and the goal. A force field was applied during the first and second parts of the movement and then occasionally unexpectedly switched off at the VP during catch trials. The results showed an after-effect during the second part of the movement when participants exited the VP. This behavioural result was interpreted as a standard after-effect, but it remained unclear how it was related to conventional trial-by-trial learning. The current study aimed to investigate how long do such changes in movement representations last in memory. For this, we have studied the same reaching task with VP in two situations: one with very short residing time in the VP and the second with an imposed minimum 500ms dwell time in the VP. In both situations, during the unexpected absence of the force field after VP, after-effects were observed. This suggests that online corrections to the internal representation of reach dynamics can be preserved in memory for around 850ms of resting time on average. Therefore, rapid changes occurring within movements can thus be preserved in memory long enough to influence trial-by-trial motor adaptation.SIGNIFICANCE STATEMENT Recent studies suggested that adaptive feedback control happens within a reach movement and the feedback responses are tuned specifically to the single-trial perturbation. Here we show that these feedback mediated changes in movement representations can last for around 850ms and are available to reproduce the characteristics of the newly acquired correction process. Current data replicate previous studies showing that feedback corrections are associated with changes in online representations, and demonstrate that these changes are preserved in memory long enough to be an important component of standard trial-by-trial adaptation.