Long-Term Retention Explained by a Model of Short-Term Learning in the Adaptive Control of Reaching

Abstract

Joiner WM, Smith MA. Long-term retention explained by a model of short-term learning in the adaptive control of reaching. J Neurophysiol 100: 2948 -2955, 2008. First published September 10, 2008 doi:10.1152/jn.90706.2008. Extensive theoretical, psychophysical, and neurobiological work has focused on the mechanisms by which short-term learning develops into long-term memory. Better understanding of these mechanisms may lead to the ability to improve the efficiency of training procedures. A key phenomenon in the formation of long-term memory is the effect of over learning on retentiondiscovered by Ebbinghaus in 1885: when the initial training period in a task is prolonged even beyond what is necessary for good immediate recall, long-term retention improves. Although this over learning effect has received considerable attention as a phenomenon in psychology research, the mechanisms governing this process are not well understood, and the ability to predict the benefit conveyed by varying degrees of over learning does not yet exist. Here we studied the relationship between the duration of an initial training period and the amount of retention 24 h later for the adaptation of human reaching arm movements to a novel force environment. We show that in this motor adaptation task, the amount of long-term retention is predicted not by the overall performance level achieved during the training period but rather by the level of a specific component process in a multi-rate model of short-term memory formation. These findings indicate that while multiple learning processes determine the ability to learn a motor adaptation, only one provides a gateway to long-term memory formation. Understanding the dynamics of this key learning process may allow for the rational design of training and rehabilitation paradigms that maximize the long-term benefit of each session.

Formation of a long-term memory for visuomotor adaptation following only a few trials of practice

“…2D]. We did observe a trend for the initial bias on day 2 to increase with the amount of initial exposure on day 1, in line with previous observations (Joiner and Smith 2008). This effect is unlikely, however, to account for the overall savings we observed.…”

“…Theories regarding the formation of savings in adaptation tasks commonly assume that extended practice is required to instill a memory (Brashers-Krug et al 1996;Smith et al 2006;Braun et al 2009 ;Huang et al 2011;Joiner and Smith 2008). Knowing the lower bound on the duration of initial experience with a rotation required to obtain savings could provide important insight into the nature of the memory formed.…”

“…First is retention of adapted behavior, expressed as a reach direction bias on the first trial of the second exposure (Joiner and Smith 2008;Criscimagna-Hemminger and Shadmehr 2008). Second, and of primary interest to us, is savings, in the form of a faster relearning rate (Zarahn et al 2008).…”

“…Comparison of the biases across groups ROT 0 , ROT 5 , and ROT 5MIN did show marginal significance [bias: ANOVA, F(2,27) ϭ 3.37, P ϭ 0.051; Fig. 3C] likely due to the comparatively short interval between the initial and second adaptation sessions in ROT 5MIN , increasing residual bias in this group (Joiner and Smith 2008). Asymptotic performance on either day 2 or session 2 was not significantly different among these comparison groups [ANOVA,F(2,27) ϭ 1.41, P ϭ 0.26].…”

Automated Feedback Selection for Robot-Assisted Training

“…Findings of prediction models that generalize to new subjects could help to improve feedback designs. Researchers often conclude in their data analyses that certain measures can be used to predict the degree of motor learning (Joiner & Smith, 2008;Wu, Miyamoto, Castro, Ölveczky, & Smith, 2014). However, we have not found any literature that creates predictive models of such a finding, and quantifies generalization to new subjects in new experiments.…”