Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, 4072 Queensland, Australia,
School of Psychology, Curtin University, Bentley, 6102 Western Australia, Australia, and.
J Neurosci. 2020 Apr 8;40(15):3075-3088. doi: 10.1523/JNEUROSCI.1506-19.2020. Epub 2020 Feb 6.
Traditional views of sensorimotor adaptation (i.e., adaptation of movements to perturbed sensory feedback) emphasize the role of automatic, implicit correction of sensory prediction errors. However, latent memories formed during sensorimotor adaptation, manifest as improved relearning (e.g., savings), have recently been attributed to strategic corrections of task errors (failures to achieve task goals). To dissociate contributions of task errors and sensory prediction errors to latent sensorimotor memories, we perturbed target locations to remove or enforce task errors during learning and/or test, with male/female human participants. Adaptation improved after learning in all conditions where participants were permitted to correct task errors, and did not improve whenever we prevented correction of task errors. Thus, previous correction of task errors was both necessary and sufficient to improve adaptation. In contrast, a history of sensory prediction errors was neither sufficient nor obligatory for improved adaptation. Limiting movement preparation time showed that the latent memories driven by learning to correct task errors take at least two forms: a time-consuming but flexible component, and a rapidly expressible, inflexible component. The results provide strong support for the idea that movement corrections driven by a failure to successfully achieve movement goals underpin motor memories that manifest as savings. Such persistent memories are not exclusively mediated by time-consuming strategic processes but also comprise a rapidly expressible but inflexible component. The distinct characteristics of these putative processes suggest dissociable underlying mechanisms, and imply that identification of the neural basis for adaptation and savings will require methods that allow such dissociations. Latent motor memories formed during sensorimotor adaptation manifest as improved adaptation when sensorimotor perturbations are reencountered. Conflicting theories suggest that this "savings" is underpinned by different mechanisms, including a memory of successful actions, a memory of errors, or an aiming strategy to correct task errors. Here we show that learning to correct task errors is sufficient to show improved subsequent adaptation with respect to naive performance, even when tested in the absence of task errors. In contrast, a history of sensory prediction errors is neither sufficient nor obligatory for improved adaptation. Finally, we show that latent sensorimotor memories driven by task errors comprise at least two distinct components: a time-consuming, flexible component, and a rapidly expressible, inflexible component.
传统的感觉运动适应观点（即，对受扰感觉反馈的运动进行适应）强调自动、隐式的感觉预测误差修正的作用。然而，最近，在感觉运动适应过程中形成的潜在记忆（例如，改进的再学习（即节省））归因于对任务错误（未能达到任务目标）的策略性修正。为了区分任务错误和感觉预测误差对潜在感觉运动记忆的贡献，我们在学习和/或测试期间扰动目标位置，以在学习期间去除或强制任务错误，有男性/女性人类参与者。在允许参与者纠正任务错误的所有条件下，适应在学习后都得到了改善，而当我们阻止任务错误的纠正时，适应并没有得到改善。因此，之前对任务错误的修正既是必要的，也是提高适应的充分条件。相比之下，感觉预测误差的历史既不是改进适应的充分条件，也不是必需条件。限制运动准备时间表明，通过学习纠正任务错误驱动的潜在记忆至少有两种形式：一个耗时但灵活的组件，以及一个快速表达但不灵活的组件。结果为这样一种观点提供了强有力的支持，即未能成功实现运动目标驱动的运动修正为表现为节省的运动记忆奠定了基础。这种持久的记忆不仅由耗时的策略性过程介导，还包括一个快速表达但不灵活的组件。这些假定过程的独特特征表明存在可分离的潜在机制，并且意味着识别适应和节省的神经基础将需要允许这种分离的方法。在感觉运动适应期间形成的潜在运动记忆在再次遇到感觉运动干扰时表现为更好的适应。相互矛盾的理论表明，这种“节省”是由不同的机制支撑的，包括对成功动作的记忆、对错误的记忆或校正任务错误的瞄准策略。在这里，我们表明，学习纠正任务错误足以显示出相对于新手表现的后续适应的改善，即使在没有任务错误的情况下进行测试也是如此。相比之下，感觉预测误差的历史既不是提高适应的充分条件，也不是必需条件。最后，我们表明，由任务错误驱动的潜在感觉运动记忆至少由两个不同的组件组成：一个耗时、灵活的组件，和一个快速表达、不灵活的组件。
