Uncovering the drivers of human sensorimotor learning: EEG oscillatory manifestations of error, repetition and reward processing.

感觉运动学习是人类在一生中获得和保持有效运动行为能力的核心。计算模型工作强调了感觉预测误差和目标误差对获得新的运动行为的贡献，以及运动重复和奖励对运动记忆的长期保持的贡献。尽管如此，在我们对这些过程如何在大脑中表现出来，特别是在学习过程中大脑区域之间的功能相互作用如何变化的理解上，仍然存在着一个重要的差距。有鉴于此，我的研究的长期目标是在人类感觉运动网络的系统水平上研究与学习相关的神经可塑性。*有趣的是，越来越多的证据表明，节律性的大脑活动在涉及学习和可塑性的计算中起着关键作用。具体地说，theta频段(3-7赫兹)的神经振荡已经被证明受到感觉预测错误和目标错误的调制，而β频段(15-30赫兹)的振荡已经被证明受到运动重复和奖励的调制。我这个项目的短期目标是测试这样一个假设，即theta和beta振荡在不同的大脑网络中实例化功能交流，中介错误与重复和奖励，重要的含义是它们分别与运动行为的获得和保持有关。*在主题1中，实验将测试以下假设：theta-band振荡i)与感觉预测错误的大小相关，ii)与新运动行为的获得有因果关系，iii)取决于小脑。在主题2中，实验将检验这样的假设：β波段振荡i)反映重复和奖励所诱导的可塑性程度，ii)因果关系到保持新的运动行为，iii)受感觉预测误差的调节。一个关键因素是弥合大脑和行为之间的鸿沟，将错误、重复和奖励引起的神经反应与运动记忆的获得和保持速度联系起来。*在记录脑电(EEG)的同时，将使用目标式到达运动的视觉运动适应范例。为了建立神经反应和运动行为之间的因果联系，非侵入性脑刺激技术将被用来影响皮质活动，包括单脉冲经颅磁刺激(TMS)、重复TMS(RTMS)和经颅交流电刺激(TACS)。*我们正在获得通过非侵入性神经调节干预以有限的方式改变神经节奏的工具，有必要进行基础研究，为已知的学习媒介提供可靠的生物标志物。目前的研究着眼于填补这一空白，最终希望优化健康人群和脑损伤人群的运动学习和表现。

Sensorimotor learning is at the heart of humans' capacity to acquire and maintain efficient motor behaviour across the lifespan. Computational modeling work has highlighted the contributions of sensory prediction errors and target errors to the acquisition of a new motor behaviour, as well as the contributions of movement repetitions and rewards to the long-term retention of motor memories. Still, there remains an important gap in our understanding of how these processes manifest in the brain, and in particular how functional interactions between brain regions change during learning. In this light, the long-term objective of my research is to study learning-related neuroplasticity at the systems levels within the human sensorimotor network.****Interestingly, there is growing evidence that rhythmic brain activity plays a key role in computations involved in learning and plasticity. Specifically, neural oscillations in the theta-band (3-7 Hz) have been shown to be modulated by sensory prediction errors and target errors, whereas oscillations in the beta-band (15-30 Hz) have been shown to be modulated by movement repetitions and rewards. The short-term objective of my program is to test the hypothesis that theta and beta oscillations instantiate functional communication in distinct brain networks mediating errors vs. repetitions and rewards, with the important implication that they respectively relate to acquisition and retention of motor behaviours.****In Theme 1, experiments will test the hypothesis that theta-band oscillations i) covary with the size of sensory prediction errors, ii) causally relate to acquisition of a new motor behaviour, and iii) depend upon the cerebellum. In Theme 2, experiments will test the hypothesis that beta-band oscillations i) reflect the degree of plasticity induced by repetitions and rewards, ii) causally relate to retention of a new motor behaviour, and iii) are modulated by sensory prediction errors. A key element is to bridge the gap between brain and behaviour, relating neural responses incurred by errors, repetitions and rewards to rates of acquisition and retention of motor memories.****Paradigms of visuomotor adaptation of goal-directed reaching movements will be used while electroencephalography (EEG) is recorded. To establish a causal link between neural responses and motor behaviour, non-invasive brain stimulation techniques will be used to influence cortical activity, including single-pulse transcranial magnetic stimulation (TMS), repetitive TMS (rTMS) and transcranial alternating current stimulation (tACS).****At a time where we are garnering the tools to alter neural rhythms in a circumscribed manner through non-invasive neuromodulatory interventions, there is a need for fundamental research to provide reliable biomarkers of known mediators of learning. The present research looks to fill that gap, with the ultimate hope of optimizing motor learning and performance in both healthy and brain-injured populations.*********