Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel.
Proc Natl Acad Sci U S A. 2023 Dec 26;120(52):e2303985120. doi: 10.1073/pnas.2303985120. Epub 2023 Dec 19.
Practicing motor skills stabilizes and strengthens motor memories by repeatedly reactivating and reconsolidating them. The conventional view, by which a repetitive practice is required for substantially improving skill performance, has been recently challenged by behavioral experiments, in which even brief reactivations of the motor memory have led to significant improvements in skill performance. However, the mechanisms which facilitate brief reactivation-induced skill improvements remain elusive. While initial memory consolidation has been repeatedly associated with increased neural excitation and disinhibition, reconsolidation has been shown to involve a poorly understood mixture of both excitatory and inhibitory alterations. Here, we followed a 3-d reactivation-reconsolidation framework to examine whether the excitatory/inhibitory mechanisms which underlie brief reactivation and repetitive practice differ. Healthy volunteers practiced a motor sequence learning task using either brief reactivation or repetitive practice and were assessed using ultrahigh field (7T) magnetic resonance spectroscopy at the primary motor cortex (M1). We found that increased inhibition (GABA concentrations) and decreased excitation/inhibition (glutamate/GABA ratios) immediately following the brief reactivation were associated with overnight offline performance gains. These gains were on par with those exhibited following repetitive practice, where no correlations with inhibitory or excitatory changes were observed. Our findings suggest that brief reactivation and repetitive practice depend on fundamentally different neural mechanisms and that early inhibition-and not excitation-is particularly important in supporting the learning gains exhibited by brief reactivation.
练习运动技能通过反复重新激活和再巩固运动记忆来稳定和增强它们。传统观点认为，要大幅度提高技能表现，就需要进行重复练习，但最近的行为实验对此提出了挑战，这些实验表明，即使是短暂地重新激活运动记忆，也能显著提高技能表现。然而，促进短暂重新激活引起的技能提升的机制仍然难以捉摸。虽然初始记忆巩固已被反复证明与神经兴奋和抑制的增加有关，但再巩固已被证明涉及到一种尚不清楚的兴奋和抑制改变的混合物。在这里，我们遵循一个 3 天的重新激活-再巩固框架，来研究支持短暂重新激活和重复练习的兴奋性/抑制性机制是否不同。健康志愿者使用短暂重新激活或重复练习来练习运动序列学习任务，并在初级运动皮层（M1）使用超高场（7T）磁共振波谱进行评估。我们发现，短暂重新激活后立即增加的抑制（GABA 浓度）和减少的兴奋/抑制（谷氨酸/GABA 比值）与夜间离线表现的提高有关。这些提高与重复练习所表现出的提高相当，在重复练习中没有观察到与抑制或兴奋变化的相关性。我们的发现表明，短暂重新激活和重复练习依赖于根本不同的神经机制，并且早期抑制——而不是兴奋——对于支持短暂重新激活所表现出的学习提高尤为重要。
