Breton Jocelyn, Robertson Edwin M
Institute of Neuroscience & Psychology, Centre for Cognitive Neuroimaging, University of Glasgow, Glasgow, G12 8QB, UK.
Nat Hum Behav. 2017 Jun;1(6). doi: 10.1038/s41562-017-0111. Epub 2017 May 15.
Our brains are constantly processing past events [1]. These off-line processes consolidate memories, leading in the case of motor skill memories to an enhancement in performance between training sessions. A similar magnitude of enhancement develops over a night of sleep following an implicit task, when a sequence of movements is acquired unintentionally, or following an explicit task, when the same sequence is acquired intentionally [2]. What remains poorly understood, however, is whether these similar offline improvements are supported by similar circuits, or through distinct circuits. We set out to distinguish between these possibilities by applying Transcranial Magnetic Stimulation (TMS), over the primary motor cortex (M1) or the inferior parietal lobule (IPL) immediately after learning in either the explicit or implicit task. These brain areas have both been implicated in encoding aspects of a motor sequence, and subsequently supporting offline improvements over sleep [3-5]. Here we show that offline improvements following the explicit task are dependent upon a circuit that includes M1 but not IPL. By contrast, offline improvements following the implicit task are dependent upon a circuit that includes IPL but not M1. Our work establishes the critical contribution made by M1 and IPL circuits to offline memory processing, and reveals that distinct circuits support similar offline improvements.
我们的大脑一直在处理过去的事件[1]。这些离线过程巩固记忆，在运动技能记忆的情况下，会导致训练期间的表现得到提升。在进行隐性任务（即无意中习得一系列动作）或显性任务（即有意习得相同序列）后，经过一夜睡眠也会出现类似程度的提升[2]。然而，目前仍不清楚的是，这些类似的离线改善是由相似的神经回路支持，还是通过不同的神经回路。我们通过在显性或隐性任务学习后立即对初级运动皮层（M1）或顶下小叶（IPL）施加经颅磁刺激（TMS），来区分这些可能性。这两个脑区都与运动序列的编码有关，随后支持睡眠期间的离线改善[3-5]。在这里，我们表明，显性任务后的离线改善依赖于一个包括M1但不包括IPL的神经回路。相比之下，隐性任务后的离线改善依赖于一个包括IPL但不包括M1的神经回路。我们的研究确定了M1和IPL神经回路对离线记忆处理的关键贡献，并揭示了不同的神经回路支持类似的离线改善。
