Gabitov Ella, Manor David, Karni Avi
University of Haifa.
J Cogn Neurosci. 2014 Dec;26(12):2716-34. doi: 10.1162/jocn_a_00675. Epub 2014 Jun 4.
An almost universally accepted tacit expectation is that learning and memory consolidation processes must be reflected in the average brain activity in brain areas relevant to task performance. Motor cortex (M1) plasticity has been implicated in motor skill acquisition and its consolidation. Nevertheless, no consistent pattern of changes in the average signal, related to motor learning or motor memory consolidation following a single session of training, has emerged from imaging studies. Here we show that the pattern and magnitude of short-term brain activity modulations in response to task repetition, in M1, may provide a robust signature for effective motor memory consolidation processes. We studied participants during the paced performance of a finger-to-thumb opposition sequence (FOS), intensively trained a day earlier, and a similarly constructed untrained FOS. In addition to within-session "on-line" gains, most participants expressed delayed, consolidation-phase gains in the performance of the trained FOS. The execution of the trained FOS induced repetition enhancements in the contralateral M1 and bilaterally in the medial-temporal lobes, offsetting novelty-related repetition suppression effects. Moreover, the M1 modulations were positively correlated with the magnitude of each participant's overnight delayed gains but not with absolute performance levels. Our results suggest that short-term enhancements of brain signals upon task repetition reflect the effectiveness of overnight motor memory consolidation. We propose that procedural memory consolidation processes may affect the excitation-inhibition balance within cortical representations of the trained movements; this new balance is better reflected in repetition effects than in the average level of evoked neural activity.
一个几乎被普遍接受的默认期望是，学习和记忆巩固过程必须反映在与任务表现相关的脑区的平均脑活动中。运动皮层（M1）可塑性与运动技能习得及其巩固有关。然而，成像研究并未发现单次训练后与运动学习或运动记忆巩固相关的平均信号变化的一致模式。在这里，我们表明，M1中对任务重复的短期脑活动调制的模式和幅度可能为有效的运动记忆巩固过程提供一个可靠的标志。我们在参与者进行手指对拇指对掌序列（FOS）的节奏性表现时对他们进行了研究，该序列在一天前进行了强化训练，以及一个结构相似的未训练的FOS。除了在训练期间的“在线”进步外，大多数参与者在训练后的FOS表现中表现出延迟的巩固阶段进步。执行训练后的FOS会在对侧M1以及双侧内侧颞叶中诱导重复增强，抵消与新奇性相关的重复抑制效应。此外，M1调制与每个参与者夜间延迟进步的幅度呈正相关，但与绝对表现水平无关。我们的结果表明，任务重复时脑信号的短期增强反映了夜间运动记忆巩固的有效性。我们提出，程序性记忆巩固过程可能会影响训练动作的皮层表征内的兴奋-抑制平衡；这种新的平衡在重复效应中比在诱发神经活动的平均水平中得到更好的反映。
