Decrease in gamma-band activity tracks sequence learning.
Decrease in gamma-band activity tracks sequence learning.
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DOI：
10.3389/fnsys.2014.00222
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发表时间：
2014
影响因子：
3
通讯作者：
Anderson WS
中科院分区：
文献类型：
--
作者：
Madhavan R;Millman D;Tang H;Crone NE;Lenz FA;Tierney TS;Madsen JR;Kreiman G;Anderson WS
学习新的序列构成了陈述性记忆形成的一个例子，涉及有意识地回忆时间事件。在序列学习任务中的表现随着重复而提高，并涉及在秒到分钟的尺度上形成时间关联。为了进一步了解陈述性序列学习的神经回路，我们跟踪了14名人类受试者的1142个植入颞叶和额叶皮层区域的电极记录的颅内场电位（IFP）的变化，同时他们通过重复回忆学习了多个图像序列的时间顺序。我们观察到，在回忆阶段，伽玛频带（30-100赫兹）的功率增加，特别是在颞叶内的区域，包括海马旁回。这种伽马功率增强的程度随着序列回忆的改善而降低。伽马功率的调制与回忆性能的改善直接相关。当呈现新序列时，伽马功率被重置为高值，并在学习后再次降低。这些观察结果表明，伽马频带中的信号可能在学习过程的早期阶段而不是在记忆痕迹的维持过程中发挥更突出的作用。
Learning novel sequences constitutes an example of declarative memory formation, involving conscious recall of temporal events. Performance in sequence learning tasks improves with repetition and involves forming temporal associations over scales of seconds to minutes. To further understand the neural circuits underlying declarative sequence learning over trials, we tracked changes in intracranial field potentials (IFPs) recorded from 1142 electrodes implanted throughout temporal and frontal cortical areas in 14 human subjects, while they learned the temporal-order of multiple sequences of images over trials through repeated recall. We observed an increase in power in the gamma frequency band (30–100 Hz) in the recall phase, particularly in areas within the temporal lobe including the parahippocampal gyrus. The degree of this gamma power enhancement decreased over trials with improved sequence recall. Modulation of gamma power was directly correlated with the improvement in recall performance. When presenting new sequences, gamma power was reset to high values and decreased again after learning. These observations suggest that signals in the gamma frequency band may play a more prominent role during the early steps of the learning process rather than during the maintenance of memory traces.