Gamma Power Reductions Accompany Stimulus-Specific Representations of Dynamic Events
Gamma Power Reductions Accompany Stimulus-Specific Representations of Dynamic Events
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DOI：
10.1016/j.cub.2015.01.011
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发表时间：
2015-03
期刊：
影响因子：
9.2
通讯作者：
Hui Zhang;J. Fell;B. Staresina;B. Weber;C. Elger;N. Axmacher
中科院分区：
文献类型：
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作者：
Hui Zhang;J. Fell;B. Staresina;B. Weber;C. Elger;N. Axmacher
特定刺激的神经表征依赖于分布式神经组件中的活动模式[1-4]。根据一个有影响力的观点，这些组件的特征是同步的γ-波段活动（GBA）[5-11]，反映了刺激特异性的表征[12-14]。然而，最近的研究表明，GBA与细胞活性的总量密切相关，并且可能不利于特定刺激的精确表示[15，16]。到目前为止，GBA在形成动态变化表示中的作用还不清楚。在这里，我们将表征相似性分析（RSA）[17]应用于10名术前癫痫患者的颅内脑电图（iEEG）数据，以识别刺激特异性神经表征。患者首先通过虚拟房屋学习并检索他们的路径。动态表征是通过大脑中频率特异性全局（空间）活动模式的快速变化分布来确定的。我们发现，GBA模式在成功的（但不是不成功的）检索一个序列更类似于活动在编码相同的序列相比，其他序列。各个电极对这些全局表示的贡献与各个电极中的局部相似性相关（即，RSA的时间）。此外，时间分辨RSA值与iEEG伽马功率的大小呈负相关：RSA值在伽马功率降低的时间点较高。全局和局部表示都依赖于一小部分电极。这些结果表明，特定的动态变化的刺激的行为相关的神经表征可以跟踪iEEG记录，它们与伽马功率的减少。
Neural representations of specific stimuli rely on activity patterns in distributed neural assemblies [1–4]. According to one influential view, these assemblies are characterized by synchronized gamma-band activity (GBA) [5–11] that reflects stimulus-specific representations [12–14]. However, recent studies have shown that GBA is closely correlated with the overall amount of cellular activity and may be detrimental for precise representations of specific stimuli [15, 16]. Until now, the role of GBA for the formation of dynamically changing representations has been unknown. Here, we applied representational similarity analysis (RSA) [17] to intracranial electroencephalogram (iEEG) data from ten presurgical epilepsy patients to identify stimulus-specific neural representations. Patients first learned and then retrieved their paths through virtual houses. Dynamic representations were identified by the rapidly changing distributions of frequency-specific global (spatial) activity patterns across the brain. We found that GBA patterns during successful (but not unsuccessful) retrieval of one sequence were more similar to activity during encoding of that same sequence compared to other sequences. The contribution of individual electrodes to these global representations was correlated with local similarity in individual electrodes (i.e., with RSA across time). Moreover, time-resolved RSA values were negatively correlated with the magnitude of iEEG gamma power: RSA values were higher at time points when gamma power was reduced. Both global and local representations relied on a small proportion of electrodes. These results show that behaviorally relevant neural representations of specific dynamically changing stimuli can be tracked by iEEG recordings and that they are associated with reductions of gamma power.