Tallon-Baudry C, Bertrand O, Peronnet F, Pernier J
Mental Processes and Brain Activation Laboratory, Institut National de la Santé et de la Recherche Médicale u280, F-69003 Lyon, France.
J Neurosci. 1998 Jun 1;18(11):4244-54. doi: 10.1523/JNEUROSCI.18-11-04244.1998.
It has been hypothesized that visual objects could be represented in the brain by a distributed cell assembly synchronized on an oscillatory mode in the gamma-band (20-80 Hz). If this hypothesis is correct, then oscillatory gamma-band activity should appear in any task requiring the activation of an object representation, and in particular when an object representation is held active in short-term memory: sustained gamma-band activity is thus expected during the delay of a delayed-matching-to-sample task. EEG was recorded while subjects performed such a task. Induced (e.g., appearing with a jitter in latency from one trial to the next) gamma-band activity was observed during the delay. In a control task, in which no memorization was required, this activity disappeared. Furthermore, this gamma-band activity during the rehearsal of the first stimulus representation in short-term memory peaked at both occipitotemporal and frontal electrodes. This topography fits with the idea of a synchronized cortical network centered on prefrontal and ventral visual areas. Activities in the alpha band, in the 15-20 Hz band, and in the averaged evoked potential were also analyzed. The gamma-band activity during the delay can be distinguished from all of these other components of the response, on the basis of either its variations or its topography. It thus seems to be a specific functional component of the response that could correspond to the rehearsal of an object representation in short-term memory.
有一种假说认为，视觉对象在大脑中可能由在伽马波段（20 - 80赫兹）以振荡模式同步的分布式细胞集合来表征。如果这个假说正确，那么在任何需要激活对象表征的任务中，尤其是当对象表征在短期记忆中保持活跃时，应该会出现振荡伽马波段活动：因此，在延迟匹配样本任务的延迟期间预计会有持续的伽马波段活动。在受试者执行此类任务时记录脑电图。在延迟期间观察到了诱发的（例如，每次试验潜伏期有抖动出现）伽马波段活动。在不需要记忆的对照任务中，这种活动消失了。此外，在短期记忆中对第一个刺激表征进行复述时的这种伽马波段活动在枕颞电极和额叶电极处均达到峰值。这种地形图与以额叶前部和腹侧视觉区域为中心的同步皮层网络的概念相符。还分析了阿尔法波段（15 - 20赫兹波段）和平均诱发电位中的活动。基于其变化或地形图，延迟期间的伽马波段活动可以与反应的所有其他这些成分区分开来。因此，它似乎是反应的一个特定功能成分，可能对应于短期记忆中对象表征的复述。
