한국인지과학회:학술대회논문집 (Proceedings of the Korean Society for Cognitive Science Conference)
- 한국인지과학회 2010년도 춘계학술대회
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- Pages.37-41
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- 2010
The Analysis of Gamma Oscillation and Phase-Synchronization for Memory Retrieval Tasks
- Kim, Sung-Phil (Barin and Cognitive Engineering, Korea University) ;
- Choe, Seong-Hyeon (Barin and Cognitive Engineering, Korea University) ;
- Kim, Hyun-Taek (Department of Psychology, Korea University) ;
- Lee, Seung-Hwan (Department of Neuropsychiatry, Inje University)
- 발행 : 2010.05.28
초록
The previous investigations of electroencephalogram (EEG) activity in the memory retrieval tasks demonstrated that event-related potentials (ERP) during recollection showed different durations and the peak levels from those without recollection. However, it has been unknown that recollection in memory retrieval also modulates high-frequency brain rhythms as well as establishes large-scale synchronization across different cortical areas. In this study, we examined the spectral components of the EEG signals, especially the gamma bands (20-80Hz), measured during the memory retrieval tasks. Specifically, we focused on two major spectral components: first, we evaluated the temporal patterns of the power spectral density before and after the onset of the memory retrieval task; second, we estimated phase synchrony between all possible pairs of EEG channels to evaluate large-scale synchronization. Fourteen healthy subjects performed the memory retrieval task in the virtual reality environment where they selected whether or not t he present item was seen in the previous training period. When the subjects viewed the unseen items, the middle gamma power (40-60Hz) appeared to increase 200-500ms after stimulus onset while the low gamma power (20Hz) was suppressed all the way through the post-stimulus period 150ms after onset. The degree of phase synchronization in this low gamma level, however, increased when the subjects fetched the item from memory. This suggests that phase synchrony analysis might reveal different aspects of the memory retrieval process than the gamma power, providing additional information to the inference on the brain dynamics during memory retrieval.
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