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Abstract:
The hypothesis was tested whether event-related power shifts
in the upper alpha band are specifically related to semantic memory
processes. Subjects had to judge whether pairs of sequentially
presented words (W1 - W2) were semantically congruent. Then,
without prior warning subjects were presented the W1-words and were
asked to perform a semantic (free association) task and an episodic
(cued recall) task. A significant change in band power that
responds selectively to semantic processing demands was found for
the upper alpha band and over the left side of the scalp.
Furthermore, the results show that it is only the upper alpha band
that distinguishes between good and bad semantic memory performers
and that significant correlations between upper alpha
desynchronization and semantic memory performance was found during
that time period in which semantic processing actually takes place.
It is suggested (Klimesch, 1996) that semantic LTM is represented
by alpha oscillations in a cortico-thalamic network.
Klimesch, W. (1996) Memory processes, brain oscillations and EEG
sychronization. International Journal of Psychophysiology, 24,
61-100.
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