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Abstract:
Introduction: Although memory has frequently been studied
using ERPs, short-duration changes in the background EEG have been
largely ignored. Recent work, using Event-related desynchronisation
(ERD), have shown that there are transient changes in both the
theta and alpha frequency ranges for both verbal and face stimuli.
One limitation of ERD has been its limited temporal resolution but
new techniques are available which overcome this. The aim of this
study is to determine whether there are memory-related changes in
the EEG for non-verbal stimuli using higher temporal resolution
than before. Method: EEG was recorded from participants as they
performed a continuous recognition memory task for geometric
designs. Results: the presentation of stimulus was associated with
a sharp increase in the theta power in the first 250ms followed by
a later desynchronisation in the alpha frequency. There was no
evidence for a repetition effect in the theta range but there was
significant memory-related alpha desynchronisation. Conclusion:
This study confirms earlier work suggestin that theta
synchronization is associated with encoding into memory and alpha
desynchronization with recognition.
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