The Effect of low frequency oscillation phase on memory encoding

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Jalali, Afrooz
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta : University of Lethbridge, Dept. of Neuroscience
Oscillatory activity is a ubiquitous property of brain signals. The importance of the phase of EEG for processing naturalistic stimuli, which have typically long duration, is still not clear. In this study, we presented word-nonword pairs, each of which was visible for five seconds and measured the effect of EEG phase during stimulus onset on later memory recall. The task consisted of an encoding phase in which 20 word-nonword pairs were presented, followed by a testing phase in which subjects where shown one of the seen words with four target nonwords to choose from. We found that memory recall performance was higher when the words during encoding were presented at a descending phase of the theta oscillation. This effect was the strongest over the frontal cortex. These results suggest that the phase of ongoing cortical activity can affect memorization of persistent stimuli which are an integral part of daily tasks.
EEG , memory encoding , low frequency oscillation phase , Memory--Research , Memory--Physiological aspects , Theta rhythm , Electroencephalography , Hippocampus (Brain) , Neocortex , Oscillations