| dc.description.abstract | Classical views of human visual long-term memory propose that people first encode the
visual stimuli into a long-term store, and then retrieve the visual information during task
period. In examining the temporal dynamics of visual memory encoding, previous
human electroencephalogram (EEG) recordings have shown that an increase in the
amplitude of a positive frontal event-related potential (ERP) and the suppression of
posterior alpha band (8-12 Hz) oscillations both occur during the successful encoding of
a memory. However, we do not know whether these two different signals are
functionally independent as EEG neural signatures. In this study, we used transcranial
direct current stimulation (tDCS) to dissociate these two neural signatures in human
subjects during a recognition memory task. We found that the parietal-occipital alpha
suppression, but not the time-domain frontal positivity, followed the improvement in
memory under anodal stimulation relative to when the same subjects were given sham
stimulation. Meanwhile, our experiments also show that the improvement of recognition
memory was not due to the attentional arousal of participants or a better retrieval
quality. Collectively, our findings show that the time-voltage ERP measure of memory
encoding and the alpha oscillations clearly index independent mechanisms that
contribute to how well we later remember a stimulus. | en_US |
