The effect of encoding and retrieval on the mechanism of item + context binding
Xin XIAO, 春彦 郭, JinHong GUO ChunYan DING · Chinese Science Bulletin (Chinese Version) · 2011
To investigate the neural mechanism of semantic representation and color context binding, EEG (Electroencephalograph) time frequency and coherence analyses were used to reveal local and long-range functional coupling in the encoding and retrieval phases of episodic memory. Fifteen undergraduates participated in the experiment and middle-frequency double-character Chinese words were used as stimuli in two types of study-test tasks (context recall and context recognition tests). Significant differences between item + context and item in the encoding phase were observed at the electrodes in the frontal region during 600?800 ms by the time frequency analysis. More differences at 800 ms were obtained by ICA analyses: the frontal component as well as the coherent component of triangle phase locking structure between prefrontal, right parietal and left parietal-occipital regions. Furthermore, in the retrieval phase, the differences were obtained on the electrodes at central parietal and parietal-occipital regions at 400 ms by time frequency analysis, on parietal-occipital component at 800 ms by ICA analysis, and on coherence component of anterior right hemisphere and parietal-occipital regions at 1400 ms. In conclusion, we confirmed the different effects of encoding and retrieval processing on 'binding', which was reflected by the different extent of brain regions engaging in the cognitive operations. Especially in retrieval phase, activities of parietal-occipital region were specifically associated with'binding', and coherence between frontal and temporal-parietal regions is a common brain activity in episodic memory.