研究期間：10108~10207;The rises of cognitive neuroscience, together with its ever-fast developed imaging methods, have revealed new aspects of mind-brain relationships that were not observed in the literature of cognitive psychology or neuropsychology. A very good example is the recent ERP and fMRI findings that the left posterior parietal lobe is constantly activated in episodic memory retrieval. This finding is striking given that episodic memory was typically associated with the medial temporal lobe and the dorsolateral prefrontal cortex but rarely to the parietal lobe, an area that has frequently been linked to visual and spatial abilities in the literature of neuropsychology. There have been some interpretations for the functional roles of the left posterior parietal lobe in episodic memory retrieval. Among them the ‘attention-to-memory’ (AtoM) and the episodic buffer accounts are most often discussed. Both theories have obtained supportive evidence from fMRI studies. However, the issues of whether there are heterogeneous functions of the subregions in the left posterior parietal cortex and how these sub-regions interact to support episodic memory retrieval are far from clear, mainly due to the poor temporal resolution of BOLD response and the lack of interference studies to establish the causal relationship between the left posterior parietal lobe and episodic memory retrieval. The current project aims to address this issue with behavioral experiments, scalp-recorded electrophysiological signals, BOLD hemodynamic responses, and noninvasive electrical stimulation. A total of ten experiments are proposed in the current project. Experiments I and II will employ tDCS to verify the necessity of the LPPC activities in episodic memory retrieval. Experiments III and IV aim to develop an optimal protocol, based on which the role of attentional processes in episodic memory retrieval could be investigated. Experiment V aims to validate the hypothesis that the quality of episodic memory recollection can be indexed by the magnitude of the left parietal ERP old/new effect. Based on the results of the Experiments III to V, a protocol that incorporates both attention-related and episodic-buffer-related variables would be developed for Experiments VI and VII. These two experiments, which will acquire EEG/ERP and fMRI data, aim to determine the attention-to-memory and episodic-buffer accounts for the role of left posterior parietal cortex in episodic memory retrieval. Finally, the electrical stimulation of tDCS will be employed in Experiments VIII to X to establish the causal relationship between the neuronal activities of parietal lobe and the attention- or maintenance-related processes in episodic memory retrieval. It is expected that the experiments proposed here will provide convergent evidence, which will advance our understanding of elementary cognitive operations subserved by the subregions of the left posterior parietal cortex, and how these areas interact with other brain regions to support successful episodic memory retrieval.
