Prospective memory (PM) refers to memory for future intentions.Difference due to memory (Dm effect) is the difference in neural activity related to stimuli that were subsequently remembered or forgotten.Using event-related potentials (ERPs),the present study investigated the Dm effect for PM using a subsequent task-switching paradigm.The results showed that a Dm effect of ERP P150 was more positive-going for later PM hit trials than for later PM forgotten trials during 100–200 ms.This Dm effect may reflect the process for the production of future intention or the process for attention.Consistent with previously reported Dm effects of other types of memory,we found that the fbN2 (250–280 ms) and late positivity component (400–700 ms) were stronger in later PM hit trials than in forgotten trials.The fbN2 was evoked by Chinese characters.The late positivity component was related to the precise encoding process.In conclusion,because of the early P150,PM encoding appears to be somewhat different from previously identified Dm effects.However,further research is needed.Our findings reveal that Dm effects of PM share similar characteristics with known Dm effects of other types of episodic memory after the very early stage of neural processing.
To investigate the neural mechanism of semantic representation and color context binding,we used electroencephalograph time frequency and coherence analyses 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 at 600-800 ms by time frequency analysis.Further differences were observed at 800 ms by independent component analysis:the frontal component and the coherent component of the triangle phase locking structure among the prefrontal,right parietal and left parietal-occipital regions.In the retrieval phase,differences between item+context and item were found on the electrodes at the central parietal and parietal-occipital regions at 400 ms by time frequency analysis,on the parietal-occipital component at 800 ms by independent component analysis and on the coherence component of the anterior right hemisphere and parietal-occipital regions at 1400 ms.In conclusion,the different effects of encoding and retrieval processing on 'binding' are reflected by the differing extents that brain regions engaged in cognitive operations.In the retrieval phase in particular,activities of the parietal-occipital region were specifically associated with 'binding',and coherence between frontal and temporal-parietal regions is a common brain activity in episodic memory.
Explicit memory errors may occur when individuals fail to retrieve information about items previously studied (item memory) or about the learning context (source memory). We examined electrophysiological measures during recognition failure in order to determine the influence of retrieval orientation for item versus source information. Recognition failure was associated with brain potentials distinct from those associated with success. Furthermore, source-memory failures were associated with earlier-onset brain potentials with a more anterior distribution compared to item-memory failures. Neurocognitive processing was thus modulated by retrieval orientation so as to differentially influence neural correlates of successful versus unsuccessful retrieval.
GUO ChunYanCHEN WenJunTIAN TianKen A PALLERJoel L VOSS
