Short-term episodic memory encoding in the human brain: a MEG and EEG study

Short-term memory encoding of visual patterns in the human brain refers to the formation of neural codes which can be used further in a wide range of working memory processes. In our present study reported in this paper, multichannel whole-head magnetoencephalogram and electroencephalogram were recorded from human subjects during performance of continuous 1-back comparison short-term memory tasks with pictorial stimuli. Estimation of the temporal dynamics of this process and source localization of the involved brain cortical generators was based on distributed inverse algorithms applied to the computed visual event-related fields (ERFs) and potentials (ERPs). The major time-domain electromagnetic responses related to the short-term episodic memory encoding of the presented single stimuli were estimated to start 300 ms after stimulus onset and continued until the disappearance of the stimuli. Source estimation showed a significant activation in the left inferior medial temporal lobe related to intentional encoding processes.