Neural correlates of control processes engaged before and during recovery of information from episodic memory

Preparing to retrieve episodic information engages content-specific pre-retrieval processes--retrieval orientations--that vary according to the episodic information that is to be retrieved [Rugg, M.D., Wilding, E.L., 2000. Retrieval processing and episodic memory. Trends Cogn. Sci. 4, 108-115]. Retrieval orientations are retrieval sets which can be maintained tonically and which influence the ways in which subsequent stimuli are processed, presumably in order to facilitate recovery of the required episodic information. Indices of processes related to the adoption of a retrieval orientation can therefore be obtained by acquiring measures of neural activity during preparation to retrieve, while processes contingent upon the successful adoption of an orientation can be obtained by measuring the neural activity that is elicited by stimuli to which memory judgments are required. Across three experiments, electrophysiological indices of the former class of process were obtained only when frequent switches between different retrieval tasks were required, confirming that this measure of brain activity reflects processes important for the adoption of a relevant retrieval orientation. Stimulus-specific indices of retrieval orientations were obtained primarily when few switches between retrieval tasks were required, consistent with the view that the engagement of stimulus-specific retrieval processing operations is achieved only when an appropriate retrieval orientation has been adopted fully.