Function and relevance of oscillatory prestimulus activity for the formation of memory

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In the recent years the relevance of specific brain activity before the presentation of the actual stimulus has been demonstrated in several studies and for several cognitive processes.As in an own pilot study also other studies have shown an influence of different neuronal prestimulus activity also for the formation of memory. In summary, oscillatory activity in different frequencies was related to the quality of memory for the subsequent processed stimulus. However, it remains unclear what psychological factors were represented by the different activities and how strong the relevance of the different oscillations is for the formation of memory. It is postulated that different factors affected the prestimulus activity but that at least one factor is supposed to be specific for the subsequent information processing and should be incorporated as a relevant process for the memory process. The experimental designs of previous studies used cues that informed the participants about the presentation of the actual stimulus and thereby enabled a conscious preparation for the actual stimulus processing. Therefore, the prestimulus activity is also a cue evoked activity and reflects different processes like attention, motivation and specific encoding strategies.The aim of the actual project is the identification of the different psychological factors and the differentiation of the neuronal effects. The assignment of neuronal effects in different frequency bands to psychological described information processing factors should be achieved by the presence and manipulation of the information of cue stimuli.Therefore, the information of the cue is manipulated via the instruction to influence differentially processes like attention or the activation of encoding strategies. The neural correlates of the different processes will be assessed with EEG measurements. The comparison to experimental settings without a cue stimulus is important to determine relevant prestimulus activity without the influence of cue evoked activity.The specificity of the neuronal activity within the prestimulus period for the used material will be estimated by the analysis of common and different effects for acoustic and visual memory formation.The functional relevance of the different processes will be tested by adaptive stimulus presentation in well described states of neuronal activity and by modulation of neuronal activity using neurofeedback approaches with an already established brain- computer interface. Finally, the neuronal sources of the relevant oscillations will be estimated by combined EEG- fMRT measurements in more detail.