Decoding of hemodynamic signals during the processing of spectral and spatial stimulus features in auditory working memory

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Working memory forms a central component of many cognitive functions and is thus fundamentally relevant to human cognition and action. Previous work has focused mainly on the ability to keep simple visual stimuli active for short time periods and to perform mental operations on them. Current research topics concern the unit of working memory storage and the question which brain regions can be considered storage regions. Previous magnetoencephalography studies from our laboratory have investigated auditory working memory, which is less well understood than visual working memory. Among our main findings were separate cortical regions for the maintenance of spatial versus nonspatial sound features. Moreover, we have assessed the prioritization of memory contents and its impact on neuronal representations in visual working memory. The present project aims at transferring current findings from the visual modality to auditory working memory and at further elucidating basic, modality-independent mechanisms of working memory. We will use decoding of functional magnetic resonance imaging data to identify auditory working memory storage regions. A series of three studies shall determine which regions fulfill the following criteria for storage regions: coding of information related to the memorized stimulus, correlation between the activation pattern and the precision of memory representations on single-trial basis, resistance of representations against distraction during the maintenance phase, and flexible prioritization of specific memory contents. We will use nonverbal sounds with variable spatial and spectral properties. Thus we can test which regions code preferentially either individual stimulus features or feature bundles. We expect that this project will enhance our knowledge about auditory working memory and provide new fundamental insights into the roles of sensory and hierarchically higher regions for the maintenance of simple and combined stimulus features.