Current Project
Institute of Medical Psychology

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

Jochen Kaiser and Christoph Bledowski

Supported by the German Research Foundation (DFG grant KA 1493/7-1 and BL 931/4-1, 2016-2019)

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.

The influence of synchronous physical activity on brain plasticity and foreign language learning

Maren Schmidt-Kassow

Supported by the German Research Foundation (DFG grant SCHM 2693/1-1, 1-2, 2010-2018)

Numerous studies have provided evidence that physical activity promotes cortical plasticity in the adult brain via enhanced levels of the messenger BDNF (brain derived neurotrophic factor). Furthermore, BDNF has been shown to correlate positively with performance during vocabulary learning. However, until now, the effect of synchronous physical activity (e.g. bicycling) on learning performance has not been investigated systematically. Recent data however suggest that the positive relationship between physical exercise and encoding in long-term memory can be enhanced further when learning and motor activity are synchronized, i.e. when synchronous motor activity increases the temporal predictability of to-be-memorized information. The current project aims at clarifying which kind of physical activity maximally facilitates long-term memory processing and which role the exact timing of activity plays. To answer this question we aim to combine approaches from different disciplines. Thus, we will assess structural changes of brain areas involved in vocabulary learning as well as electrophysiological responses to memorized materials. In addition, physiological parameters will be collected to obtain a comprehensive and detailed picture of the influence of synchronous physical activity on verbal learning.

Automatized actions in nicotine dependence: Neural and behavioral correlates and their malleability by abstinence

Yavor Yalachkov, Jochen Kaiser and Marcus Naumer

Supported by the German Research Foundation (DFG grant YA 335/2-1, 2013-1015)

Neuronal correlates of focus updating in working memory

Christoph Bledowski and Jochen Kaiser

Supported by the German Research Foundation (DFG grant BL 931/3-1, 2011-2014)

Cognition depends critically on working memory (WM), i.e. the active representation of a limited number of items over a short period of time. Many studies suggested a close association between WM and attention, including shared capacity limitations and common neural organization. Indeed, WM can be regarded as emerging from the functional interaction of attentional and memory systems. In addition to the pure retention of information in the course of cognitive processing, many tasks require that some of the items in WM become transiently more important than others. For example, recent neuroimaging findings have demonstrated that updating or shifting the attentional focus toward a task-relevant WM item recruits frontal and parietal regions that have previously been related to visual attention. Even though the operation of focus updating may be the fundamental operation for prioritization of items in WM as a core prerequisite for higher-order cognitive functions, important characteristics of its functional and neuroanatomical properties are still unspecified. Here we propose a series of behavioral and neuroimaging studies that seek to specify the functional and neuronal characteristics of focus updating in WM in space and time using functional magnetic resonance imaging and magnetoencephalography. In particular, we will investigate the neuronal effects of internal versus external and spatial versus object-based focus updating by systematic variation of a common basis paradigm that we have recently developed. Moreover, we will also examine the modulatory effect of WM focus updating on the activation of early visual areas, which were recently shown to be recruited in the course of the retention of visual information in WM.