Wie das synchronisierte Gehirn Langzeitgedächtnisinhalte formt
Memories are stored within the synaptic connections between neural assemblies. These connections are being formed by synchronous firing, which is mediated by brain oscillations that can be recorded non-invasively in humans by means of MEG/EEG. Brain oscillations should thus be a key mechanism for the encoding of long-term memories. However, at the moment little is known about how these mechanisms work in the human brain. Therefore the goal of the proposed research plan is to investigate the role of neural synchronization for the formation of long-term memories in a series of experiments. Derived from cognitive theories of long-term memory, those experiments are aimed at dissociating synchronous memory networks at the time memories are being formed. Moreover it will be investigated, how the reactivation of those very same networks supports memory retrieval. By means of electrophysiological recordings (MEG/EEG) and functional brain imaging, the dynamics of oscillatory brain networks will be elucidated comprehensively. On the basis of these empirical data, a neuro-cognitive memory model will be developed, which incorporates the observed brain oscillatory dynamics. Moreover, neuroplasticity studies will be conducted to show how those networks are shaped by intense training. These may be valuable for the development of neurocognitive therapeutic interventions for memory disorders (e.g. dementia).
- FB Psychologie
|(2012): Prefrontally Driven Downregulation of Neural Synchrony Mediates Goal-Directed Forgetting Journal of Neuroscience ; 32 (2012), 42. - S. 14742-14751. - ISSN 0270-6474. - eISSN 1529-2401|
Neural synchronization between distant cell assemblies is crucial for the formation of new memories. To date, however, it remains unclear whether higher-order brain regions can adaptively regulate neural synchrony to control memory processing in humans. We explored this question in two experiments using a voluntary forgetting task. In the first experiment, we simultaneously recorded electroencephalography along with fMRI. The results show that a reduction in neural synchrony goes hand-in-hand with a BOLD signal increase in the left dorsolateral prefrontal cortex (dlPFC) when participants are cued to forget previously studied information. In the<br />second experiment, we directly stimulated the left dlPFC with repetitive transcranial magnetic stimulation during the same task, and show that such stimulation specifically boosts the behavioral forgetting effect and induces a reduction in neural synchrony. These results suggest that prefrontally driven downregulation of long-range neural synchronization mediates goal-directed forgetting of long-term memories.
|(2012): Rapid memory reactivation revealed by oscillatory entrainment. Current Biology ; 22 (2012), 16. - S. 1482-1486. - ISSN 0960-9822. - eISSN 1879-0445|
Episodic memory refers to humans' unique ability to mentally reconstruct past events. Neurocomputational models predict that remembering entails the reinstatement of brain activity that was present when an event was initially experienced [ , , ,  and ], a claim that has recently gained support from functional imaging work in humans [ , , , , , , ,  and ]. The nature of this reactivation, however, is still unclear. Cognitive models claim that retrieval is set off by an early reactivation of stored memory representations (“ecphory”) [ ,  and ]. However, reinstatement as found in imaging studies might also reflect postretrieval processes that operate on the products of retrieval and are thus a consequence rather than a precondition of remembering. Here, we used frequency entrainment as a novel method of tagging memories in the human electroencephalogram (EEG). Participants studied words presented on flickering backgrounds, entraining a steady-state brain response at either 6 or 10 Hz. We found that these frequency signatures rapidly reemerged during a later memory test when participants successfully recognized a word. An additional behavioral experiment suggested that this reactivation occurs in the absence of conscious memory for the frequencies entrained during study. The findings provide empirical evidence for the role of rapid, likely unconscious memory reactivation during retrieval.
|Emmy-Noether-Programm||597/10||HA 5622/1-1||02.07.2010 – 01.07.2013|
|Period:||01.09.2010 – 31.08.2015|