Kolloquiumsvortrag, Prof. Dr. Nikolai Axmacher, Institute of Cognitive Neuroscience, Department of Neuropsychologie, Ruhr University Bochum / 27.06.2016
27.06.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel: Network mechanisms of memory representations in the human brain
Abstract: How can the neural representations of specific experiences, or engrams, be identified in the human brain? Which neural properties determine the accuracy of memory traces, how are they altered in diseases that involve memory dysfunction, and can electric stimulation be used to restore them? In this talk, I will describe the neural mechanisms supporting content-specific representations in perception and memory, and how these findings shed light on early disease processes and may help developing new therapeutic approaches.
In the first part of the talk, I will present our basic framework for studying network representations in the human brain. In particular, analyzing brain oscillations and oscillatory interactions allows us to characterize regional activation patterns and mechanisms supporting inter-regional communication and plasticity. In the second part, I will describe some recent studies on network representations of memory traces. Using intracranial EEG recordings in epilepsy patients as well as simultaneous EEG/fMRI recordings in healthy participants, we found that stimulus-specific representations are reinstantiated during memory recall and spontaneously reactivated during awake resting state and sleep. As I will show in the third part, analyzing content-specific representations may be clinically relevant to identify early pathophysiology and potential new therapies in Alzheimer’s dementia. Using fMRI in genetic risk carriers for Alzheimer’s disease, we observed impaired entorhinal grid cell-like representations and altered navigational strategies. Furthermore, we found that deep brain stimulation to the medial temporal lobe may be a novel therapeutic option for ameliorating memory dysfunction; understanding the oscillatory basis of memory processes may help optimizing stimulation parameters.