In recent years a major goal in neuroscience has been to better understand the neuronal dynamics in cortical networks. A key issue in this topic is how input into cortical networks is processed. It is currently hotly debated how amplitude and phase of ongoing cortical neural activity are generated and modulated by input. Input into a cortical area can in general come from either the periphery (bottomup) or from "higher" cortical areas ("top-down"). The detailed mechanisms for the generation of neocortical oscillations are currently under debate. For example, some models for the generation of gamma oscillations propose an interaction of glutamatergic pyramidal cells with GABAergic interneurons (e.g. Whittington et al. 1995; Haider et al. 2006) while other models emphasize the relevance of thalamocortical loops (e.g. Llinás et al. 2002). The current project aims at resolving this issue. A further presently unresolved issue is how event-related potentials are generated. A debate exists whether the event-related potential is predominantly accounted for by phase-reset of ongoing activity
(e.g. Brandt & Jansen 1991; Makeig et al. 2002; Klimesch et al. 2004) or a stimulus-induced increase in EEG activity (e.g. Schroeder et al. 1995). In order to resolve both issues two approaches have been suggested. The first one is to perform intracranial recordings in animals which allow selective pharmacological (and other) manipulations of the cortical network (Barth & MacDonald 1996). A second approach is the explicit modelling of the amplitude and phase organization of cortical activity by biologically plausible neural networks (Destexhe et al. 1999; Izhikevich 2003). In addition, the combination of both approaches allows investigation of the relationship between microscopic (spike train) and macroscopic levels (LFP, EEG). In the present project we will use both approaches and additionally include intracranial recordings in humans.
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