Beaming memories: source localization of gamma oscillations reveals functional working memory network

Roux, F.^1,2, Mohr, H.³, Triezmielewska, J.³, Wibral, M.², Singer, W.^1,4, and Uhlhaas, P. J.^1,5
1Max-Planck Institute for Brain Research, Department of Neurophysiology, Frankfurt; ²MEG-Center, Brain Imaging Center, Johann-Wolfgang Goethe University Frankfurt; ³Department of Biological Psychology, Johann-Wolfgang Goethe University Frankfurt; ⁴Frankfurt Institute of Advanced Sciences, Johann-Wolfgang Goethe University Frankfurt; ⁵Laboratory for Clinical Neurophysiology and Neuroimaging, Johann-Wolfgang Goethe University Frankfurt

Empirical and theoretical evidence suggests that synchronous oscillatory activity may be involved in the neuronal dynamics of working-memory (WM). During WM, neuronal synchrony could act as a mechanism to maintain and manipulate encoded items once information is no longer available in the environment. In humans, most evidence linking neuronal synchrony and WM has been reported from EEG/MEG studies. However, only few EEG/MEG studies have investigated the cortical sources underlying synchronous oscillatory activity during WM.
We recorded MEG-signals from 20 healthy participants during a visual-spatial WM task. MEG signals were analysed in the time-frequency domain by means of Morlet-Wavelets. Furthermore, the sources of oscillatory activity were localized using Dynamic Imaging of Coherent Sources (DICS). Our results show a task-dependent increase of oscillatory activity in the high gamma (60-120 Hz) and theta (4-7 Hz) bands over parietal and frontal sensors. In addition, we found that the cortical sources of oscillatory activity in the gamma band seem to reflect a fronto-parietal network.

Symposium 7: Novel Source Localisation Approaches in MEG-Data: Basic and Clinical Applications
11.06.2009, 14:30-15:45
Seminarraum 11