Changes in local gamma power and functional connectivity with consolidation of declarative memory

Nieuwenhuis, I. L. C., Takashima, A., Oostenveld, R., Fernández, G., and Jensen, O.
Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, The Netherlands

System-level consolidation involves a gradual reorganization of brain regions that support memory. Initially declarative memories depend on the hippocampus. Over time memory traces are incorporated into neocortical storage areas. Using magnetoencephalography (MEG) we investigated the effect of memory consolidation on gamma band activity in neocortical memory areas. We measured brain activity during retrieval of remote and recent memories. We performed time-frequency analysis of power using multi-taper methods and a beamforming analysis was applied to identify the sources. Strong induced gamma band activity (>60 Hz) was observed during retrieval in both conditions. Gamma power was higher during recall of remote memories, in visual, temporal and parietal brain areas. We also investigated the correlation over trials of gamma power between brain areas as a measure of cortico-cortical functional connectivity on source level. These results demonstrate a functional change in neocortical networks with memory consolidation as reflected by changes in gamma band activity.

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