Binding memories. The role of brain oscillations
Advances in understanding memory mechanisms have crucial implications for cognitive neurology, and it is very good news that current studies combining multiple modalities of functional brain exploration are providing important new information. In a paper just published in the Journal of Neuroscience, Herweg et al have taken advantage of the temporal resolution provided by EEG and of the spatial information offered by functional magnetic resonance in an elegant study of recognition memory in normal individuals. They were this able to demonstrate a relationship between the low frequency oscillations (theta-alpha) typically associated with the recollection of contextual information, thus allowing the recognition of previous experiences, and an increase in functional connectivity among the hippocampus, the prefrontal cortex and the striatum. This is strong evidence supporting the increasingly influential concept of oscillations as a “binding” mechanism within large scale networks responsible for high order cognitive function. The idea, proposed by Singer and coworkers in the eighties to account for perceptual binding, is now playing a central role in the interpretation of a wide range of findings deriving from the application of increasingly complex data analysis approaches to human neurophysiological and neuroimaging data. Several pathological conditions, such as autism and schizophrenia, have been proposed as candidate “connectivity disorders”. At the practical level, these results indicate that connectivity measures derived from functional magnetic resonance, and oscillatory activity derived from EEG/MEG may represent a powerful tool to investigate normal and abnormal cognition, taking advantage of the specific strength of each method.