Independent delta/theta rhythms in the human hippocampus and entorhinal cortex

Frontiers in Human Neuroscience

Bernd Weber¹  Juergen Fell¹  Christian E Elger¹  Ralph G Andrzejak²  Florian Mormann³  Guillén Fernández⁴  Klaus Lehnertz⁵  Hannes Osterhage⁵ 

[1] Department of Epileptology, University of Bonn;Department of Information and Communication Technologies, University Pompeu Fabra;Division of Biology, California Institute of Technology;F.C. Donders Center for Cognitive Neuroimaging and Departement of Neurology, Radboud University Nijmegen;Helmholtz-Institute for Radiation and Nuclear Physics, University of Bonn;

关键词: synchronization;    oscillations;    Wavelet;    intracranial EEG;    medial temporal lobe;    phase precession;   

DOI  :  10.3389/neuro.09.003.2008

来源: DOAJ

【 摘 要 】

Theta oscillations in the medial temporal lobe (MTL) of mammals are involved in various functions such as spatial navigation, sensorimotor integration, and cognitive processing. While the theta rhythm was originally assumed to originate in the medial septum, more recent studies suggest autonomous theta generation in the MTL. Although coherence between entorhinal and hippocampal theta activity has been found to influence memory formation, it remains unclear whether these two structures can generate theta independently. In this study we analyzed intracranial electroencephalographic (EEG) recordings from 22 patients with unilateral hippocampal sclerosis undergoing presurgical evaluation prior to resection of the epileptic focus. Using a wavelet-based, frequency-band-specific measure of phase synchronization, we quantified synchrony between 10 different recording sites along the longitudinal axis of the hippocampal formation in the non-epileptic brain hemisphere. We compared EEG synchrony between adjacent recording sites (i) within the entorhinal cortex, (ii) within the hippocampus, and (iii) between the hippocampus and entorhinal cortex. We observed a significant interregional gap in synchrony for the delta and theta band, indicating the existence of independent delta/theta rhythms in different subregions of the human MTL. The interaction of these rhythms could represent the temporal basis for the information processing required for mnemonic encoding and retrieval.

【 授权许可】

Unknown