title: Human neocortical and hippocampal near-DC shifts are interconnected.
abstract: Hippocampal DC shifts have been observed under various physiological and pathological conditions. Here, we studied the interconnection of slow shifts (0.01 Hz high-pass) in surface EEG and hippocampal shifts as emerging in an event-related EEG biofeedback paradigm. Hippocampal EEG activity was monitored by depth electrodes implanted in four epilepsy patients for presurgical evaluation. Trials were sorted according to the near-DC shifts occurring at the surface position Cz, which was the feedback electrode, into positive, indistinct (i.e., small or biphasic) and negative shifts. We found significant hippocampal near-DC shifts being positively or negatively correlated to the shifts in surface EEG in all four patients. The amplitudes of the hippocampal near-DC shifts were several times larger than the surface shifts. The polarity of the shifts appears to depend on the location of the electrode contacts with respect to the hippocampal subfields. The finding that neocortical and hippocampal near-DC shifts are interconnected may open new perspectives for the prediction and control of mediotemporal lobe seizures.
authors: Department of Epileptology, University of Bonn, D-53105 Bonn, Germany. juergen.fell@ukb.uni-bonn.de
authors: Juergen
authors: J
authors: Fell
authors: Navah E
authors: NE
authors: Fritz
authors: Wieland
authors: W
authors: Burr
authors: Eva
authors: E
authors: Ludowig
authors: Nikolai
authors: N
authors: Axmacher
authors: Christian E
authors: CE
authors: Elger
authors: Christoph
authors: C
authors: Helmstaedter
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001676:Biofeedback, Psychology; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology; D007839:Functional Laterality / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019579:Neocortex / Q000503:physiopathology*; D010775:Photic Stimulation