Dipole source analysis of temporal slow waves in the elderly.
BACKGROUND
Temporal low-voltage irregular delta-waves (TLID) are often found in elderly subjects. The physiological significance of TLID has not been clarified; however, our previous studies suggest that TLID are associated with mild cerebrovascular dysfunction.


OBJECTIVE
The present study aimed to reveal the origin of TLID and their neural mechanisms by dipole source modeling.


METHODS
From electroencephalography records taken from 21 scalp electrodes, clear and typical TLID of 6 elderly subjects (mean age, 69 +/- 6.2 years) were selected. Among these, we selected and averaged 7-12 clear TLID on the left side in each subject, and estimated a single equivalent current dipole for the averaged TLID.


RESULTS
The best equivalent current dipoles were estimated to be located in the medial part of the temporal lobe in or near the parahippocampal gyrus in the hemisphere ipsilateral to the TLID, with a high reliability in all subjects.


CONCLUSIONS
Considering the source localization of TLID, TLID seem to indicate certain dysfunctions of the hippocampus or adjacent regions. This is the first study to report the cerebral origin of TLID and suggest its physiological significance.
Motomura
Eishi
E
Department of Psychiatry, Division of Neuroscience, Institute of Medical Science, Mie University Graduate School of Medicine, Tsu, Japan. motomura@clin.medic.mie-u.ac.jp
Inui
Koji
K
Ogawa
Hiroyuki
H
Nakase
Shinji
S
Hamanaka
Kenji
K
Honda
Tomoyuki
T
Shiroyama
Takashi
T
Matsumoto
Takuya
T
Komori
Teruhisa
T
Okada
Motohiro
M
Kakigi
Ryusuke
R
D000368:Aged; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000503:physiopathology*; D002544:Cerebral Infarction / Q000175:diagnosis / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D004567:Electrodes, Implanted; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D013702:Temporal Lobe / Q000503:physiopathology*; D013997:Time Factors