The interplay of lorazepam-induced brain oscillations: microstructural electromagnetic study.
OBJECTIVE
The effects on cortical rhythms of a single-dose (30 microg/kg) administration of the GABAA agonist lorazepam were examined in a randomized, double-blind, cross-over, placebo-controlled study with 8 healthy volunteers using simultaneous electroencephalography (EEG) and magnetoencephalography (MEG).


METHODS
The oscillations were assessed by means of adaptive classification of short-term spectral patterns.


RESULTS
Lorazepam (a) decreased the percentage of EEG/MEG segments with fast-theta, delta-alpha, fast-theta-alpha and alpha activity and increased percentage of EEG/MEG segments with delta, delta-slow-theta, delta-beta, slow-theta and polyrhythmic activity; (b) decreased diversity of EEG/MEG signals (in terms of spectral patterns) and increased the general instability of the signal; (c) increased stabilization periods of the spectral patterns (reduced brain information processing); (d) maintained larger maximum periods of temporal stabilization for delta, slow-theta, delta-slow-theta, delta-beta and polyrhythmic activity (in terms of spectral patterns); (e) did not increase power in the independent beta rhythm.


CONCLUSIONS
Lorazepam caused significant reorganization of the EEG/MEG microstructure. These results suggest also that adaptive classification analysis of single short-term spectral patterns may provide additional information to conventional spectral analyses.
Fingelkurts
Alexander A
AA
BM-Science Brain & Mind Technologies Research Centre, Espoo, Finland. alexander.fingelkurts@bm-science.com
Fingelkurts
Andrew A
AA
Kivisaari
Reetta
R
Pekkonen
Eero
E
Ilmoniemi
Risto J
RJ
Kähkönen
Seppo
S
D000328:Adult; D001611:Beta Rhythm; D001921:Brain / Q000187:drug effects* / Q000502:physiology*; D018592:Cross-Over Studies; D003700:Delta Rhythm; D004311:Double-Blind Method; D004569:Electroencephalography; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology*; D006801:Humans; D008140:Lorazepam / Q000494:pharmacology*; D015225:Magnetoencephalography; D008297:Male; D012016:Reference Values; D013826:Theta Rhythm
D018755:GABA Agonists; D008140:Lorazepam