Brain Research 913 (2001) 220–223 www.bres-interactive.com Interactive report Unihemispheric enhancement of delta power in human frontal sleep q EEG by prolonged wakefulness * ´ Peter Achermann , Luca A. Finelli, Alexander A. Borbely ¨ ¨ Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland Accepted 12 July 2001 Abstract EEG power spectra exhibit site-specific and state-related differences in specific frequency bands. In the present study we investigated the effect of total sleep deprivation on sleep EEG topography. Eight healthy, young, right-handed subjects were recorded during baseline sleep and recovery sleep after sleep deprivation. Forty hours of sleep deprivation affected power spectra in all derivations. However, hemispheric asymmetries were observed in the delta range. Sleep deprivation enhanced the anterior predominance of delta activity in the left hemisphere but not in the right one. This effect may reflect a functional asymmetry between the dominant and non-dominant hemisphere. The results provide further evidence for the presence of both global and local aspects of sleep regulation.  2001 Elsevier Science B.V. All rights reserved. Theme: Neural basis of behavior Topic: Biological rhythms and sleep Keywords: Spectral analysis; EEG topography; Hemispheric asymmetry; NonREM sleep The analysis of regional changes in EEG power spectra were included. The findings on the waking EEG have been of baseline sleep demonstrated that the antero-posterior reported previously [4]. gradients are not homogenous but exhibit site-specific and Eight right-handed, healthy male volunteers (mean age state-related changes in different frequency bands 23 years60.46 S.E.M., range 21–25 years) participated in [9,10,13,14]. In the first nonREM (NREM) sleep episode, the study. Prior to being selected for the study they power in the 2-Hz band was highest in the anterior underwent a screening night in the sleep laboratory. derivation; over the subsequent episodes, the anterior Exclusion criteria were the presence of sleep disturbances preponderance of power declined and eventually vanished such as sleep apnoea and nocturnal myoclonus, prolonged [13,14]. After partial deprivation of NREM sleep by sleep latency and low sleep efficiency. After a baseline frequent awakenings for 3 consecutive nights [15] or after night (23:00 to 07:00 h), preceded by an adaptation night, total sleep deprivation (TSD) for 40 h [3], delta power subjects were kept awake for 40 h. Subsequent recovery during subsequent sleep was most enhanced in the frontal sleep started at 23:00 h. Subjects were allowed to sleep till areas. These results support the notion of a specific 11:00 h. During the sleep deprivation period subjects involvement of the frontal cortex in the sleep process (for remained in the sleep laboratory and surrounding area review see Ref. [6]). In the present study we further under constant surveillance by a member of the experimen- investigated the effect of TSD on EEG topography, and tal team. They spent the time reading, studying, watching examined in particular whether hemispheric asymmetries movies, playing computer games, or taking short walks outside. The study protocol was approved by the local ethics committee. The EEG, EOG and submental EMG were recorded by a polygraphic amplifier (EASYS2, q Published on the World Wide Web on 9 August 2001. Neuroscience Technology Research Ltd., Prague, Czech *Corresponding author. Tel.: 141-1-635-5954; fax: 141-1-635-5707. Republic; sampling rate 128 Hz; low-pass filter at 30 Hz). E-mail addresses: acherman@pharma.unizh.ch (P. Achermann), http:/ / www.unizh.ch / phar / sleep / (P. Achermann). The EEG was recorded with a montage of 27 scalp 0006-8993 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0006-8993(01)02796-2 History: 1. 21 Dec 2016: Print hardcopy