Principal component analysis of electroencephalographic activity during sleep and wakefulness in the spider monkey (Ateles geoffroyi)

Abstract

The study of electroencephalographic (EEG) activity during sleep in the spider monkey has provided new insights into primitive arboreal sleep physiology and behavior in anthropoids. Nevertheless, studies conducted to date have maintained the frequency ranges of the EEG bands commonly used with humans. The aim of the present work was to determine the EEG broad bands that characterize sleep and wakefulness in the spider monkey using principal component analysis (PCA). The EEG activity was recorded from the occipital, central, and frontal EEG derivations of six young‐adult male spider monkeys housed in a laboratory setting. To determine which frequencies covaried and which were orthogonally independent during sleep and wakefulness, the power EEG spectra and interhemispheric and intrahemispheric EEG correlations from 1 to 30 Hz were subjected to PCA. Findings show that the EEG bands detection differed from those reported previously in both spider monkeys and humans, and that the 1–3 and 2–13 Hz frequency ranges concur with the oscillatory activity elucidated by cellular recordings of subcortical regions. Results show that applying PCA to the EEG spectrum during sleep and wakefulness in the spider monkey led to the identification of frequencies that covaried with, and were orthogonally independent of, other frequencies in each behavioral vigilance state. The new EEG bands differ from those used previously with both spider monkeys and humans. The 1–3 and 2–13 Hz frequency ranges are in accordance with the oscillatory activity elucidated by cellular recordings of subcortical regions in other mammals.

Topographic distribution of the EEG ad hoc broad bands during sleep and wakefulness in the spider monkey (Ateles Geoffroyi)

“…In light of earlier EEG analyses of this species (Cruz‐Aguilar et al, 2020; Cruz‐Aguilar et al, 2018b), and previous topographic EEG sleep studies (Tanaka et al, 2000; Werth et al, 1996; Zeitlhofer et al, 1993), we provide the following hypotheses: (1) During wakefulness, the spatial distribution of the 11–30 Hz band will be nonspecific throughout the cerebral cortex, but the 1–3 Hz and 3–12 Hz bands will predominate in posterior regions. (2) For N1 sleep, the 2–13 Hz band will predominate in central regions of the cerebral cortex, while the 13–30 Hz band will be present mainly in anterior and posterior areas.…”

“…Previous studies have used PCA to evaluate EEG activity during sleep in humans (Corsi‐Cabrera et al, 2000; Donskaya et al 2012; Putilov & Donskaya, 2016; Putilov, 2015a; 2015b), and rodents (Corsi‐Cabrera et al, 2001). Cruz‐Aguilar et al (2020) used PCA to determine the typical EEG bands that characterize sleep and wakefulness in the spider monkey and the direction of changes in EEG spectral power in frequency ranges associated with different sleep stages. In that study, interhemispheric and intrahemispheric EEG correlations, as well as the power EEG spectra from 1 to 30 Hz, were subjected to PCA to identify certain frequencies that covaried with others during wakefulness and the various sleep stages.…”

“…PCA analysis on its own does not allow the precise identification of the cortical areas in which different EEG bands are generated. Cruz‐Aguilar et al (2020) submitted the EEG from all derivations in conjunction to PCA analysis, but their results did not accurately show the cortical regions where EEG bands predominated in the spider monkey. Identifying those regions is important because previous studies suggest that EEG bands related to arboreal body postures (Cruz‐Aguilar et al, 2018a) and the regulation of arousal in this species during sleep (Cruz‐Aguilar et al, 2018b) exist in specific cortical regions.…”

“…However, the specific spatio‐temporal distribution of the EEG bands in the spider monkey has not been analyzed. Thus, considering that topographic EEG mapping may represent local functions of the brain (Cook et al, 1998), we were interested in characterizing the topographic distribution of EEG spectral power of the new specific broad bands obtained previously by PCA analysis in spider monkeys (Cruz‐Aguilar et al,2020) in relation to behavioral stages.…”

“…In light of earlier EEG analyses of this species (Cruz-Aguilar et al, 2020;Cruz-Aguilar et al, 2018b), and previous topographic EEG sleep studies (Tanaka et al, 2000;Werth et al, 1996;Zeitlhofer et al, 1993), we provide the following hypotheses: (1) During wakefulness, the spatial distribution of the 11-30 Hz band will be nonspecific throughout the cerebral cortex, but the 1-3 Hz and…”