The theta paradox: 4-8 Hz EEG oscillations reflect both local sleep and cognitive control

Abstract

Human brain activity generates electroencephalographic (EEG) oscillations that characterize specific behavioral and vigilance states. The frequency of these oscillations is typically sufficient to distinguish a given state, however theta oscillations (4-8 Hz) have instead been found in near-opposite conditions of drowsiness during sleep deprivation and alert cognitive control. While the latter has been extensively studied and is often referred to as "frontal midline theta", the former has been investigated far less but is considered to be a marker for local sleep during wake. In this study we investigated to what extent theta oscillations differed during cognitive tasks and sleep deprivation. We measured high-density EEG in 18 young healthy adults performing 6 tasks under 3 levels of sleep deprivation. We found both cognitive load and sleep deprivation increased theta power in medial prefrontal cortical areas, however sleep deprivation caused additional increases in theta in many other, predominantly frontal, areas. The sources of sleep deprivation theta were task-dependent, with a visual-spatial task and short-term memory task showing the most widespread effects. Notably, theta was highest in supplementary motor areas during passive music listening, and highest in the inferior temporal cortex during a spatial game. This suggests that theta caused by sleep deprivation may preferentially occur in cortical areas not involved in ongoing behavior. While our results find differences in topography from frontal midline theta, they raise the possibility that a common mechanism may underly both theta oscillations during cognition and during sleep deprivation.

Sleep-dependent upscaled excitability, saturated neuroplasticity, and modulated cognition in the human brain

“…In humans, where the temporal lobes are located ventrally and thus difficult to record specifically from surface EEG, these theta rhythms with a strong regularity are observed mainly in frontal and midline cortices. The second type of theta, which is of main interest here, is of cortical origin, less regular, predominantly but not exclusively observed over frontal-midline areas and builds up with growing sleep pressure, including sleep deprivation, in both, animals and humans studies ( Finelli et al, 2000 ; Vyazovskiy and Tobler, 2005 ; Brown et al, 2012 ; Magnuson et al, 2022 ; Snipes et al, 2022 ). While there is no clear and direct link between this sleep pressure-dependent theta activity and synaptic strength as suggested by some works, recent works in humans, however, linked it to an increase of cortical excitability ( Kuhn et al, 2016 ).…”

Systematic Review and Meta-Analysis on the Effects of Neurofeedback Training of Theta Activity on Working Memory and Episodic Memory in Healthy Population

“…Each frequency band has distinct cognitive functions. Theta activity (4–7 Hz) accompanies meditation, which is associated with the cortical inhibition of the sensory cortex and deep resting state without falling sleep [ 1 , 2 ]. The theta activity of the frontal midline has a positive correlation with cognition in healthy adults [ 3 , 4 ].…”

Research on brain functions related to visual information processing and body coordination function of pilots based on the low-frequency amplitude method

“…EEG is typically characterized by frequency bands of <4 Hz (deltaδ), 4-7 Hz (thetaθ), 7-13 Hz (alphaα), 13-30 Hz (betaβ), and >30 Hz (gammaγ) (Chen W., 2021). The Delta rhythm is a prominent of deep sleep but is also observed during high cognitive demands and some brain lesions; Theta rhythms can be observed during sleepiness and are often present in the sleep-deprived brain; The Alpha rhythm reflects the relaxed wakefulness with eyes closed; Beta and gamma rhythms are most pronounced during cognitive tasks (Snipes et al, 2022). fMRI utilizes a gradient magnetic field to encode the space, which can directly measure the blood oxygen metabolism of the brain, so the effects of cerebrospinal fluid, skull and scalp could be not considered.…”