Neural responses to acute hypoxia and hyperoxia.

Area of Science:

• Neuroscience
• Cognitive Science
• Physiology

Background:

• The brain's high metabolic rate makes it sensitive to oxygen fluctuations.
• Understanding the neural mechanisms of hypoxia and hyperoxia on brain function is crucial.

Purpose of the Study:

• To investigate the effects of acute normobaric hypoxia and hyperoxia on neural function and perceptual thresholds.
• To characterize the impact of varying oxygen levels on electroencephalography (EEG), visual evoked potentials (VEPs), and critical flicker fusion (CFF) thresholds.

Main Methods:

• A single-blind, randomized, crossover study involving 30 participants.
• Participants inhaled different oxygen concentrations (10.5%, 21%, 100%) while undergoing EEG, VEP, and CFF measurements.
• Analysis of resting-state EEG power spectra, VEP components, and CFF thresholds.

Main Results:

• Hypoxia dose-dependently reduced CFF thresholds and increased delta, theta, and beta EEG power, alongside increased spectral entropy, indicating impaired synchrony.
• Hyperoxia caused transient CFF reduction, altered EEG power across multiple bands (theta, alpha, beta, gamma), and increased fuzzy entropy, suggesting altered neural complexity.
• VEPs showed hypoxia-induced reductions in P1 amplitude and increased N2 deflections, while hyperoxia transiently increased P1 amplitude, indicating disrupted sensory processing.

Conclusions:

• Altered cerebral oxygen levels significantly impact fundamental neural processing and brain function in state- and time-dependent ways.
• EEG and CFF serve as valuable biomarkers for monitoring neural responses to oxygen variability.
• Findings provide insights into oxygen-induced neuromodulation mechanisms.