Steinwurzel, C. | Search bioRxiv

bioRxiv2025

Acute supplementation of beta-hydroxybutyrate increases visual cortical excitability in humans: a combined EEG and MRS study

Increasing plasma levels of ketone bodies via supplementation or dieting has been repeatedly used to ameliorate neurological symptoms and enhance cognitive performance. Here we aim to gain insight into the underlying mechanisms by characterizing the acute effects on visual cortical function of a single dose {beta}-hydroxybutyrate ({beta}HB) supplementation. Young human volunteers were orally administered a {beta}HB ester; we used EEG to assess cortical excitability and responsivity to visual stimulation, and Magnetic Resonance Spectroscopy to quantify glutamate and GABA+ concentrations in the occipital cortex. {beta}HB supplementation increased the amplitude of Visual Evoked Potentials and enhanced the resting-state EEG alpha rhythm. These electrophysiological changes were paralleled by a neurometabolic change in the occipital cortex, where glutamate (but not GABA+) concentration increased. The glutamate increase was correlated with the increased Visual Evoked Potential amplitude. This suggests that acute {beta}HB supplementation increases the excitability of the brain cortex, as assessed neurometabolically and electrophysiologically.

neuroscience↗

bioRxiv2025

Short-term monocular deprivation in adult humans: a meta-analysis and new perspectives

Starting from the early 2010s [1, 2], several studies have shown that a short period of monocular deprivation in adult volunteers transiently shifts ocular dominance in favor of the deprived eye. We compiled a meta-analysis of 73 such studies that measured the effects of monocular deprivation and related manipulations, using a diverse set of techniques [1-73]. The ocular dominance shift elicited by monocular deprivation was comparable across studies where deprivation was achieved with an opaque or translucent patch and irrespectively of whether the dominant or non-dominant eye was deprived. Effects were larger and longer lasting after longer periods of deprivation. Qualitatively similar effects were produced by monocular manipulations that did not reduce the strength of the stimulus: filtering or distorting the image in one eye, suppressing it from awareness or merely making it task irrelevant. We discuss the available evidence in the light of current models and a new perspective inspired by predictive coding.

neuroscience↗