Brain Connectivity and Corticospinal Excitability in Response to Moderate Hypoxia

NCT07516028 | Recruiting

• 1 other identifier: 2025-A02509-40
• Study Type: interventional
• Target: 36
• Locations: 1 country
• Sites: 1

Brief Summary

Hypoxia, defined as a reduction in the availability of oxygen, induces significant physiological adaptations. While the deleterious effects of severe and chronic hypoxia are well documented, several studies indicate that moderate hypoxia - particularly when administered intermittently - may produce beneficial effects on cardiometabolic health (e.g., improved regulation of blood pressure and better glycaemic control). However, its impact on the dynamics of brain circuits in humans remains relatively underexplored. The present project aims to characterise the effects of continuous and intermittent moderate hypoxia on resting-state brain dynamics in healthy adults. To this end, simultaneous electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) recordings will be conducted in order to extract functional and haemodynamic markers of brain activity. This project will contribute to a better understanding of the neurophysiological mechanisms associated with hypoxic conditioning and to the assessment of its potential application in innovative therapeutic approaches.

Conditions

Normoxia; Intermittent Moderate Hypoxia; Continuous Moderate Hypoxia

Keywords

hypoxia; eeg; fnirs; motor-evoked potentials; tms

Outcome Measures

Primary Outcomes (2)

• Electrical brain activity

  Electroencephalography (EEG) data will be recorded using a SAGA system (TMSi, Einsteinweg, The Netherlands). This system includes 64 Ag/AgCl pin-type electrodes. An additional electrode will be positioned on either the left or right mastoid. The primary outcome will be the variation in spectral power within the alpha frequency band.

  Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.

• Haemodynamic activity

  A Brite system (Artinis, Einsteinweg, The Netherlands) will be used to collect functional near-infrared spectroscopy (fNIRS) data. The equipment comprises four LED emitters and four photodiode receivers. A nine-channel montage will be designed to cover the regions of interest, namely the dorsolateral prefrontal cortex, the ventromedial prefrontal cortex, and the anterior prefrontal cortex. The primary outcome will be the variation in deoxyhaemoglobin (HbR).

  Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.

Secondary Outcomes (3)

• Corticospinal excitability

  Assessed at baseline and immediately post-intervention during each of the three experimental sessions (i.e., intermittent moderate hypoxia, continuous moderate hypoxia, normoxia).

• EEG brain connectivity

  Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.

• fNIRS brain connectivity

  Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.

Study Arms (3)

Normoxia

SHAM COMPARATOR

The sham condition will consist of 30 minutes of continuous exposure to ambient air, inhaled through the same mask as that used during the hypoxia conditions.

Device: Normoxia; Device: Transcranial Magnetic Stimulation

Continuous moderate hypoxia

EXPERIMENTAL

The duration of exposure to continuous hypoxia will be 30 minutes. A peripheral oxygen saturation (SpO₂) between 85% and 90% will be targeted. Hypoxic exposure will take place at rest, with the participant comfortably seated. In addition, the hypoxic device used in the study is equipped with a safety system allowing a minimum fraction of inspired oxygen (FiO₂) to be defined. This threshold will be set at 10%, ensuring that the FiO₂ cannot fall below this value.

Device: Moderate hypoxia; Device: Transcranial Magnetic Stimulation

Intermittent moderate hypoxia

EXPERIMENTAL

The intermittent hypoxia condition will consist of six periods of 5 minutes of hypoxia interspersed with 5-minute periods of normoxia. During the hypoxic periods, a SpO₂ between 85% and 90% will be targeted. As in the continuous condition, hypoxic exposure will take place at rest, with the participant comfortably seated. The hypoxic device also includes a safety system allowing a minimum FiO₂ to be defined; this threshold will be set at 10%, ensuring that the FiO₂ cannot fall below this value.

Device: Moderate hypoxia; Device: Transcranial Magnetic Stimulation

Interventions

Moderate hypoxia DEVICE

Altitude conditions (normobaric hypoxia) will be reproduced using the OnePlus VA device (GO2Altitude, Biomedtech, Melbourne, Australia). This device modulates the fraction of inspired oxygen (FiO₂) through a patented semi-permeable membrane system developed by the company. It thereby produces a gas mixture that is inhaled by the participant through a mask. This device included an oxygen-reduction algorithm, that adjusts the FiO₂ in real time according to a target peripheral oxygen saturation (SpO₂ = 85-90%).

Continuous moderate hypoxia; Intermittent moderate hypoxia

Normoxia DEVICE

Ambient air will be delivered through the same mask as that used during the hypoxia conditions.

Normoxia

Transcranial Magnetic Stimulation DEVICE

Single- and paired-pulse TMS will be applied over the primary motor cortex (M1) to assess corticospinal excitability, along with intracortical inhibitory and facilitatory mechanisms. Motor-evoked potentials will be recorded from the abductor pollicis brevis (APB) muscle of the dominant hand.

Also known as: TMS

Continuous moderate hypoxia; Intermittent moderate hypoxia; Normoxia

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Male or female aged 18 to 65 years
• Healthy right- or left-handed individuals with no self-reported neurological disorders or history of neurological conditions (e.g., epilepsy, stroke, brain or spinal surgery, or neurological diseases affecting motor or sensory function such as multiple sclerosis, or neurodegenerative diseases such as Parkinson's or Alzheimer's)
• Individuals who have provided informed consent and have sufficient proficiency in French
• Participants affiliated with, or beneficiaries of, a social security scheme

You may not qualify if:

• Body mass index (BMI) greater than 30 kg/m²
• Diagnosed and untreated obstructive sleep apnoea syndrome
• Inability to provide informed consent
• History of cardiac (e.g., ischaemic heart disease, heart failure) and/or respiratory disorders (e.g., COPD, chronic respiratory insufficiency, persistent or uncontrolled asthma)
• Current smokers
• Contraindications to TMS (e.g., uncontrolled epilepsy, intracranial metallic foreign body, hearing aid or cochlear implant, implanted stimulator or pump, scalp lesions, elevated intracranial pressure, cerebrospinal fluid shunt)
• Use of psychotropic medication
• Individuals under legal guardianship or curatorship
• Pregnant or breastfeeding women

Sponsors & Collaborators

• Universite du Littoral Cote d'Opale: lead

Study Sites (1)

Eurasport

Loos, Hauts-de-France, 59120, France

RECRUITING

MeSH Terms

Conditions

Hypoxia

Interventions

Transcranial Magnetic Stimulation

Condition Hierarchy (Ancestors)

Signs and Symptoms, Respiratory; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Magnetic Field Therapy; Therapeutics

Central Study Contacts

Ségolène M. R. Guérin, PhD

CONTACT

+33 3 74 00 82 13; segolene.guerin@univ-littoral.fr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 5, 2026
• First Posted: April 7, 2026
• Study Start: March 15, 2026
• Primary Completion (Estimated): December 20, 2026
• Study Completion (Estimated): December 20, 2026
• Last Updated: September 21, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

FR (1)