Biology subjects

Charpier, S.

Publications and source records attributed to Charpier, S..

3 recordsLinked to original sources

bioRxiv2026

Brain-heart interactions predict brain activity recovery after systemic anoxia

Global cerebral anoxia is a leading cause of death and resuscitated patients often remain persistently affected by neurological deficits. While previous studies suggest that brain-heart electrophysiological interactions may predict severity and prognosis after hypoxic brain injury coma, little is known about the brain-heart dynamics at near-death. Gaining insight into these mechanisms is crucial for developing targeted interventions in critical conditions. Using a rodent model of reversible systemic anoxia (n=29, male and female rats), we investigated whether brain-heart interactions during the asphyxia onset could predict the return of brain electrical activities after resuscitation. Electrophysiological recordings confirmed that cerebral activity declines following asphyxia, coinciding with increased heart rate variability. Notably, the strong coupling between cardiac parasympathetic activity and high-frequency brain activity in the somatosensory cortex and hippocampus serves as a key predictor of a survival. Our study underscores the potential involvement of the brain-heart axis in the physiology of dying and the potential prognostic significance of the underlying mechanisms, paving the way for translational research into critical care, based on new characterizations of cardiac reflexes and brain-heart interactions. Significance StatementUnderstanding the physiological processes that determine survival and recovery following systemic anoxia is critical for improving outcomes in critical care. This study reveals that brain-heart dynamics during the onset of systemic anoxia relate to survival after resuscitation. In particular, the coupling between parasympathetic cardiac activity and high-frequency brain signals. Using a reversible anoxia rodent model, we demonstrate that early brain-heart interactions are not merely consequences of anoxia, but active markers of resilience. These findings offer a novel framework for understanding the physiology of dying and to ultimately developing prognostic tools based on real-time physiological monitoring.

neuroscience↗

bioRxiv2025

Oscillatory impact of Transcranial Magnetic Stimulation at very weak-intensity on the primary motor cortex: A TMS-EEG study in the human brain

Transcranial Magnetic Stimulation is widely used to probe and modulate human brain function, yet the neural effects of stimulation delivered at very low intensities remain unclear. Here, we show that very low intensity magnetic pulses can alter ongoing oscillatory activity in the human primary motor cortex. In healthy participants, we combined transcranial magnetic stimulation with electroencephalography to assess neural responses to single pulses and rhythmic stimulation in the motor cortex. Conventional high intensity stimulation produced robust evoked responses and synchronized beta-frequency oscillations. Low-intensity rhythmic stimulation, despite generating much weaker direct responses, modified local oscillatory activity in a manner consistent with phase-dependent enhancement of ongoing rhythms. These findings suggest that cortical oscillations can be influenced by magnetic fields substantially weaker than those typically used in human studies. Low-intensity stimulation may therefore offer a route towards portable, energy-efficient technologies for investigating and modulating brain networks.

neuroscience↗

bioRxiv2022

In vivo low-intensity magnetic pulses durably alter neocortical neuron excitability and spontaneous activity.

Magnetic brain stimulation is a promising treatment for neurological and psychiatric disorders. However, a better understanding of its effects at the individual neuron level is essential to improve its clinical application. We combined focal low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) to the rat somatosensory cortex with intracellular recordings of subjacent pyramidal neurons in vivo. Continuous 10 Hz LI-rTMS reliably evoked firing at [~]4-5 Hz during the stimulation period and induced durable attenuation of synaptic activity and spontaneous firing in cortical neurons, through membrane hyperpolarization and a reduced intrinsic excitability. However, inducing firing in individual neurons by repeated intracellular current injection did not reproduce LI-rTMS effects on neuronal properties. These data provide novel understanding of mechanisms underlying magnetic brain stimulation showing that, in addition to inducing biochemical plasticity, even weak magnetic fields can activate neurons and enduringly modulate their excitability.

neuroscience↗