Biology subjects

de Lavilleon, G.

Publications and source records attributed to de Lavilleon, G..

4 recordsLinked to original sources

bioRxiv2022

Distinction between slow waves and delta waves sheds light to sleep homeostasis and their association to hippocampal sharp waves ripples

Cortical slow waves and delta waves are hallmarks of NREM sleep and key elements in physiological processes such as memory consolidation and sleep homeostasis. However, no clear distinction has been made between the two types of electrophysiological events. We introduce a new distinction between slow waves, large amplitude waves on filtered LFP cortical signals, and delta waves, characterized by an inversion between deep and superficial layers and the co-occurrence with a cortical down state. Detection of slow waves, as large amplitude waves during NREM sleep, reveals that a large portion of them does not share the properties of delta waves and does not co-occur with cortical down states. Therefore, we distinguish type-1 slow waves, that are associated to a down state, from type-2 slow waves. We show that 1) only type-1 slow waves undergo strong homeostatic regulations and 2) type-2 slow waves create confusion about the temporal link with hippocampal sharp-wave ripples. Thus, we confirm that delta waves detected with our new method can be used as a proxy for down state. Altogether, this confirms the importance of a robust and accurate definition of delta waves to understand the fine neurophysiological mechanisms at stake during NREM sleep.

neuroscience↗

bioRxiv2018

Improved sleep scoring in mice reveals human-like stages.

Rodents are the main animal model to study sleep. Yet, in spite of a large consensus on the distinction between rapid-eye-movements sleep (REM) and non-REM sleep (NREM) in both humans and rodent, there is still no equivalent in mice of the NREM subdivision classically described in humans.\n\nHere we propose a classification of sleep stages in mice, inspired by human sleep scoring. By using chronic recordings in medial prefrontal cortex (mPFC) and hippocampus we can classify three NREM stages with a stage N1 devoid of any low oscillatory activity and N3 with a high density of delta waves. These stages displayed the same evolution observed in human during the whole sleep or within sleep cycles. Importantly, as in human, N1 in mice is the first stage observed at sleep onset and is increased after sleep fragmentation in Orexin-/- mice, a mouse model of narcolepsy.\n\nWe also show that these substages are associated to massive modification of neuronal activity. Moreover, considering these stages allows to predict mPFC neurons evolution of firing rates across sleep period. Notably, neurons preferentially active within N3 decreased their activity over sleep while the opposite is seen for those preferentially active in N1 and N2.\n\nOverall this new approach shows the feasibility of NREM sleep sub-classification in rodents, and, in regard to the similarity between sleep in both species, will pave the way for further studies in sleep pathologies given the perturbation of specific sleep substages in human pathologies such as insomnia, somnambulism, night terrors, or fibromyalgia.

neuroscience↗

bioRxiv2018

Dissociation of fear initiation and maintenance by breathing-driven prefrontal oscillations

Does the body play an active role in emotions? Since the original James/Cannon controversy this debate has mainly been fueled by introspective accounts of human experience. Here, we use the animal model to demonstrate a physiological mechanism for bodily feedback and its causal role in the stabilization of emotional states. We report that during fear-related freezing mice breathe at 4Hz and show, using probabilistic modelling, that optogenetic perturbation of this feedback specifically reduces freezing maintenance without impacting its initiation. This rhythm is transmitted by the olfactory bulb to the prefrontal cortex where it organizes neural firing and optogenetic probing of the circuit demonstrates frequency-specific tuning that maximizes prefrontal cortex responsivity at 4Hz, the breathing frequency during freezing. These results point to a brain-body-brain loop in which the initiation of emotional behavior engenders somatic changes which then feedback to the cortex to directly participate in sustaining emotional states.

neuroscience↗

bioRxiv2017

Harnessing sleep/wake state tracking by olfactory bulb oscillations to perform fully brain-based sleep scoring in mice

It has long been thought that sleep scoring could not be achieved with brain signals alone despite the deep neuromodulatory transformations that accompany sleep state changes. Here we demonstrate using multi-site electrophysiological LFP recordings in freely moving mice that gamma power in the olfactory bulb (OB) allows for clear classification of sleep and wake. Coupled with hippocampal theta activity, it allows the construction of a sleep scoring algorithm that relies on brain activity alone. This method reaches over 90% homology with classical methods based on muscular activity (EMG) and video tracking. Moreover, contrary to EMG, OB gamma power allows correct discrimination between sleep and immobility in ambiguous situations such as fear-related freezing. We use the instantaneous power of hippocampal theta oscillation and OB gamma oscillation to construct a 2D phase-space that is highly robust across mice and days. Dynamic analysis of trajectories within this space yields a novel characterization of sleep/wake and wake/sleep transitions as deeply divergent phenomena. Whereas waking up is a fast and direct transition, falling asleep is best described as stochastic and gradual change. Altogether this methodology opens the avenue for multi-timescale characterization of sleep states with high temporal resolution based on brain signals only.

neuroscience↗