Biology subjects

Juventin, M.

Publications and source records attributed to Juventin, M..

3 recordsLinked to original sources

bioRxiv2023

The timing of sleep spindles is modulated by the respiratory cycle in humans

Coupling of sleep spindles with cortical slow waves and hippocampus sharp-waves ripples is crucial for sleep-related memory consolidation. Recent literature evidenced that nasal respiration modulates neural activity in large-scale brain networks. In the rodent, this respiratory drive strongly varies according to vigilance states. Particularly, during sleep, respiration promotes the coupling between hippocampal sharp-wave ripples and cortical DOWN/UP state transitions. However, no study has examined whether sleep spindles could be respiration-modulated in humans. In this work, we aimed to investigate the influence of breathing on brain oscillations during non-rapid-eye-movement stage 2 sleep (N2) in humans by examining the coupling between sleep spindles and respiration cycle. Full night polysomnography of twenty healthy participants were analysed. Spindles and slow waves were detected during N2 sleep stage. Spindle-related sigma power as well as spindle and slow waves events were analysed according to the respiratory phase. We found a significant coupling between slow and fast spindles with respiration cycle, with enhanced sigma activity and probability of occurrence of spindles during the middle part of the expiration phase. A different coupling was observed between breathing and slow waves that were more distributed around both respiration phase transitions. Our findings suggest that breathing cycle influences the dynamics of brain activity during non-rapid-eye-movement sleep. This may enable sleep spindles to synchronize with other brain rhythms including hippocampus sharp wave ripples and facilitate information transfer between distributed brain networks.

neuroscience↗

bioRxiv2020

The deep and slow breathing characterizing rest favors brain respiratory-drive

A respiration-locked activity in the olfactory brain, mainly originating in the mechano-sensitivity of olfactory sensory neurons to air pressure, propagates from the olfactory bulb to the rest of the brain. Interestingly, changes in nasal airflow rate result in reorganization of olfactory bulb response. Therefore, if the respiratory drive of the brain originates in nasal airflow movements, then it should vary with respiration dynamics that occur spontaneously during natural conditions. We took advantage of the spontaneous variations of respiration dynamics during the different waking and sleep states to explore respiratory drive in various brain regions. We analyzed their local field potential activity relative to respiratory signal. We showed that respiration regime was state-specific, and that quiet waking was the only vigilance state during which all the recorded structures can be respiration-driven whatever the respiration frequency. We used a CO2-enriched air to change the respiratory regime associated to each state and, using a respiratory cycle-by-cycle analysis, we evidenced that the large and strong brain entrainment during quiet waking was the consequence of its associated respiration regime consisting in an optimal trade-off between deepness and duration of inspiration. These results show for the first time that changes in respiration regime alter the cortical dynamics and that the respiratory regime associated with rest is optimal for respiration to drive the brain.

neuroscience↗

bioRxiv2018

State-dependent changes in olfactory cortical networks via cholinergic modulation

Activity in sensory cortical networks reflects both peripheral sensory input and intra- and inter-cortical network input. How sensory cortices balance these diverse inputs to provide relatively stable, accurate representations of the external world is not well understood. Furthermore, neuromodulation could alter the balance of these inputs in a state- and behavior-dependent manner. Here, we used optogenetic stimulation to directly assay the relative strength of bottom-up (olfactory bulb) and top-down (lateral entorhinal cortex) synaptic inputs to piriform cortex in freely moving rats. Optotrodes in the piriform cortex were used to test the relative strength of these two inputs, in separate animals, with extracellular, monosynaptic evoked potentials. The results suggest a rapid state-dependent shift in the balance of bottom-up and top-down inputs to PCX, with enhancement in the strength of lateral entorhinal cortex synaptic input and stability or depression of olfactory bulb synaptic input during slow-wave sleep compared to waking. The shift is in part due to a state-dependent change in cholinergic tone as assessed with fiber photometry of GCaMP6 fluorescence in basal forebrain ChAT+ neurons, and blockade of the state-dependent synaptic shift with cholinergic muscarinic receptor activation.

neuroscience↗