Biology subjects

Pellat, S.

Publications and source records attributed to Pellat, S..

3 recordsLinked to original sources

bioRxiv2025

iSleep: Continuous, binocular pupil tracking in sleep and reduced consciousness for physiological monitoring, predictions and interventions

Monitoring pupil dynamics is a key tool in understanding arousal. Pupil size can serve as a biomarker for the autonomic nervous system balance as well as for identifying brain states. While internal states can also be self-reported when awake, automated detection and non-invasive monitoring is crucial during sleep and reduced consciousness. Here, we introduce iSleep, an innovative pupil tracking and analysis framework for sleep in humans. It features comfortable, humidified eye-tracking goggles and a platform for integrated analysis and prediction capabilities. We show that iSleep allows safe and continuous access to binocular pupil size and ocular dynamics during sleep and anesthesia. iSleep reveals that pupillary fluctuations correlate tightly with brain activity, heartbeat, and breathing, and can reliably predict brain states. Pupil constrictions reflect parasympathetic drive and likely serve a protective function for deep sleep stability; while dilations indicate arousals. Unexpectedly, we observed a decoupling of binocular movements during periods of sleep, indicating alterations in reflexes which usually govern voluntary eye movements. Finally, iSleep was tested in surgery patients under general anesthesia, revealing dynamic pupil changes to noxious stimuli, suggesting the potential for nociception monitoring during surgeries. In summary, iSleep offers an easy-to-use, robust alternative to read out brain states during sleep and anesthesia, opening new avenues in monitoring, diagnostics, and treatments, previously obscured by closed eyelids.

neuroscience↗

bioRxiv2025

BlueBerry: Closed-loop wireless optogenetic manipulation in freely moving animals

Optogenetics is a powerful approach for linking neural activity to behavior by enabling precise manipulation of defined neuronal populations. Recent advances in wireless technologies have led to remotely controlled optogenetic devices that facilitate the study of more complex behaviors, including social interactions. However, implementing real-time, automated, closed-loop experiments in large-scale, naturalistic environments and in groups of interacting animals remains challenging. Moreover, many existing devices are difficult to reproduce, requiring specialized engineering expertise or fabrication facilities that are not widely available. Here we introduce BlueBerry (www.OptoBlueBerry.org), a lightweight (1.4 g), battery powered, multi-channel wireless optogenetic device that is openly available for the scientific community and can be assembled entirely from off-the-shelf-components. BlueBerry combines robust long-range wireless communication with flexible control of stimulation parameters, making it particularly suited for behavior-triggered optogenetic experiments in large arenas and in multiple freely interacting animals. We demonstrate that BlueBerry can not only guide decision making during large-scale navigation, but also deliver individually controlled, behavior-triggered optogenetic stimulation to multiple freely interacting mice, enabling modulation of social dynamics in real-time. The open availability, modular design, and straightforward integration with existing behavioral frameworks make BlueBerry a practical and scalable tool for systems neuroscience.

neuroscience↗

bioRxiv2018

Optical alignment device for two-photon microscopy

Two-photon excitation fluorescence microscopy has revolutionized our understanding of brain structure and function through the high resolution and large penetration depth it offers. Investigating neural structures in vivo requires gaining optical access to the brain, which is typically achieved by replacing a part of the skull with one or several layers of cover glass windows. To compensate for the spherical aberrations caused by the presence of these layers of glass, collar-correction objectives are typically used. However, the efficiency of this correction has been shown to depend significantly on the tilt angle between the glass window surface and the optical axis of the imaging system. Here we expand these observations and characterize the effect of the tilt angle on the collected fluorescence signal with thicker windows (double cover glass) and compare these results with an objective devoid of collar-correction. Finally, we present a simple optical alignment device designed to rapidly minimize the tilt angle in vivo and align the optical axis of the microscope perpendicularly to the glass window, thereby significantly improving the imaging quality. The performance of the device is demonstrated in an in vivo setting and a tilt-correction procedure is described, enabling the accurate alignment (<0.2{degrees}) of the cover glass with the imaging plane in only few iterations.

neuroscience↗