Biology subjects

Thevenet, M.

Publications and source records attributed to Thevenet, M..

4 recordsLinked to original sources

bioRxiv2026

Engram and neural underpinning dynamics of the long-lasting childhood olfactory memory

Olfactory childhood memories are particularly important for forming ones identity. However, we dont know how they exert their privileged influence and shape brain structure. To address this, we modeled childhood olfactory memory in mice based on a human survey indicating that our earliest olfactory memory arises from repeated positive experiences paired with a pleasant odorant. Accordingly, mice were exposed during childhood to a pleasant odorant in a playful environment. In adulthood, memory recall relied on neonatal-born granule cells in the olfactory bulb, as their optogenetic silencing impaired retrieval, and on increased functional connectivity in the reward system. With age, memory persistence depended on re-exposure to the childhood odorant and was associated with the disengagement of neonatal-born granule cells, alongside with strengthened limbic functional connectivity. Together, these findings identify neonatal neurons as a key substrate for encoding childhood olfactory memory and reveal dynamic reorganization of brain networks supporting its long-term significance.

neuroscience↗

bioRxiv2024

Enhancing Statistical Power While Maintaining Small Sample Sizes in Behavioral Neuroscience Experiments Evaluating Success Rates

Studies with low statistical power reduce the probability of detecting true effects and often lead to overestimated effect sizes, undermining the reproducibility of scientific results. While several free statistical software tools are available for calculating statistical power, they often do not account for the specialized aspects of experimental designs in behavioral studies that evaluate success rates. To address this gap, we developed "SuccessRatePower" a free and user-friendly power calculator based on Monte Carlo simulations that takes into account the particular parameters of these experimental designs. Using "SuccessRatePower", we demonstrated that statistical power can be increased by modifying the experimental protocol in three ways: 1) reducing the probability of succeeding by chance (chance level), 2) increasing the number of trials used to calculate subject success rates, and, in some circumstance, 3) employing statistical analyses suited for discrete values. These adjustments enable even studies with small sample sizes to achieve high statistical power. Finally, we performed an associative behavioral task in mice, confirming the simulated statistical advantages of reducing chance levels and increasing the number of trials in such studies

neuroscience↗

bioRxiv2023

Long-Run Olfactory Enrichment Promotes Non-Olfactory Cognition, Noradrenergic Plasticity And Remodeling Of Brain Functional Connectivity In Aged Mice

Normal brain aging is accompanied by functional and structural changes, leading to cognitive decline. A high level of cognitive stimulation during life is associated with improved cognitive performances in elderly, forming the so-called cognitive reserve whose cellular mechanisms remain largely unknown. Noradrenaline has been proposed as a molecular link between environmental stimulation and the constitution of the cognitive reserve. Taking advantage of the ability of olfactory stimulation to trigger noradrenaline release, we used repeated olfactory enrichment sessions distributed over the mouse lifespan to enable the cognitive reserve buildup. Mice submitted to lifelong olfactory enrichment whether started in early or late adulthood, displayed improved olfactory discrimination at late ages. Interestingly, benefits extended to spatial memory and cognitive flexibility and olfactory and non-olfactory cognitive performances correlated with increased noradrenergic innervation in the olfactory bulb and dorsal hippocampus. Finally, using c-Fos mapping and connectivity analysis, we reported task-specific remodeling of functional neural networks in aged mice with increased network specialization or enlargement in an olfactory discrimination or a spatial memory task respectively. We thus propose long-run olfactory enrichment as a mouse model of the cognitive reserve buildup relying on plasticity of the noradrenergic system and network remodeling to promote better cognitive aging.

neuroscience↗

bioRxiv2022

Distinct brain networks for remote episodic memory depending on content and emotional value

The mechanisms that underlie the storage of old nontraumatic episodic memories remain enigmatic because of the difficulty in modelling this particular type of memory in humans and animals. Episodic memories combine incidental and occasional "What-Where-When/In which context" multisensory information and can be stored for long periods of time. Here, using a task in rodents that models human episodic memory, including odour/place/context components, we applied advanced behavioural and computational analyses and brain imaging of c-Fos and Zif268 to characterize remote episodic memories and their engrams for the first time. We show that the content and accuracy of memories vary across individuals and depend on the emotional relationship with odours experienced during episodes. Activated brain networks reflect the nature and content of remote episodic memories and their transformation over time, and emotional cortico-hippocampal networks play critical roles in maintaining vivid memories.

neuroscience↗