Biology subjects

Morvan, T.

Publications and source records attributed to Morvan, T..

4 recordsLinked to original sources

bioRxiv2025

Lateralized foraging induces asymmetric corticostriatal plasticity in mice

With practice, animals perform reward-oriented actions faster and with less variability. The dorsal striatum (DS) plays a key role in this process, potentially through opposing changes in cortical input strength to the two main striatal projection neurons (D1- and D2-SPNs). To test this hypothesis, we trained mice in a foraging task requiring them to perform quarter-turns (QTs) in a single direction (counterclockwise, CCW) along the walls of square towers to collect drops of water. As training progressed, the number and speed of CCW QTs increased while the variability of their trajectory decreased. Whisker trimming in well-trained mice altered QTs kinematics, highlighting the role of tactile inputs in guiding these actions. Combining ex vivo patch-clamp recordings in the DS with glutamate uncaging in the barrel cortex, we mapped the cortical neurons monosynaptically connected to D1- or D2-SPNs and measured the strength of these connections in the contralateral hemispheres, relative to the turn direction. In well-trained mice, compared to naive controls, the contralateral hemisphere showed no major changes in D1- or D2-SPNs connectivity, despite increased excitation of cortical pyramidal neurons. In contrast, the ipsiversive hemisphere exhibited no change in cortical excitability but showed increased cortical connectivity and input strength to SPNs. These findings reveal an unexpected hemispheric asymmetry in corticostriatal connectivity during lateralized foraging, which may reflect a homeostatic process normalizing striatal activity across hemispheres despite unbalanced cortical input.

neuroscience↗

bioRxiv2025

Healthy soils, rising pests? Stopping plowing improves soil quality but increases wireworm infestation: evidence from a long-term field study

Conventional tillage (i.e. plowing) is often associated with soil degradation and a loss of biodiversity. In response, reduced tillage has increasingly been promoted as a sustainable alternative for its positive impacts on soil structure, water dynamics, and biodiversity. However, reduced tillage not only favors beneficial soil-dwelling organisms, but also pests. In this field study, we examined the effects of five years of reduced tillage on the physical properties of the soil and the dynamics of Agriotes wireworm populations (Elateridae), which are increasingly widespread pests. Our results show that tillage reduction led to stable edaphic conditions and a redistribution of organic matter, creating a favorable environment for wireworms. While our results demonstrate the beneficial effects of reduced tillage on aggregate stability, they also indicate a concomitant increase in soil bulk density, suggesting a reduction in water-holding capacity. Monitoring of wireworm populations revealed their aggregated distribution and their increase in abundance in infested areas year on year. Monitoring soil moisture revealed that tillage reduction improved water dynamics, enhancing infiltration and reducing evaporation. This could potentially favor the development of wireworms. Surprisingly, wireworm size distribution showed a higher proportion of young instars in plowed plots, evidencing that, firstly, the lack of soil cover does not prevent oviposition and that injury caused by plowing targets more the last instars rather than young larvae. While reduced tillage improves key soil health indicators, our findings suggest a potential trade-off in terms of increased pest pressure. Our study highlights the importance of adopting a holistic approach when designing sustainable cropping systems, as well as considering the services and dis-services they provide.

ecology↗

bioRxiv2025

The Towers Foraging Park: A Flexible Naturalistic Framework to Study Learning, Decision-Making, and Motor Control in Freely Moving Mice

Adaptive behavior depends on a variety of brain functions, such as learning, decision-making, spatial navigation and motor control, which have been studied using two main strategies. Trial-based tasks allow their mechanistic dissection but tend to generate highly stereotypical behavior, whereas open-field investigations capture naturalistic dynamics with less experimental control. To leverage the strengths of both approaches, we developed a behavioral framework which recreates dilemmas faced by animals during patch foraging. In the Tower Foraging Park (TFP), mice harvest rewards along square towers (patches) by making quarter-turns around them in a single direction (exploit) and alternating between towers (explore) as patches eventually deplete. Within a couple of sessions, naive mice performed quarter-turns in the rewarded direction with increasing vigor and reduced variability, and switched towers after short exploitation bouts. When the harvest direction was reversed, mice rapidly adapted their turning direction, with quarter-turn trajectory variability and speed becoming decoupled. Mice subjected to daily reversals adapted progressively faster, revealing meta-learning. When the next rewarding tower became harder to locate, all trained mice increased exploitation duration, although metalearners outperformed animals trained under stable contingencies. Altogether, the TFP produced behavior consistent with foraging theory and revealed new processes facilitating flexible foraging: meta-learning and the decoupling of movement variability and speed. Moreover, because the TFP accommodates diverse protocol variants, adheres to FAIR principles, and is fully compatible with modern neurophysiological techniques, it provides a promising platform for mechanistic investigations of brain functions underlying adaptive behavior while maintaining ethological validity.

animal behavior and cognition↗

bioRxiv2024

Running, Fast and Slow: The Dorsal Striatum Sets the Cost of Movement During Foraging

Humans and other animals adjust when and how fast they execute goal-directed actions according to expected costs and benefits. Yet, the behavioral principles and brain regions underlying adaptive vigor control remain poorly understood. Here, we developed a self-paced foraging task in which rats must run across a motorized treadmill to collect rewards, allowing separate manipulation of benefit (reward delivery probability) and cost (effort). Throughout the foraging sessions, run timing and speed jointly reflected the rats idiosyncratic urgency to obtain rewards. In contrast, when the cost of crossing the treadmill increased, rats ran faster to maintain a high reward rate while run timing remained stable. Consistent with distinct mechanisms for adapting to costs or benefits, dorsal striatum lesions primarily limited running speed under effortful conditions, whereas ventral striatum lesions reduced rewardseeking urgency at session onset. Together, these findings suggest that vigor is modulated by costs and benefits through distinct striatal circuits.

neuroscience↗