Biology subjects

Bourg, J.

Publications and source records attributed to Bourg, J..

3 recordsLinked to original sources

bioRxiv2026

A plant-based biostimulant modulates grapevine susceptibility within a realistic water stress window through priming and phenylpropanoid pathway regulation

Fluctuating extreme weather events, coupled with rising average temperatures, can severely impact grapevine physiology and yield. While biostimulants have been gaining acceptance as a short-terms tools to enhance grapevine resilience, their adoption is hindered by inconsistent efficacy, partly driven by unpredictable plant stress levels. Over two contrasting seasons, we integrated physiological, transcriptomic, and metabolomic analyses to investigate how a plant-based biostimulant modulates the sensibility of Vitis vinifera under varying intensities of heat, drought, and their combination. This panel of water status, ranging from -0.02 to -1.6 MPa, revealed that the physiological response induced by the biostimulant treatment alleviates water stress within a field-relevant hydraulic window located between -0.4 and -1.2 MPa. Moreover, moderate but constitutive reduction of growth parameters in biostimulant plants, suggests a trade-off between vegetative development and abiotic stress responses. Accordingly, gene expression analysis revealed an interaction between water availability and the plant response to the biostimulant, which suggest an activation of priming mechanisms. Metabolic profiling supported these findings, highlighting the central role of phenylpropanoid pathway modulation, together with adjustments in ROS dynamics and stress-related hormone responses, particularly abscisic acid. Overall, this work emphasizes the need for integrating detailed plant water status and leaf gas exchange to accurately evaluate biostimulant performances under abiotic stress.

plant biology↗

bioRxiv2022

Emergence of a time-independent population code in auditory cortex enables sound categorization and discrimination learning

The temporal structure of sensory inputs contains essential information for their interpretation by the brain1-9. Sensory systems represent these temporal cues through two codes: the temporal sequences of neuronal activity and the spatial patterns of neuronal firing rate3,7,10-20. However, it is still unknown which of these two coexisting codes causally drives sensory decisions3,10,20,21. To separate their contributions, we designed an optogenetic stimulation paradigm in the mouse auditory cortex to generate neuronal activity patterns differing exclusively along their temporal or spatial dimensions. Training mice to discriminate these patterns shows that they efficiently learn to discriminate spatial but not temporal patterns, indicating that spatial representations are necessary for sensory learning. In line with this result, we observed, based on large-scale neuronal recordings of the auditory system, that the auditory cortex is the first region in which spatial patterns efficiently represent temporal auditory cues varying over several hundred milliseconds. This feature is shared by the deep layers of neural networks trained to categorise time-varying sounds. Therefore, the emergence of a spatial code for temporal sensory cues is a necessary condition to associate temporally structured stimuli to decisions. We expect this constraint to be crucial for re-engineering perception by cortical stimulation.

neuroscience↗

bioRxiv2018

Cortical recruitment determines learning dynamics and strategy

Salience is a broad and widely used concept in neuroscience whose neuronal correlates, however, remain elusive. In behavioral conditioning, salience is used to explain various effects, such as stimulus overshadowing, and refers to how fast and strongly a stimulus can be associated with a conditioned event. Here, we show that sounds of diverse quality, but equal intensity and perceptual detectability, can recruit different levels of population activity in mouse auditory cortex. When using these sounds as cues in a Go/NoGo discrimination task, the degree of cortical recruitment matches the salience parameter of a reinforcement learning model used to analyze learning speed. We test an essential prediction of this model by training mice to discriminate light-sculpted optogenetic activity patterns in auditory cortex, and verify that cortical recruitment causally determines association or overshadowing of the stimulus components. This demonstrates that cortical recruitment underlies major aspects of stimulus salience during reinforcement learning.

neuroscience↗