Biology subjects

Fabre, J. M.

Publications and source records attributed to Fabre, J. M..

4 recordsLinked to original sources

bioRxiv2026

The basal ganglia transform visual identity into behavioral relevance

The basal ganglia are thought to be essential for transforming sensory signals into appropriate actions, yet it remains unclear how this transformation unfolds across their nuclei. We recorded neuronal activity across the striatum, globus pallidus external (GPe), and substantia nigra pars reticulata (SNr) in mice that were either naive or trained in visuomotor associations. In naive mice, visual stimuli drove responses in all three nuclei. These responses were feature-selective in the striatum but less so in GPe and SNr. Task training potentiated visual responses across the circuit, particularly for stimuli associated with movement. Training affected nuclei differently: while the striatum continued to distinguish between stimuli associated with the same behavioral action, GPe and SNr did not, responding similarly to all "Go" cues while distinguishing them from "No-Go" cues. These results demonstrate that the basal ganglia progressively transform high-dimensional sensory representations into low-dimensional signals of behavioral relevance.

neuroscience↗

bioRxiv2023

Reusable, flexible, and lightweight chronic implants for Neuropixels probes

Electrophysiology has proven invaluable to record neural activity, and the development of Neuropixels probes dramatically increased the number of recorded neurons. These probes are often implanted acutely, but acute recordings cannot be performed in freely moving animals and the recorded neurons cannot be tracked across days. To study key behaviors such as navigation, learning, and memory formation, the probes must be implanted chronically. An ideal chronic implant should (1) allow stable recordings of neurons for weeks; (2) allow reuse of the probes after explantation; (3) be light enough for use in mice. Here, we present the "Apollo Implant", an open-source and editable device that meets these criteria and accommodates up to two Neuropixels 1.0 or 2.0 probes. The implant comprises a "payload" module which is attached to the probe and is recoverable, and a "docking" module which is cemented to the skull. The design is adjustable, making it easy to change the distance between probes, the angle of insertion, and the depth of insertion. We tested the implant across eight labs in head-fixed mice, freely moving mice, and freely moving rats. The number of neurons recorded across days was stable, even after repeated implantations of the same probe. The Apollo implant provides an inexpensive, lightweight, and flexible solution for reusable chronic Neuropixels recordings.

neuroscience↗

bioRxiv2022

Visuomotor learning promotes visually evoked activity in the medial prefrontal cortex

The medial prefrontal cortex (mPFC) is necessary for executing many learned associations between stimuli and movement. It is unclear, however, whether activity in the mPFC reflects sensory or motor aspects of sensorimotor associations and whether it evolves gradually during learning. To address these questions, we recorded cortical activity with widefield calcium imaging while mice learned a visuomotor task. The task involved associating a visual stimulus with a forelimb movement. After learning, the mPFC showed stimulus-evoked activity both during task performance and during passive viewing, when the stimulus evoked no action. This stimulus-evoked activity closely tracked behavioral performance across training, exhibiting jumps between training days. Electrophysiological recordings localized this activity to the secondary motor and anterior cingulate cortex. We conclude that learning a visuomotor task promotes a route for visual information to reach the prefrontal cortex, which develops responses to the relevant visual stimuli even outside the context of the task.

neuroscience↗

bioRxiv2022

Microglial TNFα controls GABAAR plasticity, slow waves and memory consolidation during sleep

Microglia sense the changes in their environment. How microglia actively translate these changes into suitable cues to adapt brain physiology is unknown. We reveal an activity-dependent regulation of cortical inhibitory synapses by microglia, driven by purinergic signaling acting on P2RX7 and mediated by microglia-derived TNF. We demonstrate that sleep induces microglia-dependent synaptic enrichment of GABAARs in a manner dependent on microglial TNF and P2RX7. We further show that microglia-specific depletion of TNF alters slow waves during NREM sleep and blunt memory consolidation in sleep-dependent learning tasks. Together, our results reveal that microglia orchestrate sleep-intrinsic plasticity of synaptic GABAARs, sculpt sleep slow waves and support memory consolidation.

neuroscience↗