Venue: Neurocentre Magendie (conference room)
Pierre Le Merre
Department of Neuroscience | Karolinska Institutet
Functional maps of the mouse prefrontal cortex.
The mouse prefrontal cortex (PFC) lacks a definition. Further, the function(s) of the PFC remains to be established, regardless of species. Traditionally, subregions of the PFC have been delineated based on cytoarchitectural features. Based on recent large-scale mapping of the connectivity of the mouse cortex, a prefrontal module has been identified. The cortical subregions within this module (anterior cingulate (ACA), prelimbic area (PL), infralimbic area (ILA), orbitofrontal cortex (OFC)) display particularly high interconnectivity to each other than to other cortical regions. Hodology thus gives support for the presence of a distinct prefrontal region (module) in the mouse brain. However, how hodology and cytoarchitectural features relate to function is highly unclear. We here use a series of behavioral auditory tasks and high-density (Neuropixels probes) recordings in a head-restrained mice to establish functional maps of the mouse PFC. Thousands of single units were recorded across the layers and the proposed subregions of the PFC. At first, we extracted single unit features during spontaneous activity. We used functional connectivity and intrinsic timescales to establish a first hierarchical organization of PFC regions. We next used auditory stimuli to engage the subregions of the PFC while head-fixed mice passively listen to sounds or had to perform distinct behavioral tasks using the presented auditory stimuli. The presented data will focus on how functions segregate across the PFC during distinct behavioral auditory tasks, and how different prefrontal functions relate to traditional delineations of the PFC based on cytoarchitecture and/or hodology.
About Pierre Le Merre
I am a postdoc in Marie Carlén’s lab in Stockhlom interested in understanding what cognition means in biological terms and how abstract cognitive variables are implemented by cortical networks and brain regions such as the prefrontal cortex (PFC). During my PhD, I carried out two studies on cortical networks focusing on electrophysiological dynamics during behavioral states (Fernandez et al., 2017) and on their involvement in goal-directed sensorimotor transformations (Le Merre et al., 2018). To follow up on these findings, I devoted my postdoc project to understand the richness of mouse prefrontal cortex electrophysiological activities. I specialized as an electrophysiologist, performing high-density extracellular recordings (Neuropixels probes) combined with optogenetic tagging and perturbations. We recently submitted my first postdoc first author article (accessible on BioRXiv). My first author contribution to this study was to map activity signatures of aversive states in the mPFC. We are currently completing my second first author article revealing prefrontal functional differences during auditory processing with an unprecedented level of detail. We also wrote perspective article about the mouse prefrontal cortex to share our views and thoughts with the scientific community in a perspective article (Le Merre et al., 2021).
I would like now to come back to France and start my own lab developing new approaches to study working memory (brain-wide activity, voltage imaging) in the mouse. I am currently visiting different institutes to explore my comeback options. Bordeaux Neurocampus sounds like a perfect match and I would be honored to meet the scientific community and present my work to all interested researchers.
Fernandez, L.M.J., Comte, J.-C., Le Merre, P., Lin, J.-S., Salin, P.-A., and Crochet, S. (2017). Highly Dynamic Spatiotemporal Organization of Low-Frequency Activities During Behavioral States in the Mouse Cerebral Cortex. Cereb Cortex 27, 5444–5462.
Le Merre, P., Esmaeili, V., Charriere, E., Galan, K., Salin, P.-A., Petersen, C.C.H., and Crochet, S. (2018). Reward-Based Learning Drives Rapid Sensory Signals in Medial Prefrontal Cortex and Dorsal Hippocampus Necessary for Goal-Directed Behavior. Neuron 97, 83-91.e5.
Le Merre, P., Ährlund-Richter, S. and Carlén, M. The mouse prefrontal cortex: Unity in diversity. Neuron 109, (2021).
Calvigioni D.*, Fuzik J.*, Le Merre P.*, Slashcheva M., Jung F., Ortiz C., Lentini A., Csillag V., Graziano M., Nikolakopoulou I., Weglage M., Lazaridis I., Kim H., Lenzi I., Park H., Reinius B., Carl ́en, M., Meletis, K. Esr1+ hypothalamic-habenula neurons shape aversive states. (2022). BioRXiv.