May 2 – 11:00am
Andreas Frick

May 5 – 9:00am
Cyril Herry (University of Bordeaux, France)
Decoding defensive systems

from Frick's lab will defend her thesis entitled 'Determine how intrinsic excitability plasticity of defined neuronal engram ensembles in the anterior cingulate cortex influences the precision of remote memory'

Title
Determine how intrinsic excitability plasticity of defined neuronal engram ensembles in the anterior cingulate cortex influences the precision of remote memory

Abstract
Associative memories are progressively stored and stabilised in neocortical circuits during systems-level memory consolidation. The anterior cingulate cortex (ACC) is hypothesised to play a key role in the formation of memory for distant but not recent contextual fears. In addition to synaptic plasticity, intrinsic plasticity is also a crucial contributor to learning and memory, particularly in the dynamic aspect of memory such as allocation and consolidation. A plasticity change in the intrinsic excitability of engram sets following a learning experience is an interesting permissive mechanism for the formation of a memory trace. However, little is known about the plasticity of learning-induced intrinsic excitability in the neocortex and its functional relevance for remote contextual fear memory.

This thesis investigated the change in intrinsic excitability of putative ACC engram sets induced by contextual fear conditioning and how chemogenetic modification of excitability in these neurons during the memory consolidation phase might influence the accuracy of remote memory.

First, we used a c-fos-dependent labelling system, TetTag mice and doxycycline, combined with virally encoded tools allowing the identification and visualisation of ACC neurons explicitly engaged in the encoding phase of contextual fear conditioning. The organisation of these engrammed neurons in the different layers of the ACC was also compared. Next, using ex vivo whole-cell recordings of putative engram neurons from acute brain slices of the ACC, we characterised the intrinsic properties of these neurons after contextual fear conditioning. Finally, we used a chemogenetic approach, based on the excitatory or inhibitory DREADD (designer receptor exclusively activated by designer drugs) expressed in CCA engram assemblies to assess the functional role of intrinsic excitability plasticity in different phases of memory formation and accuracy. In addition, we designed memory interference experiments to examine the effect of suppressing ACC engram sets in remote memory accuracy with DREADD.

Taken together, our study suggests a critical role of intrinsic excitability plasticity in the putative ACC engram sets during the early phase of contextual fear memory consolidation for remote memory formation and accuracy.

Key words
Intrinsic excitability plasticity, Engram clusters, Remote memory, Anterior cingulate cortex


Jury
Christophe MULLE (President/ Examiner)
Gisella VETERE (Rapporteur)
Matthew NOLAN (Rapporteur)
Lisa ROUX (Guest)
Andreas Frick (Thesis Director)
Date de la soutenance: 14/09/2021 - 14h00
Lieu: Videoconference

Pour plus de détails: https://www.bordeaux-neurocampus.fr/event/soutenance-de-these-liangying-zhu/

Congratulations to the Magendie laureates!

CE13 – Biologie Cellulaire, biologie du développement et de l’évolution
Catégorie PRC :
SelfMorphogEar : Auto-organisation d’un épithélium sensoriel: bases moléculaires, cellulaires et mécaniques de l’extension et du remodelage cochléaires.
Raphael Etournay (Institut Pasteur/Institut de l’Audition) / Mireille Montcouquiol (Magendie - Eq Montcouquiol-Sans)

CE14 – Physiologie et physiopathologie
Catégorie PRC :
StriaPOM : Rôle du circuit POMC-striatum ventral dans le développement de l’obésité
Daniela Cota (Magendie) / Xavier Fioramonti (Nutrineuro), Pierre Trifilieff (Nutrineuro)

CE16 – Neurosciences moléculaires et cellulaires – Neurobiologie du développement
Catégorie PRC :
EMTSens : Plasticité électro-morpho-transcriptomique des réseaux spinaux dans un contexte de perception sensorielle atypique
Yves Le Feuvre (Magendie - Eq Frick)

CE37 – Neurosciences intégratives et cognitives
Catégorie PRC :
RejuvBrain : La néo-neurogénèse hippocampique : une nouvelle stratégie pour rajeunir le cerveau vieillissant.
Nora Abrous (Magendie) / Stéphane Oliet (Magendie)

CE44 – Biochimie du Vivant
Catégorie PRC :
BrainFuel : Rôle des différents substrats énergétiques pour l’activité cérébrale
Luc Pellerin (IRTOMIT, Poitiers) / Aude Panatier (Magendie - Eq Oliet), Anne-Karine Bouzier-Sore (CRMSB, Bordeaux), Céline Baligand (LMN, Fontenay-aux-roses).

Andreas Frick (Neurocentre Magendie) has received a Research Award from the Simons Foundation Autism Research Initiative (SFARI).

His project:
Atypical sensory experience is a core feature of Autism Spectrum Disorder (ASD) and may be strongly determinant of other core symptoms of the disorder. Atypical sensory information processing, and associated behavioral symptoms related to the perception of touch, are very common in ASD and exert a strong negative influence on day-to-day life. Nonetheless, there is a surprising paucity of neurobiological studies addressing this aspect of ASD pathology, or specifically attempting to target this symptom for therapeutic rescue. In collaboration with Prof. S. Heinemann (Friedrich-Schiller-University Jena), they are exploring a novel therapeutic strategy for treating sensory symptoms in ASD.

Pièces jointes