PhD seminar – Manuel Valero

Friday 22 May at 11:30

Venue: Centre Broca

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Dr. Manuel Valero

IMIM, Barcelona, Spain

Invited by Julia Welte (Neurocentre Magendie)

Title

Cell-Type-Specific Inhibitory Mechanisms of Memory Reactivation

Abstract

Memories are thought to be consolidated through the reactivation of neuronal assemblies during high-frequency hippocampal events, including sharp-wave ripples (SPW-Rs) and fast gamma oscillations. However, the circuit mechanisms governing the formation and stabilization of these assemblies remain poorly understood.

Using silicon probes integrated with miniaturized LEDs, we developed an approach to generate synthetic neuronal assemblies in vivo by selectively coactivating groups of CA1 pyramidal neurons in behaving mice. This approach allowed us to dissect the mechanisms underlying assembly formation in the hippocampus.

Our results show that only high-frequency coactivation patterns induce persistent assembly formation and memory-reactivation-like dynamics, despite other stimulation protocols producing similar levels of excitation. High-frequency stimulation uniquely recruits facilitating inhibitory responses mediated by specific interneuron populations, including somatostatin and subsets of parvalbumin interneurons. The strength of inhibitory recruitment predicts the stabilization of induced assemblies and selectively suppresses competing activity patterns during subsequent sleep.

Finally, we present evidence suggesting that similar inhibitory mechanisms operate during naturally occurring learning-related assembly formation and memory reactivation, supporting a broader role for inhibitory plasticity in organizing hippocampal population dynamics during memory consolidation.

Key publications

Valero M†*, Abad-Perez P†, Gallardo A, Picco M, García-Hernandez R, Brotons J, Martínez-Félix A, Machold R, Rudy B, Buzsáki G*.
Cooperative actions of interneuron families support the hippocampal spatial code.
Science. 389, 6764 (2025).

Valero M*, Zutshi I, Yoon E, Buzsáki G*.
Probing subthreshold dynamics of hippocampal neurons by pulsed optogenetics.
Science. 375 (6580), 570-574 (2022).

Valero M, Navas-Olive A, Menendez de la Prida L, Buzsáki G.
Inhibitory conductance controls place field dynamics in the hippocampus.
Cell Reports. 40 (8), 111232 (2022).

Meet the speaker!

You are a research staff ? Write to Julia Goncalves who will organize the schedule.

You are a PhD student? You can register to share some pizza after the talk. 

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PhD seminars are organized by the NBA, Bordeaux Neurocampus, and the Bordeaux Neurocampus Graduate Program.