Neocortical Layer-5 tLTD Relies on Non-Ionotropic Presynaptic NMDA Receptor Signaling

In the textbook view, NMDA receptors (NMDARs) act as coincidence detectors in Hebbian plasticity by fluxing Ca2+ when simultaneously depolarized and glutamate bound. Hebbian coincidence detection requires that NMDARs be located postsynaptically, but enigmatic presynaptic NMDARs (preNMDARs) also exist. It is known that preNMDARs regulate neurotransmitter release, but precisely how remains poorly understood. Emerging evidence suggest that NMDARs can also signal non-ionotropically, without the need for Ca2+ flux. At synapses between developing visual cortex layer-5 (L5) pyramidal cells (PCs), preNMDARs rely on Mg2+ and Rab3-interacting molecule 1αβ (RIM1αβ) to regulate evoked release during periods of high-frequency firing, but they signal non-ionotropically via c-Jun N-terminal kinase 2 (JNK2) to regulate spontaneous release regardless of frequency. At the same synapses, timing-dependent long-term depression (tLTD) depends on preNMDARs but not on frequency. We therefore tested if tLTD rel..., , # Data for Thomazeau *et al.*, 'Neocortical Layer-5 tLTD Relies on Non-Ionotropic Presynaptic NMDA Receptor Signaling', eLife 2025

Dataset DOI: [10.5061/dryad.3n5tb2rwb](10.5061/dryad.3n5tb2rwb)

## Data description

We induced spike-timing dependent depression or potentiation in synaptically coupled primary visual cortex layer-5 pyramidal cells using in vitro whole-cell patch clamp electrophysiology in mouse tissue under various genetic or pharmacological conditions. This dataset was acquired with custom software **MultiPatch** ([https://github.com/pj-sjostrom/MultiPatch](https://github.com/pj-sjostrom/MultiPatch)), running in **Igor Pro** (Wavemetrics Inc).

In current clamp mode, synaptically coupled PC→PC connections were identified by evoking five spikes at 30 Hz by 5-ms-long current injections of ~1.3 nA magnitude, repeated every 20 seconds, and averaged across 10–20 repetitions. We induced:

* **tLTD**: Postsynaptic firing 25 ms before presynaptic, either at:
* **20 Hz**: High...,