The hippocampal mossy fiber synapse is a key synapse of the trisynaptic circuit. Post-tetanic potentiation (PTP) is the most powerful form of plasticity at this synaptic connection. It is widely believed that mossy fiber PTP is an entirely presynaptic phenomenon, implying that PTP induction is input-specific, and requires neither activity of multiple inputs nor stimulation of postsynaptic neurons. To directly test cooperativity and associativity, we made paired recordings between single mossy fiber terminals and postsynaptic CA3 pyramidal neurons in rat brain slices. By stimulating non-overlapping mossy fiber inputs converging onto single CA3 neurons, we confirm that PTP is input-specific and non-cooperative. Unexpectedly, mossy fiber PTP exhibits anti-associative induction properties. EPSCs show only minimal PTP after combined pre- and postsynaptic high-frequency stimulation with intact postsynaptic Ca2+ signaling, but marked PTP in the absence of postsynaptic spiking and after suppression of postsynaptic Ca2+ signaling (10 mM EGTA). PTP is largely recovered by inhibitors of voltage-gated R- and L-type Ca2+ channels, group II mGluRs, and vacuolar-type H+-ATPase, suggesting the involvement of retrograde vesicular glutamate signaling. Transsynaptic regulation of PTP extends the repertoire of synaptic computations, implementing a brake on mossy fiber detonation and a “smart teacher” function of hippocampal mossy fiber synapses.
We thank Drs. Carolina Borges-Merjane and Jose Guzman for critically reading the manuscript, and Pablo Castillo for discussions. We are grateful to Alois Schlögl for help with analysis, Florian Marr for excellent technical assistance and cell reconstruction, Christina Altmutter for technical help, Eleftheria Kralli-Beller for manuscript editing, and the Scientific Service Units of IST Austria for support. This project received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 692692) and the Fond zur Förderung der Wissenschaftlichen Forschung (Z 312-B27, Wittgenstein award), both to P.J.
Vandael DH, Okamoto Y, Jonas PM. Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses. Nature Communications. 2021;12(1). doi:10.1038/s41467-021-23153-5
Vandael, D. H., Okamoto, Y., & Jonas, P. M. (2021). Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses. Nature Communications. Springer. https://doi.org/10.1038/s41467-021-23153-5
Vandael, David H, Yuji Okamoto, and Peter M Jonas. “Transsynaptic Modulation of Presynaptic Short-Term Plasticity in Hippocampal Mossy Fiber Synapses.” Nature Communications. Springer, 2021. https://doi.org/10.1038/s41467-021-23153-5.
D. H. Vandael, Y. Okamoto, and P. M. Jonas, “Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses,” Nature Communications, vol. 12, no. 1. Springer, 2021.
Vandael DH, Okamoto Y, Jonas PM. 2021. Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses. Nature Communications. 12(1), 2912.
Vandael, David H., et al. “Transsynaptic Modulation of Presynaptic Short-Term Plasticity in Hippocampal Mossy Fiber Synapses.” Nature Communications, vol. 12, no. 1, 2912, Springer, 2021, doi:10.1038/s41467-021-23153-5.
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