Transsynaptic modulation of presynaptic short-term plasticity in hippocampal mossy fiber synapses

Abstract The hippocampal mossy fiber synapse is a key of the trisynaptic circuit. Post-tetanic potentiation (PTP) most powerful form plasticity at this synaptic connection. It widely believed that PTP an entirely presynaptic phenomenon, implying induction input-specific, and requires neither activity multiple inputs nor stimulation postsynaptic neurons. To directly test cooperativity associativity, we made paired recordings between single terminals CA3 pyramidal neurons in rat brain slices. By stimulating non-overlapping converging onto neurons, confirm input-specific non-cooperative. Unexpectedly, exhibits anti-associative properties. EPSCs show only minimal after combined pre- high-frequency with intact Ca 2+ signaling, but marked absence spiking suppression signaling (10 mM EGTA). largely recovered by inhibitors voltage-gated R- L-type channels, group II mGluRs, vacuolar-type H + -ATPase, suggesting involvement retrograde vesicular glutamate signaling. Transsynaptic regulation extends repertoire computations, implementing brake on detonation “smart teacher” function synapses.