Maintenance of postsynaptic neuronal excitability by a positive feedback loop of postsynaptic BDNF expression

Abstract

Experiments have demonstrated that in mice, the PVT strongly projects to the CeL and participates in the formation of fear memories by synaptic potentiation in the amygdala. Herein, we propose a mathematical model based on a positive feedback loop of BDNF expression and signaling to investigate PVT manipulation of synaptic potentiation. The model is validated by comparisons with experimental observations. We find that a high postsynaptic firing frequency after stimulation is induced by presynaptic ${\mathrm{Ca}}^{2+}$ when the rates of BDNF secretion from PVT and LA neurons to the CeL are above a threshold value. Moreover, the positive feedback of postsynaptic BDNF production is important for the maintenance of the high excitability of the ${\mathrm{SOM}}^{+}$ CeL neuron after stimulation. The model brings insight into the underlying mechanisms of PVT modulation of synaptic potentiation at LA-CeL synapses and provides a framework of understanding other similar processes associated with synaptic plasticity.

Keywords: Fear conditioning; Firing frequency; Positive feedback; Presynaptic ${\text{Ca}}^{2+}$; Synaptic potentiation.