Perineuronal nets (PNNs) surrounding fast-spiking basket cells, have been suggested to reduce the capacitance of the cell membrane and thereby effecting the firing properties of the neurons. However, there have been conflicting evidence whether breaking down PNNs increased membrane capacitance and decreased neuron firing rates. In this study, we examined how this change in capacitance affects firing rates using various computational neuron models.
In the current study, we showed for a selection of nine computational neuron models, that the reported reduction in capacitance indeed lead to reduced firing rate, but could not explain a reduction as large as that seen in the experiments. We therefore hypothesized that the reduction in f was due to a combination of cellular mechanisms affected by PNN degradation.
By systematically exploring how f was reduced by changes in selected model parameters, we proposed an explanation where the reduced firing rate
in experiments could be due to
(1) the reported change in capacitance combined with
(2) upregulation of potassium channels
(3) upward shifts in Ca and Na reversal potentials.
Whereas the upregulation of is supported by previous experimental data (Dembitskaya et al., 2021), the proposed effects of PNN degradation on the remaining parameters are neither supported nor conflicted by existing literature.
The paper:
Kine Ødegård Hanssen, Sverre Grødem, Marianne Fyhn, Torkel Hafting, Gaute T. Einevoll, Torbjørn Vefferstad Ness & Geir Halnes