Channel Density Regulation of Firing Patterns in a Cortical Neuron Model

Abstract

Modifying the density and distribution of ion channels in a neuron (by natural up- and downregulation or by pharmacological intervention or by spontaneous mutations) changes its activity pattern. In this investigation we analyzed how the impulse patterns are regulated by the density of voltage-gated channels in a neuron model based on voltage-clamp measurements of hippocampal interneurons. At least three distinct oscillatory patterns, associated with three distinct regions in the Na-K channel density plane, were found. A stability analysis showed that the different regions are characterized by saddle-node, double-orbit, and Hopf-bifurcation threshold dynamics, respectively. Single, strongly graded action potentials occur in an area outside the oscillatory regions, but less graded action potentials occur together with repetitive firing over a considerable range of channel densities. The relationship found here between channel densities and oscillatory behavior may partly explain the difference between the principal spiking patterns previously described for crab axons (class 1 and 2) and cortical neurons (regular firing and fast spiking).

Neuronal Electrophysiological Function and Control of Neurite Outgrowth on Electrospun Polymer Nanofibers Are Cell Type Dependent

“…The model suggests that once an adequate ratio of Na + to K + current densities is reached, repeated APs will not decline in amplitude and cells will function as mature neurons. 47,48 This decline in repeated AP amplitude was observed in hippocampal cells within this study (Fig. 3A), with improvement over time in culture to reach minimal repeated AP amplitude decline by 25 DIV.…”

GABA regulates resonance and spike rate encoding via a universal mechanism that underlies the modulation of action potential generation

“…The ordinary Bogdanov-Takens bifurcation has been characterized as an organizing center for transitions to resonance (Izhikevich, 2010;Ermentrout & Terman, 2010) and saddle-node-loop points to induce bistability (Izhikevich, 2010;Ermentrout & Terman, 2010). Potassium channel density can induce changes in excitability class as observed in simulations of fly neurons (Berger & Crook, 2015) and cortical neurons (Golomb et al, 1997;Arhem et al, 2006;Arhem & Blomberg, 2007;Zeberg et al, 2015). The BTC-structure captures these individual transitions in a single unifying framework.…”

The firing patterns of spinal neurons: in situ patch‐clamp recordings reveal a key role for potassium currents

“…The dominant role of sodium currents in depolarisation in RB neurons is supported by the limited changes that occur in the action potentials of these neurons when highvoltage-activated calcium channels are blocked (Winlove & Roberts, 2011). Some modelling suggests that high densities of I NaT can facilitate repetitive firing by allowing neurons to lie in oscillatory regions of the sodium-potassium current density plane (Matzner & Devor, 1992;Arhem et al, 2006). This does not appear to be the case in our experiments, as we found the highest sodium current density in neurons that fire only a single action potential in response to depolarising current.…”