HCN_ZH2019_IO

class braincell.channel.HCN_ZH2019_IO(size, g_max=Quantity(0.15, 'mS / cm^2'), E=Quantity(-43., 'mV'), name=None)

Inferior olive somatic h-current, imported from HCN_ZH19_IO.mod.

A single-gate hyperpolarization-activated current for the single-compartment inferior olive somatic model of Zhang & Santaniello (2019) [2]. The gating kinetics originate in the inferior olive compartmental model of Schweighofer, Doya, & Kawato (1999) [1] and reached this class through the NEURON port of Torben-Nielsen, Segev, & Yarom (2012) (see Notes).

Parameters:

• size (int | Sequence[int] | integer | Sequence[integer]) – Channel state shape.

• g_max (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Maximum conductance, default 0.15 mS/cm2.

• E (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Fixed reversal potential used in place of an ion-derived driving force, default -43.0 mV.

• name (str | None) – Optional channel name.

Notes

The current is

\[I_h = g_{max} \, q \, (E - V)\]

with the single gate q following

\[q_\infty(V) = \frac{1}{1 + \exp\left(\dfrac{V + 75\ \text{mV}}{5.5\ \text{mV}}\right)}\]

\[\tau_q(V) = \frac{1}{\exp(-0.086\,V/\text{mV} - 14.6) + \exp(0.07\,V/\text{mV} - 1.87)}\ \text{ms}\]

q carries no phi/q10 in its Gate declaration, so gate_phi() resolves to the default 1.0 and neither rate method is temperature-scaled.

This mechanism is ported from IO/channel/HCN_ZH19_IO.mod, whose header credits “Somatic h channel from Schweighofer et al., 1999” and porter “Xu Zhang @ UConn, 6-22-2018”. The inferior olive neurons modelled by Zhang & Santaniello (2019) [2] are single-compartment (nseg = 1); this class must not be described as part of a multi-compartment inferior olive mechanism.

In the source .mod file the kinetics originate with Schweighofer, Doya, & Kawato (1999) [1] and reached HCN_ZH19_IO.mod through the intermediate NEURON port of Torben-Nielsen, Segev, & Yarom (2012), credited in the header as “B. Torben-Nielsen @ HUJI” on the sibling Na/Kdr/Ca files of the same deposit.

Import deviation. In the upstream .mod file the rates(v) call that refreshes q_inf/tau_q lives inside BREAKPOINT; in this deposit’s HCN_ZH19_IO.mod it was relocated into DERIVATIVE states, so the rates are refreshed before the cnexp state update rather than after it. This is a semantic change, not a cosmetic one – the only other difference from the upstream file is the SUFFIX rename, and the COMMENT header is otherwise untouched.

References

[1] (1,2)

Schweighofer, N., Doya, K., & Kawato, M. (1999). Electrophysiological properties of inferior olive neurons: A compartmental model. Journal of Neurophysiology, 82(2), 804-817. doi:10.1152/jn.1999.82.2.804

[2] (1,2)

Zhang, X., & Santaniello, S. (2019). Role of cerebellar GABAergic dysfunctions in the origins of essential tremor. Proceedings of the National Academy of Sciences of the United States of America, 116(27), 13592-13601. doi:10.1073/pnas.1817689116

reversal_potential(V, *ions)

Return the reversal potential driving the current.

Parameters:

• V (ArrayLike) – Membrane potential. Unused by the default implementation; present so overrides can depend on it.

• *ions (IonInfo) – Ion states, in the declaration order of root_type.

Returns:

Reversal potential, as a voltage. Defaults to that of the first ion, which for a joint root type is the first entry of root_type.__args__. Override to read a fixed self.E or a non-leading ion.

Return type:

ArrayLike

root_type

alias of HHTypedNeuron