K_Kv_test

class braincell.channel.K_Kv_test(size, g_max=Quantity(0., 'S / cm^2'), V_sh=Quantity(0., 'mV'), temp=Quantity(298.15, 'K'), Ra=Quantity(0.02, '10.0^6 * s^2 * A / (m^2 * kg)'), Rb=Quantity(0.006, '10.0^6 * s^2 * A / (m^2 * kg)'), q=Quantity(9., 'mV'), v12=Quantity(25., 'mV'), name=None)

Scratch Kv fixture built on the generic vtrap rate form.

A single-gate potassium channel whose activation uses the generic NEURON vtrap alpha/beta idiom, with the Boltzmann midpoint, slope and the two rate scales exposed as parameters:

\[\begin{split}\begin{aligned} n_\infty &= \frac{1}{1 + \exp(-(V' - v_{12}) / q)} \\ \alpha_n &= \frac{R_a (V' - v_{12})} {1 - \exp(-(V' - v_{12}) / q)} \\ \beta_n &= \frac{R_b (V' - v_{12})} {\exp((V' - v_{12}) / q) - 1} \\ \tau_n &= \frac{1}{\alpha_n + \beta_n} \end{aligned}\end{split}\]

where \(V' = (V - V_{sh}) / \mathrm{mV}\) and \(v_{12}\) and \(q\) are read in millivolts. The gate is declared in the inf/tau form, so \(\alpha_n\) and \(\beta_n\) above are assembled inside f_n_tau() rather than exposed as rate methods; the code writes \(\beta_n\) equivalently as \(-R_b (V' - v_{12}) / (1 - \exp((V' - v_{12}) / q))\).

This class is a fixture, not a model of a published mechanism – see Notes before using it for anything but exercising the template layer.

Parameters:

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

• g_max (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Maximal conductance density. Defaults to 0.0 S/cm2, i.e. an instance carries no current until it is set.

• V_sh (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Threshold shift applied to the rates, default 0.0 mV.

• temp (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Absolute temperature, default 25 degrees Celsius. Inert as shipped (see Notes).

• Ra (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Forward rate scale. Defaults to 0.02 / (mV ms).

• Rb (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Backward rate scale. Defaults to 0.006 / (mV ms).

• q (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Slope factor of the activation curve. Defaults to 9.0 mV.

• v12 (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Half-activation voltage. Defaults to 25.0 mV.

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

See also

K_HH1952

Delayed rectifier with a verified literature source, for a channel of this shape that is a model of something.

Notes

This class has no primary literature source, and that is a determination rather than an omission – though a weaker one than for the other citation-free symbols in this package. Three things mark it as a scratch or template fixture: its name, its zero default conductance, and its unit Q10. Its rate form is the generic vtrap alpha/beta idiom that recurs across dozens of unrelated NEURON kv.mod files and identifies no particular one. No specific source was pursued, which is not the same as establishing that none exists; if a later task identifies one, that is an addition rather than a contradiction of anything recorded here. The class therefore ships without a References section.

temp_ref (23 degrees Celsius) and Q10_n (1.0) are assigned in __init__() as fixed attributes rather than exposed as constructor parameters. temp enters the gate only through \(Q_{10}^{(T - T_{ref})/10}\), and with a unit Q10_n that factor is 1 at every temperature, so changing temp has no effect on this channel.

Numerical caveat. Unlike the sibling classes in this module, which route their linoids through exprel or an explicit where guard, f_n_tau() evaluates the two quotients directly. At exactly \(V' = v_{12}\) both are 0/0 and the method returns nan, although the limit is finite – \(1 / (q (R_a + R_b))\), about 4.3 ms with the shipped defaults. Away from that single point the expression is well-behaved.

root_type

alias of Potassium