Cav3p1Test_PC24

class braincell.channel.Cav3p1Test_PC24(size, g_max=Quantity(0.00025, 'S / cm^2'), temp=Quantity(295.15, 'K'), q10=3.0, temp_ref=Quantity(310.15, 'K'), name=None)

Cav3.1 test variant with the GHK drive replaced by a constant.

A test variant of the Cav3.1 mechanism whose gating kinetics are exactly those of Cav3p1_MA2024_PC – the Cav3.1 fit to (Iftinca et al., 2006) [1] published in (Anwar, Hong & De Schutter, 2012) [2] and imported for the human Purkinje cell model of (Masoli et al., 2024) [3] – but with the constant-field (GHK) drive replaced by a direct conductance-density current law:

\[I_{Ca} = g_{max} \, p^2 q\]

This ohmic form is not the published one. The published mechanism is a GHK-driven permeability; this variant is not, and its g_max = 2.5e-4 carries S/cm2 where the published mechanism’s pcabar = 2.5e-4 carries cm/s – the same number in a different dimension. The class name’s “Test” is accurate: nothing in the source file or the deposit indicates that this variant produced any published result. See Notes for what the current law does and does not depend on.

The steady-state and tau formulas, including the temperature factor embedded in the tau expressions and the V <= -90 mV constant branch of \(\tau_p\), are identical to Cav3p1_MA2020_GoC’s and are written out there.

Parameters:

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

• g_max (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Conductance density multiplying the gating product. Defaults to 2.5e-4 S/cm2 (see above and Notes). This class takes no V_sh, unlike its Cav3.1 siblings.

• temp (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Absolute temperature driving the qt factor. Defaults to 22 degrees Celsius. It does not enter a GHK term here, because there is none.

• q10 (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Q10 factor for qt. Defaults to 3.0.

• temp_ref (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Reference temperature for qt. Defaults to 37 degrees Celsius.

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

See also

Cav3p1_MA2024_PC

The published, GHK-driven Purkinje-cell mechanism this variant’s kinetics are taken from.

Cav3p1_MA2020_GoC

Where the full equation set and the tau-embedded temperature handling are documented.

Notes

Ported from PC/channel/Cav3_1_test.mod, which carries no TITLE, no COMMENT, no author line and no reference of any kind. Its provenance was established by comparison instead: it declares the same named parameter block and the same four rate expressions as PC/channel/Cav3p1_MA24_PC.mod, character for character, so it inherits that mechanism’s attribution chain. The sibling file Cav3_1_test2.mod is claimed by no BrainCell symbol.

The single difference between the two files is the current law. Cav3p1_MA24_PC.mod computes ica = (1e3) * pcabar * m*m*h * g with g from GHK and pcabar in cm/s; Cav3_1_test.mod drops the GHK drive entirely, redeclares pcabar = 2.5e-4 (S/cm2) as a conductance density and computes ica = pcabar * m*m*h. That right-hand side is dimensionally inconsistent with the (mA/cm2) the same file declares for ica, so BrainCell’s current() multiplies by 1 mV purely to lift the value to a current-density unit that can flow through the standard compare/runtime paths. The multiplier is a fixed constant, not a driving force: the resulting current carries no (v - eca) factor and no GHK factor, and therefore depends on voltage only through the gates.

current() also negates the result, as every imported mechanism in this module does, to match BrainCell’s repo-wide inward-positive convention against NEURON’s outward-positive ica.

No import deviations are recorded for this mechanism: the file carries no TABLE, no derivimplicit and no rate-refresh relocation, and it appears in none of the comparison suite’s deviation tables.

References

[1]

Iftinca, M., McKay, B. E., Snutch, T. P., McRory, J. E., Turner, R. W., & Zamponi, G. W. (2006). Temperature dependence of T-type calcium channel gating. Neuroscience, 142(4), 1031-1042. doi:10.1016/j.neuroscience.2006.07.010

[2]

Anwar, H., Hong, S., & De Schutter, E. (2012). Controlling Ca2+-activated K+ channels with models of Ca2+ buffering in Purkinje cells. The Cerebellum, 11(3), 681-693. doi:10.1007/s12311-010-0224-3

[3]

Masoli, S., Sanchez-Ponce, D., Vrieler, N., Abu-Haya, K., Lerner, V., Shahar, T., Nedelescu, H., Rizza, M. F., Benavides-Piccione, R., DeFelipe, J., Yarom, Y., Munoz, A., & D’Angelo, E. (2024). Human Purkinje cells outperform mouse Purkinje cells in dendritic complexity and computational capacity. Communications Biology, 7(1), 5. doi:10.1038/s42003-023-05689-y

current(V, Ca)

Calculate the current for this ion channel.

This method should be implemented by subclasses to compute the current based on the channel’s specific properties and state.

Parameters:

• *args – Variable length argument list.

• **kwargs – Arbitrary keyword arguments.

Raises:

NotImplementedError – This method must be implemented by subclasses.

root_type

alias of Calcium