CaHVA_SU2015_DCN

CaHVA_SU2015_DCN#

class braincell.channel.CaHVA_SU2015_DCN(size, perm=Quantity(7.5e-06, 'cm / s'), temp=Quantity(309.15, 'K'), qdeltat=1.0, name=None)#

HVA calcium current of the DCN model (Sudhakar 2015).

A GHK-driven, high-voltage-activated (HVA) calcium current with a single \(m^3\) activation gate, used for the deep cerebellar nucleus (DCN) neuron model of (Sudhakar et al., 2015) [2]:

\[\begin{split}\begin{aligned} I_{CaHVA} &= -P \cdot m^3 \cdot \Phi(V, [Ca]_i, [Ca]_o, T) \\ m_\infty &= \frac{1}{1 + \exp(-(V + 34.5) / -9.0)} \\ \tau_m &= \frac{1}{\dfrac{31.746}{\exp((V - 5) / -13.89) + 1} + \dfrac{3.97 \times 10^{-4} (V + 8.9)} {\exp((V + 8.9) / 5) - 1}} \Big/ q_{\Delta t} \end{aligned}\end{split}\]

where \(\Phi\) is the constant-field GHK flux (see ghk_flux()) evaluated with this class’s own inline Faraday/gas-constant literals rather than the shared helper (see Notes), and \(P\) is the permeability parameter.

Parameters:

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

  • perm (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Permeability entering the GHK flux term. Defaults to 7.5e-6 cm/s.

  • temp (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Absolute temperature entering the GHK flux term and the activation time constant. Defaults to 36 degrees Celsius.

  • qdeltat (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Divisor applied to \(\tau_m\); a NEURON-style Q10-free rate scale, not a Gate phi factor. Defaults to 1.0.

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

See also

CaLVA_SU2015_DCN

Sibling DCN calcium current using the same inline GHK constants and permeability parameterisation, with low-voltage-activated (\(m^2 h\)) gating instead.

CaL_SU2015_DCN

Sibling DCN calcium current with the same low-voltage-activated gating shape as CaLVA_SU2015_DCN, but driven ohmically against a fixed reversal potential rather than through GHK.

braincell.channel._base.ghk_flux

Shared GHK flux helper; this class does not call it directly (see Notes).

Notes

Ported from DCN/channel/CaHVA_SU15_DCN.mod, whose TITLE reads “High voltage activated calcium current (CaHVA) of deep cerebellar nucleus (DCN) neuron”. The origin of the DCN kinetics is the GENESIS model of Steuber, Schultheiss, Silver, De Schutter & Jaeger (2011) [1], translated from GENESIS to NEURON by Luthman, Hoebeek, Maex, Davey, Adams, De Zeeuw & Steuber (2011) and reused, without modification credit, in Sudhakar et al. (2015) [2]. The string “CaHVA” does not occur in the Sudhakar et al. (2015) article text; this docstring records only that the mechanism is part of the model published as [2], not that the paper names or describes it, and it does not claim that either paper prints the m_inf/tau_m constants above.

current() evaluates the GHK constant-field equation inline with the mod file’s own hard-coded literals (4.47814e6, -23.20764929) rather than calling ghk_flux(), matching the pattern used by the module-level _cav3p1_nmodl_ghk_flux / _cav3p3_nmodl_ghk_flux helpers elsewhere in this file. NEURON’s raw ica for this mechanism is outward-positive; the sign is flipped in current() to match BrainCell’s repo-wide inward-positive convention.

The original mechanism’s TABLE directive tabulated minf and taum over [-150, 100] mV (plus a DEPEND T table); BrainCell removes the table and evaluates both expressions per-call instead.

References

current(V, Ca)[source]#

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