CaN_IS2008

CaN_IS2008#

class braincell.channel.CaN_IS2008(size, E=Quantity(10., 'mV'), g_max=Quantity(1., 'mS / cm^2'), temp=Quantity(309.15, 'K'), q10=1.0, temp_ref=Quantity(309.15, 'K'), name=None)#

Inoue & Strowbridge 2008 Ca-activated nonselective cation current.

A calcium- and voltage-dependent non-selective cation current (\(I_{CAN}\)) gated by a single activation variable and scaled by a saturating calcium-modulation factor:

\[\begin{split}\begin{aligned} I_{CAN} &= \bar g \cdot M([Ca]_i) \cdot p \cdot (E - V) \\ M([Ca]_i) &= \frac{[Ca]_i}{[Ca]_i + 0.2\ \mathrm{mM}} \\ p_\infty &= \frac{1}{1 + \exp(-(V + 43) / 5.2)} \\ \tau_p &= \frac{2.7}{\exp(-(V + 55) / 15) + \exp((V + 55) / 15)} + 1.6 \end{aligned}\end{split}\]

where \(V\) is read in millivolts, \([Ca]_i\) is the intracellular calcium concentration, and \(p\) relaxes toward \(p_\infty\) with time constant \(\tau_p\) (in milliseconds) scaled by gate_phi().

Parameters:

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

  • E (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Reversal potential. Defaults to 10.0 mV.

  • g_max (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Maximal conductance density. Defaults to 1.0 mS/cm2.

  • temp (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Absolute temperature driving the Q10 factor, default 36 degrees Celsius.

  • q10 (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Q10 scaling factor for the activation gate, default 1.0 (no temperature scaling at the reference temperature).

  • temp_ref (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Reference temperature for the Q10 formula, default 36 degrees Celsius.

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

See also

CaL_IS2008

Sibling channel from the same source paper, whose L-type attribution is contradicted by the paper’s own text (see its Notes).

Notes

Ported verbatim from BrainPy’s ICaN_IS2008 (brainpy/dyn/channels/calcium.py): every rate constant and the M([Ca]_i) modulation term match exactly. BrainPy in turn attributes the current to two sources, only one of which is Inoue & Strowbridge (2008): the M([Ca]_i) = [Ca]_i / ([Ca]_i + 0.2 mM) modulation is the calcium-activated non-selective cation form used by Destexhe, Contreras, Steriade, Sejnowski & Huguenard (1994), while the voltage dependence of p is attributed to Inoue & Strowbridge (2008).

Inoue, T., & Strowbridge, B. W. (2008) models a calcium- and voltage-dependent nonselective cation current (\(I_{CAN}\)) in an olfactory bulb granule-cell model, where it generates the calcium-dependent afterdepolarization central to the paper’s thesis about persistent activity – this substantially supports the attribution of this class to that paper. However, the paper’s Methods defer the gating constants to supplementary materials that are not included with the PMC-deposited author manuscript and were not otherwise obtainable, and no ModelDB deposit exists for this paper. No published source has been read that prints the p_inf/tau_p constants above, so this docstring ships no References section: the current is documented as a ported implementation of substantially supported but not fully confirmed provenance, not as a transcription of a specific paper’s printed equations.

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