CaT_HP1992

CaT_HP1992#

class braincell.channel.CaT_HP1992(size, g_max=Quantity(1.75, 'mS / cm^2'), temp=Quantity(309.15, 'K'), q10_p=5.0, temp_ref_p=Quantity(297.15, 'K'), q10_q=3.0, temp_ref_q=Quantity(297.15, 'K'), V_sh=Quantity(-3., 'mV'), name=None)#

Huguenard & Prince 1992 T-type calcium current for reticular nucleus.

The slowly inactivating transient (T-type) calcium current \(I_{Ts}\) recorded in rat thalamic reticular nucleus (nRt) neurons by (Huguenard & Prince, 1992) [1], with \(p^2 q\) HH gating and an ohmic driving force:

\[\begin{split}\begin{aligned} p_\infty &= \frac{1}{1 + \exp(-(V' + 52) / 7.4)} \\ \tau_p &= 3 + \frac{1} {\exp((V' + 27) / 10) + \exp(-(V' + 102) / 15)} \\ q_\infty &= \frac{1}{1 + \exp((V' + 80) / 5)} \\ \tau_q &= 85 + \frac{1} {\exp((V' + 48) / 4) + \exp(-(V' + 407) / 50)} \end{aligned}\end{split}\]

where \(V' = (V - V_{sh}) / \mathrm{mV}\) and \(\tau_p\)/\(\tau_q\) (in milliseconds) are further scaled by gate_phi().

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 1.75 mS/cm2.

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

  • q10_p (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Q10 scaling factor for the activation gate, default 5.0.

  • temp_ref_p (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Reference temperature for q10_p, default 24 degrees Celsius.

  • q10_q (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Q10 scaling factor for the inactivation gate, default 3.0.

  • temp_ref_q (Array | ndarray | bool | number | bool | int | float | complex | Quantity) – Reference temperature for q10_q, default 24 degrees Celsius.

  • V_sh (Array | ndarray | bool | number | bool | int | float | complex | Quantity | Callable) – Threshold shift applied to both gates’ rates, default -3.0 mV (see Notes).

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

See also

CaT_HM1992

Independently sourced low-threshold T-type current for thalamic relay neurons, with the same p^2 q gating shape but a different Boltzmann parameterisation.

Notes

Compared against IT2.mod (ModelDB accession 3670), whose header reads: “The kinetics is described by standard equations (NOT GHK) using a m2h format, according to the voltage-clamp data (whole cell patch clamp) of Huguenard & Prince, J Neurosci. 12: 3804-3817, 1992”, with “Q10 changed to 5 and 3”. Unlike CaT_HM1992, the mod file’s shift = 2 mV (screening charge for external calcium = 2 mM) is folded into every constant here – both the Boltzmann midpoints and the time-constant offsets – so all six mod-file numbers (50, 78, 25, 100, 46, 405) shift uniformly to the 52, 80, 27, 102, 48, 407 used above. q10_p = 5.0 and q10_q = 3.0 at temp_ref = 24 degC match the mod file’s phi_m = 5^((celsius-24)/10) and phi_h = 3^((celsius-24)/10) exactly.

This class applies a further V_sh = -3.0 mV on top of the already-folded 2 mV shift, so the shipped defaults sit 3 mV depolarized relative to IT2.mod’s own defaults. This is a documented free parameter, not a citation error. g_max = 1.75 mS/cm2 matches IT2.mod’s gcabar = 0.00175 mho/cm2.

References

root_type#

alias of Calcium