# brainpy.dyn.channels.ICaHT#

class brainpy.dyn.channels.ICaHT(size, T=36.0, T_base_p=3.55, T_base_q=3.0, g_max=2.0, V_sh=25.0, method='exp_auto', name=None)[source]#

The high-threshold T-type calcium current model.

The high-threshold T-type calcium current model is adopted from 1. Its dynamics is given by

\begin{split}\begin{aligned} I_{\mathrm{Ca/HT}} &= g_{\mathrm{max}} p^2 q (V-E_{Ca}) \\ {dp \over dt} &= {\phi_{p} \cdot (p_{\infty} - p) \over \tau_{p}} \\ &\tau_{p} =\frac{1}{\exp \left(\frac{V+132-V_{sh}}{-16.7}\right)+\exp \left(\frac{V+16.8-V_{sh}}{18.2}\right)}+0.612 \\ & p_{\infty} = {1 \over 1+exp[-(V+59-V_{sh}) / 6.2]} \\ {dq \over dt} &= {\phi_{q} \cdot (q_{\infty} - h) \over \tau_{q}} \\ & \begin{array}{l} \tau_q = \exp \left(\frac{V+467-V_{sh}}{66.6}\right) \quad V< (-80 +V_{sh})\, mV \\ \tau_q = \exp \left(\frac{V+22-V_{sh}}{-10.5}\right)+28 \quad V \geq (-80 + V_{sh})\, mV \end{array} \\ &q_{\infty} = {1 \over 1+exp[(V+83 -V_{shift})/4]} \end{aligned}\end{split}

where $$phi_p = 3.55^{\frac{T-24}{10}}$$ and $$phi_q = 3^{\frac{T-24}{10}}$$ are temperature-dependent factors ($$T$$ is the temperature in Celsius), $$E_{Ca}$$ is the reversal potential of Calcium channel.

Parameters
• T (float) – The temperature.

• T_base_p (float) – The base temperature factor of $$p$$ channel.

• T_base_q (float) – The base temperature factor of $$q$$ channel.

• g_max (float) – The maximum conductance.

• V_sh (float) – The membrane potential shift.

References

1

Huguenard JR, McCormick DA (1992) Simulation of the currents involved in rhythmic oscillations in thalamic relay neurons. J Neurophysiol 68:1373–1383.

__init__(size, T=36.0, T_base_p=3.55, T_base_q=3.0, g_max=2.0, V_sh=25.0, method='exp_auto', name=None)[source]#

Methods

 __init__(size[, T, T_base_p, T_base_q, ...]) current(V, C_Ca, E_Ca) dp(p, t, V) dq(q, t, V) get_delay_data(name, delay_step, *indices) Get delay data according to the provided delay steps. ints([method]) Collect all integrators in this node and the children nodes. load_states(filename[, verbose]) Load the model states. nodes([method, level, include_self]) Collect all children nodes. register_delay(name, delay_step, delay_target) Register delay variable. register_implicit_nodes(nodes) register_implicit_vars(variables) reset(V, C_Ca, E_Ca) Reset function which reset the whole variables in the model. save_states(filename[, variables]) Save the model states. train_vars([method, level, include_self]) The shortcut for retrieving all trainable variables. unique_name([name, type_]) Get the unique name for this object. update(t, dt, V, C_Ca, E_Ca) The function to specify the updating rule. vars([method, level, include_self]) Collect all variables in this node and the children nodes.

Attributes

 global_delay_targets global_delay_vars name steps