Source code for brainpy.dyn.synouts.ions

# -*- coding: utf-8 -*-

from typing import Union, Callable, Optional

import brainpy.math as bm
from brainpy.dyn.base import SynOut
from brainpy.initialize import parameter, Initializer
from brainpy.types import Array

__all__ = [
  'MgBlock',
]


[docs]class MgBlock(SynOut): r"""Synaptic output based on Magnesium blocking. Given the synaptic conductance, the model output the post-synaptic current with .. math:: I_{syn}(t) = g_{\mathrm{syn}}(t) (E - V(t)) g_{\infty}(V,[{Mg}^{2+}]_{o}) where The fraction of channels :math:`g_{\infty}` that are not blocked by magnesium can be fitted to .. math:: g_{\infty}(V,[{Mg}^{2+}]_{o}) = (1+{e}^{-\alpha V} \frac{[{Mg}^{2+}]_{o}} {\beta})^{-1} Here :math:`[{Mg}^{2+}]_{o}` is the extracellular magnesium concentration. Parameters ---------- E: float, JaxArray, ndarray, callable, Initializer The reversal potential for the synaptic current. [mV] alpha: float, JaxArray, ndarray Binding constant. Default 0.062 beta: float, JaxArray, ndarray, callable, Initializer Unbinding constant. Default 3.57 cc_Mg: float, JaxArray, ndarray, callable, Initializer Concentration of Magnesium ion. Default 1.2 [mM]. name: str The model name. """
[docs] def __init__( self, E: Union[float, Array, Callable, Initializer] = 0., cc_Mg: Union[float, Array, Callable, Initializer] = 1.2, alpha: Union[float, Array, Callable, Initializer] = 0.062, beta: Union[float, Array, Callable, Initializer] = 3.57, target_var: Optional[Union[str, bm.Variable]] = 'input', membrane_var: Union[str, bm.Variable] = 'V', name: str = None, ): super(MgBlock, self).__init__(name=name, target_var=target_var) self._E = E self._cc_Mg = cc_Mg self._alpha = alpha self._beta = beta self._target_var = target_var self._membrane_var = membrane_var
def register_master(self, master): super(MgBlock, self).register_master(master) self.E = parameter(self._E, self.master.post.num, allow_none=False) self.cc_Mg = parameter(self._cc_Mg, self.master.post.num, allow_none=False) self.alpha = parameter(self._alpha, self.master.post.num, allow_none=False) self.beta = parameter(self._beta, self.master.post.num, allow_none=False) if isinstance(self._membrane_var, str): if not hasattr(self.master.post, self._membrane_var): raise KeyError(f'Post-synaptic group does not have membrane variable: {self._membrane_var}') self.membrane_var = getattr(self.master.post, self._membrane_var) elif isinstance(self._membrane_var, bm.Variable): self.membrane_var = self._membrane_var else: raise TypeError('"membrane_var" must be instance of string or Variable. ' f'But we got {type(self._membrane_var)}') def filter(self, g): V = self.membrane_var.value I = g * (self.E - V) / (1 + self.cc_Mg / self.beta * bm.exp(-self.alpha * V)) return super(MgBlock, self).filter(I) def clone(self): return MgBlock(E=self._E, cc_Mg=self._cc_Mg, alpha=self._alpha, beta=self._beta, target_var=self._target_var, membrane_var=self._membrane_var)