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CSIM: Izhi_Neuron Class Reference
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Izhi_Neuron Class Reference

#include <izhi_neuron.h>

Inheritance diagram for Izhi_Neuron:

SpikingNeuron Neuron Forceable SynapseTarget Advancable csimClass List of all members.

Detailed Description

A canonical bursting and spiking neuron.

see Izhikevich E. "Simple model of Spiking Neurons"

Model

A canonical neuron model is implemented where the membrane potential $V_m$ of a neuron is given by

, $R_m$ is the membrane resistance, $I_{syn}(t)$ is the current supplied by the synapses, $I_{inject}$ is a non-specific background current and $I_{noise}$ is a Gaussion random variable with zero mean and a given variance noise.

At time $t=0$ $V_m$ ist set to $V_{init}$ . If $V_m$ exceeds the threshold voltage $V_{thresh}$ it is reset to $V_{reset}$ and hold there for the length $T_{refract}$ of the absolute refractory period.

Implementation

The simple Euler method is used for numerical integration.

Public Member Functions

  • virtual int updateInternal (void)
    Recalculate exp. Euler constants.
  • virtual void reset (void)
    Reset the leaky I&F neuron.
  • virtual double nextstate (void)
    Calculate the new membrane voltage and check wheter Vm exceeds the threshold V_thresh.
  • virtual int isRefractory (void)
    Returns 1 (0) if the neuron is (not) in its absolute refractory period.

Public Attributes

  • float Cm
    The membrane capacity $C_m$ [range=(0,1); units=F;].
  • float Rm
    The membrane resistance $R_m$ [units=Ohm; range=(0,1e30)].
  • float Vthresh
    If $V_m$ exceeds $V_{thresh}$ a spike is emmited. [units=V; range=(-10,100);].
  • float Vresting
    The resting membrane voltage. [units=V; range=(-1,1);].
  • float Vreset
    The voltage to reset $V_m$ to after a spike. [units=V; range=(-1,1);].
  • float Vinit
    The initial condition for $V_m$ at time $t=0$ . [units=V; range=(-1,1);].
  • float Trefract
    The length of the absolute refractory period. [units=sec; range=(0,1);].
  • float Inoise
    The standard deviation of the noise to be added each integration time constant. [range=(0,1); units=A;].
  • float Iinject
    A constant current to be injected into the LIF neuron. [units=A; range=(-1,1);].
  • float a
    A constant (0.02, 01) describing the coupling of variable u to Vm;.
  • float b
    A constant controlling sensitivity og u.
  • float c
    A constant controlling reset of Vm (1000*Vreset).
  • float d
    A constant controlling reset of u.

Protected Attributes

  • double Vm
    The membrane voltage $V_m$ [readonly; units=V;].
  • double Vb
    The membrane voltage in millivolt.
  • double Vint
    The membrane voltage in millivolt.
  • double u
    internal variable
  • double ub
    The internal variable u adapted to millivolt and millisecond.
  • float Isyn
    synaptic input current

Private Attributes

  • int nStepsInRefr
    If positive then this counter tells us how many time steps we are still in the absolute refractory period.
  • double C1
    Internal constants for the exponential Euler integration of Vm.

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(C) 2003, Thomas Natschläger last modified 07/10/2006