CSIM: LifNeuronSynchan Class Reference

LifNeuronSynchan Class Reference

#include <lifneuronsynchan.h>

Inheritance diagram for LifNeuronSynchan:

List of all members.

Detailed Description

A leaky-integrate-and-fire (I&F) neuron.

Model

A standard leaky-integrate-and-fire neuron model is implemented where the membrane potential $V_m$ of a neuron is given by

$\tau_m \frac{d V_m}{dt} = -(V_m-V_{resting}) + R_m \cdot (I_{syn}(t)+I_{inject}+I_{noise})$

where $\tau_m=C_m\cdot R_m$ is the membrane time constant, $R_m$ is the membrane resistance, $I_{inject}$ is a non-specific background current and $I_{noise}$ is a Gaussion random variable with zero mean and a given variance noise.

This neuron efficiently implements 4 types of synaptic channels (NMDA, AMPA, GABA A, GABA B). plus the standard synaptic cannel. The synaptic current $I_syn$ is the sum of the 5 currents from the syn. channels. For NMDA, AMPA, GABA A, and GABA B, the synaptic conductance is increased by each synapse (see synapses) and then decays with the respective time constants $tau_{channel}$ . The current is given by $g_{channel} \cdot (E_{channel}-V_m)$ .

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 exponential 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 float getVm (void)
Returns the actual membrane voltage.

Public Attributes

float tau_nmda
The time constant for NMDA channels. [units=sec; range=(0,1000);].
float tau_ampa
The time constant for AMPA channels. [units=sec; range=(0,1000);].
float tau_gaba_a
The time constant for GABA_A channels. [units=sec; range=(0,1000);].
float tau_gaba_b
The time constant for GABA_B channels. [units=sec; range=(0,1000);].
float E_nmda
The reversal potential for NMDA channels. [units=V;].
float E_ampa
The reversal potential for AMPA channels. [units=V;].
float E_gaba_a
The reversal potential for GABA_A channels. [units=V;].
float E_gaba_b
The reversal potential for GABA_B channels. [units=V;].
float Mg_conc
Mg-concentration for voltage-dependence of NMDA-channel in [units=mMol].

Protected Attributes

double summationPoint_nmda
At this point synaptic input from NMDA-channels is summed up. [readonly].
double summationPoint_ampa
At this point synaptic input from AMPA-channels is summed up. [readonly].
double summationPoint_gaba_a
At this point synaptic input from GABA_A-channels is summed up. [readonly].
double summationPoint_gaba_b
At this point synaptic input from GABA_B-channels is summed up. [readonly].

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last modified 07/10/2006