alpha-function synapse

CONICAL object class#include AlphaSyn.h
compile AlphaSyn.cpp
Base Classes
Synapseneurotransmitter-gated Channel
Derived Classes
Member Functions & Variables
real tau1 , tau2 ;
virtual void Step ( const real dt );
AlphaSyn ( VSink * pTo , VSource * pComp , real pMaxG = 0 . 1 );

This file implements a classic "alpha function" synapse. When the voltage in the presynaptic compartment (i.e., the VSource) exceeds a threshold Vthresh, the alpha function is initiated. A fixed conductance change ensues, following an exponential form specified by tau1 and tau2 (see below). The function cannot be started again until refractTime has passed.

The function actually has two forms. When tau1 == tau2, the single-exponential form is used:

G = MaxG * (t/tau1) * exp(1 - t/tau1)

where MaxG is the maximum conductance, t is time since function initiation, tau1 is the function parameter (==tau2), and G is the current conductance.

When tau1 != tau2, the double-expential form is used:

G = MaxG * ( exp(-t/tau1) - exp(-t/tau2) ) / ( tau1 - tau2 )

The alpha function is graphed below for a typical tau1 = tau2 = 0.003 (i.e., 3 ms).