Hi All

It has been suggested to me that the folks in this list might be able to
help me out of my misery.

As part of my learning curve to building a rather detailed model of a small
neurone complex I am implementing some existing models in R.

For the moment I want to implement the Izhikevich model as described in his
2003 paper. The equations are as follows:

v' = 0.04v^2 + 5v + 140 - u - I
u' = a(bv - u)
if v=30 then v<-c else u<-u+d

I don't know how to implement the if condition in my R code. I'm using
deSolve. Here is my code so far.

library(deSolve);
Izhikevich <- function(time, init, parms) {
  with(as.list(c(init, parms)),{
    dv <- (0.04*v^2)+(5*v)+140-u+I;
    du <- a*(b*v-u);
    if (v>=30) v<-c else v<-u+d;
    list( c(dv, du))
  })}
parms=c( a=0.02, b=0.2, c=-65, d=8,I=10);
times=seq(from=1, to=1000, by=1);
init=c(v=-65, u=0.2);

out<-ode(y=init, times=times, func=Izhikevich, parms=parms)
plot(out)

Can someone perhaps help me out?

Regards
Jannetta

-- 

===================================
Web site: http://www.jannetta.com
Email: jannetta@henning.org
===================================

	[[alternative HTML version deleted]]

