//SLUGens released under the GNU GPL as extensions for SuperCollider 3, by Nick Collins, http://composerprogrammer.com/index.html

FitzHughNagumo Neuron Firing Model Oscillator

FitzHughNagumo.ar(reset, rateu, ratew, b0, b1, initu, initw, mul, add)

Naive Euler ODE solver implementation of the FitzHugh-Nagumo neuronal 2-dimensional model for oscillatory firing.  

du/dt= rateu*(u-0.3333*u^3 - w)

dw/dt= ratew*(b0+b1*u - w)

All inputs can have .kr rate UGens plugged in.

reset- input

rateu- update rate for u

ratew- update rate for w 

b0- equation constant

b1- equation constant

initu- reset value for u

initw- reset value for w

//Can be very noisy, high pitched and aliases badly- ie great fun, but watch out for your ears, filter, try out odd param settings. I've turned all the amplitudes down in the following

//defaults, high pitched! WARNING

{Out.ar(0,Pan2.ar(0.05*FitzHughNagumo.ar(0,0.01,0.01,1,1),0.0))}.play

//updates too fast, nice noise

{Out.ar(0,Pan2.ar(0.02*FitzHughNagumo.ar(0,1,1,1,1),0.0))}.play

//modulate constants to mess with noise

{Out.ar(0,Pan2.ar(0.01*FitzHughNagumo.ar(0,1,1,LFNoise0.kr(1,0.48,0.5),LFNoise0.kr(1,0.9,1)),0.0))}.play

//retrigger

{Out.ar(0,Pan2.ar(0.1*FitzHughNagumo.ar(Impulse.kr(10),0.0001,0.001,1,0.000001,LFNoise0.kr(10),LFNoise0.kr(10)),0.0))}.play

//more retriggering with mouse exploration 

{Out.ar(0,Pan2.ar(0.05*FitzHughNagumo.ar(Impulse.kr(10),MouseX.kr(0.0001,0.1,'exponential'),MouseY.kr(0.0001,0.1,'exponential'),0.5,0.1,LFNoise0.kr(10,0.3),LFNoise0.kr(10,0.2)),0.0))}.play

//right of the screen is most amusing

{Out.ar(0,Pan2.ar(0.1*FitzHughNagumo.ar(Impulse.kr(100),MouseX.kr(0.0001,1,'exponential'),MouseY.kr(0.0001,1,'exponential'),0.5,0.1,SinOsc.kr(10,0,0.3),SinOsc.kr(10,0,0.8)),0.0))}.play

//explore

(

{Out.ar(0,Pan2.ar(

CombN.ar(

Resonz.ar(FitzHughNagumo.ar(Impulse.kr(LFNoise1.kr(1,10,50)),MouseX.kr(0.0001,100,'exponential'),MouseY.kr(0.0001,1,'exponential'),MouseY.kr(0.1,3),MouseX.kr(0.1,3),SinOsc.kr(20,0,0.7),SinOsc.kr(21,0,0.8)),LFNoise1.kr(LFNoise1.kr(0.2,0.05,0.07),400,600),0.1),

0.05,0.05,2

)

,0.0))}.play

)

//surprise! (wait for it)

(

SynthDef("FHN-surprise",{Out.ar(0,Pan2.ar(

CombN.ar(RLPF.ar(FitzHughNagumo.ar(0,0.00001,0.00001, mul:0.1),1000,0.01),0.1,0.1,10)

,0.0))

}).play

)

//controlled surprise

(

SynthDef("FHN-surprise",{Out.ar(0,Pan2.ar(

CombN.ar(RLPF.ar(FitzHughNagumo.ar(0,0.00001,MouseY.kr(0.00001,1,'exponential'),1, mul:0.1),1000,0.01),0.1,0.1,10)

,0.0))

}).play

)

//feedback pair

(

SynthDef("FHN-surprise",{

var fn1, fn2, retrigger;

retrigger= Impulse.kr(15);

fn1= MouseX.kr(0.0,1.0)*FitzHughNagumo.ar(retrigger,0.001,0.001,LocalIn.ar(1),1);

fn2= MouseY.kr(0.0,1.0)*FitzHughNagumo.ar(retrigger,0.001,0.001,fn1,1);

LocalOut.ar(fn2);

Out.ar(0,Pan2.ar((fn1+fn2),0.0))

}).play

)