running parallel loop until a variable or event

Hi guys, I'm trying to make a button blink every time just when a varriable or event change:

function blink(hObject, eventdata, parent_GUI)
 handles = guidata(parent_GUI);
 parfor i=1:3
     if get(handles.boton_circulo_visible_in,'Value')==0
         i=i-1;
     end
    set(handles.CONECTAR,'ForegroundColor',[1,1,1]);
    disp('prendido')
    pause(0.5)
    set(handles.CONECTAR,'ForegroundColor',[0,0,0]);
    disp('apagado')
    pause(0.5)
 end   

I tried with parfor loop but it say show me an error " changing the loop index is invalid inside a parfor loop iteration". So i loop up abaout other parallel loop like spmd, but also it executes only single time. I dont know what can i do to make that iterative until a variable change

Thanks