NEURONS AS FUNCTION .Common nonlinear transduction description:a sigmoidal or S-shaped curve s(x) c=5.0 1.0 c=2.0 c=0.2 0 x Fig.2 s(x)is a bounded monotone-nondecreasing function of x Signal Function:S(x)= 1tea dS =cS(1-S)>0 dx (c>0) Neurons transduce an unbounded input activation x(t)at time t into a bounded output signal S(x(t))•Common nonlinear transduction description: a sigmoidal or S-shaped curve Fig.2 s(x) is a bounded monotone-nondecreasing function of x Signal Function: cx e S x − + = 1 1 ( ) ' = = cS(1− S)  0 (c  0) dx dS S Neurons transduce an unbounded input activation x(t) at time t into a bounded output signal S(x(t)). NEURONS AS FUNCTION