1. A non-linear circuit for use in a chaotic neuron circuit comprising: a first variable resistor having a first end and a second end, the first end for receiving an input signal; an amplifier having an inverting input, a non-inverting input and an output, the inverting input being connected to the second end of said first variable resistor and the non-inverting input being connected to ground; a second variable resistor having a first end and a second end, the first end being connected to the inverting input of said amplifier; a third variable resistor having a first end and a second end, the first end being connected to the output of said amplifier and the second end being connected to the second end of said second variable resistor; and a fourth variable resistor having a first end and a second end, the first end for receiving the input signal and the second end being connected to the second end of said third variable resistor.