Abstract: A neural network comprising artificial neurons interconnected by connections, wherein each artificial neuron is configured to receive an input signal from and send an output signal to one or more of the other artificial neurons through one of the connections; each input and output signal is either positive or negative valued; and each artificial neuron has an activation at a time point, the activation being determined by at least input signals received by the artificial neuron, output signals sent by the artificial neuron, and a plurality of weights, wherein at least one weight is self-tuned at the time point. Also provided are methods of tuning neural networks.