Disclosed is a method for learning an artificial neural network in a synapse of an artificial intelligence system including generating, by an input neuron of the artificial intelligence system, a first input signal, generating, by the input neuron, a second input signal after a predetermined time, generating, by an output neuron of the artificial intelligence system, an output signal in response to the first input signal and the second input signal that are generated by the input neuron, and adjusting, by the synapse of the artificial intelligence system, connection strength of the artificial neural network based on a temporal order of the first input signal and the second input signal that are generated by the input neuron.