1. A method for generating neural adaptive behavior, comprising: receiving one or more input stimuli; processing the received input stimuli to generate an output signal, wherein the processing is modulated with a first neuromodulation signal generated by a gain control unit; and controlling the gain control unit to switch between at least two different neural activity modes, wherein at least one of a level or timing of the first neuromodulation signal generated by the gain control unit is determined based on the neural activity modes.