Systems and methods are provided for determining optimized settings for a closed-loop stimulation system based on analyzing a phase response curve measured from electrophysiological activity, such as electrical nerve activity or electrical muscle activity. The slope of the phase response curve is computed and used to determine a phase window during which phasic burst stimulation should be provided to achieve a desired effect on oscillations in the subject. When the slope of the phase response curve is positive, a phasic burst stimulation applied during the phase window will decrease synchrony of the oscillations. When the slope of the phase response curve is negative, a phasic burst stimulation applied during the phase window will increase synchrony of the oscillations.