A system for measuring synchrony between two or more regions, or within a single region, of a subject's brain. The system can include a signal conditioning module in communication with a phase extraction module. The signal conditioning module can receive an oscillating signal, bandpass filter the signal, and convert the signal to its real and imaginary components. The phase extraction module can receive the real and imaginary components, determine the quadrant of the oscillating signal on the complex plane based on the real and imaginary components, and determine the phase of the oscillating signal using a linear arctangent approximation based on the determined quadrant. The system can calculate synchrony metrics based on the determined phase.