A system includes a display, sensor, and a processor. The display is configured to provide a controlled light stimulus. The sensor has an electrode configured for coupling to tissue. The sensor is configured to generate an output signal corresponding to an electroretinogram based on light evoked activity associated with glutamatergic synaptic processing. The light evoked activity is in response to an image on the display. The processor is coupled to the sensor and is coupled to the display. The processor is configured to classify a neurological condition associated with the tissue. The classification is based on the output signal.
