Computer-implemented methods of enabling an on-the-fly generation of at least one user-defined montage from EEG electrodes positioned in a patient's brain, on the patient's brain and/or on the patient's scalp. The methods includes generating a graphical interface to display a view of the patient's brain and/or scalp overlaid with the EEG electrodes, each of which is uniquely identified with reference to its position in the patient's brain, on the patient's brain and/or on the patient's scalp, displaying a tool within the graphical interface for selecting at least one electrode from the displayed EEG electrodes, indicating a reference electrode corresponding to the selected electrode, accessing EEG signals corresponding to the electrode and the reference electrode, and generating another graphical interface to display an EEG trace indicative of a comparison of EEG signals of the electrode and the reference electrode.