Introduction to Laplacian montages.

Digital EEG systems allow for the creation of specialized montages not commonly available previously with analog equipment. Montages that employ the principles of local average reference techniques utilize a subset of spatially separated electrodes to produce a synthetic reference that will aid in localization. By employing these techniques, focal discharges can be visually enhanced and properly localized. The Laplacian transform is an example of a local average reference and the principles and construction of this montage are described here in brief detail. Though the montage is not suited for all situations, integration into existing lab protocols will enable technologists to provide alternative views when required in ambiguous and difficult to interpret recordings.