An understanding of spike fields is critical for accurate interpretation of the EEG. We developed a computer simulation tool that takes a user-defined scalp potential distribution as input and produces the associated EEG spike-wave complex in longitudinal bipolar, transverse bipolar, and referential montages simultaneously. Users choose single or multiple foci of maximum potential on a 2-dimensional electrode map to create EEG spikes with fields of variable complexity on an organized user-adjustable background. Distances between electrodes were determined by their coordinates in 3-dimensional space, and used to calculate normalized voltages that spread according to an exponential decay function. The length-constant used for the decay function can be adjusted by the user to manipulate the scalp potential spread and size of the EEG spike field. Using this simplified model, the simulation successfully translates a scalp potential input into the expected EEG. This simulation would be useful both as a teaching tool and for interpretation of EEG spikes with complex fields.


Scalp EEG is a tool for measuring electrical activity generated within the brain. EEG serves an important role in localization of ictal and interictal sources. Localization is guided by analysis of phase reversals and fields of spikes and sharp waves. Knowledge of typical and atypical patterns of spike fields is necessary for accurate EEG interpretation. This interactive model is primarily designed as a teaching tool for aiding EEG analysis. The model does not explain source location within the brain, but instead generates predicted EEG patterns given a scalp potential distribution as input.


Electrode map. Electrode locations were based on MRI measurements [1]. Mouse clicks were mapped to a 40x28 array, overlaid on the scalp image. Heatmap colors were assigned based on normalized voltages between 0.5 and 1.

Voltage distribution. The location of a click was normalized to 1. Array values were determined according to the decay function, Vd = Vmax ⋅ e-d/λ, where distance d was calculated based on published x,y,z coordinates for the electrodes [1]. After electrode coordinates were fit to the array, linear interpolation of x,y values and weighted averages of z values were used for inter-electrode locations, thus approximating the shape of the scalp in three dimensions.

EEG plot. Values of relevant electrode locations on the array were subtracted and plotted as a spike-wave for each trace on all montages simultaneously. Slow-wave amplitudes were fixed proportional to spike amplitude. Background rhythms were generated using sine functions based on user frequency settings with randomized offsets.