Advanced usage

this page presents in-depth the controls availabl through the interface on the algorithm. The algorithm itself is presented in Algorithm.

Advanced usage

Starting, loading data, defining corticalmap parameters:

The first mandatory step is to load the data. This can be done by two different ways.

• Loading a batch file (or batchFile). This is done either by using the associated button Browse and selecting the file in the assistant, or by typing the path in the dedicated field.

The batchFile is an ini-formatted file, containing rootDir, workDir, eegFile, electrodesFile, headFile and optionnally sourcesFile as keys (comments are allowed, starting by ';'). If the sources locations and moments are known they appear in View 0 (light grey cones in moments directions with normalized amplitude). View 1 (EEG) is then displayed.

• Loading data separetely. This is done by using the buttons Edit head, Edit electrodes, Edit sources. If a batchFile was loaded, these buttons are furnish the corresponding informations.

Harmonic order (optional): order of the spherical harmonic expansion, for the cortical mapping process.

Penalty (optional):

Note that all optional choices possess associated default values.

Click on Next. Views 2, 3, 4 (potential on scalp, skull, cortex) are then displayed.

Defining scan parameters (optional):

# poles: number of poles for the best quadratic rational approximation step (see Algorithm).

# Directions: number of scan directions.

# slices: number of planar cross sections (orthogonal to a given scan direction, same quantity for all directions)).

Stopping criterion: thresholding parameter.

Fourier order: number of Fourier coefficients used for the restriction of the potential to planar sections (disks, for scans).

Poles multiplicity: for the best quadratic rational approximation step.

alpha: regularization parameter, used by the scan process for its own preliminary cortical mapping steps (run again in each selected directions before 2D computations).

Click on Next. The progress bar will indicate the progresses in the scans computations.

Scans selection:

Once the scans are calculated (views 5), the user needs to select the good ones (with "watch needles" poles). The selected scans are displayed in the results sphere on the right (view 0).

Weight (optional): filter for the number of poles in the scalps views.

Error (optional): filter for the number of poles in the scalps views.

# sources: quantity of sources to be estimated.

Click on Next.

Sources estimation:

The computed sources locations and moments appear in View 0 (dark grey cones for the clustered estimated sources and black cones for the final results after dipole fitting). Their numerical values can be obtained by moving the mouse on the top white right part to make the button appear, and then clicking on "sources". Errors estimation are provided as well, if the sources are known (see Error Calculation).

Saving results:

Only the last results computed by each module may be saved (state machine)

Click on the button File on the top left blue part, then click on:

• Save to use the default parameters (all computations will be saved)
• Export to tune the results that will be saved, the location and the format of the file through a graphical interface.