Creating and editing a new EEG montage - Brain Vision Analyzer

Friday, 23 de April de 2021
Creating and editing a new EEG montage - Brain Vision Analyzer

Montages enable channels to be reconnected on a software basis or new voltage reference points to be assigned to the channels.

Montages allow you to optimize the display of data by, for example, grouping together frontal electrodes in one montage and occipital electrodes in another. When one of these montages is selected, only those channels that have been assigned to it are displayed. The sequence of channels can also be changed in a montage so that channels which were originally apart can be shown next to each other. A channel can also occur more than once in a montage.

Another useful characteristic of montages is that certain display parameters, such as the position and size of a channel, can be saved in a head view and then be called up again in a subsequent working session.

Montages are used for visualization purposes only, i.e. the resulting data only exists temporarily and the original data is not changed.

Creating and editing a new montage

To create a montage on Analyzer, open the Display tab in the ribbon and choose Create Montage. This opens the Create New Montage dialog box. 

Under Choose Reference, you choose the reference type to be used in the new montage. The following options are available for this:

Original: No new reference is calculated. This type of montage is only used to group channels together or optimize their presentation.

Average: The average reference is calculated, i.e. the average of all selected channels is used as the reference.

Laplacian: Source derivation, as described by Hjorth, is carried out. This is a method derived from the Laplace transform in which the reference is calculated from multiple neighboring electrodes of a channel.

Bipolar: Differences between channels are formed.

Once you have selected the reference type, click OK. The montage editor appears. The montage editor has the same basic functions for all four reference types. A number of additional controls are displayed for the "Laplacian" and "Bipolar" reference types.

The montage editor contains the Head View and List View tabs. These tabs allow you to select the channels contained in the montage. The head view gives you an overview of the arrangement of the channels on the head. The list view function allows you to enter new channels not displayed in the head view. You can additionally activate a grid display of the montage.

The head view shows you the position of the channels on the head.

Channels whose position is not known are displayed to the left of the head. If you click the name of a channel, it is added to the montage. If you click it again, it is removed from the montage. Channels added to the montage are highlighted in black.

Insert current channels allows you to add all the existing channels to the montage. Remove All removes all channels from the montage.

The list view displays the list of channels in the order in which they appear in the montage. You can select multiple rows in the list and delete them. In the last row, you can add new channels by choosing them from the drop-down lists or by entering them directly.

If you have entered a channel name manually then this name is added to the drop-down lists.

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Reference / original

BrainVision Analyzer Software User manual,  Software version 2.2.1, Brain Products GmbH, Zeppelinstrasse 7, 82205 Gilching, Germany, 21. August 2020, Document version 002 (2.2.1 release).

The content published here is the exclusive responsibility of the authors.

Autor:

César Noronha

Guru

cesarnoronha@brainsupport.co