3D head view Butterfly View Grid View & head view - Brain Vision Analyzer

Friday, 09 de April de 2021
3D head view  Butterfly View Grid View & head view - Brain Vision Analyzer

EEG views are Analyzer program components that are used to display EEG data. When you open a data set in the main window, this generates an EEG view that prepares the data and displays it on the screen. The employed view determines all aspects of the display from the arrangement of the channels in the window through to details such as the font used for the channel names.

3D head view

You can use the 3D Head View instead of the Mapping View. The 3D Head View projects the map onto a three-dimensional model of a head.

The possible settings for the 3D Head View are the same as for the Mapping View. In addition, you can rotate the head as you require. To do this, position the mouse over the head, hold down the left mouse button, and move the mouse pointer. The head rotates.

To change the size of the heads, click in the view and move the mouse wheel up and down.

In the view settings of the 3D Head View, you can also select the head displayed from several head definitions.

At the lower border of the 3D Head View there is a scale that applies to all the displayed heads. If you have chosen manual scaling of the view in the view settings then you can set the end points of the scale directly with the mouse. 

You can also grab and drag an end point of the scale with the mouse. The current position of the end point is then displayed in small characters next to the scale.

Butterfly View

The Butterfly View displays all the EEG channels overlaid over each other and allows you, for example, to visualize peaks after averaging. This makes it easy to identify the places at which there is activity in the EEG.

The channel names are listed in the upper part of the view.

If you move the mouse pointer over a channel graph, it is highlighted in orange. At the same time, a small box appears around the channel name at the top of the view to indicate which channel is currently under the mouse pointer.

Channel Pairs View and Band Channel Pairs View

The Channel Pairs View and the Band Channel Pairs View consist of two-dimensional connectivity graphs defined on the head surface. A connectivity graph comprises a network of nodes (electrodes) and edges (straight lines) connecting the nodes. Edges represent the functional coupling between two brain areas or electrodes, resp. a channel pair. 

While the Channel Pairs View can be used for both time and frequency domain data, the Band Channel Pairs View can be used for frequency domain data only. Functional coupling can be estimated in Analyzer 2 with the Coherence transform.

Similar to topographic maps, valid channel coordinates of both electrodes are required for each pair in order to generate the connectivity graphs. If the 10-10 or 10-20 electrode system is used when recording the EEG, the correct coordinates are assigned automatically. 

If other channel names are used, the Edit Channels transform can be applied to define the correct coordinates. For detailed information on editing channel properties

Use the view settings in order to configure the display of both views as well as to modify the used methods and algorithms.

The Band Channel Pairs View is not related to an equidistant subdivision of the full frequency range in equal intervals but to the specified frequency bands. The displayed data corresponds by default to the mean value within each frequency band.

The number of displayed connectivity graphs corresponds to the amount of frequency bands. You can define the frequency bands under Bands in the view settings. For detailed information on the configuration of the frequency bands.

Grid View

The Grid View arranges the channels in a grid (see Figure 4-14). The display of the EEG in the Grid View depends on the montage selected. In the case of the standard montage, the channels of the data set are distributed automatically to the rows and columns of the grid. In userdefined montages, you can specify which channels are to appear in which grid cells or which grid cells are to remain free.

The Grid View also allows you to drag cells from different channels on top of one another with the mouse to create overlays.

To do this, you can get hold of the channels by clicking the channel name or a point in the corresponding grid cell that is sufficiently far away from the graph. If you are able to grab the channel, the mouse pointer will take the form of a hand or an arrow depending on the position in the cell. 

 When you have created an overlay, the Clear Overlays button is added to the view. You can use this button to remove the overlays again. You can also combine the overlaid channels with complete data set overlays as you wish.


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César Noronha