Difference between revisions of "User Tutorial:Configuring Online Feedback"

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(Subject-Specific Parameters)
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Start BCI2000 using the appropriate batch file at <tt>batch/CursorTask_<YourAmplifier>.bat</tt>. You might consider creating a link to this file on the desktop.
 
Start BCI2000 using the appropriate batch file at <tt>batch/CursorTask_<YourAmplifier>.bat</tt>. You might consider creating a link to this file on the desktop.
  
This CursorTask will be used to configure the BCI2000 program for this specific subject. Multiple configuration sessions are typically needed to determine the proper classifier matrix for any one subject. Properly training the program and subject for high accuracy should not be expected during the first session, nor during the first few sessions.
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This CursorTask will be used to configure the BCI2000 program for this specific subject. Multiple configuration sessions are typically needed to determine the proper classifier matrix for any one subject.
  
 
==Subject-Specific Parameters==
 
==Subject-Specific Parameters==
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**Change the ''SubjectName'' field to the subject's initials
 
**Change the ''SubjectName'' field to the subject's initials
 
**Make sure the ''SubjectSession'' field is set to <tt>001</tt> and ''SubjectRun'' is set to <tt>01</tt>
 
**Make sure the ''SubjectSession'' field is set to <tt>001</tt> and ''SubjectRun'' is set to <tt>01</tt>
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==The Spatial Filter==
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[[Image:SpatialFilter.PNG|right]]
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The Spatial Filter artificially weighs the incoming data from the electrodes based on their placement on the scalp of the subject. Because we are targeting specific areas of the brain to monitor, the spatial filter allows the program to identify when the electrode of interest is activating specifically. This is done by subtracting the average of the surrounding electrodes' data from the electrode of interest. For example, as seen to the right the output channel <tt>C3_OUT</tt> is the data from <tt>C3</tt> minus one-quarter of <tt>F3</tt>, <tt>T7</tt>, <tt>Cz</tt>, and <tt>Pz</tt>.
  
 
==The Classifier Matrix==
 
==The Classifier Matrix==
 
The Classifier Matrix applies weights to the incoming data that allows the program to accurately identify Mu Rhythm signals. This is opened by selecting '''Edit Matrix''' next to the ''Classifier'' parameter in the '''Filtering''' tab.
 
The Classifier Matrix applies weights to the incoming data that allows the program to accurately identify Mu Rhythm signals. This is opened by selecting '''Edit Matrix''' next to the ''Classifier'' parameter in the '''Filtering''' tab.
*Set ''Number of columns'' to 4, and ''Number of rows'' to 1 (or the number of features that you wish to use); then, click ''Set new matrix size'' to apply your changes.
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*Set ''Number of columns'' to 4, and ''Number of rows'' to 1. Click ''Set new matrix size'' to apply your changes.
*In the first column (of the first row), labeled ''input channel'', enter the location of the desired location, e.g. <tt>CP3</tt> for the right hand. If you did not specify electrode locations when configuring your system, enter the channel number associated with the feedback electrode.
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*In the first column (of the first row), labeled ''input channel'', enter <tt>C3_OUT</tt> if the right hand are being used, <tt>C4_OUT</tt> for the left hand, or <tt>Cz_OUT</tt> for the feet.
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*If both hands are being used, set ''Number of rows'' to 2, and click '''Set new matrix size'''. Enter <tt>C3_OUT</tt> under ''input channel'' in the first row, and <tt>C4_OUT</tt> in the second.
 
*In the second column, labeled ''input element (bin)'', enter feedback frequency in Hz, immediately followed with ''Hz'', as in <tt>12Hz</tt>.
 
*In the second column, labeled ''input element (bin)'', enter feedback frequency in Hz, immediately followed with ''Hz'', as in <tt>12Hz</tt>.
 
*In the third column, enter the value 2 corresponding to the control channel for vertical control of the cursor.
 
*In the third column, enter the value 2 corresponding to the control channel for vertical control of the cursor.
 
*In the fourth column, enter 1 as the weight. For further calibration, this weight can be increased to give stronger control or decreased to give finer control.
 
*In the fourth column, enter 1 as the weight. For further calibration, this weight can be increased to give stronger control or decreased to give finer control.
*Repeat steps 2-5 for each additional feature moving down a row each time (i.e., enter the 2nd feature on the 2nd row, etc...).
 
 
*Finally, save your configuration in a parameter file wherever you find appropriate.
 
*Finally, save your configuration in a parameter file wherever you find appropriate.
  

Revision as of 19:00, 28 January 2009

This tutorial step assumes that you have performed and analyzed an initial session. Now you are going to create a subject-specific parameter configuration for on-line feedback.

Starting up BCI2000

Start BCI2000 using the appropriate batch file at batch/CursorTask_<YourAmplifier>.bat. You might consider creating a link to this file on the desktop.

This CursorTask will be used to configure the BCI2000 program for this specific subject. Multiple configuration sessions are typically needed to determine the proper classifier matrix for any one subject.

Subject-Specific Parameters

Now, we will construct a full parameter file that is specific to that subject:

  • Begin by loading the parameter file saved previously
  • In the Storage tab:
    • Change the SourceData field to \task as opposed to \screening
    • Change the SubjectName field to the subject's initials
    • Make sure the SubjectSession field is set to 001 and SubjectRun is set to 01

The Spatial Filter

SpatialFilter.PNG

The Spatial Filter artificially weighs the incoming data from the electrodes based on their placement on the scalp of the subject. Because we are targeting specific areas of the brain to monitor, the spatial filter allows the program to identify when the electrode of interest is activating specifically. This is done by subtracting the average of the surrounding electrodes' data from the electrode of interest. For example, as seen to the right the output channel C3_OUT is the data from C3 minus one-quarter of F3, T7, Cz, and Pz.

The Classifier Matrix

The Classifier Matrix applies weights to the incoming data that allows the program to accurately identify Mu Rhythm signals. This is opened by selecting Edit Matrix next to the Classifier parameter in the Filtering tab.

  • Set Number of columns to 4, and Number of rows to 1. Click Set new matrix size to apply your changes.
  • In the first column (of the first row), labeled input channel, enter C3_OUT if the right hand are being used, C4_OUT for the left hand, or Cz_OUT for the feet.
  • If both hands are being used, set Number of rows to 2, and click Set new matrix size. Enter C3_OUT under input channel in the first row, and C4_OUT in the second.
  • In the second column, labeled input element (bin), enter feedback frequency in Hz, immediately followed with Hz, as in 12Hz.
  • In the third column, enter the value 2 corresponding to the control channel for vertical control of the cursor.
  • In the fourth column, enter 1 as the weight. For further calibration, this weight can be increased to give stronger control or decreased to give finer control.
  • Finally, save your configuration in a parameter file wherever you find appropriate.

Next Step

In the next step, you will learn how to actually perform a Mu rhythm feedback session using the configuration created in the present step.

See also

User Tutorial:Mu Rhythm BCI Tutorial, User Reference:LinearClassifier