This EEGLAB plugin allows the computation of measures provided by the defunct Lexicor Neurofeedback company. The MATLAB functions have been programmed to match (as close as possible) Lexicor output. As such, it is a valuable resource for Neurofeedback users. Please note that the Lexicor TDT data format is compatible with the Neuroguide TDT format. Therefore, this plugin can also replot measures computed using Neuroguide.

Thanks to Robert Lawson from EEGWorks for his assistance in the development of these tools.

Use the EEGLAB plugin manager to install the plugin (menu item File > Manage EEGLAB extensions, then search for TDT_utils).

This plugin works on continuous data (ideally pre-cleaned data). Start EEGLAB and load the eeglab_data.set file in the sample_data directory of EEGLAB.

Then, use menu item Tools > Create/plot TDT files > Compute measures for TDT text files, and the following interface will pop up.

Select Use current, which will use the current dataset. The plugin also allows to load ASC data files (text files organized in a tabular form with each column containing the data for one electrode) or EDF file. Then the following interface pops up allowing you to select measures to compute. Hold the shift key and select all measures, as shown below.

You may also load a file containing your frequency band definition. "Latency" and "Duration" indicate the onset and offset of data to be considered for processing (0 indicates to start at the beginning of the data and inf indicates to use all the data). The window size (default of 1 second) and window overlap (default of 0 seconds) used for spectral decomposition may also be changed. Press Generate Report to compute the measures. The measures are saved in a TDT file with the same name as the dataset file name. This is the same type saved by Neuroguide (although the measures computed by Neuroguide may differ).

Once the measures have been computed, they may be plotted. Use menu item Tools > Create/plot TDT files > Plot measures from TDT text files. First, the program will ask you to select a TDT file. The TDT file is being saved in the same folder as the data so it may not be in the current folder. After selecting the TDT file, the following interface will pop up.

Select the first 10 values, and press the ">>" button, then select the Cool colormap and press the Generate plot button. The following graphics will pop up. Note that the file will automatically be saved to disk.

Now, call back menu item Tools > Create/plot TDT files > Plot measures from TDT text files and select the first 10 frequencies as well as a 0.95 threshold.

The following plot will pop up. Note that the scale on top might not reflect actual coherence values.

Some of the plots below may require calling the plotting functions from the command line to use options not available in the menus.

• test_lexicor_power.m - this compares the output of Lexicor software for power analysis with the output of the MATLAB function in this repository. The correspondence is almost perfect (meaning the ratio is close to 1).

FFT absolute power (LEX amplitude)
Delta ratio: 0.96 (+-0.01)
Theta ratio: 1.01 (+-0.01)
Alpha1 ratio: 1.00 (+-0.00)
Beta1 ratio: 1.00 (+-0.00)
Beta2 ratio: 1.00 (+-0.00)

FFT relative power (LEX relative power)
Delta ratio: 0.96 (+-0.01)
Theta ratio: 1.00 (+-0.01)
Alpha1 ratio: 1.00 (+-0.01)
Beta1 ratio: 1.00 (+-0.01)
Beta2 ratio: 1.00 (+-0.01)

LEX peak frequency
Delta ratio: 1.18 (+-0.10)
Theta ratio: 0.96 (+-0.01)
Alpha1 ratio: 1.00 (+-0.00)
Beta1 ratio: 1.00 (+-0.00)
Beta2 ratio: 1.00 (+-0.00)

LEX peak amplitude
Delta ratio: 0.94 (+-0.02)
Theta ratio: 1.01 (+-0.01)
Alpha1 ratio: 1.00 (+-0.00)
Beta1 ratio: 1.00 (+-0.00)
Beta2 ratio: 1.00 (+-0.00)

• test_lexicor_phase.m - this compares the output of Lexicor software for phase analysis with the output of the MATLAB function in this repository. Note that the correspondence is not perfect although it is still quite good.

Theta freq.
Nb values inferior in lex:99
Nb values superior in lex:72
Absolute difference:0.16 +- 0.15

Alpha freq.
Nb values inferior in lex:67
Nb values superior in lex:104
Absolute difference:0.17 +- 0.14

v1.3 - Increase neuroguide compatibility. Fix the issue with plotting spectral power (array was transposed). Add documentation.

v1.2 - Adding documentation and fileout option to tdtreport.m

v1.1 - Fix window size issue when computing spectral decomposition

v1.0 - Initial release