EEG Theta/Beta Ratio Calculations Differ Between Various EEG Neurofeedback and Assessment Software Packages: Clinical...

Area of Science:

• Neuroscience
• Quantitative Electroencephalography (QEEG)
• Biomedical Engineering

Background:

• The theta/beta power ratio (TBR) is associated with ADHD, often assumed equivalent across systems.
• A fixed TBR cutoff was used in the International Collaborative ADHD Neurofeedback (ICAN) trial.
• Discrepancies in TBR calculations between assessment and treatment software were observed.

Purpose of the Study:

• To investigate the reasons for differing TBR values between EEG software systems.
• To explain and compare various computational methods for calculating EEG values, including TBR.
• To highlight the importance of understanding algorithmic differences in QEEG analysis.

Main Methods:

• Comparison of computational methods for calculating TBR.
• Analysis of variance sources: spectral leakage handling and power calculation (averaging then squaring vs. squaring then averaging).
• Explanation of how different algorithms yield non-equivalent TBR values.

Main Results:

• TBR values are not equivalent across different hardware and software systems.
• Two primary sources of variance identified: spectral leakage handling and the order of operations in power calculation.
• The method of squaring voltages before averaging leads to higher band power values.

Conclusions:

• Biofeedback practitioners must be aware of the specific algorithms used by their systems for TBR calculation.
• Normative comparison data must be collected using the same system and algorithms for accurate interpretation.
• Algorithmic differences necessitate caution when comparing TBR values across studies or systems.