Purpose: Convert the signal into power or amplitude.
Modes:
- Amplitude: The original signal without change
- Power: The signal squared:
power = signal.^2
Physiological explanation of power:
Power equals the square of amplitude. It is a measure of the “energy” of activity.
Why power is important:
- Amplitude may be positive or negative (the signal oscillates around zero).
- Power is always positive and shows the “strength” of activity.
- Power reflects overall activity better than amplitude.
Physiological meaning:
- High alpha power: strong alpha activity = strong relaxation
- High beta power: strong beta activity = strong cognitive activity
- Low power: weak activity or artifacts
Comparison of modes:
- Amplitude: Shows signal shape and the direction of change (positive/negative deflections)
- Power: Shows the intensity of activity and does not depend on sign
When to use:
- Amplitude: Signal visualization, waveform analysis, artifact detection
- Power: Quantitative activity analysis, comparison between conditions, statistics