User Tutorial:Introduction to the Mu Rhythm

Behavioral Properties

• Amplitude modulation by intended or imagined movement

Physical Properties

• Origin in the sensorimotor cortex
• Arc-shaped, periodic wave form, corresponding to a line spectrum with a strong first harmonic
• Dipolar source character, connection with cortical surface
• Typical scalp potential distributions

BCI Construction

• By imagination of movement, a human subject can wilfully influence the amplitude of her/his mu rhythm. Continuous feedback of mu rhythm amplitude can help improve this natural ability by selective reinforcement of successful strategies.
• Much like a historic AM radio receiver, a mu rhythm BCI treats the mu rhythm as a carrier signal with information impressed on it by amplitude modulation.
• BCI operation consists of
  • spatial selection (spatial filter <-> directional antenna)
  • frequency selection (classifier <-> tuning wheel)
  • carrier demodulation (spectral amplitude <-> rectifier diode)

Practical Aspects

• How to localize the motor cortex with the help of an EEG cap
• Suggested movement imagination

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