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Figure 6 | Journal of NeuroEngineering and Rehabilitation

Figure 6

From: Brain-Computer Interface Controlled Functional Electrical Stimulation System for Ankle Movement

Figure 6

Power spectral density at electrode Cz. A broadband (8-50 Hz) desynchronization of EEG signals at electrode Cz for subject B. Red and blue traces denote the average (n = 100) power spectra of EEG signals under idling and foot dorsifiexion conditions, respectively. The shades represent ±1 SEM (standard error of mean) bounds. Black trace represents the signal-to-noise ratio (SNR), defined as in [36]: SNR( f SNR) = ( μ i ( f ) − μ d ( f ) ) 2 σ i 2 ( f ) + σ d 2 ( f ) , where f is the frequency, μi(f) and μd(f) are the average powers at the frequency f under idling and dorsifiexion conditions, respectively, and σ i 2 ( f ) and σ d 2 ( f ) are the corresponding variances. The values of SNR above the magenta line define the frequencies with statistically significant difference between μi(f) and μd(f) (p < 0.01, paired t-test).

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