Figure 1.
Block diagram of the experimental setup.
Figure 2.
Placement of EMG sensors on the hand.
Figure 3.
Statistical properties of EMG signals.
(a) Average EMG intensities (EMG templates) calculated from 394 trials during which a subject wrote digit “3”. The point 1000 ms on the time axis corresponds to the initial moment of time when the pen touches the paper. (b) The mean energies of the EMG signals for 100 ms time intervals. The time interval 10 corresponds to the first 100 ms after the pen touched the paper. (c) The variation coefficients of EMG energy in each time interval.
Figure 4.
Probability plots for EMG signals.
(a) Plot of empirical cumulative distribution function (time interval 11; EMG channel 1) together with theoretical cumulative distribution function plots for normal and log-normal distributions. The confidence bounds are shown for the confidence level of 95%. (b) Probability plot for experimental data for time interval 11, channel 1 together with probability plots for theoretical normal and log-normal distributions. Axis scales are chosen to have a straight line for the theoretical probability plot with the log-normal distribution.
Figure 5.
EMG/EMG correlation functions.
(a) The cross-correlation function for EMG channels 1 and 2 (EMG1 and EMG2) as a function of two times: intervals for EMG1 and intervals for EMG2. (b) The cross-correlation function for EMG1 and EMG2 for coincident time intervals. Error bars indicate 95% confidence bounds.
Figure 6.
EMG/EMG correlation functions.
(a) EMG1/EMG1 correlation function (i.e., EMG1 auto-correlation function). (b) EMG2 auto-correlation function.
Figure 7.
Surface map of EEG electrode locations.
Figure 8.
Statistical properties of raw EEG signals.
(a) Time dependence of mean EEG energy on channel C1. (b) Variation coefficients for EEG energy on channel C1.
Figure 9.
Statistical properties of EEG signals in different spectral ranges.
Time-dependence of mean EEG energy on channel C1 in alpha (a), beta (b), and gamma (c) spectral ranges.
Figure 10.
Probability plots for EEG signals.
(a) Plot of empirical cumulative distribution function for the EEG on channel C3, time interval 10, together with the theoretical cumulative distribution function plots for normal and log-normal distributions. The confidence bounds correspond to a 95% confidence level. (b) Probability plot for experimental data together with probability plots for theoretical normal and log-normal distributions. The axis scales are chosen to make the theoretical probability plot of the log-normal distribution a straight line.
Figure 11.
Color-coded maps for the EEG/EEG correlations.
(a) Correlation coefficients between channel C3 and all other EEG channels. (b) Correlation coefficients between channel C4 and all other EEG channels.
Figure 12.
Changes in EEG/EEG correlations during the trial.
Color-coded plots show correlation coefficients between channel C1 and all other EEG channels for consecutive time intervals.
Figure 13.
Changes in EEG/EEG correlations during the trial.
Color-coded plots show correlation coefficients between channel C2 and all other EEG channels for consecutive time intervals.
Figure 14.
Time-dependent EEG/EEG correlation functions for three pairs of channels.
Error bars indicate 95% confidence bounds. (a) Channels C5 and C1 - both located over the left hemisphere. (b) Channels C1 and C2 - C1 over the left and C2 over the right hemisphere. (c) Channels C2 and C6 - both located over the right hemisphere.
Figure 15.
EEG/EEG correlation function between channels FC5 and CP6 with the maximal inter-channel spacing over the motor cortex area.
Error bars indicate 95% confidence bounds.
Figure 16.
(a) Auto-correlation function for channel C3. (b) Cross-correlation function for channels C3 and C4.
Figure 17.
EEG/EMG correlation functions.
(a) Correlation function for EMG channel 1 and EEG channel C3. (b) Correlation function for EMG channel 2 and EEG channel C4.
Figure 18.
EEG/EMG correlation functions at coincident time intervals.
The correlation functions for EEG channel C1 and EMG channels 1 (a) and 2 (b). Error bars indicate 95% confidence bounds. The values of the correlation coefficient are statistically significant if the upper and lower confidence limits have the same sign.