Results

Behavioural data

All subjects were able to perform the task without difficulty. When the frequency ratio (FR) of the higher frequency to lower frequency of the pressure generated by the subject was computed, and this tended to correlate well with UPDRS bradykinesia scores but did not reach significance (r = 0.597 p < 0.15).

Bradykinesia
Fig. 4. Comparison between amplitude of peak in alpha range of Left motor cortex component and UPDRS bradykinesia scores in the ' ' off'' state
Fig. 5. In 6/7 PD subjects, a component was derived from leads over the left motor cortex. Some of these demonstrated peaks in the alpha range, which correlated with the extent of bradykinesia

EEG/IMF coupling

Some components loaded heavily over the left primary motor cortex, and had prominent peaks in their frequency spectra at about 10 Hz (Fig. 5). The peak in their frequency spectra in the alpha range correlated with their UPDRS scores (R = 0.827, p<0.02, Fig. 4). In one subject, with prominent tremor, there was a peak at 5 Hz, exactly half of their other peak in the alpha band. Other components were in the midline and ap peared to be modulated by the expectation of pressing the button, but not the button press itself (Fig. 6). Still others (not shown) were modulated with the periods of 8 and 11 Hz, the periods that the subjects pressed.

After L-Dopa, the effect on their behavioural performance (as measured by their FR described above) was erratic. The effects on the 10 Hz peak (not shown) were less consistent.

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Post-button press

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VIAs

Fig. 6. An example of an ICA component derived from the augmented EEG/EMG data set from a single normal subject. Note that this component was continually active during the ''dual'' task (as suggested by the higher amplitudes at ^10 Hz), but was not modulated by the button press itself, possibly reflecting an attentional phenomenon from the cingulate gyrus

Fig. 6. An example of an ICA component derived from the augmented EEG/EMG data set from a single normal subject. Note that this component was continually active during the ''dual'' task (as suggested by the higher amplitudes at ^10 Hz), but was not modulated by the button press itself, possibly reflecting an attentional phenomenon from the cingulate gyrus

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