Supplemental Figure S1. Details on the detection of movement onset, and movement
velocity, for the stop/move task. A, biceps EMG (top) and triaxial accelerometry
(bottom trace) for elbow movement task in one subject, for all 5 epochs studied. The
vertical arrows mark the timing of a button push initiated by the investigator when the
start of movement was observed. The timing of the button push was used to define a
time period (2 to 1 seconds prior to button bush) that could be used as a baseline rest
period for automated detection of movement onset. B, Detail of EMG for second
“move” epoch. The horizontal dotted lines indicate the +/- 7 standard deviations of
the baseline signal. The vertical dotted line indicates where the signal crossed this
threshold; providing the movement start time for the data shown in Figure 4. C, Detail
of accelerometry for the second “move” epoch; definitions of lines same as for B. The
timing of the accelerometry start and stop show that the duration of this “move” epoch
was 7.90 seconds, and the number of cycles in the accelerometry trace (six) are used
to calculate the angular velocity for this epoch (0.76 cycles/sec).
The angular
velocities for all five move epochs were averaged to define the angular velocity for
the elbow move task in this subject. The validity of the “automated” EMG and
accelerometry-based detection of movement onset was verified by visual inspection of
the traces, and by making sure that the detected times corresponded approximately
(within 0.5 seconds) with the times of the button push performed by the investigator
at the visually observed start and end of movement. Note that for jaw movements
EMG and accelerometry data were not available; so for these, and for some limb
move epochs where accelerometry or EMG were of low quality, the videotape of the
task was used to determine the number of movement cycles/second by counting
cycles with respect to the tape time. D, mean (+/ standard error of the mean) angular
velocities for all five types of movement, averaged for all nine subject in each group
and compared across the three disease groups. p-values are for one-way ANOVA;
there were no significant differences for any arm movement or for jaw movement,
while for foot movements, surprisingly, the Parkinson’s disease (PD) group had a
faster movement velocity than the dystonia (Dys) or essential tremor (ET) groups.
Supplementary Figure S2. Comparison of M1 log power across disease groups
during the stop phase of the stop/move task, up to the Nyquist frequency of 500 Hz.
This figure is a continuation of the M1 log power plot for the “stop” phase of the
elbow movement task (Figure 6 left column, third row), to illustrate the range over
which broadband gamma power distinguishes the Parkinson’s disease (PD) group
from the dystonia (Dys) and essential tremor (ET) groups. Solid and dotted lines
represent the mean +/- standard error of the mean, respectively, for each disease
group. Frequencies from 30 Hz to 460 Hz were divided into bands as follows: 30-55
Hz, 76-100 Hz, 136-160 Hz, 196-220 Hz, 256-280 Hz, 316-340 Hz, 376-400 Hz, and
436-460 Hz. The bands were selected to avoid harmonics of the line frequency of 60
Hz. One way ANOVA for mean log power in each frequency band, with disease as
the between subjects factor, was computed separately for each frequency band. Mean
log power for Parkinson’s disease was significantly greater than both other disease
groups up to 220 Hz. Bands showing a significant difference are indicated by yellow
bars with the ANOVA p-value are provided in the bar.
Supplemental Figure S3. Assessment of the effect of chronic benzodiazepine or
baclofen use on mean log power in the beta band during the stop/move task (elbow
joint movement). Boxplot of log power in the beta band (13-30 Hz) for the nine
dystonia subjects, seven of whom were taking oral benzodiazepines or baclofen up to
the day prior to data collection. Horizontal line=median, box=25th and 75th
percentiles, “whiskers” = range of values. Log beta power levels for the two subjects
not taking chronic benzodiazepines or baclofen are indicated with asterisks (*). None
of the points for these two patients represent “outlier” values.
Movie 1. The movie shows the elbow movement task in subject ET-4. One of the five
move epochs is shown, followed by the beginning of the subsequent stop epoch.
Surface EMG electrodes cover the deltoid, biceps, and wrist extensors. An
accelerometer (black strap) is on the forearm. The white brace on the forearm holds
an arterial line in place and is unrelated to the study.