When dealing with non-stationary objects, such as in retinal imaging where the involuntary and voluntary tremors and saccades of the eye result in a continuously moving sample, the sequential acquisition of the three images with shifted sinusoidal patterns cannot work as the desired phase shift cannot be obtained.
Results showed that the voluntary and PD tremor were essentially identical with regards to the amplitude and peak frequency.
Particular attention was given to the thalamus because it regularly presented with profound neuropathological changes in experimental scrapie of goats, which were associated with pruritus, and to the cerebellum because progressive incoordination of voluntary movements and tremor observed in experimental caprine scrapie could suggest pathological changes in these structures [ 10].
Voluntary movement arises in phase with the tremor, suggesting that the tremor may facilitate the ability to initiate movement in the face of akinesia (Hallett et al., 1977).
It is well known that EMG signals of patients with tremors contain not only voluntary commands but also involuntary tremor signals.
The voluntary signal modulates the tremor signal.
As an alternative mechanical approach, we have been developing an exoskeleton for the upper limbs to support voluntary movement in essential tremor patients (see Fig. 1a) [12 17].
However, the neural mechanisms underlying the interaction between voluntary movements and resting tremor remain unclear.
Furthermore, in many patients with Parkinson's disease, a single 'beat of tremor' preceded voluntary movements, even when there was no clinically noticeable tremor (Fig. 7).
This suggests that resting tremor and voluntary movement execution arise from similar oscillations in the motor cortex, which may explain why they do not occur simultaneously.
Periods of dyskinesia, tremor or voluntary movement detected by the examiner on visual inspection were noted and excluded from further analysis.
