Table 1.

Evidence for an oscillatory basis of motor control.

(1)	experiments have shown that single reaching movements have pulses of acceleration at approximately 10 Hz, indicating that single movements contain submovements [16]. Submovements can also be observed by direct recording from muscle; Brown & Cooke [17] found that electromyogram bursts do not have a continuous distribution of durations; instead, they have durations that occur in increments of 70–80 ms. A number of models attribute these submovements to intermittent control [18–20]
(2)	Gross et al. [21] found correlations between oscillations in the cerebello-thalamo-cortical loop, as detected using magnetoencephalography (MEG), and 8 Hz muscle submovements, as detected by EMG. Park et al. [22] showed that muscle oscillations at this frequency (tremor) are dependent on the inferior olive. Previous work [23] had indicated that tremor is still seen in deafferented patients and thus is a result of central drive rather than peripheral feedback
(3)	linkage of action initiation to oscillatory phenomenon is demonstrated by two lines of work. First, movement occurs at a preferential phase of baseline tremor (5–10 Hz) [24]. Second, short latency saccades are initiated at a preferential phase of 10 Hz alpha oscillations [25]
(4)	the frequency limit on single-digit movements is approximately 10 Hz, as demonstrated by the upper limit on typing speed at about 10 characters per second (http://10fastfingers.com/typing-test/english/top50)
(5)	single-unit [26] and field potentials [27,28] reveal oscillations in various frequency bands in motor cortex during actions
(6)	the psychological refractory period occurs when an individual has to complete two tasks that are separated by a certain time interval. If this time interval is too short, there is a bottleneck in performance, suggesting that some portion of processing occurs in a discrete, serial, one-after-the-other manner [29]. A model called the basic unit of motor production (BUMP) assumes three stages of processing: sensory analysis, response planning and a response execution period [18,19]. It is further assumed that the response planning stage is discrete and serial, with a duration of 100 ms. With these assumptions, their model provides justification for the intermittent hypothesis and the psychological refractory period