found that the premovement beta ERD was strongly lateralized when movement was cued to one side with certainty, and generally bilateral when the cue gave no directional information. They found that on the direct cue trials, beta ERD began significantly earlier, which again suggests that this response was modulated by the certainty of the motor plan. evaluated the effects of direct and ambiguous cues on the beta ERD during the planning period. They found that the beta ERD during the planning period was inversely related to the number of possible movement directions that is, with fewer directional cues, indicating greater directional certainty, the amplitude of the pre‐movement beta ERD was higher. In their task, a variable number of cues, reflecting possible movement directions, were presented prior to the signal to move. used magnetoencephalography (MEG) and a joystick‐movement task that involved differing degrees of uncertainty in movement direction. While the beta ERD has been recognized as important to movement, only recently have studies begun to characterize its unique functional role. Studies have also shown the primary and extended motor regions to be functionally connected (i.e., coherent) in a dynamic way during both continuous movement and rest, which suggests that movement execution is served by a broad, coherent sensorimotor network. Furthermore, along the precentral and postcentral gyri, this response generally follows the known somatotopic organization of these cortices (i.e., mototopy/somatotopy). This neural response has been reliably localized to regions that include the precentral and postcentral gyri, supplementary motor area, premotor areas, cerebellum, and posterior parietal areas, with many studies reporting activity in several of these regions simultaneously. Prior to movement onset there is a strong event‐related desynchronization (ERD) in the beta band (15–30 Hz) that starts 0.6–0.8 s before movement, and continues ∼0.4 s after movement. In humans, simple, transient movements (real or imagined) are associated with a well‐known pattern of oscillatory neural responses in the sensorimotor cortices. These data further suggest that execution of complex motor behavior may recruit key regions of the fronto‐parietal network, in addition to traditional sensorimotor regions.
This study is the first to demonstrate that complexity modulates the dynamics of the peri-movement beta ERD, which provides crucial new data on the functional role of this well-known oscillatory motor response. There was also an increase in functional connectivity between the left DLPFC and right parietal shortly after movement onset during complex but not simple sequences, which produced a significant conditional effect (i.e., complex > simple) that was not attributable to differences in response amplitude. We found stronger beta desynchronization during complex relative to simple sequences in the right parietal and left dorsolateral prefrontal cortex (DLPFC) during movement execution. We also examined the dynamics by imaging beta activity before and during movement execution and extracting virtual sensors from key regions.
In this study, we used magnetoencephalography (MEG) and a novel motor sequence paradigm to probe how motor plan complexity modulates peri‐movement beta oscillations, and connectivity within activated circuits. Several studies have connected this response to motor planning and/or movement selection operations, but to date such studies have examined only the early aspects of the response (i.e., before movement) and a limited number of parameters. In particular, there is a strong beta (15–30 Hz) desynchronization that begins before movement onset and continues during movement, before rebounding after movement termination. Cortical oscillatory dynamics are known to be critical for human movement, although their functional significance remains unclear.