Presenter(s): Ryan Leriche
Faculty Mentor(s): Nicole Swann
Oral Session 4 CQ
It is well established that the oscillatory beta band (13-30Hz)—a range of frequencies detected from electrical brain waves—modulate in a consistent manner during motor-response tasks over the sensorimotor cortex contralateral to movement. Studies have shown a myriad of parameters (e.g. movement certainty, grip type, response speed, etc.) that cause movement related beta band spectral power decreases. Purely visual stimulus processing studies have also shown analogous beta band suppression 300-500ms post-stimulus. Delayed-go tasks (a type of motor response task) start with an initial stimulus, the “fixation cue”, that indicates an upcoming movement. A subsequent cue, the “GO cue”, tells the participant to execute the experimental movement. The inter-stimulus interval (ISI) between these two stimuli is often jittered to prevent excessive movement related beta band suppression. If jittered, the beta oscillatory changes from visual stimulus may irregularly confound the beta power surrounding movement over these sub- second ISIs. To examine this, electroencephalography (electrodes that record electrical signals from the scalp), was recorded from 11 participants in a delayed-go task with modulations to the predictability and duration of the inter-stimulus interval. Across all participants, the averaged beta power had a strong negative correlation with the length of the varied ISI condition which ranged from 300-700ms. There was also a significant difference in the per subject average of beta power based on the predictability of go-cue presentation. These data suggest that future studies need to investigate the often ignored and possibly confounding interaction of stimulus timing and movement execution on electrophysiological measures.