Tag: Nicole Swann

Effect of inter-stimulus interval duration and predictability on sensorimotor beta

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.

Learning to learn: Making sense of electrophysiology data

Presenter(s): Ryan Leriche—Biology

Faculty Mentor(s): Nicole Swann

Session: Prerecorded Poster Presentation

With no previous signal processing background, I began studying how electrical brain waves vary with movement speed and uncertainty . When applying all that I read, I learned when to flesh the details or just see the big picture .

My lab uses scalp-electroencephalography (EEG) to record brain activity . EEG data can be noisy,
but there are methods to see through this noise . After some pre-processing, I ran an independent component analysis to decompose a complex signal into its sub-signals . I removed the eye movement sub-signals as I just was interested in brain activity . With kurtosis values—the sharpness of a signal—I could remove artifactual trials .

I was uncomfortable using ICA and kurtosis measures without knowing exactly how they worked . Learning every nuance would have halted my analysis progression . So, with a conceptual understanding, I used these tools from the EEGLAB Toolbox for MATLAB to generate a cleaner EEG signal .

With a clean signal, I began my time-frequency analysis . This would describe how well a sine wave at a given frequency represents my signal . I could not get a conceptual hold on this topic . After pausing my analysis and taking an online course—at my PI’s suggestion—my progress accelerated .

I now could examine how electrical brain activity changes with movement uncertainty and speed . My analysis suggests that brain activity increases with slower movements; however, now I need to learn how to statistically verify this result .

Looks like I need to continue reading methodology papers and MATLAB/EEGLAB documentation .

Electrophysiological Patterns of Skilled Motor Movements

Presenter(s): Vanessa Hufnagel—Biology

Faculty Mentor(s): Nicole Swann, Alexander Rockhill

Session 5: The Wonders of the Brain

Proposed future missions to send humans to Mars for long term exploration require the development of improved waste management technology in space and increased reliable energy for running necessary systems . In this study, the potential of methanogenic bacteria from wastewater sludge
to be a source of biomethane in the atmospheric composition of Mars was explored . Bottles of wastewater containing methanogens were prepared anaerobically and sparged with either nitrogen or a martian gas mixture and their biogas production was tracked and compared over time . Research findings proving high survivalbiltiy rates of the bacteria and high metabolic function under these extreme conditions suggest anaerobic digestion of mission waste to be a viable solution for recycling human waste and producing biomethane for the production of energy .

Comparison of Stop-Signal and Continuous Movement Reaction Stop Times to Measure Inhibitory Control

Presenter(s): Dominique Denning—Human Physiology

Faculty Mentor(s): Nicole Swann, Kelsey Schultz

Session: Prerecorded Poster Presentation

For the past few decades, a major tool used to study inhibitory control has been the Stop-Signal Task (SST) . This task gives an estimate of how well individuals can inhibit initiated movements . The speed of stopping can be estimated as the stop-signal reaction time, or SSRT . This task has proven useful, but there are limitations . For example, SSRT can only be estimated overall and not at the individual trial level . Additionally, the standard stop task involves stopping a planned movement, rather than stopping a movement which is already ongoing . To address these limitations, we have developed a new continuous movement stop task (CMST) . This task directly measures the termination of an ongoing movement, allowing measurement of stopping speed at the individual trial level . It is currently unknown how stopping measures with this new task relates to SSRT measured with the conventional stop signal task . Our research addresses this question . Thirty participants will complete both the standard stopping task and our new continuous movement stopping task . We will compare stopping speed derived from our novel task to conventional SSRTs estimated by the standard stop task . The results of our study will help us better understand the relationship between the two tasks and also help establish the generalizability of inhibitory control .