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Kathryn Hamilton

1) How does MEG represent neuronal activity? It is very slow…
2) Who performed the MEG recordings, MRI analysis, stats, etc?
3) How do you justify using t-tests after RM ANOVA?
4) Last sentence: How might this “advance in understanding…” prove clinical useful in the future?

Nathan Glassy

While EEG records electrical activity outside of neurons, MEG records magnetic fields produced by electrical currents inside neurons. Both of which occur on millisecond timescales and is preferable for observing neuronal activity compared to Magnetic Resonance Imaging which records data on multiple second timescales.

MEG also has the advantage of providing more accurate spatial information for oscillatory activity. The oscillatory activity recorded is thought to reflect modulation of neuronal excitability in synchronously active neural assemblies.

Leighton Hinkley contributed to the methodology, software, and analysis at the Department of Radiology and Biomedical Imaging at the University of California, San Francisco. Elizabeth Dressler and Kimberley Russo also contributed to the data analysis.

We wanted to assess significance both within-group (one-sample t-test) and between control and PD groups (unpaired t-tests).

Improving our understanding brain network reorganization is clinically relevant when considering therapeutic interventions like deep brain stimulation. Previous DBS studies have found that alpha and beta-band activity in the sub-thalamic nucleus could be normalized in early PD patients. Previous studies have also been unclear as to whether the event-related oscillatory power amplitude was affected by dopamine replacement therapy. Our study contributes to this since all of our patients were on DRT at the time of scanning.

Nathan Glassy

Just to follow up on the clinical relevance, this would also be helpful in monitoring disease progression. Previous genomics / MRI studies have found that healthy PARKIN and LRRK2 carriers also had altered functional connectivity despite similar task performance as healthy non-carriers. Identifying abnormal cortical oscillatory power, latency, and frequency would be beneficial for possibly identifying subgroups of patients who have sub-acute clinical symptoms of PD.

Kevin Murnane

This is great. Really nice work. Can you give a brief overview of the main takeway for the lay community?

Elizabeth Disbrow

Check out cognitive and motor switching poster. It is fMRI data but a similar (and more complicated ) task.

Jennifer Cale

Very interesting experiment! We had related findings. We found that RTs among PD patients were significantly longer than in controls, but their accuracy was only marginally lower. This seems to support your idea that quicker reaction times resulted in lower accuracy.

Nathan Glassy

That is interesting. In general, our PD patients made more errors than controls. So there is also the possibility that they shifted their response strategy, since the cue/targets occurred roughly 1 per second. They might be trying to maintain pace and that shift in approach may underly the altered neural activity we observed.