Doctor of Philosophy, University of Toronto (2018)
Vinod Menon, Postdoctoral Faculty Sponsor
- Event‐related deep brain stimulation of the subthalamic nucleus affects conflict processing Annals of Neurology 2018
Modulation of cognitive cerebello-cerebral functional connectivity by lateral cerebellar continuous theta burst stimulation
2017; 158: 48–57
Network connectivity measured with resting state functional magnetic resonance imaging (rsfMRI) has revealed the contribution of distinct cerebellar lobules to an array of brain wide networks sub-serving motor and cognitive processes. As distinct cerebellar lobules form relatively accessible nodes of different brain networks, this raises the possibility for site-specific modulation of network connectivity using non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS). Continuous theta burst transcranial magnetic stimulation (cTBS) induces long-lasting inhibition of cortical areas. Although previous studies have shown that cTBS of the lateral cerebellum modulates motor cortical excitability and improves symptoms in several movement disorders, the effect on cognitive domains has not been examined. We explored the immediate effects of cTBS in a sham-controlled study on the strength of intrinsic functional connectivity between cerebellar and cortical motor and cognitive regions in 12 participants. Lateral cerebellar cTBS significantly decreased functional connectivity with frontal and parietal cognitive regions, while connectivity with motor regions remained unaltered. Sham stimulation had no effect on either motor or cognitive connectivity. These results show that inhibitory cerebellar stimulation reduces intrinsic functional connectivity between different cortical areas, in keeping with the known connectivity pattern of the cerebellum. The results highlight the plasticity of cerebello-cerebral networks and indicate for the first time that this functional connectivity can be downregulated using an inhibitory neurostimulation paradigm. This may shed light on the pathophysiology of network dysfunction and is a potential treatment for cognitive and movement disorders.
View details for DOI 10.1016/j.neuroimage.2017.06.048
View details for Web of Science ID 000411450600006
View details for PubMedID 28669908
Beat-induced fluctuations in auditory cortical beta-band activity: using EEG to measure age-related changes
FRONTIERS IN PSYCHOLOGY
People readily extract regularity in rhythmic auditory patterns, enabling prediction of the onset of the next beat. Recent magnetoencephalography (MEG) research suggests that such prediction is reflected by the entrainment of oscillatory networks in the brain to the tempo of the sequence. In particular, induced beta-band oscillatory activity from auditory cortex decreases after each beat onset and rebounds prior to the onset of the next beat across tempi in a predictive manner. The objective of the present study was to examine the development of such oscillatory activity by comparing electroencephalography (EEG) measures of beta-band fluctuations in 7-year-old children to adults. EEG was recorded while participants listened passively to isochronous tone sequences at three tempi (390, 585, and 780 ms for onset-to-onset interval). In adults, induced power in the high beta-band (20-25 Hz) decreased after each tone onset and rebounded prior to the onset of the next tone across tempo conditions, consistent with MEG findings. In children, a similar pattern was measured in the two slower tempo conditions, but was weaker in the fastest condition. The results indicate that the beta-band timing network works similarly in children, although there are age-related changes in consistency and the tempo range over which it operates.
View details for DOI 10.3389/fpsyg.2014.00742
View details for Web of Science ID 000339007800001
View details for PubMedCentralID PMC4093753