| dc.description.abstract | Purpose: To assess the nature and reliability of the effects of intermittent theta burst stimulation (iTBS) vs continuous TBS (cTBS) vs sham stimulation on resting-state EEG oscillatory power in various frequency bands, determine the relationship between rTMS effects on resting-state EEG power and TMS EMG motor-evoked potentials (MEPs), and determine whether baseline neuropsychological task performance on motor and memory tasks is related to TBS plasticity at primary motor cortex (M1).
Methods: We worked with 24 healthy subjects who underwent cognitive testing at a baseline visit. These subjects would each return for three visits of TBS (where they were randomized to receive cTBS, iTBS, and Sham TBS in different orders). During each visit, corticospinal excitability was also measured through the elicitation of MEPs. Resting-state EEG was recorded before TBS administration and 15 minutes afterward. After the first three visits, subjects returned for an additional three visits in the same order as the first visits, for a total of six TBS visits. Data collected were analyzed for power in the left and bilateral frontocentral regions in the alpha and beta bands. Data were evaluated for relationships between pre/post-TBS resting-state EEG power change and cognitive testing, pre/post-TBS MEP amplitude change, and stimulation type. Pre/post EEG power changes of matched visits (e.g. cTBS visit 1 and cTBS visit 2) over the left and bilateral frontocentral regions in the alpha and beta frequencies were evaluated for test-retest reliability using Cronbach’s alpha.
Results: ANCOVAs run on the acquired data did not reveal any significant relationships between stimulation type and EEG power difference scores. Internal energy (reaction time controlled for error) of the Face Memory test was modestly correlated (~0.4) with EEG power difference scores in the cTBS condition in the beta band, and MEP amplitude change had a similar correlation to EEG power difference scores in the iTBS condition in the alpha band. Sham stimulation exhibited some test-retest reliability relative to EEG power difference scores, but iTBS and cTBS did not.
Conclusion: Cognitive and motor testing may help to predict effects of TBS on brain activity, but highly predictive factors remain elusive. It is possible that other factors may exhibit a stronger link, and this analysis may benefit from linking with evaluation of TMS-EEG, rather than resting-state EEG alone. | |
