P69. Does theta burst stimulation on visual cortex only modulate phosphene threshold after high visual demand?

Background: Continuous theta burst stimulation (cTBS) is a powerful form of repetitive transcranial magnetic stimulation capable of suppressing cortical excitability for up to 50 minutes. A growing number of studies have applied cTBS to the visual cortex in human subjects to investigate the neural dynamics of visual processing, but few studies have specifically examined its effects on central vision, which has crucial implications for safety and inference on downstream cognitive effects. Objective: Assess the safety of offline, neuronavigated cTBS to V2 by examining its effects on central vision performance on a computerized stimulus detection task. Methods: In a single-blind, randomized sham-controlled, crossover study, 17 healthy adults received cTBS and sham to V2 two weeks apart. Their central vision (≤8°) was tested at 1-minute (T1) and again at 50-minutes (T50) post-stimulation. Effects of condition (cTBS vs. sham) and time (T1 vs. T50) on accuracy and reaction time were examined using Bayes factor. Results: Bayes factor results suggested that cTBS did not impair stimulus detection over the entire central visual field nor subfields at T1 or T50. Conclusions: Our results offer the first explicit evidence supporting that cTBS applied to V2 does not create blind spots in the central visual field in humans. Any subtler changes to vision and downstream visual perception should be investigated in future studies.

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Effects of theta burst stimulation protocols on phosphene threshold

Clinical Neurophysiology ◽

10.1016/j.clinph.2006.03.019 ◽

2006 ◽

Vol 117 (8) ◽

pp. 1808-1813 ◽

Cited By ~ 69

Author(s):

Michele Franca ◽

Giacomo Koch ◽

Hitoshi Mochizuki ◽

Ying-Zu Huang ◽

John C. Rothwell

Keyword(s):

Theta Burst Stimulation ◽

Burst Stimulation ◽

Phosphene Threshold ◽

Theta Burst

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Intermittent Theta Burst Stimulation to the Primary Motor Cortex Reduces Cortical Inhibition: A TMS-EEG Study

Brain Sciences ◽

10.3390/brainsci11091114 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1114

Author(s):

Zhongfei Bai ◽

Jiaqi Zhang ◽

Kenneth N. K. Fong

Keyword(s):

Visual Cortex ◽

Motor Cortex ◽

Primary Visual Cortex ◽

Primary Motor Cortex ◽

Supplementary Motor Area ◽

Motor Area ◽

Cortical Inhibition ◽

Theta Burst Stimulation ◽

Burst Stimulation ◽

Theta Burst

Introduction: The aim of this study was to reveal the effects of intermittent theta burst stimulation (iTBS) in modulating cortical networks using transcranial magnetic stimulation and electroencephalography (TMS-EEG) recording. Methods: Eighteen young adults participated in our study and received iTBS to the primary motor cortex (M1), supplementary motor area, and the primary visual cortex in three separate sessions. A finger tapping task and ipsilateral single-pulse TMS-EEG recording for the M1 were administrated before and after iTBS in each session. The effects of iTBS in motor performance and TMS-evoked potentials (TEPs) were investigated. Results: The results showed that iTBS to the M1, but not supplementary motor area or the primary visual cortex, significantly reduced the N100 amplitude of M1 TEPs in bilateral hemispheres (p = 0.019), with a more prominent effect in the contralateral hemisphere than in the stimulated hemisphere. Moreover, only iTBS to the M1 decreased global mean field power (corrected ps < 0.05), interhemispheric signal propagation (t = 2.53, p = 0.030), and TMS-induced early α-band synchronization (p = 0.020). Conclusion: Our study confirmed the local and remote after-effects of iTBS in reducing cortical inhibition in the M1. TMS-induced oscillations after iTBS for changed cortical excitability in patients with various neurological and psychiatric conditions are worth further exploration.

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