Continuous Theta Burst Stimulation to the Secondary Visual Cortex at 80% Active Motor Threshold Does Not Impair Central Vision in Humans During a Simple Detection Task

Abstract

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.