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Claudia Martin Calderon, Ian Erkelens, Heidi Patterson, William Bobier, Benjamin Thompson; Modulation of oculomotor control & adaptation with cerebellar TMS: effects on saccades.. Journal of Vision 2017;17(10):737. doi: https://doi.org/10.1167/17.10.737.
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© ARVO (1962-2015); The Authors (2016-present)
The cerebellum plays a significant role in oculomotor control. Previous fMRI, repetitive TMS and lesion studies indicate its involvement in the adaptation of saccadic eye movements in humans. Building on this work, we applied continuous theta-burst (cTBS) TMS to the oculomotor vermis (OMV) of the posterior cerebellum to investigate its specific role in the execution of reactive pro-saccades and their adaptation to a double-step stimulus. 16 healthy controls completed 2 study visits where reactive pro-saccades and their adaptation to a gain reducing double-step stimulus were measured binocularly via infrared oculography at 250Hz. Active or sham cTBS (3-50Hz pulses at 200ms intervals for 40 seconds) was applied to the OMV using a 2x75mm butterfly coil at 80% of the individual's active motor threshold before completing the saccadic tasks at each visit. Stimulation sites were localized using the BrainSight® neuro-navigation system and anatomical landmarks. Compared to sham, active cTBS significantly reduced the adaptation of saccadic gain by 46.8% (p< 0.0001). The adaptive reduction of peak velocity after active cTBS was 79.4% less than sham (p< 0.0001), while the reduction of saccade duration was 55.2% less (p=0.009). Baseline pro-saccade gain was reduced by active (0.97±0.01) vs. sham (0.99±0.009) stimulation (p = 0.034). Baseline latency was not different between active (185ms) and sham (181ms) conditions (p = 0.34) and was not affected by stimulation type after adaptation (active = +1.2ms, sham = +2.5ms, p>0.50). These results demonstrate the central role of the OMV in the feed-forward control and feed-back driven adaptation of reactive pro-saccades, consistent with previous work. In addition, the results are the first to clearly establish the robust inhibitory effects of cTBS on oculomotor control and adaptation when applied to the OMV of the posterior cerebellum.
Meeting abstract presented at VSS 2017
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