Continuous theta-burst stimulation of the right superior temporal gyrus impairs self-motion perception.
Sensory input from the semicircular canals (SCC) and otolith organs is centrally combined with signals from other sensory modalities to continuously update the internal estimate of self-motion. Constant velocity vertical on-axis rotation leads to decay of the nystagmus response from the horizontal SCC and of perceived angular velocity (PAV), and when the rotation stops, a similar oppositely directed post-rotatory response occurs. Case reports and electrical stimulation studies suggest an involvement of the temporo-peri-Sylvian vestibular cortex in generating the PAV. Here, we transiently inhibited the right superior temporal gyrus (STG) by use of continuous theta-burst stimulation (cTBS) and predicted an accelerated decay of PAV compared to controls (n = 5 control session first, n = 1 cTBS session first). Constant velocity (100°/s) vertical on-axis rotations were applied over 75 s before (1 block) and after (3 blocks) cTBS over the right STG in six subjects. Breaks between the rotations (75 s) were initiated by abrupt stops. By use of a rotating potentiometer, subjects indicated the PAV during and after the chair rotations. Simultaneously eye positions were recorded using a scleral search coil. One subject was excluded for per-rotary analysis. Early after cTBS, the post-rotary PAV decay time constant (DTC) was significantly (9.4 ± 5.7 vs. 13.6 ± 5.9 s; p = 0.049) reduced (no directionality to this effect observed). Overall, post-rotary PAV showed a trend toward shortened DTC compared to the control trials (p = 0.086) in the first 25 min after cTBS, while per-rotary PAV was not significantly changed. Per-rotary and post-rotary aVOR DTC were not significantly changed after cTBS (p > 0.05). These findings support the hypothesis that the right STG is involved in mediating self-motion perception and can be modulated by cTBS.
Department of Neurology, The Johns Hopkins University School of Medicine, Path 2-210, 600 N. Wolfe St., Baltimore, MD, 21201, USA, atarnutzer@gmail.com.
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Tarnutzer
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Lasker
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Zee
D000054:Acceleration; D000328:Adult; D000368:Aged; D003627:Data Interpretation, Statistical; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010037:Otolithic Membrane / Q000502:physiology; D010812:Physical Stimulation; D010865:Pilot Projects; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation; D011795:Surveys and Questionnaires; D013702:Temporal Lobe / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation