Neural Noise- The integrity of double-blinding of continuous theta-burst stimulation (cTBS) targeting the supplementary motor area (SMA) has been examined in a within-subjects design.1
- This methodology is relevant to non-invasive neuromodulation and trial design in clinical neurophysiology.1 1
Weekly enrichment (2026-07-20)
- The source is a Letter in Clinical Neurophysiology (2026 Mar;183:2111482; Epub 2025 Dec 17; DOI 10.1016/j.clinph.2025.2111482) by Melker Hagsäter, Jonatan Malmros, Jonas Persson, Jonas Jester-Broms, and Robert Bodén, spanning the University of Gothenburg, Uppsala University, and Karolinska Institutet.2
- It examines the integrity of double-blinding for continuous theta-burst stimulation (cTBS) delivered to the supplementary motor area (SMA) in a within-subjects (crossover) design, where the same participant receives both active and sham sessions — a layout especially vulnerable to unblinding because subjects can directly compare conditions.2
- The record is indexed as a Letter with no abstract available, and the full text was not retrievable through open channels, so specific quantitative results (sample size, blinding-index values, guess accuracy) are not reported in the accessible sources.2
- Blinding integrity in TMS trials is typically quantified with the James Blinding Index (0 = complete unblinding, 0.5 = guessing at chance, 1 = complete blinding) or the Bang Blinding Index, computed from end-of-study guesses of active vs. sham allocation plus confidence ratings.3
- Context on why this matters: in dorsomedial-prefrontal iTBS for depression, 74% of participants correctly guessed their allocation after a single session, indicating blinding can break very early even with a placebo coil plus transcutaneous electrical nerve stimulation as sham.4
- By contrast, a double-blind cerebellar iTBS trial in bipolar disorder reported a patient James Blinding Index of 0.58 (95% CI 0.46–0.70), consistent with chance-level guessing, while researchers guessed somewhat better than chance (index 0.34, 95% CI 0.21–0.46), using a coil rotated 180° plus cutaneous electrical stimulation for sham.3
- Robust sham matching requires reproducing the auditory click and scalp/tactile sensation of active stimulation; earlier work by Flanagan et al. (2019) specifically assessed blinding success of sham-controlled motor-cortex iTBS from participant perceptions, underscoring that sensory differences, not the magnetic field, are the main cue that breaks blinding.5
- For BCI and neuromodulation trial design, within-subjects cTBS studies of the SMA — a region implicated in motor preparation and response inhibition — depend on verified blinding to separate genuine neurophysiological effects (e.g., MEP or corticospinal changes) from placebo and expectancy effects.2