Fig. 2: Stimulation of the cerebellum phase-locked to ET movement.
From: Non-invasive suppression of essential tremor via phase-locked disruption of its temporal coherence
a Neuromodulation concept. ET is suppressed by perturbing its pathologic synchrony via cerebellar stimulation phase-locked to hand tremor oscillation. ET oscillation is measured via a motion sensor, instantaneous attributes of the oscillation (i.e. amplitude A(t), phase \({\Phi} (t)\)), are computed in real-time using ecHT, and electric currents are delivered, transcranially, to the cerebellum at a fixed phase lag. b Electrode configuration and cerebral electric fields distribution. (i) Stimulating currents were applied via a small skin electrode placed over the cerebellar hemisphere ipsilateral to measured hand tremor (10% axial nasion-inion distance lateral to inion) and a larger electrode placed over the contralateral frontal cortex (between F3 and F7 or F4 and F8 of the international 10–20 system). (ii) Finite element method (FEM) modelling of induced electric field for current amplitude of 2 mA. c Experimental design. d Phase-lag between stimulating currents and tremor movement vs. set phase lag during (i) whole stimulation period and (ii) 1st half (light blue) and 2nd half (dark blue) of the stimulation period. ‘No’, control sinusoidal current at the tremor frequency but without phase-locking; shown are box, 25 and 75% percentile values; horizontal red line, median value; horizontal black lines, data range; black markers, participants’ values; *p < 0.05, two-sided Omnibus test; n.s. non-significant; n = 11 participants. See Supplementary Table 2 for between conditions statistics. e Mean phase resultant vector length vs. set phase lag during the same periods as in (d); shown are mean ± st.d.; markers show participants’ values; ‘No’, stimulation with no phase locking; ‘Sh’, sham stimulation. two-sided ANOVA with post-hoc analysis using Wilcoxon signed-rank test; n = 11 participants; See Supplementary Table 3 for full statistics. f Mean phase resultant vector length vs. (i) tremor amplitude, (ii) st.d. tremor amplitude; shown black markers are trials’ mean values. Red line, linear regression, (i) line slope m = 0.59, p < 10−5, Pearson correlation test, (ii) m = −0.49, p < 10−16. g Same as (f) but (i) tremor frequency, m = −0.33, p < 10−7; (ii) st.d. tremor frequency, m = −0.66, p < 10−32. Source data are provided as a Source Data file.
