Individual level reliability of PAS-induced neural plasticity

Abstract

Objective: We assessed the individual level reliability of neural plasticity changes induced by paired associative stimulation (PAS), which combines peripheral nerve stimulation with transcranial magnetic stimulation to induce short-term plastic changes in the brain. Methods: For 5 consecutive weeks, motor evoked potentials (MEPs) of 8 healthy subjects were acquired every 10 minutes post-PAS intervention for a period of 60 minutes. The post-PAS MEPs were evaluated against base- . CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under aThe copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/130856 doi: bioRxiv preprint first posted online Apr. 26, 2017; line MEPs using permutation and Kolmogorov-Smirnov tests to determine whether the MEP magnitudes changed after PAS. Moreover, various sample sizes of the MEP data were used to deduce the minimum number of MEPs needed to reliably detect individual propensity to neural plasticity. Results: Group analysis exhibited significant increase in post-PAS MEPs, confirming previous results. While high between-sessions variability was observed at individual level, data show that between 40 to 50 MEPs can reliably assess each subject's responsiveness to PAS. Subjects exhibited three different plasticity patterns: in the modulated hemisphere only, both hemispheres, or neither hemisphere. Conclusions: PAS can reliably assess individual differences in neural plasticity. Significance: A marker of individual plasticity may be useful to predict the effects of a motor rehabilitation, drug or other intervention to increase recovery of function after brain injury.

A Bayesian approach to analysing cortico-cortical associative stimulation induced increases in the excitability of corticospinal projections in humans

“…In such circumstances, inter-session variability of measurement contributes to that of the estimates for the experimental conditions. In a study in which a PAS protocol was administered on five separate occasions at 1-week intervals, intra-individual variations in the level of response to the intervention (i.e., across sessions) were considerable (Kim et al 2017 ). It is well established that the intra-day variability of TMS-derived measurements is lower than when measurements are obtained several days apart (Beaulieu et al 2017 ; Cavaleri et al 2017 ).…”