Individual level reliability of PAS-induced neural plasticity

Abstract

AbstractObjectiveWe 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.MethodsFor 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-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.ResultsGroup 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.ConclusionsPAS can reliably assess individual differences in neural plasticity.SignificanceA 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.HighlightsPaired associative stimulation (PAS) assesses neural plasticity non invasively.The study shows how PAS can reliably determine individual differences in plasticity.PAS may be used to predict intervention outcome or individualize treatment dose.