Modulating motor cortical neuroplasticity with priming paired associative stimulation in young and old adults

Publication date: May 2017
Source:Clinical Neurophysiology, Volume 128, Issue 5
Author(s): George M. Opie, Aylin K. Post, Michael C. Ridding, Ulf Ziemann, John G. Semmler
ObjectiveTo examine the effect of priming paired associative stimulation (PAS) on the modulation of motor cortex (M1) plasticity in young and old adults.MethodsFifteen young (20–27yrs) and 15 old (61–79yrs) subjects participated in 3 experimental sessions, with each session involving two consecutive PAS protocols separated by 10mins. The first (priming) protocol was either PASLTP (ISI=N20 latency+2ms), PASLTD (ISI=N20 latency−10ms), or PASControl (ISI=100ms), whereas the second (test) protocol was always PASLTP. Changes in M1 excitability were assessed from motor evoked potentials (MEPs) in a hand muscle.ResultsIn young subjects, MEPs were larger after PASLTP+PASLTP than PASLTD+PASLTP (P<0.0001) and PASControl+PASLTP (P=0.0008), whereas the response to PASControl+PASLTP was not different to PASLTD+PASLTP (P=0.3). In old subjects, MEPs were smaller after PASLTP+PASLTP compared with PASControl+PASLTP (P=0.02), whereas PASLTD+PASLTP was similar to PASControl+PASLTP (P=0.08). Age-related comparisons within each priming condition showed that the response to PASLTP+PASLTP was significantly greater in young subjects (P=0.03).ConclusionData show that priming with PASLTP was effective in young but not old subjects.SignificanceThese findings suggest a limited utility of priming PAS for augmenting plasticity induction in old adults.



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