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

Clin Neurophysiol. 2017 May;128(5):763-769. doi: 10.1016/j.clinph.2017.02.011. Epub 2017 Feb 28.

Abstract

Objective: To examine the effect of priming paired associative stimulation (PAS) on the modulation of motor cortex (M1) plasticity in young and old adults.

Methods: Fifteen 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.

Results: In 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).

Conclusion: Data show that priming with PASLTP was effective in young but not old subjects.

Significance: These findings suggest a limited utility of priming PAS for augmenting plasticity induction in old adults.

Keywords: Ageing; Metaplasticity; Neuroplasticity; Paired-associative stimulation; Primary motor cortex; Transcranial magnetic stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aging / physiology
  • Association*
  • Evoked Potentials, Motor
  • Female
  • Humans
  • Male
  • Middle Aged
  • Motor Cortex / growth & development
  • Motor Cortex / physiology*
  • Neuronal Plasticity*
  • Repetition Priming*