Increasing motor cortex plasticity with spaced paired associative stimulation at different intervals in older adults. (26th October 2017)

• Record Type: Journal Article
• Authors: Sidhu, Simranjit K.; Pourmajidian, Maryam; Opie, George M.; Semmler, John G.
• Is Part Of: European journal of neuroscience. Volume 46:Number 11(2017)
• Page Start: 2674
• Page End: 2683
• Publication Date: 2017-10-26
• Subjects: ageing -- metaplasticity -- neuroplasticity -- transcranial magnetic stimulation; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.13729
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: The ability of priming non‐invasive brain stimulation (NIBS) to modulate neuroplasticity induction (i.e. metaplasticity) within primary motor cortex (M1) may be altered in older adults. Previous studies in young subjects suggest that consecutive NIBS protocols interact in a time‐dependent manner and involve homoeostatic metaplasticity mechanisms. This was investigated in older adults by assessing the response to consecutive blocks of paired‐associative stimulation (PAS) separated by different inter‐PAS intervals (IPIs). Fifteen older (62–82 years) subjects participated in four sessions, with each session involving two PAS blocks separated by IPIs of 10 (IPI10 ) or 30 (IPI30 ) mins. For each IPI, the first (priming) PAS block was either PASLTP (N20 latency + 2 ms) or PASLTD (N20 latency − 10 ms), while the second (test) PAS block was always PASLTP . Changes in M1 excitability were assessed by recording motor evoked potentials from a muscle of the right hand. For both IPIs, the response produced by PASLTD ‐primed PASLTP was significantly greater than the response produced by PASLTP ‐primed PASLTP . Furthermore, the effects of PASLTD priming on PASLTP were significantly greater for IPI30 . These findings suggest that priming PAS can increase plasticity induction in older adults, and this occurs through mechanisms involving homoeostatic metaplasticity. They also demonstrate that the timing between priming and test NIBS is a crucial determinant of this effect, with a 30‐min interval being most effective. Providing a 30‐min delay between priming NIBS and motor training may improve the efficacy of NIBS in augmenting motor performance and learning in the elderly. Abstract : We examined the time‐dependant ability of priming paired associated stimulation (PAS) to modulate subsequent test PAS within primary motor cortex of older adults. The effects of priming PAS on test PAS potentiation were significantly greater for a 30‐min inter‐PAS inter‐valuing depressive priming PAS. We suggest that priming with depressive PAS using a longer delay may improve the efficacy of PAS in augmenting motor performance and learning in the elderly.