Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex

Sale, Martin V., Nydam, Abbey S. and Mattingley, Jason B. (2017) Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex. Cortex, 88 32-41. doi:10.1016/j.cortex.2016.12.008

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Author Sale, Martin V.
Nydam, Abbey S.
Mattingley, Jason B.
Title Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex
Journal name Cortex   Check publisher's open access policy
ISSN 0010-9452
Publication date 2017-03-01
Sub-type Article (original research)
DOI 10.1016/j.cortex.2016.12.008
Open Access Status File (Author Post-print)
Volume 88
Start page 32
End page 41
Total pages 10
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Abstract Plasticity can be induced in human cortex using paired associative stimulation (PAS), which repeatedly and predictably pairs a peripheral electrical stimulus with transcranial magnetic stimulation (TMS) to the contralateral motor region. Many studies have reported small or inconsistent effects of PAS. Given that uncertain stimuli can promote learning, the predictable nature of the stimulation in conventional PAS paradigms might serve to attenuate plasticity induction. Here, we introduced stimulus uncertainty into the PAS paradigm to investigate if it can boost plasticity induction. Across two experimental sessions, participants (n = 28) received a modified PAS paradigm consisting of a random combination of 90 paired stimuli and 90 unpaired (TMS-only) stimuli. Prior to each of these stimuli, participants also received an auditory cue which either reliably predicted whether the upcoming stimulus was paired or unpaired (no uncertainty condition) or did not predict the upcoming stimulus (maximum uncertainty condition). Motor evoked potentials (MEPs) evoked from abductor pollicis brevis (APB) muscle quantified cortical excitability before and after PAS. MEP amplitude increased significantly 15 min following PAS in the maximum uncertainty condition. There was no reliable change in MEP amplitude in the no uncertainty condition, nor between post-PAS MEP amplitudes across the two conditions. These results suggest that stimulus uncertainty may provide a novel means to enhance plasticity induction with the PAS paradigm in human motor cortex. To provide further support to the notion that stimulus uncertainty and prediction error promote plasticity, future studies should further explore the time course of these changes, and investigate what aspects of stimulus uncertainty are critical in boosting plasticity.
Keyword Entropy
Prediction error
Paired associative stimulation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

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Created: Tue, 10 Jan 2017, 20:39:56 EST by Abbey Nydam on behalf of School of Psychology