Variability and Reliability of Paired-Pulse Depression and Cortical Oscillation Induced by Median Nerve Stimulation

Hideaki Onishi,Yasuto Inukai,Kei Saito,Daisuke Sato,Shigeki Kameyama,Hiroshi Shirozu,Shota Miyaguchi,Naofumi Otsuru,Sho Kojima,Hiroyuki Tamaki,Koya Yamashiro

doi:10.1007/s10548-018-0648-5

Abstract

Paired-pulse depression (PPD) has been widely used to investigate the functional profiles of somatosensory cortical inhibition. However, PPD induced by somatosensory stimulation is variable, and the reasons for between- and within-subject PPD variability remains unclear. Therefore, the purpose of this study was to clarify the factors influencing PPD variability induced by somatosensory stimulation. The study participants were 19 healthy volunteers. First, we investigated the relationship between the PPD ratio of each component (N20m, P35m, and P60m) of the somatosensory magnetic field, and the alpha, beta, and gamma band changes in power [event-related desynchronization (ERD) and event-related synchronization (ERS)] induced by median nerve stimulation. Second, because brain-derived neurotrophic factor (BDNF) gene polymorphisms reportedly influence the PPD ratio, we assessed whether BDNF genotype influences PPD ratio variability. Finally, we evaluated the test–retest reliability of PPD and the alpha, beta, and gamma ERD/ERS induced by somatosensory stimulation. Significant positive correlations were observed between the P60m_PPD ratio and beta power change, and the P60m_PPD ratio was significantly smaller for the beta ERD group than for the beta ERS group. P35m_PPD was found to be robust and highly reproducible; however, P60m_PPD reproducibility was poor. In addition, the ICC values for alpha, beta, and gamma ERD/ERS were 0.680, 0.760, and 0.552 respectively. These results suggest that the variability of PPD for the P60m deflection may be influenced by the ERD/ERS magnitude, which is induced by median nerve stimulation.

Highlights

The paired-pulse stimulation (PPS) paradigm has been widely used to investigate the functional profiles of somatosensory cortical inhibition, known as paired-pulse depression (PPD), pre-pulse inhibition, or sensory gating, using1 3 Vol:.(1234567890)Brain Topography (2018) 31:780–794 auditory or somatosensory stimulation (Braff et al 2001; Cheng et al 2016, 2017; Huttunen et al 2008; Swerdlow et al 2005)
We further examined the test–retest reliability of PPD and the alpha, beta, and gamma event-related desynchronization (ERD)/event-related synchronization (ERS) induced by somatosensory stimulation using neuromagnetic data
We investigated PPD variability and reliability induced by median nerve stimulation using MEG

Summary

Introduction

The paired-pulse stimulation (PPS) paradigm has been widely used to investigate the functional profiles of somatosensory cortical inhibition, known as paired-pulse depression (PPD), pre-pulse inhibition, or sensory gating, using1 3 Vol:.(1234567890)Brain Topography (2018) 31:780–794 auditory or somatosensory stimulation (Braff et al 2001; Cheng et al 2016, 2017; Huttunen et al 2008; Swerdlow et al 2005). PPD is induced by stimulating with two pulses separated by a 100–2000 ms inter-pulse interval (ISI) (Cheng et al 2016, 2017; Onishi et al 2016; Xu et al 2009). It is evaluated as the amplitude ratio of the second stimulus (test stimulus, TS) response to the first stimulus (conditioning stimulus, CS) response. In human studies, PPD induced by somatosensory stimulation is variable, and is sometimes deficient even in healthy young subjects (Lenz et al 2012; Onishi et al 2016). If PPD measurements vary between sessions, the statistical power of these measurements is decreased, which limits the robustness of conclusions made regarding the effects of the studied drug, treatment, or disease

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