Corticospinal Plasticity in Bilateral Primary Motor Cortices Induced by Paired Associative Stimulation to the Dominant Hemisphere Does Not Differ between Young and Older Adults

Dickins, Daina S. E.; Kamke, Marc R.; Sale, Martin V.

doi:10.1155/2017/8319049

Cited by 9 publications

(8 citation statements)

References 65 publications

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“…From the demographic data, age is considered a major factor that is known to influence LTP-like cortical plasticity and sensorimotor integration (for a review, see Bhandari et al, 2016). For instance, PAS-induced changes in MEP amplitude have previously been reported to be substantially smaller in elderly healthy individuals relative to young ones (Müller-Dahlhaus et al, 2008), while another study found only a trend toward a main effect of age, with young adults showing increases in MEP amplitude relative to older adults (Dickins et al, 2017). Here, we found only a trend for a negative association between age and PAS response, with no significant differences between HC and MCI, or between PAS responders and non-responders.…”

Section: Discussionmentioning

confidence: 93%

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation

et al. 2019

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Transcranial magnetic stimulation (TMS) is a well-established tool in probing cortical plasticity in vivo . Changes in corticomotor excitability can be induced using paired associative stimulation (PAS) protocol, in which TMS over the primary motor cortex is conditioned with an electrical peripheral nerve stimulation of the contralateral hand. PAS with an inter-stimulus interval of 25 ms induces long-term potentiation (LTP)-like effects in cortical excitability. However, the response to a PAS protocol tends to vary substantially across individuals. In this study, we used univariate and multivariate data-driven methods to investigate various previously proposed determinants of inter-individual variability in PAS efficacy, such as demographic, cognitive, clinical, neurophysiological, and neuroimaging measures. Forty-one right-handed participants, comprising 22 patients with amnestic mild cognitive impairment (MCI) and 19 healthy controls (HC), underwent the PAS protocol. Prior to stimulation, demographic, genetic, clinical, as well as structural and resting-state functional MRI data were acquired. The two groups did not differ in any of the variables, except by global cognitive status. Univariate analysis showed that only 61% of all participants were classified as PAS responders, irrespective of group membership. Higher PAS response was associated with lower TMS intensity and with higher resting-state connectivity within the sensorimotor network, but only in responders, as opposed to non-responders. We also found an overall positive correlation between PAS response and structural connectivity within the corticospinal tract, which did not differ between groups. A multivariate random forest (RF) model identified age, gender, education, IQ, global cognitive status, sleep quality, alertness, TMS intensity, genetic factors, and neuroimaging measures (functional and structural connectivity, gray matter (GM) volume, and cortical thickness as poor predictors of PAS response. The model resulted in low accuracy of the RF classifier (58%; 95% CI: 42 − 74%), with a higher relative importance of brain connectivity measures compared to the other variables. We conclude that PAS variability in our sample was not well explained by factors known to influence PAS efficacy, emphasizing the need for future replication studies.

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Section: Discussionmentioning

confidence: 93%

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation

et al. 2019

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“…We did not identify any other studies for evaluation after reviewing the bibliographies of the full-text articles collected during the initial search. Finally, 29 studies (Rossini et al, 1992; Kossev et al, 2002; Sale and Semmler, 2005; Hortobágyi et al, 2006; Fujiyama et al, 2009, 2011, 2012, 2014; Pellicciari et al, 2009; Rogasch et al, 2009; Smith et al, 2009, 2011; Cirillo et al, 2010, 2011; Fathi et al, 2010; Todd et al, 2010; Degardin et al, 2011; Levin et al, 2011; Bernard and Seidler, 2012; Young-Bernier et al, 2012, 2014; Cuypers et al, 2013; Bashir et al, 2014; Opie and Semmler, 2014; Dickins et al, 2015, 2017; Opie et al, 2017, 2018; Emonson et al, 2019) fulfilled our inclusion criteria and were selected. Figure 1 depicts the search process and trial selection.…”

Section: Resultsmentioning

confidence: 99%

“…Randomization was not used in the 29 selected studies, and none of the studies described concealment of allocation. Nine studies (Fathi et al, 2010; Todd et al, 2010; Fujiyama et al, 2011, 2014; Young-Bernier et al, 2012, 2014; Opie and Semmler, 2014; Dickins et al, 2015, 2017) used appropriate blinding methods for the participants, and nine studies (Fathi et al, 2010; Cirillo et al, 2011; Fujiyama et al, 2012, 2014; Opie and Semmler, 2014; Dickins et al, 2017; Opie et al, 2017, 2018; Emonson et al, 2019) blinded the outcome assessments. All studies reported complete outcome data.…”

Section: Resultsmentioning

confidence: 99%

“…A total of 20 studies (Rossini et al, 1992; Sale and Semmler, 2005; Fujiyama et al, 2009, 2012; Rogasch et al, 2009; Smith et al, 2009; Cirillo et al, 2010, 2011; Fathi et al, 2010; Todd et al, 2010; Levin et al, 2011; Bernard and Seidler, 2012; Young-Bernier et al, 2012, 2014; Cuypers et al, 2013; Bashir et al, 2014; Dickins et al, 2015, 2017; Opie et al, 2017, 2018) providing numerical data for the MEP amplitude were included. Owing to the heterogeneity, a random-effects model was applied ( I 2 : 89%; p < 0.00001).…”

Section: Resultsmentioning

confidence: 99%

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Age-Related Changes in the Plasticity of Neural Networks Assessed by Transcranial Magnetic Stimulation With Electromyography: A Systematic Review and Meta-Analysis

Tang

Huang

et al. 2019

Front. Cell. Neurosci.

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Objective: The excitability of cerebral cortical cells, neural pathway, and neural networks, as well as their plasticity, are key to our exploration of age-related changes in brain structure and function. The combination of transcranial magnetic stimulation (TMS) with electromyography (EMG) can be applied to the primary motor cortex; it activates the underlying neural group and passes through the corticospinal pathway, which can be quantified using EMG. This meta-analysis aimed to analyze changes in cortical excitability and plasticity in healthy elderly individuals vs. young individuals through TMS-EMG.Methods: The Cochrane Library, Medline, and EMBASE databases were searched to identify eligible trials published from database inception to June 3, 2019. The Cochrane Risk of Bias Tool and improved Jadad scale were used to assess the methodological quality. A meta-analysis of the comparative effects was conducted using the Review Manager 5.3 software and Stata 14.0 software.Results: The pooled results revealed that the resting motor threshold values in the elderly group were markedly higher than those reported in the young group (mean difference [MD]: −2.35; 95% confidence interval [CI]: −3.69 to −1.02]; p < (0.00001). The motor evoked potential amplitude significantly reduced in the elderly group vs. the young group (MD: 0.18; 95% CI: 0.09–0.27; p < 0.0001). Moreover, there was significantly longer motor evoked potential latency in the elderly group (MD: −1.07; 95% CI: −1.77 to −0.37]; p =(0.003). There was no significant difference observed in the active motor threshold between the elderly and young groups (MD: −1.52; 95% CI: −3.47 to −0.42]; p =(0.13). Meanwhile, only two studies reported the absence of adverse events.Conclusion: We found that the excitability of the cerebral cortex declined in elderly individuals vs. young individuals. The findings of the present analysis should be considered with caution owing to the methodological limitations in the included trials. Additional high-quality studies are warranted to validate our findings.

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“…The associated conjecture that in the present case the requirement for attention to be directed toward the visual display may have served to attenuate increases in corticospinal excitability ordinarily realized by PAS (for both FCR and ECR), is consistent with general suppositions concerning the role of attention in regulating the effects of associative plasticity protocols (e.g., Stefan et al, 2004 ). Nonetheless, it should be noted that differentiating effects of attention on the expression of PAS induced changes in corticospinal excitability are not always obtained (e.g., Dickins et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Shaping the Effects of Associative Brain Stimulation by Contractions of the Opposite Limb

Carson

Rankin

2018

Front. Psychol.

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There has been an explosion of interest in methods that may promote neural plasticity by indirectly stimulating tissue in damaged brains using transient magnetic fields or weak electrical currents. A major limitation of these approaches is that the induced variations in brain activity tend to be diffuse. Thus far it has proved extremely difficult to target pathways from the brain to specific muscles. This is a particular challenge for applications in rehabilitation. Stroke survivors often exhibit abnormal patterns of muscle activation, including diminished specificity and high levels of co-contraction. For the clinical relevance of brain stimulation to be enhanced, it is desirable that the effects can be restricted to pathways controlling muscles that are the specific targets of movement therapy. We have demonstrated previously that increases in the excitability of corticospinal projections to forearm muscles generated by paired associative stimulation (PAS), are modulated by contractions ipsilateral to the site of the cortical stimulus. The current aim was to determine whether in chronic stroke survivors, simultaneous contractions performed by the non-paretic limb increase the muscle specificity of changes in the excitability of projections to the impaired limb induced by PAS. Ten chronic stroke survivors, 13 age-equivalent and 27 younger healthy controls, completed two separate sessions/conditions. In one (PAS+CONT), isometric wrist flexion contractions of the non-impaired limb were made simultaneously with PAS. In the other (PAS), associative stimulation only was applied. In all groups, PAS alone gave rise to large increases in the excitability of projections to a wrist extensor muscle (extensor carpi radialis – ECR) that was not the target of stimulation. In marked contrast, for the stroke survivors, following combined PAS and flexion contractions of the non-impaired limb, there was no corresponding elevation in the excitability of corticospinal projections to the ECR of the paretic limb. A similar effect was present for the healthy young adults, but not expressed clearly for the age-equivalent controls. The implications of these findings with respect to the clinical deployment of non-invasive brain stimulation in movement rehabilitation are discussed.

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Corticospinal Plasticity in Bilateral Primary Motor Cortices Induced by Paired Associative Stimulation to the Dominant Hemisphere Does Not Differ between Young and Older Adults

Cited by 9 publications

References 65 publications

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation

Determinants of Inter-Individual Variability in Corticomotor Excitability Induced by Paired Associative Stimulation

Age-Related Changes in the Plasticity of Neural Networks Assessed by Transcranial Magnetic Stimulation With Electromyography: A Systematic Review and Meta-Analysis

Shaping the Effects of Associative Brain Stimulation by Contractions of the Opposite Limb

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