Age-related differences in how the shape of alpha and beta oscillations change during reaction time tasks.

While the shape of cortical oscillations is increasingly recognised to be physiologically and functionally informative, its relevance to the aging motor system has not been established. We therefore examined the shape of alpha and beta band oscillations recorded at rest, as well as during performance of simple and go/no-go reaction time tasks, in 33 young (23.3 ± 2.

Investigating the Effects of Repetitive Paired-Pulse Transcranial Magnetic Stimulation on Visuomotor Training Using TMS-EEG.

I-wave periodicity repetitive paired-pulse transcranial magnetic stimulation (iTMS) can modify acquisition of a novel motor skill, but the associated neurophysiological effects remain unclear. The current study therefore used combined TMS-electroencephalography (TMS-EEG) to investigate the neurophysiological effects of iTMS on subsequent visuomotor training (VT). Sixteen young adults (26.

Modulation of dorsal premotor cortex differentially influences visuomotor adaptation in young and older adults.

The communication between dorsal premotor cortex (PMd) and primary motor cortex (M1) is important for visuomotor adaptation, but it is unclear how this relationship changes with advancing age. The present study recruited 21 young and 23 older participants for two experimental sessions during which intermittent theta burst stimulation (iTBS) or sham was applied over PMd. We assessed the effects of PMd iTBS on M1 excitability using motor evoked potentials (MEP) recorded from right first dorsal interosseous when single-pulse transcranial magnetic stimulation (TMS) was applied with posterior-anterior (PA) or anterior-posterior (AP) currents; and adaptation by quantifying error recorded during a visuomotor adaptation task (VAT).

The effects of intermittent theta burst stimulation over dorsal premotor cortex on primary motor cortex plasticity in young and older adults.

Previous transcranial magnetic stimulation (TMS) research suggests that the dorsal premotor cortex (PMd) influences neuroplasticity within the primary motor cortex (M1) through indirect (I) wave interneuronal circuits. However, it is unclear how the influence of PMd on the plasticity of M1 I-waves changes with advancing age. This study therefore investigated the neuroplastic effects of intermittent theta burst stimulation (iTBS) to M1 early and late I-wave circuits when preceded by iTBS (PMd iTBS-M1 iTBS) or sham stimulation (PMd sham-M1 iTBS) to PMd in 15 young and 16 older adults.

Transcutaneous auricular vagus nerve stimulation modifies cortical excitability in middle-aged and older adults.

There is a growing interest in the clinical application of transcutaneous auricular vagus nerve stimulation (taVNS). However, its effect on cortical excitability, and whether this is modulated by stimulation duration, remains unclear. We evaluated whether taVNS can modify excitability in the primary motor cortex (M1) in middle-aged and older adults and whether the stimulation duration moderates this effect.

Repetitive paired-pulse TMS increases motor cortex excitability and visuomotor skill acquisition in young and older adults.

Transcranial magnetic stimulation (TMS) over primary motor cortex (M1) recruits indirect (I) waves that can be modulated by repetitive paired-pulse TMS (rppTMS). The purpose of this study was to examine the effect of rppTMS on M1 excitability and visuomotor skill acquisition in young and older adults. A total of 37 healthy adults (22 young, 18-32 yr; 15 older, 60-79 yr) participated in a study that involved rppTMS at early (1.

Effect of current direction and muscle activation on motor cortex neuroplasticity induced by repetitive paired-pulse transcranial magnetic stimulation.

Repetitive paired-pulse transcranial magnetic stimulation (TMS) at indirect (I)-wave periodicity (iTMS) can increase plasticity in primary motor cortex (M1). Both TMS coil orientation and muscle activation can influence I-wave activity, but it remains unclear how these factors influence M1 plasticity with iTMS. We therefore investigated the influence of TMS coil orientation and muscle activation on the response to iTMS.

Modulation of dorsal premotor cortex differentially influences I-wave excitability in primary motor cortex of young and older adults.

Previous research using transcranial magnetic stimulation (TMS) has demonstrated weakened connectivity between dorsal premotor cortex (PMd) and motor cortex (M1) with age. While this alteration is probably mediated by changes in the communication between the two regions, the effect of age on the influence of PMd on specific indirect (I) wave circuits within M1 remains unclear. The present study therefore investigated the influence of PMd on early and late I-wave excitability in M1 of young and older adults.

Modulation of I-Wave Generating Pathways With Repetitive Paired-Pulse Transcranial Magnetic Stimulation: A Transcranial Magnetic Stimulation-Electroencephalography Study.

Objectives: Repetitive paired-pulse transcranial magnetic stimulation (iTMS) at indirect (I) wave intervals increases motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation (TMS) to primary motor cortex (M1). However, the effects of iTMS at early and late intervals on the plasticity of specific I-wave circuits remain unclear. This study therefore aimed to assess how the timing of iTMS influences intracortical excitability within early and late I-wave circuits.

Motor cortex plasticity is greater in endurance-trained cyclists following acute exercise.

Previous research using transcranial magnetic stimulation (TMS) has shown that plasticity within primary motor cortex (M1) is greater in people who undertake regular exercise, and a single session of aerobic exercise can increase M1 plasticity in untrained participants. This study aimed to examine the effect of an acute bout of exercise on M1 plasticity in endurance-trained (cyclists) and untrained individuals. Fourteen endurance-trained cyclists (mean ± SD; 23 ± 3.

Cerebellar transcranial direct current stimulation disrupts neuroplasticity of intracortical motor circuits.

While previous research using transcranial magnetic stimulation (TMS) suggest that cerebellum (CB) influences the neuroplastic response of primary motor cortex (M1), the role of different indirect (I) wave inputs in M1 mediating this interaction remains unclear. The aim of this study was therefore to assess how CB influences neuroplasticity of early and late I-wave circuits. 22 young adults (22 ± 2.

Assessment of cortical inhibition depends on inter individual differences in the excitatory neural populations activated by transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) is used to probe inhibitory intracortical neurotransmission and has been used to infer the neurobiological dysfunction that may underly several neurological disorders. One technique, short-interval intracortical inhibition (SICI), indexes gamma-aminobutyric acid (GABA) mediated inhibitory activity and is a promising biomarker. However emerging evidence suggests SICI does not exclusively represent GABAergic activity because it may be influenced by inter-individual differences in the specific excitatory neural populations activated by TMS.

Threshold Tracked Short-Interval Intracortical Inhibition More Closely Predicts the Cortical Response to Transcranial Magnetic Stimulation.

Objectives: Short-interval intracortical inhibition (SICI) is a paired-pulse transcranial magnetic stimulation (TMS) technique that is commonly used to quantify intracortical inhibitory tone in the primary motor cortex. Whereas conventional measures of SICI (C-SICI) quantify inhibition by the amplitude of the motor evoked potential (MEP), alternative measures involving threshold tracked SICI (TT-SICI) instead record the TMS intensity required to maintain a consistent MEP amplitude. Although both C-SICI and TT-SICI are thought to reflect inhibition mediated by γ-aminobutyric acid type A (GABA) receptors, recent evidence suggests that the mechanisms involved with each measure may not be equivalent.

Motor cortex plasticity and visuomotor skill learning in upper and lower limbs of endurance-trained cyclists.

Purpose: Studies with transcranial magnetic stimulation (TMS) show that both acute and long-term exercise can influence TMS-induced plasticity within primary motor cortex (M1). However, it remains unclear how regular exercise influences skill training-induced M1 plasticity and motor skill acquisition. This study aimed to investigate whether skill training-induced plasticity and motor skill learning is modified in endurance-trained cyclists.

Age-related changes in motor cortex plasticity assessed with non-invasive brain stimulation: an update and new perspectives.

It is commonly accepted that the brains capacity to change, known as plasticity, declines into old age. Recent studies have used a variety of non-invasive brain stimulation (NIBS) techniques to examine this age-related decline in plasticity in the primary motor cortex (M1), but the effects seem inconsistent and difficult to unravel. The purpose of this review is to provide an update on studies that have used different NIBS techniques to assess M1 plasticity with advancing age and offer some new perspective on NIBS strategies to boost plasticity in the ageing brain.

Interactions Between Cerebellum and the Intracortical Excitatory Circuits of Motor Cortex: a Mini-Review.

Interactions between cerebellum (CB) and primary motor cortex (M1) are critical for effective motor function. Although the associated neurophysiological processes are yet to be fully characterised, a growing body of work using non-invasive brain stimulation (NIBS) techniques has significantly progressed our current understanding. In particular, recent developments with both transcranial magnetic (TMS) and direct current (tDCS) stimulation suggest that CB modulates the activity of local excitatory interneuronal circuits within M1.

Assessing cerebellar-cortical connectivity using concurrent TMS-EEG: a feasibility study.

Combined single-pulse transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been used to probe the features of local networks in the cerebral cortex. Here, we investigated whether we can use this approach to explore long-range connections between the cerebellum and cerebral cortex. Ten healthy adults received single-pulse suprathreshold TMS to the cerebellum and an occipital/parietal control site with double-cone and figure-of-eight coils while cerebral activity was recorded.

Modulation of Motor Cortex Plasticity by Repetitive Paired-Pulse TMS at Late I-Wave Intervals Is Influenced by Intracortical Excitability.

The late indirect (I)-waves recruited by transcranial magnetic stimulation (TMS) over primary motor cortex (M1) can be modulated using I-wave periodicity repetitive TMS (iTMS). The purpose of this study was to determine if the response to iTMS is influenced by different interstimulus intervals (ISIs) targeting late I-waves, and whether these responses were associated with individual variations in intracortical excitability. Seventeen young (27.

Preferential Activation of Unique Motor Cortical Networks With Transcranial Magnetic Stimulation: A Review of the Physiological, Functional, and Clinical Evidence.

Objectives: The corticospinal volley produced by application of transcranial magnetic stimulation (TMS) over primary motor cortex consists of a number of waves generated by trans-synaptic input from interneuronal circuits. These indirect (I)-waves mediate the sensitivity of TMS to cortical plasticity and intracortical excitability and can be assessed by altering the direction of cortical current induced by TMS. While this methodological approach has been conventionally viewed as preferentially recruiting early or late I-wave inputs from a given populations of neurons, growing evidence suggests recruitment of different neuronal populations, and this would strongly influence interpretation and application of these measures.

TMS coil orientation and muscle activation influence lower limb intracortical excitability.

Introduction: Previous research with transcranial magnetic stimulation (TMS) indicates that coil orientation (TMS current direction) and muscle activation state (rest or active) modify corticospinal and intracortical excitability of upper limb muscles. However, the extent to which these factors influence corticospinal and intracortical excitability of lower limb muscles is unknown. This study aimed to examine how variations in coil orientation and muscle activation affect corticospinal and intracortical excitability of tibialis anterior (TA), a lower leg muscle.

Characterising the influence of cerebellum on the neuroplastic modulation of intracortical motor circuits.

The cerebellum (CB) has extensive connections with both cortical and subcortical areas of the brain, and is known to strongly influence function in areas it projects to. In particular, research using non-invasive brain stimulation (NIBS) has shown that CB projections to primary motor cortex (M1) are likely important for facilitating the learning of new motor skills, and that this process may involve modulation of late indirect (I) wave inputs in M1. However, the nature of this relationship remains unclear, particularly in regards to how CB influences the contribution of the I-wave circuits to neuroplastic changes in M1.