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

Older adults have been shown to exhibit a reduction in the lateralization of neural activity. Although neuroplasticity induced by noninvasive brain stimulation has been reported to be attenuated in the targeted motor cortex of older adults, it remains possible that the plasticity effects may instead manifest in a more distributed (bilateral) network. Furthermore, attention, which modulates neuroplasticity in young adults, may influence these effects. To address these questions, plasticity was induced in young (19–32 years) and older (65–78 years) adults using transcranial magnetic stimulation (TMS) paired with peripheral nerve stimulation. The plasticity effects induced by this paired associative stimulation (PAS) protocol in the targeted and nontargeted hemispheres were probed using TMS-induced motor-evoked potentials (MEPs) recorded from the abductor pollicis brevis (APB) muscle of each hand. PAS-induced effects were highly variable across individuals, with only half of the participants in each group demonstrating the expected increase in MEP amplitude. Contrary to predictions, however, PAS-induced corticospinal plasticity manifests predominately in the targeted hemisphere for both young and older adults. Attention to the target hand did not enhance corticospinal plasticity. The results suggest that plasticity does not manifest differently across bilateral corticospinal pathways between young and older adults.

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Transcranial Magnetic Stimulation Following A Paired Associative Stimulation Protocol Based On A Videogame Potentiates Cortical Plasticity And Motor Behavior

10.21203/rs.3.rs-775978/v1 ◽

2021 ◽

Author(s):

Arantzazu San Agustín ◽

Guillermo Asín-Prieto ◽

Juan C Moreno ◽

Antonio Oliviero ◽

José L Pons

Keyword(s):

Magnetic Stimulation ◽

Sham Group ◽

Motor Behavior ◽

Motor Evoked Potentials ◽

Single Pulse ◽

Main Task ◽

Abductor Pollicis Brevis ◽

Paired Associative Stimulation ◽

Dynamic Task ◽

Time Accuracy

Abstract BackgroundTranscranial Magnetic Stimulation (TMS) can induce synaptic plasticity potentiation following a paired associative stimulation (PAS) protocol, synchronizing a TMS single pulse with a movement task, named movement-related cortical stimulation (MRCS). However, MRCS plasticity induction and performance potentiation has been related exclusively to single movement tasks.MethodIn order to unveil the changes in motor learning produced by the MRCS protocol in complex movements, associated to Activities of Daily Living (ADL), we induced PAS changes in synchronization with a movement-related dynamic task by performing a customized videogame. We measured the task performance as well as nervous system excitability neuromodulation in 22 healthy subjects, analyzing Reaction Time (RT) and the peak-to-peak amplitude of the Motor Evoked Potentials (MEPs) respectively. The MEPs were recorded in the main task executor muscle, Abductor Pollicis Brevis (APB), and a secondary muscle, Abductor Digiti Minimi (ADM), before, right after, and 30 minutes after the intervention, in a real against sham group experimental parallel design. ResultsPAS application in synchronization with a complex task resulted in a motor performance potentiation effect, inducing shorter RTs when compared to the sham group. Moreover, it triggered long-term corticospinal plasticity mechanisms reflected in a MEP amplitude depression for the APB muscle at the higher intensity of recruitment curve and an enhancement of the corticospinal excitability of ADM muscle at around threshold intensity. RTs and ADM MEP amplitudes correlated positively in around threshold and high intensity assessments.ConclusionsWe conclude that the proposed PAS protocol facilitated the learning of time-accuracy movement in complex movement tasks, even if fatigue could be affecting the executor muscle excitability, and enhanced potentiation towards a passive muscle. This phenomenon can be very useful to develop neurorehabilitation strategies with complex movements (more similar to ADLs) and to avoid maladaptive plasticity related likely to fatigue.

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The Effect of Etomidate on Motor Evoked Potentials Induced by Transcranial Magnetic Stimulation in the Monkey

Neurosurgery ◽

10.1227/00006123-199012000-00012 ◽

1990 ◽

Vol 27 (6) ◽

pp. 936-942 ◽

Cited By ~ 30

Author(s):

Ramsis F. Ghaly ◽

James L. Stone ◽

Walter J. Levy ◽

Peter Roccaforte ◽

Edward B. Brunner

Keyword(s):

Transcranial Magnetic Stimulation ◽

Evoked Potentials ◽

Total Dose ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Mean Amplitude ◽

Abductor Hallucis ◽

Abductor Pollicis Brevis ◽

Hypnotic Agent ◽

The Mean

Abstract Etomidate (ET) is a known hypnotic agent in neuroanesthesia. This study was designed to examine the reliability of motor evoked potentials (MEPs) after transcranial magnetic stimulation in monkeys anesthetized intravenously with ET. The ET regimen was as follows: an initial dose (0.5 mg/kg) followed by 13 doses (0.2 mg/kg every 6-12 min; mean, 8.0 ± 1.3 min). The total dose administered was 3.1 mg/kg. The magnetic coil was placed over the MEP scalp stimulation region. Evoked electromyographic responses were recorded from the contralateral abductor pollicis brevis (APB) and abductor hallucis (AH) muscles of the fore- and hindlimbs, respectively. Reproducible MEP responses were consistently recorded while the animal was under total ET anesthesia. The coil demography was altered and the MEP scalp topography was moderately reduced by ET injections. Significant threshold elevation was noted after a total dose of 1.7 mg/kg for APB responses and 0.5 mg/kg for AH responses (P < 0.05). Marked prolongation of latency was observed after a dose of 0.5 mg/kg for APB MEPs and 2.5 mg/kg for AH MEPs (P < 0.05). MEP amplitude responses showed marked variability. Repeated doses of ET produced a mean threshold rise of 14 to 28% for the APB and 19 to 29% for the AH. The mean latency delay was 5 to 11% for the APB and 0.5 to 8% for the AH, while the mean amplitude depression was 24 to 59% for the APB and 15 to 50% for the AH. Apparent seizure activity or abnormalities in behavior and feeding were not noted over a 1-year period. We conclude that monitoring of MEPs induced by transcranial magnetic stimulation under ET anesthesia is feasible. Clear MEP responses can be maintained under ET anesthesia. ET caused alterations in MEPs induced by transcranial magnetic stimulation, and awareness of such changes is important. Further investigation in humans is recommended.

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Corticomotor plasticity and learning of a ballistic thumb training task are diminished in older adults

Journal of Applied Physiology ◽

10.1152/japplphysiol.00443.2009 ◽

2009 ◽

Vol 107 (6) ◽

pp. 1874-1883 ◽

Cited By ~ 101

Author(s):

Nigel C. Rogasch ◽

Tamara J. Dartnall ◽

John Cirillo ◽

Michael A. Nordstrom ◽

John G. Semmler

Keyword(s):

Older Adults ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Short Interval ◽

Intracortical Inhibition ◽

Training Task ◽

Abductor Pollicis Brevis ◽

Corticomotor Excitability ◽

Old Adults ◽

Young Subjects

This study examined changes in corticomotor excitability and plasticity after a thumb abduction training task in young and old adults. Electromyographic (EMG) recordings were obtained from right abductor pollicis brevis (APB, target muscle) and abductor digiti minimi (ADM, control muscle) in 14 young (18–24 yr) and 14 old (61–82 yr) adults. The training task consisted of 300 ballistic abductions of the right thumb to maximize peak thumb abduction acceleration (TAAcc). Transcranial magnetic stimulation (TMS) of the left primary motor cortex was used to assess changes in APB and ADM motor evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) before, immediately after, and 30 min after training. No differences in corticomotor excitability (resting and active TMS thresholds, MEP input-output curves) or SICI were observed in young and old adults before training. Motor training resulted in improvements in peak TAAcc in young (177% improvement, P < 0.001) and old (124%, P = 0.005) subjects, with greater improvements in young subjects ( P = 0.002). Different thumb kinematics were observed during task performance, with increases in APB EMG related to improvements in peak TAAcc in young ( r2 = 0.46, P = 0.008) but not old ( r2 = 0.09, P = 0.3) adults. After training, APB MEPs were 50% larger ( P < 0.001 compared with before) in young subjects, with no change after training in old subjects ( P = 0.49), suggesting reduced use-dependent corticomotor plasticity with advancing age. These changes were specific to APB, because no training-related change in MEP amplitude was observed in ADM. No significant association was observed between change in APB MEP and improvement in TAAcc with training in individual young and old subjects. SICI remained unchanged after training in both groups, suggesting that it was not responsible for the diminished use-dependent corticomotor plasticity for this task in older adults.

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Effect of specific trapezius exercises vs. coordination training on corticomotor control of neck muscles

Scandinavian Journal of Pain ◽

10.1016/j.sjpain.2012.05.039 ◽

2012 ◽

Vol 3 (3) ◽

pp. 187

Author(s):

B. Rittig-Rasmussen ◽

H. Kasch ◽

A. Fuglsang-Frederiksen ◽

T.S. Jensen ◽

P. Svensson

Keyword(s):

Muscle Strength ◽

Healthy Subjects ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Trapezius Muscle ◽

Training Methods ◽

Specific Training ◽

Abductor Pollicis Brevis ◽

Coordination Training ◽

Over Time

AbstractObjectiveTo test the effect of different neck training methods on motor evoked potentials (MEPs) from the trapezius muscle. We hypothesized that training of the trapezius muscle would significantly increase MEPs, indicating facilitation of the corticomotor pathways. Additional experiments investigated the influence of muscle strength, muscle fatigue, and correlations between MEP amplitudes and behavioral aspects of motor learning.MethodsTranscranial magnetic stimulation (TMS) was used to elicit MEPs from the trapezius muscle and the abductor pollicis brevis (APB) muscle in 60 healthy subjects in three conditions: (1) specific trapezius training, (2) coordination training of the neck, and (3) no training.ResultsSpecific training yielded an increase in MEPs 1 h (p = 0.001) and 7 days (p = 0.001) after training compared with baseline; no significant changes were seen after coordination training or no training. MEPs from the APB muscle did not change over time in any of the conditions. Muscle strength increased by 8% after specific training, but no subjective or objective measures of fatigue were observed.ConclusionsThe results showed that only specific training significantly increased trapezius MEPs for up to 7 days, indicating facilitation of the corticomotor pathways. These findings may help improve the future clinical management of neck pain.

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Onset Latency of Motor Evoked Potentials in Motor Cortical Mapping with Neuronavigated Transcranial Magnetic Stimulation

The Open Neurology Journal ◽

10.2174/1874205x01509010062 ◽

2015 ◽

Vol 9 (1) ◽

pp. 62-69 ◽

Cited By ~ 16

Author(s):

Elisa Kallioniemi ◽

Minna Pitkänen ◽

Laura Säisänen ◽

Petro Julkunen

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Motor Evoked Potential ◽

Cortical Mapping ◽

Abductor Pollicis Brevis ◽

Motor Pathways ◽

Motor Mapping ◽

Cortical Motor ◽

Abductor Digiti Minimi

Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP) amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stable parameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provide information about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from the MEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique of MEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthanded volunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by using MEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in the centre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. In conclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathways from those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tract connections at the subcortical level will need to be verified in future studies with patients.

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Locating and Outlining the Cortical Motor Representation Areas of Facial Muscles With Navigated Transcranial Magnetic Stimulation

Neurosurgery ◽

10.1227/neu.0000000000000798 ◽

2015 ◽

Vol 77 (3) ◽

pp. 394-405 ◽

Cited By ~ 11

Author(s):

Laura Säisänen ◽

Petro Julkunen ◽

Samuli Kemppainen ◽

Nils Danner ◽

Arto Immonen ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Evoked Potentials ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Navigated Transcranial Magnetic Stimulation ◽

Tumor Patients ◽

Abductor Pollicis Brevis ◽

Facial Muscles ◽

Cortical Motor

Abstract BACKGROUND: Navigated transcranial magnetic stimulation (nTMS) has become established as an accurate noninvasive technique for mapping the functional motor cortex for the representation areas of upper and lower limb muscles but not yet for facial musculature. OBJECTIVE: To characterize the applicability and clinical impact of using nTMS to map cortical motor areas of facial muscles in healthy volunteers and neurosurgical tumor patients. METHODS: Eight healthy volunteers and 12 patients with tumor were studied. The motor threshold (MT) was determined for the abductor pollicis brevis and mentalis muscles. The lateral part of the motor cortex was mapped with suprathreshold stimulation intensity, and motor evoked potentials were recorded from several facial muscles. The patient protocol was modified according to the clinical indication. RESULTS: In all healthy subjects, motor evoked potentials were elicited in the mentalis (mean latency, 13.4 milliseconds) and orbicularis oris (mean latency, 12.6 milliseconds) muscles. At 110% of MT of the mentalis, the motor evoked potentials of facial muscles were elicited mainly in the precentral gyrus but also from one gyrus anterior and posterior to it. The cortical areas applicable for mapping were limited by an artifact attributable to direct peripheral nerve stimulation. The mapping protocol was successful in 10 of 12 tumor patients at locating the representation area of the lower facial muscles. The MT of the facial muscles was significantly higher than that of the abductor pollicis brevis. CONCLUSION: nTMS is an applicable and clinically beneficial noninvasive method to preoperatively map the cortical representation areas of the facial muscles in the lower part of the face. Instead of using the MT of the abductor pollicis brevis, the stimulus intensity during mapping should be proportioned to the MT of a facial muscle.

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Treatment of patients with cervical and upper thoracic incomplete spinal cord injury using repetitive transcranial magnetic stimulation

The International Journal of Artificial Organs ◽

10.1177/0391398819887754 ◽

2019 ◽

Vol 43 (5) ◽

pp. 323-331

Author(s):

Katarzyna Leszczyńska ◽

Agnieszka Wincek ◽

Wojciech Fortuna ◽

Juliusz Huber ◽

Jagoda Łukaszek ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Transcranial Magnetic Stimulation ◽

Surface Electromyography ◽

Magnetic Stimulation ◽

Motor Evoked Potentials ◽

Repetitive Transcranial Magnetic Stimulation ◽

Incomplete Spinal Cord Injury ◽

Abductor Pollicis Brevis ◽

Cord Injury

Purpose: To evaluate the short- and long-term effectiveness of repetitive transcranial magnetic stimulation with parameters based on results of comparative neurophysiological studies in patients with incomplete spinal cord injury. Results may help to understand mechanisms responsible for regeneration of the incomplete spinal cord after injury. Methods: Repetitive transcranial magnetic stimulation sessions (three to five sessions per month for not less than 5 months) to 15 patients with C4-Th2 incomplete spinal cord injury were applied with individually designed parameters. One session consisted of bilateral stimulation of the primary motor cortex (for 10 min each with 800 stimuli in 2-s lasting trains and the inter-train intervals of 28 s) with frequency at 20–22 Hz and stimulus strength that was 70%–80% of the resting motor threshold (0.84–0.96 T). Recordings of surface electromyography at rest and during the attempt of maximal muscle contractions and motor evoked potentials were performed from abductor pollicis brevis and tibialis anterior muscles bilaterally. Amplitude parameters of surface electromyography and motor evoked potentials were used as outcomes. All neurophysiological tests were comparatively applied before and after treatment. Results: Decrease in surface electromyography amplitudes recorded at rest from abductor pollicis brevis (p = 0.009), increase in surface electromyography amplitudes during maximal contraction of abductor pollicis brevis (p = 0.03) and increase in motor evoked potential parameters recorded from abductor pollicis brevis (p = 0.04) were found. Conclusion: Proposed repetitive transcranial magnetic stimulation algorithm reduced the increased muscle tension in upper extremity muscles, improved the function of upper extremity muscle motor units and slightly improved the transmission of efferent neural impulses within spinal pathways. Besides functional recovery in descending spinal pathways, repetitive transcranial magnetic stimulation may also inhibit inevitable pathological changes in nerves.

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Bilateral Motor Responses to Transcranial Magnetic Stimulation in Preterm Children at 9 Years of Age

Neuropediatrics ◽

10.1055/s-0041-1726127 ◽

2021 ◽

Author(s):

A. Marita Valkama ◽

Seppo O. Rytky ◽

Päivi M. Olsén

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Corticospinal Tract ◽

Motor Evoked Potentials ◽

Abductor Pollicis Brevis ◽

Motor Responses ◽

Motor Disability ◽

Motor Tracts ◽

Preterm Born ◽

Muscle Responses

Abstract Objective This study was aimed to evaluate motor tracts integrity in nondisabled preterm-born (PT) children at 9 years of age. Methods Overall, 18 PT and 13 term-born (T) children without motor disability were assessed by transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were measured bilaterally from the abductor pollicis brevis (APB) and the tibialis anterior (TA) muscles. Muscle responses could be stimulated from all patients. Results Overall, 83.3 and 23.1% of PT and T children, respectively, had mild clumsiness (p = 0.001). One PT and three T children had immediate bilateral responses in the upper extremities. Seven PT children had delayed ipsilateral APB responses after left and ten after right TMS. Three controls had delayed ipsilateral responses. Ipsilateral lower extremity responses were seen in one PT after right and two PT children and one T child after left TMS. The results did not correlate to groups, genders, clumsiness, or handedness. Conclusion Children of PT and T may have bilateral motor responses after TMS at 9 years of age. Ipsilateral conduction emerges immediately or more often slightly delayed and more frequently in upper than in lower extremities. Significance Bilateral motor conduction reflects developmental and neurophysiological variability in children at 9 years of age. MEPs can be used as a measure of corticospinal tract integrity in PT children.

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