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1.
Background
the influence of pulse width, pulse waveform and current direction on transcranial magnetic stimulation (TMS) outcomes is of critical importance. However, their effects have only been investigated indirectly with motor-evoked potentials (MEP). By combining TMS and EEG it is possible to examine how these factors affect evoked activity from the cortex and compare that with the effects on MEP.Objective
we used a new controllable TMS device (cTMS) to vary systematically pulse width, pulse waveform and current direction and explore their effects on global and local TMS-evoked EEG response.Methods
In 19 healthy volunteers we measured (1) resting motor threshold (RMT) as an estimate of corticospinal excitability; (2) global mean field power (GMFP) as an estimate of global cortical excitability; and (3) local mean field power (LMFP) as an estimate of local cortical excitability.Results
RMT was lower with monophasic posterior-to-anterior (PA) pulses that have a longer pulse width (p?<?0.001). After adjusting for the individual motor threshold of each pulse type we found that (a) GMFP was higher with monophasic pulses (p?<?0.001); (b) LMFP was higher with longer pulse width (p?=?0.015); (c) early TEP polarity was modulated depending on the current direction (p?=?0.01).Conclusions
Despite normalizing stimulus intensity to RMT, we found that local and global responses to TMS vary depending on pulse parameters. Since EEG responses can vary independently of the MEP, titrating parameters of TMS in relation to MEP threshold is not a useful way of ensuring that a constant set of neurons is activated within a cortical area. 相似文献2.
Martin Sommer Matteo Ciocca Raffaella Chieffo Paul Hammond Andreas Neef Walter Paulus John C. Rothwell Ricci Hannah 《Brain stimulation》2018,11(3):558-565
Background
Biphasic pulses produced by most commercially available TMS machines have a cosine waveform, which makes it difficult to study the interaction between the two phases of stimulation.Objective
We used a controllable pulse TMS (cTMS) device delivering quasi-rectangular pulse outputs to investigate whether monophasic are more effective than biphasic pulses.Methods
Temporally symmetric (“biphasic”) or highly asymmetric (“monophasic”) charge-balanced biphasic stimuli were used to target the hand area of motor cortex in the anterior-posterior (AP) or posterior-anterior (PA) initial current direction.Results
We observed the lowest motor thresholds and shortest motor evoked potential (MEP) latencies with initial PA pulses, and highest thresholds and longest latencies with AP pulses. Increasing pulse symmetry tended to increase threshold with a PA direction whereas it lowered thresholds and shortened latencies with an AP direction. Furthermore, it steepened the MEP input-output curve with both directions.Conclusions
“Biphasic” TMS pulses can be viewed as two monophasic pulses of opposite directions, each stimulating a different set of interneurons with different thresholds (PA?<?AP). At threshold, the reverse phase of an initially PA pulse increases threshold compared with “monophasic” stimulation. At higher intensities, the reverse phase begins to activate AP-sensitive neurones and increase the effectiveness of stimulation above that of a “monophasic” PA pulse. “Biphasic” stimulation with initially AP pulses is dominated at threshold by activation produced by the lower threshold reverse (PA) phase.Significance
The effects of biphasic stimulation are best understood as the summed output of two independent sets of directionally selective neural populations. 相似文献3.
Franco Amaya Walter Paulus Stefan Treue David Liebetanz 《Clinical neurophysiology》2010,121(12):2143-2151
Objective
Externally induced neuroplasticity may be of therapeutic value in several neuro-psychiatric disorders. To facilitate research on mechanisms and to make possible the design of prospective, advanced stimulation protocols without exposing human subjects to risk, we have developed a primate model which allows us to assess changes of motor cortical excitability using transcranial magnetic stimulation (TMS).Methods
TMS hand muscle representation and cortical excitability were determined in two awake trained rhesus monkeys. Neuroplastic changes of cortical excitability were established by 13 min of paired associative stimulation (PAS) with interstimulus intervals of either 15 or 5 ms.Results
The representational areas of FDI and APB muscles (3.02–4.96 cm2) were located between the spur of the arcuate and the superior precentral sulcus, indicating the potential to carry out spatially selective cortical stimulation. PAS with an interstimulus interval of 15 ms strongly increased cortical excitability for up to two hours, while 5 ms interval had no effect.Conclusions
This first systematic TMS and PAS primate study demonstrates that the trained rhesus monkeys represent an exceptional animal model that allows cortical TMS mapping as well as non–invasive assessment and induction of cortical neuroplasticity.Significance
This animal model offers additional advantageous options not possible with humans, namely an alternative to invasive, morphological or molecular analyses, making it highly suitable for preclinical development of advanced neuroplasticity paradigms without exposing human subjects to risk. 相似文献4.
Objective
To examine the effects of theta burst stimulation (TBS) and paired associative stimulation (PAS) on excitability in the human motor cortex.Methods
Sixteen healthy young participants received intermittent TBS (iTBS) or PAS to the primary motor cortex on two testing occasions, at least a week apart. Ten of the participants also received iTBS or PAS after conditioning with continuous TBS on two other occasions. Cortical excitability was assessed with single TMS pulses to the motor cortex. Motor evoked potentials (MEPs) were measured from the first dorsal interosseus (FDI) muscle before TBS or PAS stimulation, and every 10 min for 60 min after stimulation. Changes in excitability were compared against the potential for motor learning, assessed with the rotor pursuit task.Results
After the PAS protocol MEP amplitudes were significantly increased. This increase was greater than after intermittent TBS, which did not change MEPs significantly. Conditioning with continuous TBS showed no significant effect. Participants’ responses were not correlated across protocols and were not correlated with rotor pursuit learning.Conclusions
PAS was the only protocol which induced significant increases in MEP amplitude.Significance
PAS is robust in inducing excitatory cortical change. This makes it a suitable protocol for testing plasticity in healthy and patient groups. 相似文献5.
Background
Patients with a psychogenic paresis have difficulties performing voluntary movements. Typically, diagnostic interventions are normal. We tested whether patients with a psychogenic lower limb paresis exhibit abnormal motor excitability during motor imagery or movement observation.Methods
Transcranial magnetic stimulation (TMS) with single and paired pulses was used to explore motor excitability at rest, during imagination of ankle dorsiflexions and during watching another person perform ankle dorsiflexions. Results obtained in ten patients with a flaccid psychogenic leg paresis were compared with a healthy age-matched control group. In addition, results of two patients with a psychogenic fixed dystonia of the leg are presented.Results
During rest, motor excitability evaluated by motor thresholds, size of motor-evoked potentials (MEP) by single pulse TMS, intracortical inhibition and intracortical facilitation tested by paired-pulse TMS were similar in patients and healthy subjects. MEPs recorded in five patients during movement observation were also comparable across the two groups. During motor imagery, patient MEPs were significantly smaller than in the control group and smaller than during rest, indicating an inhibition.Conclusion
In patients with motor conversion disorder, the imagination of own body movements induces a reduction of corticospinal motor excitability whereas it induces an excitability increase in healthy subjects. This discrepancy might be the electrophysiological substrate of the inability to move voluntarily. Watching another person perform movements induces a normal excitability increase, indicating a crucial role of the perspective and suggesting that focusing the patient's attention on a different person might become a therapeutic approach. 相似文献6.
Bagnato S Boccagni C Sant'angelo A Prestandrea C Rizzo S Galardi G 《Clinical neurophysiology》2012,123(10):1937-1941
Objective
Patients in coma who fail to wake develop a condition known as a vegetative state (VS). While we know that some cortical activities exist in patients in VS, it remains unclear whether interneuronal modulation can be abnormal in the cerebral cortex of these patients. The aim of the study was to evaluate the inhibitory and excitatory interneuronal circuits in patients in VS following a traumatic brain injury.Methods
Cortical excitability was studied in 5 VS patients and in 10 healthy subjects using paired pulses transcranial magnetic stimulation (TMS). Resting motor threshold and intracortical inhibition and facilitation at short intervals (2 and 10 ms, respectively) were evaluated. Two patients were studied again after their level of consciousness transitioned into a minimally conscious state (MCS).Results
Both intracortical inhibition and facilitation were significantly reduced in patients compared to healthy subjects (p < 0.05). In addition, these results did not significantly change in the 2 patients who evolved into a MCS.Conclusions
This is the first report showing an abnormal cortical excitability in patients in VS.Significance
Our findings suggest a pathophysiological base for future work aiming to restore the lack of interneuronal transmission in patients in VS. 相似文献7.
IntroductionMotor evoked potentials (MEP) in response to anteroposterior transcranial (AP) magnetic stimulation (TMS) are sensitive to the TMS pulse shape. We are now able to isolate distinct pulse properties, such as pulse width and directionality and evaluate them individually. Different pulse shapes induce different effects, likely by stimulating different populations of neurons. This implies that not all neurons respond in the same manner to stimulation, possibly, because individual segments of neurons differ in their membrane properties.ObjectivesTo investigate the effect of different pulse widths and directionalities of TMS on MEP latencies, motor thresholds and plastic aftereffects of rTMS.MethodsUsing a controllable pulse stimulator TMS (cTMS), we stimulated fifteen subjects with quasi-unidirectional TMS pulses of different pulse durations (40 μs, 80 μs and 120 μs) and determined thresholds and MEP AP latencies. We then compared the effects of 80 μs quasi-unidirectional pulses to those of 80 μs pulses with different pulse directionality characteristics (0.6 and 1.0 M ratios). We applied 900 pulses of the selected pulse shapes at 1 Hz.ResultsThe aftereffects of 1 Hz rTMS depended on pulse shape and duration. 40 and 80 μs wide unidirectional pulses induced inhibition, 120 μs wide pulses caused excitation. Bidirectional pulses induced inhibition during the stimulation but had facilitatory aftereffects. Narrower pulse shapes caused longer latencies and higher resting motor thresholds (RMT) as compared to wider pulse shapes.ConclusionsWe can tune the aftereffects of rTMS by manipulating pulse width and directionality; this may be due to the different membrane properties of the various neuronal segments such as dendrites.SignificanceTo date, rTMS frequency has been the main determinant of the plastic aftereffects. However, we showed that pulse width also plays a major role, probably by recruiting novel neuronal targets. 相似文献
8.
Objective
To evaluate the importance of the distance between stimulation electrodes, in various montages, on the ability to induce sustained cortical excitability changes using transcranial direct and random noise stimulation.Methods
Twelve healthy subjects participated in four different experimental conditions. The stimulation electrode was always placed over the primary motor cortex; the reference electrode was placed at the contralateral orbit or at the ipsilateral/contralateral arm. MEPs were recorded in order to measure changes in cortical excitability over time.Results
The distance between the two electrodes correlates negatively with the duration and magnitude of induced after-effects.Conclusions
In particular when using extracephalic reference electrodes with transcranial electric stimulation techniques, the stimulation intensity has to be adapted to account for interelectrode distance.Significance
Electrode distance plays a critical role in the induction for stimulation after-effects in tDCS and tRNS studies, and must be taken into account in future studies and also when making comparisons with the published literature. 相似文献9.
Yoshiko Shibuta Yoshimitsu Shimatani Hiroyuki Nodera Yuishin IzumiRyuji Kaji 《Clinical neurophysiology》2013,124(10):2046-2053
Objective
Amyotrophic lateral sclerosis (ALS) is characterised by the increased excitability of motoneurons and heterogeneous loss of axons. The heterogeneous nature of the disease process among fibres may show variability of excitability in ALS.Methods
Multiple nerve excitability tests were performed in 28 ALS patients and 23 control subjects, by tracking at the varying threshold levels (10%, 20%, 40% and 60% of maximum amplitudes).Results
In normal controls, excitability measures at low target levels have the following characteristics compared to those at high target levels: longer strength–duration time constant, greater threshold reduction during depolarising currents and smaller threshold increase to hyperpolarising currents. ALS patients had less clear amplitude dependency of the parameters than the controls, indicating variability of axonal excitability. Three ALS patients demonstrated greater target-amplitude-dependent threshold changes in threshold electrotonus than controls, suggesting selective axonal hyperexcitability.Conclusions
Some of the ALS patients had variable axonal excitability at different target amplitudes, suggesting preferential hyperexcitability in the axons with low target amplitude levels.Significance
Variable membrane potentials of motor axons in ALS may be assessed by recording excitability testing at different target amplitude levels. 相似文献10.
Maria-Ioanna Stefanou Debora Desideri Justus Marquetand Paolo Belardinelli Christoph Zrenner Holger Lerche Ulf Ziemann 《Clinical neurophysiology》2017,128(12):2503-2509
Objective
Mutations in STX1B encoding the presynaptic protein syntaxin-1B are associated with febrile seizures with or without epilepsy. It is unclear to what extent these mutations are linked to abnormalities of cortical glutamatergic or GABAergic neurotransmission. We explored this question using single- and paired-pulse transcranial magnetic stimulation (TMS) excitability markers.Methods
We studied nine currently asymptomatic adult STX1B mutation carriers with history of epilepsy and febrile seizures, who had been seizure-free for at least eight years without antiepileptic drug treatment, and ten healthy age-matched controls. Resting motor threshold (RMT), and input-output curves of motor evoked potential (MEP) amplitude, short-interval intracortical inhibition (SICI, marker of GABAAergic excitability) and intracortical facilitation (ICF, marker of glutamatergic excitability) were tested.Results
RMT, and input-output curves of MEP amplitude, SICI and ICF revealed no significant differences between STX1B mutation carriers and healthy controls.Conclusions
Findings suggest normal motor cortical GABAAergic and glutamatergic excitability in currently asymptomatic STX1B mutation carriers.Significance
TMS measures of motor cortical excitability show utility in demonstrating normal excitability in adult STX1B mutation carriers with history of seizures. 相似文献11.
Objective
Neuromuscular electrical stimulation that incorporates wide pulse widths (1 ms) and high frequencies (100 Hz; wide pulse-NMES (WP-NMES)) augments contractions through an increased reflexive recruitment of motoneurons in individuals without neurological impairments and those with spinal cord injury. The current study was designed to investigate whether WP-NMES also augments contractions after stroke. We hypothesized that WP-NMES would generate larger contractions in the paretic arm compared to the non-paretic arm due to increased reflex excitability for paretic muscles after stroke.Methods
The biceps brachii muscles were stimulated bilaterally in 10 individuals with chronic hemiparetic stroke. Four stimulation patterns were delivered to explore the effects of pulse width and frequency on contraction amplitude: 20–100–20 Hz (4 s each phase, 1 ms pulse width); 20–100–20 Hz (4 s each phase, 0.1 ms); 20 Hz for 12 s (1 ms); and 100 Hz for 12 s (1 ms). Elbow flexion torque and electromyography were recorded.Results
Stimulation that incorporated 1 ms pulses evoked more torque in the paretic arm than the non-paretic arm. When 0.1 ms pulses were used there was no difference in torque between arms. For both arms, torque declined significantly during the constant frequency 100 Hz stimulation and did not change during the constant frequency 20 Hz stimulation.Conclusions
The larger contractions generated by WP-NMES are likely due to increased reflexive recruitment of motoneurons, resulting from increased reflex excitability on the paretic side.Significance
NMES that elicits larger contractions may allow for development of more effective stroke rehabilitation paradigms and functional neural prostheses. 相似文献12.
Nicolás M. Phielipp Utpal Saha Tejas Sankar Akihiro Yugeta Robert Chen 《Clinical neurophysiology》2017,128(6):1109-1115
Objective
To evaluate the safety of repetitive transcranial magnetic stimulation (rTMS) in patients with implanted subdural cortical electrodes.Methods
We performed ex-vivo experiments to test the temperature, displacement and current induced in the electrodes with single pulse transcranial magnetic stimulation (TMS) from 10 to 100% of stimulator output and tested a typical rTMS protocol used in a clinical setting. We then used rTMS to the motor cortex to treat a patient with refractory post-herpetic neuralgia who had previously been implanted with a subdural motor cortical electrode for pain management. The rTMS protocol consisted of ten sessions of 2000 stimuli at 20 Hz and 90% of resting motor threshold.Results
The ex-vivo study showed an increase in the coil temperature of 2 °C, a maximum induced charge density of 30.4 μC/cm2/phase, and no electrode displacement with TMS. There was no serious adverse effect associated with rTMS treatment of the patient. Cortical tremor was observed in the intervals between trains of stimuli during one treatment session.Conclusions
TMS was safe in a patient with implanted Medtronic Resume II electrode (model 3587A) subdural cortical electrode.Significance
TMS may be used as a therapeutic, diagnostic or research tool in patients this type of with implanted cortical electrodes. 相似文献13.
Michele Dileone Laura Mordillo-Mateos Antonio Oliviero Guglielmo Foffani 《Brain stimulation》2018,11(4):676-688
Background
Transcranial static magnetic field stimulation (tSMS) was recently added to the family of inhibitory non-invasive brain stimulation techniques. However, the application of tSMS for 10–20?min over the motor cortex (M1) induces only short-lasting effects that revert within few minutes.Objective
We examined whether increasing the duration of tSMS to 30?min leads to long-lasting changes in cortical excitability, which is critical for translating tSMS toward clinical applications.Methods
The study comprised 5 experiments in 45 healthy subjects. We assessed the impact of 30-min-tSMS over M1 on corticospinal excitability, as measured by the amplitude of motor evoked potentials (MEPs) and resting motor thresholds (RMTs) to single-pulse transcranial magnetic stimulation (TMS) (experiments 1–2). We then assessed the impact of 30-min-tSMS on intracortical excitability, as measured by short-interval intracortical facilitation (SICF) and short-interval intracortical inhibition (SICI) using paired-pulse TMS protocols (experiments 2–4). We finally assessed the impact of 10-min-tSMS on SICF and SICI (experiment 5).Results
30-min-tSMS decreased MEP amplitude compared to sham for at least 30?min after the end of the stimulation. This long-lasting effect was associated with increased SICF and reduced SICI. 10-min-tSMS –previously reported to induce a short-lasting decrease in MEP amplitude– produced the opposite changes in intracortical excitability, decreasing SICF while increasing SICI.Conclusions
These results suggest a dissociation of intracortical changes in the consolidation from short-lasting to long-lasting decrease of corticospinal excitability induced by tSMS. The long-lasting effects of 30-min-tSMS open the way to the translation of this simple, portable and low-cost technique toward clinical trials. 相似文献14.
Eugen Gallasch Dietmar Rafolt Magdalena Postruznik Shane Fresnoza Monica Christova 《Clinical neurophysiology》2018,129(7):1397-1402
Objectives
Rotation of a static magnet over the motor cortex (MC) generates a transcranial alternating magnetic field (tAMF), and a linked alternating electrical field. The aim of this transcranial magnetic stimulation (TMS) study is to investigate whether such fields are able to influence MC excitability, and whether there are parallels to tACS induced effects.Methods
Fourteen healthy volunteers received 20?Hz tAMF stimulation over the MC, over the vertex, and 20?Hz tACS over the MC, each with a duration of 15?min. TMS assessments were performed before and after the interventions. Changes in motor evoked potentials (MEP), short interval intra-cortical inhibition (SICI) and intra-cortical facilitation (ICF) were evaluated.Results
The tACS and the tAMF stimulation over the MC affected cortical excitability in a different way. After tAMF stimulation MEP amplitudes and ICF decreased and the effect of SICI increased. After tACS MEP amplitudes increased and there were no effects on SICI and ICF.Conclusions
The recorded single and paired pulse MEPs indicate a general decrease of MC excitability following 15 min of tAMF stimulation.Significance
The effects demonstrate that devices based on rotating magnets are potentially suited to become a novel brain stimulation tool in clinical neurophysiology. 相似文献15.
Utako Takechi Kaoru Matsunaga Ryoji Nakanishi Hiroaki Yamanaga Nobuki Murayama Kosuke Mafune Sadatoshi Tsuji 《Clinical neurophysiology》2014,125(10):2055-2069
Objective
A general lack of longitudinal studies on interhemispheric interactions following stroke led us to use transcranial magnetic stimulation (TMS) to examine changes in corticospinal/intracortical excitability and transcallosal inhibition over a 1-year period following subcortical stroke.Methods
We measured TMS parameters such as motor threshold (MT), short-interval intracortical inhibition (SICI), and ipsilateral silent period (iSP) and evaluated clinical scores at three time-points (T1, T2, and T3) in 24 patients and 25 age-matched healthy subjects.Results
At T1, we observed reduced MTs and SICIs with prolonged iSPs in the unaffected hemisphere (UH). In contrast, increased MTs and reduced SICIs were observed in the affected hemisphere (AH). These abnormalities gradually reduced and no MEP response to TMS at T1 predicted a worse prognosis. The prolonged iSP at T1 was associated with more severe impairments, but it did not necessarily predict a worse prognosis after 1 year.Conclusions
UH excitability was increased at the post-acute time-period, which may have resulted in enhanced transcallosal inhibition to the AH. However, it is unclear whether there was a causal relationship between the enhanced transcallosal inhibition and the extent of clinical recovery.Significance
This is the first study to demonstrate changes in transcallosal inhibition over a longitudinal period following stroke. 相似文献16.
Kawasaki Y Fujiki M Ooba H Sugita K Hikawa T Abe T Ishii K Kobayashi H 《Clinical neurology and neurosurgery》2012,114(7):976-980
Objective
To evaluate the cortical excitability in patients with mild cortical compression.Methods
The present study used short interval intracortical inhibition (SICI), intracortical facilitation (ICF), and short latency afferent inhibition (SAI) to evaluate motor cortex excitability in 16 chronic subdural hematoma (CSDH) patients with memory impairment and compared the data with those of 16 healthy controls.Results
SAI was reduced in patients compared with controls (99 ± 14 vs. 47 ± 11% of the test size; p < 0.0001, unpaired t-test). CSDH patients tended to have a high resting motor threshold and less pronounced SICI and ICF than controls, but these differences were not significant. Treatment of hematoma improved memory impairment and SAI in CSDH patients with wide individual variations that ranged from an increase of 74% to 17% of test size.Conclusion
These findings suggest that measuring SAI may provide a means of probing the integrity of cortical cholinergic networks in a compressed human brain. 相似文献17.
Kristina Laaksonen Erika Kirveskari Jyrki P. Mäkelä Markku Kaste Satu Mustanoja Lauri Nummenmaa Turgut Tatlisumak Nina Forss 《Clinical neurophysiology》2012,123(12):2429-2436
Objective
Afferent input is proposed to mediate its effect on motor functions by modulating the excitability of the motor cortex. We aimed to clarify – in a longitudinal study – how afferent input affects motor cortex excitability after stroke and how it is associated with recovery of hand function.Methods
The motor cortex excitability was studied by measuring the reactivity of the motor cortex beta rhythm to somatosensory stimulation. We recorded the amplitude of the suppression and subsequent rebound of the beta oscillations during tactile finger stimulation with MEG in 23 first-ever stroke patients within one week and at 1 and 3 months after stroke, with concomitant evaluation of hand function.Results
The strength of the beta rhythm rebound, suggested to reflect decreased motor cortex excitability, was weak in the affected hemisphere after stroke and it was subsequently increased during recovery. The rebound strength correlated with hand function tests in all recordings.Conclusion
Motor cortex excitability is modulated by afferent input after stroke. The motor cortex excitability is increased in the AH acutely after stroke and decreases in parallel with recovery of hand function.Significance
The results implicate the importance of parallel recovery of both sensory and motor systems in functional recovery after stroke. 相似文献18.
Raffaele Nardone Viviana Versace Luca Sebastianelli Francesco Brigo Stefan Golaszewski Monica Christova Eugen Gallasch Leopold Saltuari Eugen Trinka 《Clinical neurophysiology》2017,128(10):1971-1977
Objective
There is increasing evidence that an involvement of central nervous system (CNS) can occur in several myopathies. Transcranial magnetic stimulation (TMS) may represent a valuable tool for investigating important neurophysiological and pathophysiological aspects of cortical involvement in neuromuscular disorders. In this review paper we aimed to perform a systematic search of the studies employing TMS techniques in subjects suffering from myopathies.Methods
A literature search was conducted using PubMed and Embase. We identified and reviewed 9 articles matching the inclusion criteria. One hundred twenty patients were included in these studies, which have applied TMS in patients with muscle disorders.Results
To date, a few studies using TMS have been performed in myopathic patients and detected subclinical abnormalities in cortical reactivity and plasticity. The most consistent finding was a decrease in intracortical inhibition, which likely represents a non-specific compensatory mechanism of the CNS in an attempt to overcome the muscle deficit through an increase of the motor cortex output to deficient muscles.Conclusions
Application of TMS to characterize the pathophysiology of the CNS in these subjects appears to be safe and may lead to the development of valuable biomarkers. Well-defined motor cortical excitability patterns can be identified in the different muscle diseases, even if preliminary findings should be confirmed in future studies in larger cohorts of patients.Significance
TMS studies may shed new light on the physiological and pathophysiological mechanisms underlying the cortical involvement in muscle disorders. 相似文献19.
Tamara Gedankien Peter J. Fried Alvaro Pascual-Leone Mouhsin M. Shafi 《Clinical neurophysiology》2017,128(12):2419-2427
Objective
We studied the correlation between motor evoked potentials (MEPs) and early TMS-evoked EEG potentials (TEPs) from single-pulse TMS before and after intermittent Theta Burst Stimulation (iTBS) to the left primary motor cortex (M1) in 17 healthy older participants.Methods
TMS was targeted to the hand region of M1 using a MRI-guided navigated brain stimulation system and a figure-of-eight biphasic coil. MEPs were recorded from the right first dorsal interosseous muscle using surface EMG. TEPs were extracted from a 61-channel EEG recording. Participants received 90 single TMS pulses at 120% of resting motor threshold before and after iTBS.Results
Across all participants, the change in N15-P30 TEP and MEP amplitudes were significantly correlated (r = 0.69; p < 0.01). Average TEP responses did not change significantly after iTBS, whereas MEP amplitudes showed a significant increase.Conclusions
Changes in corticospinal reactivity and cortical reactivity induced by iTBS are related. However, the effect of iTBS on TEPs, unlike MEPs, is not straightforward.Significance
Our findings help elucidate the relationship between changes in cortical and corticospinal excitability in healthy older individuals. Going forward, TEPs may be used to evaluate the effects of theta-burst stimulation in non-motor brain regions. 相似文献20.
Thomas Gregor Issac S. R. Chandra B. C. Nagaraju 《Annals of Indian Academy of Neurology》2013,16(4):619-622