Background
The premotor cortex plays a role in the planning of movement. Previous transcranial magnetic stimulation (TMS) studies have shown ipsilateral premotor-to-motor inhibition in healthy subjects at rest. Moreover, this premotor-to-motor inhibition has been found to be modulated during preparation for movement, such as precision grip and whole hand grasp. Cooperation between the bilateral ventral premotor cortices may play a functional role. We aimed to investigate the influence of the contralateral on the ipsilateral ventral premotor cortex.
Methods
Fourteen right-handed healthy subjects (six women and eight men; mean age, 37 years; standard deviation, 14 years) completed the study. We used a three single-pulse TMS paradigm (preconditioning, conditioning and test pulse) to sequentially stimulate the right ventral premotor cortex, left ventral premotor cortex and left primary motor cortex.
Results
We found that in healthy subjects at rest, stimulating the contralateral ventral premotor cortex resulted in reversal of the resting premotor-to-motor inhibition.
Conclusions
Our results suggest that the contralateral ventral premotor cortex exerts an inhibitory influence on the ipsilateral ventral premotor cortex, which may be a component of bi-hemispheric control of manual tasks. This is the first study to evaluate the functional connectivity between the bilateral ventral premotor cortices.

Noninvasive stimulation of the nervous system for treating chronic neuropathic pain has received attention because of its tolerability and relative efficacy. Repetitive transcranial magnetic stimulation (rTMS) is a representative method of noninvasive brain stimulation. Evidence-based guidelines on therapeutic use of rTMS have been proposed recently for several neurological diseases. These guidelines recommend treating neuropathic pain by applying high-frequency (≥ 5 Hz) rTMS to the primary motor cortex contralateral to the painful side. This review summarizes the mechanisms and guidelines of rTMS for treating neuropathic pain, and proposes directions for future research.

Citations

• Efficacy of repetitive transcranial magnetic stimulation for phantom limb pain- a meta analysis of randomized controlled trials
  FNU Chandni, FNU Savanti, Rohit Kumar, Murk Raj, Aakash Kumar, Aashish Kumar, Sejal Kinger, Sahil Kumar, Himat Rai, Afsana Ansari Shaik, Muhammad Sohaib Asghar
  Neurological Sciences.2025; 46(5): 2019.     CrossRef
• Impact of Titanium Skull Plate on Transcranial Magnetic Stimulation: Analysis of Induced Electric Fields
  Mai Lu, Shoogo Ueno
  Life.2024; 14(5): 642.     CrossRef
• Synaptic sensitization in the anterior cingulate cortex sustains the consciousness of pain via synchronized oscillating electromagnetic waves
  Richard Ambron
  Frontiers in Human Neuroscience.2024;[Epub]     CrossRef
• Dualism, Materialism, and the relationship between the brain and the mind in experiencing pain
  Richard Ambron
  Neuroscience.2024; 561: 139.     CrossRef

Transcranial magnetic stimulation (TMS) is a safe and noninvasive tool for investigating the cortical excitability of the human brain and the neurophysiological functions of GABAergic, glutamatergic, and cholinergic neural circuits. Neurophysiological biomarkers based on TMS parameters can provide information on the pathophysiology of dementia, and be used to diagnose Alzheimer’s disease and differentiate different types of dementia. This review introduces the basic principles of TMS, TMS devices and stimulating paradigms, several neurophysiological measurements, and the clinical implications of TMS for Alzheimer’s disease.

Citations

• Transcranial application of magnetic pulses for improving brain drug delivery efficiency via intranasal injection of magnetic nanoparticles
  Eunbi Ye, Eunkyoung Park, Eunseon Kim, Jung Eun Lee, Seung Ho Yang, Sung-Min Park
  Biomedical Engineering Letters.2023; 13(3): 417.     CrossRef
• Implantable acousto-optic window for monitoring ultrasound-mediated neuromodulation in vivo
  Sungho Lee, Keunhyung Lee, Myunghwan Choi, Jinhyoung Park
  Neurophotonics.2022;[Epub]     CrossRef
• Transcranial Magnetic Stimulation in the Treatment of Neurological Diseases
  Fahad A. Somaa, Tom A. de Graaf, Alexander T. Sack
  Frontiers in Neurology.2022;[Epub]     CrossRef

Background
Neuromodulation therapy has been used to an adjunctive treatment promoting motor recovery in stroke patients. The objective of the study was to determine the effect of repetitive transcranial magnetic stimulation (rTMS) on neurobehavioral recovery and evoked potentials in rats with middle cerebral artery occlusion. Methods: Seventy Sprague-Daley rats were induced permanent middle cerebral artery occlusion (MCAO) stroke model and successful stroke rats (n=56) assigned to the rTMS (n=28) and sham (n=28) group. The 10 Hz, high frequency rTMS gave on ipsilesional forepaw motor cortex during 2 weeks in rTMS group. The somatosensory evoked potential (SSEP) and motor evoked potential (MEP) were used to evaluate the electrophysiological changes. Behavioral function of the stroke rat was evaluated by the Rota rod and Garcia test. Results: Forty rats (NrTMS=20; Nsham=20) completed all experimental course. The rTMS group showed better performance than sham group in Rota rod test and Garcia test at day 11 (p<0.05) but not day 18 (p>0.05). The amplitude of MEP and SSEP in rTMS group was larger than sham group at day 18 (p<0.05). Conclusions: These data confirm that the high frequency rTMS on ipsilesional cerebral motor cortex can help the early recovery of motor performance in permanent middle cerebral artery stroke model and it may simultaneously associate with changes in neurophysiological activity in brain.

Citations

• A C-shaped miniaturized coil for transcranial magnetic stimulation in rodents
  Wenxuan Jiang, Robert Isenhart, Charles Y Liu, Dong Song
  Journal of Neural Engineering.2023; 20(2): 026022.     CrossRef
• Effects of high‐frequency repetitive transcranial magnetic stimulation (rTMS) on spontaneously hypertensive rats, an animal model of attention‐deficit/hyperactivity disorder
  Jungyun Kim, Heamen Park, Seong‐lan Yu, Sungju Jee, Keun‐Ah Cheon, Dong Ho Song, Seung Jun Kim, Woo‐Young Im, Jaeku Kang
  International Journal of Developmental Neuroscienc.2016; 53(1): 83.     CrossRef

Transcranial magnetic stimulation is a non-invasive, painless diagnostic tool of nervous propagation as well as of motor cortex excitability in healthy subjects and in patients affected by several neurological disease ie, stroke, epilepsy and multiple sclerosis etc. Motor areas can be reliably mapped and short-and long-term 'plastic' changes of neural connections can be studied and monitored over time. Recent studies suggest a therapeutic role of repetitive magnetic stimulation in neurologic and psychiatric disorders.

Mirror movements in adult is usually accompanied with various clinical syndromes. But the pathogenesis of mirror movement is not clearly understood. A 20-years old man visited with complaining of mirror movements in both hands, ophthalmoplegia and sensorineural hearing loss. He underwent through electromyography, transcranial magnetic stimulation, and functional magnetic resonance image. And we concluded that the mechanisms of his mirror movements were both ipsilateral innervated corticospinal tract and simultaneous activation of both motor cortex.

Purpose
MEPs elicited by transmagnetic stimulations of the motor cortex are facilitated by voluntary muscle contraction.We evaluated the effects of the imagination of the movements on latencies of MEPs and reciprocal inhibitionby using transmagnetic stimulations.Methods: Twenty two healthy volunteers(eight men and fourteen women) were studied. TMSs were delivered at restand during imagining abducting or adducting right thumb. A stimulator with a round coil and a fixed intensity of 80%of maximum was used to evoke MEPs. MEPs were evoked by magnetic stimulations over the scalp and cervicalspine(C7-T1), and central motor conduction times(CMCT) were calculated by subtracting the latency of compoundmuscle action potentials(CMAPs) obtained by stimulating over the cervical spine from that obtained by stimulating overthe scalp. The motor evoked potentials were recorded from right abductor pollicis brevis muscle(APB) and adductorpollicis muscle(AP) simultaneously.Results: Imagination of abduction resulted in a shortened latency of the CMAPs in APB, and a prolonged latency inAP. Imagination of adduction resulted in a shortened latency in AP, and a prolonged latency in APB. But the imaginationcaused no significant change in the latency of CMAPs elicited by stimulation over cervical spine. Therefore, thechanges of the CMCTs account for these latency changes with imagination of movement. With the imagination ofabduction, there are significant reduction of the CMCT

Background
It has been proposed that proprioceptive input can modulate neural excitability in both primary motor cortices (M1) simultaneously, although direct evidence for this is still lacking. Previous studies showed that proprioceptive accuracy of one hand is reduced after the application of one-Hz repetitive transcranial magnetic stimulation (rTMS) for 15 minutes over the contralateral somatosensory cortex. The aim of this study was to investigate the effect of rTMSinduced central proprioceptive deafferentation to excitability of both M1 as reflected in ipsilateral and contralateral motor evoked potentials (MEP).
Methods: MEPs of both abductor pollicis bravis (APB) muscles were recorded using single-pulse TMS over right M1 in seven healthy subjects. Immediately after one-Hz rTMS was applied for 15 minutes over the right somatosensory cortex, the MEP measurement was repeated. The proprioceptive function of the left thumb was assessed, before and after rTMS, using a position-matching task.
Results: There was an increase in ipsilateral MEP after the rTMS: whereas no MEPs were recorded on the ipsilateral hand before the rTMS, MEPs were recorded in both ipsilateral and contralateral hand in three of seven subjects. At the same time, the mean log amplitude was reduced and the mean latency was prolonged in the contralateral MEP.
Conclusions: rTMS-induced central proprioceptive deafferentation reduces the MEP generation in the contralateral hand, and fascilitates that in the ipsilateral hand. A further study with a larger sample seems warranted to confirm this finding and to elucidate the neurophysiology underlying it.

Transcranial magnetic stimulation (TMS) is a non-invasive tool used to study aspects of human brain physiology, includingmotor function and the pathophysiology of various brain disorders. A brief electric current passed through a magnetic coilproduces a high-intensity magnetic field, which can excite or inhibit the cerebral cortex. Although various brain regions canbe evaluated by TMS, most studies have focused on the motor cortex where motor evoked potentials (MEPs) are produced.Single-pulse and paired-pulse TMS can be used to measure the excitability of the motor cortex via various parameters, whilerepetitive TMS induces cortical plasticity via long-term potentiation or long-term depression-like mechanisms. Therefore,TMS is useful in the evaluation of physiological mechanisms of various neurological diseases, including movement disordersand epilepsy. In addition, it has diagnostic utility in spinal cord diseases, amyotrophic lateral sclerosis and demyelinatingdiseases. The therapeutic effects of repetitive TMS on stroke, Parkinson disease and focal hand dystonia are limited sincethe duration and clinical benefits seem to be temporary. New TMS techniques, which may improve clinical utility, are beingdeveloped to enhance clinical utilities in various neurological diseases.

Background
In the brain, the dominant primary motor cortex (M1) has a greater hand representation area, shows more profusehorizontal connections, and shows a greater reduction in intracortical inhibition after hand exercise than does the non-dominant M1,suggesting a hemispheric asymmetry in M1 plasticity. Methods: We performed a transcranial magnetic stimulation (TMS) study toinvestigate the hemispheric asymmetry of paired associative stimulation (PAS)-induced M1 plasticity in 9 right-handed volunteers.Motor evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) muscles of both hands, and MEP recruitmentcurves were measured at different stimulation intensities, before and after PAS. Results: MEP recruitment curves were significantlyenhanced in the dominant, but not the non-dominant M1. Conclusions: These results demonstrate that the dominant M1 has greaterPAS-induced plasticity than does the non-dominant M1. This provides neurophysiological evidence for the asymmetricalperformance of motor tasks related to handedness.