Repeated transcranial magnetic stimulation (rTMS) is one of the commonly used brain stimulation techniques. In order to investigate the effects of rTMS on the excitability of different types of neurons, this study is conducted to investigate the effects of rTMS on the cognitive function of mice and the excitability of hippocampal glutaminergic neurons and gamma-aminobutyric neurons from the perspective of electrophysiology. In this study, mice were randomly divided into glutaminergic control group, glutaminergic magnetic stimulation group, gamma-aminobutyric acid energy control group, and gamma-aminobutyric acid magnetic stimulation group. The four groups of mice were injected with adeno-associated virus to label two types of neurons and were implanted optical fiber. The stimulation groups received 14 days of stimulation and the control groups received 14 days of pseudo-stimulation. The fluorescence intensity of calcium ions in mice was recorded by optical fiber system. Behavioral experiments were conducted to explore the changes of cognitive function in mice. The patch-clamp system was used to detect the changes of neuronal action potential characteristics. The results showed that rTMS significantly improved the cognitive function of mice, increased the amplitude of calcium fluorescence of glutamergic neurons and gamma-aminobutyric neurons in the hippocampus, and enhanced the action potential related indexes of glutamergic neurons and gamma-aminobutyric neurons. The results suggest that rTMS can improve the cognitive ability of mice by enhancing the excitability of hippocampal glutaminergic neurons and gamma-aminobutyric neurons.
In recent years, the ongoing development of transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) has demonstrated significant potential in the treatment and rehabilitation of various brain diseases. In particular, the combined application of TES and TMS has shown considerable clinical value due to their potential synergistic effects. This paper first systematically reviews the mechanisms underlying TES and TMS, highlighting their respective advantages and limitations. Subsequently, the potential mechanisms of transcranial electromagnetic combined stimulation are explored, with a particular focus on three combined stimulation protocols: Repetitive TMS (rTMS) with transcranial direct current stimulation (tDCS), rTMS with transcranial alternating current stimulation (tACS), and theta burst TMS (TBS) with tACS, as well as their clinical applications in brain diseases. Finally, the paper analyzes the key challenges in transcranial electromagnetic combined stimulation research and outlines its future development directions. The aim of this paper is to provide a reference for the optimization and application of transcranial electromagnetic combined stimulation schemes in the treatment and rehabilitation of brain diseases.
Transcranial magnetic stimulation (TMS) combined with electroencephalography(EEG) has become an important tool in brain research. However, it is difficult to remove the large artifacts in EEG signals caused by the online TMS intervention. In this paper, we summed up various types of artifacts. After introducing a variety of online methods, the paper emphasized on offline approaches, such as subtraction, principal component analysis and independent component analysis, which can remove or minimize TMS-induced artifacts according to their different characteristics. Although these approaches can deal with most of the artifacts induced by TMS, the removal of large artifacts still needs to be improved. This paper systematically summarizes the effective methods for artifacts removal in TMS-EEG studies. It is a good reference for TMS-EEG researchers while choosing the suitable artifacts removal methods.
ObjectiveTo observe the efficacy of high-frequency repetitive transcranial magnetic stimulation (rTMS) applied at contralesional hemisphere Broca’s homologue on patients with global aphasia after left massive cerebral infarction. Methods Patients with global aphasia after left massive cerebral infarction in the Department of Neurorehabilitation of China Rehabilitation Research Center between August 2021 and December 2023 were selected. According to the random number table method, patients were randomly divided into a low-frequency rTMS group and a high-frequency rTMS group. rTMS targeted the mirror area within the right hemispheric Broca’s area. Patients’ language ability was assessed pre- and post-treatment by the Chinese version of the western aphasia battery (WAB). Results A total of 27 patients were included, with 14 in the low-frequency rTMS group and 13 in the high-frequency rTMS group. Before treatment, there was no statistically significant difference in the WAB test indicators between the two groups of patients (P>0.05). After treatment, WAB scores (spontaneous speech, auditory comprehension, naming, repetition, aphasia quotients) in both groups were significantly improved (P<0.05); compared to the low-frequency rTMS group, the high-frequency rTMS group exhibited significant improvement in spontaneous speech, auditory comprehension, repetition, naming and aphasia quotients (P<0.05). Conclusion The effect of high-frequency rTMS excitation to contralesional hemisphere is better than that of conventional low-frequency rTMS inhibition to contralesional hemisphere in improving the speech function of patients with global aphasia after left massive cerebral infarction.
Transcranial magnetic stimulation (TMS), a widely used neuroregulatory technique, has been proven to be effective in treating neurological and psychiatric disorders. The therapeutic effect is closely related to the intracranial electric field caused by TMS, thus accurate measurement of the intracranial electric field generated by TMS is of great significance. However, direct intracranial measurement in human brain faces various technical, safety, ethical and other limitations. Therefore, we have constructed a brain phantom that can simulate the electrical conductivity and anatomical structure of the real brain, in order to replace the clinical trial to achieve intracranial electric field measurement. We selected and prepared suitable conductive materials based on the electrical conductivity of various layers of the real brain tissue, and performed image segmentation, three-dimensional reconstruction and three-dimensional printing processes on each layer of tissue based on magnetic resonance images. The production of each layer of tissue in the brain phantom was completed, and each layer of tissue was combined to form a complete brain phantom. The induced electric field generated by the TMS coil applied to the brain phantom was measured to further verify the conductivity of the brain phantom. Our study provides an effective experimental tool for studying the distribution of intracranial electric fields caused by TMS.
In transcranial magnetic stimulation (TMS), the conductivity of brain tissue is obtained by using diffusion tensor imaging (DTI) data processing. However, the specific impact of different processing methods on the induced electric field in the tissue has not been thoroughly studied. In this paper, we first used magnetic resonance image (MRI) data to create a three-dimensional head model, and then estimated the conductivity of gray matter (GM) and white matter (WM) using four conductivity models, namely scalar (SC), direct mapping (DM), volume normalization (VN) and average conductivity (MC), respectively. Isotropic empirical conductivity values were used for the conductivity of other tissues such as the scalp, skull, and cerebrospinal fluid (CSF), and then the TMS simulations were performed when the coil was parallel and perpendicular to the gyrus of the target. When the coil was perpendicular to the gyrus where the target was located, it was easy to get the maximum electric field in the head model. The maximum electric field in the DM model was 45.66% higher than that in the SC model. The results showed that the conductivity component along the electric field direction of which conductivity model was smaller in TMS, the induced electric field in the corresponding domain corresponding to the conductivity model was larger. This study has guiding significance for TMS precise stimulation.
Currently, transcranial magnetic stimulation (TMS) has been widely used in the treatment of depression, Parkinson’s disease and other neurological diseases. To be able to monitor the brain’s internal activity during TMS in real time and achieve better treatment outcomes, the researchers proposed combining TMS with neuroimaging methods such as magnetic resonance imaging (MRI), both of which use Tesla-level magnetic fields. However, the combination of strong current, large magnetic field and small size is likely to bring physical concerns which can lead to mechanical and thermal instability. In this paper, the MRI static magnetic field, the TMS coil and human head model were built according to the actual situations. Through the coupling of the magnetic field and the heat transfer module in the finite element simulation software COMSOL, the force and temperature of the TMS coil and head were obtained when the TMS was used in combination with MRI (TMS-MRI technology). The results showed that in a 3 T MRI environment, the maximum force density on the coil could reach 2.51 × 109 N/m3. Both the direction of the external magnetic field and the current direction in the coil affected the force distributions. The closer to the boundary of the external magnetic field, the greater the force. The magnetic field generated by the coil during TMS treatment increased the temperature of the brain tissue by about 0.16 °C, and the presence of the MRI static magnetic field did not cause additional thermal effects. The results of this paper can provide a reference for the development of the use guidelines and safety guidelines of TMS-MRI technology.
Existing neuroregulatory techniques can achieve precise stimulation of the whole brain or cortex, but high-focus deep brain stimulation has been a technical bottleneck in this field. In this paper, based on the theory of negative permeability emerged in recent years, a simulation model of magnetic replicator is established to study the distribution of the induced electric field in the deep brain and explore the possibility of deep focusing, which is compared with the traditional magnetic stimulation method. Simulation results show that a single magnetic replicator realized remote magnetic source. Under the condition of the same position and compared with the traditional method of stimulating, the former generated smaller induced electric field which sharply reduced with distance. By superposition of the magnetic field replicator, the induced electric field intensity could be increased and the focus could be improved, reducing the number of peripheral wires while guaranteeing good focus. The magnetic replicator model established in this paper provides a new idea for precise deep brain stimulation, which can be combined with neuroregulatory techniques in the future to lay a foundation for clinical application.
Objective To evaluate the systematic reviews of repetitive transcranial magnetic stimulation (rTMS) for insomnia, to provide supporting evidence for clinical practice. Methods PubMed, Embase, Web of Science, Cochrane Library, Elsevier Science Direct, China National Knowledge Infrastructure, SinoMed, Wanfang and Chongqing VIP were searched from databases establishment to May 30, 2022, to find systematic reviews on the treatment of insomnia with rTMS as the main method. The methodological quality, reporting quality and evidence quality of outcome indicators were evaluated by AMSTAR 2, PRISMA 2020 and GRADE. Results A total of 4 systematic reviews published between 2018 and 2021 were included. Further analysis showed that one of the systematic reviews had a low AMSTAR 2 quality rating and the remaining systematic reviews were very low. The average PRISMA 2020 score of these 4 systematic reviews was (20.75±3.27) points, of which 3 systematic reviews had some defects in their reports, and the other one had relatively complete reports. The GRADE evidence quality assessment showed that there were 40 outcome indicators in the included literature, of which 3 outcome indicators (sleep quality, the percentage of S2 sleep in total sleep time, and S3 sleep in percentage of total sleep time) were rated as moderate, 17 were rated as low and 20 were rated as very low. Conclusions The treatment of insomnia by rTMS has achieved certain effects in clinical practice, but the systematic review of rTMS as the main intervention measure for insomnia needs to further improve the quality and standardize related research. The clinical application of rTMS for insomnia should be treated as appropriate.
Weightlessness in the space environment affects astronauts’ learning memory and cognitive function. Repetitive transcranial magnetic stimulation has been shown to be effective in improving cognitive dysfunction. In this study, we investigated the effects of repetitive transcranial magnetic stimulation on neural excitability and ion channels in simulated weightlessness mice from a neurophysiological perspective. Young C57 mice were divided into control, hindlimb unloading and magnetic stimulation groups. The mice in the hindlimb unloading and magnetic stimulation groups were treated with hindlimb unloading for 14 days to establish a simulated weightlessness model, while the mice in the magnetic stimulation group were subjected to 14 days of repetitive transcranial magnetic stimulation. Using isolated brain slice patch clamp experiments, the relevant indexes of action potential and the kinetic property changes of voltage-gated sodium and potassium channels were detected to analyze the excitability of neurons and their ion channel mechanisms. The results showed that the behavioral cognitive ability and neuronal excitability of the mice decreased significantly with hindlimb unloading. Repetitive transcranial magnetic stimulation could significantly improve the cognitive impairment and neuroelectrophysiological indexes of the hindlimb unloading mice. Repetitive transcranial magnetic stimulation may change the activation, inactivation and reactivation process of sodium and potassium ion channels by promoting sodium ion outflow and inhibiting potassium ion, and affect the dynamic characteristics of ion channels, so as to enhance the excitability of single neurons and improve the cognitive damage and spatial memory ability of hindlimb unloading mice.