About this Research Topic
Transcranial magnetic stimulation (TMS) is gaining popularity as a non-invasive, painless method to activate specific cortical areas and sensory-motor circuits and facilitate plastic changes in these neural networks of the central nervous system. Recently, TMS has been suggested by the International Federation of Clinical Neurophysiology to treat neurological and psychiatric disorders.
Even though a lot of research reports have indicated the benefits of TMS in patients, the neural modulation mechanisms induced by TMS to promote neural repair and restoration still remain unclear. Based on the theory of neural development and functional reconstruction, researchers started to focus on motor training combined with task-based neural circuit re-construction upon TMS treatment. The evaluation of TMS-linked circuit re-construction has predominantly been performed using electrophysiology, imaging (fMRI) and neural tracking technology in animals and humans. Animal experiments have shown that magnetic stimulation after spinal cord injury (SCI) can protect spinal nerve tissue and promote the regeneration of nerve fibers to achieve nerve reinnervation of the damaged limbs. Recently, Christiansen and Perez demonstrated that using a targeted TMS protocol based on the principle of spike-timing dependent plasticity could induce plasticity of residual corticospinal projections and spontaneously increase motor output in patients with chronic incomplete SCI, thus enhancing motor function. However, in the context of neural function in humans, we need to apply technologies that are more sensitive to real-time cortical activities, such as functional near-infrared spectroscopy (fNIRS). For example, Rihui Li and colleagues applied fNIRS to investigate the alterations in hemodynamic responses and cortical connectivity patterns that are induced by high-frequency rTMS at a sub-threshold intensity. Results suggested that fNIRS imaging provided a reliable measure of regional cortical brain activation that advances our understanding of the manner in which sub-threshold rTMS affects cortical excitability and brain connectivity.
Nowadays, fNIRS offers an alternative way to estimate TMS activity-linked changes in tissue hemoglobin (Hb) concentration based on the different absorption coefficients for oxygenated versus deoxygenated hemoglobin. Furthermore, as an emerging noninvasive optical imaging technique, fNIRS holds several advantages over other imaging modalities: a high signal-to-noise ratio, non-interference with electromagnetic fields, portability, and reduced sensitivity to motion artifacts. These features make fNIRS a promising tool to investigate the cortical activation and connectivity associated with TMS.
This Research Topic aims to provide an inter- and multi-disciplinary overview of the research in the field of neural circuits modulation with TMS or derived models such as non-transcranial functional stimulation in motor rehabilitation. This topic will focus on neural circuit re-construction and neural plasticity following TMS modulation with a particular focus on novel technologies that allow for a more precise spatiotemporal resolution of cortical activity changes.
We also encourage article submissions on clinical trials and clinical applications of TMS as compared to traditional rehabilitation techniques. We welcome original research articles, reviews, protocols and case reports. The aim of the topic is to explore the mechanism of neural circuits modulation and develop methods for functional recovery with TMS in animal models and humans.
Keywords: TMS, movement disorders, neural plasticity, Neural circuits, Neural network