Standardized Induction and Assessment of Long-term Potentiation-like Cortical Plasticity Using Transcranial Magnetic Stimulation

Summary

This paper describes the standardized induction of Long-term Potentiation-like cortical plasticity using repetitive stimulation protocols, followed by applying single-pulse transcranial magnetic stimulation guided by a neuronavigation system to evaluate synaptic plasticity.

Abstract

In recent years, transcranial magnetic stimulation (TMS) has emerged as a non-invasive, low-cost, and effective technique for assessing synaptic changes in the brain. Synaptic plasticity is a fundamental mechanism of neural plasticity that reflects the brain's ability to modify the strength and efficacy of synaptic connections in response to experience or environmental stimuli. Long-term potentiation (LTP) serves as the predominant experimental model for studying synaptic plasticity mechanisms, playing a critical role in understanding synaptic plasticity and overall brain function. Specific stimulation patterns, especially repetitive or burst patterns of pulses such as intermittent theta burst stimulation (iTBS), could induce LTP-like cortical plasticity, providing a feasible non-invasive approach to evaluate synaptic plasticity. However, the application of these techniques requires strict adherence to standardized protocols to ensure the accuracy and reliability of the results. Therefore, this article aims to demonstrate a standardized approach for inducing LTP-like plasticity using iTBS, followed by assessment of synaptic plasticity with single-pulse TMS, with both procedures guided by a neuronavigation system. The focus of this article will be on the essential technical procedures and operational considerations necessary to achieve precise and reliable measurements of cortical plasticity.

Introduction

In recent years, transcranial magnetic stimulation (TMS) has emerged as a non-invasive, cost-effective, and efficient technique for probing and modulating neural activity in the human brain¹. Among various stimulation paradigms, intermittent theta burst stimulation (iTBS) has attracted significant attention for its ability to induce long-term potentiation (LTP)-like plasticity in the human motor cortex². Specifically, iTBS delivers high-frequency bursts at theta intervals, mimicking endogenous theta-gamma coupling patterns associated with synaptic plasticity³. It induces LTP-like plasticity by act....

Protocol

The Ethics Committee of the First Affiliated Hospital with Nanjing Medical University approved the protocols (number 2023-SR-789), and the protocol was registered with the Chinese Clinical Trial Registry (number ChiCTR2400082549). All procedures were conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained prior to enrollment in the study.

1. Consent process

1. Prior to any assessment, explain the aim(s) of the assessment, the main experimental procedures, and any potential risk factors associated with the study. Answer any questions or concerns. Request acknowledgment of the consent process a....

Results

During the demonstration, a neuronavigation system was used to guide the accurate positioning of the TMS coil over the motor hotspot, providing real-time spatial feedback and minimizing coil-placement variability. A TMS device (figure-of-eight coil, 70 mm) delivered stimulation throughout the session. To illustrate the procedure, representative results from one participant are presented below. The recorded MEP amplitudes exhibited stable and consistent responses across single-pulse trials, reflecting the stability provid.......

Discussion

The application of TMS to investigate synaptic plasticity has great potential for advancing neurophysiological research. Specifically, single-pulse TMS can be used to assess LTP-like plasticity, while rTMS offers a practical, non-invasive method for inducing it. However, the accuracy and reproducibility of these findings depend heavily on the standardization of procedural parameters. Accordingly, this protocol provides a reliable and standardized approach for assessing LTP-like plasticity using TMS guided by a neuronavig.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
70 mm TMS coil	Yiruide Co., Wuhan, China
Electromyography surface electrodes	Cathay, Shanghai, China	CM25R
Electromyography system	Yiruide Co., Wuhan, China
Neuronavigation pointer	ANT Neuro, Germany
Neuronavigation reflective markers	ANT Neuro, Germany
Neuronavigation system	ANT Neuro, Germany	Visor2, version 2.5.3.50294
TMS stimulator	Yiruide Co., Wuhan, China	NS5000