A revised calcium-dependent model of transcranial magnetic theta-burst stimulation

Calcium-dependent nonlinearity describes the after-effects of different patterns of theta-burst TMS

OBJECTIVE

Optimisation of transcranial magnetic stimulation protocol parameters can potentially improve their efficacy through theoretical mathematical models. This study aims to develop an elaborate but still parsimonious quantitative model for understanding the dosage-dependency of Theta-Burst Stimulation (TBS).

METHODS

We propose a calcium-dependent nonlinear model that uses Michaelis-Menten kinetics to represent competing molecular pathways in postsynaptic neurons during TBS intervention. The model integrates four subsystems: calcium dynamics, modulation substances, MEP learning, and metaplasticity, with a particular focus on the interaction between facilitatory and inhibitory signalling cascades.

RESULTS

Our model successfully reproduces experimental findings from various TBS protocols, including the reversal of after-effects observed in prolonged stimulation. The simulation results suggest that the competing molecular pathways with distinct calcium sensitivities and temporal dynamics determine the direction of after-effects.

CONCLUSIONS

This proposed model represents a substantial advancement in understanding TBS-induced neuromodulation by providing testable predictions for untested TBS protocols and offers complementary insights into the underlying neural mechanisms.

SIGNIFICANCE

This model offers a basic framework for potentially incorporating complex, nonlinear relationships between TBS parameters and after-effects under various neurological and psychiatric conditions. It also provides a valuable tool for later protocol optimisation and guiding future experimental designs.

Global research hotspots and trends of theta burst stimulation from 2004 to 2023: a bibliometric analysis

Background

Theta burst stimulation (TBS) has garnered widespread attention in the scientific community, but a comprehensive bibliometric analysis of TBS research remains absent. This study aims to fill this gap by elucidating the characteristics, hotspots, and trends in TBS publications over the past 20 years using bibliometric methods.

Methods

We retrieved TBS-related publications from January 1, 2004, to December 31, 2023, from the Web of Science Core Collection (WoSCC). The analysis focused on articles and review articles. Data were processed using the bibliometric package in R software, and CiteSpace and VOSviewer were employed for bibliometric and knowledge mapping analyses.

Results

A total of 1,206 publications were identified, with 858 included in the analysis. The annual publication volume showed a fluctuating upward trend. Leading institutions and authors were predominantly from the United States of America (USA) and European countries. Core journals and publications also primarily originated from these regions. Current research hotspots include the clinical applications and mechanisms of TBS in neurorehabilitation and depression. TBS cerebellar stimulation has emerged as a promising therapeutic target. Future research is likely to focus on dysphagia, cognitive impairments, and post-traumatic stress disorder.

Conclusion

This bibliometric analysis provides an overview of the basic knowledge structure, research hotspots, and development trends in TBS research over the past two decades. The findings offer valuable insights into the evolving landscape of TBS research and its potential directions.