Biophysical effects and neuromodulatory dose of transcranial ultrasonic stimulation

TL;DR

This paper reviews the biophysical mechanisms of transcranial ultrasonic stimulation (TUS), discusses safety and efficacy factors, and proposes a framework for TUS dose optimization based on biophysical effects and radiotherapy concepts.

Contribution

It introduces a comprehensive framework for understanding TUS dose by linking biophysical effects with safety and efficacy considerations.

Findings

Thermal and mechanical effects underpin TUS biological impact.

TUS parameters critically influence safety and effectiveness.

A new dose conceptualization framework for TUS is proposed.

Abstract

Transcranial ultrasonic stimulation (TUS) has the potential to usher in a new era for human neuroscience by allowing spatially precise and high-resolution non-invasive targeting of both deep and superficial brain regions. Currently, fundamental research on the mechanisms of interaction between ultrasound and neural tissues is progressing in parallel with application-focused research. However, a major hurdle in the wider use of TUS is the selection of optimal parameters to enable safe and effective neuromodulation in humans. In this paper, we will discuss the major factors that determine both the safety and efficacy of TUS. We will discuss the thermal and mechanical biophysical effects of ultrasound, which underlie its biological effects, in the context of their relationships with tunable parameters. Based on this knowledge of biophysical effects, and drawing on concepts from radiotherapy, we propose a framework for conceptualising TUS dose.