TUS – foundations

TUS has two types of biophysical effects on tissues: mechanical and thermal. This lecture discusses these effects in the context of existing safety guidelines for biomedical ultrasound applications (mainly diagnostic ultrasound), and introduces the risk aversive approach for assessing safety of novel TUS applications. The goal of this lecture is to provide the theoretical knowledge required for assessing TUS biophysical safety, including a discussion of useful methods and metrics.

At the end of this lecture, students will be able to choose appropriate metrics to assess the biophysical safety of a TUS application, taking into account both the stimulation parameters and characteristics of the human participants.

This lecture delves deeper into TUS protocols and effects. Specifically, it discuss the various parameters that encompass a protocol, and explains how the choice of parameters can influence the biophysical and ultimately neurophysiological effects of TUS. The goal of the lecture is to introduce students to the vast parameter space for TUS, and illustrate the effects of some common protocols that have been used so far.

At the end of this lecture, students will be able to describe the parameters that encompass a TUS protocol, and appreciate the complexity of the interactions between protocols and the brain itself, which ultimately determine the effects of TUS.

This lecture focuses on common confounds in TUS research, and uses examples from the literature to demonstrate how the effects of such confounds could be misinterpreted as neuromodulatory effects. The goal of the lecture is to make students aware of common confounds, and introduce them to the experimental methods that can be used to counteract or control for such confounds.

At the end of this lecture, students will be able to appreciate how challenging it can be to disentangle the effects of confounds from true neuromodulatory effects, and plan appropriate experimental controls for their own studies.

Learning from experiences with inter-individual variability in outcomes in TMS and tES, personalized and precision stimulation has has been prioritized from the early stages of TUS research. The goal of this lecture is to outline the motivations for, practice of, and recent advances in TUS simulations, with a particular focus on the effects of skull morphology.

At the end of this lecture, students will be able to articulate the value of simulations for guiding decisions about when, where and how to stimulate using TUS.

In order to ensure that ultrasound is transmitted from the transducer to the head with minimal attenuation, it is important to couple the transducer to the head using aqueous gel or other appropriate materials. The goal of this lecture is to introduce students to the physics of ultrasound wave propagation, with the aim of illustrating why coupling is crucial for TUS.

At the end of this lecture, students will be able to explain how reflection, refraction, scattering and absorption of ultrasound waves impacts transcranial ultrasound applications, and how attenuation can be mitigated by appropriate coupling.

This lecture delves deeper into the safety considerations for TUS. Data and experiences from the fields of deep brain stimulation and non-invasive electromagnetic stimulation are leveraged, in addition to animal and human TUS data. The goal of this lecture is to introduce students to a principled prospective assessment of risk and safety, given our knowledge of the physiological range of TUS effects.

At the end of this lecture, students will be able to assess the physiological risk and safety of a TUS experiment, given the current state of knowledge in the field.

This lecture is a practical demonstration of transcranial ultrasonic stimulation and neuronavigation in humans. The goal of this lecture is to provide hands-on experience in conducting safe and valid basic TUS experiments through use of neuronavigation. At the end of this practical demo, students will be able to implement the steps required for delivering TUS in humans. Specifically, the student will be able to register the participant to their MRI scan using neuronavigation, as well as perform the process required for adequate coupling and delivering of TUS.