Focused ultrasound neuromodulation

Modeling ultrasound modulation of neural function in a single cell

Background

Low intensity ultrasound stimulation has been shown to non-invasively modulate neural function in the central nervous system (CNS) and peripheral nervous system (PNS) with high precision. Ultrasound sonication is capable of either excitation or inhibition, depending on the ultrasound parameters used. On the other hand, the mode of interaction of ultrasonic waves with the neural tissue for effective neuromodulation remains ambiguous.

New method

Here within we propose a numerical model that incorporates the mechanical effects of ultrasound stimulation on the Hodgkin-Huxley (HH) neuron by incorporating the relation between increased external pressure and the membrane induced tension, with a stress on the flexoelectric effect on the neural membrane. The external pressure causes an increase in the total tension of the membrane thus affecting the probability of the ion channels being open after the conformational changes that those channels undergo.

Results

The interplay between varying the acoustic intensities and frequencies depicts different action potential suppression rates, whereby a combination of low intensity and low frequency ultrasound sonication proved to be the most effective in modulating neural function.Comparison with Existing Methods: Our method solely depends on the HH model of a single neuron and the linear flexoelectric effect of the dielectric neural membrane, when under an ultrasound-induced mechanical strain, while varying the ion-channels conductances based on different sonication frequencies and intensities. We study the effect of ultrasound parameters on the firing rate, latency, and action potential amplitude of a HH neuron for a better understanding of the neuromodulation modality of ultrasound stimulation (in the continuous and pulsed modes).

Conclusions

This simulation work confirms the published experimental data that low intensity and low frequency ultrasound sonication has a higher success rate of modulating neural firing.

Development and optimisation of in vitro sonodynamic therapy for glioblastoma

Sonodynamic therapy (SDT) is currently on critical path for glioblastoma therapeutics. SDT is a non-invasive approach utilising focused ultrasound to activate photosensitisers like 5-ALA to impede tumour growth. Unfortunately, the molecular mechanisms underlying the therapeutic functions of SDT remain enigmatic. This is primarily due to the lack of intricately optimised instrumentation capable of modulating SDT delivery to glioma cells in vitro. Consequently, very little information is available on the effects of SDT on glioma stem cells which are key drivers of gliomagenesis and recurrence. To address this, the current study has developed and validated an automated in vitro SDT system to allow the application and mapping of focused ultrasound fields under varied exposure conditions and setup configurations. The study optimizes ultrasound frequency, intensity, plate base material, thermal effect, and the integration of live cells. Indeed, in the presence of 5-ALA, focused ultrasound induces apoptotic cell death in primary patient-derived glioma cells with concurrent upregulation of intracellular reactive oxygen species. Intriguingly, primary glioma stem neurospheres also exhibit remarkably reduced 3D growth upon SDT exposure. Taken together, the study reports an in vitro system for SDT applications on tissue culture-based disease models to potentially benchmark the novel approach to the current standard-of-care.

Identifying commonalities in definition and governance of point-of-care ultrasound within statements from medical organizations in the United States: A scoping review for a shared understanding

This scoping review analyzed statements from 22 medical organizations in the United States to identify commonalities in the definition and governance of point-of-care ultrasound (POCUS). A total of 41 statements were included. The review found that the most commonly used elements in defining POCUS were "focused," "bedside," and "patient care." In terms of governance, consistent requirements included specific training programs, documentation in medical records, continuous quality assurance, and standards for credentialing and privileging. These findings suggest the existence of essential commonalities that could facilitate communication and the development of standardized POCUS programs in the future.

Anesthetic-loaded nanodroplets with focused ultrasound reduces agitation in Alzheimer's mice

OBJECTIVE

Alzheimer's disease (AD) is often associated with neuropsychiatric symptoms, including agitation and aggressive behavior. These symptoms increase with disease severity, ranging from 10% in mild cognitive impairment to 50% in patients with moderate-to-severe AD, pose a great risk for self-injury and injury to caregivers, result in high rates of institutionalization and great suffering for patients and families. Current pharmacological therapies have limited efficacy and a high potential for severe side effects. Thus, there is a growing need to develop novel therapeutics tailored to safely and effectively reduce agitation and aggressive behavior in AD. Here, we investigate for the first time the use of focused ultrasound combined with anesthetic-loaded nanodroplets (nanoFUS) targeting the amygdala (key structure in the neurocircuitry of agitation) as a novel minimally invasive tool to modulate local neural activity and reduce agitation and aggressive behavior in the TgCRND8 AD transgenic mice.

METHODS

Male and female animals were tested in the resident-intruder (i.e., aggressive behavior) and open-field tests (i.e., motor agitation) for baseline measures, followed by treatment with active- or sham-nanoFUS. Behavioral testing was then repeated after treatment.

RESULTS

Active-nanoFUS neuromodulation reduced aggressive behavior and agitation in male mice, as compared to sham-treated controls. Treatment with active-nanoFUS increased the time male mice spent in social-non-aggressive behaviors.

INTERPRETATION

Our results show that neuromodulation with active-nanoFUS may be a potential therapeutic tool for the treatment of neuropsychiatric symptoms, with special focus on agitation and aggressive behaviors. Further studies are necessary to establish cellular, molecular and long-term behavioral changes following treatment with nanoFUS.

Focused Ultrasound and Ultrasound Stimulated Microbubbles in Radiotherapy Enhancement for Cancer Treatment

Radiation therapy (RT) has been the standard of care for treating a multitude of cancer types. However, ionizing radiation has adverse short and long-term side effects which have resulted in treatment complications for decades. Thus, advances in enhancing the effects of RT have been the primary focus of research in radiation oncology. To avoid the usage of high radiation doses, treatment modalities such as high-intensity focused ultrasound can be implemented to reduce the radiation doses required to destroy cancer cells. In the past few years, the use of focused ultrasound (FUS) has demonstrated immense success in a number of applications as it capitalizes on spatial specificity. It allows ultrasound energy to be delivered to a targeted focal area without harming the surrounding tissue. FUS combined with RT has specifically demonstrated experimental evidence in its application resulting in enhanced cell death and tumor cure. Ultrasound-stimulated microbubbles have recently proved to be a novel way of enhancing RT as a radioenhancing agent on its own, or as a delivery vector for radiosensitizing agents such as oxygen. In this mini-review article, we discuss the bio-effects of FUS and RT in various preclinical models and highlight the applicability of this combined therapy in clinical settings.

Translational Approaches to Influence Sleep and Arousal

Sleep disorders are widespread in society and are prevalent in military personnel and in Veterans. Disturbances of sleep and arousal mechanisms are common in neuropsychiatric disorders such as schizophrenia, post-traumatic stress disorder, anxiety and affective disorders, traumatic brain injury, dementia, and substance use disorders. Sleep disturbances exacerbate suicidal ideation, a major concern for Veterans and in the general population. These disturbances impair quality of life, affect interpersonal relationships, reduce work productivity, exacerbate clinical features of other disorders, and impair recovery. Thus, approaches to improve sleep and modulate arousal are needed. Basic science research on the brain circuitry controlling sleep and arousal led to the recent approval of new drugs targeting the orexin/hypocretin and histamine systems, complementing existing drugs which affect GABA_A receptors and monoaminergic systems. Non-invasive brain stimulation techniques to modulate sleep and arousal are safe and show potential but require further development to be widely applicable. Invasive viral vector and deep brain stimulation approaches are also in their infancy but may be used to modulate sleep and arousal in severe neurological and psychiatric conditions. Behavioral, pharmacological, non-invasive brain stimulation and cell-specific invasive approaches covered here suggest the potential to selectively influence arousal, sleep initiation, sleep maintenance or sleep-stage specific phenomena such as sleep spindles or slow wave activity. These manipulations can positively impact the treatment of a wide range of neurological and psychiatric disorders by promoting the restorative effects of sleep on memory consolidation, clearance of toxic metabolites, metabolism, and immune function and by decreasing hyperarousal.