Transcranial magneto-acoustic stimulation enhances motor function and modulates cortical excitability of motor cortex in a Parkinson's disease mouse model

Parkinson's disease (PD) is a neurodegenerative disorder characterized primarily by motor dysfunction. Transcranial magneto-acoustic stimulation (TMAS), an emerging non-invasive brain neuromodulation technology, is increasingly being applied in the treatment of brain diseases. However, the effects of TMAS on PD are unknown, which is not well studied. Here, we utilized TMAS on PD model mice induced by MPTP to investigate the underlying mechanism of therapy. Our study found that TMAS improved the behavioral performance of PD model mice, enhancing the motor function and motivation for movement. Besides, it inhibited the increased beta oscillations in the motor cortex, while also reducing gamma oscillations. Moreover, the abnormally exaggerated beta-broad gamma phase amplitude coupling (PAC) was decreased after TMAS, and there was a significant negative correlation between PAC and both distance traveled and mean speed during the open filed test. Additionally, the ongoing stimulation could provide neuroprotection, implying that TMAS could ameliorate the loss of dopaminergic neurons, with no damage observed in the brain tissue of mice. Our findings suggest that TMAS could provide a non-invasive tool for the treatment of Parkinson's disease and beta-broad gamma phase amplitude coupling could be employed as a biomarker for PD.

A New Multi-Mode, High Pressure Portable Transcranial Ultrasound Stimulation System

OBJECTIVE

Transcranial ultrasound stimulation (TUS) is a promising non-invasive neuromodulation method for brain disorders. Commonly-used TUS systems in research include custom-built and commercial devices. Custom-built devices typically consist of traditional function generator, power amplifier, and ultrasound transducer. Due to cumbersome wiring and absence of dedicated control software, the operation of these devices is inconvenient. Commercial devices often have limited waveform modes and cannot perform ultrasound modulation with complex waveforms. These limitations limit the application of TUS technology by ordinary users. Therefore, we propose a portable TUS system with multiple modes and high acoustic pressure.

METHODS

The proposed portable TUS system utilizes a high-power multi-mode stimulator, and an ultrasound transducer with impedance matching module to achieve multiple modes and high acoustic pressure ultrasound neuromodulation.

RESULTS

The stimulator can output four types of waveforms: continuous pulse continuous stimulus (CPCS), intermittent pulse continuous stimulus (IPCS), continuous pulse intermittent stimulus (CPIS), and intermittent pulse intermittent stimulus (IPIS). When using a same transducer, it generates a peak negative pressure that is nearly identical to one produced by a commercial device. And compared to commercial transducer, the peak negative pressure of our transducer is significantly higher, reaching a maximum of 0.95 MPa.

CONCLUSION

In-vitro experiments were conducted using rat hippocampal brain slices. The experimental results demonstrated the effectiveness of the TUS system for neural stimulation.

SIGNIFICANCE

It offers a design method of a portable multi-mode, high pressure TUS system, which is used for complex neural modulation research.

Transcranial Focused Ultrasound Modifies Disease Progression in SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressively worsening neurodegenerative condition with very few treatment options available. Ultrasound neuromodulation offers promising benefits for treating neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. However, the effects and underlying mechanisms of ultrasound neuromodulation on ALS remain unclear. A head-mounted ultrasound neuromodulation system was developed to noninvasively stimulate the motor cortex of symptomatic mice carrying the G93A human SOD1 mutation (SOD $1^{\text {G93A}}$ ) for four weeks. Motor performance was assessed through the rotarod locomotor test, grip strength test, and open field test. In addition, the effect of ultrasound stimulation on the elastic modulus of gastrocnemius muscle atrophy was measured using real-time shear wave elastography (SWE). Subsequently, the brain tissues of the mice were harvested. Gastrocnemius morphology was examined using hematoxylin-eosin and Gomori aldehyde-fuchsin (GAF) staining. The number of neurons and the phenotype of microglia in the motor cortex were observed by immunohistochemical analysis. Ultrasound therapy delayed disease onset by 10.7% and increased the lifespan by 6.7% in SOD $1^{\text {G93A}}$ mice by reduction of neuronal loss and enhancement of M2 microglia in the motor cortex. Furthermore, we found significant improvements in motor function for ultrasound-treated mice. More importantly, ultrasound stimulation ameliorated gastrocnemius muscle atrophy in the SOD $1^{\text {G93A}}$ mice. These results revealed the neuroprotective effects of ultrasound against the disease pathogenesis of SOD $1^{\text {G93A}}$ mice. Transcranial ultrasound neuromodulation provides an innovative tool for the intervention and treatment of neurodegenerative diseases.

The effect of combined ultrasound stimulation and gastrodin on seizures in mice

Both physiotherapy and medicine play essential roles in the treatment of epilepsy. The purpose of this research was to evaluate the efficacy of the combined therapy with focus ultrasound stimulation (FUS) and gastrodin (GTD) on seizures in a mouse model. Kainic acid-induced seizure mice were divided into five groups randomly: sham, FUS, saline + sham, GTD + sham and GTD + FUS. The results showed that combined therapy with ultrasound stimulation and gastrodin can significantly reduce the number and duration of seizures in GTD + FUS group. 9.4T magnetic resonance imaging and histologic staining results revealed the underlying mechanism of the combined therapy may be that ultrasound stimulation increases cell membrane permeability to increase GTD concentration in brain. In addition, we verified the safety of FUS combined with GTD therapy. This research provides a new strategy for neurological disorders combining treatment of physical neuromodulation and medicine.

Holographic Ultrasound Modulates Neural Activity in a 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Mouse Model of Parkinson's Disease

Ultrasound (US) has emerged as a noninvasive neurostimulation method for motor control in Parkinson's disease (PD). Previous in vivo US neuromodulation studies for PD were single-target stimulation. However, the motor symptoms of PD are linked with neural circuit dysfunction, and multi-target stimulation is conducted in clinical treatment for PD. Thus, in the present study, we achieved multi-target US stimulation using holographic lens transducer based on the Rayleigh-Sommerfeld diffraction integral and time-reversal methods. We demonstrated that holographic US stimulation of the bilateral dorsal striatum (DS) could improve the motor function in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. The holographic US wave (fundamental frequency: 3 MHz, pulse repetition frequency: 500 Hz, duty cycle: 20%, tone-burst duration: 0.4 ms, sonication duration: 1 s, interstimulus interval: 4 s, spatial-peak temporal-average intensity: 180 mw/cm2) was delivered to the bilateral DS 20 min per day for consecutive 10 d after the last injection of MPTP. Immunohistochemical c-Fos staining demonstrated that holographic US significantly increased the c-Fos-positive neurons in the bilateral DS compared with the sham group (P = 0.003). Moreover, our results suggested that holographic US stimulation of the bilateral DS ameliorated motor dysfunction (P < 0.05) and protected the dopaminergic (DA) neurons (P < 0.001). The neuroprotective effect of holographic US was associated with the prevention of axon degeneration and the reinforcement of postsynaptic densities [growth associated protein-43 (P < 0.001), phosphorylated Akt (P = 0.001), β3-tubulin (P < 0.001), phosphorylated CRMP2 (P = 0.037), postsynaptic density (P = 0.023)]. These data suggested that holographic US-induced acoustic radiation force has the potential to achieve multi-target neuromodulation and could serve as a reliable tool for the treatment of PD.

Therapeutic ultrasound: an innovative approach for targeting neurological disorders affecting the basal ganglia

The basal ganglia are involved in motor control and action selection, and their impairment manifests in movement disorders such as Parkinson's disease (PD) and dystonia, among others. The complex neuronal circuitry of the basal ganglia is located deep inside the brain and presents significant treatment challenges. Conventional treatment strategies, such as invasive surgeries and medications, may have limited effectiveness and may result in considerable side effects. Non-invasive ultrasound (US) treatment approaches are becoming increasingly recognized for their therapeutic potential for reversibly permeabilizing the blood-brain barrier (BBB), targeting therapeutic delivery deep into the brain, and neuromodulation. Studies conducted on animals and early clinical trials using ultrasound as a therapeutic modality have demonstrated promising outcomes for controlling symptom severity while preserving neural tissue. These results could improve the quality of life for patients living with basal ganglia impairments. This review article explores the therapeutic frontiers of ultrasound technology, describing the brain mechanisms that are triggered and engaged by ultrasound. We demonstrate that this cutting-edge method could transform the way neurological disorders associated with the basal ganglia are managed, opening the door to less invasive and more effective treatments.

The combined use of thymoquinone and metformin provides more effective neuroprotection in a mouse model of MPTP-induced Parkinson's disease

Thymoquinone (TQ) is known for its antioxidant properties, and although metformin (MM) is known as an antidiabetic drug, it is suggested that it reduces neurodegeneration. The study aimed to investigate the neuroprotective effects of TQ and MM, particularly when used together, in relation to Parkinson's disease (PD). In the study, sixty-eight male C57BL/6 mice weighing 25-30 g were divided into five groups as follows: control, MPTP, MPTP+TQ, MPTP+MM, and MPTP+TQ+MM. MM (500 mg/kg, orally) and TQ (5 mg/kg, i.p.) were administered for 21 days. Motor coordination and locomotor activities were evaluated by the pole test. TOS and TAS analyses were conducted to determine oxidative stress levels in the substantia nigra. Dopaminergic degeneration in the substantia nigra was evaluated by analyzing Tyrosine hydroxylase (TH). To evaluate the apoptotic pathway, the expression levels of iNOS, BDNF, Complex 1, Bax, Bcl-2, Cytochrome C, AIF, and Caspase-3 were examined immunohistochemically. Compared to the MPTP-treated group, TQ, MM and MM+TQ treatment provided significant improvement in locomotor activity in mice, significantly increased antioxidant activity, significantly reduced the expression levels of iNOS, Bax, Cytochrome C, Caspase-3, and AIF, significantly increased BDNF, Bcl-2, and Complex 1 expressions, and significantly increased the number of TH positive cells. The separate use of TQ and MM exhibits neuroprotective activity, however, we showed that using TQ and MM in combination may be more effective. This may provide preclinical evidence supporting the therapeutic potential of their combined use for treating PD.

Low-intensity pulsed ultrasound modulates disease progression in the SOD1G93A mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the progressive loss of motor neurons in the brain and spinal cord, and there are no effective drug treatments. Low-intensity pulsed ultrasound (LIPUS) has garnered attention as a promising noninvasive neuromodulation method. In this study, we investigate its effects on the motor cortex and underlying mechanisms using the SOD1G93A mouse model of ALS. Our results show that LIPUS treatment delays disease onset and prolongs lifespan in ALS mice. LIPUS significantly increases cerebral blood flow in the motor cortex by preserving vascular endothelial cell integrity and increasing microvascular density, which may be mediated via the ion channel TRPV4. RNA sequencing analysis reveals that LIPUS substantially reduces the expression of genes associated with neuroinflammation. These findings suggest that LIPUS applied to the motor cortex may represent a potentially effective therapeutic tool for the treatment of ALS.

A Unique Time-Reversal Algorithm-Enabled Flexible Ultrasound Transducer with a Controllable Acoustic Field

Flexible ultrasonic devices represent a feasible technology for providing timely signal detection and even a non-invasive disease treatment for the human brain. However, the deformation of the devices is always accompanied by a change in the acoustic field, making it hard for accurate focusing. Herein, we report a stable and flexible transducer. This device can generate a high-intensity acoustic signal with a controllable acoustic field even when the device is bent. The key is to use a low-impedance piezoelectric material and an island-bridge device structure, as well as to design a unique time-reversal algorithm to correct the deviation of signals after transcranial propagation. To provide an in-depth study of the acoustic field of flexible devices, we also analyze the effects of mechanical deformation and structural parameters on the corresponding acoustic response.

Ultrasound Tissue Engineering Technology for Regulating Immune Microenvironment

The immune microenvironment is critical for the occurrence, progression, and treatment of diseases. Ultrasound tissue engineering technology utilizes ultrasound and the principles of tissue engineering to repair, regenerate, and functionally reconstruct biological tissues. Ultrasound therapy is a non‐invasive treatment modality that regulates the immune microenvironment and maintains homeostasis through various characteristic effects. Ultrasound‐responsive biomaterials utilize biological properties or drug/gene delivery to regulate the immune microenvironment under ultrasound stimulation for targeted and purposeful treatment. This article comprehensively and systematically reviews advancements in ultrasound tissue engineering technology for regulating the immune microenvironment. First, the changes in the immune microenvironment at different stages of the disease is briefly illustrated. It is then reviewed the regulation of the immune microenvironment by ultrasound and ultrasound‐responsive biomaterials in five types of diseases: tumor, cardiovascular system diseases, nervous system diseases, musculoskeletal diseases, and wound. Finally, the prospects of the ultrasound tissue engineering technology for regulating the immune microenvironment is summarized.

Wearable ultrasound devices: An emerging era for biomedicine and clinical translation

In recent years, personalized diagnosis and treatment have gained significant recognition and rapid development in the biomedicine and healthcare. Due to the flexibility, portability and excellent compatibility, wearable ultrasound (WUS) devices have become emerging personalized medical devices with great potential for development. Currently, with the development of the ongoing advancements in materials and structural design of the ultrasound transducers, WUS devices have improved performance and are increasingly applied in the medical field. In this review, we provide an overview of the design and structure of WUS devices, focusing on their application for diagnosis and treatment of various diseases from a clinical application perspective, and then explore the issues that need to be addressed before clinical translation. Finally, we summarize the progress made in the development of WUS devices, and discuss the current challenges and the future direction of their development. In conclusion, WUS devices usher an emerging era for biomedicine with great clinical promise.

Current state of clinical ultrasound neuromodulation

Unmatched by other non-invasive brain stimulation techniques, transcranial ultrasound (TUS) offers highly focal stimulation not only on the cortical surface but also in deep brain structures. These unique attributes are invaluable in both basic and clinical research and might open new avenues for treating neurological and psychiatric diseases. Here, we provide a concise overview of the expanding volume of clinical investigations in recent years and upcoming research initiatives concerning focused ultrasound neuromodulation. Currently, clinical TUS research addresses a variety of neuropsychiatric conditions, such as pain, dementia, movement disorders, psychiatric conditions, epilepsy, disorders of consciousness, and developmental disorders. As demonstrated in sham-controlled randomized studies, TUS neuromodulation improved cognitive functions and mood, and alleviated symptoms in schizophrenia and autism. Further, preliminary uncontrolled evidence suggests relieved anxiety, enhanced motor functions in movement disorders, reduced epileptic seizure frequency, improved responsiveness in patients with minimally conscious state, as well as pain reduction after neuromodulatory TUS. While constrained by the relatively modest number of investigations, primarily consisting of uncontrolled feasibility trials with small sample sizes, TUS holds encouraging prospects for treating neuropsychiatric disorders. Larger sham-controlled randomized trials, alongside further basic research into the mechanisms of action and optimal sonication parameters, are inevitably needed to unfold the full potential of TUS neuromodulation.

Neuromodulatory Responses Elicited by Intermittent versus Continuous Transcranial Focused Ultrasound Stimulation of the Motor Cortex in Rats

Transcranial focused ultrasound stimulation (tFUS) has emerged as a promising neuromodulation technique that delivers acoustic energy with high spatial resolution for inducing long-term potentiation (LTP)- or depression (LTD)-like plasticity. The variability in the primary effects of tFUS-induced plasticity could be due to different stimulation patterns, such as intermittent versus continuous, and is an aspect that requires further detailed exploration. In this study, we developed a platform to evaluate the neuromodulatory effects of intermittent and continuous tFUS on motor cortical plasticity before and after tFUS application. Three groups of rats were exposed to either intermittent, continuous, or sham tFUS. We analyzed the neuromodulatory effects on motor cortical excitability by examining changes in motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). We also investigated the effects of different stimulation patterns on excitatory and inhibitory neural biomarkers, examining c-Fos and glutamic acid decarboxylase (GAD-65) expression using immunohistochemistry staining. Additionally, we evaluated the safety of tFUS by analyzing glial fibrillary acidic protein (GFAP) expression. The current results indicated that intermittent tFUS produced a facilitation effect on motor excitability, while continuous tFUS significantly inhibited motor excitability. Furthermore, neither tFUS approach caused injury to the stimulation sites in rats. Immunohistochemistry staining revealed increased c-Fos and decreased GAD-65 expression following intermittent tFUS. Conversely, continuous tFUS downregulated c-Fos and upregulated GAD-65 expression. In conclusion, our findings demonstrate that both intermittent and continuous tFUS effectively modulate cortical excitability. The neuromodulatory effects may result from the activation or deactivation of cortical neurons following tFUS intervention. These effects are considered safe and well-tolerated, highlighting the potential for using different patterns of tFUS in future clinical neuromodulatory applications.

Spatiotemporal Distributions of Acoustic Propagation in Skull During Ultrasound Neuromodulation

There is widespread interest and concern about the evidence and hypothesis that the auditory system is involved in ultrasound neuromodulation. We have addressed this problem by performing acoustic shear wave simulations in mouse skull and behavioral experiments in deaf mice. The simulation results showed that shear waves propagating along the skull did not reach sufficient acoustic pressure in the auditory cortex to modulate neurons. Behavioral experiments were subsequently performed to awaken anesthetized mice with ultrasound targeting the motor cortex or ventral tegmental area (VTA). The experimental results showed that ultrasound stimulation (US) of the target areas significantly increased arousal scores even in deaf mice, whereas the loss of ultrasound gel abolished the effect. Immunofluorescence staining also showed that ultrasound can modulate neurons in the target area, whereas neurons in the auditory cortex required the involvement of the normal auditory system for activation. In summary, the shear waves propagating along the skull cannot reach the auditory cortex and induce neuronal activation. Ultrasound neuromodulation-induced arousal behavior needs direct action on functionally relevant stimulation targets in the absence of auditory system participation.

Efficacy of Wearable low-intensity pulsed Ultrasound treatment in the Movement disorder in Parkinson's disease (the SWUMP trial): protocol for a single-site, double-blind, randomized controlled trial

BACKGROUND

Parkinson's disease (PD) is a progressive, neurodegenerative illness marked by the loss of dopaminergic neurons, causing motor symptoms. Oral levodopa replacement therapy remains the gold standard in the treatment of PD. It is, nevertheless, a symptomatic treatment. There is currently no effective treatment for PD. Therefore, new therapies for PD are highly desirable. Low-intensity pulsed ultrasound (LIPUS) has been shown to improve behavioral functions in PD animal models. It is a new type of neuromodulation approach that combines noninvasiveness with high spatial precision. The purpose of this study is to establish a new clinical protocol for LIPUS in the treatment of movement disorders in patients with PD.

METHODS

This protocol is a single-site, prospective, double-blind, randomized controlled trial (RCT). Forty-eight participants with clinically confirmed PD will be randomly allocated to one of two groups: LIPUS group or sham group. All of the participants continue to use pharmacological therapy as a fundamental treatment. The primary outcome is the difference between groups from baseline to 4 months in the change in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score (part III). The secondary outcomes include the rating scales such as the Mini-Mental State Examination (MMSE), and other three rating scales, and medical examinations including high-density electroencephalography (hdEEG) and functional magnetic resonance imaging (fMRI). The primary safety outcome will be assessed at 4 months, and adverse events will be recorded.

DISCUSSION

This study represents the clinical investigation into the efficacy of therapeutic LIPUS in the treatment of PD for the first time. If LIPUS is determined to be effective, it could offer a practical and innovative means of expanding the accessibility of ultrasound therapy by using a wearable LIPUS device within a home setting.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100052093. Registered on 17 October 2021.

Transcranial Ultrasound Stimulation Improves Memory Performance of Parkinsonian Mice

Cognitive impairment is one of the most common non-motor symptoms of Parkinson's disease (PD). Previous studies have demonstrated that low-intensity transcranial ultrasound stimulation can significantly suppress the motor symptoms of PD. However, whether ultrasound stimulation can improve cognitive ability in PD and the related neural oscillation mechanism remain unclear to date. To evaluate the effect of ultrasound stimulation on memory ability in PD and explore its neural oscillation mechanism. Ultrasonography was used for 7-day stimulation of the CA1 in transgenic mice with PD. The working memory ability of the PD mice was then tested using novel object discrimination, and the local field potential and spikes in the mice CA1 were recorded at the same time as in the behavioral test. We found that ultrasound stimulation of the PD mice CA1 for 4 days: 1) significantly increased their learning and memory ability, although the learning and memory ability on the 7th day after the stimulation stopped was not significantly different from that before stimulation (P>0.05); 2) significantly increased the relative power of theta, low gamma, and high gamma frequency bands of the local field potential, and the phase amplitude coupling strength between theta and low gamma and between theta and high gamma; and 3) modulated the phase-locking angle between the spike of interneuron and theta wave to a 180°-360° rise cycle. Transcranial ultrasound stimulation can improve the learning and memory abilities of PD mice, and evoking neural oscillations in the CA1 is the potential mechanism.

A Self-Healing Optoacoustic Patch with High Damage Threshold and Conversion Efficiency for Biomedical Applications

Compared with traditional piezoelectric ultrasonic devices, optoacoustic devices have unique advantages such as a simple preparation process, anti-electromagnetic interference, and wireless long-distance power supply. However, current optoacoustic devices remain limited due to a low damage threshold and energy conversion efficiency, which seriously hinder their widespread applications. In this study, using a self-healing polydimethylsiloxane (PDMS, Fe-Hpdca-PDMS) and carbon nanotube composite, a flexible optoacoustic patch is developed, which possesses the self-healing capability at room temperature, and can even recover from damage induced by cutting or laser irradiation. Moreover, this patch can generate high-intensity ultrasound (> 25 MPa) without the focusing structure. The laser damage threshold is greater than 183.44 mJ cm-2, and the optoacoustic energy conversion efficiency reaches a major achievement at 10.66 × 10-3, compared with other carbon-based nanomaterials and PDMS composites. This patch is also been successfully examined in the application of acoustic flow, thrombolysis, and wireless energy harvesting. All findings in this study provides new insight into designing and fabricating of novel ultrasound devices for biomedical applications.

miR-214-3p promotes the pathogenesis of Parkinson's disease by inhibiting autophagy

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by dopaminergic neuron death in the substantia nigra, leading to motor dysfunction. Autophagy dysregulation has been implicated in PD pathogenesis. This study explores the role of miR-214-3p in PD, focusing on its impact on autophagy and dopaminergic neuron viability. Using in vitro and in vivo models, we demonstrate that miR-214-3p inhibits autophagy and promotes dopaminergic neuron apoptosis. Behavioral assessments and molecular analyses reveal exacerbation of PD symptoms upon miR-214-3p overexpression. Furthermore, mechanistic investigations identify ATG3 as a target, shedding light on miR-214-3p's regulatory role in autophagy. These findings enhance our understanding of PD pathogenesis and propose miR-214-3p as a potential biomarker and therapeutic target for modulating autophagy and neuronal survival in PD.

Ultrasound Deep Brain Stimulation Regulates Food Intake and Body Weight in Mice

Given the widespread occurrence of obesity, new strategies are urgently needed to prevent, halt and reverse this condition. We proposed a noninvasive neurostimulation tool, ultrasound deep brain stimulation (UDBS), which can specifically modulate the hypothalamus and effectively regulate food intake and body weight in mice. Fifteen-min UDBS of hypothalamus decreased 41.4% food intake within 2 hours. Prolonged 1-hour UDBS significantly decreased daily food intake lasting 4 days. UDBS also effectively restrained body weight gain in leptin-receptor knockout mice (Sham: 96.19%, UDBS: 58.61%). High-fat diet (HFD) mice treated with 4-week UDBS (15 min / 2 days) reduced 28.70% of the body weight compared to the Sham group. Meanwhile, UDBS significantly modulated glucose-lipid metabolism and decreased the body fat. The potential mechanism is that ultrasound actives pro-opiomelanocortin (POMC) neurons in the hypothalamus for reduction of food intake and body weight. These results provide a noninvasive tool for controlling food intake, enabling systematic treatment of obesity.

Neuropsychiatric Behavioral Assessments in Mice After Acute and Long-Term Treatments of Low-Intensity Pulsed Ultrasound

Introduction: To evaluate whether both acute and chronic low-intensity pulsed ultrasound (LIPUS) affect brain functions of healthy male and female mice. Methods: Ultrasound (frequency: 1.5 MHz; pulse: 1.0 kHz; spatial average temporal average (SATA) intensity: 25 mW/cm2; and pulse duty cycle: 20%) was applied at mouse head in acute test for 20 minutes, and in chronic experiment for consecutive 10 days, respectively. Behaviors were then evaluated. Results: Both acute and chronic LIPUS at 25 mW/cm2 exposure did not affect the abilities of movements, mating, social interaction, and anxiety-like behaviors in the male and female mice. However, physical restraint caused struggle-like behaviors and short-time memory deficits in chronic LIPUS groups in the male mice. Conclusion: LIPUS at 25 mW/cm2 itself does not affect brain functions, while physical restraint for LIPUS therapy elicits struggle-like behaviors in the male mice. An unbound helmet targeted with ultrasound intensity at 25-50 mW/cm2 is proposed for clinical brain disease therapy.

The effectiveness and safety of low-intensity transcranial ultrasound stimulation: A systematic review of human and animal studies

Low-intensity transcranial ultrasound stimulation (LITUS) is a novel non-invasive neuromodulation technique. We conducted a systematic review to evaluate current evidence on the efficacy and safety of LITUS neuromodulation. Five databases were searched from inception to May 31, 2023. Randomized controlled human trials and controlled animal studies were included. The neuromodulation effects of LITUS on clinical or pre-clinical, neurophysiological, neuroimaging, histological and biochemical outcomes, and adverse events were summarized. In total, 11 human studies and 44 animal studies were identified. LITUS demonstrated therapeutic efficacy in neurological disorders, psychiatric disorders, pain, sleep disorders and hypertension. LITUS-related changes in neuronal structure and cortical activity were found. From histological and biochemical perspectives, prominent findings included suppressing the inflammatory response and facilitating neurogenesis. No adverse effects were reported in controlled animal studies included in our review, while reversible headache, nausea, and vomiting were reported in a few human subjects. Overall, LITUS alleviates various symptoms and modulates associated brain circuits without major side effects. Future research needs to establish a solid therapeutic framework for LITUS.

Therapeutic Viewpoint on Rat Models of Locomotion Abnormalities and Neurobiological Indicators in Parkinson's Disease

BACKGROUND

Locomotion problems in Parkinson's syndrome are still a research and treatment difficulty. With the recent introduction of brain stimulation or neuromodulation equipment that is sufficient to monitor activity in the brain using electrodes placed on the scalp, new locomotion investigations in patients having the capacity to move freely have sprung up.

OBJECTIVE

This study aimed to find rat models and locomotion-connected neuronal indicators and use them all over a closed-loop system to enhance the future and present treatment options available for Parkinson's disease.

METHODS

Various publications on locomotor abnormalities, Parkinson's disease, animal models, and other topics have been searched using several search engines, such as Google Scholar, Web of Science, Research Gate, and PubMed.

RESULTS

Based on the literature, we can conclude that animal models are used for further investigating the locomotion connectivity deficiencies of many biological measuring devices and attempting to address unanswered concerns from clinical and non-clinical research. However, translational validity is required for rat models to contribute to the improvement of upcoming neurostimulation-based medicines. This review discusses the most successful methods for modelling Parkinson's locomotion in rats.

CONCLUSION

This review article has examined how scientific clinical experiments lead to localised central nervous system injuries in rats, as well as how the associated motor deficits and connection oscillations reflect this. This evolutionary process of therapeutic interventions may help to improve locomotion- based treatment and management of Parkinson's syndrome in the upcoming years.

Low-intensity pulsed ultrasound stimulation (LIPUS) modulates microglial activation following intracortical microelectrode implantation

Microglia are important players in surveillance and repair of the brain. Their activation mediates neuroinflammation caused by intracortical microelectrode implantation, which impedes the application of intracortical brain-computer interfaces (BCIs). While low-intensity pulsed ultrasound stimulation (LIPUS) can attenuate microglial activation, its potential to modulate the microglia-mediated neuroinflammation and enhance the bio-integration of microelectrodes remains insufficiently explored. We found that LIPUS increased microglia migration speed from 0.59±0.04 to 1.35±0.07 µm/hr on day 1 and enhanced microglia expansion area from 44.50±6.86 to 93.15±8.77 µm 2 /min on day 7, indicating improved tissue healing and surveillance. Furthermore, LIPUS reduced microglial activation by 17% on day 6, vessel-associated microglia ratio from 70.67±6.15 to 40.43±3.87% on day 7, and vessel diameter by 20% on day 28. Additionally, microglial coverage of the microelectrode was reduced by 50% in week 1, indicating better tissue-microelectrode integration. These data reveal that LIPUS helps resolve neuroinflammation around chronic intracortical microelectrodes.

Transcranial ultrasound neuromodulation facilitates isoflurane-induced general anesthesia recovery and improves cognition in mice

Delayed arousal and cognitive dysfunction are common, especially in older patients after general anesthesia (GA). Elevating central nervous system serotonin (5-HT) levels can promote recovery from GA and increase synaptic plasticity to improve cognition. Ultrasound neuromodulation has become a noninvasive physical intervention therapy with high spatial resolution and penetration depth, which can modulate neuronal excitability to treat psychiatric and neurodegenerative diseases. This study aims to use ultrasound to noninvasively modulate the brain 5-HT levels of mice to promote recovery from GA and improve cognition in mice. The dorsal raphe nucleus (DRN) of mice during GA was stimulated by the 1.1 MHz ultrasound with a negative pressure of 356 kPa, and the liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) method was used to measure the DRN 5-HT concentrations. The mice's recovery time from GA was assessed, and the cognition was evaluated through spontaneous alternation Y-maze and novel object recognition (NOR) tests. After ultrasound stimulation, the mice's DRN 5-HT levels were significantly increased (control: 554.0 ± 103.2 ng/g, anesthesia + US: 664.2 ± 84.1 ng/g, *p = 0.0389); the GA recovery time (return of the righting reflex (RORR) emergence latency time) of mice was significantly reduced (anesthesia: 331.6 ± 70 s, anesthesia + US: 223.2 ± 67.7 s, *p = 0.0215); the spontaneous rotation behavior score of mice was significantly increased (anesthesia: 59.46 ± 5.26 %, anesthesia + US: 68.55 ± 5.24 %; *p = 0.0126); the recognition index was significantly increased (anesthesia: 55.02 ± 6.23 %, anesthesia + US: 78.52 ± 12.21 %; ***p = 0.0009). This study indicates that ultrasound stimulation of DRN increases serotonin levels, accelerates recovery from anesthesia, and improves cognition, which could be an important strategy for treating delayed arousal, postoperative delirium, or even lasting cognitive dysfunction after GA.

A Review of Ultrasound Neuromodulation Technologies

The invasiveness of neuromodulation technologies that require surgical implantation (e.g., electrical and optical stimulation) may limit their clinical application. Thus, alternative technologies that offer similar benefits without surgery are of paramount importance in the field of neuromodulation. Low-intensity ultrasound is an emerging modality for neural stimulation as ultrasound can be focused in deep tissues with millimeter resolution. Transcranial focused ultrasound stimulation (tFUS) has already been demonstrated in a wide range of animals and even humans at different sonication frequencies (mostly in the sub-MHz range due to the presence of the skull). This article first provides some fundamental knowledge in ultrasound, and then reviews various examples of successful tFUS experiments in animals and humans using different stimulation patterns, as well as available tFUS technologies for generating, focusing, and steering ultrasound beams in neural tissues. In particular, phased array technologies for the ultrasound stimulation application are discussed with an emphasis on the design, fabrication, and integration of ultrasound transducer arrays as well as the design and development of phased array electronics with beamformer and high-voltage driver circuitry. The challenges in tFUS, such as its underlying mechanism, indirect auditory response, and skull aberration effects, are also discussed.

Soft Bioelectronics for Therapeutics

Soft bioelectronics play an increasingly crucial role in high-precision therapeutics due to their softness, biocompatibility, clinical accuracy, long-term stability, and patient-friendliness. In this review, we provide a comprehensive overview of the latest representative therapeutic applications of advanced soft bioelectronics, ranging from wearable therapeutics for skin wounds, diabetes, ophthalmic diseases, muscle disorders, and other diseases to implantable therapeutics against complex diseases, such as cardiac arrhythmias, cancer, neurological diseases, and others. We also highlight key challenges and opportunities for future clinical translation and commercialization of soft therapeutic bioelectronics toward personalized medicine.

Noninvasive Neuromodulation in Parkinson's Disease: Insights from Animal Models

The mainstay treatments for Parkinson's Disease (PD) have been limited to pharmacotherapy and deep brain stimulation. While these interventions are helpful, a new wave of research is investigating noninvasive neuromodulation methods as potential treatments. Some promising avenues have included transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), electroconvulsive therapy (ECT), and focused ultrasound (FUS). While these methods are being tested in PD patients, investigations in animal models of PD have sought to elucidate their therapeutic mechanisms. In this rapid review, we assess the available animal literature on these noninvasive techniques and discuss the possible mechanisms mediating their therapeutic effects based on these findings.

The Emergence of Functional Ultrasound for Noninvasive Brain-Computer Interface

A noninvasive brain-computer interface is a central task in the comprehensive analysis and understanding of the brain and is an important challenge in international brain-science research. Current implanted brain-computer interfaces are cranial and invasive, which considerably limits their applications. The development of new noninvasive reading and writing technologies will advance substantial innovations and breakthroughs in the field of brain-computer interfaces. Here, we review the theory and development of the ultrasound brain functional imaging and its applications. Furthermore, we introduce latest advancements in ultrasound brain modulation and its applications in rodents, primates, and human; its mechanism and closed-loop ultrasound neuromodulation based on electroencephalograph are also presented. Finally, high-frequency acoustic noninvasive brain-computer interface is prospected based on ultrasound super-resolution imaging and acoustic tweezers.

Ultrasound deep brain stimulation decelerates telomere shortening in Alzheimer's disease and aging mice

Telomere length is a reliable biomarker for health and longevity prediction in both humans and animals. The common neuromodulation techniques, including deep brain stimulation (DBS) and optogenetics, have excellent spatial resolution and depth penetration but require implementation of electrodes or optical fibers. Therefore, it is important to develop methods for noninvasive modulation of telomere length. Herein, we reported on a new method for decelerating telomere shortening using noninvasive ultrasound deep brain stimulation (UDBS). Firstly, we found that UDBS could activate the telomerase-associated proteins in normal mice. Then, in the Alzheimer's disease mice, UDBS was observed to decelerate telomere shortening of the cortex and myocardial tissue and to effectively improve spatial learning and memory abilities. Similarly, UDBS was found to significantly slow down telomere shortening of the cortex and peripheral blood, and improve motor and cognitive functions in aging mice. Finally, transcriptome analysis revealed that UDBS upregulated the neuroactive ligand-receptor interaction pathway. Overall, the present findings established the critical role of UDBS in delaying telomere shortening and indicated that ultrasound modulation of telomere length may constitute an effective therapeutic strategy for aging and aging-related diseases.

Simultaneous multi-target ultrasound neuromodulation in freely-moving mice based on a single-element ultrasound transducer

Objective.Ultrasound neuromodulation has become an emerging method for the therapy of neurodegenerative and psychiatric diseases. The phased array ultrasonic transducer enables multi-target ultrasound neuromodulation in small animals, but the relatively large size and mass and the thick cables of the array limit the free movement of small animals. Furthermore, spatial interference may occur during multi-target ultrasound brain stimulation with multiple micro transducers.Approach.In this study, we developed a miniature power ultrasound transducer and used the virtual source time inversion method and 3D printing technology to design, optimize, and manufacture the acoustic holographic lens to construct a multi-target ultrasound neuromodulation system for free-moving mice. The feasibility of the system was verified byin vitrotranscranial ultrasound field measurements,in vivodual-target blood-brain barrier (BBB) opening experiments, andin vivodual-target ultrasound neuromodulation experiments.Main results.The developed miniature transducer had a diameter of 4.0 mm, a center frequency of 1.1 MHz, and a weight of 1.25 g. The developed miniature acoustic holographic lens had a weight of 0.019 g to generate dual-focus transcranial ultrasound. The ultrasonic field measurements' results showed that the bifocal's horizontal distance was 3.0 mm, the -6 dB focal spot width in thex-direction was 2.5 and 2.25 mm, and 2.12 and 2.24 mm in they-direction. Finally, thein vivoexperimental results showed that the system could achieve dual-target BBB opening and ultrasound neuromodulation in freely-moving mice.Significance.The ultrasonic neuromodulation system based on a miniature single-element transducer and the miniature acoustic holographic lens could achieve dual-target neuromodulation in awake small animals, which is expected to be applied to the research of non-invasive dual-target ultrasonic treatment of brain diseases in awake small animals.

Low intensity focused ultrasound: a new prospect for the treatment of Parkinson's disease

Background: As a chronic and progressive neurodegenerative disease, Parkinson's disease (PD) still lacks effective and safe targeted drug therapy. Low-intensity focused ultrasound (LIFU), a new method to stimulate the brain and open the blood-brain barrier (BBB), has been widely concerned by PD researchers due to its non-invasive characteristics.Methods: PubMed was searched for the past 10 years using the terms 'focused ultrasound', 'transcranial ultrasound', 'pulse ultrasound', and 'Parkinson's disease'. Relevant citations were selected from the authors' references. After excluding articles describing high-intensity focused ultrasound or non-Parkinson's disease applications, we found more than 100 full-text analyses for pooled analysis.Results: Current preclinical studies have shown that LIFU could improve PD motor symptoms by regulating microglia activation, increasing neurotrophic factors, reducing oxidative stress, and promoting nerve repair and regeneration, while LIFU combined with microbubbles (MBs) can promote drugs to cross the BBB, which may become a new direction of PD treatment. Therefore, finding an efficient drug carrier system is the top priority of applying LIFU with MBs to deliver drugs.Conclusions: This article aims to review neuro-modulatory effect of LIFU and the possible biophysical mechanism in the treatment of PD, summarize the latest progress in delivering vehicles with MBs, and discuss its advantages and limitations.

General-Purpose Ultrasound Neuromodulation System for Chronic, Closed-Loop Preclinical Studies in Freely Behaving Rodents

Transcranial focused ultrasound stimulation (tFUS) is an effective noninvasive treatment modality for brain disorders with high clinical potential. However, the therapeutic effects of ultrasound neuromodulation are not widely explored due to limitations in preclinical systems. The current preclinical studies are head-fixed, anesthesia-dependent, and acute, limiting clinical translatability. Here, this work reports a general-purpose ultrasound neuromodulation system for chronic, closed-loop preclinical studies in freely behaving rodents. This work uses microelectromechanical systems (MEMS) technology to design and fabricate a small and lightweight transducer capable of artifact-free stimulation and simultaneous neural recording. Using the general-purpose system, it can be observed that state-dependent ultrasound neuromodulation of the prefrontal cortex increases rapid eye movement (REM) sleep and protects spatial working memory to REM sleep deprivation. The system will allow explorative studies in brain disease therapeutics and neuromodulation using ultrasound stimulation for widespread clinical adoption.

Ultrasound Deep Brain Stimulation Modulates Body Temperature in Mice

Body temperature plays a critical role in rehabilitation, and numerous studies proved that the regulation of body temperature contributes to the sensorimotor recovery of patients with brain diseases such as stroke. The hypothalamus plays a key role in thermoregulation. Ultrasound deep brain stimulation (UDBS) can noninvasively modulate deep brain nuclei and have potential applications in the treatment of Parkinson's disease, Alzheimer's disease, and depression, among others. The purpose of this study was to investigate whether ultrasound stimulation of the hypothalamus could regulate body temperature in free-moving mice. Results showed that thermoregulation was related to ultrasonic parameters (pulse repetition frequency (PRF), duty cycle, total time, and acoustic pressure). UDBS of the preoptic area of the anterior hypothalamus at 500 Hz PRF could significantly reduce body temperature ( [Formula: see text] at t = 5 min, [Formula: see text] at t = 10 min, [Formula: see text] at t = 15 min). Meanwhile, UDBS of the dorsomedial hypothalamus at 10 Hz PRF triggered a significant increase in body temperature ( [Formula: see text] at t = 5 min, [Formula: see text] at t = 10 min). These results suggest that UDBS, as a noninvasive neuromodulation tool, may play a key role in the future clinical treatment of malignant hyperthermia and hypothermia.

Low-Intensity Transcranial Ultrasound Stimulation: Mechanisms of Action and Rationale for Future Applications in Movement Disorders

Low-intensity transcranial ultrasound stimulation (TUS) is a novel non-invasive brain stimulation technique that uses acoustic energy to induce changes in neuronal activity. However, although low-intensity TUS is a promising neuromodulation tool, it has been poorly studied as compared to other methods, i.e., transcranial magnetic and electrical stimulation. In this article, we first focus on experimental studies in animals and humans aimed at explaining its mechanisms of action. We then highlight possible applications of TUS in movement disorders, particularly in patients with parkinsonism, dystonia, and tremor. Finally, we highlight the knowledge gaps and possible limitations that currently limit potential TUS applications in movement disorders. Clarifying the potential role of TUS in movement disorders may further promote studies with therapeutic perspectives in this field.

Transcranial Focused Ultrasound Stimulation of Periaqueductal Gray for Analgesia

OBJECTIVE

Transcranial focused ultrasound (tFUS) is regarded as a promising non-invasive stimulation tool for modulating brain circuits. The aim of this study is to explore the feasibility of tFUS stimulation for analgesia application.

METHODS

50 l of 3% formalin solution was injected into the rats left hindpaw to build a pain model, and then the local field potential (LFP) activities of the dorsal horn were tracked after a recording electrode was placed in the spinal cord. Rats were randomly divided into two groups: control group and tFUS group. At the 30th minute after formalin injection, tFUS (US-650 kHz, PD = 1 ms, PRF = 100 Hz, 691 mW/cm2) was conducted to stimulate the periaqueductal gray (PAG) for 5 minutes (on 5 s and off 5 s) in tFUS group, but there was no treatment in control group. In addition, the analgesia mechanism (LFP recording from the PAG) and safety assessment (histology analysis) were carried out.

RESULTS

The tFUS stimulation of the PAG can suppress effectively the nociceptive activity generated by formalin. The findings of the underlying mechanism exploration indicated that the tFUS stimulation was able to activate the PAG directly without causing significant temperature change and tissue injury.

CONCLUSION

The results illustrated that the tFUS stimulation of the PAG can achieve the effect of analgesia.

SIGNIFICANCE

This work provides new insights for the development of non-invasive analgesic technology in the future.

Dopaminergic modulation of primary motor cortex: From cellular and synaptic mechanisms underlying motor learning to cognitive symptoms in Parkinson's disease

The primary motor cortex (M1) is crucial for movement execution, especially dexterous ones, but also for cognitive functions like motor learning. The acquisition of motor skills to execute dexterous movements requires dopamine-dependent and -independent plasticity mechanisms within M1. In addition to the basal ganglia, M1 is disturbed in Parkinson's disease (PD). However, little is known about how the lack of dopamine (DA), characteristic of PD, directly or indirectly impacts M1 circuitry. Here we review data from studies of PD patients and the substantial research in non-human primate and rodent models of DA depletion. These models enable us to understand the importance of DA in M1 physiology at the behavioral, network, cellular, and synaptic levels. We first summarize M1 functions and neuronal populations in mammals. We then look at the origin of M1 DA and the cellular location of its receptors and explore the impact of DA loss on M1 physiology, motor, and executive functions. Finally, we discuss how PD treatments impact M1 functions.

A Spatial Multitarget Ultrasound Neuromodulation System Using High-Powered 2-D Array Transducer

Transcranial focused ultrasound (tFUS) is increasingly used in experimental neuroscience due to its neuromodulatory effectiveness in animal studies. However, achieving multitarget tFUS in small animals is typically limited by transducer size, energy transfer efficiency, and brain volume. The objective of this work was to construct an ultrasound system for multitarget neuromodulation in small animals. First, a miniaturized high-powered 2-D array transducer was developed. The phase delay of each array element was calculated based on the multifocal time-reversal method, generating multiple foci simultaneously in a 3-D field. The effects of the axial focal length, interfocus spacing (lateral distance between the two focal centers), and the number of foci on the focal properties of the pressure field were examined through numerical simulations. In-vitro ultrasonic measurements and transcranial simulations on a rat skull were conducted. The minimum interfocus spacing separating two -6-dB foci and the peak full-width at half-maximum were positively correlated with axial focal length; the relative relationship between the interfocus spacing and pressure field properties was similar for each axial focal length. The maximum acoustic pressure and spatial average intensity at focus in deionized water were 2.21 MPa and 133 W/cm², respectively. The simulated and experimental results were compared, demonstrating agreement in both peak position and focus shape. The ultrasound system can provide a neuroscientific platform for evaluating the feasibility of multitarget ultrasound stimulation treatment protocols, thus improving the understanding of functional neuroanatomy.

Focused Ultrasound Stimulation as a Neuromodulatory Tool for Parkinson's Disease: A Scoping Review

Non-invasive focused ultrasound stimulation (FUS) is a non-ionising neuromodulatory technique that employs acoustic energy to acutely and reversibly modulate brain activity of deep-brain structures. It is currently being investigated as a potential novel treatment for Parkinson's disease (PD). This scoping review was carried out to map available evidence pertaining to the provision of FUS as a PD neuromodulatory tool. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews, a search was applied to Ovid MEDLINE, Embase, Web of Science and Cochrane Central Register of Controlled Trials on 13 January 2022, with no limits applied. In total, 11 studies were included: 8 were from China and 1 each from Belgium, South Korea and Taiwan. All 11 studies were preclinical (6 in vivo, 2 in vitro, 2 mix of in vivo and in vitro and 1 in silico). The preclinical evidence indicates that FUS is safe and has beneficial neuromodulatory effects on motor behaviour in PD. FUS appears to have a therapeutic role in influencing the disease processes of PD, and therefore holds great promise as an attractive and powerful neuromodulatory tool for PD. Though these initial studies are encouraging, further study to understand the underlying cellular and molecular mechanisms is required before FUS can be routinely used in PD.

Anti-inflammatory and Neuroprotective Effects of Transcranial Ultrasound Stimulation on Parkinson's Disease

Low-intensity pulsed ultrasound (LIPUS) is a promising non-invasive neuromodulation tool for deep brain stimulation. Here, we investigated the impact of LIPUS, including neuroprotective effects, on the pathology of Parkinson's disease (PD) in an animal model. Sprague-Dawley rats were injected with 6-hydroxydopamine (6-OHDA) at two sites in the right striatum. LIPUS (1 MHz, 5% duty cycle, 1-Hz pulse repetition frequency, 15 min/d) stimulation was then applied to some of the rats (the 6-OHDA + LIPUS group) beginning 2 wk after the 6-OHDA administration, while the remaining rats (the 6-OHDA group) received no LIPUS stimulation. The 6-OHDA-induced inflammatory responses and expressions of neurotrophic factors were quantified with immunofluorescence activity. The safety of LIPUS was assessed using hematoxylin and eosin and Nissl staining. LIPUS treatment significantly inhibited 6-OHDA-induced glial activation and the phosphorylation of nuclear factor-κB p65 in the substantia nigra pars compacta. Further study revealed that LIPUS effectively preserved the levels of neurotrophic factors, dopamine transporter and tight junction proteins of the blood-brain barrier in the 6-OHDA + LIPUS group compared with the 6-OHDA group. These results indicate that LIPUS acts via multiple neuroprotective mechanisms in the PD rat model and suggest that LIPUS can be viewed as a potential treatment for PD.

Multitarget Transcranial Ultrasound Therapy in Small Animals Based on Phase-Only Acoustic Holographic Lens

Transcranial ultrasound therapy has become a noninvasive method for treating neurological and psychiatric disorders, and studies have further demonstrated that multitarget transcranial ultrasound therapy is a better solution. At present, multitarget transcranial ultrasound therapy in small animals can only be achieved by the multitransducer or phased array. However, multiple transducers may cause spatial interference, and the phased array system is complicated, expensive, and especially unsuitable for small animals. This study is the first to design and fabricate a miniature acoustic holography lens for multitarget transcranial ultrasound therapy in rats. The acoustic holographic lens, working at a frequency of 1.0 MHz, with a size of 10.08 mm ×10.08 mm and a pixel resolution of 0.72 mm, was designed, optimized, and fabricated. The dual-focus transcranial ultrasound generated based on the lens was measured; the full-width at half-maximum (FWHM) of the focal spots in the y -direction was 2.15 and 2.27 mm and in the z -direction was 2.3 and 2.36 mm. The focal length was 5.4 mm, and the distance between the two focuses was 5.6 mm, close to the desired values of 5.4 and 6.0 mm. Finally, the multiple-target blood-brain barrier opening in rats' bilateral secondary visual cortex (mediolateral area, V2ML) was demonstrated using the transcranial ultrasound therapy system based on the lens. These results demonstrate the good performance of the multitarget transcranial ultrasound therapy system for small animals, including high spatial resolution, small size, and low cost.

Transcranial Ultrasound Stimulation of the Anterior Cingulate Cortex Reduces Neuropathic Pain in Mice

Focused ultrasound (FUS) is a potential tool for treating chronic pain by modulating the central nervous system. Herein, we aimed to determine whether transcranial FUS stimulation of the anterior cingulate cortex (ACC) effectively improved chronic pain in the chronic compress injury mice model at different stages of neuropathic pain. The mechanical threshold of pain was recorded in the nociceptive tests. We found FUS stimulation elevated the mechanical threshold of pain in both short-term (p < 0.01) and long-term (p < 0.05) experiments. Furthermore, we determined protein expression differences in ACC between the control group, the intervention group, and the Sham group to analyze the underlying mechanism of FUS stimulation in improving neuropathic pain. Additionally, the results showed FUS stimulation led to alterations in differential proteins in long-term experiments, including cellular processes, cellular signaling, and information storage and processing. Our findings indicate FUS may effectively alleviate mechanical neuropathic pain via the ACC's stimulation, especially in the chronic state.

32 Element Piezoelectric Micromachined Ultrasound Transducer (PMUT) Phased Array for Neuromodulation

Interest in utilizing ultrasound (US) transducers for non-invasive neuromodulation treatment, including for low intensity transcranial focused ultrasound stimulation (tFUS), has grown rapidly. The most widely demonstrated US transducers for tFUS are either bulk piezoelectric transducers or capacitive micromachine transducers (CMUT) which require high voltage excitation to operate. In order to advance the development of the US transducers towards small, portable devices for safe tFUS at large scale, a low voltage array of US transducers with beam focusing and steering capability is of interest. This work presents the design methodology, fabrication, and characterization of 32-element phased array piezoelectric micromachined ultrasound transducers (PMUT) using 1.5 μm thick Pb(Zr_0.52 Ti_0.48)O₃ films doped with 2 mol% Nb. The electrode/piezoelectric/electrode stack was deposited on a silicon on insulator (SOI) wafer with a 2 μm silicon device layer that serves as the passive elastic layer for bending-mode vibration. The fabricated 32-element PMUT has a central frequency at 1.4 MHz. Ultrasound beam focusing and steering (through beamforming) was demonstrated where the array was driven with 14.6 V square unipolar pulses. The PMUT generated a maximum peak-to-peak focused acoustic pressure output of 0.44 MPa at a focal distance of 20 mm with a 9.2 mm and 1 mm axial and lateral resolution, respectively. The maximum pressure is equivalent to a spatial-peak pulse-average intensity of 1.29 W/cm², which is suitable for tFUS application.

Improved alpha-beta power reduction via combined electrical and ultrasonic stimulation in a parkinsonian cortex-basal ganglia-thalamus computational model

Objective. To investigate computationally the interaction of combined electrical and ultrasonic modulation of isolated neurons and of the parkinsonian cortex-basal ganglia-thalamus loop.Approach. Continuous-wave or pulsed electrical and ultrasonic neuromodulation is applied to isolated Otsuka plateau-potential generating subthalamic nucleus (STN) and Pospischil regular, fast and low-threshold spiking cortical cells in a temporally alternating or simultaneous manner. Similar combinations of electrical/ultrasonic waveforms are applied to a parkinsonian biophysical cortex-basal ganglia-thalamus neuronal network. Ultrasound-neuron interaction is modelled respectively for isolated neurons and the neuronal network with the NICE and SONIC implementations of the bilayer sonophore underlying mechanism. Reduction inα-βspectral energy is used as a proxy to express improvement in Parkinson's disease by insonication and electrostimulation.Main results. Simultaneous electro-acoustic stimulation achieves a given level of neuronal activity at lower intensities compared to the separate stimulation modalities. Conversely, temporally alternating stimulation with50 Hzelectrical and ultrasound pulses is capable of eliciting100 HzSTN firing rates. Furthermore, combination of ultrasound with hyperpolarizing currents can alter cortical cell relative spiking regimes. In the parkinsonian neuronal network, continuous-wave and pulsed ultrasound reduce pathological oscillations by different mechanisms. High-frequency pulsed separated electrical and ultrasonic deep brain stimulation (DBS) reduce pathologicalα-βpower by entraining STN-neurons. In contrast, continuous-wave ultrasound reduces pathological oscillations by silencing the STN. Compared to the separated stimulation modalities, temporally simultaneous or alternating electro-acoustic stimulation can achieve higher reductions inα-βpower for the same safety contraints on electrical/ultrasonic intensity.Significance. Focused ultrasound has the potential of becoming a non-invasive alternative of conventional DBS for the treatment of Parkinson's disease. Here, we elaborate on proposed benefits of combined electro-acoustic stimulation in terms of improved dynamic range, efficiency, spatial resolution, and neuronal selectivity.

Design and Optimization of Ultrasound Phased Arrays for Large-Scale Ultrasound Neuromodulation

Low-intensity transcranial focused ultrasound stimulation (tFUS), as a noninvasive neuromodulation modality, has shown to be effective in animals and even humans with improved millimeter-scale spatial resolution compared to its noninvasive counterparts. But conventional tFUS systems are built with bulky single-element ultrasound (US) transducers that must be mechanically moved to change the stimulation target. To achieve large-scale ultrasound neuromodulation (USN) within a given tissue volume, a US transducer array should electronically be driven in a beamforming fashion (known as US phased array) to steer focused ultrasound beams towards different neural targets. This paper presents the theory and design methodology of US phased arrays for USN at a large scale. For a given tissue volume and sonication frequency (f), the optimal geometry of a US phased array is found with an iterative design procedure that maximizes a figure of merit (FoM) and minimizes side/grating lobes (avoiding off-target stimulation). The proposed FoM provides a balance between the power efficiency and spatial resolution of a US array in USN. A design example of a US phased array has been presented for USN in a rat's brain with an optimized linear US array. In measurements, the fabricated US phased array with 16 elements (16.7×7.7×2 mm³), driven by 150 V (peak-peak) pulses at f = 833.3 kHz, could generate a focused US beam with a lateral resolution of 1.6 mm and pressure output of 1.15 MPa at a focal distance of 12 mm. The capability of the US phased array in beam steering and focusing from -60^o to 60^o angles was also verified in measurements.

The Effects of the Structural and Acoustic Parameters of the Skull Model on Transcranial Focused Ultrasound

Transcranial focused ultrasound (tFUS) has great potential in brain imaging and therapy. However, the structural and acoustic differences of the skull will cause a large number of technical problems in the application of tFUS, such as low focus energy, focal shift, and defocusing. To have a comprehensive understanding of the skull effect on tFUS, this study investigated the effects of the structural parameters (thickness, radius of curvature, and distance from the transducer) and acoustic parameters (density, acoustic speed, and absorption coefficient) of the skull model on tFUS based on acrylic plates and two simulation methods (self-programming and COMSOL). For structural parameters, our research shows that as the three factors increase the unit distance, the attenuation caused from large to small is the thickness (0.357 dB/mm), the distance to transducer (0.048 dB/mm), and the radius of curvature (0.027 dB/mm). For acoustic parameters, the attenuation caused by density (0.024 dB/30 kg/m³) and acoustic speed (0.021 dB/30 m/s) are basically the same. Additionally, as the absorption coefficient increases, the focus acoustic pressure decays exponentially. The thickness of the structural parameters and the absorption coefficient of the acoustic parameters are the most important factors leading to the attenuation of tFUS. The experimental and simulation trends are highly consistent. This work contributes to the comprehensive and quantitative understanding of how the skull influences tFUS, which further enhances the application of tFUS in neuromodulation research and treatment.

Neuroprotective Effect of Ultrasound Neuromodulation on Kainic Acid- Induced Epilepsy in Mice

Preliminary evidence suggests that low-intensity pulsed ultrasound (LIPUS) has neuroprotective effects on ischemic stroke, depression, and other conditions leading to neuronal cell death (e.g., Parkinson's disease). The purpose of this study was to investigate the neuroprotective effects of LIPUS in epileptic mice. Mice were made epileptic through kainic acid (KA) administration and then stimulated with LIPUS. The neuroprotective effect of ultrasound was evaluated by observing the latency, anxiety-like behavior, and levels of proteins related to inflammation, apoptosis, or signaling pathways. The safety of LIPUS was assessed by hematoxylin and eosin (H&E) and Nissl stainings. LIPUS prolonged the latency (Sham: 6.00 ± 0.26 days; 1-kHz pulse repetition frequency (PRF): 7.00 ± 0.31 days), improved the anxiety-like behavior, and inhibited the expression of inflammatory factors and apoptosis-related proteins. In addition, H&E and Nissl staining results confirmed that LIPUS did not damage the brain. These findings suggest that LIPUS has neuroprotective effects in mice with KA-induced epilepsy. LIPUS may offer a new therapeutic approach to epilepsy.

Neuroprotective effects of low-intensity transcranial ultrasound stimulation combined with Baicalin intervention on traumatic brain injury in animals

Low-intensity transcranial ultrasound stimulation (LITUS) can improve the inflammatory reaction after traumatic brain injury (TBI), and Baicalin also has a good protective effect on TBI. The purpose of this study was to observe the neuroprotective effect of LITUS combined with Baicalin intervention in the TBI rats. Sprague Dawley (SD) rats were randomly divided into 5 groups (n = 15) which were Sham control group, TBI group, LITUS group, Baicalin group, LITUS combined with Baicalin group (LB group). The rats were scanned with 3.0 T magnetic resonance imager, and the apparent diffusion coefficient (ADC) and the fractional anisotropy (FA) of the brain injury cortical area were determined at 3 h, 1, 3, 7 and 10 d after TBI. The ADC value, FA value, neurological function score and Nissl staining were used to assess the level of brain damage of rats. The results showed that on the 10th day after TBI, the ADC values of the TBI group, the LITUS group and the Baicalin group were remarkable greater than that of the L-B group (all adjusted P <  0.05), FA values were remarkable smaller than that of the L-B group (all adjusted P <  0.05), neurological function scores were remarkable greater than that of the L-B group (all adjusted P <  0.05), and Nissl body loss rates were remarkable greater than that of the L-B group (all adjusted P <  0.001). This study indicated that compared with the LITUS group and the Baicalin group, the L-B group can more effectively reduce level of brain damage after TBI, and the method of LITUS combined with Baicalin intervention was a more effective neuroprotection for brain injury.

Low-Intensity Pulsed Ultrasound Enhances Neurotrophic Factors and Alleviates Neuroinflammation in a Rat Model of Parkinson's Disease

Low-intensity pulsed ultrasound (LIPUS) has also been reported to improve behavioral functions in Parkinson's disease (PD) animal models; however, the effect of LIPUS stimulation on the neurotrophic factors and neuroinflammation has not yet been addressed. PD rat model was built by injection of 6-hydroxydopamine (6-OHDA) in 2 sites in the right striatum. The levels of neurotrophic factors and lipocalin-2 (LCN2)-induced neuroinflammation were quantified using a western blot. Rotational test and cylinder test were conducted biweekly for 8 weeks. When the 6-OHDA + LIPUS and 6-OHDA groups were compared, the locomotor function of the 6-OHDA + LIPUS rats was significantly improved. After LIPUS stimulation, the tyrosine hydroxylase staining density was significantly increased in the striatum and substantia nigra pars compacta (SNpc) of lesioned rats. Unilateral LIPUS stimulation did not increase brain-derived neurotrophic factor in the striatum and SNpc of lesioned rats. In contrast, unilateral LIPUS stimulation increased glial cell line-derived neurotrophic factor (GDNF) protein 1.98-fold unilaterally in the SNpc. Additionally, LCN2-induced neuroinflammation can be attenuated following LIPUS stimulation. Our data indicated that LIPUS stimulation may be a potential therapeutic tool against PD via enhancement of GDNF level and inhibition of inflammatory responses in the SNpc of the brain.