Tag: deep brain stimulation

Categories : Implants and Prostheses NeurologyTags :

Tiny Magnetic Discs Offer Remote Brain Stimulation without Genetic Modifications

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The magnetic core of the nanodisc is magnetostrictive, which means it changes shape when magnetised. The rainbow nanodisc on the right is changing shape, allowing for the pink brain neuron to be stimulated. Image: Courtesy of the researchers

Novel magnetic nanodiscs could provide a much less invasive way of stimulating parts of the brain, paving the way for stimulation therapies without implants or genetic modification, MIT researchers report in Nature Nanotechnology.

The scientists envision that the tiny discs – about 250nm across – would be injected directly into the chosen brain location. From there, they could be activated at any time simply by applying an external magnetic field. The new particles could quickly find applications in biomedical research, and eventually, after sufficient testing, might be applied to clinical uses.

The research is described in the paper by Polina Anikeeva, a professor in MIT’s departments of Materials Science and Engineering and Brain and Cognitive Sciences, graduate student Ye Ji Kim, and 17 others at MIT and in Germany.

Deep brain stimulation (DBS) uses electrodes implanted in the target brain regions to treat symptoms of neurological and psychiatric conditions such as Parkinson’s disease and obsessive-compulsive disorder. Despite its efficacy, the surgical difficulty and clinical complications associated with DBS limit the number of cases where such an invasive procedure is warranted. The new nanodiscs could provide a much more benign way of achieving the same results.

Over the past decade other implant-free methods of producing brain stimulation have been developed, but were limited by spatial resolution or access. Other magnetic approaches studied needed genetic modifications to work, ruling it out for humans.

Since all nerve cells are sensitive to electrical signals, Kim, a graduate student in Anikeeva’s group, hypothesised that a magnetoelectric nanomaterial that can efficiently convert magnetisation into electrical potential could offer a path toward remote magnetic brain stimulation.

To this end, the researchers created nanodiscs with a magnetic core and piezolectric shell. When the core was squeezed by a magnetic field, strain in the shell produces a varying electrical polarisation. This enables the particles to deliver electrical pulses to neurons. The disc shape enhances the magnetostriction effect more than 1000-fold compared to spherical particles used previously.

After testing the nanodiscs with neurons in vitro, the researchers then injected small droplets of nanodisc-bearing solution into specific regions of the brains of mice. With an electromagnet, they turned on and off the stimulation in that region. That electrical stimulation “had an impact on neuron activity and on behaviour,” Kim says.

The team found that the magnetoelectric nanodiscs could stimulate a deep brain region, the ventral tegmental area, that is associated with feelings of reward.

The team also stimulated another brain area, the subthalamic nucleus, associated with motor control. “This is the region where electrodes typically get implanted to manage Parkinson’s disease,” Kim explains. The researchers were able to successfully demonstrate the modulation of motor control through the particles. Specifically, by injecting nanodiscs only in one hemisphere, the researchers could induce rotations in healthy mice by applying magnetic field.

The nanodiscs could trigger the neuronal activity comparable with conventional implanted electrodes delivering mild electrical stimulation. The authors achieved subsecond temporal precision for neural stimulation with their method yet observed significantly reduced foreign body responses as compared to the electrodes, potentially allowing for even safer deep brain stimulation.

The multilayered chemical composition and physical shape and size of the new multilayered nanodiscs is what made precise stimulation possible.

While the researchers successfully increased the magnetostrictive effect, the second part of the process, converting the magnetic effect into an electrical output, still needs more work, Anikeeva says. While the magnetic response was a thousand times greater, the conversion to an electric impulse was only four times greater than with conventional spherical particles.

“This massive enhancement of a thousand times didn’t completely translate into the magnetoelectric enhancement,” says Kim. “That’s where a lot of the future work will be focused, on making sure that the thousand times amplification in magnetostriction can be converted into a thousand times amplification in the magnetoelectric coupling.”

Further work is need before studies involving humans can begin, Kim says.

Source: MIT

Categories : Implants and Prostheses NeurologyTags :

DBS Immediately Improves Arm and Hand Function After a Brain Injury

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Deep brain stimulation illustration. Credit: NIH

Deep brain stimulation (DBS) may provide immediate improvement in arm and hand strength and function weakened by traumatic brain injury or stroke, according to research from the University of Pittsburgh School of Medicine.

Encouraging results from extensive tests in monkeys and humans open a path for a new clinical application of an already widely used brain stimulation technology and offer insights into neural mechanisms underlying movement deficits caused by brain injury. The results are published in Nature Communications.

“Arm and hand paralysis significantly impacts the quality of life of millions of people worldwide,” said senior and corresponding author Elvira Pirondini, Ph.D., assistant professor of physical medicine and rehabilitation at Pitt. “Currently, we don’t have effective solutions for patients who suffered a stroke or traumatic brain injury but there is a growing interest in the use of neurotechnologies that stimulate the brain to improve upper-limb motor functions.”

Brain lesions caused by serious brain trauma or stroke can disrupt neural connections between the motor cortex, a key brain region essential for controlling voluntary movement, and the muscles. Weakening of these connections prevents effective activation of muscles and results in movement deficits, including partial or complete arm and hand paralysis.

To boost the activation of existing, but weakened, connections, researchers proposed to use deep brain stimulation (DBS), a surgical procedure that involves placing tiny electrodes in specific areas of the brain to deliver electrical impulses that regulate abnormal brain activity. Over the past several decades, DBS has revolutionised the treatment of neurological conditions such as Parkinson’s disease by providing a way to control symptoms that were once difficult to manage with medication alone. 

“DBS has been life-changing for many patients. Now, thanks to ongoing advancements in the safety and precision of these devices, DBS is being explored as a promising option for helping stroke survivors recover their motor functions,” said senior author Jorge González-Martínez, MD, PhD, neurosurgery professor at Pitt. “It offers new hope to millions of people worldwide.” 

Taking cues from another successful Pitt project that used electrical stimulation of the spinal cord to restore arm function in individuals affected by stroke, scientists hypothesised that stimulating the motor thalamus – a key relay hub of movement control – using DBS could help restore movements that are essential for tasks of daily living, such as object grasping. However, because the theory has not been tested before, they first had to test it in monkeys, which are the only animals that have the same organization of the connections between the motor cortex and the muscles as humans. 

To understand the mechanism of how DBS of the motor thalamus helps improve voluntary arm movement and to finesse the specific location of the implant and the optimal stimulation frequency, researchers implanted the FDA-approved stimulation device into monkeys that had brain lesions affecting how effectively they could use their hands. 

As soon as the stimulation was turned on, it significantly improved activation of muscles and grip force. Importantly, no involuntary movement was observed.

To verify that the procedure could benefit humans, the same stimulation parameters were used in a patient who was set to undergo DBS implantation into the motor thalamus to help with arm tremors caused by brain injury from a serious motor vehicle accident that resulted in severe paralysis in both arms.

As soon as the stimulation was turned on again, the range and strength of arm motion was immediately improved: The participant was able to lift a moderately heavy weight and reach, grasp and lift a drinking cup more efficiently and smoothly than without the stimulation.

To help bring this technology to more patients in the clinic, researchers are now working to test the long-term effects of DBS and determine whether chronic stimulation could further improve arm and hand function in individuals affected by traumatic brain injury or stroke.

Source: University of Pittsburgh

Categories : Implants and Prostheses Neurodegenerative DiseasesTags :

Taming Parkinson’s Disease with Adaptive Deep Brain Stimulation

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Deep brain stimulation illustration. Credit: NIH

Two new studies from UC San Francisco are pointing the way toward round-the-clock personalised care for people with Parkinson’s disease through an implanted device that can treat movement problems during the day and insomnia at night. 

The approach, called adaptive deep brain stimulation, or aDBS, uses methods derived from AI to monitor a patient’s brain activity for changes in symptoms. 

When it spots them, it intervenes with precisely calibrated pulses of electricity. The therapy complements the medications that Parkinson’s patients take to manage their symptoms, giving less stimulation when the drug is active, to ward off excess movements, and more stimulation as the drug wears off, to prevent stiffness.

It is the first time a so-called “closed loop” brain implant technology has been shown to work in Parkinson’s patients as they go about their daily lives. The device picks up brain signals to create a continuous feedback mechanism that can curtail symptoms as they arise. Users can switch out of the adaptive mode or turn the treatment off entirely with a hand-held device.

For the first study, researchers conducted a clinical trial with four people to test how well the approach worked during the day, comparing it to an earlier brain implant DBS technology known as constant or cDBS. 

To ensure the treatment provided the maximum relief to each participant, the researchers asked them to identify their most bothersome symptom. The new technology reduced them by 50%. Results appear August 19 in Nature Medicine.

“This is the future of deep brain stimulation for Parkinson’s disease,” said senior author Philip Starr, MD, PhD, the Dolores Cakebread Professor of Neurological Surgery, co-director of the UCSF Movement Disorders and Neuromodulation Clinic. 

Starr has been laying the groundwork for this technology for more than a decade. In 2013, he developed a way to detect and then record the abnormal brain rhythms associated with Parkinson’s. In 2021, his team identified specific patterns in those brain rhythms that correspond to motor symptoms.

“There’s been a great deal of interest in improving DBS therapy by making it adaptive and self-regulating, but it’s only been recently that the right tools and methods have been available to allow people to use this long-term in their homes,” said Starr, who was recruited by UCSF in 1998 to start its DBS program.

Earlier this year, UCSF researchers led by Simon Little, MBBS, PhD, demonstrated in Nature Communications that adaptive DBS has the potential to alleviate the insomnia that plagues many patients with Parkinson’s. 

“The big shift we’ve made with adaptive DBS is that we’re able to detect, in real time, where a patient is on the symptom spectrum and match it with the exact amount of stimulation they need,” said Little, associate professor of neurology and a senior author of both studies. Both Little and Starr are members of the UCSF Weill Institute for Neurosciences.

Restoring movement

Parkinson’s disease affects about 10 million people around the world. It arises from the loss of dopamine-producing neurons in deep regions of the brain that are responsible for controlling movement. The lack of those cells can also cause non-motor symptoms, affecting mood, motivation and sleep.

Treatment usually begins with levodopa, a drug that replaces the dopamine these cells are no longer able to make. However, excess dopamine in the brain as the drug takes effect can cause uncontrolled movements, called dyskinesia. As the medication wears off, tremor and stiffness set in again.  

Some patients then opt to have a standard cDBS device implanted, which provides a constant level of electrical stimulation. Constant DBS may reduce the amount of medication needed and partially reduce swings in symptoms. But the device also can over- or undercompensate, causing symptoms to veer from one extreme to the other during the day.

Closing the loop

To develop a DBS system that could adapt to a person’s changing dopamine levels, Starr and Little needed to make the DBS capable of recognising the brain signals that accompany different symptoms. 

Previous research had identified patterns of brain activity related to those symptoms in the subthalamic nucleus, or STN, the deep brain region that coordinates movement. This is the same area that cDBS stimulates, and Starr suspected that stimulation would mute the signals they needed to pick up.

So, he found alternative signals elsewhere in the brain – the motor cortex – that wouldn’t be weakened by the DBS stimulation. 

The next challenge was to work out how to develop a system that could use these dynamic signals to control DBS in an environment outside the lab. 

Building on findings from adaptive DBS studies that he had run at Oxford University a decade earlier, Little worked with Starr and the team to develop an approach for detecting these highly variable signals across different medication and stimulation levels.  

Over the course of many months, postdoctoral scholars Carina Oerhn, PhD, Lauren Hammer, PhD, and Stephanie Cernera, PhD, created a data analysis pipeline that could turn all of this into personalised algorithms to record, analyse and respond to the unique brain activity associated with each patient’s symptom state.

John Ngai, PhD, who directs the Brain Research Through Advancing Innovative Neurotechnologies® initiative (The BRAIN Initiative®) at the National Institutes of Health, said the study promises a marked improvement over current Parkinson’s treatment. 

“This personalised, adaptive DBS embodies The BRAIN Initiative’s core mission to revolutionise our understanding of the human brain,” he said. 

A better night’s sleep

Continuous DBS is aimed at mitigating daytime movement symptoms and doesn’t usually alleviate insomnia.

But in the last decade, there has been a growing recognition of the impact that insomnia, mood disorders and memory problems have on Parkinson’s patients. 

To help fill that gap, Little conducted a separate trial that included four patients with Parkinson’s and one patient with dystonia, a related movement disorder. In their paper published in Nature Communications, first author Fahim Anjum, PhD, a postdoctoral scholar in the Department of Neurology at UCSF, demonstrated that the device could recognise brain activity associated with various states of sleep. He also showed it could recognise other patterns that indicate a person is likely to wake up in the middle of the night. 

Little and Starr’s research teams, including their graduate student Clay Smyth, have started testing new algorithms to help people sleep. Their first sleep aDBS study was published last year in Brain Stimulation.  

Scientists are now developing similar closed-loop DBS treatments for a range of neurological disorders. 

“We see that it has a profound impact on patients, with potential not just in Parkinson’s but probably for psychiatric conditions like depression and obsessive-compulsive disorder as well,” Starr said. “We’re at the beginning of a new era of neurostimulation therapies.”

Source: University of California San Francisco

Categories : NeurologyTags :

New Non-invasive Brain Stimulation may One Day Treat Addiction, Depression and OCD

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Source: CC0

Neurological disorders, such as addiction, depression, and obsessive-compulsive disorder (OCD), affect millions of people worldwide and are often characterised by complex pathologies involving multiple brain regions and circuits. These conditions are notoriously difficult to treat due to the intricate and poorly understood nature of brain functions and the challenge of delivering therapies to deep brain structures without invasive procedures.

In the rapidly evolving field of neuroscience, non-invasive brain stimulation enables the understanding and treating a myriad of neurological and psychiatric conditions, free of surgery or implants. Researchers, led by Friedhelm Hummel, who holds the Defitchech Chair of Clinical Neuroengineering at EPFL’s School of Life Sciences, and postdoc Pierre Vassiliadis, are pioneering a new approach in the field.

Their research, which is described in Nature Human Behaviour, makes use of transcranial Temporal Interference Electric Stimulation (tTIS). The approach specifically targets deep brain regions serving as control centres of several important cognitive functions and involved in different neurological and psychiatric pathologies.

“Invasive deep brain stimulation (DBS) has already successfully been applied to the deeply seated neural control centers in order to curb addiction and treat Parkinson, OCD or depression,” says Hummel. “The key difference with our approach is that it is non-invasive, meaning that we use low-level electrical stimulation on the scalp to target these regions.”

The innovative technique is based on the concept of temporal interference, initially explored in rodent models, and now successfully translated to human applications by the EPFL team. In this experiment, one pair of electrodes is set to a frequency of 2000Hz, while another is set to 2080Hz. Thanks to detailed computational models of the brain structure, the electrodes are specifically positioned on the scalp to ensure that their signals intersect in the target region.

It is at this juncture that the magic of interference occurs: the slight frequency disparity of 80Hz between the two currents becomes the effective stimulation frequency within the target zone. The brilliance of this method lies in its selectivity; the high base frequencies (eg, 2000Hz) do not stimulate neural activity directly, leaving the intervening brain tissue unaffected and focusing the effect solely on the targeted region.

The focus of this latest research is the human striatum, a key player in reward and reinforcement mechanisms. “We’re examining how reinforcement learning, essentially how we learn through rewards, can be influenced by targeting specific brain frequencies,” says Vassiliadis. By applying stimulation of the striatum at 80Hz, the team found they could disrupt its normal functioning, directly affecting the learning process.

The therapeutic potential of their work is immense, particularly for conditions like addiction, apathy and depression, where reward mechanisms play a crucial role. “In addiction, for example, people tend to over-approach rewards. Our method could help reduce this pathological overemphasis,” Vassiliadis, who is also a researcher at UCLouvain’s Institute of Neuroscience, points out.

Vassiliadis, lead author of the paper, a medical doctor with a joint PhD, describes tTIS as using two pairs of electrodes attached to the scalp to apply weak electrical fields inside the brain. “Up until now, we couldn’t specifically target these regions with non-invasive techniques, as the low-level electrical fields would stimulate all the regions between the skull and the deeper zones – rendering any treatments ineffective. This approach allows us to selectively stimulate deep brain regions that are important in neuropsychiatric disorders,” he explains.

Furthermore, the team is exploring how different stimulation patterns can not only disrupt but also potentially enhance brain functions. “This first step was to prove the hypothesis of 80Hz affecting the striatum, and we did it by disrupting it’s functioning. Our research also shows promise in improving motor behaviour and increasing striatum activity, particularly in older adults with reduced learning abilities,” Vassiliadis adds.

Hummel, a trained neurologist, sees this technology as the beginning of a new chapter in brain stimulation, offering personalised treatment with less invasive methods. “We’re looking at a non-invasive approach that allows us to experiment and personalise treatment for deep brain stimulation in the early stages,” he says. Another key advantage of tTIS is its minimal side effects. Most participants in their studies reported only mild sensations on the skin, making it a highly tolerable and patient-friendly approach.

Hummel and Vassiliadis are optimistic about the impact of their research. They envision a future where non-invasive neuromodulation therapies could be readily available in hospitals, offering a cost-effective and expansive treatment scope.

Original written by Michael David Mitchell. The original text of this story is licensed under Creative Commons CC BY-SA 4.0. Edited for style and length.

Source: Ecole Polytechnique Fédérale de Lausanne

Categories : Neurodegenerative DiseasesTags :

Surgery-free Deep Brain Stimulation Could be New Treatment for Dementia

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A new form of deep brain stimulation offers hope for an alternative treatment option for dementia, without the need for surgery.

Researchers at Imperial College London are leading the development of the technique, known as temporal interference (TI). This non-invasive method works by delivering electrical fields to the brain through electrodes placed on the patient’s scalp and head. Their initial findings, which are published in the journal Nature Neuroscience, could lead to an alternative treatment for brain diseases such as Alzheimer’s, and its associated memory loss.

Temporal interference

By targeting the overlapping electrical fields researchers were able to stimulate an area deep in the brain called the hippocampus, without affecting the surrounding areas – a procedure that until now required surgery to implant electrodes into the brain.

The approach has been successfully trialled with 20 healthy volunteers for the first time by a team at the UK Dementia Research Institute (UK DRI) at Imperial and the University of Surrey.

Their initial results show that when healthy adults perform a memory task whilst receiving TI stimulation it helped to improve memory function.

The team is now conducting a clinical trial in people with early-stage Alzheimer’s disease, where they hope TI could be used to improve symptoms of memory loss.

Dr Nir Grossman, from the Department of Brain Sciences at Imperial College London, who led the work said: “Until now, if we wanted to electrically stimulate structures deep inside the brain, we needed to surgically implant electrodes which of course carries risk for the patient, and can lead to complications.

“With our new technique we have shown for the first time, that it is possible to remotely stimulate specific regions deep within the human brain without the need for surgery. This opens up an entirely new avenue of treatment for brain diseases like Alzheimer’s which affect deep brain structures.”

Reaching deep brain regions

TI was first described by the team at Imperial College London in 2017 and shown to work in principle in mice.

This latest work, funded and carried out through the UK Dementia Research Institute, shows for the first time that TI is effective at stimulating regions deep within the human brain.

According to the researchers, this could have broad applications and will enable scientists to stimulate different deep brain regions to discover more about their functional roles, accelerating the discovery of new therapeutic targets.

Source: Imperial College London

Categories : Implants and Prostheses NeurologyTags :

For Stroke Recovery, Deep Brain Stimulation may Aid Rehabilitation

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Deep brain stimulation illustration. Credit: NIH

A first-in-human trial of deep brain stimulation (DBS) for post-stroke rehabilitation patients has shown that using DBS to target the dentate nucleus – which regulates fine-control of voluntary movements, cognition, language, and sensory functions in the brain – is safe and feasible.

The EDEN trial (Electrical Stimulation of the Dentate Nucleus for Upper Extremity Hemiparesis Due to Ischemic Stroke) also shows that the majority of participants (9 of 12) demonstrated improvements in both motor impairment and function. Importantly, the study found that participants with at least minimal preservation of distal motor function at enrolment showed gains that almost tripled their initial scores.

Published in Nature Medicine, these findings build on more than a decade of preclinical work led by principal investigators Andre Machado, MD, PhD, and Kenneth Baker, PhD, at Cleveland Clinic.

“These are reassuring for patients as the participants in the study had been disabled for more than a year and, in some cases, three years after stroke. This gives us a potential opportunity for much needed improvements in rehabilitation in the chronic phases of stroke recovery,” said Dr Machado, patented the DBS method in stroke recovery. “The quality-of-life implications for study participants who responded to therapy have been significant.”

“We saw patients in the study regain levels of function and independence they did not have before enrolling in the research,” Dr Machado said. “This was a smaller study and we look forward to expanding as we have begun the next phase.”

The completed EDEN trial enrolled 12 individuals with chronic, moderate-to-severe hemiparesis of the upper extremity as a result of a unilateral middle cerebral artery stroke 12-to-36 months prior. There were no major complications throughout the study. Nine of the 12 participants improved to a degree that is considered meaningful in stroke rehabilitation.

Source: Cleveland Clinic

Categories : NeurologyTags :

Scientists Unravel Neurological Origins of the Placebo Effect

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Researchers at Massachusetts General Hospital (MGH) have discovered a network of brain regions activated by the placebo effect overlaps with several regions targeted by brain-stimulation therapy for depression.

The findings of this study, published in Molecular Psychiatry, will help in understanding the neurobiology of placebo effects and could inform how brain stimulation trial results are interpreted. In addition, this could provide insights on how to harness placebo effects for the treatment of a variety of conditions.

The placebo effect occurs when a patient’s symptoms improve because they expect a therapy to help (due to a variety of factors), but not from the specific effects of the treatment itself. Recent research indicates that there is a neurological basis for the placebo effect, with imaging studies identifying a pattern of changes that happen in certain brain regions when a person experiences this phenomenon.

The use of brain-stimulation techniques for patients with depression that doesn’t respond adequately to medication or psychotherapy has gained wider use in recent years. Transcranial magnetic stimulation (TMS) delivers electromagnetic pulses to the brain, and its effect on brain activity has been established over the last three decades in animal and human research studies, with several TMS devices approved by the Food and Drug Administration for treating depression. In addition, for treatment depression, deep brain stimulation (DBS, which requires an implanted device) has shown some promise.

Senior author Emiliano Santarnecchi, PhD, saw studies of brain stimulation as a unique opportunity to learn more about the neurobiology of the placebo effect. Santarnecchi and his co-investigators conducted a meta-analysis and review of neuroimaging studies involving healthy subjects and patients to create a “map” of brain regions activated by the placebo effect. They also analysed studies of people treated with TMS and DBS for depression to identify brain regions targeted by the therapies. The team found that several sites in the brain that are activated by the placebo effect overlap with brain regions targeted by TMS and DBS.

Dr Santarnecchi and his colleagues believe that this overlap has critical importance in interpreting the results of research on brain stimulation for conditions such as depression. In clinical trials, a significant portion of depression patients receiving brain stimulation improve — but so do many patients receiving placebo (sham) treatment, in which no stimulation is administered, which has led to confusion over the therapy’s benefits.

A possible explanation is “that there is a significant placebo effect when you do any form of brain stimulation intervention,” said Dr Santarnecchi. TMS involves a clinical setting, with loud clicks as the pulse is delivered. “So the patient thinks, ‘Wow, they are really activating my brain’, so you get a lot of expectation,” said Dr Santarnecchi.

Elevated placebo effects associated with brain stimulation may create problems when studying the intervention, said first author Matthew Burke, MD, a cognitive neurologist. If brain stimulation and the placebo effect overlap in activating the same brain regions, then those circuits could be maximally activated by placebo effects, which could make it difficult to show any additional benefit from TMS or DBS, said Dr Burke. If so, this could explain the disparity of results in neurostimulation treatment of depression. Screening out placebo from brain stimulation’s direct impact on brain activity will help in designing studies where the real potential of techniques such as TMS will be more easily quantified, thus improving the effect of treatment protocols.

The findings from this study also suggest broad applications for the placebo effect, said Dr Santarnecchi. “We think this is an important starting point for understanding the placebo effect in general, and learning how to modulate and harness it, including using it as a potential therapeutic tool by intentionally activating brain regions of the placebo network to elicit positive effects on symptoms,” he said.

Dr Santarnecchi and his colleagues are currently designing trials that they hope will “disentangle” the effects of brain stimulation from placebo effects and offer insights about how they can be leveraged in clinical settings.

Source: Massachusetts General Hospital