Tag: brain stimulation

Categories : Medical Research & Technology NeurologyTags :

New Flexible ‘Tentacle’ Electrodes can Precisely Record Brain Activity

On By ModernMedia
A bundle of extremely fine electrode fibres in the brain (microscope image). (Image: Yasar TB et al. Nature Communications 2024, modified)

Researchers at ETH Zurich have developed ultra-flexible brain probes that accurately record brain activity without causing tissue damage. This technology, described in Nature Communications, opens up new avenues for the treatment of a range of neurological and neuropsychiatric disorders. 

Neurostimulators, also known as brain pacemakers, send electrical impulses to specific areas of the brain via special electrodes. It is estimated that some 200 000 people worldwide are now benefiting from this technology, including those who suffer from Parkinson’s disease or from pathological muscle spasms. According to Mehmet Fatih Yanik, Professor of Neurotechnology at ETH Zurich, further research will greatly expand the potential applications: instead of using them exclusively to stimulate the brain, the electrodes can also be used to precisely record brain activity and analyse it for anomalies associated with neurological or psychiatric disorders. In a second step, it would be conceivable in future to treat these anomalies and disorders using electrical impulses.

To this end, Yanik and his team have now developed a new type of electrode that enables more detailed and more precise recordings of brain activity over an extended period of time. These electrodes are made of bundles of extremely fine and flexible fibres of electrically conductive gold encapsulated in a polymer. Thanks to a process developed by the ETH Zurich researchers, these bundles can be inserted into the brain very slowly, which is why they do not cause any detectable damage to brain tissue.

This sets the new electrodes apart from rival technologies. Of these, perhaps the best known in the public sphere is the one from Neuralink, an Elon Musk company. In all such systems, including Neuralink’s, the electrodes are considerably wider. “The wider the probe, even if it is flexible, the greater the risk of damage to brain tissue,” Yanik explains. “Our electrodes are so fine that they can be threaded past the long processes that extend from the nerve cells in the brain. They are only around as thick as the nerve-cell processes themselves.”

The tentacle electrodes (right) shown alongside three current technologies using thicker electrodes or an electrode mesh. (Yasar TB et al. Nature Communications 2024, modified)

The research team tested the new electrodes on the brains of rats using four bundles, each made up of 64 fibres. In principle, as Yanik explains, up to several hundred electrode fibres could be used to investigate the activity of an even greater number of brain cells. In the study, the electrodes were connected to a small recording device attached to the head of each rat, thereby enabling them to move freely.

No influence on brain activity

In the experiments, the research team was able to confirm that the probes are biocompatible and that they do not influence brain function. Because the electrodes are very close to the nerve cells, the signal quality is very good compared to other methods.

At the same time, the probes are suitable for long-term monitoring activities, with researchers recording signals from the same cells in the brains of animals for the entire duration of a ten-month experiment. Examinations showed that no brain-tissue damage occurred during this time. A further advantage is that the bundles can branch out in different directions, meaning that they can reach multiple brain areas.

Human testing to begin soon

In the study, the researcher used the new electrodes to track and analyse nerve-cell activity in various areas of the brains of rats over a period of several months. They were able to determine that nerve cells in different regions were “co-activated”. Scientists believe that this large-scale, synchronous interaction of brain cells plays a key role in the processing of complex information and memory formation. “The technology is of high interest for basic research that investigates these functions and their impairments in neurological and psychiatric disorders,” Yanik explains.

The group has teamed up with fellow researchers at the University College London in order to test diagnostic use of the new electrodes in the human brain. Specifically, the project involves epilepsy sufferers who do not respond to drug therapy. In such cases, neurosurgeons may remove a small part of the brain where the seizures originate. The idea is to use the group’s method to precisely localise the affected area of the brain prior to tissue removal.

Brain-machine interfaces

There are also plans to use the new electrodes to stimulate brain cells in humans. “This could aid the development of more effective therapies for people with neurological and psychiatric disorders”, says Yanik. In disorders such as depression, schizophrenia or OCD, there is often impairments in specific regions of the brain, which leads to problems in evaluation of information and decision making. Using the new electrodes, it might be possible to detect the pathological signals generated by the neural networks in the brain in advance, and then stimulate the brain in a way that would alleviate such disorders. Yanik also thinks that this technology may give rise to brain-machine interfaces for people with brain injuries. In such cases, the electrodes might be used to read their intentions and thereby, for example, to control prosthetics or a voice-output system.

Source: ETH Zurich

Categories : Mental Health NeurologyTags :

Targeted Neurostimulation Makes People More Hypnotisable

On By ModernMedia
Photo by Bruce Christianson on Unsplash

Hypnotisability appears to be a stable trait that changes little throughout adulthood, much like personality and IQ. But now, for the first time, Stanford Medicine researchers have demonstrated a way to temporarily heighten hypnotisablity, potentially allowing more people to access the benefits of hypnosis-based therapy.

In the new study, published in Nature Mental Health, the researchers found that less than two minutes of electrical stimulation targeting a precise area of the brain could boost participants’ hypnotisability for about one hour.

“We know hypnosis is an effective treatment for many different symptoms and disorders, in particular pain,” said lead author Afik Faerman, PhD, a postdoctoral scholar in psychiatry. “But we also know that not everyone benefits equally from hypnosis.”

Focused attention

Approximately two-thirds of adults are at least somewhat hypnotisable, and 15% are considered highly hypnotisable, meaning they score 9 or 10 on a standard 10-point measure of hypnotisability.

“Hypnosis is a state of highly focused attention, and higher hypnotisability improves the odds of your doing better with techniques using hypnosis,” said David Spiegel, MD, a professor of psychiatry and behavioural sciences and a senior author of the study.

Spiegel has devoted decades to studying hypnotherapy and using it to help patients control pain, lower stress, stop smoking and more. Several years ago, Spiegel led a team that used brain imaging to uncover the neurobiological basis of the practice. They found that highly hypnotisable people had stronger functional connectivity between the left dorsolateral prefrontal cortex, which is involved in information processing and decision making; and the dorsal anterior cingulate cortex, involved in detecting stimuli.

“It made sense that people who naturally coordinate activity between these two regions would be able to concentrate more intently,” Spiegel said. “It’s because you’re coordinating what you are focusing on with the system that distracts you.”

Shifting a stable trait

With these insights, Spiegel teamed up with Nolan Williams, MD, associate professor of psychiatry and behavioural sciences, who has pioneered non-invasive neurostimulation techniques to treat conditions such as depression, obsessive-compulsive disorder and suicidal ideation.

The hope was that neurostimulation could alter even a stable trait like hypnotisability.

In the new study, the researchers recruited 80 participants with fibromyalgia, a chronic pain condition that can be treated with hypnotherapy. They excluded those who were already highly hypnotisable.

Half of the participants received transcranial magnetic stimulation, in which paddles applied to the scalp deliver electrical pulses to the brain. Specifically, they received two 46-second applications that delivered 800 pulses of electricity to a precise location in the left dorsolateral prefrontal cortex. The exact locations depended on the unique structure and activity of each person’s brain.

“A novel aspect of this trial is that we used the person’s own brain networks, based on brain imaging, to target the right spot,” said Williams, also a senior author of the study.

The other half of participants received a sham treatment with the same look and feel, but without electrical stimulation. Hypnotisability was assessed by clinicians immediately before and after the treatments, with neither patients nor clinicians knowing who was in which group.

The researchers found that participants who received the neurostimulation showed a statistically significant increase in hypnotisability, scoring roughly one point higher. The sham group experienced no effect.

When the participants were assessed again one hour later, the effect had worn off and there was no longer a statistically significant difference between the two groups.

“We were pleasantly surprised that we were able to, with 92 seconds of stimulation, change a stable brain trait that people have been trying to change for 100 years,” Williams said. “We finally cracked the code on how to do it.”

The researchers plan to test whether different dosages of neurostimulation could enhance hypnotisability even more.

“It’s unusual to be able to change hypnotisability,” Spiegel said. A study of Stanford University students that began in the 1950s, for example, found that the trait remained relatively consistent when the students were tested 25 years later, as consistent as IQ over that time period. Recent research by Spiegel’s lab also suggests that hypnotisability may have a genetic basis.

Bigger implications

Clinically, a transient bump in hypnotisability may be enough to allow more people living with chronic pain to choose hypnosis as an alternative to long-term opioid use. Spiegel will follow up with the study participants to see how they fare in hypnotherapy.

The new results could have implications beyond hypnosis. Faerman noted that neurostimulation may be able to temporarily shift other stable traits or enhance people’s response to other forms of psychotherapy.

“As a clinical psychologist, my personal vision is that, in the future, patients come in, they go into a quick, non-invasive brain stimulation session, then they go in to see their psychologist,” he said. “Their benefit from treatment could be much higher.”

Story Source: Stanford Medicine