Roughly two decades ago, a strategy called optogenetics emerged to control brain activity with lasers. It uses viruses to insert genes into cells that make them sensitive to light. Optogenetics has revolutionized neuroscience by giving researchers a precise way to excite or suppress brain circuits and shed light on what role they play in the brain. However, a key drawback of this work is that it usually only targets cells that are genetically modified to respond to light. Now scientists in China have developed a new way to control brain cells using light without this limitation, potentially greatly expanding the applications of this optical approach.
Optogenetics has a number of advantages over previous methods of controlling neurons. Electrical techniques often prove bulky and invasive, triggering inflammation, while drugs often act slowly and imprecisely, with unwanted side effects. However, the fact that optogenetics works only on genetically modified cells has largely limited it to lab research.
In the new study, researchers experimented with thin-film single-crystal silicon diodes. When illuminated with lasers, the flexible photovoltaic devices could generate either positive or negative electric fields, depending on the polarity of the light.
In tests on lab-grown neurons, the silicon diodes could excite or inhibit neural activity, depending on their positive or negative voltage. In experiments on mice, the devices could also stimulate or silence neural activity in the hind leg and in the part of the brain that handles the sense of touch.
The researchers suggest these silicon films can be used in wireless, battery-free neuron stimulation by means of near-infrared light that can penetrate tissue. Potential applications include manipulating peripheral nerves for control of limb movements, the spinal cord for pain relief, the vagus nerve for treating epilepsy, and the retina for visual prosthetics, says study co-senior author Xing Sheng, a materials scientist and electrical engineer at Tsinghua University in Beijing.
The top series of images shows the natural dissolution of a silicon film on PLLA–PTMC wrapped around the sciatic nerve of mice. The bottom series shows the natural dissolution of a silicon film on the brain cortex of mice. XING SHENG
In addition, these devices are bioresorbable, meaning they naturally dissolve in the body. Therefore, brain surgery is not needed to extract them after they have accomplished any planned therapeutic goal.
“These days, brain-machine interfaces are very hot topics,” Sheng says. “However, most people focus on either the brain part—neuroscientists; or the machine part—electrical engineers. We really need more people to address the interface, which is the essential key.”
The scientists note they have not yet seen how their devices might help in models of disease. Currently, “We need to identify the most applicable scenario to use our devices and design the systems accordingly to satisfy the in vivo applications, and meet the standards for clinical grade implants,” Sheng says.
The researchers detailed their findings online 5 September in the journal Nature Biomedical Engineering.
Omicron subvariant BA.2 – which was dominant worldwide early this year, including in Hong Kong – replicates more swiftly than other strains and causes faster programmed cell death in human brains, a new study has found. [...]
The urgent need to remove excess carbon dioxide from Earth’s environment could include enlisting some of our planet’s smallest inhabitants, according to an international research team led by Michael Hochella of the Department of [...]
Blood pressure is a key vital sign that provides insight into our cardiovascular health. But blood pressure is typically measured only a few times per year by a clinician—and these measurements might not always [...]
A South African laboratory study using Covid-19 samples from an immunosupressed individual over six months showed that the virus evolved to become more pathogenic, indicating that a new variant could cause worse illness than [...]
For the past several months, Omicron subvariants BA.4 and BA.5 have dominated COVID-19 cases in the U.S. But now, there’s a class of new COVID subvariants on the rise and one in particular is getting plenty of [...]
Nucleic acid therapies involving DNA or RNA have significant potential to treat genetic disorders, infectious diseases, and cancer; however, research suggests that less than 1% of injected nucleic acid doses reach target cells in [...]
The US Food and Drug Administration on Tuesday approved Hemgenix, a new drug to treat hemophilia. Manufacturer CSL Behring set the price at $3.5 million per treatment, making it the most expensive drug [...]
Some wounds just won’t heal. Infections, diseases like diabetes, and suppressed immune systems often stack up to slow healing. Chronic wounds can last months and lead to anxiety and depression. In the worst cases, [...]
Over the years, researchers have tried hard to comprehend topographic signals that promote cell mechanical sensitive responses. The extracellular matrix (ECM) provides a complex cellular microenvironment that controls cellular behavior. Nevertheless, only a few [...]
There is now an imminent threat of measles spreading in various regions globally, as COVID-19 led to a steady decline in vaccination coverage and weakened surveillance of the disease, the World Health Organization (WHO) [...]
In a recent study, it was shown that people with long Covid have had physical changes to their brains several months after experiencing the initial infection. The study included MRIs of patients who continued [...]
Western University in London, Ont., is building a unique research lab to study humanity's greatest viral threats — a secret weapon, if you will, one that it's expected would put Canada and the world in a better position if [...]
Cancer patients are testing a medicine made of antibodies that were designed from scratch on a computer in Israel and whose inventor has “programmed” them to “decide” whether cells surrounding tumors are bad or good. [...]
In an article published in the journal Scientific Reports, researchers presented the potentiostatic deposition used to electrodeposit nickel (Ni) and nickel-graphene (Ni-G) films on copper substrates. Myristic acid (MA) was employed to alter the plane of the [...]
Oregon State University scientists have invented a way to make magnetic nanoparticles that get hotter than any previous nanoparticle, improving their cancer fighting ability. Faculty from the OSU College of Pharmacy spearheaded a collaboration [...]