China researchers build neuron-enlarging brain device using genetic engineering

Chinese scientists have proposed that genetic engineering could one day be used to alter the brain’s neurons as a way of improving the quality of signal transmission in brain-computer interface (BCI) technology.The researchers, with the Chinese Academy of Sciences’ National Centre for Nanoscience and Technology (NCNST), implanted sensors into a mouse’s brain that carried a genetic instruction to make the neurons larger and easier to “read”.

According to the study published in peer-reviewed journal Advanced Materials, the experiments showed the implant – which suppresses the expression of genes that restrict neuron growth – improved brain cell health as well as BCI connections.The researchers said the results showed the approach could one day improve the quality of signal transmission in existing BCI technologies – such as Elon Musk’s Neuralink – in therapeutic settings and in using the mind to directly control devices.

Rapid advances in technology have made it possible for users to control mechanical arms and even computer cursors through thought alone. BCI also offers promising therapeutic benefits to paralysis patients by restoring some motor functions.But while non-invasive BCIs use wearable devices to record and interpret brain signals through the scalp, signal resolution is low and they cannot interact directly with neurons.

To overcome these limitations, researchers in the field have increasingly turned to semi-invasive and invasive BCIs, which involve surgically implanting electrodes and chips into the brain’s cortex to capture high-quality neural signals.Although this method provides clearer signals, there are safety as well as ethical concerns. Surgery can lead to complications, while conventional neural probes – made from rigid materials like silicon or metals – are a mismatch with soft brain tissues.

Neuralink responded to the latter challenge by developing a BCI chip containing 64 flexible polymer threads. Earlier this year, a patient with quadriplegia received one of the chips, in the first human trial of the technology.The device’s functionality began to decrease less than a month after surgery when some of the chip’s threads “retracted from the brain”. Neuralink said its engineers were able to refine the implant and restore functionality.

Chinese researchers claim brain-computer interface breakthrough using monkey brain signal
Fang Ying, a co-author of the Chinese study, noted that most research has focused on “developing biocompatible neural electrodes by structural engineering to minimise tissue rejection and enhance the long-term stability of BCI”. “We propose using genetic engineering technologies to enhance the survival and growth of the neuronal cells/tissue surrounding the electrodes, potentially boosting BCI performance,” she said, in an interview published on the Chinese Academy of Sciences website.

Fang and her team proposed an electrode that resembles a slender comb, only 3 microns thick and made from a flexible and biocompatible polymer, in a similar approach to the one taken by Neuralink.The comb features eight teeth uniformly distributed with 120 recording and reference electrodes, each functioning like a protruding microphone to collect signals from nearby neurons.

Tian Huihui, one of the study’s corresponding authors and a research assistant at NCNST, said “years of research and testing” had shown that the polyamide electrodes “can stably transmit signals for over a year in vivo”.The team’s innovation was to coat the electrodes with a layer of a drug carrier containing a small RNA genetic sequence that is released after implantation to influence the surrounding neuronal and other cells.

“We knock down specific genes in the brain precisely. For example, we knocked down PTEN in neuronal cells around the implanted BCI device. The downregulation leads to an enlargement of neuronal cell bodies at the electrode-tissue interface, positively affecting neuronal health and potentially enhancing the interface’s performance,” Tian said.“The enhanced condition and increased number of neurons near the electrodes significantly improve the quality of the collected signals, which is highly beneficial for subsequent decoding of neural signals.”

The team implanted electrodes in both sides of the same mouse brain to exclude the many individualised factors that can affect performance, such as surgical conditions, differences in immune rejection, and neural signal strength.“With quantitative analysis, we found that the number of neurons was significantly higher and the neural activity was more frequent on the side of the brain where the gene was knocked down,” Tian said.

“Also, the soma size of neurons 12 weeks after implantation on the knockdown side was 20 per cent higher than the control side. ”Despite ethical concerns preventing its application in larger animals like macaques – let alone genetic modification of the human brain – the researchers are confident that their method expands the use of genetic engineering in enhanced BCIs.

The breakthrough shows the precise transfection of cells at the neural interface, according to the paper. “Our system holds significant promise in clinical applications, especially in the fields of highly precise genetic engineering,” Fang said. “It paves the way for the next generation of BCI.”