2024-01-14 15:05:00
A brain or neuronal implant that provides information on the deep activity of the brain while remaining on its surface has just been developed by researchers at the University of California at San Diego (USA). This implant, composed of a thin, transparent and flexible polymer strip, is equipped with a dense network of graphene electrodes.
Tested in transgenic mice, this technology brings researchers one step closer to creating a minimally invasive brain-computer interface (BCI) that provides high-resolution data on deep neuronal activity using recordings from the surface of the brain.
Innovative technology
The new neural implant developed atUC San Diego offers the best of both worlds. The implant is a thin, transparent, flexible strip of polymer that conforms to the surface of the brain. The band is inlaid with a high density network of tiny circular graphene electrodes, each measuring 20 micrometers in diameter. Each electrode is connected by a graphene wire of a few micrometers to a printed circuit board.
When placed on the surface of the brain, the implant records electrical signals from neurons in the outer layers. At the same time, the researchers used a two-photon microscope to shine laser light through the implant to obtain images of the calcium spikes of neurons up to 250 micrometers below the surface.
Close-up of the graphene electrode array. Crédit : David Baillot/UC San Diego Jacobs School of Engineering
Promising results
The researchers found a correlation between surface electrical signals and calcium spikes in deeper layers. This correlation allowed researchers to use surface electrical signals to train neural networks to predict calcium activity – not only for large populations of neurons, but also for individual neurons – at various depths.
An advantage of being able to predict calcium activity from electrical signals is that it overcomes the limitations of imaging experiments. When imaging calcium spikes, the subject’s head must be fixed under a microscope. These experiences may only last an hour or two at a time.
Synthetic
For a better understanding
What is a neural implant?
A neural implant is a medical device designed to stimulate, record or block signals in the brain. These implants can be used to treat a variety of neurological disorders, such as Parkinson’s disease, epilepsy and depression.
What is a brain-computer interface?
A brain-computer interface (BCI) is a system that allows direct communication between the brain and an external device. BCIs are used in biomedical research and neuroprosthetics, but they also have potential applications in defense fields.
What is graphene?
Graphene is an allotropic form of carbon consisting of a single plane of carbon atoms arranged in a hexagonal lattice. It is extremely strong, lightweight, transparent and conductive, making it useful in a variety of applications, from electronics to medicine.
What is calcium activity in the brain?
Calcium activity in the brain refers to fluctuations in calcium concentrations in neurons, which play a key role in how neurons communicate with each other. Calcium activity can be measured using special imaging techniques.
What are the advantages of this new technology?
This new technology provides high-resolution information about deep neuronal activity, which could improve our understanding of the brain and help develop new therapies for neurological disorders.
References
Illustration: Placed on the surface of the brain, this thin, flexible implant allows researchers to collect high-resolution information on neuronal activity inside the brain without damaging its delicate tissues. Credit: David Baillot/UC San Diego Jacobs School of Engineering
Article “High-density Transparent Graphene Arrays for Predicting Cellular Calcium Activity at Depth from Surface Potential Recordings” – DOI: 10.1038/s41565-023-01576-z
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