Radical 'brain mesh' that could make the Matrix a reality

Radical 'brain mesh' that could make the Matrix a reality

Brain implants are a popular feature of science fiction movies, but now, researchers may be closer to making them a reality.

Researchers at Harvard University have developed an injectable brain mesh that can directly record changes in electrical signals in the brain, down to the level of a single brain cell.

The mesh probe could have a wide range of applications, including brain-machine interfaces, cyborg animals and could also provide insight on how memory and learning evolve with age and age-related diseases such as Alzheimer's disease. 

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Schematic of the mesh electronic technology. (B) Free-standing mesh electronics floating in aqueous solution and ready to be loaded into a glass needle. (C) Mesh electronics injected into mouse brain, with part of the mesh sagging between the brain and the needle

HOW IT WORKS  

The probeâ€"which does not require a power supplyâ€"directly records neural voltage changes by being able to interface with all regions of the brain from the level of single neuron through circuits and networks.

The mesh recording electrode is connected by metal lines to pads at the opposite end of the mesh. 

These pads are connected to Flat Flexible Cabl es (FFC) and plugged in an external system for recording.

In tests in mice, the injectable probe produced a minimal, short-lived immune response and the mesh and brain tissue merged with the probe. 

In tests in mice, the injectable probe produced a minimal, short-lived immune response and the mesh and brain tissue merged with the probe. 

By adding stimulation electrodes, the researchers can obtain high level feedback to overcome cognitive declines associated with aging.  

The protocol for this experiment, originally published in 2015, described an ultraflexible mesh brain probe delivered to specific brain regions via a syringe. 

The mesh recording electrode is connected by metal lines to pads at the opposite end of the mesh. 

These pads are connected to Flat Flexible Cabl es (FFC) and plugged in an external system for recording.  

The researchers say that while the probe may never need to be removed and could remain as a lifelong implant, removal would be a straightforward, if not issue-free procedure.

Dr Charles Lieber, a professor of chemistry at Harvard University and co-author of the research, told Phys.org that by designing a mesh probe that can be implanted precisely, with properties similar to neural tissue, 'we eliminate chronic immune response that is found with all other probes and medical implants, which are more like thorns in your tissue.'

In tests in mice , the injectable probe produced a minimal, short-lived immune response and the mesh and brain tissue merged with the probe. By adding stimulation electrodes, the researchers can obtain feedback to overcome cognitive declines associated with aging

Dr Lieber says the research opens up a new field with opportunities for further study, for example co-injection of electronics and cells where mesh electronics also serve as a scaffold for tissue to grow, which is relevant in the field of regenerative medicine.

The researchers made the mesh using a technique called photolithography - which uses light to construct microscopic structures. 

(D) Schematic of mesh electronics implanted in brain tissue with horizontal (yellow plane) and sagittal (green plane) sectioning directions highlighted in the inset. (E) Schematics of the interface between mesh electronics and the brain tissue (Left, cross-section view) and that between flexible thin-film technology and the brain tissue (Right, cross-section view). Mesh elements and the flexible thin-film are highlighted in blue, neurons are in purple, and glial (cell) scars are in yellow

The mesh is made of polymide - a polymer material that is highly heat-resistant and can be used for a wide range of applications such as high temperature fuel cells, displays and even military roles. 

To measure the immune response caused by the probe, the researchers sectioned mouse brains into cross-sectional and longitudinal slices. 

They were able to do thi s without removing the implantable probe, which Dr Lieber says usually needs to be done in most cases involving conventional brain probes - and this procedure can result in some loss of critical information. 

After staining the brain slices with antibodies, they found that the immune response was minimal and brain cell structure returned to normal after only a couple of weeks. 

To measure the immune response caused by the probe, the researchers sectioned mouse brains into cross-sectional and longitudinal slices. Pictured are microscope images of brain tissue slices from the mesh electronics technology (top row) versus flexible thin-film probe technology.  Images were taken at different time periods: 2-weeks (left), 4-weeks (middle) and 3-months post implantation (right). Tissue slices are labeled with magenta to highlight microglia (a type of brain cell), and mesh electronics and are colored blue

The researcher believe that there isn't actually an immune response, and that the response they saw is due to damage that occurs when inserting the needle into the brain, and this damage heals over time instead of worsening, which is what happens with conventional probes. 

This minimal response supports the possibility that the mesh system could be implanted permanently. 

'According to our past and ongoing studies thus far, mesh probes can maintain a stable recording/stimulation interface with the brain tissue for at least one to two years,' Dr Lieber says.

Micro computed tomography (3D x-ray) images of two different mesh electronics implanted into a mouse brain in an acute manner. The blue dashed lines represent diameter measurements of each mesh at 10 randomly selected positions, with mesh B being larger 

'However, this time period does not represent the achievable life expectancy since ongoing studies are currently under way to demonstrate even longer-term stability.' 

Due to the limitation of the two- to three-year lifetime of rats, the researchers expect to find more extensive stability in longer-living mammals such as rhesus macaques and in studies currently under way. 

Dr Lieber says that his team is conducting studies of new mesh designs having high numbers of electrodes and multisite injections.

ELON MUSK'S NEURALINK

Elon Musk's latest company Neuralink is working to link the human brain with a machine interface by creating micron-sized devices. 

Neuralink was registered in California as a 'medical research' company last July, and he plans on funding the company mostly by himself. 

It will work on what Musk calls the 'neural lace' technology, implanting tiny brain electrodes that may one day upload and download thoughts. 

In The Matrix, users plugged into a computer using a bulky cable attached to the brain

He said 'neural laces' will help people with severe brain injuries in just four years.  

And in eight to ten years, the Matrix-style technology will be available to everyone, he added.

Neuralink is aiming to launch a product that will help people who suffer from serious brain injuries as a result of disorders such as stroke and cancer in just four years, Musk said. 

'Moreover, our next steps include implantations of mesh electronics into tissues and organs other than the brainâ€"for example, in the eye for recording of single retinal ganglion cells, in the spinal cord, in the muscle for studying signal propagation at the neuromuscular junction, and so on,' said Dr Lieber.

'We're als o beginning studies exploiting the unprecedented stability and absence of chronic immune response of the mesh electronics in Alzheimer's and Parkinson's disease models, and are working on implantation of mesh electronics in non-human primates subjects and human patients.'

Dr Charles Lieber, the co-author of the research, says that 'the mesh electronics should provide unique opportunities for brain-machine interfaces for tetraplegic patients, deep brain stimulations for the treatment of Parkinson's disease, and neural prosthetics in general'

Dr Lieber says that most areas of neuroscience research could benefit from the technology's long-term stability and ability to record signals at the level of a single neuron.

'In addition, almost any clinical/medical application that involves electrical recordings and/or stimulations will benefit from our studies,' said Dr Lieber. 

Dr Lieber also says that 'the mesh electronics should provide unique opportunities for brain-machine interfaces for tetraplegic patients, deep brain stimulations for the treatment of Parkinson's disease, and neural prosthetics in general.' 

 

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