For nearly nine years, researchers have been working on developing implantable electrodes that can capture signals from single neurons in the brain over a long period of time - without causing brain tissue damage. They are now one big step closer to reaching this goal, and the results are published in the journal Frontiers in Neuroscience. The technology would make it possible to understand brain function in both healthy and diseased individuals.
The researchers' tailored electrodes, which they call 3-D electrodes, are unique in that they are extremely soft and flexible in all three dimensions, in a way that enables stable recordings from the neurons over a long time.
The electrode is so soft that it deflects against a water surface. In order to implant such electrodes, the researchers have developed a technique for encapsulating the electrodes in a hard but dissolvable gelatine material that is also very gentle on the brain.
Until now, developed flexible electrodes have not been able to maintain their shape when implanted, which is why they have been fixated on a solid chip that limits their flexibility, among other things. Other types of electrodes that are used are much stiffer. The result in both cases is that they rub against and irritate the brain tissue, and the nerve cells around the electrodes die.
"The signals then become misleading or completely non-existent. Our new technology enables us to implant as flexible electrodes as we want, and retain the exact shape of the electrode within the brain", the researchers said.
"This creates entirely new conditions for our understanding of what happens inside the brain and for the development of more effective treatments for diseases such as Parkinson's disease and chronic pain conditions than can be achieved using today's techniques", they concluded.
Facts about the electrodes
The electrodes are made of 4 μmgold leads and individually insulated with 4 μm parylene. The array of electrodes consists of eight flexible channels, designed to follow the movement of the brain.
Both the electrode and implantation technology, which have been tested on rats, are patented by NRC researchers, in Europe and the US, among other places.