Electroencephalogram will be registered by stentrodes
Stent electrodes will allow you to read signals through the circulatory system of the brain
DailyTechInfo based on IEEE Spectrum: Stent Electrode Reads Brain Signals From Inside a Vein
Brain-computer interfaces, which have been developed in sufficient numbers in recent years, allow paralyzed people to control the "power of thought" with specialized robotic prostheses, exoskeletons, robots and computer program user interface controls. In most cases, such interfaces require electrodes or chips surgically implanted into the brain, which provide a minimum level of noise and interference relative to the level of the useful signal from neurons. However, a new type of electrode, which is similar in design to a medical stent, can provide high-quality recording of neuronal signals without the need for dangerous surgical operations on the open brain. The "stentrode" electrode, the size of a match, which was developed by a group of Australian scientists, can simply be inserted into a vein that is part of the circulatory system of the brain.
Such an electrode-stent is introduced into the body through a catheter inserted into a vein in the neck of a person. This device receives electrical signals and transmits them through the thinnest wire to the receiver, which is embedded under the skin in the area of the pectoral muscle. This receiver is also a transmitter that transmits all received signals using wireless information transmission technologies. The final recipient of this information may be prosthetic control systems, exoskeletons or other electronic devices.
Testing the developed technology, the scientists recorded high-quality signals from neurons. Stent electrodes were inserted into the circulatory system of an experimental animal, a sheep, which was not limited in its mobility. Six months of taking brain signals allowed scientists to accumulate a sufficient amount of data, perform a spectral analysis of the signals and calculate the value of the bandwidth. All these qualitative indicators of signals almost completely correspond to the indicators of signals received from electrode arrays surgically implanted in the brain.
The electrode-stent is made of nitinol, a biologically neutral alloy of nickel and titanium. It is a "tube" with a diameter of 3 millimeters and a length of 3 centimeters, having a soft lattice surface on which tiny disk-shaped electrodes are fixed. Placed inside a vein, such an electrode takes the form of a vein and does not interfere with the blood circulation process at all. The signal bandwidth of such an electrode is sufficient to ensure the removal of electrical signals from 10 thousand individual neurons.
"During the first few days after the introduction, the electrode stand gave an extremely unstable signal, which is explained by the interference in its operation of noises created by the flow of blood," says Thomas Oxley, a neurologist at the University of Melbourne, "But after six days in the vein, the electrode began to give out stronger and more clear signals. The performed X-ray showed that the outer shell of the electrode simply grew into the walls of the blood vessel, which became protection from external noise. And the complete absence of rejection processes demonstrates the high biological compatibility of the device."
The stentrode electrode allows recording signals with a frequency of up to 190 Hertz. "These high-frequency signals, ranging from 70 to 200 Hz, are the most informative, they contain a lot of information from the motor cortex of the brain and these signals are the most useful type of signals for implementing direct brain-computer interfaces," says Thomas Oxley.
So far, Australian researchers have not made any attempts to decipher the signals received with the help of stent electrodes. This will require at least the introduction of these electrodes into a more highly developed animal, for example, a monkey. "However, the veins of laboratory monkeys, rhesus monkeys, are very thin for the introduction of a stent into them. We plan to start immediately with the introduction of these electrodes into the veins of a human volunteer and after that it will be possible to start trying to decipher the signals taken from his brain," says Thomas Oxley. Testing of electrodes on volunteers is scheduled to begin at the end of 2017, and a group of paralyzed patients undergoing treatment at the Royal Melbourne Hospital, Australia, will act as volunteers.
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18.02.2015