Researchers Develop Flexible Tentacle Electrodes to Record Brain Activity

Researchers at ETH Zurich have developed new ultra-flexible brain probes that can accurately record brain activity without causing tissue damage, opening up new avenues for the treatment of a range of neurological and neuropsychiatric disorders. 
 
According to Mehmet Fatih Yanik, Professor of Neurotechnology at ETH Zurich, further research on Neurostimulators will greatly expand their potential applications. Currently, Neurostimulators, also known as brain pacemakers, send electrical impulses to specific areas of the brain via special electrodes.
 
Instead of using Neurostimulators exclusively to stimulate the brain, the electrodes can also be used to precisely record brain activity and analyze it for anomalies associated with neurological or psychiatric disorders. In a second step, it would be conceivable to treat these anomalies and disorders using electrical impulses.
 
Yanik and his team have developed a new type of electrode that enables more detailed and more precise recordings of brain activity over an extended period. These electrodes are made of bundles of extremely fine and flexible fibers of electrically conductive gold encapsulated in a polymer. These bundles can be inserted into the brain very slowly, which is why they do not cause any detectable damage to brain tissue.
 
“The wider the probe, even if it is flexible, the greater the risk of damage to brain tissue,” Yanik explained. “Our electrodes are so fine that they can be threaded past the long processes that extend from the nerve cells in the brain. They are only around as thick as the nerve-cell processes themselves.”
 
The research team tested the new electrodes on the brains of rats using four bundles, each made up of 64 fibers. In principle, as Yanik explains, up to several hundred electrode fibers could be used to investigate the activity of an even greater number of brain cells. In the study, the electrodes were connected to a small recording device attached to the head of each rat, enabling them to move freely.
 
In the experiments, the research team was able to confirm that the probes are biocompatible and that they do not influence brain function. The electrodes’ closeness to the never cells caused stronger signal quality than other methods. The bundles could also branch out in different directions, meaning that they can reach multiple brain areas.
 
In the study, researchers used the new electrodes to track and analyze nerve-cell activity in various areas of the brains of rats over several months. Signals were recorded from the same cells in the brains of animals for the entire duration of a ten-month experiment. Examinations showed that no brain tissue damage occurred during this time.
 
 
Researchers also determined that nerve cells in different regions were “co-activated”. Scientists believe that this large-scale, synchronous interaction of brain cells plays a key role in the processing of complex information and memory formation.
 
The group has teamed up with researchers at the University College London to test the diagnostic use of the new electrodes in the human brain. The project involves epilepsy sufferers who do not respond to drug therapy. In such cases, neurosurgeons may remove a small part of the brain where the seizures originate. The idea is to use the group’s method to precisely localize the affected area of the brain before tissue removal.
 
Using the new electrodes, it might be possible to detect the pathological signals generated by the neural networks in the brain in advance, and then stimulate the brain in a way that would alleviate such disorders. Yanik also believes that this technology may result in brain-machine interfaces for people with brain injuries.