Having a chip in your brain still sounds like science fiction. But for many Parkinson patients, now it is more than just “magic therapy”. And some recent developments are opening up entirely new and fascinating applications.
What do electronics and our brains have in common? Both use electric impulses to process information. So having a chip among the estimated 100 billion nerve cells doesn’t sound as unusual as it did before. And for thousands of Parkinson’s patients, it has been their last hope for decades.
Neurosurgeons first placed tiny electrodes just a few square millimeters in size into an overly active portion of the brain some 30 years ago. Linked to a battery via wires beneath the skin, they have been using weak currents with impulse frequencies between 100 and 200 hertz to inhibit activity in that region of the brain, which reduces the movement disorder. More than 60,000 Parkinson’s patients around the world have this type of “brain pacemaker”.
Twenty-five years later, a method known as deep brain stimulation (DBS) is waiting to also be approved for severe depression. Generally speaking, the list of diseases that could be treated directly in the brain someday is getting longer and longer. It includes chronic headache, epilepsie and, more recently, obsessive-compulsive and anxiety disorders and addictive behavior. In the EU, systems of this type have been approved for epilepsy since 2010.
Similar to artificial intelligence, actual practice has proved that the method works. Although nobody is certain exactly how it works. Explanations range from inhibiting activity in the stimulated region of the brain to stimulating downstream centers.
Brain implants as an early warning system
Still, stimulation is only one aspect of neurochips. They also work in the other direction. For patients with epilepcy, they are a type of early-warning system because they register brain waves and send out a warning when they notice typical abnormalities.
The very idea of measuring one’s “thoughts” is far more stimulating to the imagination than treating the brain with electric impulses. Years ago, scientists at Washington University used brain implants to control a computer cursor by recording electrical activity diverted from the cerebral cortex. The human “guinee pig” had to think of certain vowels to make it move.
Last year, the first quadraplegic “thought controller” was able to move his hand again thanks to a mini computer chip in the responsible portion of the brain and an under-arm cuff with 130 electrodes. Scientists at Ohio State University also developed adaptive software that decodes characteristic patters of brain activities and then sends them to the arm.
A neuro chip developed at the École Polytechnique Fédérale in Lausanne performed a similar function. It recorded movement impulses in a monkey’s brain and transmitted them to a computer. The computer compiled a simulation protocol for a impulse generator Taktgeber that moves the primate’s leg muscles via 16 electrodes.
Still, these “mind readers” are hardly suitable for daily use. For that, they would have to be smaller and wireless. It would also be necessray to keep them “running” in the body for longer periods of time. However, after a while, the immune system identifies them as foreign objects. That limits their ability to function so much that they would hardly be able to process signals after just a few weeks.
Now, a new microprobe with medicine-coated electrodes might remedy the situation. It grows into the nerve tissue without causing inflammation and produces full-strength signals even after twelve weeks. The polymer PEDOT stores the anti-inflammatory medication Dexamethasone and releases it when voltage is applied. It releases the medication directly around the implant, regulates the dosage and controls the exact time it is administered.
Researchers at the BrainLinks-BrainTools Excellence Cluster, the Institute for Microsystem Technology (IMTEK) and Universitätsklinikum Freiburg feel that the new generation of brain implants is a promising approach for longterm treatment of patients.