Getting In Touch With The Brain

Scientists are inventing new ways of direct contact with brain impulses and metabolic activity.  At the University of Washington, a team of neuroscientists used surface electrodes to allow human patients to move a cursor on a computer screen using only their thoughts.

Neuroscientists at UCLA have developed a chemical sensor electrode for implantation alongside deep brain stimulation (DBS) electrodes.  These sensors will track dopamine and serotonin concentrations as they change in response to the DBS.

During the conventional deep brain stimulation procedure, neurosurgeons insert a small electrode into the brain. The patient is awake during the surgery so that the surgeon can find the optimal location and level of stimulation to reduce the patient's symptoms. In Parkinson's patients, for example, muscle tremors are often immediately and visibly reduced with the appropriate stimulation.

However, the actual mechanisms behind its therapeutic effect are hotly debated. Recording the release of the brain's signaling chemicals, known as neurotransmitters, could help to resolve the question, allowing neurosurgeons to better optimize the procedure.

The device consists of a custom-designed sensor electrode that is implanted along with the stimulating electrode, a microprocessor, a Bluetooth module to send data to a computer, and a battery. "It allows us to record dopamine and serotonin wirelessly in real time," says Kendall Lee, a neurosurgeon at the Mayo Clinic, Rochester, MN, who helped develop the device. "That means we have tremendous control over the chemistry of the brain."

To detect neurotransmitters, researchers apply a low voltage across the electrode. That oxidizes dopamine molecules near the electrode, triggering current flow at the electrode. "The amount of current flow gives a relative indication of concentration," says Kevin Bennet, chairman of the division of engineering at the Mayo Clinic and one of Lee's collaborators.

Preliminary research in pigs using the new system has shown that deep brain stimulation of the area targeted in Parkinson's patients triggers release of dopamine. Researchers now aim to repeat these experiments in pigs that have some of the symptoms of the disease. For example, the sensors could detect whether certain patterns of dopamine correspond to improvements or worsening of Parkinson's symptoms. _TechReview

Yes, these are baby steps. Understanding what is happening in the brain in response to artificial DBS will be helpful. But what we really need is to understand what is happening at all levels (electromagnetic, physiological, biochemical, genetic, etc) during everyday brain activity.

Nano-implants that provide real time monitoring of multi-channel brain activity plus providing a wireless means of mentally controlling prostheses plus providing a channel for DBS etc. will be available in the next 10 to 20 years.