Tool Tracks Chemical Changes in the Brain

The research conducted by the Mayo Clinic will help physicians more effectively use DBS to treat brain disorders.

"We can learn what neurochemicals can be released by DBS, neurochemical stimulation, or other stimulation. We can basically learn how the brain works," author Su-Youne Chang, Ph.D., of the Mayo Clinic Neurosurgery Department was quoted saying.

Researchers observed the real-time changes of the neurotransmitter adenosine in the brains of tremor patients undergoing deep brain stimulation. They used fast scan cyclic voltammetry (FSCV) to quantify concentrations of adenosine released in patients during deep brain stimulation. The data was recorded using Wireless Instantaneous Neurotransmitter Concentration Sensing, a small wireless neurochemical sensor implanted in the patient's brain.

The sensor, combined with FSCV, scans for the neurotransmitter and translates that information onto a laptop in the operating room. The sensor has previously identified neurotransmitters serotonin and dopamine in tests in brain tissue. This was the first time researchers used this technique in patients.

"We can't watch pain as we do tremors," Kendall Lee, M.D., Ph.D., a Mayo Clinic neurosurgeon, was quoted saying. "What is exciting about this electrochemical feedback is that we can monitor the brain without external feedback.

DBS has been used successfully worldwide to treat patients with tremors. However, it's not fully understood why DBS works in patients. Doctors do know that when DBS electrodes are inserted before electrical stimulation, there is an immediate tremor reduction, known as the microthalamotomy effect.

"With the stimulator and detection, we can create algorithms and then raise neurotransmitters to a specified level," Kevin Bennet, a Mayo Clinic engineer who helped create the system, was quoted saying. "We can raise these chemicals to appropriate levels, rising and falling with each person throughout their life. Within milliseconds, we can measure, calculate and respond. From the patient's perspective, this would be essentially instantaneous."

They hope to use the discovery to create a DBS system that can instantly respond to chemical changes in the brain.

Source: Mayo Clinic Proceedings, July 2012