Tracking real-time chemical changes in brain aids treatment of
15 August 2012
A novel way to monitor
real-time chemical changes in the brains of patients undergoing deep
brain stimulation (DBS) has been developed at Mayo Clinic in the US.
It will help
physicians more effectively use DBS to treat brain disorders such as
Parkinson’s disease, depression and Tourette syndrome.
are published in the journal Mayo Clinic Proceedings. Researchers hope to use the discovery to create a DBS system that
can instantly respond to chemical changes in the brain. Parkinson’s,
Tourette syndrome and depression all involve a surplus or deficiency
of neurochemicals in the brain. The idea is to monitor those
neurochemicals and adjust them to appropriate levels.
learn what neurochemicals can be released by DBS, neurochemical
stimulation, or other stimulation. We can basically learn how the
brain works,” says author Su-Youne Chang, Ph.D., of the Mayo Clinic
Neurosurgery Department. As researchers better understand how the
brain works, they can predict changes, and respond before those
changes disrupt brain functioning.
Observing neurotransmitter changes
Researchers observed the real-time changes of the
neurotransmitter adenosine in the brains of tremor patients
undergoing deep brain stimulation. Neurotransmitters such as
dopamine and serotonin are chemicals that transmit signals from a
neuron to a target cell across a synapse.
The team 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.
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.
Tremors are a visual cue that the technique is working;
researchers suspect adenosine plays a role in reducing tremors.
Researchers also hope to learn more about conditions without such
“We can’t watch pain as we do tremors,” says Kendall Lee, MD,
PhD, a Mayo Clinic neurosurgeon. “What is exciting about this
electrochemical feedback is that we can monitor the brain without
external feedback. So now, we can monitor neurochemicals in the
brain and learn about brain processes like pain.”
DBS has been used successfully worldwide to treat patients with
tremors. However, physicians do not fully understand why DBS works
in patients. They know that when DBS electrodes are inserted before
electrical stimulation, there is an immediate tremor reduction.
Known as the microthalamotomy effect, it is reported in up to 53
percent of patients and known to last as long as a year. Researchers hope to use the study findings to create a
self-contained “smart” DBS system.
“With the stimulator and detection, we can create algorithms and
then raise neurotransmitters to a specified level,” says Kevin
Bennet, a Mayo Clinic engineer who helped create the system. “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.”