The new method of Real-Time Tracking of Serotonin/Dopamine

According to foreign media New Atlas, dopamine and serotonin are brain chemicals related to a series of neurological diseases such as Parkinson's disease and depression, so understanding how they work may be the key to developing more effective treatments for these diseases. A new tool provides an unprecedented opportunity to observe the effects of these neurotransmitters, enabling scientists to monitor their real-time activity for the first time.

For a long time, both dopamine and serotonin are related to the brain's ability to process rewards, but recently scientists have turned their attention to how they play a broader role in the entire human body. This includes how serotonin in the intestine regulates blood sugar or how ketamine solves the problem of low levels, and how deep brain stimulation (DBS) promotes dopamine production in Parkinson's disease patients. The last example is a particularly promising example, because Parkinson’s disease is characterized by the depletion of dopamine production in the brain, which leads to loss of control of body movements. Using DBS, that is, implanting tiny wires in the patient's body to deliver electrical current to specific areas of the brain, is a way to solve symptoms such as tremor and slow movement, as well as dopamine deficiency.

Five patients were arranged to receive DBS treatment at Wake Forest Baptist Medical Center. Two of them suffered from Parkinson's disease and three suffered from essential tremor, which is an involuntary movement disorder of the nervous system. When neurosurgeons implanted their electrode arrays to provide DBS treatment, another team, including scientists from Virginia Tech, worked with them to insert their own carbon fiber microelectrodes deep into the brain with the purpose of detecting and recording neurons Serotonin and dopamine released.

With the patients still awake, the researchers asked them to practice some decision-making. They had to decide which direction to move on the screen after a series of small dots disappeared. Each patient performed 200 to 300 tasks and was asked from time to time to show how confident they were in their answers. At the same time, a low voltage is applied to the electrode to detect the activity of dopamine and serotonin in real time. Scientists call this electrochemical method fast-scanning cyclic voltammetry, which enables them to record sub-second fluctuations in dopamine and serotonin signals for the first time in history.

"A large number of people around the world are taking pharmaceutical compounds to disrupt the dopamine and serotonin emitter systems to change their behavior and mental health," said P. Read Montague of Virginia Tech, the senior author of the study. "For the first time, we measured the time-to-moment activities in these systems, and determined their participation in perception and cognition. These neurotransmitters work at the same time and integrate activities on completely different time and space scales, which is more than anyone expected Everything is good."

The team said this is a huge improvement over previous efforts to track these neurotransmitters, because these neurotransmitters cannot provide the same frequency and number of measurements. Scientists can draw some useful insights from their experiments. They found that when subjects were more uncertain about their answers, serotonin levels increased, and when they were more certain, serotonin levels decreased. When the subject is expected to make a decision, dopamine seems to increase, while the serotonin level decreases. When the two reach a certain level, the final choice is made.

"This study reveals the role of these neurochemicals in learning, brain plasticity and how we perceive the environment," said lead researcher Kenneth T. Kishida. "We now understand in more detail how our brain constructs what we perceive, uses these perceptions to make decisions, and explains the consequences of the choices we make. Dopamine and serotonin seem to be crucial in all of these processes. Importantly, such research will help us and other scientists better understand how drugs or drugs like serotonin reuptake inhibitors affect cognition, decision-making, and mental illnesses such as depression."

The research was published in the journal Neuron.