Only a small portion of synapses may be active during neurotransmission
News Feb 27, 2016
New optical technique, used in mice, offers detailed look at how dopamine works in the brain -
Columbia University scientists have developed a new optical technique to study how information is transmitted in the brains of mice. Using this method, they found that only a small portion of synapses may be active at any given time.
The study is published in Nature Neuroscience.
“Understanding how we accomplish complex tasks, such as learning and memory, requires us to look at how our brains transmit key signals across synapses from one neuron to another,” said David Sulzer, PhD, professor of neurobiology in Psychiatry, Neurology, and Pharmacology at Columbia University Medical Center. “Older techniques only revealed what was going on in large groups of synapses. We needed a way to observe the neurotransmitter activity of individual synapses, to help us better understand their intricate behavior.”
To obtain a detailed view of synaptic activity, Sulzer’s team collaborated with the laboratory of Dalibor Sames, PhD, associate professor of chemistry at Columbia, to develop a novel compound called fluorescent false neurotransmitter 200 (FFN200). When added to brain tissue or nerve cells from mice, FFN200 mimics the brain’s natural neurotransmitters and allows researchers to spy on chemical messaging in action.
The FFN200 fluorescent molecule tracking neurotransmission of dopamine in mouse synapses. Credit: Sulzer lab, Columbia University Medical Center
Using a fluorescence microscope, the researchers were able to view the release and reuptake of dopamine—involved in motor learning, habit formation, and reward-seeking behavior—in individual synapses. When all the neurons were electrically stimulated in a sample of brain tissue, the researchers expected all the synapses to release dopamine. Instead, they found that less than 20 percent of dopaminergic synapses were active following a pulse of electricity.
“Why are there these large reservoirs of synapses that are silent?” said Dr. Sames, a co-author of the paper. “Perhaps these silent terminals hint at a mechanism of information coding in the brain that’s yet to be revealed.”
The study’s authors plan to pursue this hypothesis in future experiments, as well as examine how other neurotransmitters behave.
“This particular study didn’t explain what’s causing most of the synapses to remain silent,” said Dr. Sulzer. “If we can work this out, we may learn a lot more about how alterations in dopamine levels are involved in brain disorders such as Parkinson’s disease, addiction, and schizophrenia.”
Note: Material may have been edited for length and content. For further information, please contact the cited source.
Pereira DB et al. Fluorescent false neurotransmitter reveals functionally silent dopamine vesicle clusters in the striatum. Nature Neuroscience, Published Online February 22 2016. doi: 10.1038/nn.4252
Synaptotagmin 7 Ensures Efficiency of Inhibitory Signal TransmissionNews
Researchers at IST Austria define function of an enigmatic synaptic protein, synaptotagmin 7.READ MORE
Molecules in Spit Could Help Diagnose ConcussionsNews
Diagnosing a concussion can sometimes be a guessing game, but clues taken from small molecules in saliva may be able to help diagnose and predict the duration of concussions in children, according to Penn State College of Medicine researchers.READ MORE
Elpis BioMed Closes Funding Round to Commercialise Novel Technology Platform for Generating Human Cell TypesNews
New Cambridge spin-out company commercialises disruptive technology that enables rapid generation of pure and consistent batches of human cell types. Geographically diversified, top-tier investor team includes key industry leaders to support early company development.READ MORE