Silent Synapses
Not all dopaminergic synapses are activated when stimulated – what can they teach us about neurotransmission?
A new optical technique allows scientists to watch neurotransmission in more detail than ever before. One of the most intriguing findings is the presence of functionally silent dopamine vesicle clusters (1). “We suspected that there must be a wide variety of different synaptic properties, even between synapses on the same axon,” says David Sulzer, co-lead researcher, and Professor of Neurobiology in Psychiatry-Neuroscience and Pharmacology at Columbia University Medical Center, “But we did not have the means to observe individual synapses.”
The researchers developed fluorescence false neurotransmitter 200 (FFN200), which mimics the action of natural neurotransmitters in neuronal cell culture and brain tissue. By monitoring FFN200 with the Ca2+ influx during exocytosis, they found that only a small fraction of axonal terminals released dopamine – which they further confirmed by using an endocytic probe. The function of these silent synapses is unknown, but the crucial role of dopamine in learning, decision making, and motor function, suggests a range of possibilities.
“We don’t yet know what makes some synapses silent and others active, but it could suggest new ways in which they become selected to produce new memory and learning,” says Sulzer.
In an effort to discover the source and cause of silent synapses, the research team plan to investigate the disparities between synapses in diseased and healthy brain function, as well as studying these traits while animals are learning, and during certain behaviors.
- DB Pereira et al., “Fluorescent false neurotransmitter reveals functionally silent dopamine vesicle clusters in the striatum”, Nat Neurosci, 19, 578–586 (2016).
My fascination with science, gaming, and writing led to my studying biology at university, while simultaneously working as an online games journalist. After university, I travelled across Europe, working on a novel and developing a game, before finding my way to Texere. As Associate Editor, I’m evolving my loves of science and writing, while continuing to pursue my passion for gaming and creative writing in a personal capacity.