PORTLAND, Ore. -- Billions of tiny transmissions take place between the cells of our brains every day. This happens whenever nerve cells reach out toward each other and connect by forming structures called synapses. At these synapses, packets of information sent by one cell are received by other cells. Researchers at Oregon Health Sciences University's Vollum Institute report they have successfully captured on videotape how individual nerve cells send messages. The research is printed in the Aug. 24 edition of the journal Nature.
"This information will help us in understanding synapses," said Wolfhard Almers, Ph.D., a senior scientist at OHSU's Vollum Institute and principal investigator in the study. "Nearly all neurological and mental diseases ultimately involve the failure or malfunction of synapses. Understanding synapses will aid us in discovering treatment strategies."
The messages are sent in the form of vesicles, which are tiny membranous bags filled with a chemical substance called transmitter. When vesicles empty their transmitter onto cells, ion channels open and cause electrical changes, the basis of neural communication. The release of transmitter occurs through a process called exocytosis.
"Synapses allow cells to talk and listen to one another. What we have witnessed and videotaped is the talking portion of this minute conversation," said Almers.
In addition to exocytosis, Almers' lab was able to observe how spent vesicles are replaced when new vesicles attach to the cell membrane. Researchers also tracked the amount of time each vesicle stayed attached before it could release transmitter as part of a communication.
To conduct this research, scientists at the Vollum Institute used a specially redesigned fluorescence microscope to study retinal neurons in goldfish. The microscope allowed researchers to focus on the surface of the cells, imaging life in a superficial layer, a mere 100 nanometers thin. Researchers used this technology to observe cells as vesicles surfaced, bonded with the cell membrane and were later released.
The research was funded by the National Institute of Mental Health (NIMH), a component of the National Institutes of Health. "This work provides a framework for understanding the timing of the molecular machine operating in synapses," says Chiiko Asanuma, Ph.D., chief of signal transduction in the Division of Neuroscience at NIMH. "It's important not only for understanding how the brain works, but for opening up new areas of potential therapies for many brain disorders."
Journal
Nature