April 29, 2008, Houston, TX--A new technique that combines an ultrafast laser beam with a special microscope to look at tissues in different optical planes will enable scientists to get a three-dimensional view of neurons or nerve cells as they interact, according to Baylor College of Medicine scientists.
Their technical report on this device appears in the April 27 issue of Nature Neuroscience.
"Most microscopes can only study cell function in two dimensions," said Dr. Gaddum Duemani Reddy, an M.D./Ph.D. student at BCM and Rice University and also first author of the study. "To look at different planes, you have to move your preparation (of cells) or the objective lens. That takes time, and we are looking at processes that happen in milliseconds."
To solve that problem, he said, they developed an imaging system that utilizes a unique arrangement of acousto-optic deflectors to steer a focused, ultra-fast laser beam to arbitrary locations in three-dimensional space without moving the objective lens. According to Reddy, this highly versatile random-access multiphoton microscope supports functional imaging of complex three-dimensional cellular structures such as neuronal dendrites or neural populations at acquisition rates on the order of tens of kilohertz.
"We are starting to see how a single neuron behaves in our laboratory," he said. The next step, he said, will be to use to it to look at clusters or colonies of neurons. This will enable them to actually see the neuronal interactions.
"At present, the technology is applied in my lab to study information processing of single neurons in brain slice preparations by 3D multi-site optical recording," said Dr. Peter Saggau, professor of neuroscience at BCM and the paper's senior author.
He is collaborating with two other labs on using the technology in other ways. In one, he said, researchers plan to use the technology to monitor nerve activity in the brains of lab animals in order to study how populations of neurons communicate during visual stimulation. Another study attempts to use the technology to monitor stimulation of the acoustic nerve optically. Those scientists hope to reinstate hearing in lab animals whose inner ear receptors do not work.
Others who took part in the research include Keith Kelleher of the University of Houston and Rudy Fink of BCM.
Funding for this work comes from the National Institutes of Health and the National Science Foundation.
The full article can be found at www.nature.com/neuro/index.html.