In a scientific first that potentially could shed new light on how signals travel in the brain, how learning alters neural pathways, and might lead to speedier drug development, scientists at Harvard have created genetically-altered neurons that light up as they fire.
The work, led by John L. Loeb Associate Professor of the Natural Sciences Adam Cohen, and described in Nature Methods on Nov. 28, involved using a gene from a Dead Sea microorganism to produce a protein that, when exposed to the electrical signal in a neuron, fluoresces, allowing researchers to trace the propagation of signals through the cell.
"It's very exciting," Cohen said of the research. "In terms of basic biology, there are a number of things we can now do which we've never been able to do. We can see how these signals spread through the neuronal network. We can study the speed at which the signal spreads, and if it changes as the cells undergo changes. We may someday even be able to study how these signals move in living animals."
To create the light-up neurons, Cohen and his team infected brain cells that had been cultured in the lab with a genetically-altered virus that contained the protein-producing gene. Once infected, the cells began manufacturing the protein, allowing them to light up.
"The way a neuron works is it has a membrane around the whole cell, sort of like a wire and insulation, except in a neuron the membrane is an active substance," Cohen said. "Normally, the inside of the cell is negatively-charged relative to the outside.
"When a neuron fires, the voltage reverses for a very short time, about 1/1,000th of a second," he continued. "This brief spike in voltage travels down the neuron and then activates other neurons downstream. Our protein is sitting in the membrane of the neurons, so as that pulse washes over the proteins, they light up, giving us an image of the neurons as they fire."
The research has the p
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