| Stanford scientists have developed a system for observing real-time brain activity in a live mouse. The device could prove useful in studying new treatments for neurodegenerative diseases, such as Alzheimer's. |
Along with related research using zebrafish, these developments in neuroscience may eventually lead to technologies that would enable our brains to be uploaded. At the very least the techniques could have substantial bearing on the upcoming Brain Activity Map project.
The scientists planted tiny probes inside the brains of mice to detect what were essentially mouse memories, according to a study published last month in the online edition of Nature Neuroscience.
The experiment involved the insertion of a needlelike microscope into the hippocampus - a part of the brain associated with spatial and episodic memory. The microscope detected cellular activity and broadcast digital images through a cell phone camera sensor that fit like a hat over the heads of the critters as they scampered around an enclosure.
"We're not really reading their minds," said the lead researcher, Mark Schnitzer, who is an associate professor of biology and applied physics at Stanford. "What is the mind of a mouse, anyway? I don't know. What we're doing is reading a spatial map in the brain. It is one little component of many, many processes that are going on inside."
Over the course of a month, the scientists were able to document patterns of activity in some 700 neurons and pinpoint areas of the brain where mice store long-term information. It is important, Schnitzer said, because long-term memory is an area of the brain that researchers are struggling to understand as they attempt to develop new therapies for neurodegenerative diseases, including Alzheimer's disease.
"Those are clearly diseases in which information storage has been impaired," Schnitzer said. "Now that we can look at the neural code for how the spatial information is stored, it opens the door directly to subsequent experiments. That's the logical next step."
The neural implant captures the light of roughly 700 neurons. The microscope is connected to a camera chip, which sends a digital version of the image to a computer screen
The computer then displays near real-time video of the mouse's brain activity as a mouse runs around a small enclosure, which the researchers call an arena.
The neuronal firings look like tiny green fireworks, randomly bursting against a black background, but the scientists have deciphered clear patterns in the chaos.
"We can literally figure out where the mouse is in the arena by looking at these lights," said Mark Schnitzer, an associate professor of biology and of applied physics and the senior author on the paper, recently published in the journal Nature Neuroscience.
When a mouse is scratching at the wall in a certain area of the arena, a specific neuron will fire and flash green. When the mouse scampers to a different area, the light from the first neuron fades and a new cell sparks up.
"The hippocampus is very sensitive to where the animal is in its environment, and different cells respond to different parts of the arena," Schnitzer said. "Imagine walking around your office. Some of the neurons in your hippocampus light up when you're near your desk, and others fire when you're near your chair. This is how your brain makes a representative map of a space."
The group has found that a mouse's neurons fire in the same patterns even when a month has passed between experiments. "The ability to come back and observe the same cells is very important for studying progressive brain diseases," Schnitzer said.
For example, if a particular neuron in a test mouse stops functioning, as a result of normal neuronal death or a neurodegenerative disease, researchers could apply an experimental therapeutic agent and then expose the mouse to the same stimuli to see if the neuron's function returns.
Although the technology can't be used on humans, mouse models are a common starting point for new therapies for human neurodegenerative diseases, and Schnitzer believes the system could be a very useful tool in evaluating pre-clinical research.
The invention is still a long way from being used on humans, but it may soon be available to other experimenters. Three students who worked on the project have formed a startup company called Inscopix Inc., and they plan to sell the technology to neuroscience researchers.
SOURCE Stanford University
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