Powerful new scientific tools are emerging that could allow scientists to better understand the human brain by studying the relatively simpler brains of mice. These methods allow scientists to alter genes, the instructions in DNA that control the behavior of cells - including the neurons that form brain circuits. By using genetic methods for mapping brain connections and controlling the activity of cells, scientists hope to generate detailed wiring diagrams of the brain and probe how these circuits function.
"While mice can not replace the work that is being done in monkeys, these research techniques are much further along in mice than in monkeys," Callaway says. "The ability to modify neural activity using genetic tools and to study the resulting changes in brain and nerve activity is revolutionizing neuroscience."
Although such genetic engineering techniques in mice offer huge potential, little was known about what areas of the mouse visual cortex - the high-level brain region that computes the meaning of signals from the eyes - were responsible for processing different elements of the visual information.
To remedy this, Callaway and his colleagues set out to chart a map of the mouse's visual processing system. They injected mice with a calcium-sensitive fluorescent dye that glows when exposed to a certain color of light. The amount of calcium in nerve cells varies depending on the activity level of the neurons, so the scientists could measure the activity of brain cells based on how brightly they glowed.
The scientists then displayed different types of visual stimulus on a television monitor and recorded what parts of the brain glowed. To make the recordings, they used a high-resolution camera capable of discerning the activity of individual nerve cells.
They found that a mouse's visual field, the area of three-dimensional spac
|Contact: Andy Hoang|