Window into Brain Sleep

Sleep builds learning and memory. Many studies show this–and we keep telling students that sleep will improve their grades. But how does it work? Here’s an actual window into a mouse brain, watching what might be new memories form.

At the NYU Skirball Institute (as typed, not “Screwball”) researchers Wen-Biao Gan and colleagues tested a mouse genetically modified to express Yellow Fluorescent Protein (YFP) in its brain neurons. This means that one of the mouse’s own genes in the DNA was fused to a DNA sequence encoding the fluorescent YFP; so the mouse’s own cells make the protein. Now, the researchers cut a window into the mouse’s skull, which enables them to put a microscope up to the brain and record photons coming out of YFP. Thus, one can take live pictures of individual mouse brain neurons as they grow.

How does the experiment work? First, mice are trained to learn a new task, how to climb upon a rotating bar. After learning this challenging task, the mice take a nap. That is, they are allowed to sleep as they wish for 8 hours, or else sleep-deprived for 8 hours. How the mice were sleep-deprived is described as “gentle handling” — not sure what that means. I would think 8 hours of hiphop music and fending off drunk bros would work better.

The bottom line is that:

• After training, the microscope at the brain window detects neurons forming new “dendritic spines,” that is, branches on the nerve dendrites that may form new connections with other neurons–part of learning and stabilizing a new task or memory.
• Mice that get to sleep form  more dendritic spines than mice that are sleep-deprived. Presumably, the well-rested mice learn their tasks better.

Much food for thought when planning your schedule next fall.