Max Planck and a mouse whisker

Mice at Max Planck Institute get a shave, save for one whisker.

And then scientist watch what the mouse does with that one whisker.

Marcel Oberlander

“We have these two little platforms with a gap between them, and we see how long it takes for the mouse to jump the gap. To figure it out, it uses its whiskers as it’s primary sense, like we use our fingertips,” explained researcher Marcel Oberlander. “We increase the gap. It fails. It returns. We do this at a certain age after its birth and see what changes.”

Each whisker is controlled by a well-defined region in the brain, he said.

“In the brain of a rodent, there are function units, with a couple of thousands of neurons that process the information coming from the whiskers,” said researcher Hanno Meyer. “Thus, you have a system of 10,000 neurons, and we are looking at how (the system) is built and organized.

“Once we know how the neurons work, then we are able to analyze what goes on when it is diseased.”

Only one whisker

How can a one-whiskered mouse be compared to a human? “A mouse has a cortex,” Meyer said. “It can learn. It can exhibit disturbed behavior. It can solve tasks. Jumping the gap is kind of like giving a human a little pinch, and gives us some idea of how the brain works.”

Obviously, mapping out all those neurons in the mouse’s brain is going to be a bit time consuming.

“There are billions of neurons, each with 5,000 connections, and we want to find all those connections. That’s quite a process,” Oberlander said.

To help them do this, the scientists use a machine called the microtome, which slices a mouse’s brain into several hundred slices. Then, the slices are stained and put under a confocal microscope where high resolution scans are made of several hundred tiles of that slice. Then the tiles are stitched together using special software, so that a whole picture of the slice can be made and all the neurons identified and analyzed.

Then, they will scan the brain of a mouse afflicted with Alzheimer’s and note the differences.

The researchers also make living brain records of the activity of the neuron, using the patch clamp technique.

(They work with Dr. Bert Sakmann, the 1991 Nobel Laureate in Medicine and inaugural scientific director of the Max Planck Florida Institute. With German physicist Erwin Neher, Sakmann used the patch-clamp technique to establish the existence of sets of ion channels in cell membranes, some permitting the flow of only positive ions, while others pass only negatively charged ions. Once they established that, they examined a range of cellular functions, eventually discovering the role that ion channels play in a variety of diseases.)

Meyer explains how to make those records: “You take a glass pipette with a single opening and put it on an electrode, which is advanced into the brain and records the activity on a graph that will show the firing spikes of a single neuron. When it fires a spike all the neurons to it are either inhibited or excited.”

The purpose of this research is to provide scientists with a clear picture of a healthy, functioning brain, so that they can understand degenerative neurological diseases like Alzheimer’s.

written for Palm2Jupiter

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