Wednesday, July 18, 2012

How many newly born neurons?  

How many newly born neurons do you see in the image to the left? They are the brown, granular ones.

The image data is from an experiment originally conducted with adult male Sprague-Dawley rats by Elizabeth Gould at Princeton University. The goal of the research was to examine the effects of exercise and social living conditions on adult neurogenesis in rats.

The rats were housed in four groups, corresponding to two experimental variables that each had two conditions:

  1. Living alone or in groups; and
  2. Having access to a running wheel or not having access to a running wheel.
During the experiment, the rats were injected with a dye (bromodeoxyuridine or BrdU) that helps scientists identify neurons that have recently replicated. 

The experiment was run for 12 days, after which the rats were transcardially perfused and their brains were removed. The hippocampus of each rat was sliced very thin (40 μm thick) on a machine called a Vibratome, mounted on slides, and magnified 1,000 X.

The image featured in this blog post is from a rat that was housed with two other rats and had access to a running wheel. According to the scientists, eight newly born neurons are evident in the image (see the key above).

These images are from Science Approach's New Neurons for You After All, in which students learn the neuroscience methods and laboratory techniques by replicating Dr. Gould's research. In the e-lab, students count newly born neurons in hippocampal sections from four rats (36 images in all). Each of the four rats was exposed to one of the four experimental conditions. Students count neurons "in the blind," meaning that they do not know which experimental group a particular rat was assigned to.

After making counts from the 36 images, students add their data to an expert data set, graph the data, and interpret and discuss the results. Support built into the e-lab helps students conduct the neuroimaging portion of the research, write up the results, and think through the hypotheses Dr. Gould tested. 

To learn more about New Neurons for You After All, visit the Science Approach website and purchase the e-lab free with the coupon code provided on the site.

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