Monday, November 12, 2012
Behaviors in Elevated Plus Mazes
We'd noted that Rats and Mice are observed to behave quite differently when put in the same elevated plus maze. Our rodent guru tells us that while superficially similar norway rats and lab mice, Rattus rattus, and Mus musculus are not even generically similar. Even at quite a coarse scale, norway rats have 22 chromosome pairs, lab mice have 20 (Levan 1991) and the common ancestor is at least 8 million years ago - as far back as humans are separated from Great Apes. The Rat Genome Sequencing Consortium 2004 tells us that Norway rats have 2.75 million base pairs while mice have 2.6 million so we'd expect significant differences.
I'd noted that with the HVS Image 2012 series Elevated Plus Maze the physical mazes are actually provided in different sizes for the two animals - for example the width is 50mm in the HVS Image Mouse Maze and 100mm in the HVS Image Rat maze so it's possible that its just a question of scaling.