-
Having
a bigger brain doesn't necessarily make you smarter. That's the conclusion
of a series of experiments with transgenic mice performed in Jean
Mariani's "Laboratoire de développement et vieillissement
du système nerveux" (Development and Aging of the Nervous
System Laboratory) at CNRS-Université Paris 6. The neuroscience
researchers used a mouse that overexpresses the bcl-2 anti-apoptotic
gene in neuronal cells. These animals have reduced neuron death during
development, which results in larger brains than those of normal mice.
This approach allowed the researchers to examine the consequences
of having more brain cells. They used classic behavioral tests to
see the effects on the animals' ability to learn navigational skills.
They plunged the transgenic mice into a tank of water in which there
was a submerged platform. Over a period of time the mice learned to
find the platform using spatial/visual cues around the swimming pool,
and memorized its location. The CNRS group found that the bcl-2-transgenic
mice had trouble learning this task. They also performed poorly in
tests for motor coordination and equilibrium on a rotating rod. This
study emphasizes the importance of regulated cell death in defining
the brain's ability to cope with complex behavioral tasks based on
learning and memory. It seems that having too many brain cells can
have a detrimental affect on brain function. The researchers hope
that their work on transgenic mouse models will provide important
insights into the role of cell death in human neurodegenerative and
psychiatric disorders.
|
