3 September, 2008

Navigation requires constant new neurons

Finding your way, requires a constant renewal of neurons, that says a Japanese research. Scientists halted the production of new neurons on mice, which caused the mice to have a diminished sense of direction and navigation.


Until almost 10 years ago, brainscientists thought that a full-grown adult brain only lost braincells and no new cells were renewed.
Now, thanks to modern microscopic technique it has been shown that new cells are replenished. These cells are commonly formed in the hippocampus, which is important for learning and navigation, and in the olfactory bulb, the part in the brain that registers scent. It has not been shown if these new cells replace or assist the old cells, or that the new cells gain a function in the brain.

Mice with a toxic gene in the preamble of the nervecell were created, to discover what the function of the new cells were. The scientists could aim the toxic gene actively, which directly caused a death of all new form brain cells.

The lack of new brain cells in the hippocampus, had effect on the function. 7 weeks after treatment the mice learned a in consequential week behide which of twelve cubbyholes in a round open field, a dark cubbyhole could be found. But a week later, the treated mice could not remember so well were the dark cubehole was.
It could be concluded that a new supply of brain cells is important for spatial memory.

The part of the brain for scent contained twelve weeks after deactivation of the cellproduction, less cells, but it was striking to notice that the sense of smell capacity was still intact.

Humans, Nature, Neuroscience