In article <m7mHd.10389$pZ4.1796 at newsread1.news.pas.earthlink.net>,
"Allen L. Barker" <alb at datafilter.com> wrote:
> The brain is an amazingly adaptive organ. It is also fundamentally a
> self-organizing system, unlike a television. If the new cells really
> are integrated into the brain they could easily aid in re-learning
> certain functions. They may well be far more plastic than the
> pre-existing neurons, having been recently grown in a dish. In any
> case, assuming that they do make new connections, all of those
> connections are by definition new ones.
This type of plasticity routinely occurs after injury to the brain and
doesn't require new cells to be introduced. Rather it exploits the
latent organisation of the existing structure, bringing less-used
potential organisation structures into play. Any introduced cells would
be unable to participate in this process, lacking the latent
connectivity required, and would be unlikely to grow the required
processes to integrate with the other neurons in the region because some
of the required growth cues are absent. A television was a poor choice
for the analogy in that it lacks this reorganisational capacity, but
it's just wishful thinking to hope that the cells would knit into the
existing structure.
My alarms went off when they claimed to have observed the cells
proliferating using brain imaging - how are they supposed to distinguish
them from the original brain material? In an untreated brain injury,
glial cells proliferate and tissue moves to fill the void, which is what
you would see on any structural scan. If you have a penetrating injury
to the brain, glia move into the rupture, pull the sides together and
after a couple of weeks you are left with a glial scar embedded in a
mass of continuous tissue. I'd love to see the technique which could
detect cultured cells in the midst of this process, without opening the
head. Again, it looks like a lot of wishful thinking to me.
MK.
