In article <Pine.OSF.3.91.960724170110.9837A-100000 at axp2.cns.ox.ac.uk>,
Simon Schultz <schultz at axp2.cns.ox.ac.uk> wrote:
>>In 1982 it was reported that in rats, dentate granule cells continued to
>be added to the hippocampus over the whole first year of life (no results
>for thereafter) (Bayer et al 1982, Science 218:890-892). Does anyone know
>of any evidence since then that this is a real phenomenon, and whether it
>transfers across species?
There have been many papers since Bayer's 1982 article which have
replicated the finding with tritiated thymidine and bromodeoxyuridine as
indicators of cell division. A number of studies have done double
labeling for neuron/glial specific proteins and shown that the majority
of these new cells are neurons. This belief depends on Neuron Specific
Enolase (NSE) actually being neuron specific and GFAP and Vimentin being
glia specific. There was another neuronal specific marker used as well,
but I can't remember what it was. For a recent example look for Khun et
al. 1996 in the Journal of Neuroscience. Seki and Arai (1993, J.
Neurosci.) showed that these new neurons transiently express the highly
polysialyated neural cell adhesion molecule (NCAM-H) which is thought to
be associated with developing neural tissue and the reorganization of
synaptic contacts. There was also a paper which showed that these young
neurons could be antidromically stimulated (presumabely through axons)
from the CA3 region. Anyway, look for names such as Crespo D., Stanfield
B., Cowan WM, Kaplan MS which are associated with neurogenesis in the
adult rat and mouse.
>>West and Gunderson (1989, J. Comp. Neurol. 296:1-22) found no evidence of
>continual addition of granule cells in the human, although there were
>only 5 specimens and they started at just under 50 years.
Rakic P. has looked for this in primates and has not found it. I know it
occurs in rabbits and have heard of it in hamsters.
Brian Scott | "In other studies you go as far as others have gone
brians at interlog.com | before you, and there is nothing more to know; but
M.Sc. student in | in scientific pursuit there is continual food for
Neurophysiology | discovery and wonder." - Victor Frankenstein