On Tue, 4 May 1999, Dr. Kristina Lewis went:
> ....because some types of neurons are replenished
>
> and what about this? I thought that no new neurons were produced after
> birth (in fact few after 28 weeks)--backed up by a number of references in
> several developmental texts.
The "no new neurons" generalization--one I always used to make with
foolish confidence--is getting increasingly untenable. For a decade
or two, folks have known about neurogenesis in the dentate gyrus of
the adult rat hippocampus, but no one seemed to mention it much. Now
we know that it also occurs in humans (see reference below). A few
months ago, I heard a talk (I forget the speaker's name) at which it
was argued that adult humans probably generate new neurons in several
other multiple brain regions, such as prefrontal cortex, and that this
may happen all the time. What we're _doing_ with the new neurons is
unknown.
--a very perplexed
David Epstein
[EMAIL PROTECTED]
TAKE COMFORT IN HUMAN NEUROGENESIS [editorial]
Nature Medicine 4(11):1207, 1998 Nov.
Eriksson PS. Perfilieva E. Bjorkeriksson T. Alborn AM. Nordborg C.
Peterson DA. Gage FH.
NEUROGENESIS IN THE ADULT HUMAN HIPPOCAMPUS
Nature Medicine 4(11):1313-1317, 1998 Nov.
Abstract
The genesis of new cells, including neurons, in the adult human brain has
not yet been demonstrated. This study was undertaken to investigate
whether neurogenesis occurs in the adult human brain, in regions
previously identified as neurogenic in adult rodents and monkeys. Human
brain tissue was obtained postmortem from patients who had been treated
with the thymidine analog, bromodeoxyuridine (BrdU), that labels DNA
during the S phase. Using immunofluorescent labeling for BrdU and for one
of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE),
we demonstrate that new neurons, as defined by these markers, are
generated from dividing progenitor cells in the dentate gyrus of adult
humans. Our results further indicate that the human hippocampus retains
its ability to generate neurons throughout life.
