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The Raelian Movement
for those who are not afraid of the future : http://www.rael.org
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Adult Brain Neurons Can Remodel Connections
http://www.sciencedaily.com/releases/2008/11/081124174909.htm

ScienceDaily (Nov. 27, 2008) — Overturning a century of prevailing
thought, scientists are finding that neurons in the adult brain can
remodel their connections. In work reported in the Nov. 24 online
edition of the Proceedings of the National Academy of Sciences, Elly
Nedivi, associate professor of neurobiology at the Picower Institute
for Learning and Memory, and colleagues found that a type of neuron
implicated in autism spectrum disorders remodels itself in a strip of
brain tissue only as thick as four sheets of tissue paper at the upper
border of cortical layer 2.

"This work is particularly exciting because it sheds new light on the
potential flexibility of cerebral cortex circuitry and architecture in
higher-level brain regions that contribute to perception and
cognition," said Nedivi, who is also affiliated with MIT's departments
of brain and cognitive sciences and biology. "Our goal is to extract
clues regarding the contribution of structural remodeling to long-term
adult brain plasticity — the brain's ability to change in response to
input from the environment — and what allows or limits this
plasticity."

In a previous study, Nedivi and Peter T. So, professor of mechanical
engineering and biological engineering at MIT, saw relatively
large-scale changes in the length of dendrites — branched projections
of nerve cells that conduct electrical stimulation to the cell body.
Even more surprising was their finding that this growth was limited to
specific type of cell. The majority of cortical neurons were stable,
while the small fraction of locally connecting cells called
interneurons underwent dynamic rearrangement.

In the current study, they show that the capacity of interneurons to
remodel is not predetermined by genetic lineage, but imposed by the
circuitry within the layers of the cortex itself. "Our findings
suggest that the location of cells within the circuit and not
pre-programming by genes determines their ability to remodel in the
adult brain," Nedivi said. "If we can identify what aspect of this
location allows growth in an otherwise stable brain, we can perhaps
use it to coax growth in cells and regions that are normally unable to
repair or adjust to a changing environment.

"Knowing that neurons are able to grow in the adult brain gives us a
chance to enhance the process and explore under what conditions we can
make it happen," Nedivi said. "In particular, we need to pay more
attention to the unique interneuron population that retains special
growth features into adulthood."

In addition to Nedivi and So, authors are Brain and Cognitive Sciences
graduate student Wei-Chung Allen Lee; Biology graduate students
Jennifer H. Leslie and Jerry L. Chen; MIT research affiliate Hayden
Huang; and Yael Amitai of Ben-Gurion University in Israel.

This work is supported by the National Eye Institute.

Adapted from materials provided by Massachusetts Institute of Technology.