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Born
and raised in the Netherlands, Henriette van Praag emigrated
to Israel after high school, where she received her
B.A. in Psychology from Bar-Ilan University in Ramat-Gan.
In 1992, she received her Ph.D. from the department
of Psychobiology at Tel-Aviv University for her work
studying the development of opiate receptor function.
Van
Praag then came to the United States, where she did
her post-doctoral research on the role of nerve growth
factors in brain injury at the University of Medicine
and Dentistry of New Jersey. She continued her research
in brain regeneration after injury and diseases at the
Laboratory of Genetics at the Salk Institute for Biological
Studies in La Jolla, California. Van Praag's current
research focuses on the regulation of the birth of new
neurons in the adult hippocampus, a brain area that
is important in learning and memory. She and her colleagues
hope that if they can understand these mechanisms, they
may discover ways to enhance brain repair or even induce
'self-repair'.
When she's not in the lab, van Praag enjoys hiking,
bicycling, gardening and reading.
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van
Praag responds :
 12.01.00
Dick Watrous asked:
Does any of your research give any hope for stroke victims
and disabilities associated with this condition? |
van
Praag's response:
Studies
in gerbils have shown that housing with a running wheel
before stroke reduced mortality and the amount of brain
damage. In addition, the recovery from stroke was better
than in the control group. |
12.01.00
John McLaughlin asked:
What signals to the hippocampus are most likely to trigger
new cell growth based on prolonged exercise? Could extensive
running change factors in the blood (sugar concentrations,
oxygen levels, etc.?) and thus signal new cell growth?
Can waste products from anaerobic "stress" from running
serve as potential signals to cause the brain to grow
and thus possibly avoid future situations where such extensive
exercise is necessary? Also, how do your findings relate
to recent work which found that moderate exercise can
help reduce feelings of depression in some people? |
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van
Praag's response:
We
are currently investigating which factors may mediate
enhanced cell growth in the hippocampus. Possibilities
raised are, as you suggested, increased blood flow and
oxygen levels. Specific factors we are studying are
growth factors (insulin-like growth factors, nerve-growth
factor) and certain neurotransmitters such as serotonin.
We
have not looked into a role for waste products as a
trigger for the growth of new cells. Our studies suggest
that a certain amount of regular exercise is necessary
to maintain new cells over time.
Exercise has been shown to increase levels of serotonin
in the brain. The production of serotonin is stimulated
by the use of anti- depressants such as fluoxetine or
Prozac. Recent research has shown that the generation
of new cells can be stimulated directly by administration
of serotonergic drugs. In addition, stress and depression
have been associated with a loss of brain cells from
the hippocampus. One could speculate that exercise is
beneficial for depression by activation of the serotonergic
system and/or production of new brain cells.
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12.01.00
Phil asked:
How many neurons does a person have? How many neurons
does a mouse have? I am now running 5 miles a day. |
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van
Praag's response:
A
person has about 10 to the power 10 neurons. A mouse
has approximately 10 the power 7 neurons.
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12.01.00
Fred Eisele asked:
Given that mice enjoy running so much (well at least they
do it a lot, 5 km/night, wow) do you have evidence that
it is the exercise and not their enjoyment? Or, to put
it another way, does exercise have to be enjoyed to see
the benefit? |
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van
Praag's response:
There is no objective method to assess enjoyment in
mice. There are measurements that are indicative of
stress, such as levels of certain hormones in the blood.
Stress has been found to decrease the birth of new brain
cells and impair memory. So if exercise is stressful,
one may assume that its beneficial effects are reduced.
We have measured stress hormone (corticosteroid) levels
in our mice and found no difference in comparison with
control mice.
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12.01.00
Matthew McGoldrick asked:
As you grow older, how do you continue to gain brain cells,
thus gaining knowledge and memory? |
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van
Praag's response:
The generation of new cells in the adult hippocampus
continues throughout life. The number of cells that
are produced declines with aging. An enriched environment
can increase cell production in aged mice and improve
memory function. We are currently investigating whether
exercise increases generation of new cells in the hippocampus
(a brain region involved in learning and memory) as
well.
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