NOTE TO JOURNALISTS:
A photo of Arnold Eskin is available on the Web at http://www.uh.edu/media/nr/2005/
02feb/0211005aeskin.html.
BIOLOGICAL CLOCK MAY SHUT
DOWN LONG-TERM MEMORY AT NIGHT
UH Professor Arnold Eskin Receives $2.5 Million
in Grants to Continue Learning, Memory Research
HOUSTON, Feb. 18, 2005 – If you crammed for tests by pulling
‘all nighters’ in school, ever wonder why your memory
is now a bit foggy on what you learned? A University of Houston
professor may have the answer with his research on the role of circadian
rhythms in long-term learning and memory.
Arnold Eskin, the John and Rebecca Moores Professor of Biology and
Biochemistry at UH, was recently awarded two grants totaling $2,472,528
from the National Institutes of Health (NIH) to continue pursuing
his investigations of memory formation and the impact of the biological
clock on learning and memory.
Scientists have known for a while that the brain’s biological
(or circadian) clock influences natural body cycles, such as sleep
and wakefulness, metabolic rate and body temperature. New research
from Eskin suggests the circadian clock also may regulate the formation
of memory at night. This new research focuses on “Circadian
Modulation of Long-term Memory Formation” and “Long-term
Regulation of Glutamate Uptake in Aplysia,” with NIH funding
to be disbursed over four years.
“There is a lot of research going on in memory,” Eskin
said. “How do we remember things given that we don’t
have a camera in our brain to record events? What changes take place
in our brains that allow us to remember? These grants are about
fundamental learning and memory and about modulation of memory.”
For the grant on circadian modulation of long-term memory formation,
Eskin will continue studies based on his data that reveal the circadian
clock modulates several forms of long-term memory in the marine
snail Aplysia.
These studies involved experiments on the defensive reflexes and
feeding responses of Aplysia. Eskin’s results showed that
Aplysia form long-term memory when they are trained during the day
but not when they are trained at night. However, short-term memory
of the same behaviors is formed equally well during the day and
night, which might explain why all-night cram sessions may have
helped you get through certain classes in school, but did not leave
you with enough of a lasting impression to become part of your long-term
store of knowledge.
“Somewhere in the molecular circuit, in the neural circuit
in the brain, the biological clock is shutting that circuit off
at a particular time of night. It’s shutting molecules down
so that long-term memory can’t happen,” Eskin said.
Lisa Lyons, a research assistant professor at UH, is the primary
investigator on this grant and is already investigating molecules
involved in memory formation that might be activated during the
day but not at night. NIH funding will help advance the pursuit
of this line of research.
For the grant on long-term regulation of glutamate uptake in Aplysia,
Eskin will focus on the transmitter substance glutamate, which is
involved in memory formation.
“The formation of memory happens at places in the brain called
synapses, where cells ‘talk’ to one another through
the release of chemicals called transmitter substances,” Eskin
said. “In order for transmitters to work, once they are released
they have got to be cleared away so that others can subsequently
act. So, there are not only important mechanisms to release the
transmitters, but also mechanisms to get rid of them, and these
are called reuptake systems.”
Eskin is studying glutamate reuptake and glutamate transport to
understand the mechanism or change that takes place at the synapses
of nerve cells (or neurons) that enables people to remember. In
previous research, Eskin found that glutamate transport molecules,
which act as the brain’s cleaning crew during learning and
memory formation, actually increase once the long-term memory-forming
process begins. Deficiencies in these glutamate transporters that
affect the strength of connections among the neurons associated
with memory may explain why memory lapses such as forgetting where
you last set down your keys occur.
“This research will provide significant information toward
understanding memory and thus diseases that affect memory,”
Eskin said.
With the potential to shed light upon neurodegenerative diseases
such as Alzheimer’s – marked by a loss of brain function
due to the deterioration of neurons – studying these nerve
cells could one day take this research from helping you be better
able to find your glasses to providing relief from a debilitating
illness.
“At the end of the day, we can’t make memory better
or improve it unless we understand how memory works and is modulated,”
he said. “That’s what this research is all about.”
He is currently completing the last year of another NIH-funded
grant on “Glutamate Transport Regulation and Synaptic Plasticity”
that complements these two new grants, but investigates the role
of glutamate uptake in associative learning in mammals. This research
project on mammals represents a great example of traslational research
in which basic findings in a simple system (i.e. Aplysia) were quickly
applied to a higher organism (i.e. mammals). They found that glutamate
transport increased in the brains of mammals during learning as
also found in Aplysia. (See related release at http://www.uh.edu/admin/media/nr/2002/032002/eskinlearning.html.)
Coming to UH more than 25 years ago, Eskin guided the merger of
two departments into what is now the Department of Biology and Biochemistry
in the College of Natural Sciences and Mathematics. As department
chair from 1994 to 2000, Eskin tripled research grants to approximately
$6 million per year and developed the department’s research
foci of neuroscience, the biological clocks and infectious disease.
The author or co-author of more than 150 publications, he has received
numerous honors, including the Esther Farfel Award, the university’s
highest faculty honor. He is the only faculty member to receive
both the Farfel Award and the Moores Professorship in the same year.
Eskin earned his bachelor’s degree in physics from Vanderbilt
University and his doctorate in zoology from the University of Texas.
UH’s Biological Clocks Program is one of the world’s
leading centers for circadian rhythms research, with five laboratories
and a team of more than 30 scholars. In addition to Eskin, the group
is led by four other tenured faculty members in the biology and
biochemistry department – Associate Professor Gregory M. Cahill,
Professor Stuart Dryer, Professor Paul Hardin and Professor Michael
Rea. For more information on the biological clocks program at UH,
visit http://www.bchs.uh.edu/research_clocks.htm.
SOURCE: Eskin, 713-743-8381; eskin@uh.edu
Web page: http://nsm.uh.edu/faculty.php?155622-961-5=aeskin
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