BIOLOGICAL CLOCK'S SYNCHRONICITY PINPOINTED
Scientists have
uncovered how pacemaker neurons are synchronized at dusk and dawn in order to
maintain the proper functioning of their biological clocks. Their findings,
which appear in the journal PLOS Biology, enhance our
understanding of how sleep-wake cycles are regulated and offer promise for
addressing related afflictions
We've known for some
time that the time-keeping of our biological clocks is a complex
enterprise," says New York University's Justin Blau, a professor of
biology and neural science and one of the study's co-authors. "But our
results offer new details on how clock neurons work together to keep each other
in check."
The study also
included researchers from the University of Michigan and the University of
Houston.
They examined the
biological, or circadian, clocks of Drosophila fruit flies, which are commonly
used for research in this area -- earlier studies of "clock genes" in
fruit flies allowed the identification of similarly functioning genes in humans.
While scientists have
a firm understanding of how biological clocks work within individual cells, it
is less clear how individual cells tick in time together. Such an understanding
is vital so that an organism has one coherent sense of time.
This dynamic was the focus
of the PLOS Biology study.
The researchers
focused on eight master pacemaker neurons (LNvs) located in the central brain
-- these neurons set the timing of the daily transitions between sleep and wake
in the fly.
Specifically, they
examined the signals coming in to these eight LNvs. The researchers found that
LNvs need two synchronizing signals: they signal to each other at dawn and
receive a signal from a second group of clock neurons at dusk. The LNvs start
to desynchronize very quickly in flies lacking either of these synchronizing
signals, showing how active and important this process is. And in flies lacking
both of these signals, the LNvs show weak clock gene rhythms and disrupted
sleep/wake cycles.
The researchers point
out their findings shed new light on what occurs at dusk -- and the
significance of the timing of this signaling.
"Scientists
already knew about the signaling at dawn, but we hadn't previously known about
the signaling that occurs in the evening," explains Blau. "We can see
how delicate this process is-and treatments to desynchronize clocks might even
allow us to reset our clocks more quickly to a new time zone, which would be
invaluable in jetlag."
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