Circadian Rhythm the
Fortune Teller
Despite the name, circadian rhythm has
nothing to do with drums, counting beats or anything musical for that matter.
Instead, it is one of the most complex, interesting and widely studied concepts
in the biological and neuroscience fields. On September 22nd 2015,
our neuroscience 300 class at Loyola University Chicago was lucky enough to
have guest speaker Dr. Daniel J. Cavanaugh introduce the concept of Circadian
Rhythms and explain his research as well.
First, Dr. Cavanaugh defined what a
Circadian Rhythm is. Also referred to as the biological clock, a circadian rhythm
is a 24-hour cycle that regulated many physiological properties. The ’24-hour’ definition
is based on the fact that the circadian rhythm is coordinated with the cycle of
light (day) and dark (night) and thus carries out functions accordingly. An
example of a physiological property that Dr. Cavanaugh supplies is the circadian
rhythm regulates is hormone secretion for sleep. Melatonin is a hormone that functions
in sleep and is actively released at nine o’clock at night specifically. With
the increase of melatonin in the blood stream, you find yourself less alert and
more tired. This is a classic example of the importance of the circadian
rhythm. Melatonin is a hormone that helps the body to become less active and
assist in entering sleep, thus it must be released during the night rather than
during the day. Otherwise humans would not be able to function properly throughout
the day but would actually feel less active and less alert. Another example is the
function of the circadian rhythm in learning and memory in the fruit fly Drosophila. The fruit flies are
conditioned to discriminate between two scents after one was linked with an
electric shock punishment. This training induced a short-term memory regarding
which odor produced which outcome, however the ability for the formation of
this memory was dependent upon the circadian clock. The peak memory formation
was specifically in either light dark or constant dark conditions, indicating that
the circadian rhythms has influence over learning, and memory formation, as
there are specific and optimal conditions.
According to recent research, the
circadian clock also functions in determining when an individual falls ill. Researchers
at Yale University conducted a study that examined the success of a vaccination
and its correlation to the circadian rhythm. The study found that the circadian
rhythm influences the levels of a protein called TLR9, this is a protein that
works with the immune system and the levels vary throughout the day. In the
study, the mice were infected with bacteria in different times of the day, when
TLR9 was at peak or when it was low. Results show that exposure to bacteria at
low levels resulted in severe sepsis and sooner death than those exposed during
high levels. Furthermore, the study also showed that vaccination during high
levels of TLR9 resulted in a stronger immune response than vaccination during
low levels. This is parallel to the fruit flies ability to form short-term
memory at an optimal timing. Just as there is an optimal time for memory
formation in fruit flies there is an optimal time for infection and
vaccination. This is also parallel to Dr. Cavanaugh’s example; as there is an
optimal time for melatonin release just as there is an optimal time for
infection and vaccination.
Although there is ongoing research in
circadian rhythms, the current studies and results represent the importance of
the circadian rhythms. Circadian rhythms regulate physiological processes that
vary from the immune system to the function of the brain. Circadian rhythms may
not hold all the answers, however it is very possible that studying them will
lead to other innovations that can answer many questions. For example, since
circadian rhythms function according to timing, is there an optimal timing for
cellular division to occur, with the appropriate functioning of the cellular
division check points? If so, does this optimal timing reduce the risk of
cancer? Hopefully, future research will answer such a minute question and other
complex ones.
Citations:
O'CONNOR, ANAHAD.
"WELL; Really? The Claim: Your Body Clock Can Determine When You Get
Sick." The New York Times. The New York Times, 28 Feb. 2012. Web.
15 Oct. 2015.
Reece, Jane B., and
Neil A. Campbell. Campbell Biology / Jane B. Reece ... Boston: Benjamin
Cummings, 2014. Print.
No comments:
Post a Comment