A group of Korean researchers have succeeded in revealing a
principle mechanism of a neural network in the human brain, which will provide
an important clue to potential treatments for absence seizures. Absence seizures are believed to be elicited by T-type calcium
channels in the thalamic reticular nucleus of the brain that regulate influxes
of calcium. These channels enable thalamic reticular nucleus neurons to
generate burst firing, leading the neurons to enter a hyper-excited state. In order to identify the relationship between burst firing and
absence seizures, the researchers conducted an experiment to induce absence
seizures in mice using gene targeting techniques to delete the T-type calcium
channel CaV3.3. The results showed that mice that received a complete genetic
deletion of the T-type calcium channel, which in turn suppressed burst firing
in the thalamic reticular nucleus, exhibited an increased frequency of absence
seizures. Moreover, the researchers observed for the first time ever that
tonic firing also increased in such mice. The study was the first to discover
that tonic firing plays a key role in the induction of absence seizure, which
contradicts the existing hypothesis and carries significant implications for
absence seizure treatment research. The study is meaningful in respect to the fact that it calls into
question the role of the T-type calcium channel in the reticular thalamus, and
is expected to provide an important theoretical foundation for understanding
its role in the mechanism of absence seizures, as well as developing effective
treatment methods for absence epilepsy.
The
findings were published online, July 28, in the prestigious journal, the Proceedings
of the National Academy of Sciences of the United States of America (PNAS).
Notes for editors -
References
Seung Eun Lee, Jaekwang Lee, Charles Latchoumane, Boyoung Lee, Soo-Jin Oh,
Zahangir Alam Saud, Cheongdahm Park, Ning Sun, Eunji Cheong, Chien-Chang Chen,
Eui-Ju Choi, C. Justin Lee, and Hee-Sup Shin. Rebound burst firing in the
reticular thalamus is not essential for pharmacological absence seizures in
mice. Proc. Natl. Acad. Sci. USA | August 12, 2014 vol. 111 no. 32 11828-11833
| doi:10.1073/pnas.1408609111 (http://www.pnas.org/content/111/32/11828.full) -
Absence seizures
are non-convulsive seizures, characterized by a brief loss of consciousness.
During absence seizures, spike-and-wave discharges, a sudden burst of abnormal
brainwave patterns, can be observed on the electroencephalogram, recurring at a
frequency of about 3 Hz in humans. -
Institute for Basic
Science (IBS) was founded in November 2011 by the Korean government. IBS supports
basic research within the entire range of natural sciences including physics,
biology, chemistry, mathematics, earth science, and astronomy.
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To
speak with Prof. Hee-Sup Shin, please contact: Ms. Jihye Kim, IBS Center for
Cognition and Sociality (+82-2-958-6917; jihye@ibs.re.kr) or Mr. Hanbin Oh, IBS Public Relations Team
(+82-42-878-8182; ohanvin@ibs.re.kr)
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