The Journal of Neuroscience, October 1, 2002, 22(19):8614-8618
Identification of Munc13-3 as a Candidate Gene for
Critical-Period Neuroplasticity in Visual Cortex
Cui Bo
Yang1,
Yu Ting
Zheng2,
Guang Yu
Li1, and
George D.
Mower1
Departments of 1 Anatomical Sciences and Neurobiology
and 2 Physiology and Biophysics, University of Louisville
School of Medicine, Louisville, Kentucky 40202
The first several months of life are a critical period for neuronal
plasticity in the visual cortex during which anatomic and physiological
development depends on visual experience. In cats,
electrophysiologically assessed neuronal plasticity is minimal until
~3 weeks, peaks at 5 weeks, gradually declines to low levels at 20 weeks, and disappears at ~1 year of age (Daw, 1994). Rearing in
darkness slows the entire time course of this critical period, such
that at 5 weeks of age, normal cats are more plastic than dark-reared
cats, whereas at 20 weeks, dark-reared cats are more plastic (Mower,
1991; Beaver et al., 2001). Thus, a stringent criterion is that genes
that are important for plasticity in visual cortex will show
differences in expression between normal rearing and dark rearing that
are of opposite direction in young versus older animals. The present
study reports the identification by differential display PCR of
Munc13-3, a mammalian homolog of the Caenorhabditis
elegans "uncoordinated" gene (unc-13), as a
candidate gene for critical-period neuronal plasticity, the expression
of which is regulated according to this criterion specifically in visual cortex and not in frontal cortex. Other members of the Munc13
family (Munc13-1 and Munc13-2) do not meet this criterion in visual
cortex, indicating that Munc13-3 is the only family member that is
regulated by age and dark rearing in the same manner as physiological
plasticity during the visual cortical critical period.
Key words:
visual cortex; Munc13; critical period; dark rearing; differential display PCR; neuronal plasticity
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