The Journal of Neuroscience, December 15, 2001, 21(24):9724-9732
Experience-Dependent Plasticity of Mouse Visual Cortex in the
Absence of the Neuronal Activity-Dependent Marker
egr1/zif268
Nobuko
Mataga1,
Sayaka
Fujishima1,
Brian G.
Condie2, and
Takao K.
Hensch1
1 Laboratory for Neuronal Circuit Development, Brain
Science Institute, RIKEN, 351-0198 Japan, and
2 Departments of Medicine and Cellular Biology and Anatomy,
Institute for Molecular Medicine and Genetics, Medical College
of Georgia, Augusta, Georgia 30912
Neuronal activity elicits a rapid increase in the expression of
several immediate early genes (IEGs). To clarify a role for IEG
response in activity-dependent development, we examined the contribution of the egr1/zif268 gene during visual
cortical processing and plasticity in mice. We first analyzed the
expression of egr1 mRNA in wild-type (WT) mice using
Northern blot hybridization. In the visual cortex, expression of
egr1 mRNA increased dramatically after eye opening,
systemic injection of kainate, or 30 min of photostimulation after a
brief (5 d) period of dark adaptation. Thus, the expression of
egr1 is regulated by synaptic activity in the mouse
visual cortex, as it is in other species (e.g., monkeys, cats, and rats).
To evaluate whether this transcription factor is directly involved in
activity-dependent plasticity, mice lacking Egr1 were deprived of the
use of one eye during the developmental critical period [postnatal day
24 (P24)-P34]. Extracellular in vivo single-unit recordings from the binocular zone of the visual cortex revealed that
visual responses developed normally in egr1 knock-out
(KO) mice. Moreover, a similarly significant shift of responsiveness in
favor of the open eye was produced in both KO and WT mice by either
brief (4 d) or long-term (>2 weeks) occlusion of one eye. There was no
apparent compensation among egr2, egr3,
or c-fos mRNA and protein expression in the visual
cortex of egr1 KO mice.
Taken together, these results indicate that egr1
is a useful marker of sensory input in mice but is not intrinsically
necessary for the experience-dependent plasticity of the visual cortex. Our findings underscore a mechanistic distinction between sensory plasticity and long-lasting forms of synaptic potentiation in the
hippocampus, for which egr1/zif268 was recently found to
be essential.
Key words:
immediate early gene; transcription factor; monocular
deprivation; ocular dominance; development; activity-dependent
plasticity
Copyright © 2001 Society for Neuroscience 0270-6474/01/21249724-09$05.00/0