Developmental presence and disappearance of postsynaptically silent synapses on dendritic spines of rat layer 2/3 pyramidal neurons

被引:54
作者
Busetto, Giuseppe [1 ,2 ]
Higley, Michael J. [1 ]
Sabatini, Bernardo L. [1 ]
机构
[1] Harvard Univ, Sch Med, Dept Neurobiol, Boston, MA 02115 USA
[2] Univ Verona, Dipartimento Sci Neurol & Vis, Sez Fisiol, I-37134 Verona, Italy
来源
JOURNAL OF PHYSIOLOGY-LONDON | 2008年 / 586卷 / 06期
关键词
D O I
10.1113/jphysiol.2007.149336
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Silent synapses are synapses whose activation evokes NMDA-type glutamate receptor (NMDAR) but not AMPA-type glutamate receptor (AMPAR) mediated currents. Silent synapses are prominent early in postnatal development and are thought to play a role in the activity- and sensory-dependent refinement of neuronal circuits. The mechanisms that account for their silent nature have been controversial, and both presynaptic and postsynaptic mechanisms have been proposed. Here, we use two-photon laser uncaging of glutamate to directly activate glutamate receptors and measure AMPAR- and NMDAR-dependent currents on individual dendritic spines of rat somatosensory cortical layer 2/3 pyramidal neurons. We find that dendritic spines lacking functional surface AMPARs are commonly found before postnatal day 12 (P12) but are absent in older animals. Furthermore, AMPAR-lacking spines are contacted by release-competent presynaptic terminals. After P12, the AMPAR/NMDAR current ratio at individual spines continues to increase, consistent with continued addition of AMPARs to postsynaptic terminals. Our results confirm the existence of postsynaptically silent synapses and demonstrate that the morphology of the spine is not strongly predictive of its AMPAR content.
引用
收藏
页码:1519 / 1527
页数:9
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