Microglia in the developing somatosensory "barrel" cortex

Title：Microglia in the developing somatosensory "barrel" cortex

Speaker：Dr. Etienne Audinat（Inserm U603, CNRS UMR8154, Paris Descartes University, France）

Date/Time：June 5, 2012 (Tue) 16:00 - 17:00

Place：3F Seminar room, Nanobiology Building

Abstract：
Accumulative evidence indicates that microglial cells influence the normal development of brain synapses. Yet, the mechanisms by which these immune cells target maturating synapses and influence their functional development at early postnatal stages remain poorly understood. Our recent work focuses on the roles of microglia in the whisker-related barrel field of the mouse somatosensory cortex during the first weeks of the postnatal development. In particular, we have analyzed the role of CX3CR1, a microglial receptor activated by the neuronal chemokine CX3CL1 (or fractalkine) and which controls key functions of microglial cells. Our results show that the recruitment of microglia to the sites where developing thalamo-cortical synapses are concentrated (i.e. the barrel centers) occurs only after postnatal day 5 and is controlled by the fractalkine/CX3CR1 signaling pathway. Indeed, at this developmental stage fractalkine is over-expressed within the barrels and CX3CR1 deficiency delays microglial cell recruitment into the barrel centers. Functional analysis of thalamo-cortical synapses shows that CX3CR1 deficiency also impairs the functional maturation of postsynaptic glutamate receptors which normally occurs at these synapses between the first and second postnatal week. These results indicate that reciprocal interactions between neurons and microglial cells control the functional maturation of cortical synapses.