![]() ![]() Following years of speculations, it was only in 1959 with the development of electron microscopy (EM) that spines were confirmed to be the points of contact between neurons, by forming the postsynaptic element of synapses ( Gray, 1959). Towards the end of the century, theories emerged proposing that changes in brain activity and function could be driven by morphological modifications of spines (reviewed by DeFelipe, 2015). He proposed them to be points of contact between neurons. Ramón y Cajal in 1888 was the first to observe these small protrusions 1.0–1.5 μm in length in Golgi stainings ( Cajal, 1888). Here, we review several emerging concepts in the field that start to answer the following key questions: What are the external signals triggering spine dynamics and the molecular mechanisms involved? What is, in return, the role of spine dynamics in circuit-rewiring, learning, and neuropsychiatric disorders?ĭendritic spines are the postsynaptic sites of most excitatory synapses, found along the dendrites of neurons. Spine dynamics comprise formation, disappearance, and stabilization of spines and are modulated by neuronal activity and developmental age. It is only a decade ago that two-photon microscopy (TPM) has unambiguously proven the dynamic nature of spines, through the repeated imaging of single spines in live animals. The finding that spine density decreases between young and adult ages in fixed tissues suggested that spines are dynamic. Around 50 years later the advance of electron microscopy (EM) confirmed Cajal’s intuition that spines constitute the postsynaptic site of most excitatory synapses in the mammalian brain. Institut de Neurobiologie de la Méditerranée (INMED) INSERM U1249, Aix-Marseille University, Marseille, Franceĭendritic spines are small protrusions studding neuronal dendrites, first described in 1888 by Ramón y Cajal using his famous Golgi stainings.Karen Runge, Carlos Cardoso and Antoine de Chevigny *
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