Anatomical and Physiological Plasticity of Dendritic Spines

Abstract

In excitatory neurons, most glutamatergic synapses are made on the heads of dendritic spines, each of which houses the postsynaptic terminal of a single glutamatergic synapse. We review recent studies demonstrating in vivo that spines are motile and plastic structures whose morphology and lifespan are influenced, even in adult animals, by changes in sensory input. However, most spines that appear in adult animals are transient, and the addition of stable spines and synapses is rare. In vitro studies have shown that patterns of neuronal activity known to induce synaptic plasticity can also trigger changes in spine morphology. Therefore, it is tempting to speculate that the plastic changes of spine morphology reflect the dynamic state of its associated synapse and are responsible to some extent for neuronal circuitry remodeling. Nevertheless, morphological changes are not required for all forms of synaptic plasticity, and whether changes in the spine shape and size significantly impact synaptic signals is unclear.

Dopaminergic signaling in dendritic spines

“…This morphological heterogeneity may correspond to differences in strengths of synapses established on these spines. Spines show a remarkable dynamics in vivo and their formation, elimination, and morphological/structural plasticity are regulated during development, and by sensory experience [20].…”

“…A number of organelles are found in dendritic spines that support spines as structurally autonomous units for synaptic transmission, signaling, and plasticity [18][19][20]. All spines contain smooth endoplasmic reticulum (SER), which is involved in membrane synthesis and intracellular Ca2+ handling.…”

“…This morphological heterogeneity may correspond to differences in strengths of synapses established on these spines. Spines show a remarkable dynamics in vivo and their formation, elimination, and morphological/structural plasticity are regulated during development, and by sensory experience [20].A number of organelles are found in dendritic spines that support spines as structurally autonomous units for synaptic transmission, signaling, and plasticity [18][19][20]. All spines contain smooth endoplasmic reticulum (SER), which is involved in membrane synthesis and intracellular Ca2+ handling.…”

Highly sensitive and quantitative FRET–FLIM imaging in single dendritic spines using improved non-radiative YFP

“…Biochemical signaling in spines is important for many forms of synaptic plasticity and structural plasticity of spines (Alvarez and Sabatini, 2007;Kennedy et al, 2005). Because signaling in each dendritic spine is regulated differently (Alvarez and Sabatini, 2007;Kennedy et al, 2005), the coupling between synaptic activity and intracellular signaling has to be studied ultimately at the level of individual spines. However, due to the small size of dendritic spines (∼femtoliter), and light scattering by brain tissue, it has been difficult to measure the molecular signaling in spines.…”

Molecular and cellular mechanisms of dendritic morphogenesis

“…The application of genetic approaches to identifiable central or peripheral neurons in intact animals, especially Drosophila, has provided mechanistic insights into dendritic outgrowth and branching, dendritic targeting, and self-recognition [6][7][8][9][10]. In this review, it is impossible to cover all recent relevant studies, such as dendritic maintenance [10], spine formation [11] or regulation by neuronal activity [12,13]. Instead, I will focus on transcriptional control, role of membrane protein trafficking, dendritic targeting and self-recognition and highlight some exciting new progresses mostly in Drosophila and challenges ahead.…”