Dendritic spines: Revisiting the physiological role

• Published in: Progress in neuro-psychopharmacology & biological psychiatry 2019-06, Vol.92, p.161-193
• Main Authors: Chidambaram, Saravana Babu, Rathipriya, A.G., Bolla, Srinivasa Rao, Bhat, Abid, Ray, Bipul, Mahalakshmi, Arehally Marappa, Manivasagam, Thamilarasan, Thenmozhi, Arokiasamy Justin, Essa, Musthafa Mohamed, Guillemin, Gilles J., Chandra, Ramesh, Sakharkar, Meena Kishore
• Format: Article
• Language: English
• Subjects: Dendritic spine pathology; Dendritic spines; Neurological diseases; Spine dynamics; synaptic plasticity
• ISSN: 0278-5846; 1878-4216
• DOI: 10.1016/j.pnpbp.2019.01.005

Dendritic spines are small, thin, specialized protrusions from neuronal dendrites, primarily localized in the excitatory synapses. Sophisticated imaging techniques revealed that dendritic spines are complex structures consisting of a dense network of cytoskeletal, transmembrane and scaffolding molecules, and numerous surface receptors. Molecular signaling pathways, mainly Rho and Ras family small GTPases pathways that converge on actin cytoskeleton, regulate the spine morphology and dynamics bi-directionally during synaptic activity. During synaptic plasticity the number and shapes of dendritic spines undergo radical reorganizations. Long-term potentiation (LTP) induction promote spine head enlargement and the formation and stabilization of new spines. Long-term depression (LTD) results in their shrinkage and retraction. Reports indicate increased spine density in the pyramidal neurons of autism and Fragile X syndrome patients and reduced density in the temporal gyrus loci of schizophrenic patients. Post-mortem reports of Alzheimer’s brains showed reduced spine number in the hippocampus and cortex. This review highlights the spine morphogenesis process, the activity-dependent structural plasticity and mechanisms by which synaptic activity sculpts the dendritic spines, the structural and functional changes in spines during learning and memory using LTP and LTD processes. It also discusses on spine status in neurodegenerative diseases and the impact of nootropics and neuroprotective agents on the functional restoration of dendritic spines. •Detailed review of dendritic spine structure, morphology and morphogenesis, volumetric alterations of dendritic spines in various neurological diseases is summarised.•Spine density is generally believed to get stabilized during adult life, but recent research analyses reveal that learning, practising and training new skills indeed causes remarkable morphological and volumetric changes in spine turnover, which in turns alters the neural circuitry.•Advanced development in higher resolution imaging techniques describe the molecular structural role of the dendritic spines in new synapse formation and alteration in the neural circuits.•The manuscript gives details on the alterations of dendritic spine using LTP and LTD stimulations, status in various neurodegenerative diseases•Effects of various pharmacological agents on dendritic spines and synapses status are also discussed.