Conference 2021 Pre-Recorded Video


Project title

Deleting Neurons: A closer look at Synaptic Pruning


Authors and Affiliations

Anjali Sharma1, Max Shanahan2

1. Department of Biochemistry, University of Delhi, Delhi, India
2. Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland




The overproduction of neural elements, including neurons, axons, and synapses, is a tool commonly used in developmental neuroscience to reconstruct nervous systems. This generation and maturation of these neuronal synapses are accompanied by a peak in synaptic pruning which eliminates extra neurons and synaptic connections to increase the efficiency of neuronal transmissions along with eliminating weaker synaptic contacts while stronger connections are kept and strengthened. Neurons that are more frequently activated are preserved, while those forming weaker synaptic contacts are “trimmed away.”. In this review, we explore the brain’s innate “delete” button and present current data on the mechanisms of glial-cell-dependent synaptic pruning by outlining their potential contribution to neurodevelopmental disorders.


The complex nature of synaptic pruning and the role in neurodegenerative and neurodevelopmental disorders was studied in this study by conducting a comprehensive systematic review using Connected Papers, CoCites and Citation Gecko tools. We searched articles on electronic databases using terms such as “Synaptic Pruning” OR “Synaptic Pruning Neurodegeneration” AND “Brain Plasticity” OR “Brain Plasticity Neurodegeneration” AND “Neural Pruning”. Recent studies published in English language from the time period(years) 2005-2020 were included in the review.


After removing the duplicates, protocol paper and those not meeting inclusion criteria, 15 articles were identified to fulfil the criteria among 24 articles identified in the search. All of the reviewed papers were randomized controlled studies. Brain imaging and postmortem anatomical studies have pointed to insufficient or excessive synaptic pruning that may underlie several neurodevelopmental disorders, including autism, schizophrenia, and epilepsy. Microglial Cells play a critical role in synaptic pruning, mediated by a set of signalling pathways between neurons and glia, identifying and removing unnecessary neural connections. This loss of redundant pathways may explain the arduous task of recovering from a traumatic brain injury; eliminating synaptic redundancies diminishes our ability to develop alternative pathways to bypass the damaged regions.


This review highlights the most recent findings demonstrating how the dynamic interactions between hippocampus neurons and microglia shape the synaptogenesis and synaptic pruning in a healthy brain.