Why are so many synapses lost, what determines which synapses are eliminated, what are the molecular mechanisms involved, and what are the consequences of not getting it right Recently, several studies have presented microglial phagocytosis as a mechanism for synapse elimination
In 1975, Brian Cragg first documented a phase of rapid increase in synapses, followed by a phase of synapse elimination in the visual area of the cat brain.
This is followed by a second phase, during which the rate of synapse elimination exceeds the rate of synapse formation.
Further analysis of their data caused Rakic and his colleagues to conclude that decreases in synaptic density were due to genuine synapse elimination in the brain, not to the number of synapses remaining constant while the brain grew in volume.
Synapse elimination also appeared to be on different timetables in the two areas.
Synapse elimination beginning at puberty reduces densities to adult levels.
Fragile-X syndrome may result from a developmental failure that prevents synaptic maturation and proper synapse elimination during development.