Synaptic pruning

A model view of the synapse

Synaptic pruning, a phase in the development of the nervous system, is the process of synapse elimination that occurs between early childhood and the onset of puberty in many mammals, including humans.[1] Pruning starts near the time of birth and continues into the late-20s.[2] During the pruning of a synapse, both the axon and the dendrite decay and die off. Synaptic pruning was traditionally considered to be complete by the time of sexual maturation, but MRI studies have discounted this idea.[3]

The infant brain will increase in size by a factor of up to 5 by adulthood, reaching a final size of approximately 86 (± 8) billion neurons.[4] Two factors contribute to this growth: the growth of synaptic connections between neurons and the myelination of nerve fibers; the total number of neurons, however, remains the same.[citation needed] After adolescence, the volume of the synaptic connections decreases again due to synaptic pruning.[5]

Pruning is influenced by environmental factors and is widely thought to represent learning.[5][need quotation to verify]

  1. ^ Chechik, G; Meilijson, I; Ruppin, E (1998). "Synaptic pruning in development: a computational account". Neural Computation. 10 (7): 1759–77. CiteSeerX 10.1.1.21.2198. doi:10.1162/089976698300017124. PMID 9744896. S2CID 14629275.
  2. ^ "Brain's synaptic pruning continues into your 20s". New Scientist. Retrieved 2018-06-19.
  3. ^ Iglesias, J.; Eriksson, J.; Grize, F.; Tomassini, M.; Villa, A. (2005). "Dynamics of pruning in simulated large-scale spiking neural networks". BioSystems. 79 (9): 11–20. Bibcode:2005BiSys..79...11I. doi:10.1016/j.biosystems.2004.09.016. PMID 15649585.
  4. ^ Azevedo, Frederico A.C.; Carvalho, Ludmila R.B.; Grinberg, Lea T.; Farfel, José Marcelo; Ferretti, Renata E.L.; Leite, Renata E.P.; Filho, Wilson Jacob; Lent, Roberto; Herculano-Houzel, Suzana (2009). "Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain". The Journal of Comparative Neurology. 513 (5): 532–41. doi:10.1002/cne.21974. PMID 19226510. S2CID 5200449.
  5. ^ a b Craik, F.; Bialystok, E. (2006). "Cognition through the lifespan:mechanisms of change". Trends in Cognitive Sciences. 10 (3): 131–138. CiteSeerX 10.1.1.383.9629. doi:10.1016/j.tics.2006.01.007. ISSN 1364-6613. PMID 16460992. S2CID 11239746.