CONNECTIONS in the nervous system
Early Development of the Nervous System:
“One of the grand strategies nature uses to construct nervous systems is to overproduce neural elements, such as neurons, axons and synapses, and then prune the excess. In fact, this overproduction is so substantial that only about half of the neurons mammalian embryos generate will survive until birth.” … “1979 … Peter Huttenlocher …demonstrated that this excess production and pruning strategy actually continues for synapses long after birth. … he showed that synapses … proliferate after birth, reaching twice their neonatal levels by mid- to late childhood, and then decrease precipitously during adolescence. … These changes at the synapse level cause neural restructuring that very likely has important consequences for normal and abnormal brain function.” (Read the entire (brief) article on-line at https://www.scientificamerican.com/article/why-is-synaptic-pruning-important-for-the-developing-brain/ (Irwin Feinberg for Scientific American MIND, May 1 2017 comments on “Why Is Synaptic Pruning Important for the Developing Brain?”)
Between ages 11 and 17, children’s brain waves reduce significantly while they sleep, a new study found. Scientists think this change reflects a trimming-down process going on inside during these years, where extraneous mental connections made during childhood are lost.” … “The fact that there are more connections [in a child’s brain] allows things to be moved around,” Campbell told . “After adolescence, that alternate route is no longer available. You lose the ability to recover from a brain injury, or the ability to learn a language without an accent. But you gain adult cognitive powers.” (Read March 23, 2009. “Teen Brains Clear Out Childhood Thoughts.” on line at: https://www.livescience.com/3435-teen-brains-clear-childhood-thoughts.html)
CONNECTIONS in the BRAIN:
- CNS DEVELOPMENT and SYNAPTIC OVERGROWTH and PRUNING
- CONNECTIONS in COMPETITION In the brain, connectivity is determined at first by genetics of growth and apoptosis and then by competition.
- The “DARK SIDE” of CONNECTIONS POST we can have too many connections. (helps to have biological grounding in the development and dissolution of connections in the developing brain (see the READING on brain-development-and-the-role-of-experience)