EAR-20 Lecture 15: EAR-20 - Day 15
Keenan Lieu
Spring 2020
Child Growth and Development
Glial Cells and Myelination
● An estimated ten times more glial cells than neurons also form within the brain
● Glial cell: brain cell that provides a scaffolding for neurons migration and that nourishes
neurons and assists in the production of myelin
● These cells comprise about half the volume of the brain and instruct the neurons to form
synapses with other neurons
● One type of glial cell has another critical function: to provide the material from which
myelin, the sheath of fatty substance (of described as white matter) that surrounds the
axons of many neurons, is formed
● Myelin: sheath of fatty cells that insulates and speeds neural impulses up to 100 times
faster than when its absent
Plasticity in Brain Development
● Because of the unspecialized nature of young neurons, the immature brain displays
substantial plasticity or the ability
● Plasticity: capacity of immature systems, including regions of the brain (cerebral cortex)
and the individual neurons within those regions, to take on different functions
(specialized sensory, linguistics, etc.) as a result of experience
● Infants or children who suffer damage to regions of the cerebral cortex that
process speech for example are often able to recover because neurons in other
parts of the cortex take on this function
● Although considerable plasticity is retained by some regions of the mature adult brain,
the prognosis for recovery of language in adults after an accident or stroke is usually
much poorer because the remaining neurons in the other regions now have already
become dedicated to processing certain kinds of nonlinguistic experiences
● William Greenough et al. contend that neurons in human and other mammalian brains
exhibit two different kinds of plasticity
● Some neurons are sensitive to experience-expectant information
● As a result of a long evolutionary process, these neurons begin to grow and
differentiate rapidly at about the time they can be expected to receive the kinds
of stimulation important to their functioning
● Other neurons are sensitive to experience dependent information
● Many opportunities for learning occur at unpredictable times during
development, each person learns different and unique things, even into old
age
● Distinctive perceptual features forming the image of a neighbor or the
attributes defining the concept of democracy are unique representations
registered within an individuals neural system
● This is a form of plasticity that implicates neural differentiation as a critical aspect of
brain functioning throughout a person’s lifetime
● “Neurons that fire together, wire together”
