Chapter Five: Brain, Motor skill, and Physical Development
The Developing Brain:
Brainstem and the midbrain are involved in basic reflexes and sensory processing as well
as digestion, elimination and respiration.
These functions are all fairly well established at birth
The cortex is the part of the brain that is most closely linked to sensation, motor
responses, thinking, planning and problem solving.
These processes develop well after birth
The frontal cortex is the region of the brain most directly involved in higher levels of
cognition and tends to be the latest to mature.
Neurons are cells that carry electrochemical messages within various regions of the brain.
Neuronal changes include proliferation, migration and differentiation
Proliferation is the production of new nerve cells. Production begins near the end
of the prenatal development right after the closing of the neural tube. Production
is completed by the sixth month of prenatal development. 20,000 neurons are
formed every minute.
Migration is when neurons move from the neural tube to other locations. Inside-
out patterns of development where layers of nerve cell nearer the outer surfaces
are younger than layers deeper in the cortex.
o Glial cells provide a scaffold or radial organization for neuron migration.
Ten times more glial cells form than neurons and make up half the
volume of the brain. They instruct neurons to form synapses with other
Myelin is the sheath of fatty acid that surrounds the axon of many
neurons. Serves to insulate and speed neural impulses up to one
hundred times faster than when it is absent. Glial cells provide the
material from which myelin forms.
o Teratogens such as mercury and alcohol are known to interfere with the
onset and path of neuron migration
Differentiation occurs postnatally. It is the process involved in the enlarging of
the neurons, forming dendrites, branching projections that establish synapses
with other neurons, and the beginning functioning of many neurons.
Differentiation contributes to the substantial increase in the size of the brain
during the first four years after birth. Experience plays a pivotal role in
strengthening connections among neurons.
o Synaptic pruning is the process by which weaker or less active dendrites
of neurons are eliminated The immature brain displays substantial plasticity, the ability to for alternate regions of
the cerebral cortex to take on specialized sensory, linguistic and other information
Experience-expectant information, neurons begin to grow and differentiate
rapidly at the time they are expected to receive kinds of stimulation important to
Experience-dependent information, implicated neural differentiation as a critical
aspect of brain functioning
Glutamate is one of the several factors involved in communication among
Brain development in adolescents:
Show greater activation of the prefrontal region than children or adults
Brain functioning becomes more