Brain Development
I. Growth & development of new cells
1. proliferation: the productions of neurons
during early development
2. migration: some neurons must move to their
eventual location
3. differentiation: the distinctive parts
(e.g., axons) of the neuron develop
4. myelination: myelin develops on some axons
5. synaptogenesis:
formation of synapses
II. Neural survival
1. many neurons develop (more than you need)
only necessary ones survive
2. finding appropriate targets is important
for neuron survival
A. target cells release neurotrophins:
chemicals that promote neuron survival & growth
a. e.g., nerve growth factor promotes survival
of presynaptic cells
B. apoptosis: dying of cells without targets
III. How do axons find their targets after injury
1. some cells release chemicals that attract
certain axons & repel others
2. many synapses may develop but only the
most appropriate ones survive
3. Schwann cells form a tube for axons to grow in the PNS
IV. Experience is important
1. enriched versus impoverished environment in
rats
2. more educated humans have more widely
branched dendrites
V. Is brain size correlated with IQ scores in humans?
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Brain & Human Nature Outlines