Download Development of the Brain

Chapter 5
Development and Plasticity
of the Brain
Development of the Brain
• Plasticity
• Nature versus Nurture
• Rapid development
Fig. 5-1, p. 122
Fig. 5-2, p. 123
Development of the Brain.
• The human central nervous system begins to
form when the embryo is approximately 2
weeks old.
Fig. 5-3, p. 123
Development of the Brain
• The fluid-filled cavity becomes the central
canal of the spinal cord and the four
ventricles of the brain.
Development of the Brain
• At birth, the human brain weighs
approximately 350 grams.
• By the first year. the brain weighs
approximately 1000 grams.
• The adult brain weighs 1200-1400 grams.
Development of the Brain
•
The development of neurons in the brain
involves the following four processes:
1. Proliferation
2. Differentiation
3. Myelination
4. Synaptogenesis
Fig. 5-6, p. 127
Development of the Brain
•
Neurogenesis??
•
Sperry’s (1954) research
Fig. 5-7, p. 127
Development of the Brain
• Neural Darwinism
• Neurotropin
• Apoptosis
• Nerve growth factor (NGF)
Development of the Brain
• Fetal alcohol syndrome
• Cocaine abuse
• Enriched versus impoverished environments
Fig. 5-10, p. 131
Fig. 5-11, p. 132
Fig. 5-12, p. 133
Plasticity After Brain Damage
• Survivors of brain damage show subtle to
significant behavioral recovery.
• Some of the mechanisms of recovery include
those similar to the mechanisms of brain
development such as the new branching of
axons and dendrites.
Plasticity After Brain Damage
• Possible causes of brain damage include:
– Tumors
– infections
– exposure to toxic substances
– degenerative diseases
– closed head injuries.
Fig. 5-13, p. 138
Plasticity After Brain Damage
• A closed head injury
• A stroke or cerebrovascular accident
– Ischemia
– Hemorrhage
– Edema-
How can we help?
• tissue plasminogen activator (tPA)
• Cooling the brain
• Cannabanoids
Fig. 5-14, p. 139
Plasticity After Brain Damage
•
•
•
•
•
Diaschisis
Axonal regrowth
Collateral sprouts
Gangliosides
Progesterone
Fig. 5-16, p. 141
Fig. 5-17, p. 142
Plasticity After Brain Damage
• Ways the brain compensates for decreased
input and to restores normal functioning
include:
• Denervation supersensitivity
• Disuse supersensitivity
Plasticity After Brain Damage
• Phantom limb
• Deafferenated limbs