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 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