Chapter 7

Chapter 7 - Chapter 7: Life-Span Development of the Brain...

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Chapter 7: Life-Span Development of the Brain and Behavior I. Growth and Development of the Brain Are Orderly Processes a. The brain emerges from the neural tube i. Within a week, emerges the human embryo 1. Ectoderm – outer layer ii. Neuro groove – groove between the neural folds in a developing embroyo. iii. Neural tube – the tops of the neural ridges come together to form this. iv. At the anterior part of the neural tube form 3 subdivisions: forebrain (prosencephalon consisting of telencephalon and diencephalon), the midbrain (mesencephalong) and the hindbrain (rhombencephalon, consisting of the metenceophalon and the myelencephalon). v. Interior of the neural tube becomes the fluid filled cerebral ventricles of the brain, the central canal becomes the spinal cord vi. Embryo – first 10 weeks after fertilization vii. Fetus – after 10 weeks. II. Development of the Nervous System Can be Divided into Six Distinct Stages a. 1) Neurogenesis – the mitotic division of noneuronal cells to produce neurons b. 2) Cell migration – the massive movements of nerve cells or their precursors to establish distinct nerve cell populations (nuclei in the CNS, layers of the cerebral cortex, etc. c. 3) Differentiation of cells into distinctive types of neurons or glial cells d. 4) Synaptogenesis – the establishment of synaptic connections as axons and dendrites grow e. 5) Neuronal cell death – the selective death of many nerve cells f. 6) Synapse rearrangement – the loss of some synapses and development of others, to refine synaptic connections. III. 6 Stages in Depth a. Cell proliferation produces cells that become neurons or glial cells i. Neurogenesis – the production of nerve cells ii. Cells divide (mitosis) and form a closely pack layer or cells called the ventricular zone. All neurons and glial cells are derived form cells that originate from the ventricular mitosis. iii. Eventually some cells leave the ventricular zone and begin transforming into either a neuron or a glial cell iv. The hallmark of vertebrae development is that cells sort themselves out via cell-cell interaction, taking fates that are appropriate in the context of what neighboring cells are doing. Thus, vertebrae development is less hardwired and more susceptible to being shaped by environmental signals and experience. b. New nerve cells migrate i. The cells that form in the ventricular layer though mitotic division move away in a process known as cell migration . ii. Cells in the developing brain move along the radial glial cells , which extend from the inner to the outer surfaces of the emerging nervous system. They act as a series of guide wires, and the newly formed cells creep along them. Some may move in a direction perpendicular to the radial glial cells or move in a rostral steam.
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iii. Failure in cell migration ay lead to reduced population of neurons behavioral disorders. iv. Molecules that promote the adhesion of developing elements of the NS,
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This note was uploaded on 02/12/2010 for the course PSYCH 115 taught by Professor Shaine during the Winter '07 term at UCLA.

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Chapter 7 - Chapter 7: Life-Span Development of the Brain...

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