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Chapter 5 Study Guide- Development and Plasticity of Brain
Process in the development of neurons:
Profilaration: Production of new cells. Similar among vertebrates, except for the number
of cell divisions (higher in humans compared to chimpanzees).
Migration: After cells have differentiated in neurons or glia they move. Different in
speed- some reach targets until adulthood. Moreover, some chemicals guide neuron
- Immunoglobins - Chemokines
Deficit: Related to reduced brain size, impaired migration and others. Excesses: some
cases of schizophrenia.
Differentiation: process of forming dendrites and axons of neurons.
Myelination: process by which glia produce the insulating fatty acid sheets that
accelerates transmission in vertebrate axons.
- Continues for decades
- Sequence: spinal cord, hindbrain, midbrain, forebrain.
Synaptogenesis: final stage. Formation of synapses. Begins before birth, but continues
New Neurons Later in Life
Cajal claims an adult vertebrate brain cannot generate new neurons (only until
embryological or early infancy), however, there’re exception:
- Olfactory receptors and stem cells.
- Songbirds (area in brain necessary for singing)
- Mammals (adult hippocampus).
A growing axon follows a path of cell-surface molecules, attracted by some chemicals
and repelled by others, in a process that steers the axon in correct direction. Axons sort
themselves over the surface of their targets area by following a gradient chemical.
Competition among Axons as a General principle