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Chapter 13

PSYB65H3 Chapter Notes - Chapter 13: Marasmus, Teratology, Cerebral Atrophy

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Ted Petit

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Chapter 13: Neural Development and Developmental Disorders
Neural Development
Early Development
Neural plate forms from the ectoderm of the embryo
oNeural plate is a patch of cells that are on the dorsal surface of the embryo and eventually becomes
the nervous system
oCells of dorsal ectoderm are stem cells that are pluripotent (can develop into different types of
nervous system cells)
oNeural plate forms groove and forms neural tube
oCells of neural tube rapidly dividing called proliferation
Bumps eventually form parts of the brain of the CNS
oComplete failure of the closure of the neural tube is fatal
oSpina bifida and anencephaly result from partial closure of the neural tube
oAnencephaly occurs when the rostral part of the neutral plate does not fuse
Generally fatal
50% more neurons are produced in the developing brain than are required in the adult brain
oNeural death is apoptotic, or planned, programmed cell death
Controlled by genes
Postnatal Development
Plastic change is the ability of the CNS to alter itself in response to environmental stimuli
oCritical periods of plastic change in which the environment can have a maximal effect on the CNS
Duration and timing of this vary by species
Longer-lived animals (eg. humans) exhibit prolonged critical periods that often occur
later in life
Experience-expectant plastic changes – those CNS changes that are dependent on
experience(s) during the critical period for specific synapses to develop as they should
Much of the sensory cortex appears to have these
If an organism does not experience sensory stimulation during the critical period, long-
lasting impairments in the sensory modality occur
Sensory impairments that occur after the critical period often have limited
effects on the cortex
oExperience-dependent plastic changes – idiosyncratic experiences that occur during critical
periods that also affect brain development
oSynaptogenesis and dendritic branching occur both prenatally and postnally and are presumably
maximal during critical periods
Plastic change required for learning extend well into adulthood
Neurotrophins play critical roles
Parietal Lobe Development
Parietal lobe has inconsistent levels of development at birth
Williams syndrome
oMild to moderate cognitive impairments
oSmaller brain volumes
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