Central Nervous System Development
CHELSEA A. IENNARELLA
ANS 536 – PERINATOLOGY
SPRING 2014
ANS 536 - Perinatology - CNS Development
Overview:
 Prenatal CNS
Development
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Period of the Ovum
Period of the Embryo
Period of the Fetus
 Post-Natal CNS
Development
 Male vs. Female Brain
ANS 536 - Perinatology - CNS Development
Lecture 03/26/2014:
 Epigenetic Changes
 CNS Abnormalities
 Species Differences in
CNS Development and
Physiology
Prenatal Growth & Development:
 Period of the Ovum:
 fertilization through implantation
 Period of the Embryo:
 gastrulation through establishment of all major organ systems
 Period of the Fetus:
 maturation of organ systems through birth
ANS 536 - Perinatology - CNS Development
Period of the Ovum:
ANS 536 - Perinatology - CNS Development
Period of the Ovum:
 From the time of fertilization until implantation
(GW 0-1).
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Little or no increase in weight of embryo.
Characterized by reductive cell divisions; hyperplasia.
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Period of the Embryo:
ANS 536 - Perinatology - CNS Development
Period of the Embryo:
 From gastrulation through the establishment of all
major organ systems (GW 2-15).
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Formation of specific organs and tissues occurs.
All major structures and organ systems are established; heart
and circulatory system can be considered functional.
Growth mostly resulting from hyperplasia.
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Human Development Video:
http://www.youtube.com/watch?v=UgT5rUQ9EmQ
ANS 536 - Perinatology - CNS Development
CNS Development:
 CNS development begins during the 3rd gestational
week in humans.
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Most rapid CNS development occurs during the 24th
gestational week.
Brain is not fully developed until adulthood (early 20’s).
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Neurulation:
transformation of the neural plate into the neural tube
ANS 536 - Perinatology - CNS Development
Neural Tube Formation:
 neural plate: a thickened
plate of ectoderm that
gives rise to the neural
tube and crests
 notochord: flexible rod-
shaped structure, derived
from the mesoderm, that
supports the primitive
axis of the embryo
ANS 536 - Perinatology - CNS Development
Neural Tube Formation:
 neural crest: transient,
multipotent, migratory
cell population
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ANS 536 - Perinatology - CNS Development
Cells contribute to many
different systems
including peripheral
nervous systems, skin,
skeletal, adrenal glands,
and GI tract
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Period of the Fetus:
ANS 536 - Perinatology - CNS Development
Period of the Fetus:
 From maturation of organ systems through birth
(GW 16-38).
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Characterized by a large increase in weight and large increase
in nutrient demand.
Growth is mostly resulting from hypertrophy.
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
 prosencephalon: forebrain
 mesencephalon: midbrain
 rhombencephalon: hindbrain
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
 telencephalon:
mature cerebrum
 diencephalon:
thalamus,
hypothalamus,
pituitary
 mesencephalon:
midbrain
 metencephalon:
pons and the
cerebellum
 myelencephalon:
medulla oblongata
ANS 536 - Perinatology - CNS Development
Development of the Embryonic Brain:
http://www.youtube.com/watch?v=mMDPP-Wy3sI
ANS 536 - Perinatology - CNS Development
Post-Natal CNS Development
ANS 536 - Perinatology - CNS Development
Post-Natal Brain Development:
 Infant’s brain is roughly 25% of its adult size at birth.
 75% developed by one year of age
 80-90% developed by three years of age
 Full maturation does not occur until adulthood in
humans (roughly 20-25 years old).
ANS 536 - Perinatology - CNS Development
Developmental Structures of
Importance
ANS 536 - Perinatology - CNS Development
Limbic System:
 Collection of several structures located in
the inner brain beneath the cortex.
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prefrontal cortex
hypothalamus
amygdala
hippocampus
ANS 536 - Perinatology - CNS Development
Prefrontal Cortex:
 Location of most
advanced cognitive
function

Attention, motivation,
goal-directed behavior
 Last area of the brain to
mature
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Undergoes important
developmental changes
even into adolescence
ANS 536 - Perinatology - CNS Development
Hypothalamus:
 Regulation of stress
response by signaling the
pituitary to secrete ACTH
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stimulates secretion of
stress hormone, cortisol,
from adrenal cortex
stimulates secretion of
adrenaline from the
adrenal medulla
ANS 536 - Perinatology - CNS Development
Amygdala:
 Evaluates threats and
triggers the body’s
response to stress

Allows for generation of
learned emotional
responses to a variety of
situations
ANS 536 - Perinatology - CNS Development
Hippocampus:
 Memory formation and
spatial learning.
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Declarative memory; the
memory of facts or events
Important in recognition
ANS 536 - Perinatology - CNS Development
Synapses & Neurons:
 The brain processes information by forming
networks of neurons.

Communicate using electrical and chemical signals.
 Messages are passed between neurons at
connections called synapses.
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Synaptic Pruning:
 For first three years of life, a child’s brain has
roughly twice as many synapses and an adult.
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Synapses used frequently become stronger.
Synapses rarely used are more likely to be eliminated.
ANS 536 - Perinatology - CNS Development
Brain Development Video:
http://www.youtube.com/watch?v=mMDPP-Wy3sI
ANS 536 - Perinatology - CNS Development
Continued Brain Development:
 During the second year of life, the brain’s language
center develops more synapses and becomes more
interconnected
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Vocabulary often quadrupled during this time.
 Rapid increase in rate of myelination.
 Emotional awareness and self awareness develop.
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Pinky & the Brain:
 Nature vs. Nurture
 Genes lay foundation for brain but final wiring is caused by an
environmental effect
 Laboratory mice are virtually genetically identical.
 Dramatic difference seen in IQ
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Differences Between Male &
Female Developing Brain
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Differences During Embryonic Development:
 Differences seen as early as GW 26
 Thickening of CC in females that remained post birth
 Males outperformed females on motor and spatial
cognitive tasks; females were faster in tasks of
emotion identification and nonverbal reasoning
(Satterthwaite et al. 2014)
ANS 536 - Perinatology - CNS Development
ANS 536 - Perinatology - CNS Development
Overview:
 CNS development begins in utero and continues into
adulthood.
 Several transient structures undergo morphological
and functional changes to give rise to a more mature
system.
 Interaction between genetics and environment
determine final CNS capacity and functionality.
ANS 536 - Perinatology - CNS Development
Next Lecture:
 Epigenetic Changes Effecting the CNS
 CNS Abnormalities
 Species Differences in CNS Development and
Physiology
ANS 536 - Perinatology - CNS Development
Questions:
ANS 536 - Perinatology - CNS Development