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Chapter 4

PSYC 208 Chapter Notes - Chapter 4: Synaptic Pruning, Primitive Reflexes, Synaptogenesis

6 pages103 viewsFall 2012

Course Code
PSYC 208
Maria Weatherby

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Chapter 4 - Independent Questions
I. Physical Changes
A. The Brain and Nervous System
1. (a) Is the reproductive system fully formed at birth?
-Yes, but it doesn’t grow or change much until puberty.
(b) What brain structures are the most developed at birth? Identify the functions of these
-Brain and nervous systems develop rapidly during the first 2 years.
-At birth, the midbrain and the medulla are the most fully developed.
-These two parts regulate vital functions such as heartbeat and respiration, as well as,
attention, sleeping, waking, elimination, and movement of the head and the neck.
(c) What part of the brain is the least developed at birth? Identify the functions of this
-The cortex; it is convoluted grey matter that wraps around the midbrain and is involved
in perception, body movement, thinking, and language.
Synaptic Development
2. (a) Define the term synaptogenesis, which occurs due to growth of both dendrites and axons.
-synaptogenesis – process of synapse development
(b) Define the term synaptic pruning, which occurs because each synaptic growth spurt
generates many more synapses than we actually need.
-synaptic pruning process by which unused or unnecessary neural pathways and
connections are eliminated
(c) Overtime, the cycle of synaptogenesis followed by synaptic pruning leads to a more
efficient brain. What is the cost or downside of increased efficiency of the brain?
-Downside because infants have more unused synapses than adults, they can bounce
back from a host of insults to the brain much more easily than an adult
(d) Define the term neuroplasticity.
-the ability of the brain to reorganize brain structures in response to experience
(e) Your textbook states that one of the implications from the cyclical synaptogenesis-
pruning feature of neurological development is that brain development follows the old
dictum “Use it or lose it”. Why do we lose brain functions we don’t use? (NO
-We need more forms of stimulation to keep brain function. For example, a child growing
up in a rich or intellectually challenging environment will retain a more complex
network of synapses than one growing up with fewer forms of stimulation. Brains of
infants possess grater neuroplasticity than those of older children and adults.
3. (a) Define the term myelinization.
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-Process in neuronal development in which sheaths made out of a substance called myelin
gradually cover individual axons and electrically insulate them from one another to
improve the conductivity of the nerve
(b) Although synaptic pruning (ACTIVITY DEPENDENT) is influenced by whether or not
our synapses are considered necessary or useful (whether we use the synapse), what
influences which neural pathways are myelinized first?
-The sequence of myelinization follows both cephalocaudal and proximodistal patterns.
4. (a) What brain structure
primarily regulates the skill of attention?
-Reticular formation
(b) When does myelinization of the reticular formation begin and when is it complete? –
-It begins in infancy and continues to spurt out across childhood and adolescence. The
process isn’t complete until a person is in her mid-20s.
B. Reflexes and Behavioural States
Reflexes (I will expand on this section in the chapter 4 lecture template on adaptive reflexes)
5. (a) What adaptive reflex disappears in infancy or childhood?
-Automatically sucking any object that enters the mouth
(b) What adaptive reflexes persist across the lifespan?
-Withdrawal from a painful stimulus and the opening and closing of the pupil of the eye
in response to variations of brightness
(c) Compare the purpose of adaptive reflexes to the purpose of primitive reflexes.
-Adaptive reflexes are to help humans survive while the purpose of primitive reflexes is
unclear and is controlled by less sophisticated parts of the brain
(d) Identify Philip Zelazo’s research finding about encouraging infants to exercise their
stepping reflex.
-found that infants who were encouraged to exercise the stepping reflex were more likely
to spontaneously display the stepping movements and began walking at an earlier age
Behavioural States
6. (a) How does Bronfenbrenner’s macrosystem context influence the way North American
and European parents respond to their infants’ sleep patterns/problems?
-North American parents typically see a newborn’s erratic sleep cycle as a behaviour
problem that requires “fixing” through parental intervention. Parents focus a great deal of
attention on trying to force babies to sleep through the night
-European parents are more likely to regard newborns’ patterns of sleeping as a
demonstration of normal development and tend to expect babies to acquire stable
sleeping patterns naturally without parental intervention, during the 1st 2 years
(b) You hear a mother give her daughter some parenting advice: “Don’t pick up your crying
baby too quickly because it is good to let your baby cry a little first”. Does research support
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