CFD 1450 Chapter Notes - Chapter 12: Functional Magnetic Resonance Imaging, Synaptic Pruning, Cerebral Cortex
CHAPTER 5 OUTLINE
I. BODY GROWTH (pp. 159–161)
A. Changes in Body Size and Muscle–Fat Makeup (pp. 159–160)
1. Birth weight doubles by 5 months of age, triples by 1 year, and quadruples by 2
years.
2. The early rise in body fat peaks at about 9 months. During the second year, most
toddlers slim down.
3. Muscle tissue increases slowly during infancy and does not peak until
adolescence.
B. Changes in Body Proportions (p. 161)
1. Growth of the head and chest occurs before that of the trunk and legs, following
the cephalocaudal trend.
2. Following the proximodistal trend, the arms and legs grow ahead of the hands
and feet.
C. Individual and Group Differences (p. 161)
1. In infancy, sex differences and ethnic differences in body size are apparent.
2. The best estimate of a child’s physical maturity is skeletal age, a measure of bone
development.
II. BRAIN DEVELOPMENT (pp. 161–171)
A. Development of Neurons (pp. 161–163)
1. The human brain contains 100 to 200 billion neurons. Between them are
synapses—tiny gaps where fibers from different neurons come close together but
do not touch.
2. Neurons send messages to one another by releasing chemicals called
neurotransmitters, which cross the synapse.
3. Neurons that are stimulated by input from the surrounding environment continue
to establish new synapses; those that are seldom stimulated soon lose their
synapses, in a process called synaptic pruning.
4. About half the brain’s volume is made up of glial cells, which are responsible for
myelination, the coating of neural fibers with myelin, which improves the
efficiency of message transfer.
5. After neurons and synapses are overproduced, cell death and synaptic pruning
sculpt away excess building material to form the mature brain.
B. Measures of Brain Functioning (pp. 163–164)
1. An electroencephalogram (EEG) detects changes in electrical activity in the
cerebral cortex.
2. Event-related potentials (ERPs) are used to study responsiveness to stimuli and
atypical brain functioning.
3. Neuroimaging techniques, such as functional magnetic resonance imaging (fMRI)
and positron emission tomography (PET), provide precise information about
which brain regions are specialized for certain capacities.
4. In near-infrared spectroscopy (NIRS), infrared light is beamed at regions of the
cerebral cortex to measure blood flow and oxygen metabolism while the child
attends to a stimulus.
C. Development of the Cerebral Cortex (pp. 164–167)
1. The cerebral cortex, which surrounds the rest of the brain, accounts for 85
percent of the brain’s weight and contains the greatest number of neurons and
synapses.
2. Regions of the Cortex
a. The order in which cortical regions develop corresponds to the order in which
