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Chapter 5

PSY100H1 Chapter Notes - Chapter 5: Neuroglia, Brain Size, Myelin


Department
Psychology
Course Code
PSY100H1
Professor
Connie Boudens
Chapter
5

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PSYB20 Chapter 5 CHILD’S GROWTH
pages 156-167
BRAIN DEVELOPMENT IN FANCY
-At birth, 1/4 size of mature brain. 6 months, half. 2 years, 75%
-Cerebrum: Two connected hemisphere; largest part of brain.
Embodies shared attributes of animals & uniquely human attributes
-Cerebral Cortex: Covering layer of human cerebrum
Contains 90% of brain’s cell bodies
Specific function > Specific cortex
NEURONS AND SYNAPSES
-Neurons: 100-200 billion at birth, most already present at 7 months gestation
-Neuron proliferation: When neurons multiply at rapid rate during embryonic stage
-Brain cells can be regenerated
-Brain size increase as neurons & connections increase
-Glial cells: provide structural support, regulate nutrients, and repair neural tissue
Some glial cells responsible for Myelination
Covering parts of neurons with fatty wrapping (myelin), makes it easier to
transmit information
Mostly occur during first 2 years but some continues into adulthood
-Neural Migration: movement of neurons within the brain that ensures all brain areas have
sufficient number of neural connections
Absence of sufficient neurons associated with mental disabilities and disorders
-Synapses: Specialized sites of intercellular communication where info is exchanged
between nerve cells, usually by means of chemical neurotransmitters, from axons to
dendrites.
Crucial for learning and survival
Grows by creating new synapses after receiving input from the environment,
allowing for more complicated and sophisticated communications
-Synaptogenesis: forming of synapses.
Begins early in life and continues to adulthood.
-Not all neurons & synapses are necessary or functions through life
Two processes that regulates this:
a) Neuronal Death: (programmed cell death) to provide space for crucial loco of info
transmission
b) Synaptic Pruning: brain’s disposal of axons& dendrites of not so stimulated neurons
frees up space for new synaptic connections
Goal of both is to increase speed, efficiency, and complexity of transmission and to

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form new synapses as new experiences are encountered
-By adulthood: 1 trillion neurons making 100-1000 connection = 1 quadrillion synapses.
SEQUENTIAL DEVELOPMENT OF BRAIN
-There is an orderly sequence to brain development during infancy
2 months: motor reflex drop out, motor cortex begins to oversee voluntary
movements
Similar processes occur in vision, olfaction, and audition.
HEMISPHERE SPECIALIZAITION – begins early in life
-Two hemispheres, both anatomically and functionally different, connected by corpus
callosum.
-One side of the brain can take over the functions of the other side (plasticity)
-Lateralization: specialization of each hemisphere in specific perceptual & cognitive tasks.
-RIGHT
-Functions -Effects when damaged
-Visual special information
-Non-speech sound recognition
-Face perception
-Emotion processing
-Activated in expression of emotions
associated with withdraw to external
environment (distress, disgust, fear)
-Difficulty in attending to visual-
spatial perception tasks
-Spatial disorientation
-Difficulty in facial perception and
expression
-Trouble producing emotional tone of
utterance
-Trouble understanding emotional
state base on speech
-Difficulty in processing auditory and
musical pitches
-LEFT
-Functions -Effects when damaged
-Language processing
-Activated in expression of
emotions associated with approach to
external environment (joy, interest,
-Have trouble understanding content
of speech
-Trouble speaking clearly

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anger)
-Right side of the brain takes over language functions of people who are deaf and uses sign
language (plasticity)
Evidence that the brain can adapt to external influences
Consequences of Brain Lateralization
-Infants whose left hemisphere differentiates among speech sounds and whose right
hemisphere differentiates among non-speech sounds exhibit better language skills at age
three than infants who do not show such strong lateralization
However, responses to hearing speech and matching it to objects are
multidimensional and involve a multitude of processes.
That is to say the brain’s complicated. Why? Cause why the fuck not.
-Lateralization underlies dyslexia 5-10%: American population
Difficulties in integrating visual and auditory information
Some suggest this arises due to abnormal lateralization patterns (Both sides instead
of just R side)
Left hemisphere becomes loaded leading to deficit in language skills.
-Handedness
Most infants show preference for right hand
Suggests handedness develops in the womb
People who are ambidextrous (use both hands) may have less lateralized brains.
BRAIN’S PLASTICITY: EXPERIENCE AND BRAIN’S DEVELOPMENT
-Environment plays a role in brain development
-Plasticity
Capacity of the brain, particularly in its developmental stages, to respond and adapt
to input from the external environment
-2 types of experience influence brain development
a) Normal expected experiences (e.g. visual stimulus)
Trigger synaptic development and pruning
Critical for normal brain development
When interfered, basic abilities are impaired
b) Unique experiences encountered in particular families, communities and cultures
Respond by developing synaptic connection that encode specific and unique
experiences
-Size, structure and biochemistry can all be modifies by experience
Enriched environment increase neural complexity (measure by no. of dendrites)
More dendrites= more synapses= more information transportation
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