Neurological Development
Neurobiology of Learning Differences
JHU
Drs. Denckla and Lewis
Agenda
PHASE ONE
The Brain…what’s in it, how does it develop, how
does it work, and what threatens its functions?
PHASE TWO
Learning…what goes into the process as we
progress through school to adulthood?
TBQ…
Why do teachers in 21st century
have to have knowledge of brain
function and dysfunction in order
to competently offer instruction?
PHASE ONE
The Brain
How does it develop?
what does it do?
what is it like?
how does it operate?
Prenatal Development
By 6 – 7 months of 9, 70% of brain cells
are in cerebral cortex
Genetic blueprint for cortex folding similar
but subtly individual
Cellular Migration
Other cells’ axons or glia guide
directions
Chemicals also act as “GPS”
97% of cells go correctly
Getting Connected, Time-
Sensitive
Aggregation by biochemical and receptor
similarities
Sprout axons (outgoing)
Sprout dendrites (incoming)
Preprogrammed targets
Axon + Dendrite=Synapse
Strengthening Connections
Chemotrophic attractants
Stimuli even in utero
Fetus kicks, sucks thumb, increases
motor connections
Fetus hears, increases specific auditory
connections
Pruning overlaps Proliferation
Not much below cerebrum
Half of cortical motor neurons die
Possibly lack of “good” connections
“starves” neurons
Myelination in Last 2 Months
Like insulation of electric wires
Speeds signal transmission
Prenatal: motor & sensory axons
Prolonged postnatal process
Postnatal Shaping of Brain
Networks of synapses activate
By age 3 yrs each neuron connects up to
10k others
“Use it or lose it” begins
But-timely experiences, during critical
periods, yield the best results
Brain Growth 0 to 3 yrs
Few cells added, but existing cells enlarge
and sprout axons & dendrites
Inputs and synapses grow reciprocally
and selectively
Age two is “blooming buzzing confusion,”
the new outruns the pruning of the old
Boy Brain or Girl Brain?
From 20 week fetus to puberty, girls 20%
faster developers
Interhemispheric connections at 3 levels,
larger in women
Paradox of Preschool Learning
Not much episodic (personal history)
memory before 3-4
Cause is lack of hippocampus connectivity to
cortex
Lots learned procedurally
Language is somewhat special still,
somewhat mysterious
School-Age Brain
Right hemisphere is ahead of left (and girls
20% ahead)
Most of school is left-based
Long cerebral pathways myelinate within
large range (e.g. 3 to 10 yrs “normal”)
Connecting R and L: late bloomers?
Adolescent Brain
Hormones increase synaptic pruning
Hormones stir up emotional brain
Amygdala enlarges
Frontal lobe connections myelinate
If timing is off, impulsivity wins!
Attention/correction matures via anterior
cingulate gyrus
Corpus callosum myelinates
What do we know about the brain?
The environment influences
how the brain develops
The brain changes with every
experience we have and in
early years is necessary for
development
Second languages and music
are learned more efficiently
in the first decade of life
What do we know about the brain?
Brain development is
integrated – not one
system then another
Critical periods in
development allow
optimal learning
Learning is strongly
influenced by emotion
Brain chemistry effects
mood, personality and
behavior
Lateral View of the Brain
Frontal Lobes –
site of executive Parietal Lobes – site of
functions of the orientation, calculation
brain and some recognition skills
Occipital Lobes –
Temporal Lobes – Site of visual
site of sound,speech processing skills
and some memory skills.
Midline View of the Brain
Limbic system – center of emotional & reasoned responses
Thalamus – receptor of sensory input (not smell)
and direction to other parts of the brain for processing.
Amygdala – sensory
center of rage, fear
and pleasure
Hippocampus – converts information
from working memory to long term
memory
Midline View of the Brain
Corpus Callosum – “cable” of
the brain; serves as a bridge
between the hemispheres
Cerebellum –
“little brain”, monitors
impulses and coordinates
physical responses; has
important role in learning,
timing, and performing
Frontal cortex – monitors higher motor tasks
order thinking, problem solving,
regulates excesses in reactions
Visual Pathway of the Brain
Objects are perceived
and the thalamus sends The visual cortex is a
the perceived image primary area of response
to the correct processing and that response is
center of the brain – in then connected to other
this case to the occipital processing areas, such as
lobe (location of the the memory center.
visual cortex)
via the optic nerve.
The right side of Damage in the
the perceived image visual cortex may
is transmitted to the cause a failure in
left occipital cortex transmission of the
and the opposite perceived message.
occurs on the left. One’s eyes may be
fine, and yet one
may not “see”.
Auditory Pathway of the Brain
Broca’s area relates
to processing oral Objects are perceived and
language in initiation the thalamus sends the
or response. perceived message to the
correct processing center
of the brain – in this case,
the temporal lobe, for
discrimination.
Wernicke’s area relates
to the processing of
incoming auditory language
for understanding.
Neurotransmitters
The brain’s chemical signals
are well known to
researchers, and are known
as neurotransmitters.
Neurotransmitters are either
excitatory or inhibitive,
meaning they control the
increase or decrease of
neuronal activity.
Among the most commonly
known are acetylcholine,
dopamine, seratonin, and the
endorphins.
Neurotransmitters (selected)
AMINES PEPTIDES
ACETYLCHOLINE CORTISOL
controls movement & emitted in “fight or flight”
memory response
ADRENALINE (EPINEPHRINE) too much= deteriorates
other areas
puts body in a state of alert
ENDORPHINS
DOPAMINE suppress pain sensation
enhances pleasurable
feelings VASOPRESSIN
NOREPINEPHRINE related to control of blood
pressure
too much= manic responses
too little= depressed
responses
SERATONIN
oldest neurotransmitter
relates to sleep
Synapses and Neurotransmitters
The juncture of the axon of one
neuron and that of another is
called a synapse.
The regulatory or electrical signal
from the axon stimulates the
release of the neurotransmitter
into the synaptic cleft, the tiny
space between the neurons,
which converts into a chemical
signal.
Once received into the next
neuron, the chemical signal
converts back to an electrical
signal, which is sent down the
dendrite spine to trigger a
reaction.
Language areas
Broca’s Area controls the
expression of vocabulary,
syntax and grammar; it is
about the size of a quarter
and is located at the left
temple region
Wernicke’s Area is the gateway to the
comprehension of language as it is
presented to the listener/reader; it is
about the size of a silver dollar and
is located above the left ear
Parietal area associates “meaning”
Integration of Systems
The successful
integration of all
areas of the brain,
including the
chemical systems,
results in
successful
movement,
memory and
permits new
learning.
Mirror Neurons/Social Learning
Newborns (42 minutes old) match orofacial
movements shown to them, “share representations
for self and others”
Closely linked to language acquisition
Shared neural circuitry for perception and production
6 month old infants listening to speech activate both
Wernicke’s and Broca’s
Your students may come to school
with any of these conditions
seizures or epilepsy attention deficits
traumatic brain injury learning disabilities
psychiatric illness autism spectrum
disorder
environmental toxins
coordination disorders
genetic disorders
communication
emotional/behavioral disorders
disorders
All of these learning elements are
centered in the brain
Working memory
Long term memory
Receptive language
Expressive language
Attention/Concentration
Organization/Planning
Psychomotor skills
2 kinds of visual
perception
So…what is your answer?
Why do teachers in 21st century
have to have knowledge of brain
function and dysfunction in order
to competently offer instruction?