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Brain and Behavior:
Neurobiology of Everyday Life
HOW DO I
GET TO BE ME?
Miracle of Brain Development
Week #3
Daniel G. Amen, MD
First,
some brain basics
Brain Basics #1
THE BRAIN IS INVOLVED
IN EVERYTHING YOU DO
 How
you...
 Who
you are as a...

think

therapist

feel

child

act

parent

interact

spouse
Brain Basics #2
When your brain
works right, you
work right
When your brain
doesn’t work right,
you can’t work right
Brain Basics #3
BRAIN IS MOST COMPLEX ORGAN
 100
billion neurons, trillion glial cells
 each
neuron connected to many other cells
 1,000,000,000,000,000
 more
 2%
connections in brain
connections than stars in universe
of body’s weight
 Uses
20-30% of the calories consumed
Brain Basics #4
BRAIN IS VERY SOFT
 Brain

is very soft
consistency of soft
butter
 Skull

is really hard
many ridges
Brain Basics #5
TYPICAL NEURON
Brain Basics #6
NERVE CELL PARTS
 Dendrites
= nerve antenna, receivers
 Cell
body = contains nucleus, protein making
machinery, mitochondria (energy makers)
 Axons
= sends signals, action potentials to
other cells, wrapped with myelin to protect
and speed signals along
Brain Basics #7
GRAY VS WHITE MATTER
 Gray
matter = cells bodies
 White
matter = mylenated nerve cell tracks,
connects hemispheres
 Interneurons
 Projection
= local connections
neurons = sends signals to other
parts of brain and body
Brain Basics #7
GRAY VS WHITE MATTER
Brain Basics #7
WHITE TRACTS
Brain Basics #8
TYPICAL SYNAPSE
Brain Basics #9a
NEUROTRANSMITTERS
How the Brain Communicates with Itself
Acetylcholine (ACh) – mostly excitatory
muscle problems, Alzheimer’s, learning
problems
Serotonin (5-HT) – excitatory
depression, OCD, eating disorders, sleep,
pain
Brain Basics #9b
NEUROTRANSMITTERS
Dopamine (DA) – excitatory and inhibitory
Parkinson’s, ADD, addictions, depression,
schizophrenia
Norepinephrine (NE) – excitatory
depression, ADD, anxiety
Epinephrine (E) – excitatory
anxiety
Brain Basics #9c
NEUROTRANSMITTERS
Gamma-aminobutyric acid (GABA) – inhibitory
seizures, bipolar disorder, anxiety, pain
Glutamate – excitatory
most widely available neurotransmitter,
paradoxically both main neurotransmitter for
memory and main one responsible for cell
death
Brain Basics #10
NEUROGENESIS

1990s overturned 100 year old doctrine

Through life BRAIN MAKES NEW
NEURONS

Programmed cell death is important,
BALANCE
 Long
term potentiation
 Learning
and physical exercise encourages
neurogenesis
Brain Basics #11
DEVELOPMENT
 Low
activity at birth
 Ramps
up from 0-3, stays high til 5
 Pruning
starts at 5, levels off at 10 (tracks that
are not used)
 Brain
continues to be active til 40
 Repair
 After
mechanisms less efficient after 40
40, need to encourage health
The Brain Miracle
 Brain
constructed in levels w/different fxns
 Development
influenced by genes,
environment and experience
 Increased
brain complexity increases
behavioral complexity
 Develops
different rates (PFC and teens)
 Children
do not have social skill as adults
Social Development
Stages of Brain Development
1.
2.
3.
4.
Cells birth (neurogenesis, glialgenesis)
Cell migration
Cell differentiation
Cell maturation (dendrite/axon growth)
6.
Synaptogenesis (formation of synapses)
Cell death and synaptic pruning
7.
Myelogenesis (formation of myelin)
5.
Cell Birth
 Cells
lining neural tube, brain’s nursery,
stem cells (capacity for self renewal)
 Cortex
begins development at 7 wks,
mostly complete by 20 weeks

5 mos preme can live outside
 5-9
months a very vulnerable time
(anoxia, toxins – neurogenesis mostly
complete)
Cell Migration
 Cells
migrate along radial glial cells
 Cortex
has 6 layers -- lower layers laid

layers 5-6: output to other brain areas

layer 4: input – sensory

layers 1-3: intergrative functions
Cell Maturation
 Dendrite
arborization (branching)
 Continues
 Axon
after birth, grow slowly
growth, up to 1mm a day (fast
growth)
 Growth
factors involved
 Experience
involved – Hebb’s kitchen rats
Synaptogenesis
 1014 synapses
 Too
many for genes alone to determine
 General guidelines for layout, guided by clues,
signals, hormones and experience
 Simple connections by 5 mos prenatally
 Complex connections by 7 mos
 Increase rapidly after birth
 Visual cortex doubles from 2-4 mos of an
infant
Cell Death & Synaptic Pruning
 Overproduction
of neurons and synapses and
subsequent loss
 42% of synapses die
 Prunes unnecessary/incorrect synapses
 May lose up to 100,000 per second
 “Use it or lose it”
 Experience, opportunity, stress has great
influence
 Programmed cell death -- apoptosis
Myelinization






Myelin wraps/insulates neurons
Increases efficiency of function
Begins after birth
Continues into adulthood
Maturity is associated with areas that
develop last, esp the PFC
Drug abuse/stress can delay development
Influences On The Brain
Biology
Psychology
Social
 Genetics
 Prenatal exposure
 Health
Biological
Influences
 Toxic exposure
 Trauma
 Brain system health
 Hormones and neurotransmitters
Bonding
Stimulation
Self talk
Psychology
Influences
Experiences
Parenting -- New Skills for Frazzled Parents
Support systems
Stresses
Opportunities
Modeling
Effective living
Social
Influences