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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