Brain Plasticity: changing your mind

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Brain Plasticity changing your mind
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A New Idea..
Evidence for brain plasticity is relatively recent
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Rebuilt My Journey Back to the Hearing Worldby
Michael Chorost
No one reading this book can fail to be
impressed by the power of neural plasticity, the
brain's capacity to adapt as in this case, to
take a brand new language of sensory input and
turn it into something meaningful.
Review by Jackie Leach Scully, Ph.D
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Highlights

• Brain plasticity is now an accepted feature of
  brain function
• How does experience change the brain?
• Model of learning at the level of the cell
• Evidence that different experiences alter
  structure of brain and behavioral outcome

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Highlights

• Brain plasticity is now an accepted feature of
  brain function
• How does experience change the brain?
• Model of learning at the level of the cell
• Evidence that different experiences alter
  structure of brain and behavioral outcome

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How do experiences alter brain?
Donald Hebb (1949)
Learning via the strengthening of existing
synapses
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Hebbs model of how synapses are strengthened
Before learning
After learning
?
COLBY
Lafayette
Electrical potential
Electrical potential

• Metabolic change
• Structural change

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A laboratory model of Hebbs synapse
Bliss Lømo, 1973
Long-term potentiation in the hippocampus
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A laboratory model of Hebbs synapse
Long-term potentiation in the hippocampus
record
stimulate
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Synaptic plasticity
Learning via the strengthening of existing
synapses Postulated Hebbian synapse
Before learning
After learning
Lafayette
Electrical potential
Electrical potential
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Synaptic plasticity
Learning via the strengthening of existing
synapses Postulated Hebbian synapse
Before learning
After learning
or
Lafayette
Electrical potential
Electrical potential
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Experiences modify synapses

• Hebbs theory about how learning changes
  synapses
• Bliss Lomos empirical model of how learning
  changes synapses

"To learn is to change. Education is a process
that changes the learner."                      
                                 George Leonard 
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Highlights

• Brain plasticity is now an accepted feature of
  brain function
• How does experience change the brain?
• Model of learning at the level of the cell
• Evidence that different experiences alter
  structure of brain and behavioral outcome

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Enrichment Studies
Impoverished
Standard
Bennett, Diamond, Krech, Rosenzweig 1960s
Enriched
Looked at animals living under a variety of lab
conditions
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Measurable changes in brain as a function of
living environment

• Cortex size and weight
• Brain neurochemistry
• Cell body size

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Some resistance.
growth just of bigger and better synapses that
are already there, not growth of new connections
John Eccles, 1965
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Measurable changes in brain as a function of
living environment

• Cortex size and weight
• Brain neurochemistry
• Cell body size
• Structure of neurons
• More synapses

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Measurable changes in brain as a function of
living environment

• Cortex size and weight
• Brain neurochemistry
• Cell body size
• Structure of neurons
• More synapses
• More new neurons!

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More resistance
Read my lips NO NEW NEURONS!
Not a single cell with the physical
characteristics of a neuron born after infancy
was observed in the brain of any adult animal
Pasko Rakic The New Yorker 2001
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Adult brains make new neurons
Rat Hippocampus
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Measurable changes in brain as a function of
living environment

• Cortex size and weight
• Brain neurochemistry
• Cell body size
• Structure of neurons
• More synapses
• More new neurons

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Environmental enrichment enhances learning
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Experiences change brain and behavior
Experience
Brain
Behavior
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Highlights

• Brain plasticity is now an accepted feature of
  brain function
• How does experience change the brain?
• Model of learning at the level of the cell
• Evidence that different experiences alter
  structure of brain and behavioral outcome
• Individual differences in adult plasticity arise
  from experiences during development

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Not all brains are created equal
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Early experiences can have a profound effect on
the developing organism, leading to different
long-term outcomes for brain and behavior
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Experiences change brain and behavior
Experience
Brain
Behavior
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Experiences can also change how brain and
behavior interact
Experience
Brain
Behavior