• 3 pounds of squidgy, whitish,
• 3 times bigger than any ape or
86 billion neurons (fire in patterns)
Each with up to 5000 dendrites
(branches); allows thousands of
synaptic connections in 3d space
WE DO NOT HAVE A CONVINCING
OVERARCHING THEORY FOR HOW
IT WORKS (YET)…
Same the number of neurons as
adults only 20% of adult size!
Very few connections; and
more compactly spaced
Like a ship coming out of the fog
• 4 weeks
• 8 weeks
• 3 months
• 6 months
SYNAPTIC DENSITY PEAKS AT AGE 2
There is a rapid proliferation and
overproduction of synapses during
infancy. Two year olds have an
astonishing 50% more connections
than in adults!
Followed by “synaptic pruning” that
eventually brings the overall number of
connections down to their adult levels.
This process is most exuberant during the
first few years of life, AND extends well
into adolescence and young adulthood.
1. More connections produced than needed
2. Competing for limited nutients and O2
3. Neurons that fire together wire together
4. Use or lose… brain constructs itself by the
logic of evolution and embryology; not
analogous to a manufactured computer
• What if? Living in the subjunctive tense?
• Scientific method: wet-wired… All babies are
• Curiosity/Creativity? All Kids are artists?
• Who do we think we are?
• Living in stories…making it up as we go along
(on the fly)?
1. Embodied and embedded
2. Constructed self (brain) based on experience
Neural Darwinism: connections that “fire
together ‘wet-wire’ together”
3. Neuroscience in its infancy (excited about
new discoveries– especially imaging)
4. Brain is not strictly analagous to a computer.
Do we think who we are?