The ancient Greeks compared human life to a slender thread,
spun, measured, and cut by three goddesses called The Fates.
Today, by all the search for the secrets of human life in a different thread,
that’s slender molecule called DNA, two strands wound in a double helix.
Each strand is composed of small molecules called nucleotides.
which come in four types designated by the letters A, C, G, and T.
Your DNA spells out more than a billion letters
in a sequence that is known as your genome.
Your genome and mine are almost identical
which is why we are more similar to each other than to our dogs or cats.
But our genomes also differ very slightly which is why we look different
and why we are susceptible to different diseases.
It is tempting to think that I am my genome, but that would not be correct.
As you lay in your mother’s womb, you already possessed your entire genome
but not yet, your memory of your first kiss.
Memories and many other aspects of your personal identity
are contained not in your genes but in your brain.
The byzantine shapes of neurons resembled trees with long branches,
extending long branches that entangle tightly
to form an almost impenetrable brain forest.
Millions of miles of branches are packed inside your skull
like wires connecting your 100 billion neurons in a vast network.
Where the branches of two neurons touch
there can be a tiny junction called the synapse,
at which one neuron signals to another.
The two neurons are said to be connected like two friends talking on the telephone.
Your connectome is the totality of your brains connections.
Now, I’d like to propose another theory of personal identity.
I am my connectome.
Alas, this theory is currently untestable,
because our technologies foreseen connectome
are too primitive for anything more than this tiny worm.
In the 1970s and ‘80s a team of scientist
cut a worm salami of 20,000 fantastically thin slides
placing every slice in a powerful microscope.
They captured images of every neuron and every synapse
and compiled this map the worm’s connectome.
Compared to our brains this is miniscule
containing 7000 connections between just 300 neurons.
Yet, finally, it took over a dozen years of tedious manual labor.
Fortunately, the German physicist Winfred Dank?? and other researchers
have invented new technologies that allow the mass production of
terabytes and petabytes of images of neurons and synapses.
This opens the door to finding the connectomes of brains
more similar to our own.
But the torrential flow of data overpowers human comprehension.
That’s why my laboratory at MIT is constructing artificial intelligent
supercomputers to see and analyze the images automatically.
Our activities are part of a futuristic circle whose time has finally come.
The brain creates computers to understand the brain.
In the connectome theory of personal identity, memories play an important rule.
Many neuroscientists believe that your connectome is like a book
in which your memories are written and your brain records new memories
by changing its connections.
We will attempt to test this theory by reading the memories that are
hypothesized to be written in connectomes.
We will begin with the bird connectome trying to guess from it the pattern of
neural activity that is replayed in the bird’s brain
every time it sings its song.
In some mental disorders like Alzheimer’s disease
it’s obvious that many neurons die
but in other disorders there is no apparent brain abnormality.
Perhaps these disorders are due to connectophathies,
miswirings in the brain that are undetectable currently
but will be revealed by the technology of connectomics.
Many years ago I visited the Cathedral of Notre Dame.
I marveled at its complex and beautiful structure
which took almost 150 years to build.
Your brains are far more complex and beautiful than Notre Dame.
They also took decades to build, not from bricks, but from connections.
Someday your brain, like an ancient cathedral, will disintegrate.
The connections will be lost and with them your memories will be lost, too.
But as long as we live, the glorious variety of mental experiences
is based on a staggeringly intricate organization of connections.
The quest for the connectome is the search for the essence
that makes us uniquely human.
Thank you very much.