The Connectome: TED Talk Summary of Sebastian Seung

Here are my notes from the TED talk of Dr. Sebastian Seung from MIT.   I recommend viewing the presentation--although about 17 minutes long it is entertaining as well as showing some great graphics of the imaging and technology

• Your genome--your entire sequence of your DNA
• Small differences in genome make us who we are
• Are we more than our genes?  I would like to think so.
• Well what am I then?   I am my connectome

• C elegant was the worm that had the first mapping of all neuron connections
• But human brain has 100 billion neurons--many connections between these neurons
• Maybe our personal memories are coded in the connections

• I propose this hypothesis:  I am my connectome--my pattern of connections between neurons

• How do we find connectomes in the human brain?
• Technology provides some advances in understanding these connections
• Thin slices of mouse brain can be imaged in three dimensions
• A three dimensional model allows for imaging synapses--connections between neurons
• Neurotransmitters provide the chemical message connections

• How do we move from one synapse to looking for connectomes?
• One key challenge--who do the brains of men and women differ?
• Our brains are like spaghetti--each piece touches many other pieces
• The complexity of these connections make some feel the task is impossible
• It is easy to despair at the difficulty of the task

• Some day a fleet of microscopes will be able to see all the neuron connections 
• Some day supercomputers will use these images to see an entire connection
• I am working on a small piece of this challenge

• Our connectomes change over time as we age and develop
• Synapses are created and eliminated
• Neurons are created and eliminated
• What causes these changes?  
• Some is programmed by your genome but other changes are due to environmental experiences
• Even genetically identical twins have difference experiences and therefore different connectomes

• Here is a metaphor for the connectome: Neural activity is the water of a stream--the connections determine the pathway of this stream
• A connectome is like the bed of a stream guiding the water of the stream
• However, over time the stream of water changes the river bed
• Neural activity is the basis of thoughts, feeling and perception
• Neural activity is the stream and the connectome is the river bed

• Memories may be chains of connections in neurons
• The sequence may guide specific memories, i.e. memory of a piano sonata

• Total length of wires in the brain--I estimate millions of miles, all packed in your brain
• In truth, we can't see the brain in enough detail to see wiring abnormalities in disease such as autism and anorexia

• Our research has philosophical implications
• Death is the loss of your individual neuronal connections: your connectome
• I propose we attempt to find a connectome in a person who has died (and had brain frozen) to see if it may be still intact and provide re-creation of an individual

• This voyage of self-discovery is not just for scientists but for all of us.

In a 2009 Neuron paper (direct link) is a more technical summary of some of the research advances in this topic.  He notes that key technique advances have included:

• fluorescent protein labeling to mark active synapses
• coupling electron microscopy with serial sectioning techniques
• automated cutting and processing of brain slices
• computer-assisted methods to speed up image analysis

Despite these advances, significant challenges remain for advancement of this field of neuroscience

Seung Lab at MIT

Seung on Twitter: @Sebastian Seung

Seung HS (2009). Reading the book of memory: sparse sampling versus dense mapping of connectomes. Neuron, 62 (1), 17-29 PMID: 19376064