Since the 19th century people have speculated that the essence of human identity is stored in the connections between our neurons. Today we have the technology to find out if this is true.
Until now, most of what we know about the brain has been based on observations of what happens when different regions are damaged, or on imaging techniques like functional MRI that show which areas are active but tell you little about how they relate to one another. Not knowing how these different regions interact is like trying to work out how a telephone network works without knowing where all the wires go.
“You’re missing huge amounts of information if you don’t know which regions are connected to other regions,” says Tim Behrens of the University of Oxford, who is a member of the Human Connectome Project. The HCP aims to map the large-scale connections of 1200 human brains and is expected to start delivering the goods in late 2012.
With 100 billion neurons, each with around 10,000 connections, mapping the human brain will be no easy feat, and charting every single connection could take decades. The HCP will tackle the lowest hanging fruit first: charting the major highways between different brain regions, and showing how these connections vary between individuals. To do this they will combine several imaging tools including something called diffusion MRI, which maps the structure of the white matter that insulates the “wires” of the brain, and also resting-state MRI, which measures how brain regions oscillate in unison as a result of shared connections.
Even this should produce a more complex structural anatomy of the brain than anything ever seen before, and provide tantalising insights into how personality, memory and even consciousness are formed.