A HUMAN BRAIN MAP
The plan to write a set of instructions for the human brain takes shape
Understanding the human brain is a monumental task, but that hasn’t stopped neuroscience stepping up to meet the challenge. There’s the Human Brain Project, one of the largest ever EU-funded projects, the $5 billion BRAIN Initiative in the US, and the more recently announced China Brain Project.
One of the aims of the US initiative, launched in 2013, is to map all the neurons in the brain as well as their connections. Starting with the mouse brain, the view is to move towards the same goal in humans. It could “help us crack the code the brain uses to drive behaviour,” says Joshua Gordon, one of the National Institutes of Health (NIH) project directors. But he admits it won’t happen overnight. Take the Human Genome Project for example, a simple map won’t provide all the answers and it may take many years to figure out how the physical features of the brain relate to memories, thoughts, actions and emotions.
For a start, the brain’s ‘code’ can’t be written
in a sequence of letters. According to Gordon, the first step is building a ‘parts list’ composed of different types of neurons and then mapping each of those parts in physical space. Currently, the parts list for mice is well underway, whilst the human equivalent could take another five to ten years. But understanding how these parts produce behaviour is trickier still. “Each of those parts also then has a constellation of functions,” Gordon says. Eventually, there should be enough detail in the map to explain how neurons in certain brain circuits function at a molecular level, to produce specific behaviours.
The technologies being developed along the way will have a wider impact on neuroscience too, including research into a broad spectrum of brain disorders from epilepsy to Parkinson’s. Rapid single-cell sequencing now allows scientists to quickly gather data from hundreds of thousands of individual neurons, highlighting the DNA that is switched on in each one. Meanwhile, imaging tools for studying neurons in exquisite detail and tracking their activities in real-time are advancing.