We are entering the golden age of brain science, at least in terms of funding, if not yet understanding. This year, the European Union and United States announced separate long-term programmes to study the human brain that, together, could pour more than US$2 billion into neuroscience during the next decade (that's more than 2 cents for every neuron in the body's most complex organ). Driving these investments is the sense that researchers are on the verge of making leaps in understanding the brain — advances that could eventually lead to better treatments for mental disorders.

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In this special issue, Nature taps into this excitement with reporting and opinions on efforts to apply current technologies and invent new ones to grasp how all the grey and white matter in the brain actually works.

Take the design of 'neuromorphic' hardware — computer systems that function according to similar principles as neurons and neural circuits in the brain. After years of development, applications in robotics, mobile electronics and neuroprostheses are finally in sight (see page 22). On the biological side, researchers are applying a broad array of techniques to mapping neural connections in the brain (see page 147). On page 31, neurologist Kenneth Kosik argues that technologies that can monitor thousands or millions of networked neurons are exactly what are needed to better understand and treat Alzheimer's disease. Meanwhile, researchers with neuroimaging expertise are increasingly in demand, thanks to hopes that the technology will reveal information about everything from the progression of brain diseases to behaviour (see page 153).

Nature special: New angles on the brain

Amid the excitement, there are also significant questions about the major brain projects (see page 5). In the case of the US initiative, neuroscientists are not sure what kind of research it will support, and many in the field have spent much of the year struggling to define the scope of the project (see page 26). However, everyone agrees that the new opportunities presented by technology warrant exploitation. This message comes through especially vividly on page 29, where an anonymous neuroscientist with Parkinson's disease recounts his poignant experience of studying the brain while watching his own begin to fail.