New project to map gene expression in the human brain

This week scientists from the Allen Institute for Brain Science in Seattle announced a multi-million dollar project to create a map of the human brain revealing the pattern of activity in some 20,000 genes. The four-year project, which builds on the earlier mouse brain map announced in 2006, will give fresh insight into the causes of diseases ranging from autism to spinal cord injuries, potentially helping scientists to develop more targeted treatments.

When complete, the human brain atlas will join the mouse one free online at 'Allen Brain Atlas' - a resource which since its launch has been cited in some 100 scientific papers.

The genome operates by sending instructions from DNA in the form of mRNA (messenger RNA ) for the manufacture of proteins. The mouse brain atlas was made by taking thin slices of tissue from different parts of the brain and then using a technique called 'in situ hybridisation' to label a specific mRNA to show where a gene is being expressed. This was repeated for nearly every gene in the mouse genome. However trying to repeat this effort on the human brain - an organ over 2000 times bigger - will be a very big task, say the researchers.

The mouse brain atlas has already yielded some important findings in the field of neuroscience. For example the atlas has lead to the discovery of two genes, BEX1 and BEX2, implicated in a type of brain cancer called glioma. Similarly, it might be used to find genes important in other diseases, like autism, by comparing the patterns of gene activity in the brains of autistic people.

Being able to compare the patterns of activity in mouse and human brains may also help scientists to work out how the human brain evolved to be so advanced, by allowing them to detecting differences which would normally be invisible. 'We could ask whether our brains simply have more of the same kinds of cells, or if we have fundamentally different types of cells in different arrangements', Allan Jones, the institute's chief scientific officer told science writer Alan Boyle.

Two other projects looking at gene expression in the mouse were also launched simultaneously - one looking at the mouse brain during development from embryo to juvenile and the other at the mouse spinal cord. 'Instead of a 3D atlas, effectively we're going to have a 4D atlas, where we'll be able to watch movies [showing] data-driven models of the brain as it's growing', said Jones.