Scientists have published an atlas of the brain

Lord Rutherford, the discoverer of the atomic nucleus, divided science into physics and stamp collecting. (He was, after all, a physicist.) But he had a point. Other sciences, such as astronomy, chemistry, geology and, most notably, biology, rely a lot on collecting things (not literally, in the case of astronomy) and classifying them in various ways that would delight philatelists. Physics, by contrast, relies on analysing phenomena.

That said, the philatelist branches of science have been pretty successful, biology especially. And this week sees the addition of a new album to biology’s collection, in the form of 21 papers about the brain and its cells. The work was done under the purview of the BRAIN Initiative Cell Census Network, which is organised by the National Institutes of Health, in America. The papers are published in various bits of the American Association for the Advancement of Science’s empire of journals, Science and its spin-offs. They are intended to help answer three, related questions: what and where are a brain’s cellular components; which cells are involved in neurological and psychiatric illnesses; and what makes the brains of Homo sapiens different from those of other animals?

Brains, particularly human ones, are the most complex objects in the known universe. That complexity is emphasised by the fact that, as these papers confirm, they are reckoned (depending on how you define such things) to contain about 3,000 different types of cell. For comparison, it was not so long ago that entire human bodies, brains included, were estimated to be built from just 300 cell types.

The estimate was confirmed by a team of researchers at the Karolinska Institute, in Stockholm, and the Allen Institute for Brain Science, in Seattle. They studied, post mortem, the brains of three men and a woman, taking 606 samples from nine regions of the organ and also one from the spinal cord. They then extracted the nuclei of individual cells and looked at the RNA molecules therein.