Building the Human Brain

The human brain is exceedingly complex and studying it encompasses gathering information across a range of levels, from molecular processes to behavior. The sheer breadth of this undertaking has perhaps led to an increased specialization of brain research and a concomitant fragmentation of our knowledge. A potential solution is to integrate all of this knowledge into a coherent simulation of the brain ( 1 ). However, simply “building” a brain from the bottom up by replicating its parts, connections, and organization fails to capture its essential function—complex behavior ( 2 ). Instead, just as engineers can only construct cars and computers because they know how they work, we will only be able to construct a brain if we know how it works—that is, if we understand the computations that are carried out in individual brain areas, and how these computations are implemented on the level of neural networks. On page 1202 of this issue, Eliasmith et al. ( 3 ) make headway toward this benchmark by presenting just such a large-scale computational model of the human brain that can simulate a variety of complex behaviors.