Arxiv has a paper by Andrew Adamatzky (one of the authors of the nytimes article) called "Are motorways rational from slime mould’s point of view?", from 13 Mar

Arxiv has a paper by Andrew Adamatzky (one of the authors of the nytimes article) called "Are motorways rational from slime mould’s point of view?", from 13 Mar 2012, which has pictures: http://arxiv.org/pdf/1203.2851.pdf http://arxiv.org/pdf/1203.2851.pdf Take a look at page 4.