The Technological Singularity

by Murray Shanahan

Suppose that we can genetically engineer the mouse so that every neuron in its brain contains a sequence embedded in its DNA that is unique to that neuron, a kind of “DNA barcode.” Then, with every neuron individually barcoded, the mouse’s brain could be “infected” with an otherwise harmless virus that has been specially engineered to carry genetic material across synaptic gaps, enabling DNA from the pre-synaptic neuron to recombine with DNA from the post-synaptic neuron. This would produce new strands of DNA, each containing a pair of barcodes representing the existence of a synaptic connection between the two neurons in question. The brain of the mouse would thus become a repository of billions of genetically encoded records of pairwise connections between neurons. The task then would be to extract these data, which could be done using DNA sequencing technology. With this method, a neuron-level connectome would be obtainable without the costly intermediate step, in terms of data and computation, of submicron-scale imaging and image processing. Moreover the bottleneck with this method, the speed and cost of DNA sequencing, has undergone years of exponential improvement in the aftermath of the human genome project.