Re: A section of rat brain
OK, let's be a bit less gnomic, and try to place Henry and the rest of Blue Brains' work into an IT context.
A cortical microcircuit is really the minimal functional unit of a brain. An analogy is to consider a neuron as a transistor and the microcircuit as some sort of generic IC. One of the achievements of this work is to provide us with a provisional count for the number of distinct neuron (i.e. transistor) types. When you consider that biology has what we'd call an "extremely high process variation" and that neuroscientists are basically given a pile of 37,000 different cells and asked to classify them into "morphologies" then you're getting an idea of what's needed.
Another key idea in this paper is that the places where connections are made occur geometrically, that is wherever the "wires" get sufficiently close to permit connections (synapses) to form. Obviously, it remains for the results to be confirmed by other labs, but if this result proves true, then again our task becomes a bit easier, as the biology becomes a bit less tentative.
To me, as someone tasked with providing an even more simplified version of this circuit (but running in real time, rather than taking hours to simulate a second, as the model reported in the original article does) the true significance is that we have a "reference semantics" against which we can compare the behaviour of the SpiNNaker model.
A test version of SpiNNaker-2 has been taped out in July, and we should get back the result just before Christmas. Although the test chip is just trying out ideas (in 28nm), our[*] aim is to permit a microcortical circuit of 40,000-100,000 neurons[**] to be realised on a single one Watt chip.
There are of course any number of features which Henry's model does not yet include, but the intriguing thing is that the model already makes a number of predictions about the results of future experiments.
[*] Sebastian Hoppner (TUD), Christian Mayr (TUD), Steve Furber (UMAN), Dave Lester (UMAN).
[**] Both the number of neurons and the number of connections increases as the animal's brain complexity increases, e.g. for a macaque we're looking at about 80,000 neurons with a fan-in/out of ~5,000. For the rat we're looking at 37,000 neurons with a fan-in/out of ~1,000.