I am the wrong person to be digging into this, since my neuroscience understanding is at the level of "picture books to be shown to infants." I have read many of the typical pop science books on the subject; also papers to do with brain function vis-a-vis vision, sleep, nociception, fatigue, etc.; but I have little math and no expertise. About the only thing I can do is Google or look in journal databases. Having said that, I did finally find a neuroscientist/blogger's reaction to this latest Blue Brain paper.
The blogger in question is Yojan John, a researcher at the
Neural Systems Laboratory, Department of Health Sciences, Boston University. He describes himself and his research on his Quora profile
here, and his ResearchGate list of publications is https://www.researchgate.net/profile/Yohan_John/contributions; typical titles include "https://www.researchgate.net/publication/310440081_Distinction_of_Neurons_Glia_and_Endothelial_Cells_in_the_Cerebral_Cortex_An_Algorithm_Based_on_Cytological_Features?_iepl%5BviewId%5D=OJkmXBII1ogFow0E0EBvCrJ4&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A310440081&_iepl%5BinteractionType%5D=publicationTitle," Nov. 2016, "https://www.researchgate.net/publication/316157558_Posterior_orbitofrontal_and_anterior_cingulate_pathways_to_the_amygdala_target_inhibitory_and_excitatory_systems_with_opposite_functions?_iepl%5BviewId%5D=mv0E0fItonRayftsCqPPkTI8&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A316157558&_iepl%5BinteractionType%5D=publicationTitle," April 2017, etc. So he seems like someone who potentially could have a meaningful opinion on Blue Brain research.
He maintains (apparently sporadically) a blog called
Neurologism; and on June 21 he offered a brief critique of the "11-dimensional" Blue Brain paper, under the title "
Is there a multi-dimensional universe in the brain? A case study in neurobabble." He says he wrote the critique in response to a question he was asked about the study on Quora.
He starts with the same objection I had to the way the Frontiers press release implies that the "11 dimensions" are somehow spatial in nature:
I was asked a question on Quora about a recent study that talked about high-dimensional ‘structures’ in the brain. It has been receiving an inordinate amount of hype, partly as a result of the journal’s own blog. Their headline reads: ‘Blue Brain Team Discovers a Multi-Dimensional Universe in Brain Networks.’ As if the reference to a ‘universe’ weren’t bad enough, the last author, Henry Markram, says the following: “We found a world that we had never imagined”.
As will soon be clear, using words like ‘universe’ and ‘world’ in conjunction with the word ‘dimension’ creates a false impression that these researchers are dealing with spatial dimensions and/or how the brain represents them. This is simply not the case.
He next moves on to the study. The question he got on Quora was this: "What exactly are the recently discovered multidimensional geometrical objects in the neuronal networks of the brain?" The gist of his answer is as follows; I have snipped a few paragraphs and condensed a few others (removed line endings), as well as bolding the last two sentences:
The authors employ somewhat complex ideas from
graph theory to analyze connectivity among neurons in a small segment of rat neocortex . . . dimension [in the study] just refers to the number of neurons that are connected in an all-to-all network. In the area of rat neocortex they studied, they found that 11-neuron cliques were common.
The word dimension has a variety of meanings in mathematics and science. The idea of spatial dimension is most common: when we refer to 3D movies, this is the kind of dimension we are thinking of. The space we are familiar with has 3 dimensions, which we can think of in terms of X, Y, and Z coordinates, or in terms of up-down, left-right, and front-back directions. The dimension of a network has nothing to do with spatial dimension. Instead, it has more to do with the number of degrees of freedom in a system. In physics, the number of degrees of freedom is the number of independent parameters or quantities that uniquely define a system.
So really, this paper is just talking about the statistics of local neuronal connectivity. They describe their findings as surprising when compared to other statistical models. All this means is that certain connectivity patterns are more common that one might expect under certain ‘random’ models . . .
Outside of the narrow community of computational neuroscientists who use graph theory, these results are interesting but hardly ground-breaking. Moreover, as far as I can tell these findings have no definitive functional implications. (There are some implications for network synchrony, but in my opinion synchrony has itself not been clearly linked with higher-level concepts of function.)
Neural network modelers assume all kinds of connectivity patterns than deviate from pure ‘randomness’, so such findings aren’t particularly surprising. So I am baffled by the hype this research is getting. It strikes me that extremely lazy science journalism has collided with opportunistic PR practices.
Although as I say I know pretty much nothing about neuroscience as such – certainly nothing about the attempts of the Blue Brain folks & others to develop computational simulations of brain function - I would certainly agree with the last sentence above. Basically the Frontiers press release got picked up by many news outlets, the editors/reporters of which (a) probably didn't understand a word in either the press release or the study, and (b) didn't care.
All this may go some way toward answering the quite appropriate question asked by the OP (
@Greg Bernhardt) in his initial post.