Do not forget the glia

There seems to be growing displeasure with the current plans for ‘big science’ in the area of neuroscience. It is true that if enough data is collected and it is stored and manipulated well, then it can produce understanding of a system. That was the idea behind the human genome project and although it did not produce the answers expected, it did produce, and is still producing, a great deal of understanding. A ‘big science’ effort did find the higgs boson. But just data by itself does not give understanding. I have posted on this before (here).




There is a recent comment in Nature on this subject: RD Fields, Map the other brain, Nature Sept 2013 (here). Field’s message is that we are not looking at the real unknowns of the brain in these big projects – the glial cells. This reminds me of the old saying, “if all you have is a hammer, everything looks like a nail”. Tools for examining the activity of glia are far less developed than those used to examine neurons. Would we not be better off to spend money on developing tools to study glia than to collect massive information on the connectome? He makes good sense.




I believe that exploring neural networks and developing techniques with which to do so are important goals that should be vigorously supported. But simply scaling up current efforts to chart neural connections is unlikely to deliver the promised benefits — which include understanding perception, consciousness, how the brain produces memories, and the development of treatments for diseases such as epilepsy, depression and schizophrenia.”


In any major mapping expedition, the first priority should be to survey the uncharted regions. Our understanding of one half of the brain (the part comprised of astrocytes, oligodendrocytes and microglia) lags a century behind our knowledge of neurons. I believe that answers to questions about the brain and public support for a large-scale study are more likely to come from expanding the search into this unknown territory. As a first step, tools such as optogenetic methods and mathematical models are needed to assess the number, distribution and properties of different kinds of glial cell in different brain regions, and to identify how glia communicate with each other and with neurons, and what developmental and physiological factors affect this. This exploration into the ‘other brain’ must be done together with the proposed studies of neurons. It cannot be achieved as a by-product of them.”




There has been an example in plain view. “The 302 neurons and 7,000 connections that make up the nervous system of the roundworm Caenorhabditis elegans were mapped in the 1970s and 80s. More than two decades later, little is understood about how the worm’s nervous system produces complex behaviours.” In other words the connectome does not result in automatic understanding even in an extremely simple example.




This again seems part of a pattern. The connectome is a sort of ‘wiring diagram’ and if we think of the brain as a sort of conventional computer, the wiring diagram is very valuable to understanding the circuits. As long as we have this computer hangup, there seems not place or role for glia. So way more than half of the brain’s cells are just ignored in an expensive ‘big science’ project.




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