Beyond the Temples of Science

Sven Dierig and Dennis Meyhoff Brink

"All great discoveries are made outside the temples of science."
Carl Ludwig Schleich 1922

An early representation of a neural network. It depicts only neurons; glial cells are ignored. From Exner 1894, p. 39.

In the late 1840s, the pathologist Rudolf Virchow recognized that most of the cells in the brain could be categorized into two distinct groups: nerve cells, and a far more numerous group of cells that surround the nerve cells and fill the spaces between them. Virchow called this second category of brain cells the neuroglia (literally 'nerve glue'). Half a century later, Heinrich W. G. von Waldeyer, a professor of anatomy, published a programmatic synopsis concluding that nerve cells do not constitute a continuous network: instead, the nervous system is composed of discrete individual nerve cells separated from each other by narrow gaps. To mark the difference to the conception of nerve cells associated with Virchow, Waldeyer called these anatomically autonomous units of the nervous system "neurons" (Waldeyer 1891, pp. 1-64).

In 1894 the physiologist Sigmund Exner declared, that any mental state was the result of an antagonism of exciting and inhibiting forces in the network of "neurons" described by Waldeyer. Based on this perspective, everything else in the brain was relegated to the role of functionally passive material filling in the meshes of the neural network. Exner hardly commented on the tissue of the neuroglia, and when he did, he described it as a "supporting substance" (Exner 1894, p. 7). To Wilhelm Wundt, the best known psycho-physiologist at that time, it was simply "glue-giving material" (Wundt 1893, vol. 1, p. 40).