A First Post and the First Image of Brain Tissue under the Microscope

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It is not easy to write a first post. So, as a first post I thought I’d share another first.

As far as I know, this image below is the first published image of ‘brain’ tissue under the microscope. (I hope Mo Costandi corrects me if I am wrong.) It is really picture of the nerve that connects the eye to the brain, still nervous tissue. The image was published in 1675 by Mr Antonie van Leeuwenhoek. [1]

Wellcome Library, London under Creative Commons by-nc 2.0 UK: England & Wales

What I find fascinating about this image is how it reminds me of how it all started. Most of what I do studying neuroscience involves using microscopes, and this image reminds me how far along we’ve come. I can’t but wonder what went through Leeuwenhoek’s mind when he saw this image – after all he did not know what we know now. In fact, even what light was at the time was not what we know now, so interpreting what that image of the optic nerve meant for visual neuroscience must have been quite an interesting challenge.

I can’t help but chuckle when I read in his manuscript this passage:

“I here thought to myself whether every one of these hollownesses might not have been a filament in the Nerve and besides, that twas needless, there should be a cavity in the Optic Nerve through which the Animal Spirits, representing the species or images in the Eye, might pass into the brain.”

I chuckle, because I am amused by his reference to ‘Animal Spirits’. But I can’t but try to imagine what that first observation might have looked like to someone who saw it for the first time, and without the experience that even the average biology student has. I often wish I could get one of those old microscopes and repeat his experiments and see what nervous tissue might have looked like at that time to understand why people thought of the brain the way they did. Microscopy was such a new thing that even a century after that image was produced a word of caution was expressed in Home’s Croonian lecture (1799) [2]

“It is scarcely necessary to mention that parts of an animal body are not fitted by being examined by glasses of a great magnifying power, and, whenever they are shewn one hundred times larger than their natural size, no dependence can be placed upon their appearance.”

It would take some time for microscopes and the methods to process tissues to get better so that we could make more sense of what we were looking at under the lens, and so it is not surprising that it was not until the end of the 19th century that the ‘cellular theory’ that was contemporary to Leeuwenhoek’s observation was accepted to be true for the brain as well.

After all, how much detail we know about anything in biology is only as good as the precision of the instruments we use to study them. I can’t help but wonder what Leewenhoek would think of the microscopic images of nerve tissue that we produce today. We have come a long way, and gained a lot of precision. And after all, that is the way that science moves on.

A few years back I came across this snippet by George Brecht at the Walker Art Center in Mineapolis, Minnesotta

“Excercise
Determine the limits of an object or event
Determine the limits more precisely
Repeat,
Until further precision is impossible”

I couldn’t help thinking how well this artist described the process of science. We keep hitting the limits of the precision we can measure stuff with, and have to wait until a new tool is developed to measure the same thing a little bit better. Sometimes, we confirm what we thought previously, on occasion we find something unexpected and are forced to change our minds about what we hold true. It is the hope of hitting that unexpected that gets me out of bed every morning to go to the lab.

[1] Mr. Leewenhoeck Microscopical Observations of Mr. Leewenhoeck, Concerning the Optic Nerve, Communicated to the Publisher in Dutch, and by Him Made English. Phil. Trans. January 1, 1675 10 378-380; doi:10.1098/rstl.1675.0032 (pdf)

[2] Everard Home The Croonian Lecture. Experiments and Observations upon the Structure of Nerves. By Everard Home, Esq. F. R. S.Phil. Trans. R. Soc. Lond. January 1, 1799 89 1-12; doi:10.1098/rstl.1799.0002 (pdf)

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