A lot of biology is observation, looking at subject matter using one technique or other. New techniques and equipment such as specialised microscopes like the new microscope at the University of Otago’s Centre for Neuroendocrinology are critical for progress in biology.
A photo essay at Technology Review surveys some of the techniques used to visualise neurons (nerve cells) over the last 100 years, ranging from pen drawings of silver-nitrate stained neurons viewed under a light microscope (top image) through to diffusion tensor imaging (lower image).
Diffusion tensor imaging (DTI) records the movement of water molecules within neurons, using these to reconstruct a three-dimensional image of the neuronal system on a computer. Another article on Technology Review gives some background on this. Water diffuses throughout our bodies, but within axons–the long thin “bodies” of neurons–they tend to diffuse along the length of the axon (the myelin sheaths covering axons traps water within the axon). DTI exploits this property to map axons within a patient’s brain.
There are other excellent photo essays on the Technology Review website, look for the thumbnail images below the essay I’ve pointed to above. One of my favourites is the 1960s-era MIT science fiction society. Count the heavy black spectacles! (Also note the sign in the background in the fifth photograph and the posters on the wall of the first photograph.)
I sense most of my sciblings are making the most of the excellent weather this weekend! I confess my latest posts are “lighter” with the same aim in mind…
Many years ago, after my undergraduate degree, I interviewed to join a research group to write software for imaging blood vessels. Seeing these images reminds me of a different path I might have taken.
I may be able to write a slightly more detailed overview of how DTI works if readers are interested. The explanations I’ve seen on the WWW are either too simple to convey the reality or too complex to be easily read if you don’t know the mathematical terms. This is too lazy a weekend for me to be doing this weekend…
For scientists or students, or those that are very keen, there is a free e-book introducing DTI on-line (7.2Mb PDF file).