Brainy names

This is just a mini post to pass the time before I get around to writing the next one..

Here are a couple of links to two really cool posts on the Neuroskeptic blog, definitely my favourite blog and one which anybody with an interest in neuroscience and psychology should know about.

Post 1

Post 2

The posts contain cross sections of the human brain with different structures labelled with their scientific (usually latin, sometimes greek) names alongside the literal translations of those names- "etymological maps" of the brain. This prevalence of Latin names for brain structures is a hangover from the tradition beginning centuries ago that in some cases even stretched to the beginning of the 20th century where Latin was the accepted language for medical terminology. Consequently, to the unititated learning about brain anatomy can be quite intimidating or worse still people might completely switch off when they're met with a wall of unintelligible jargon.

What I like about these posts is that they show that there isn't anything intrinsically complex about this terminology and actually the names are often pretty unimaginative and literal, meaning that the translations can end up sounding pretty ridiculous. To take an example from the first of the neuroskeptic posts, lingual gyrus means tongue gyrus (gyrus is itself a Latin term given to the bumpy parts of the cortex) and as you might imagine it bears some resemblance to a tongue, although like spotting shapes in clouds the resemblance isn't quite 100% and requires a bit of imagination to see.

I am quite an etymology geek and so I already have a couple of favourite brain regions based on the etymology of their names. Neither are particularly absurd but I like them because whilst the names were given by early anatomists based purely on what they saw they actually hint at important functional properties of neurons in the structures, they are the substantia nigra and the locus coeruleus. 

Substantia nigra literally means "black substance" because by eye it is almost black and stands out clearly from the surrounding regions. It gets its dark colouration from neuromelanin, a substance which is abundant in the dopamine releasing neurons present in the substantia nigra, one of the two major sources of dopamine neurons in the brain along with the ventral regimental area. Neuromelanin is synthesised along the same pathway of chemical reactions which the cell uses to produce dopamine. It accumulates in these neurons and carries out functions of its own which probably involve protecting the neuron from damage and deteriaration.

The Locus Coeruleus on the other hand is the main source of noradrenaline (or norepinephrine if you prefer) releasing neurons in the brain and the name means "blue place" or "blue spot". Again this is due to its colouration under anatomical examination, oddly though the blue colour seems to also be caused by neuromelanin in the noradrenaline cells of the nuclei. I'm guessing a difference in the number or density of neuromelanin containing neurons in the two nuclei is what causes the black and dark blue appearance but if anyone knows for sure please enlighten me in the comments.

My favourite from the two Neuroskeptic posts is a good illustration of why it was probably quite sensible for anatomists to stick to what they saw and not start naming based on what they guessed the function was. Pituitary gland literally means slime gland and the reason for this name is because it was originally believed that the pituitary gland secreted mucus destined for the nasal passages. So now it's just stuck with this name that is completely unrelated to its function or appearance.

It could all have been so different and a whole lot more boring if we only started naming structures more recently. When you look at the technology the earliest neuroscientists had available to them its no wonder the brain structures ended up with the names they did. Although Luigi Galvani was first showing the effects of electricity on the nervous system in the last decade of the 18th century it wasn't until the early to mid-20th century that our understanding of neurons and the technology was advanced enough for neuroscientists to listen in on the activity of the brain in animals and other humans, this meant that apart from studying patients with brain damage they had no good way to assign particular functions to brain regions. It was also not until the early to mid-20th century that biochemical techniques became available to determine the chemical or protein profile of cells to understand how they might function. This meant that early anatomists were mostly stuck with saying what they saw.

But as technology has caught up some of the old names have fallen out of favour in preference for newer, more functionally relevant names. For example the striate cortex, the striate cortex is a region in the occipital lobe of the cortex which roughly corresponds to the functionally defined primary visual cortex (or V1). The region got its original name because it has a line which runs in parallel to the outer edge of the cortex called the line for Gennari, this line is formed by the huge numbers of axons carrying visual information from the lateral geniculate nucleus and terminating in this region. This line gives that region a striated appearance hence the name*. Now that the striate cortex is known to be the first processing point of visual information in the cortex when it is discussed in papers and textbooks it is almost always concerning that function, as such you never really hear striate cortex anymore and instead it's almost universally referred to as the primary visual cortex or V1 for short.

Anyway, that was a slightly longer then anticipated post. But hopefully some of my interest in etymology of neuroscience words will have rubbed off on you (if it has this webpage will probably be of interest) and hopefully you'll also go and check out the Neuroskeptic blog because that is definitely worthwhile if you haven't already. 

* To understand what this means look at the external link on this wiki entry about the line of Gennari (I would have put a picture on the post but I couldn't find a decent picture that I was entirely certain was available for public re-use!)