Quote: Walter Gilbert predicting personal genomics

I'm catching up on my reading this weekend. Right now I'm getting through Misha Angrist's "Here Is A Human Being" and getting increasingly jealous for every page. Angrist had his genome sequenced as a part of the Personal Genome Project, something I wouldn't mind having done myself.

I found this lovely 1992 quote from Walter Gilbert in the book. The number of bases of the human genome was pretty accurate even back in the early nineties.

Three billion bases of DNA sequence can be put on a single compact disc and one will be able to pull a CD out of one's pocket and say, "Here is a human being; it's me!"

This year marks the first decade since the "full" (more or less) sequence of the human genome was announced. But the advancements (and nightmarish visions) many expected still form an alluring horizon. One day, I want to be able to get my genome sequence out and say "Here I am; it's me!" Some people see all kinds of problems with personal genomics, but I can hardly wait for the day.

Happy Darwin Day! Mockingbirds and Darwin's original thought

It's Darwin day! The anniversary of the old man's birthday (202nd this year) and a great opportunity to dig up some piece of Darwiniana and celebrate evolution!


Hood mockingbird, endemic to Española island, Galapagos. Ref: Wikimedia Commons.

Darwin's Galapagos finches and their differing beaks (see image here) are often credited as the original inspiration for Darwin's theory of evolution through natural selection. It's true that he brought many specimens of finches back from the Galapagos, and that they subsequently received a lot of attention in his scientific work and in "On the Origin of Species", but what many people don't know is that it was in fact a different group of birds that inspired the original thought: Mockingbirds, or Tencas in Spanish. Thanks to the wonders of the Internet, all of Darwin's writings are available online and we can go looking in his notebooks for this original thought in his own handwriting.

Oxytocin taking off

Since I posted my two entries on the oxytocin/ethnocentrism link last week - part 1, part 2 - they have really taken off and gotten more attention than my very modest blog is used to. The first one has been linked on economist Tyler Cowen's blog Marginal Revolution, which generated a surge of over 3000 visitors over the following few days, on BigThink.com - "Hormones Are Not Deterministic" and it's even been translated into Spanish by Eduardo of the blog La revolución naturalista - "Oxitocina, etnocentrismo y determinismo hormonal", with an interesting discussion following in the comments. Both posts were also recently linked by Daniel Lende of the blog Neuroanthropology with the words "It’s always great to discover an exciting new blog!" Right back at you! His post linking me is also currently featured on the front page of PLoS Blogs.

The two entries have also been tweeted a few times, notably by Bora Zivkovic (@BoraZ) of A Blog Around The Clock, @CulturalNeuro and Maria Popova (@brainpicker) of BrainPickings.org.

I've also gotten a bunch of new Twitter followers in the process, and I'm averaging 200 visitors a day on the blog, which is about 10 times more (I told you it was modest) than before the oxytocin posts. I also seem to notice an increase in the amount of comments on other blog posts as well.

Finally I also wanted to mention a few blog posts that also comment on the oxytocin/ethnocentrism findings that I neglected to mention in my original entries. Ed Yong has a post on Not Exactly Rocket Science that veers a little bit towards the "hormonal determinism" side. He also writes that this finding "makes a degree of evolutionary sense", which I would argue against. On The Frontal Cortex Jonah Lehrer thankfully focuses on oxytocin effects and the complexity of the neurobiological substrates. Both posts are less critical of the original findings by De Dreu and co-workers, which balances my two posts nicely.

Some more history of neuroscience visualized through Google NGrams

This is the second post where I take a look at Google NGram visualizations of the history of neuroscience. If you haven't seen the first one, you probably should before continuing to read this one.

In my previous post I completely ignored a large number of the cells in the brain: glial cells! It's often said they outnumber neurons by a ratio of 10:1, a truth that is still open for modification, but at the very least in some brain regions they are just as many as the neurons. Let's plot some different general terms for these cells against the terms "neurons", "nerve cells" and "nerve fibres" as references. In plural just because I've already plotted the singular forms in the previous post.



We can see that mentions of "neuroglia" go back to roughly the same period as "nerve cells" and "nerve fibres", some 2-3 decades before "neurons". Around this time "neuroglia" was a general term referring to the "connective tissue" of the nervous system, according to the OED, as opposed to the fibres which were considered the actual nervous tissue. The word neuroglia literally means "cement of the nerves". Nowadays it's known that they have so many other functions than providing support and nutrients for neurons, including very important modulations of signaling in the brain.

The use of simply "glia" starts taking off around the same time as "neuron", showing the co-incidence of the neuron doctrine and the characterization of the actual cells that made up this previously so vague "connective tissue". To find the first use of "glial cells", which is quite a common term nowadays, we have to fast forward to the 1940's and 50's. If you take a look at this following NGram there's some indication that both the plural "glial cells" and the singular "glial cell" are more commonly used than "neuroglia", but the differences are not very big.



In my previous NGram post I plotted the more general terms "neurology, "neuroscience" and "neurobiology" against each other, but what if we add as many sub-fields of neuroscience and neurobiology as we can come up with to see it it's possible to see how the field has diversified and developed? I include "neurology" as well for reference.



I notice a couple of really interesting things instantly. First of all, "neurology" does seem to be the oldest term by far, and many of the more specialized terms seem to predate "neuroscience" and "neurobiology" as well (see the first post). I propose that the diversification of the field seems to have happened in three "bursts" (arrows) during the 20th century! "Neuropathology" seems to be quite old, but together with "neurophysiology", "neurosurgery" and "neuroanatomy" it forms a cluster that starts going up during the 1930's. The second burst was during the mid 1950's to mid 1960's when "neurochemistry", neuropharmacology, "neuroendocrinology" and "neuropsychology" start going up (the latter two practically overlap). Sort of associated in time to this cluster is "neurolinguistics", that for some reason strikes me as a true child of the 70's.

The last burst is perhaps less certain, but we see the marked increase in the use of "neuroimaging" during the 1980's, showing the awesome technological development of the late 1900's. "Cognitive neuroscience" also forms part of this later burst and seems to be intimately associated with the rise of neuroimaging technologies. The NGram viewer wouldn't allow me to add more terms, but in this ngram you can see that "neuroethology" has a small little bump around the same time.

It's remarkable how you can really read the development of the field, from an early focus on the "mechanics" and "physics" of the nervous system to a subsequent discovery of the chemistry of the brain, when else but in the 60's!, and a progressive realization that it affects our cognition and behaviors, paired with technological advances.

What are then the terms of the future? What are the neuro-terms on the rise? After doing several experiments, I came up with these: "neuroethics", "neurotechnology", "neuromarketing", "neuroeconomics" and "neurotheology".



"Neurotechnology" is not surprising. But perhaps what we're seeing here more than anything are the growing attempts to reconcile or explain questions of morality, spirituality and philosophy with neuroscience as well as a growing obsession with the cognitive and neurobiological processes behind money-making/spending. Seems like a weird and wonderful future.

How to be a (good) neuroscientist

Having written recently about falsehoods associated with the hormone oxytocin, and having taught about neuroimaging today, I find myself inspired by a couple of recent posts from the scientific blogosphere that expose falsehoods about the brain's activity and functional magnetic resonance imaging (fMRI).

Over at his blog Oscillatory Thoughts, neuroscientist Bradley Voytek reminds us how we should properly interpret neuroimaging studies to avoid making false claims about "where" in the brain different functions, such as behaviors and mental abilities, are localized: How to be a neuroscientist.

The interpretation of these localization results is confounded, however, by a lack of clarity in what is meant for a "function" to be localized. For example, Young and colleagues (2000) noted that for a given function to be localizable that function "must be capable of being considered both structurally and functionally discrete"; a property that the brain is incapable of assuming due to the intricate, large-scale neuronal interconnectivity.

This is sort of one level higher to what I argued in my first oxytocin post. Just as there is no one gene for any particular property, or indeed no one hormone for any particular property; a particular function is not localized to any particular region of the brain, even though neuroimaging studies sometimes give that impression. Voytek identifies two important principles to go by.

- Behaviors or mental abilities are not discrete/particular definable entities and cannot be "dissected out" and isolated from the whole gamut of behaviors and abilities. I argued the same thing in my second oxytocin post.
- Different regions of the brain interact and interplay, giving feedback to each other and cooperating in very complex ways to produce the brain's functions. Therefore it's unlikely that one particular function, however defined, is localized in any one region of the brain.

Elsewhere Audrey Lustig lists 4 things to keep in mind when you're reading about fMRI:

- Brain pictures of regions "lighting up" (see image below) are often misleading.
- Some fMRI studies are good, some are bad.
- fMRI images don't show what's happening in the brain in real time.
- Neuroscientists can't "read your mind".

Both posts are worth a read!


The religious brain compared to the nonreligious brain... see reference here.

Brain imaging studies that study function, especially fMRI, are task dependent and show brain activity during a specific task, subtracting the brain activity from a control state. This means that other brain regions that aren't shown "lighting up" in the brain pictures are active as well during the task, only that they were also active during the control. fMRI reveals differences between one state and the other and if the researchers are not careful about the statistical analysis of their data, they could end up showing the equivalent of brain activity in a dead salmon (original dead salmon fMRI paper).

If you want to see an example of an fMRI study done right, go no longer than to Neuroskeptic and read about Imaging the Brain Better, Faster, Thinner.

A brief history of neuroscience in Google NGrams

In the days and weeks following the release of Google's NGram Viewer I got completely addicted and started plotting everything between heaven and earth, just like everyone else. The scientific merits of Google's NGram Viewer have been discussed over and again, especially the term "culturomics", and some of its inherent errors have been revealed, and some fixed. These discussions notwithstanding, I'm amazed at the course of events that actually can be visualized and analyzed in this way. Just take a look at these NGrams applied to the history of neuroscience. Click on the images to see the original graphs on the Google NGram Viewer.

To start out, let's see if we can trace the origin of the field's object of study, the neuron. I've included the two accepted spellings "neuron and "neurone" as well as "nerve cell" and "nerve fibre".*



We see that the last decades of the 19th century were absolutely decisive in the history of neuroscience. What we're really seeing is the emergence of the neuron doctrine; the idea that the nervous system is made up by discrete but interconnected cellular components, or neurons. This revolution was made possible by the works of Santiago Ramón y Cajal and Camillo Golgi (among others, but these two were the heavy hitters and received the Nobel prize in 1906), and the anatomist Heinrich Waldeyer-Hartz was the first to formally propose the doctrine in 1891. Do you see how clearly the use of "neuron" practically started around 1891? Incredible!

The fact that there are two spellings, with or without a terminal e, is a cool curiosity. We can see how the use of "neurone" sinks after the 1930's, but the two alternative variants really competed there. The use of "nerve cell" and "nerve fibre" seem to predate both of them, but their origin is definitely after 1850 and they don't rise in the same way as the 20th century comes along.

The name "Waldeyer" also has a peak before 1890. Names are always tricky, but what if we include the general prefix "neuro" in the analysis together with "Waldeyer", "nerve cell" and "nerve fibre"?



The field was clearly developing in the decades before the neuron doctrine in the 1890's, and Waldeyer seems to have been prominent in that development. We see that the use of neuro-related terms has an upward slope that follows Waldeyer's almost exactly. Waldeyer was a very prominent general anatomist and histologist of the time, so if we add the term "histology" to the analysis we can probably confirm the incredible development that lead to the emergence of modern neuroscience: the ability to chemically stain tissues and individual cells in preparation for the study under the microscope.



Much of this development seems to have had it's start in the 1850's.

Next I want to find out when the collective terms for the field like "neurology, "neuroscience" and "neurobiology" came up. Let's add those to the general "neuro"-prefix and "neuron" as references.



Although the foundations of modern neuroscience and neurobiology were laid in the late 19th century, the terms themselves don't show up until well into the 20th century! "Neurology" seems to be a much older term, perhaps indicating that the arrangement and disease states of the nervous system were under study well before the underlying mechanisms were understood. Or maybe that it used to be a more general term? It's an interesting question. According to the Oxford English Dictionary "neurology" goes back to 1681 meaning something like "systematic arrangement of nerves".

There are some more interesting experiments one could do, but this is enough for now.

*) Including "nerve" doesn't add anything useful since it's such a common word. According to the OED it goes back to the 1400's, originally meaning sinew or tendon.

Oxytocin, ethnocentrism and evolution (pt. 2)

>> Go here for part 1.

I didn't want to risk making my previous post too long, and I wanted to keep it focused on "hormonal determinism", so I set aside a whole branch of my commentary on the link between the hormone oxytocin and ethnocentrism for another post. The findings I comment on were presented by De Dreu and co-workers in the latest edition of PNAS (see reference below).

So, today I want to talk briefly about bad evolutionary arguments.