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How to be a neuroscientist

In this post, I will teach you all how to be proper, skeptical neuroscientists. By the end of this post, not only will you be able to spot "neuro nonsense" statements, but you'll also be able to spot nonsense neuroscience questions.

I implore my journalist friends to take note of what I say in this post.

Much has already been said on the topic of modern neuroimaging masquerading as "new phrenology". A lot of these arguments and conversations are hidden from the lay public, however, so I'm going to expose the dirty neuroscientific underbelly here.

Bradley Voytek Cognitive Neuroscience New Phrenology fMRI

(Image source: The Roots - Phrenology)

This post was prompted by a question over on Quora: What is the neurological basis of curiosity? Where does curiosity reside in the brain?

The question itself is of a type that is commonly asked in cognitive neuroscience: where is <vague behavior> in the brain?

But what does it even mean to ask where "curiosity" is in the brain? What would an answer look like?

According to the article linked to in the current top answer on Quora:

In study after study, scientists have found that the striatum lit up like an inferno of activity when people didn’t know exactly what was going to happen next, when they were on the verge of solving their mystery and hoped to be rewarded—it was more active then, in fact, than when people received their reward and had their curiosity satisfied.

"So," you may ask, "what's wrong with that answer? That seems reasonable and sound and very sciencey!"

You just got brain-mesmerized!

I can prove, with one statement, that this answer is wrong (if you're impatient, jump to point 2 at the bottom).

I'm not picking on the person who answered the question; they had no way to know. They were just following the discourse of the media narrative about neuroscience findings.

So what is wrong with this explanation (he says, finally getting to the damned point)? I'll break both of these points down in detail later.

1. The question is phrased in such a way that it presumes that "curiosity" is a singular thing.

2. The question presumes that a complex behavior or emotion can be localized to a brain region or regions. There are several philosophical pitfalls packaged into the answer, such as the ontological commitment to the narrative of cognitive neuroscience and the cerebral localization of function.

To be clear, what I'm not saying is that behaviors aren't in the brain. What I am saying is that the cerebral localization narrative is too simplistic.

Let me break down these points.

1. "Is curiosity a singular thing?"
When you ask "where is curiosity in the brain" you assume that researchers can somehow isolate curiosity from other emotions and behaviors in a lab and dissect it apart. This is very, very difficult, if not impossible. Neuroimaging (almost always) relies on the notion of cognitive subtraction, which is a way of comparing your behavior or emotion of interest (curiosity) against some baseline state that is not curiosity.

Or, as I say in my book chapter from The Mind and the Frontal Lobes:

The underlying assumption in these studies is that activity in brain networks alters in a task-dependent manner that becomes evident after averaging many event-related responses and comparing those against a baseline condition. Deviations from this baseline reflect a change in the neuronal processing demands required to perform the task of interest.

2. "Can curiosity be localized to one brain region?"
Bradley Voytek PNAS basal ganglia prefrontal cortex striatum

No, it cannot. Here's how I know: I've personally worked with people who have a severely damaged striatum. Know what? They still have curiosity. If the striatum is where curiosity is in the brain, how can someone whose striata are gone still have curiosity? They cannot. Yet they do. Poof. Hypothesis disproved.

Imagine asking "where is video located in my computer?" That doesn't make any sense. Your monitor is required to see the video. Your graphics card is required to render the video. The software is required to generate the code for the video. But the "video" isn't located anywhere in the computer.


Now there's a subtlety here. It may be that people with damaged striata have curiosity impairments (whatever that means), which would agree with the fMRI study discussed in that link above, but it proves that the striatum is not where curiosity is in the brain. More technically: the striatum may be a critical part of a network of brain regions that support curiosity behaviors, but that is different from saying that the striatum is where curiosity is.

Or, as I say in my chapter:

...the cognitive subtraction method... provide[s] details of functional localization that can then be tested and corroborated using other methodologies, including lesion studies. 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.

Thus, discussing behavioral functions outside of the context of the larger cortical and subcortical networks involved with that function is a poorly posed problem. Therefore, the scientific study of cognition requires detailed neuroanatomical and connectivity information to compliment functional activity findings.

God. I was going to end this with some links to news stories talking about neuroscientists finding out where (love/happiness/hate/prejudice/sexytimes/etc.) were located in the brain, but I just gave up. There are some damned many of them.

If you're a journalist and you're reading this, please change the way you talk about these results.

If you're a student, if you remember nothing else from this post, just remember to ask, "can a person who has a lesion to that brain region not experience that emotion or do that behavior anymore?" If the person still can, then that is not where that behavior is located in the brain. And, in all likelihood, that function can't be localized to any one region at all.

Editor's selection: Neuroscience
This post was chosen as an Editor's Selection for ResearchBlogging.org
Editor's selection: Social Science
This post was chosen as an Editor's Selection for ResearchBlogging.org
Barres, B. (2010). Neuro Nonsense PLoS Biology, 8 (12) DOI: 10.1371/journal.pbio.1001005
Racine E, Bar-Ilan O, & Illes J (2005). fMRI in the public eye. Nature Reviews Neuroscience, 6 (2), 159-64 PMID: 15685221
Editors (2004). Brain scam? Nature Neuroscience, 7 (7), 683-683 DOI: 10.1038/nn0704-683
Weisberg, D., Keil, F., Goodstein, J., Rawson, E., & Gray, J. (2008). The Seductive Allure of Neuroscience Explanations Journal of Cognitive Neuroscience, 20 (3), 470-477 DOI: 10.1162/jocn.2008.20040
Young, M., Hilgetag, C., & Scannell, J. (2000). On imputing function to structure from the behavioural effects of brain lesions Philosophical Transactions of the Royal Society B: Biological Sciences, 355 (1393), 147-161 DOI: 10.1098/rstb.2000.0555


  1. Thanks for the post Bradley. Very interesting. I just checked the original question on Quora and your answer is on top! I registered on Quora just to vote up your answer; not that it needs my vote to be on top. Cheers!

  2. Anonymous16:47

    I agree with every word here. More posts like these!

    These are basic concepts that most of the public (and, importantly, many neuroscientists) still haven't figured out. Thank you.

  3. Nice post, Brad! I think we might've met six years ago when I visited Berkeley as a prospective grad student. Anyways, good post. I'm going to go tweet it now..

  4. Anonymous20:09

    Good questions to ask, fully agree with you.
    Not only by neuroscientists.

    "Can I ask a question this way?"
    "Does it make sense?"
    "Ia there conflicting evidence?"
    "Can I think of some experiment/fact that would disprove my hypothesis?"

    Those are broad categories your questions 1 and 2 fall into that should be asked by every scientist / journalist.


  5. Livia: Did I give you a ride to the dinner or something?

  6. loveforscience: good point! I generally try to make claims that are less strong, but you're right. :)

  7. Hear hear! I've had a very similar beef myself lately.


  8. Hold on, no "poof" just yet! You forget a big possibility that would be consistent with both the conclusion that the striatum is responsible for curiosity and the observation that patients with striatum lesions still have possible unimpaired curiosity -- plasticity! i.e., a specific structure could very well be responsible/necessary for a given function in normal brains, but if it gets damaged, other parts of the brain can compensate.

    Not that I think that this actually happens in the case of curiosity/striatum, or that media coverage of neuroimaging findings is well-informed, but your lesion study alone may not disprove the hypothesis. :)

  9. Excellent post! Sometimes I wonder if functional imaging has actually set back progress in understanding the brain as asking "where" questions seems productive, but actually keeps us from asking the real "how" questions.

  10. Thanks Dean & Michelle! Dean, great post, by the way. Michelle, I couldn't agree more. Neuroscientists often confuse knowing what regions are associated with a behavior with understanding that behavior.

  11. Sarang: Touché. :) BUT, that's likely only true if there is time for reorganization, unless the information rerouting happens *very* quickly. If you examine someone with a striatal lesion in the acute stroke phase and they still show curiosity, then I think we're back to "hypothesis poofing" territory.

  12. I seem to remember Francis Crick announcing many years ago, while his "Astonishing Hypothesis" was still hot, that his lab had isolated free will. I laffed but I couldn't put words to why. Thank you.

  13. I always try to avoid using the following terms in regard to an aspect of cognitive function X and the brain:

    Causes X
    is responsible for X
    is the part of the brain that *does* X

    and instead I always try to say:

    (For neuroimaging studies)
    is associated with X

    (For lesion studies)
    is critical to the function of X but not necessarily sufficient for X

    It always takes a couple of minutes to explain what I mean, but its worth it in the end, as people always get what I'm talking about, at least when I give examples, rather than talking abstractly as I've done here.

    In lectures, I like to cite the dead Salmon brain activity study, as well as the voodoo correlations papers when talking about over reliance on neuroimaging studies.

  14. Tom: that's a good set of policies, and engaging people by having them think about what you're saying is always a good thing.

  15. I think people want quick, pat answers that work forever...I just heard a couple segments this weekend on Wisconsin Public Radio: a series stemming from Carl Jung's Red Book...I'm sure you have heard it. Frick's book was also mentioned. Thanks for writing....

  16. Very Nice post. When I was in college, I barely study neuroscience, and one of my favourit scientist was Gerard edelman. I' m not up to date in neuroscience, but, the theory of neural group selection doesnt give Nice insigths about the intricate net that are the higher brain functions? (as cousciouness).

    I may be speaking crap, but the TSGN came to my mind anile I read the post.