Tag: cognitive neuroscience

the naming of things

Let’s suppose you were charged with the important task of naming all the various subdisciplines of neuroscience that have anything to do with the field of research we now know as psychology. You might come up with some or all of the following terms, in no particular order:

  • Neuropsychology
  • Biological psychology
  • Neurology
  • Cognitive neuroscience
  • Cognitive science
  • Systems neuroscience
  • Behavioral neuroscience
  • Psychiatry

That’s just a partial list; you’re resourceful, so there are probably others (biopsychology? psychobiology? psychoneuroimmunology?). But it’s a good start. Now suppose you decided to make a game out of it, and threw a dinner party where each guest received a copy of your list (discipline names only–no descriptions!) and had to guess what they thought people in that field study. If your nomenclature made any sense at all, and tried to respect the meanings of the individual words used to generate the compound words or phrases in your list, your guests might hazard something like the following guesses:

  • Neuropsychology: “That’s the intersection of neuroscience and psychology. Meaning, the study of the neural mechanisms underlying cognitive function.”
  • Biological psychology: “Similar to neuropsychology, but probably broader. Like, it includes the role of genes and hormones and kidneys in cognitive function.”
  • Neurology: “The pure study of the brain, without worrying about all of that associated psychological stuff.”
  • Cognitive neuroscience: “Well if it doesn’t mean the same thing as neuropsychology and biological psychology, then it probably refers to the branch of neuroscience that deals with how we think and reason. Kind of like cognitive psychology, only with brains!”
  • Cognitive science: “Like cognitive neuroscience, but not just for brains. It’s the study of human cognition in general.”
  • Systems neuroscience: “Mmm… I don’t really know. The study of how the brain functions as a whole system?”
  • Behavioral neuroscience: “Easy: it’s the study of the relationship between brain and behavior. For example, how we voluntarily generate actions.”
  • Psychiatry: “That’s the branch of medicine that concerns itself with handing out multicolored pills that do funny things to your thoughts and feelings. Of course.”

If this list seems sort of sensible to you, you probably live in a wonderful world where compound words mean what you intuitively think they mean, the subject matter of scientific disciplines can be transparently discerned, and everyone eats ice cream for dinner every night terms that sound extremely similar have extremely similar referents rather than referring to completely different fields of study. Unfortunately, that world is not the world we happen to actually inhabit. In our world, most of the disciplines at the intersection of psychology and neuroscience have funny names that reflect accidents of history, and tell you very little about what the people in that field actually study.

Here’s the list your guests might hand back in this world, if you ever made the terrible, terrible mistake of inviting a bunch of working scientists to dinner:

  • Neuropsychology: The study of how brain damage affects cognition and behavior. Most often focusing on the effects of brain lesions in humans, and typically relying primarily on behavioral evaluations (i.e., no large magnetic devices that take photographs of the space inside people’s skulls). People who call themselves neuropsychologists are overwhelmingly trained as clinical psychologists, and many of them work in big white buildings with a red cross on the front. Note that this isn’t the definition of neuropsychology that Wikipedia gives you; Wikipedia seems to think that neuropsychology is “the basic scientific discipline that studies the structure and function of the brain related to specific psychological processes and overt behaviors.” Nice try, Wikipedia, but that’s much too general. You didn’t even use the words ‘brain damage’, ‘lesion’, or ‘patient’ in the first sentence.
  • Biological psychology: To be perfectly honest, I’m going to have to step out of dinner-guest character for a moment and admit I don’t really have a clue what biological psychologists study. I can’t remember the last time I heard someone refer to themselves as a biological psychologist. To an approximation, I think biological psychology differs from, say, cognitive neuroscience in placing greater emphasis on everything outside of higher cognitive processes (sensory systems, autonomic processes, the four F’s, etc.). But that’s just idle speculation based largely on skimming through the chapter names of my old “Biological Psychology” textbook. What I can definitively confidently comfortably tentatively recklessly assert is that you really don’t want to trust the Wikipedia definition here, because when you type ‘biological psychology‘ into that little box that says ‘search’ on Wikipedia, it redirects you to the behavioral neuroscience entry. And that can’t be right, because, as we’ll see in a moment, behavioral neuroscience refers to something very different…
  • Neurology: Hey, look! A wikipedia entry that doesn’t lie to our face! It says neurology is “a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue, such as muscle.” That’s a definition I can get behind, and I think 9 out of 10 dinner guests would probably agree (the tenth is probably drunk). But then, I’m not (that kind of) doctor, so who knows.
  • Cognitive neuroscience: In principle, cognitive neuroscience actually means more or less what it sounds like it means. It’s the study of the neural mechanisms underlying cognitive function. In practice, it all goes to hell in a handbasket when you consider that you can prefix ‘cognitive neuroscience’ with pretty much any adjective you like and end up with a valid subdiscipline. Developmental cognitive neuroscience? Check. Computational cognitive neuroscience? Check. Industrial/organizational cognitive neuroscience? Amazingly, no; until just now, that phrase did not exist on the internet. But by the time you read this, Google will probably have a record of this post, which is really all it takes to legitimate I/OCN as a valid field of inquiry. It’s just that easy to create a new scientific discipline, so be very afraid–things are only going to get messier.
  • Cognitive science: A field that, by most accounts, lives up to its name. Well, kind of. Cognitive science sounds like a blanket term for pretty much everything that has to do with cognition, and it sort of is. You have psychology and linguistics and neuroscience and philosophy and artificial intelligence all represented. I’ve never been to the annual CogSci conference, but I hear it’s a veritable orgy of interdisciplinary activity. Still, I think there’s a definite bias towards some fields at the expense of others. Neuroscientists (of any stripe), for instance, rarely call themselves cognitive scientists. Conversely, philosophers of mind or language love to call themselves cognitive scientists, and the jerk cynic in me says it’s because it means they get to call themselves scientists. Also, in terms of content and coverage, there seems to be a definite emphasis among self-professed cognitive scientists on computational and mathematical modeling, and not so much emphasis on developing neuroscience-based models (though neural network models are popular). Still, if you’re scoring terms based on clarity of usage, cognitive science should score at least an 8.5 / 10.
  • Systems neuroscience: The study of neural circuits and the dynamics of information flow in the central nervous system (note: I stole part of that definition from MIT’s BCS website, because MIT people are SMART). Systems neuroscience doesn’t overlap much with psychology; you can’t defensibly argue that the temporal dynamics of neuronal assemblies in sensory cortex have anything to do with human cognition, right? I just threw this in to make things even more confusing.
  • Behavioral neuroscience: This one’s really great, because it has almost nothing to do with what you think it does. Well, okay, it does have something to do with behavior. But it’s almost exclusively animal behavior. People who refer to themselves as behavioral neuroscientists are generally in the business of poking rats in the brain with very small, sharp, glass objects; they typically don’t care much for human beings (professionally, that is). I guess that kind of makes sense when you consider that you can have rats swim and jump and eat and run while electrodes are implanted in their heads, whereas most of the time when we study human brains, they’re sitting motionless in (a) a giant magnet, (b) a chair, or (c) a jar full of formaldehyde. So maybe you could make an argument that since humans don’t get to BEHAVE very much in our studies, people who study humans can’t call themselves behavioral neuroscientists. But that would be a very bad argument to make, and many of the people who work in the so-called “behavioral sciences” and do nothing but study human behavior would probably be waiting to thump you in the hall the next time they saw you.
  • Psychiatry: The branch of medicine that concerns itself with handing out multicolored pills that do funny things to your thoughts and feelings. Of course.

Anyway, the basic point of all this long-winded nonsense is just that, for all that stuff we tell undergraduates about how science is such a wonderful way to achieve clarity about the way the world works, scientists–or at least, neuroscientists and psychologists–tend to carve up their disciplines in pretty insensible ways. That doesn’t mean we’re dumb, of course; to the people who work in a field, the clarity (or lack thereof) of the terminology makes little difference, because you only need to acquire it once (usually in your first nine years of grad school), and after that you always know what people are talking about. Come to think of it, I’m pretty sure the whole point of learning big words is that once you’ve successfully learned them, you can stop thinking deeply about what they actually mean.

It is kind of annoying, though, to have to explain to undergraduates that, DUH, the class they really want to take given their interests is OBVIOUSLY cognitive neuroscience and NOT neuropsychology or biological psychology. I mean, can’t they read? Or to pedantically point out to someone you just met at a party that saying “the neurological mechanisms of such-and-such” makes them sound hopelessly unsophisticated, and what they should really be saying is “the neural mechanisms,” or “the neurobiological mechanisms”, or (for bonus points) “the neurophysiological substrates”. Or, you know, to try (unsuccessfully) to convince your mother on the phone that even though it’s true that you study the relationship between brains and behavior, the field you work in has very little to do with behavioral neuroscience, and so you really aren’t an expert on that new study reported in that article she just read in the paper the other day about that interesting thing that’s relevant to all that stuff we all do all the time.

The point is, the world would be a slightly better place if cognitive science, neuropsychology, and behavioral neuroscience all meant what they seem like they should mean. But only very slightly better.

Anyway, aside from my burning need to complain about trivial things, I bring these ugly terminological matters up partly out of idle curiosity. And what I’m idly curious about is this: does this kind of confusion feature prominently in other disciplines too, or is psychology-slash-neuroscience just, you know, “special”? My intuition is that it’s the latter; subdiscipline names in other areas just seem so sensible to me whenever I hear them. For instance, I’m fairly confident that organic chemists study the chemistry of Orgas, and I assume condensed matter physicists spend their days modeling the dynamics of teapots. Right? Yes? No? Perhaps my  millions thousands hundreds dozens three regular readers can enlighten me in the comments…

the Bactrian camel and prefrontal cortex: evidence from somatosensory function

I’ve been swamped with work lately, and don’t expect to see the light at the end of the tunnel for a few more weeks, so there won’t be any serious blogging here for the foreseeable future. But on a completely frivolous note, someone reminded me the other day of a cognitive neuroscience paper title generator I wrote a few years ago and had forgotten about. So I brushed it off and added a small amount of new content, and now it’s alive again here. I think it’s good for a few moments of entertainment, and occasionally produces a rare gem–like the one in the title of this post, or my all-time favorite, Neural correlates of nicotine withdrawal in infants.

Feel free to post any other winners in the comments…

everything we know about the neural bases of cognitive control, in 20 review articles or less

Okay, not everything. But a lot of what we know. The current issue of Current Opinion in Neurobiology, which features a special focus on cognitive neuroscience, contains are almost 20 short review papers, most of which focus on the neural mechanisms of cognitive control in one guise or another. As the Editors of the special issue (Earl Miller and Liz Phelps) explain in their introduction:

Our goal with this special issue was to highlight integrative approaches to brain function. To this end, we focused on the most integrative of brain functions, cognitive control. Cognitive, or executive, control is the ability to coordinate thought and action by directing them toward goals, often far removed goals.

I’ve only skimmed a couple of articles so far, but it’s a pretty impressive table of contents, and I’m looking forward to reading a lot of the reviews. The nice thing about the Current Opinion series, like the Trends series, is that the reviews are short and focused, so they’re well-suited to people who are very busy and don’t have enough hours in their day (like you), or people who just have a short attention span (like me).

Admittedly, I also have an ulterior motive for mentioning this issue: Todd Braver, Mike Cole and I contributed one of the articles, in which we review the neural bases of individual differences in executive control. I think it’s a really nice paper, the credit for which really goes to Todd and Mike–I mostly just contributed the section on methodological considerations (which is basically a precis of a much longer chapter I wrote with Todd a couple of years ago). Todd and Mike somehow managed to review work on everything from reward and motivation to emotion regulation to working memory capacity to dopamine genes, all in the space of eight pages. It’s a nice review highlighting the importance of modeling not only the central tendency of people’s behavior and brain activation in cognitive neuroscience studies, but also the variation between individuals. Aside from the fact that many people (including me!) find individual differences in cognitive abilities intrinsically interesting, an individual differences approach can provide insights that naturally complement those identified by more common within-subject analyses.

For instance, there’s a giant literature on the critical role the neurotransmitter dopamine plays in maintaining and updating goal representations. Most process models of dopamine function make either explicit or tacit predictions about how individual differences in dopamine function should manifest behaviorally, and recent studies have sought to test some of these predictions using both neuroimaging and molecular genetic techniques. A lot of work has focused on a common polymorphism in the COMT gene, variants of which dramatically alter the efficiency of dopamine degradation in the prefrontal cortex. An (admittedly simplistic) prediction that follows from one standard view of prefrontal dopamine function (that tonic dopamine serves to stabilize active representations) is that people who possess the low-activity met allele (and consequently have higher dopamine levels in PFC) should have a greater capacity to maintain goal representations and sustain attention, which may manifest as improved performance on many working memory tasks. Conversely, people with the val allele, which is associated with lower tonic dopamine levels in PFC, should do worse at tasks requiring sustained attention, but may have greater cognitive flexibility (due to the capacity to switch between goal representations more easily).

This prediction, which is borne out by a number of studies we review, is fundamentally about individual differences, since we typically can’t manipulate people’s COMT genes in the lab (though I know some people who probably really wish we could!). But the point is, even if you’re not intrinsically interested in what makes people different from one another, studying individual variation at a genetic, neural, or behavioral level can often tell you something useful about the models you’re developing. Particularly when it comes to the domain of executive control, where differences between individuals can be quite striking. Almost any mechanistic model of executive control is going to have ‘joints’ that could theoretically vary systematically across individuals, so it makes sense to capitalize on natural variability between people to test some of the predictions that fall out of the model, instead of just treating between-subject variability as the error term in your one-sample t-test.

Anyway, our article is here, and the full issue is here (though it’s behind a paywall, unfortunately).

building a cumulative science of human brain function at CNS

Earlier today, I received an email saying that a symposium I submitted for the next CNS meeting was accepted for inclusion in the program. I’m pretty excited about this; I think the topic of the symposium is a really important one, and this will be a great venue to discuss some of the relevant issues. The symposium is titled “Toward a cumulative science of human brain function”, which is a pretty good description of its contents. Actually, I stole borrowed that title from one of the other speakers (Tor Wager); originally, the symposium was going to be called something like “Cognitive Neuroscience would Suck Less if we all Pooled our Findings Together Instead of Each Doing our own Thing.” In hindsight, I think title theft was the right course of action.  Anyway, with the exception of my own talk, which is assured of being perfectly mediocre, the line-up is really stellar; the other speakers are David Van Essen, Tor Wager (my current post-doc advisor), and Russ Poldrack, all of whom do absolutely fantastic research, and give great talks to boot. Here’s the symposium abstract:

This symposium is designed to promote development of a cumulative science of human brain function that advances knowledge through formal synthesis of the rapidly growing functional neuroimaging literature. The first speaker (Tal Yarkoni) will motivate the need for a cumulative approach by highlighting several limitations of individual studies that can only be overcome by synthesizing the results of multiple studies. The second speaker (David Van Essen) will discuss the basic tools required in order to support formal synthesis of multiple studies, focusing particular attention on SumsDB, a massive database of functional neuroimaging data that can support sophisticated search and visualization queries. The third and fourth speakers will discuss two different approaches to combining and filtering results from multiple studies. Tor Wager will review state-of-the-art approaches to meta-analysis of fMRI data, providing empirical examples of the power of meta-analysis to both validate and disconfirm widely held views of brain organization. Russell Poldrack will discuss a novel taxonomic approach that uses collaboratively annotated meta-data to develop formal ontologies of brain function. Collectively, these four complementary talks will familiarize the audience with (a) the importance of adopting cumulative approaches to functional neuroimaging data; (b) currently available tools for accessing and retrieving information from multiple studies; and (c) state-of-the-art techniques for synthesizing the results of different functional neuroimaging studies into an integrated whole.

Anyway, I think it’ll be a really interesting set of talks, so if you’re at CNS next year, and find yourself hanging around at the convention center for half a day (though why you’d want to do that is beyond me, given that the conference is in MONTREAL), please check it out!