Saturday, June 28, 2008

Important new finding on linguistic primitives -- courtesy of The Onion

PASADENA, CA—A team of Caltech scientists announced Monday that they have discovered a type of conversational detail smaller than minutiae, the class of particulars long thought to be the smallest possible building blocks of mundanity. "These tiny sub-minutiae, or 'boredons,' are so insignificant that they contain almost no information, useless or otherwise," said head researcher Dr. Nathan Yang, adding that the conversationally inconsequential details naturally occur in elevators and other enclosed spaces containing high concentrations of vaguely familiar acquaintances. "At least six must be combined to make up a detail that even remotely approaches the declarative weight of a triviality, and more than 200 are required to compose a viable trifle." Yang said that the basic unit of tedium remained undiscovered for so long because boredons are instantly forgotten as soon as they are heard.

Headaches? Problems with Mirror Neurons??

No worries! You can stimulate yourself using a new hand-held device. No, we are not turning into a different kind of blog ... It's still rated G. (Or maybe PG).

Courtesy of Bill Idsardi of Talking Brains East, here the info, regarding TMS devices that might be a nice holiday gift:

"The device, about the size of a hair dryer, is put up against the back of the head, and users push a button to administer the magnetic pulse. The study showed it eliminated the headache within two hours for 39 percent of participants; 22 percent in the placebo group reported no pain two hours later. Study participants used the device twice per migraine episode within an hour of experiencing an aura. Up to three migraines were treated per patient over a three-month period."

Can you imagine how crappy you must feel to combat migraine with TMS, such a gentle and mellow technique? Sounds dreadful to me -- and I get migraines regularly. I'd rather eat lint then undergo TMS during a migraine.

Logothetis (2008): A must read for proponents of *anything* (and everthing)

Nikos Logothetis has written an important review about fMRI. "What we can do and what we cannot do with fMRI" -- published in Nature a couple of weeks ago -- is essential reading for anyone using fMRI, anyone playing with fMRI analysis, and anyone thinking about cognitive neuroscience and computational neuroscience.

Nikos has the street cred to say the things he says because he really really does understand what he is doing when he is doing fMRI.

The paper discusses the prospects and problems of understanding the relation between hemodynamics and neuronal activity. But this is not just theoretical analysis -- check out the measurements of the amount of vasculature per unit of cortex compared to the amount of neuronal tissue ... Yikes!

Anyway, in this paper, from one of the premier practitioners of fMRI, come the smackdown. Informative and important, and a good reminder that we should not give up electrophysiology, single-unit recording, or any other techniques, for that matter.

AND: If you want to get a bit more nerdy about this and learn more about how cells generate the stuff we are measuring and interpreting, this news study on the contribution of astrocytes from Mriganka Sur's lab is pretty interesting:

Tuned Responses of Astrocytes and Their Influence on Hemodynamic Signals in the Visual Cortex. James Schummers, Hongbo Yu, and Mriganka Sur. Science 20 June 2008: 1638-1643.

Wednesday, June 25, 2008

Mahon & Caramazza (2008): A must read for proponents of "embodied cognition"

At the risk of turning Talking Brains into a blog exclusively dedicated to mirror neurons, here is yet another post on the topic. But the fact is, mirror neurons and embodied cognition have become such a dominant force in cognitive neuroscience and psychology, with obvious implications for work on language and brain, that the topic needs to be addressed thoroughly and frequently.

So our latest survey on mirror neurons is in. Forty-five percent of respondents (the majority!) said THE "MIRROR SYSTEM" THE BASIS FOR (I.E., PLAYS THE DOMINANT ROLE IN) ACTION UNDERSTANDING. Another 23% were unsure. Only 30% of respondents actually got the answer right.

This is a bizarre result (although it reflects the dominant view in cognitive neuroscience) because all the available evidence points to the conclusion that the mirror system is NOT the basis for action understanding. Have a look at the speech or apraxia literature and one finds double-dissociations between the ability to recognize actions and produce actions. Either people have not read the relevant literature, or have decided to believe in "mirror system theory" on faith alone.

In case of the former situation, I suggest the following paper as a must-read:

A critical look at the embodied cognition hypothesis and a new proposal for grounding conceptual content

Bradford Z. Mahon, a, b, and Alfonso Caramazzaa, b
Journal of Physiology-Paris
Volume 102, Issues 1-3, January-May 2008, Pages 59-70

Many studies have demonstrated that the sensory and motor systems are activated during conceptual processing. Such results have been interpreted as indicating that concepts, and important aspects of cognition more broadly, are embodied. That conclusion does not follow from the empirical evidence. The reason why is that the empirical evidence can equally be accommodated by a ‘disembodied’ view of conceptual representation that makes explicit assumptions about spreading activation between the conceptual and sensory and motor systems. At the same time, the strong form of the embodied cognition hypothesis is at variance with currently available neuropsychological evidence. We suggest a middle ground between the embodied and disembodied cognition hypotheses – grounding by interaction. This hypothesis combines the view that concepts are, at some level, ‘abstract’ and ‘symbolic’, with the idea that sensory and motor information may ‘instantiate’ online conceptual processing.

Tuesday, June 24, 2008

Broca's area is not part of the human mirror system

This is the conclusion from an interesting and thoughtful review by Morin and Grezes (2008, Clinical Neurophysiology, 38: 189-195). The basic observation is that the response of BA 44 (the posterior portion of Broca's area) does not discriminate between goal-directed and non-goal-directed actions, whereas BA 6 (a more posterior pre-motor site) does, responding more reliably across studies to goal-directed action. As macaque mirror neurons only respond goal-directed actions, this makes BA 6 the more likely candidate for the human homologue of monkey F5.

Of course the recent discovery of mirror neurons in monkey primary motor cortex (Tkach D, et al. 2007, Congruent activity during action and action observation in motor cortex. J Neurosci 27:13241-13250.) , kind of throws a monkey wrench into the whole mirror neuron enterprise. In the original reports did not find mirror neurons in M1 which was rightfully argued to be evidence against the possibility that the monkeys were covertly generating movement responses during the perception of actions. In other words, it ruled out the possibility that “mirror” responses were merely some kind of unimplemented motor reflex. This important "control" opened the door to a more interesting higher-level, function for mirror neurons. Now with the demonstration of “mirror” responses in low-level motor circuitry, it is entirely possible that “mirror” responses are nothing more than reflexive sensory-motor associations.

Thursday, June 19, 2008

Results of votes on MNs -- please elucidate!

OK, I am now definitely ready to hear from people who are participating in this blog -- for example by voting -- but remaining silent ...

In a previous vote, on the role of mirror neurons in speech perception ('primary substrate'), 25% said YES, 56% said NO, and 18% NOT SURE.

Now, on the 'action understanding question' (dominant role etc), it's 45% YES, 30% NO, and 24% NOT SURE.

I don't follow ... Admittedly, in the first poll there were fewer voters. Does that mean that we suddenly have readers/participants from the enthusiastcally pro-MN community? Or does that mean that people have a principled model of action understanding versus speech understanding that licenses such a conclusion? Or does it mean that our understanding of 'action' is so underspecified that *any* answer is sufficient?

Because I am naively optimistic, I am assuming that there are detailed accounts of action understanding that motivate the conclusion that mirror neurons form the basis for this complex cognitive subroutine. So can someone please clue me in on the evidence?

Needing to know ...

Wednesday, June 18, 2008

New look and renewed success for Brain and Language

The journal Brain and Language has a new look. It's not just cover art that's different about the journal though. Editor Steve Small has put in some serious work to restore Brain and Language to its former glory as THE premier journal for publication of research on the neurobiology of language. There was a period a few years back when publication time-lines were prohibitively slow, which led to fewer submissions, and a drop off in quality. If you've reviewed for or submitted to B&L lately though, you'll know that slow turn around is a thing of the past (reviewers are strongly encouraged to submit reviews within two weeks), and quality is back where it should be.

The proof is in the pudding. The latest Thomson-Reuters Scientific Journal Citation Reports show that Brain and Language continues to increase its Impact Factor, which is now at 2.641 -- quite good for a specialized journal. This puts Brain and Language at #91/200 among journals in neuroscience, #16/72 among journals of psychology, and #1 of 55 journals of linguistics.

I notice that the current issue has a paper by Prof. Poeppel (an index of high standards for sure!), and watch for a future special issue guest-edited by yours truly, on (what else) Mirror Neurons and Speech. Should be an interesting and provocative issue.

Definitely put B&L on your list of journals to scan every month. Many thanks to Steve Small for his hard work! Well done Steve!

Monday, June 16, 2008

The mirror system is involved in what?! Is this for real?

The mirror system isn't just for grasping anymore, according to a new study published by Mouras and colleagues in NeuroImage. I just have two questions: Is there anything that the frontal operculum won't respond to? And is there anything that won't be attributed to mirror neuron function? Ramachandran calls this study "bold." I think I will withhold further commentary on this one, although our hit count would probably skyrocket if I did. Just click here and evaluate for yourself.

Noun Meaning: An Interesting But Peculiar Paper in Science

In the May 30 issue of Science there is a paper by Mitchell et al. with the provocative title, 'Predicting Human Brain Activity Associated with the Meanings of Nouns.' That is quite a promise. I think this paper shows a really innovative way to look at fMRI data; I also think that it raises more questions than it answers with respect to the meaning of nouns.

The paper presents a computational model that is trained using a trillion-word text corpus and observed fMRI data, and that is then used to predict the pattern of fMRI responses for new words. The model is based on the following: "First, it assumes the semantic features that distinguish the meanings of arbitrary concrete nouns are reflected in the statistics of their use within a very large text corpus. ... Second, it assumes that the brain activity observed when thinking about any concrete noun can be derived as a weighted linear sum of contributions from each of its semantic features."

I think this computational modeling idea is really quite cool, but I am also puzzled by the presuppositions. For example, I just don't understand what 'meaning' means when it seems to simply follow from co-occurrence statistics. The intuition appears to be that you can find 'intermediate semantic features,' but when you read the paper, those intermediate semantic features themselves must be found in the corpus. Here they are simply given to the model, but on a co-occurrence statistics view of the world, doesn't the learner have to actually get this information? Anyway, I find this fascinating and would like to learn more, but it does make specific assumptions about how meaning comes about that require more explanation, at least for someone like me. Furthermore, the second assumption, that a weighted linear sum of the contribution of semantic features constitutes the meaning, is no less puzzling.

The type of material that seems to be captured pretty well in this approach are concrete nouns as well as verbs with very obvious sensory-motor features. And indeed, the authors argue that their model "lends credence to the conjecture that neural representations of concrete nouns are in part grounded in sensory-motor features." Okay, so here they're telling us something quite specific, in line perhaps with the way Alex Martin would think about the problem. But right after that they say that "it appears that the basis set of features that underlie neural representations of concrete nouns involves much more than sensory-motor cortical regions." Well now it sounds like they want to have their cake and eat it too. And who doesn't?!

The experiment strikes me as a very creative way to interrogate fMRI data, but I think the central question remains really hard to tackle. "What is the basis set of semantic features and corresponding components of neural activations encoding meanings of concrete nouns?"

Let's say this theory is exactly right. That is, corpus statistics + sensory-motor features are a sufficient description for concrete nouns and action verbs (a conclusion that I think is pretty dodgy). Does that mean that to extend this to other aspects of meaning we need an entirely different theory? For example, how are we going to deal with a) abstraction, b) closed-class words, and c) any kind of compositionality? I do think it's inspiring that hard-core computational methods are allowing us to look at these complex data sets with new 'glasses.' But I still think that the cognitive science part, and in this case the semantics, need to be very carefully looked at in the context of interpreting such provocative data sets.

I hope either Greg or any reader or commenter can enlighten or teach me more about this intriguing new paper.

Monday, June 9, 2008

The Motor Theory Critiqued - History repeats itself

I dug up this VERY interesting paper by Walter B. Pillsbury. It is the President's Address, at the 1910 American Psychological Association meeting. It was published in 1911 in Psych Review (Pillsbury, W.B. (1911). The place of movement in consciousness. Psychological Review, 18(2), 83-99.)

It seems that motor theories were all the rage back in 1910 just as they are today. And according to Pillsbury, despite this widespread belief in motor theories, there was little to no evidence in favor of the view, and much reason to doubt it. We've pointed out in this blog that the same situation holds of mirror neurons today.

Here's my favorite quote:

"The [motor] theory is so simple and so easy to present that every one is glad to believe it. The only question that any one cares to raise is how much of it will the known facts permit one to accept." p. 84.

Here's my second favorite quote:

"A reader of some of the texts lately published would be inclined to believe that there was nothing in consciousness but movement, and that the presence of sense organs, or of sensory and associatory tracts in the cortex was at the least a mistake on the part of the Creator." p. 83.

Read your history! You really can learn from the mistakes of the past.

Thursday, June 5, 2008


The Brain and Language Lab at Georgetown
University investigates the biological and
psychological bases of first and second language,
and the relations between language and other
cognitive domains, including memory, music and
motor function. The lab's members test their
hypotheses using a set of complementary
behavioral, neurological, neuroimaging (ERP, MEG,
fMRI) and other biological (genetic, endocrine,
pharmacological) approaches. They are interested
in the normal acquisition and processing of
language and non-language functions, and their
neurocognitive variability as a function of
factors such as genetics, hormones, sex,
handedness, age and learning environment; and in
the breakdown, recovery and rehabilitation of
language and non-language functions in a variety
of disorders, including Specific Language
Impairment, ADHD, dyslexia, autism, Tourette
syndrome, Alzheimer's disease, Parkinson's
disease, Huntington's disease, and aphasia. For a
fuller description of the Brain and Language Lab,
please go to

We are seeking a full-time Research Assistant/Lab
Manager. The successful candidate, who will work
with the other RA/Lab Managers currently in the
lab, will have the opportunity to be involved in
a variety of projects, using a range of
methodological approaches (see above and S/he will have
responsibility for various aspects of research
and laboratory management and organization,
including creating experimental stimuli; setting
up and running experiments on a variety of
subject groups; performing statistical analyses;
helping manage the lab’s computers; managing
undergraduate assistants; and working with the
laboratory director and other lab members in
preparing and managing grants and IRB protocols.

Minimum requirements for the position include a
Bachelor's or Master's degree, with a significant
amount of course-work or research experience in
at least two and ideally three of the following:
linguistics, cognitive psychology, neuroscience,
computer science, and statistics. Familiarity
with Windows (and ideally Linux) is highly
desirable, as is experience in programming or
statistics and/or a strong math aptitude. A car
is preferable because subject testing is
conducted at multiple sites. The candidate must
be extremely responsible, reliable, energetic,
hard-working, organized, and efficient, and be
able to work with a diverse group of people.

To allow for sufficient time to learn new skills
and to be productive, candidates should be
available to work for at least two years, and
ideally for three. Preference will be given to
candidates who can begin immediately. Interested
candidates should email Marco PiƱeyro
( their CV and one or two
publications or other writing samples, and have 3
recommenders email him their recommendations
directly. Salary will be commensurate with
experience and qualifications. The position,
which includes health benefits, is NIH-funded.
Georgetown University is an Affirmative Action/Equal Opportunity employer.

Monday, June 2, 2008

Mirror neuron survey

I posted a mirror neuron survey a couple of days ago, and we now have a small sample of responses. If this sample is representative, it seems there's a lot of divergent opinions and/or uncertainty about the role of mirror neurons in action understanding. I would LOVE to hear particularly from those of you who are voting either "yes" (mirror neurons ARE the basis for action understanding), or "not sure." Please let us know why you are voting the way you are. What evidence leads you to vote "yes"? Why are you unsure? This is a perfect opportunity to discuss these issues outside of the stiff, non-interactive journal format, and outside of the time-constrained, senior researcher-dominated conference format. You can even comment anonymously here. How easy is that?! So speak up! I promise to be nice. :-)