Thursday, November 20, 2008

And apropos semantics: new NRN paper by TB East

At the Society for Neuroscience meeting in DC this past week, I met several people who -- willingly -- admitted to reading this blog. Thank you! Please, though (like I said at SfN), do comment more. It's more fun to hear from more people. Seriously. I won't name names, but, say, if your last name starts with H and ends with -erdman, and you are exceptionally experienced with electrophysiological studies, you should feel free to set us straight. Jonas, you should certainly write more. You are as opinionated as we are (and more well read than I am, although Greg knows everything), so bring it on. Martin, I know you are quietly lurking in the background ... Sonja and Richard -- come on! You *know* you wanna comment :-)

I'd like to hear what people thought of SfN. I had to miss the last two days -- during which most of the relevant stuff occurred -- but what I saw Saturday-Monday was pretty underwhelming. There was a nice talk by Manon Grube from Tim Griffiths' lab on the contribution of cerebellar circuitry to temporal analysis (lesion and stimulation data). Were there any highlights on language or speech or mirror neurons? How was Rizzolatti's plenary talk? I just spent a day with Ramachandran in LA at a different event, and he mentioned to me that he would not be surprised if Rizzolatti was awarded a Nobel Prize. 

And in that vein: Greg, congrats on getting the mirror neuron review accepted. I look forward to the discussion it elicits. Can you post a pre-print here for us all to read now?    

As for another new talkingbrains reading: In the new issue of Nature Reviews Neuroscience, there is a paper by Lau et al. on semantics. Ellen Lau did a magnificent job synthesizing a remarkable amount of data on the N400 to argue for a model that is illustrated in this review. It's called A cortical network for semantics: (de)constructing the N400. We would be interested in discussion on this, of course.


Yisrael said...

I'd be happy to comment on the article if you'd be so kind as to provide a link to a pdf copy of the article for those of us working in underprivileged institutions.

David Poeppel said...

hi yisroel, i will put a link to it on my web page as soon as i'm back from a trip.

Greg Hickok said...

I think this is a first folks. According to the new NRN paper, David says "where" matters! I quote, "Here we show that evidence bearing on WHERE the N400 response is generated provides key insights into WHAT it reflects." Unless your co-authors slipped it in the at the last minute, I think this means you are officially a brain mapper! Looking forward to reading the whole thing...

Jonathan Peelle said...

With respect to SfN, I thought it was fairly good this year. What I like best is the chance to see data from labs I don't generally run into at cognitive conferences. Dean Buonomano, for example, had a very nice poster looking at neural responses in rat auditory cortex to event contingencies---that is, hearing two items, it was possible to discriminate between various possible combinations based solely on the neural response to the second item. There was also a nice paper form Ross Maddox in Kamal Sen's lab about neural responses to time-warped songs in zebra finches.

And overall, I thought there were quite a few nice speech/language posters and talks. So I chalk it up as a success.

The Vlad said...

I think it would be the low point for neuroscience if Rizzolatti were to win the Nobel prize. His papers contain among the most poorly-controlled experiments in all of neuroscience. I won't even begin to say what I think about the over-interpretation of the data in which he and others have indulged. That he has been so successful is a sad indictment on the level of training that the average neuroscientist receives.

Yisrael said...

OK, it took a while but I finally got a copy of this article and read it. First, it is an excellent review of the literature dealing with the topic and indeed very helpful. There are however some issues that seemed lacking which may be a result of the source articles themselves or a conscious decision on the authors' part to keep the article a manageable length. They are:
1) The use of gyri and sulci as anatomical references (yes I know the tables used BA numbers). I am often frustrated by the imbalance between temporal and spatial resolution. Articles often use Talairach or MNI coordinates, perhaps this would be more specific.
2)Although the article discusses that there is modulation of N400 in response to various tasks there is no discussion of how that variance is made manifest. Is it a function of more neurons firing? If that is the case, why should more neurons be enlisted where there is facilitated access ? Also doesn't "facilitated access" seem to be at odds with N400 being associated with semantic anamoly?
I admit to being a bit of a novice in this field, perhaps you can set me straight.

Ellen Lau said...

Hi Yisroel,

Thanks for your comments. I agree with the concern about how to pinpoint the anatomy in this kind of review. I think in a field like this one you come up against a sort of significant digits problem; many of the papers you're reviewing did not localize the region with any kind of precision, so it seems artificial to pretend to do so in the meta-analysis. For whatever reason, many people working on language seem to have been pretty happy to say that certain kinds of functions are 'posterior temporal' and leave it at that. I hope that by providing a hypothesis that's just one step more specific, we'll motivate a lot of language people who want to prove us wrong to begin to be more precise in reporting their data.

As to your second question, that is exactly the point of the paper, to argue that the N400 is NOT associated with semantic anomaly, but that in many studies, anomaly was confounded with predictability. Poor Marta Kutas presented it as a semantic anomaly response when she first discovered it, and then 4 years later realized that it was probably predictability instead, but by then it was too late! She's spent the 20 years since trying to get people to realize that the N400 is not really semantic anomaly, but it doesn't seem to have had too much effect outside of the narrower ERP field. And I think that's why most of the fMRI sentence papers we reviewed didn't have appropriately designed materials, because few people in the broader field are aware that the association of semantic anomaly with the N400 is even in question.