Friday, November 30, 2007

Mirror Neuron Survey Results

Ok, the results are in! A majority (62%) of Talking Brains readers shun mirror neurons as the primary substrate for speech perception. Only 13% believe these cells play a critical role, and 23% are not sure. I personally, would love to have a discussion here between those of us who don't believe the mirror neuron theory of speech perception and those who do. It doesn't have to get nasty. I has some great face to face discussions with my former post doc Stephen Wilson about this stuff. Stephen came from Iacoboni's lab, which has published on the role of motor areas in speech perception. We ended up coming to a reasonable consensus, I think. (Of course, he did leave for UCSF so...) So speak up on the topic! New survey coming soon.

Post Doc Opportunities -- Moss Rehab & UC Irvine

A new post doc opportunity has opened up at Moss Rehab in Philadelphia. This is a great lab!

Also, Hickok lab is still looking to fill a post doc position. Contact Lisette Isenberg (

The Language and Aphasia Laboratory of Moss Rehabilitation Research Institute (MRRI), Philadelphia PA. is accepting applications for post-doctoral fellowships and full-time BA/BS assistantships, starting Spring or Summer 2008. Under the direction of Myrna Schwartz, Ph.D., the laboratory conducts research on normal and aphasic language processes. Topics include connectionist modeling of lexical disorders, cognitive control in short-term memory and language processing, and advanced methods of lesion-symptom mapping. Candidates can expect on-the-job training in patient research. Send cover letter, C.V., and references to Laura Barde:
email:; fax: 215-456-9613; mail: Moss Rehabilitation
Research Institute, 1200 West Tabor Road, MossRehab 4th fl. Sley, Philadelphia, PA, 19141.

Wednesday, November 28, 2007

Nature Reviews Neuroscience Research Highlights

Last month I posted a pretty harsh commentary on a mirror neuron-related Research Highlight piece in Nature Reviews Neuroscience. These Highlights pieces are written by the Editors of NRN, and are quite good, which is why I've taken to reading them ever since my free subscription started after our NRN paper appeared. Just in case the nice folks at NRN read my comment on their piece, let me clarify -- for fear they will never consider one of my papers again! :-) -- that the Highlights piece in fact accurately described the original article's position on the role of mirror neurons in complex social behaviors. In other words, the over-interpretation of the mirror-neuron data that was summarized in the NRN piece was not the editor's interpretation but the paper authors' interpretation. By the way, one of the editors at NRN is Katherine Whalley, who worked with us on our paper. She was fantastic to work with. Her editorial comments and suggestions were right on, and really helped pull the paper into shape. I wish she could help tune all of my papers!

This month's Research Highlights section has some interesting tidbits including pieces on the physiological basis of TMS (Allen et al. 2007, Science, 317:1918-21), the demonstration of resting-state neural networks in infants (Fransson, et al. 2007, PNAS, 104:15531-6), and what looks to be a very interesting computational study (Roudi & Latham 2007, PloS Comput. Biol. 3: e141) showing that the number of memories that can be stored in a neural network is smaller than previously thought. This implies that multiple networks must be employed by the brain to store large amounts of information. There's also a new review paper in the current issue by Larry Squire, John Wixted, and Robert Clark arguing that recollection and familiarity are not anatomically separated in the medial temporal lobe. Check it out!

Tuesday, November 27, 2007

The French Connection II: TalkingBrains in Paris

And in the spirit of highlighting work from other labs:

Anne-Lise Giraud and her colleagues, at the Ecole Normale Superieure in Paris, generate a steady stream of important papers. If you have not yet become a reader of her work, start now.

Anne-Lise has done important studies on speech perception, auditory perception, cochlear implants, language comprehension, and multi-sensory processing, especially voice-face interactions.

Here are a few papers, to stimulate the appetite:
  • Giraud AL, Lorenzi C, Wable J, Johnsrude IS, Frackowiak RSJ, Kleinschmidt A (2000) Representation of temporal envelope in the human auditory cortex. Journal of Neurophysiology, 84: 1588-1598.
  • Giraud AL, Price CJ. (2001) The constraints functional anatomy places on classical models of auditory word processing, Journal of Cognitive Neuroscience 13, 754-765.
  • v. Kriegstein K., Giraud AL (2004) Functionally distinct territories in the right STS for the processing of voices, Neuroimage 22, 948-55.
  • Giraud AL, Kell C, Thierfelder C, Sterzer P, Preibisch C, Kleinschmidt A. (2004) Neural substrates of speech processing: effects of sensory features, auditory search and comprehension. Cerebral Cortex 14:247-55. [see other post]
  • V Kriegstein K, Giraud AL. (2006). Implicit multisensory associations influence voice recognition. PLoS Biology.
I am a big fan of this work -- so I managed to join them in a study. Stay tuned for a French Connection III posting on a new paper, hopefully very very soon ....

The French Connection I: An important paper that Greg and I overlooked

When working on our paper for Nature Neuroscience Reviews (Hickok & Poeppel, 2007; see an early blog entry), we overlooked a terrific paper that we should have cited and the results of which we should have incorporated.

Giraud AL, Kell C, Thierfelder C, Sterzer P, Russ MO, Preibisch C, Kleinschmidt A. Contributions of sensory input, auditory search and verbal comprehension to cortical activity during speech processing. Cerebral Cortex. 2004 Mar;14(3):247-55.

Giraud and her colleagues presented participants with (i) regular sentences, (ii) broad-band speech-envelope noise signals (BBSEN), and (iii) narrow-band speech-envelope noise (NBSEN). Subjects were scanned with fMRI before a training period (only regular sentences intelligible) and after training (BBSEN intelligible, NBSEN not intelligible). BBSEN is highly intelligible after training, NBSEN remains entirely unintelligible -- see paper for details of the materials.

Anne-Lise and her colleagues were then able to separate the same physical stimulus when it could be understood (comprehension condition) versus not. This is the same intuition that forms the basis for sine-wave speech studies, some of Sophie Scott's studies, and many others (e.g. Athena Vouloumanos' experiment in J. Cog. Neuroscience).

(1) The stimulus attributes were reflected in activation in superior temporal cortex (including STS) bilaterally. (2) Natural speech compared to speech-envelope modulated noise selectively activated STS, again bilaterally. (3) Comprehension -- i.e. BBSEN after training as well as regular speech -- implicated bilateral MTG and inferior temporal areas.

So they found a convincing separation between areas principally responsible for sound analysis and areas mediating intelligible speech. Their data also enrich what the interpretation for the left STS should be. And their data show quite nicely that ventral stream areas are strikingly bilateral.

Sorry Broca-Wernicke-Lichtheim-Geschwind --- that part of lateralization is just wrong! It's much more bilateral when you look at comprehension and ventral stream contributions.

This paper is full of interesting details and discussion. If you are working on the neural basis of speech perception, language comprehension, intelligibility etc. I suggest you read this one. And -- a nice bonus -- the paper provides quite a bit of strong evidence for the model that Greg and I argued for in the 2007 paper.

Sunday, November 25, 2007

A few more ideas for our Top-10 list

I thought that readers (insofar as there are any left) would contribute some votes/ideas here, but the holiday (Thanksgiving in the US, at least) may have slowed down everyone's cortical metabolism.

To continue this Top-10 list (by the way, Greg, do we have the nerve to do the Top-10 most silly or stupid papers one has come across? I bet Bill Idsardi has the nerve ...), here are articles and books that have influenced how I think about the neural basis of language. Again, an unnecessarily small selection, it should go without saying.

David's End-of-Thanksgiving Approximately Top-10 List:

• Kutas M, Hillyard SA. (1980). Reading senseless sentences: brain potentials reflect semantic incongruity. Science 207(4427):203-5.
The birth of the N400. Hard not to be influenced by that one. In fact, this year we published our own first N400 paper, which was closely related to the original work [Sandeep Prasada, Anna Salajegheh, Anita Bowles, David Poeppel (2007). Characterising kinds and instances of kinds: ERP reflections. Language and Cognitive Processes. DOI: 10.1080/01690960701428292].

• Gallistel, C. R. (1980) The organization of action: A new synthesis. Hillsdale, N. J.: Lawrence Erlbaum Associates, Inc. [[Or, I you want a shorter piece, and inspiring about a different set of issues: Gallistel, C.R. (1998) Symbolic processes in the brain: The case of insect navigation. In D. Scarorough & S Sternberg (Eds) Methods, models and conceptual issues. Vol 4 of An invitation to cognitive science. 2nd edition (D. Osherson, General Editor) Cambridge, MA: MIT Press.]]
Randy Gallistel's work is not about psycho- or neurolinguistics; but, pound for pound, he is the best damn cognitive scientist out there. Practically every page has an idea worth considering for our own area of research.

• Marr, D. (1982). Vision: A Computational Investigation into the Human Representation and Processing of Visual Information," W.H. Freeman and Company, NY.
Marr's book and his way of thinking about problems is immensely useful for neurolinguistics. Everyone should read the first few chapters.

• Chomsky, N. (1986). Knowledge of language: its nature, origins and use, Praeger, New York.
Nooooaaaam ..... Nooooaaaam ..... The E-language/I-language distinction, among other things. Lots of great stuff. I mean, come one, who has had more key ideas??

• McCarthy RA, Warrington EK. (1988). Evidence for modality-specific meaning systems in the brain. Nature 334(6181):428-30.
Just plain cool lesion data.

• Felleman DJ, Van Essen DC. (1991). Distributed hierarchical processing in the primate cerebral cortex. Cereb Cortex 1(1):1-47.
Again, not neuroscience of language but vision -- but which contemporary study of functional anatomy is not deeply influenced by this seminal paper?

• Corina DP, Vaid J, Bellugi U. (1992). The linguistic basis of left hemisphere specialization. Science. 255(5049):1258-60.
An important contribution to our understanding of modality-independent representation.

• Osterhout L, Holcomb PJ, Swinney DA. (1994). Brain potentials elicited by garden-path sentences: evidence of the application of verb information during parsing. J Exp Psychol Learn Mem Cogn. 20(4):786-803.
The birth of the P600, although one must also acknowledge some of the Colin Brown/Peter Hagoort papers on this at about the same time.

• Salmelin R, Hari R, Lounasmaa OV, Sams M. (1994). Dynamics of brain activation during picture naming. Nature 368(6470):463-5.
A tour de force demonstration that one can use MEG to 'follow a signal through the brain,' by determining the cortical activation sequence.

• Friederici AD. (1995). The time course of syntactic activation during language processing: a model based on neuropsychological and neurophysiological data. Brain Lang. 50(3):259-81.
The most clear statement of the model that argues for structure-to-insertion-to-cleanup, a la Frazier, and developing the ELAN/LAN-N400-P600 model sequence.

• Turennout M, Hagoort P, Brown CM. (1998). Brain activity during speaking: from syntax to phonology in 40 milliseconds. Science 280(5363):572-4.
A clever study that begins to show how rapidly processing stages are likely to interact or follow one another.

*****Please comment/add/subtract suggestions. At the very least, if enough of us play this game, we can generate a pretty decent syllabus for a graduate seminar that all of us can use -- that would be a decent public service, no? ******

Tuesday, November 20, 2007

Top 10 most important/influential papers in the neuroscience of language

Just curious what folks think are the most important/influential papers or monographs in the history of brain-language research. Here's 16 prominent and generally very highly cited papers off the top of our heads (in alphabetical order). DISCLAIMER: This list was generated based on only a few minutes of thought. It is not intended to be a complete listing of important papers. If we have omitted YOUR important paper, or your personal favorite most important paper, do not take offense. DO, however click 'comment' at the bottom of this entry and tell us which papers we've failed to include, or which of the papers listed below don't belong in the Top 10!

Binder, J. R., Frost, J. A., Hammeke, T. A., Cox, R. W., Rao, S. M., & Prieto, T. (1997). Human brain language areas identified by functional magnetic resonance imaging. Journal of Neuroscience, 17, 353-362.

Broca, P. (1861). Remarques sur le siège de la faculté du langage articulé; suivies d'une observation d'aphémie (perte de la parole). Bulletins de la Société Anatomique (Paris), 6, 330-357, 398-407.

Broca, P. (1865). Sur le siège de la faculté du langage articulé. Bulletins de la Société d'Anthropologie, 6, 337-393.

Caramazza, A., & Zurif, E. B. (1976). Dissociation of algorithmic and heuristic processes in sentence comprehension: Evidence from aphasia. Brain and Language, 3, 572-582.

Damasio, H., Grabowski, T. J., Tranel, D., Hichwa, R. D., & Damasio, A. R. (1996). A neural basis for lexical retrieval. Nature, 380, 499-505.

Dell, G. S., Schwartz, M. F., Martin, N., Saffran, E. M., & Gagnon, D. A. (1997). Lexical access in aphasic and nonaphasic speakers. Psychological Review, 104, 801-838.

Friederici, A. D. (2002). Towards a neural basis of auditory sentence processing. Trends Cogn Sci, 6, 78-84.

Geschwind, N. (1965). Disconnexion syndromes in animals and man. Brain, 88, 237-294, 585-644.

Grodzinsky, Y. (2000). The neurology of syntax: Language use without Broca's area. Behavioral and Brain Sciences, 23, 1-21.

Linebarger, M. C., Schwartz, M., & Saffran, E. (1983). Sensitivity to grammatical structure in so-called agrammatic aphasics. Cognition, 13, 361-393.

Näätanen, R., Lehtokoski, A., Lennes, M., Cheour, M., Huotilainen, M., Iivonen, A., Vainio, M., Alku, P., Ilmoniemi, R. J., Kuuk, A., Allik, J., Sinkkonen, J., & Alho, K. (1997). Language-specific phoneme representations revealed by electric and magnetic brain responses. Nature, 385, 432-434.

Petersen, S. E., Fox, P. T., Posner, M. I., Mintun, M., & Raichle, M. E. (1988). Positron emission tomographic studies of the cortical anatomy of single-word processing. Nature, 331, 585-589.

Poizner, H., Klima, E. S., & Bellugi, U. (1987). What the hands reveal about the brain. Cambridge, MA: MIT Press.

Price, C. J., Wise, R. J. S., Warburton, E. A., Moore, C. J., Howard, D., Patterson, K., Frackowiak, R. S. J., & Friston, K. J. (1996). Hearing and saying: The functional neuro-anatomy of auditory word processing. Brain, 119, 919-931.

Wernicke, C. (1874/1977). Der aphasische symptomencomplex: Eine psychologische studie auf anatomischer basis. In G. H. Eggert (Ed.), Wernicke's works on aphasia: A sourcebook and review (pp. 91-145). The Hague: Mouton.

Zatorre, R. J., Evans, A. C., Meyer, E., & Gjedde, A. (1992). Lateralization of phonetic and pitch discrimination in speech processing. Science, 256, 846-849.

Friday, November 16, 2007

Speech specificity and fMRI resolution

A number of functional imaging studies have found that contrasting speech with various non-speech control stimuli eliminates vast areas of speech-responsive cortical activations; i.e., many areas are equally activated by speech and non-speech sounds. Many investigators discount these regions that are jointly activated by speech and non-speech sounds as being somehow less critical for speech. -- the primary quest being to identify The Speech Area. We have previously disagreed with this view, and the general approach, suggesting that regions that respond to non-speech sounds could still be carrying out critical speech-related computations. We further have suggested that these "non-speech specific" regions could still be speech specific if only we had the resolution to image the neural substructure.

Three years late, I discover a paper by Michael Beauchamp, Alex Martin and colleagues showing just this (Beauchamp et al. 2004, Nat Neurosci, 7:1190-2). They imaged a multisensory region of the STS using both typical fMRI resolution and higher resolution methods in a multisensory paradigm presenting auditory and/or visual stimuli. Using typical lower resolution imaging they found that the STS region showed equivalent responses to stimuli from either modality. Higher resolution imaging, however, found a patchy organization within this broader region that contained zones that were specifically responsive to one or the other sensory modality, as well as some zones that were responsive to both.

No difference doesn't always mean no difference. It sometimes means we just don't have the resolution to see the difference.

Thursday, November 15, 2007

Descended from Helmholtz, Wundt, James, and Freud: Neurogenealogy

According to, I'm an academic descendant of Hermann von Helmholtz, Wilhelm Wundt, William James, Clark Hull, and yes, that would-be saboteur of the classical model of aphasia, Sigmund Freud. What's more, the originator of the classical model, Wernicke, is a distant cousin. I'm apparently also a sibling of Michael Tarr and Martha Farah, and uncle to the likes of Sharon Thompson-Schill, Isabel Gauthier, Josh Tenenbaum and many more (from whom I never receive holiday cards, btw). These linkages are all through my post-doc advisor Stephen Pinker. My PhD advisor, Edgar Zurif, didn't even get a twig listed. I wonder if that makes this my adopted tree.

One wonders about the accuracy of these trees, but ultimately it doesn't much matter because for the most part everyone is related to everyone else, and just about everyone's lineage can be traced back to luminaries like Helmholtz and James. It's kind of like real family trees: fascinating to dig into, but once you are a couple generations removed, they're pretty much meaningless. (Did I tell you I was related to Wild Bill Hickok, and that the Hickoks came from Stratford-upon-Avon and were neighbors -- OK, well, employees actually -- of the Shakespeares? The only advantage my distant history ever brought me was that I got into the tourist-attraction cemetery where Wild Bill is buried, for free.)

For an interesting essay on the psychology and evolutionary significance of kinship and genealogy, check out Steve Pinker's recent piece in the New Republic, "Strangled by Roots."

Wednesday, November 14, 2007

SfN 2007 Virtual Poster Session

Why don't we use this forum for virtual poster sessions associated with recent conferences, starting with SfN? If you couldn't make it to SfN, or went but missed some relevant posters, or presented a poster that you'd like to continue to promote, or have a poster that you wished you could have presented, just click "comment" at the bottom of this post and provide the abstract and a URL where a pdf of your poster can be downloaded.

Tuesday, November 13, 2007

Talking Brains Down Under

Greig de Zubicaray's comment on our new survey feature reminded me to highlight the nice body of brain-language fMRI work coming from Down Under. Greig and colleagues at the University of Queensland have been pumping out an impressive number of very cool papers on lexical processing both in perception and production. The work is thoughtful, and psycholinguistically informed. A few sample citations are below. Their work is definitely worth paying attention to.
Copland DA, de Zubicaray GI, McMahon K, Eastburn M.
Neural correlates of semantic priming for ambiguous words:
an event-related fMRI study. Brain Res. 2007 Feb 2;1131(1):163-72.

de Zubicaray G, McMahon K, Eastburn M, Pringle A, Lorenz L.
Classic identity negative priming involves accessing
semantic representations in the left anterior temporal cortex.
Neuroimage. 2006 Oct 15;33(1):383-90.

de Zubicaray G, McMahon K, Eastburn M, Pringle A.
Top-down influences on lexical selection during spoken
word production: A 4T fMRI investigation of refractory
effects in picture naming.
Hum Brain Mapp. 2006 Nov;27(11):864-73.

Copland DA, de Zubicaray GI, McMahon K, Wilson SJ,
Eastburn M, Chenery HJ.
Brain activity during automatic semantic priming revealed
by event-related functional magnetic resonance imaging.
Neuroimage. 2003 Sep;20(1):302-10.

Saturday, November 10, 2007

Talking Brains mirror neuron entry referenced in German science magazine

Our Talking Brains discussion of mirror neurons was recently cited in a German science magazine, bild der wissenschaft. I have no idea what the article says, but I also recognized Alison Gopnik's name, so that's got to be good right? Check it out here.

So David, what's it say?

Friday, November 9, 2007

New survey feature!

Ok, I just discovered that we can easily add surveys to the blog, so let's try it out for fun. How do people feel about mirror neurons and speech perception? Take the survey in the right column of the blog.

SfN07 News -- No link between conduction aphasia and the arcuate fasciculus

It's not exactly news, but now we know for sure: conduction aphasia is NOT caused by damage to the arcuate fasciculus. Nina Dronkers presented data from over 100 patients at the SfN meeting showing convincingly that arcuate fascisulus damage does not cause conduction aphasia. In fact, it causes a much more serious language production deficit.

The idea of conduction aphasia resulting from damage to the arcuate fasciculus (AF) has been seriously challenged since 1980 when the Damasio's published their study of the anatomical correlates of conduction aphasia. That paper showed that conduction aphasia was often associated with left auditory cortex lesions (dorsal STG), not AF lesions. Subsequent case studies showed that damage to the AF does not cause conduction aphasia, and that conduction aphasia-like symptoms can be elicited by cortical stimulation (arguing against the disconnection theory of conduction apahsia). We reviewed some of this evidence in Hickok et al. 2000.

Nina's new study, though, is the first large scale investigation of the question, and really puts a nail in the AF-conduction aphasia coffin.

Wednesday, November 7, 2007

Accountability in the review process

Having been knee deep recently responding to both grant proposal and paper reviews (as reviewee), I find myself more and more annoyed with the review process. Sometimes, maybe even most of the time, reviews can be helpful. But we all get those off-base or nitpicky reviews that are at best a tedious annoyance or at worst, a grant killer. Anonymity and lack of public accountability for what one writes in a review, I think, gives some reviewers carte blanche to shoot from the hip, often causing collateral damage.

There's a solution: Make the reviews public.

Not that many people would read them. We've already got more than enough to read. But maybe just knowing that your off the cuff remarks might be subject to public ridicule -- on some blog, for example ;-) -- would be enough to induce a little constraint and rationality.

There are other benefits to public reviews. Sometimes reviewer-reviewee exchanges are highly instructive, and sometimes more interesting than what goes in the paper. It could be beneficial, or at least discussion-provoking, to see these behind the scenes debates. Published reviews could also cut down on work when responding to reviews: when you get the same criticism over and over again, you could just cite a previous review response rather than writing a whole new response every time ("see Hickok & Poeppel review response 2000, 2004, 2007 for repeated and thorough dismantling of the same tired point you raise here"). It might also promote more constructive criticism in reviews, or even more willingness to review papers because the reviewer would get some credit for suggesting that clever control or theoretical insight. Folks might even become so proud of their reviews that they might start signing them and listing them as pubs.

Maybe we'll start publishing reviews of our papers here. I wonder if that would cause a stir.

Tuesday, November 6, 2007

Raise your martini glass to Sylvius

News from the SfN meeting...

Q: What does the Sylvian fissure and gin have in common?
A: Both can be traced back to one Franciscus Sylvius.

According to a poster by Andre Parent of Laval University, Flemish anatomist Franciscus Sylvius (1614-1672) not only gave his name to the prominent lateral fissure, but more importantly, the dude invented gin. Apparently in an effort to develop a diuretic for the treatment of kidney disease, Sylvius mixed the oil of juniper berry with grain alcohol. The concoction became known as jenever (juniper in Dutch) and geniévre (in French). The term was eventually anglo-thrashed into the word “gin.” English soldiers brought it back to their homeland where it became wildly popular. Not sure how well it worked for kidney disease.

Monday, November 5, 2007

Anterior Temporal Lobe and Syntax

As promised, more from Richard Wise's visit to Talking Brains West...

When I asked Richard what he didn't like about our 2007 paper, his response was, our claim about the ATL involvement in syntax. I'm inclinded to agree. Here's the details.

I mentioned in a previous entry, as well as in our NRN paper, that because of the diffuse damage, semantic dementia (SD) cannot provide convincing evidence regarding what the anterior temporal lobe(s) (ATL) is(are) doing. However, it can provide fairly convincing evidence regarding what the ATL is not doing. If some function is spared despite extensive damage to the ATL bilaterally, we can conclude that the ATL is not critical for that function.

In the functional imaging literature, the ATL has emerged as a possible site involved in some form of syntactic computation because responses in this region tend to be sentence-selective. A big problem for this idea, however, is that resection of the ATL does not produce syntactic deficits or any substantial language deficits at all. This problem might be circumvented by proposing that syntactic functions are bilaterally organized in the ATL, explaining why unilateral resection doesn't impair function substantially.

Here's where SD comes in. It has been claimed that SD patients have relatively preserved syntactic ability. I never really understood how a patient could have severely impaired word comprehension with preserved syntactic ability (there's lots of syntactically relevant information in words), so I didn't view SD as strong evidence against a role for syntactic processing in the ATL. Consequently, we have claimed that the ATL may be a site for some kind of syntactic processing, despite claims emanating from the SD literature.

Back to Richard's visit: According to Dr. Wise, SD patients have no trouble with syntax, including a preserved ability to make grammaticality judgments. I believe him. While I wasn't terribly convinced by the published claim -- lots of published claims are wrong -- to hear it from a good clinician who has seen SD patients convinced me (clinical intuition is an extremely valuable research tool).

So does this mean we need to revise our views on the role of the ATL in syntactic processing. Yes, I think so. If SD patients have badly diseased ATLs bilaterally, and can still do reasonably good at the syntactic level, I think we need to rethink things. Part of this rethinking should involve (i) a clear specification of what SD patients can and cannot do syntactically (Grodzinsky, check it out for us will you?), (ii) understanding how word-level semantic deficits might impact sentence-level processing (it has to right?), and (iii) determining whether the ATL might still be involved in combinatorial semantic operations.

Friday, November 2, 2007

Macaque motherese??

Last week's Quirks and Quarks science show (from CBC radio) had a segment about Dr. Jessica Whitham's research on infant-directed vocalizations in macaques. The vocalizations share some characteristics with descriptions of human motherese (higher pitch, greater pitch range, etc.). It's not yet clear that this adds macaques in learning their vocalizations, in fact, it's not entirely clear why they do this at all, since it's apparently only directed at other macaque's infants ("Hey you kids, get out of that Jello tree!").

Link (scroll down to find the segment):

Bill Idsardi

The Intense World Syndrome

Browsing through the first set of articles on the new Frontiers in Neuroscience journal, I came across this paper:

"The Intense World Syndrome – an alternative hypothesis for autism" by Markram et al.

The basic idea is that autism spectrum disorders result from hyper-reactive and hyper-plastic neural circuits. This is in contrast to typical accounts that emphasize hypo-functionality. This seems like a much more interesting and potentially plausible account than the mirror neuron view. The paper describes evidence for their claims, derived from a rat model of autism.

Even if the hypothesis turns out to be incorrect, the authors at least deserve credit for coming up with an attention-grabbing name. It makes me think we should rename our Dual Stream Model to something bit more flashy. How about, The Galactic Double Parallel Pathway Model?

Talking Brains at Society for Neuroscience

If you are in San Diego for the SFN meeting, stop by our poster on Tuesday. I'll be there...

The neural organization of linguistic short-term memory is sensory modality-dependent: Evidence from signed and spoken language
San Diego Convention Center: Halls B-H
Presentation Start/End Time:
Tuesday, Nov 06, 2007, 2:00 PM - 3:00 PM
1Univ. California-Irvine, Irvine, CA; 2The Salk Inst. for Biol. Sci., San Diego, CA
Despite decades of research, there is still disagreement regarding the nature of the information that is maintained in linguistic short-term memory (STM). Some authors argue for specifically phonological codes, whereas others argue for more general sensory traces. We test these hypotheses by investigating linguistic STM in two distinct sensory-motor modalities, signed and spoken language. Hearing bilingual participants (native in English and American Sign Language) performed equivalent STM tasks in both languages during fMRI scanning. Distinct, sensory-specific activations were seen during the maintenance phase of the task for spoken versus signed language. These regions have been shown previously to respond also to non-linguistic sensory stimulation, suggesting that linguistic STM tasks recruit sensory-specific networks. However, maintenance-phase activations common to the two languages were also observed. We conclude that linguistic STM involves both sensory-dependent and sensory-independent neural networks, and further propose that STM may be supported by multiple, parallel circuits.

Thursday, November 1, 2007

Richard Wise visits TalkingBrains West

Had a nice visit with Richard Wise yesterday. We are long time fans of Richard's work and share a number of theoretical views with him, such as bilateral organization of speech recognition and sensory-motor integration in the auditory dorsal stream. We have friendly disagreements on a few points as well, specifically the relative role of anterior vs. posterior temporal lobe areas in lexical-semantic aspects of language processing.

Richard views the anterior temporal lobe as a critical site for lexical-semantic processing, based largely on evidence from semantic dementia, whereas we are more impressed by the stroke data showing impairments of auditory comprehension and production following left posterior temporal lesions as is often found in Wernicke's aphasia. We have discounted semantic dementia data because the disease, while most severe in ATL areas, is nonetheless quite diffuse and therefore one cannot link ATL damage to lexical-semantic impairments with confidence. Richard has discounted the stroke data by (correctly) pointing out that strokes can disrupt function not only at the site of tissue loss, but also in distal sites by disrupting functional connectivity.

Of course we discussed this issue yesterday, and here was the outcome:

1. We agree on the data, and each acknowledge the feasibility of the counterarguments (diffuse damage in semantic dementia and remote effects of stroke).

2. We still disagree on the relative importance of these sources of data.

3. But, as Richard put it nicely, when reasonable people have legitimate disagreements it probably means both are right to some extent. So I suppose the disagreement has weakened into one of degrees: I would argue that while both anterior and posterior areas are involved, the posterior regions are more important, whereas Richard would view the anterior areas as more important. Of course, both of us are ignoring the likely contributions of frontal areas...

4. We both agree strongly that whatever the ATL is doing, it's doing it bilaterally. Unilateral resection of the left or right ATL does not produce semantic dementia, and while atrophy in semantic dementia is often greater on the left, the disease affects the ATL in both hemispheres (as well as several other areas including medial temporal lobe). The best explanation of these data is that bilateral disruption is accounting for the severity of the deficit in semantic dementia. The rumor is that another group has done a TMS study disrupting function in the ATL bilaterally. Could be interesting.

More on Richard's visit to follow...