Monday, January 31, 2011

Why is Broca's area active during speech perception?

A now-common finding in the functional imaging literature on speech perception is that Broca's area is active during the perception of speech. The activation magnitude is sometimes not as strong or consistent as one finds in auditory cortex, but it is there and so requires some explanation. There are a few possibilities. (I'm talking about Broca's area as if it were one functional region, which it isn't, but we'll gloss over that for now.)

1. Broca's area drives the analysis of speech sounds (i.e., the motor theory of speech perception is correct).
2. Broca's area supports/modulates the analysis of speech sounds via some predictive coding process (articulation driven forward model or analysis by synthesis).
3. Broca's area activation is epiphenomenal -- it simply reflects spreading activation in association networks and serves no function in speech perception.
4. Broca's area activity reflects a higher-order process (e.g., cognitive control) that is involved in say, response selection.

We can quickly rule out #1 for reasons that have been articulated previously, e.g., here.

Regarding the other possibilities, I think the question is still open for debate. As additional fuel for this debate, consider the following recently published (epub-online) finding reported by Vaden et al.

In an fMRI study, listeners heard sets of words that varied in terms of phonotactic probability, which is a measure argued to reflect sublexical properties of words (density was also manipulated but didn't show a robust effect). The task was to monitor for occasional non-words embedded in the word sets -- these trials were excluded from analysis. The goal was to try to identify neural regions that are sensitive to sublexical properties of words.

One might have expected to find such effects in relatively early stages of processing in auditory cortex, based on the standard hierarchical assumption that word recognition first analyses segmental-level information which it then uses to access the appropriate lexical-phonological codes, generally acknowledged to be coded/processed in the STS. However, Vaden et al. found no effects in auditory cortex, indeed in the entire temporal lobe. Instead, activation in Broca's area (~pars opercularis) was modulated as a function of phonotactic frequency: word sets comprised of higher phonotactic frequency words yielded greater activity in Broca's area. What's interesting about this is subjects have no conscious idea that the words vary according to frequency of the sounds sequences that comprise them, yet Broca's area sure does.

So what's up? Does this mean that the motor theory is right? Is Broca's area critically involved in the early analysis of speech information? Nope. (Refer again to the reasons why #1 above can't be right.) It must be something else.

Cognitive control? Subjects were trying to find occasional non-words. Maybe phonotactic modulations vary cognitive decision load... This is possible but not likely: no effect in Broca's area was found for neighborhood density, which is argued specifically to induce competition and therefore should affect decision processes. Further, cognitive control effects tend to involve more anterior regions.

Forward prediction? Yes, possibly. High phonotactic frequency items are associated with more predictability. Maybe Broca's area gets excited when it encounters a predictable pattern.

Epiphenominal? Yes, possibly. High phonotactic frequency items likely have stronger associations between auditory and motor representations of speech; the stronger the association, the more spreading activation one sees.

Here's what I really think is going on. Basically, the strength of the association between auditory and motor representations of a phonemic sequence is what's driving the correlation, as in the epiphenominal account. Why do these associations exist? Because the goal of speech production is to reproduce a particular *sound*. To achieve this production task we need to relate sound and movement. Those auditory-motor codes that are more frequent are more strongly associated leading to more activation. HOWEVER, even though the underlying explanation for this effect has more to do with speech production than speech perception, it may be possible for the speech system to take advantage of the situation and use this information to augment perception, in a forward predictive manner.

Returning to the question of hierarchical models of word recognition, it is interesting that no such effects of phonotactic probability showed up in auditory regions. This is consistent with the view that speech recognition does not necessarily involve access to segmental level units. But it could also be that phonotactic probability isn't a good metric of segmental level processing.


Vaden, K., Piquado, T., & Hickok, G. (2011). Sublexical Properties of Spoken Words Modulate Activity in Broca's Area but Not Superior Temporal Cortex: Implications for Models of Speech Recognition Journal of Cognitive Neuroscience, 1-10 DOI: 10.1162/jocn.2011.21620


Call for SYMPOSIA,


Basque Center on Cognition, Brain and Language.
Donostia-San Sebastián

September 29th – October 2nd 2011


Cathy Price. University College London, UK
Robert Zatorre. McGill University, Quebec, Canada
The Broadbent lecture: Randi Martin. Rice University. USA
The Bertelson award: Antonino Vallesi. SISSA. Italy

"Pintxos on my mind: When gastronomy meets cognitive psychology"

Invited speaker: Dana Small. Yale University, USA.
Invited chefs: Andoni Aduriz, Eneko Atxa and Juan Mari Arzak


At this point we welcome submissions of symposia on topics related with Cognitive Psychology and neighbor areas.

Symposia can now be submitted electronically, and must be submitted by the
deadline of March 1st, 2011. They will be reviewed anonymously by expert reviewers, and authors will be notified with decisions by March 15th, 2011.

Wednesday, January 26, 2011

On the relation between auditory-motor area Spt and conduction aphasia

Conduction aphasia is characterized by relatively frequent phonemic speech errors with self-correction attempts and difficulty repeating speech verbatim; comprehension is relatively well-preserved. The classical account holds that conduction aphasia is caused by damage to the arcuate fasciculus. However, we have been arguing for some time that conduction aphasia is caused by damage to area Spt -- a functionally defined region in the vicinity of the left planum temporale that exhibits auditory-motor response properties, and which we claim computes a mapping between auditory and motor speech representations, critical for aspects of speech production.

Our hypothesized link between conduction aphasia and area Spt just got stronger. In a forthcoming paper in Brain and Language Buchsbaum et al. show that the region of maximal overlap in lesion distribution of a group of 14 conduction aphasics includes area Spt (based on fMRI data from over 100 participants).

We argue that the auditory-motor transformation function carried out by Spt is necessary for verbatim repetition but also plays a critical role in internal monitoring during speech production, thus explaining the increased speech error rate when the system is damaged. This explanation does a better job of explaining the co-occurrence of phonemic paraphasias and repetition deficits than does the current dominant model of the deficit in conduction aphasia, namely, that it is a working memory deficit.


Buchsbaum BR, Baldo J, Okada K, Berman KF, Dronkers N, D'Esposito M, & Hickok G (2011). Conduction aphasia, sensory-motor integration, and phonological short-term memory - An aggregate analysis of lesion and fMRI data. Brain and language PMID: 21256582

Baldo, J.V., Klostermann, E.C., and Dronkers, N.F. (2008). It's either a cook or a baker: patients with conduction aphasia get the gist but lose the trace. Brain Lang 105, 134-140.

Hickok, G., Buchsbaum, B., Humphries, C., and Muftuler, T. (2003). Auditory-motor interaction revealed by fMRI: Speech, music, and working memory in area Spt. Journal of Cognitive Neuroscience 15, 673-682.

Hickok, G., Erhard, P., Kassubek, J., Helms-Tillery, A.K., Naeve-Velguth, S., Strupp, J.P., Strick, P.L., and Ugurbil, K. (2000). A functional magnetic resonance imaging study of the role of left posterior superior temporal gyrus in speech production: implications for the explanation of conduction aphasia. Neuroscience Letters 287, 156-160.

Hickok, G., Okada, K., and Serences, J.T. (2009). Area Spt in the human planum temporale supports sensory-motor integration for speech processing. J Neurophysiol 101, 2725-2732.

Lab Manager position UC Irvine -- Hickok Lab

Position: Specialist Series (Junior, Assistant, or Associate)
The Department of Cognitive Sciences announces a Specialist position at the junior, assistant or associate level (depending on experience) in the field of Neurobiology of Language. The specialist will be involved in coordinating multiple projects which will involve distributing and standardizing the administration of behavioral assessments, compiling and managing databases from a variety of sources, managing human subjects procedures (e.g., recruitment, subject database management, administrating Institutional Review Board applications), performing basic data analysis, and assisting in speech/language test development.

Initial appointment is for one year at up to 100% effort. Renewal and percent effort is based on performance and availability of grant support. Salary will be commensurate with experience.

Requirements: Bachelor’s degree is required. Post-graduate training is preferred. Strong organizational, management, and communication skills are required, as are demonstrated and solid skills in database management, basic computer skills (Word, Excel, Powerpoint, Windows and Mac platforms), and basic data analysis skills (statistical packages). Familiarity with linguistics, psychology, and clinically-oriented research/settings is desired.

Application Procedure: Please send a letter of application and curriculum vitae to:

Lisette Isenberg
Department of Cognitive Sciences
University of California, Irvine
Irvine, CA 92697-5100

The University of California, Irvine is an equal opportunity employer committed to excellence through diversity.

NLC2011 debates and keynote addresses

We are planning the program for the next Neurobiology of Language Conference. Who would you like to see in the debate forum? Who would you like to see for keynote speakers?

Tuesday, January 25, 2011

Post doctoral opportunities -- UC Irvine, Steve Small Lab

From Steve Small...

Dear Colleague,

As many of you know, I have recently moved from The University of Chicago to the University of California, Irvine, and along with Dr. Ana Solodkin, am rebuilding the laboratory to continue the study of the fundamental neurobiology of language as well as the systems neuroscience of stroke recovery, with special emphasis on mathematical and computational modeling of imaging and physiological data.

We are in need of promising junior scientists interested in either one of these areas. In neurobiology of language, any strong candidate with serious interest in fundamental neuroscience questions about language, including (but not restricted to) comprehension, production, lexical semantics, sentential semantics, syntax, phonology, motor function, or effects in aging or aphasia, is encouraged to apply.

In stroke recovery, neural plasticity, and neural repair, we are particularly seeking candidates with strong backgrounds in applied mathematics, such as physics, mathematics, biomedical engineering, electrical engineering, and related fields, but also a strong interest in neuroscience. This work involves building computer models of human brain function, as measured by a variety of techniques, aiming at prediction of recovery, choice of therapy, and related questions. This work is highly linked to our international collaboration with the Brain Network Recovery Group.

All work involves using functional MRI, DTI, event-related EEG, sleep EEG, and/or TMS to study the human brain and to uncover the underlying mechanisms of neural processing of language and/or motor systems in health and disease. These positions are funded by a combination of the National Institutes of Health, the McDonnell Foundation, the University of California, Irvine, and/or other funds. Of course, candidates with independent funding will be given special consideration.

Please ask promising candidates to contact me directly with a CV and an informal statement of interest. Please let others in your Department and/or Institution know of these opportunities. Start dates for these positions are negotiable, although preference will be given to earlier dates.


Best regards,


Steven L. Small, Ph.D., M.D.
Professor and Chair
Department of Neurology

Professor Emeritus of Neurology and Psychology
The University of Chicago

Main Office and Mailing Address:
Department of Neurology
101 The City Drive South
Building 53, Room 204
Orange CA 92868-3201
+1-714-456-7352 (main)
+1-714-456-1697 (fax)

Laboratory and Research Office:
Room 3226
Biological Sciences III
Irvine CA 92697-4545

Wednesday, January 19, 2011

Should peer reviewers be paid for their work?

We'd all like our papers reviewed in a timely fashion by competent, thoughtful, and constructive reviewers. Needless to say, this doesn't always happen and it is easy to blame editors or journal policies for sluggish or unenlightened feedback on our journal submissions. While I don't like the policies of some journals/editors -- e.g., the policy of some journals to reject if any of the reviews are even just a nudge less than positive -- I can tell you as an editor, that the problem is most often the fault of the reviewers, i.e., you and me, the very people who complain about the peer review process.

Reviewing a paper is tedious, time-consuming, and generally thankless. Many of us get several review requests a month (or a week!). If you tend to review quickly and/or competently, you are more likely to get targeted for further review requests. So what do we do? We decline to review. As an author submitting a paper for review, we often think that the paper is "in review" basically from the moment of its submission. Sometimes it is possible to find reviewers within a day or two. Sometimes though, it can take weeks to find reviewers, especially if prospective reviewers don't respond to the original request for several days, or at all. For some papers I've edited, I've had to contact up to a dozen people before finally getting two reviewers to agree. Once in a while, I'd get a review back from one reviewer before I even find a second reviewer to agree to review the paper!

Then there is the delay in actually getting the reviews back. Most people are punctual, but certainly not all. If it takes a few iterations of review invitations to find reviewers and then one of the reviews is delayed, this can add up to substantial delays in response to the author even for journals that strive for rapid turn arounds.

Who ends up reviewing your paper? Well, in many cases it is junior scientists. Senior folks in the field tend to be more crunched for time and receive far more review requests. The people who end up agreeing to review (often via referrals from the first choice scientists) are more junior who have more time and more to gain (you get to add it to your CV!). Many junior scientists provide excellent reviews, but lack of experience and the broader perspective that comes with it can lead to weak reviews in various ways. This is the source of at least some of those slightly misinformed reviews we've all received.

So what can we do? For starters, I think it helps to realize that *we* are part of the problem. Next time you get frustrated with journal turnaround time, think twice about declining that next review invitation. A simple thing we all can do is respond quickly to review requests, even if it is to decline, and provide thoughtful alternative suggestions for other reviewers.

Some journals have instituted a reward system for reviewers, for example, if your review is on time you get entered into a lottery to win a prize. I don't find this particularly motivating though. Frontiers journals have an interesting policy: for every paper that comes in, every review editor (the editorial board, which is generally large for these journals) gets an invitation to review the paper. This seems to work because every time I click my response to these review requests, I get a message saying that the required number of reviewers has been found. Maybe this approach would work more generally. It is annoying to get this constant flood of invitations though, and pretty soon you realize it is easier to say 'no thanks' when you know there is a large pool of reviewers who received the request.

So what about paying reviewers? Would you be more willing to review a paper if you were paid $50 or $100 (if it was submitted on time of course!)? NIH pays grant reviewers to help offset the time commitment and effort. Why shouldn't journals pay too? Maybe they can't afford to, but they could impose a submission fee that would cover the cost of reviewer payment. Would you be willing to pay to have your paper reviewed?

What are your thoughts?

Neuroscience of Communicative Meaning summerschool, Utrecht, June 2011

Neuroscience of Communicative Meaning summerschool, Utrecht, June 6 - June 10, 2011

A one-week summerschool on the cognitive neuroscience of communicative meaning will be held in Utrecht, The Netherlands, June 6-10 this year. The summerschool aims at advanced PhD students and beginning postdocs working on this topic, and features Liina Pylkkänen, Ira Noveck, Evelyn Ferstl, Friedemann Pulvermuller, and Ivan Toni as tutors. Deadline for applications is March 1, 2011.

Practical information about the detailed program and how to apply can be found here:

The summerschool is organized by Jos van Berkum (Utrecht University, Faculty of Humanities, UiL-OTS) and Gün Semin (Utrecht University, Faculty of Social Sciences), with funding from The Neuroscience and Cognition Utrecht program.

We apologize for multiple postings.