Tuesday, November 25, 2008

The Neuro-Cognitive Rehabilitation Research Network

The Neuro-Cognitive Rehabilitation Research Network (NCRRN) is a valuable resource that is worth checking out. In their own words:

This NCRRN is a collaborative effort of investigators at the Moss Rehabilitation Research Institute and the University of Pennsylvania to provide research infrastructure support and expert consultation to individuals interested in pursuing cognitive rehabilitation research.

On the site, you will find announcements for presentations and events, assessment tools like the PNT, as well as information on grants for pilot project in topics related to neuro-cognitive rehab.

Check it out!

Thursday, November 20, 2008

Here's a review ...

OK, here's my favorite recent review, in response to a MEG paper by a post-doc in my lab, Mary Howard:

"The results presented clearly support the proposed model. Procedure and ... analysis ... technically correct and include some sophisticated details. Moreover, the ms. is well written and exceptionally well illustrated."

Result: outright rejection, with no possibility to 'reject the rejection' (my favorite activity). The other reviewer thought the idea was "timely and important," but not enough so, I guess :-(

Ugh! In that case, I'd rather have the brutal rejections like "your entire career is worthless; every piece of research you have touched is wrong; you're hurting the field; incoherent" and so on. 

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.

Monday, November 17, 2008

Jeff Binder visits Talking Brains West

I recently had the pleasure of hosting Jeff Binder during his visit to our Center for Cognitive Neuroscience here at UC Irvine. Jeff, of course, was among the first to use fMRI to study the auditory system and has published several important papers in the field. I had met Jeff before at conferences, and had many previous email correspondences, but never had the chance previously to hang out and chat, so it was a fun visit.

His talk was on the neural basis of semantics -- not action semantics, or the semantics of fruits and vegetables, just semantics, broadly construed. Not to steal his thunder when the work eventually gets published but... He presented a meta-analysis of a boatload of imaging studies on "semantic processing." Lots of different kinds of stimuli and tasks were included in the meta-analysis, so the findings are necessarily going to be relevant to a very broad definition of semantics. I can imagine someone critiquing the approach based on this loose definition of semantics, and in one sense I wouldn't disagree: the analysis isn't going to tell you anything about the details of semantic representation or processing. On the other hand, I personally found it very useful as a guide to distribution of brain regions involved in semantic processing. And guess what? It wasn't just motor cortex, or the anterior temporal lobe, or the posterior temporal lobe, or the angular gyrus that was involved. It was a fairly extensive distribution of regions that included many of these "semantic" areas and more. (We'll have to wait for the paper to get the details -- my memory isn't that good.) One thing I found particularly interesting was that the distribution of these semantic areas was virtually identical to the distribution of the "default network" -- the set of brain areas that seem to show increased activity during "rest" periods in functional imaging studies (i.e., when subjects are thinking about any number of things they're not supposed to be thinking about). This, of course, has important implications for how we design our experiments because the resting baseline is really more like a contrasting our task of interest with a semantic task.

Thanks to Jeff for a fun and informative visit!

Friday, November 14, 2008

Publishing manuscript reviews

Well, we have a split vote on the question of whether publishing one's manuscript reviews is an ethical practice or not: 48% say YES, 40% say NO, and 11% say NOT SURE. I personally don't think it is unethical (see Mary Louise Kean's arguments, for example). It may be uncool in some circumstances, but many reviews are also very uncool...

Nonetheless, I'm not going to post the reviews of my mirror neuron critique paper. The good news is, though, that the paper is now accepted and should be appearing soon in Journal of Cognitive Neuroscience. A reviewer of the paper was invited to write a rebuttal paper. I hope s/he does. It will be interested to have a public discussion on the issues.

But back to publishing reviews. Just this week I got another nasty review back on another paper, this one related to the hypothesized sensory-motor response properties of area Spt. We have been plugging away for some years now trying to pin down the response properties of Spt and exploring the similarity of this region with sensory-motor integration regions in the posterior parietal lobe. I had listed the range of findings that show parallels between Spt and parietal lobe areas. Here's a comment about our hypothesis from the reviewer:

The analogy with the inferior parietal lobule is not well supported, and its use in framing the arguments of the paper is based on a number of vague assumptions, over-generalizations, and idiosyncratic inferences about the brain that derive from studies produced virtually exclusively in the authors' laboratory.

(Oops. Did I just publish part of a review?)

We of course apologized profusely for citing our own empirical work, which is clearly inappropriate and should be strictly prohibited in scholarly publications. We make no apologies, however, for being vague, idosyncratic, over-generalizers.

So how about we start a Top Ten list of nasty review excerpts? It might be kind of entertaining. I've got two on the board already. Send them to me offline or as a comment.

Friday, November 7, 2008

More info on the Auditory Cognitive Neuroscience Society Meeting

ACNS 2009 Tucson, AZ
Integrated Learning Center (ILC) on the University of Arizona campus
Room TBA

The University of Arizona will be hosting the 3rd annual Auditory Cognitive Neuroscience Society (ACNS, formerly ACSS) conference on January 9-10, 2009. The conference (co-organized by U of A and Arizona State University) will be a two-day event, taking place on Friday and Saturday. The conference is FREE and open to all!

Invited Speakers include Doctors:
- Tom Christensen, University of Arizona
- Michael Dorman, Arizona State University
- Greg Hickok, University of California-Irvine
- Lori Holt, Carnegie Mellon University
- Julie Liss, Arizona State University
- Andrew Lotto, University of Arizona
- Bob Lutfi, University of Wisconsin-Madison
- Edwin Maas, University of Arizona
- Andrea Pittman, Arizona State University
- Brad Story, University of Arizona
- Arty Samuel, State University of New York-Stony Brook
- Lynne Werner, University of Washington
- Bill Yost, Arizona State University

Topics to be discussed include the perceptual/cognitive/motor foundations of child speech development, a comparison of audition and vision, and the processes and constraints in auditory learning. Each session will conclude with a group discussion or more aptly put, a period of time to “shoot your mouth off.”

Posters: If you are interested in submitting a poster abstract, please see the guidelines provided below or visit the ACNS 2009 Meeting Webpage for a link to a printable version.

ACNS 2009 Abstract Submission Guidelines

This year we will be accepting a limited number of posters to be displayed during the ACNS Conference. Acceptance criteria include the following:
The research to be presented is pertinent to the domain of Auditory Cognitive Neuroscience.
The methodology of the work is sound.
Work in progress will be in presentable form by the time of the conference.

Abstracts should be no longer than 350 words (not inclusive of graphs, figures, or references) and include the following components:
Statement of the Problem
Study Design and Method
Results and Interpretation

Please email abstracts, including author names and affiliations, to julie.liss@asu.edu no later than Monday December 1st, 2008. Details regarding poster size and format will be provided at the time of acceptance notification.

Registration: We will be asking those who plan to attend this year’s conference to RSVP on our new registration page (link soon to come on the ACNS Webpage!). Attendee numbers are necessary in order for us to reserve rooms at local hotels. Please note that CEUs will no longer be offered to ACNS conference attendees.

Hope to see you in January!
Andrew Lotto & Julie Liss

Tuesday, November 4, 2008

Mirror neurons in humans revealed by fMRI adaptation

Riitta Salmelin alerted me to this study which used an fMRI adaptation paradigm to identify mirror neurons in the human brain. Mirror neurons have previously been assumed to exist in humans, but without direct evidence. Here is the abstract for the paper, FYI:

Chong, T. T., R. Cunnington, et al. (2008). "FMRI adaptation reveals mirror neurons in human inferior parietal cortex." Curr Biol 18(20): 1576-80.
Mirror neurons, as originally described in the macaque, have two defining properties [1, 2]: They respond specifically to a particular action (e.g., bringing an object to the mouth), and they produce their action-specific responses independent of whether the monkey executes the action or passively observes a conspecific performing the same action. In humans, action observation and action execution engage a network of frontal, parietal, and temporal areas. However, it is unclear whether
these responses reflect the activity of a single population that represents both observed and executed actions in a common neural code or the activity of distinct but overlapping populations of exclusively perceptual and motor neurons [3]. Here, we used fMRI adaptation to show that the right inferior parietal lobe (IPL) responds independently to specific actions regardless of whether they are observed or executed. Specifically, responses in the right IPL were attenuated when participants observed a recently executed action relative to one that had not previously been performed. This adaptation across action and perception demonstrates that the right IPL responds selectively to the motoric and perceptual representations of actions and is the first evidence for a neural response in humans that shows both defining properties of mirror neurons

This is a very cool and cleverly designed study. Basically, they were looking for areas that showed adaptation (decreased BOLD amplitude) for observed actions that followed the same executed actions relative to observed actions that were not previously executed. Here is the result:

They observed adaption in one of their ROIs in the right parietal lobe (ROIs included IFG, IPL, and STS). If you buy the adaptation logic -- it seems reasonable to me -- this means that mirror neurons live in the right parietal lobe of humans. So we finally have some direct evidence for the existence of mirror neurons in humans. Cool. I knew someday we'd have decent evidence. It is surprising, though, that no mirror neurons were found in the frontal lobe or the left hemisphere (where damage can lead to disorders of action production and recognition), but let's not get bogged down in details.

A couple of points are relevant. One is that if this result holds, it means that human mirror neurons and monkey mirror neurons are different. Chong et al. used pantomimed gestures. Classic F5 mirror neurons don't respond to pantomime. In effect, we have a new animal that needs to be studied in its own right. Who knows, maybe the function of these human mirror neurons are completely different! Another relevant point is that just because some form of mirror neuron exists in humans doesn't mean that this system supports action understanding. The Chong et al. study has nothing to say about this question. So all previous critiques of the action understanding portion of the mirror neuron doctrine still hold.

T CHONG, R CUNNINGTON, M WILLIAMS, N KANWISHER, J MATTINGLEY (2008). fMRI Adaptation Reveals Mirror Neurons in Human Inferior Parietal Cortex Current Biology, 18 (20), 1576-1580 DOI: 10.1016/j.cub.2008.08.068

Monday, November 3, 2008

Ventral premotor cortex and action processing: Urgesi, et al.

Here is another pair of studies that a reviewer suggested I failed to discuss because they didn't support my pre-conceived hypothesis regarding mirror neurons. It's true that I didn't discuss them, but not because I cherry picked papers to discuss. I simply wasn't aware of these. After looking at them, I realized that they did not even test action understanding, so I could have justified leaving them out. Nonetheless, because they apparently are viewed a strong evidence for the link between the ventral premotor cortex and action processing, I included a discussion in my review. Here is a summary...

Urgesi et al. (2007a/2007b) used rTMS to study the effects of functional deactivation of ventral premotor cortex (vPMc) on visual discrimination of action-related pictures In both of these studies, subjects were asked to make two-choice, match-to-sample judgments: a picture of a body configuration was presented (the sample) followed by a mask (500msec), and then a picture of two body configurations; the subject was asked to indicate which of the two matched the sample.

First, as I mentioned above, it is important to notice that neither of these studies actually tested action understanding. That is, discrimination performance did not depend on understanding the meaning of the actions, and could be performed based on configural information alone.

Urgesi, Candidi et al. (2007) compared the effects of stimulation of vPMc with stimulation of a ventral temporal-occipital location (the extrastriate body area, EBA) during action discrimination (which action matches the sample?) versus form discrimination (which actor matches the sample, independent of action?).

For action judgments vPMc stimulation yielded longer reaction times than EBA stimulation, and the reverse held for form judgments, longer reaction times for EBA stimulation than vPMc stimulation. Stimulation had no effect on accuracy. In the other study (Urgesi, Calvo-Merino et al., 2007), subjects were asked to judge body configuration only, and an effect of accuracy was observed with vPMc stimulation associated with more errors on the configuration matching task than with EBA stimulation. Oddly, there were no reaction time effects.

So the two studies showed that interference stimulation to vPMc negatively affected performance on a body configuration delayed matched-to-sample task. Again, because these studies did not assess action understanding, they cannot speak to the question of whether the mirror system supports action understanding. However, they do suggest that processing of body configurations at least in the delayed match-to-sample task involves vPMc to some extent. Given that the tasks involved working memory, it seems possible that this region may support some sort of working memory for body configurations. This is interesting, but in my view is more consistent the idea that the "mirror system" is a sensory-motor integration system, not a semantic system. For example, there are many claims regarding the sensory-motor nature of working memory systems (Buchsbaum & D'Esposito, 2008; Hickok, Buchsbaum, Humphries, & Muftuler, 2003; Pa, Wilson, Pickell, Bellugi, & Hickok, in press; Postle, 2006; Ruchkin et al., 2003; Wilson, 2001).

Cosimo Urgesi, Matteo Candidi, Silvio Ionta, Salvatore M Aglioti (2006). Representation of body identity and body actions in extrastriate body area and ventral premotor cortex Nature Neuroscience, 10 (1), 30-31 DOI: 10.1038/nn1815

C. Urgesi, B. Calvo-Merino, P. Haggard, S. M. Aglioti (2007). Transcranial Magnetic Stimulation Reveals Two Cortical Pathways for Visual Body Processing Journal of Neuroscience, 27 (30), 8023-8030 DOI: 10.1523/JNEUROSCI.0789-07.2007