Wednesday, September 1, 2010

More work needed

Over at Talking Brains there is an ongoing debate about whether language researchers in cognitive neuroscience are making enough progress. Fedorenko and Kanwisher think that "more work is needed", and that the answer is functional localizers. And they want to help. It's all very magnanimous.

Surely, though, there was never a greater scientific truism than the statement "more work is needed"! According to Karl Popper, more work is always needed, forever, in perpetuity. The scientific process is an inherently Sisyphean enterprise. We're doomed to be forever wrong, with probability = 1.

But of course Fedorenko and Kanwisher are right: more work is needed in the cognitive neuroscience of language. Nevertheless, I welcome you to read their remarks, because it seemed to me that there was also the implication that in two particular areas of study, namely theory-of-mind and the ventral visual stream, there is perhaps a somewhat less urgent need for more work:

"Several regions in the ventral visual stream have been shown to be exquisitely specialized for processing visual stimuli of a particular class (see e.g., Kanwisher, 2010, PNAS, for a recent overview). Furthermore, Saxe and colleagues have shown that a region in the right temporo-parietal junction selectively responds to stimuli that require us to think about what another person is thinking (e.g., Saxe & Powell, 2006, Psych Sci, and many other papers; see the publications section on the SaxeLab’s website: "

Surely if there were anything that was almost as good as scientifically true, verified, incontrovertible, consensus-worthy, etc. -- it would be that the fusiform face area (FFA in the fusiform gyrus) and the theory-of-mind area (TPJ in the right temporo-parietal junction) are 100% functionally specialized. Here, try this out. Next time you're at a neuroscience conference, out to dinner with a diverse assortment of your cleverest colleagues, stand up and say loudly and earnestly that you know with as much certainty as you know anything in this world that the right TPJ functions to "let one know what others are thinking" and that it only functions to "let one know what others are thinking". Add that it has been "demonstrated beyond any doubt". Then finish off the thought by saying: "No more work needed. It's a wrap". I promise that everyone will nod in vigorous -- in violent and perhaps even hysterical -- agreement.

OK, one caveat. Make sure Professor Jason Mitchell is not in attendance. Because he authored a paper in 2008 published in Cerebral Cortex entitled:

Activity in the right temporo-parietal junction is not selective for theory-of-mind

He also wrote this (2009, Philos Trans Royal Society):

"Intriguingly, the same pattern of medial frontal, temporo-parietal and medial parietal activity consistently accompanies a number of disparate tasks that, at first blush, appear to share little in common with mentalizing. Most notably, these regions are engaged by attempts to prospectively imagine the future or to retrospectively remember the past (Addis et al. 2007; Buckner & Carroll 2007; Schacter et al. 2007; Spreng et al. in press). For example, Addis et al. asked participants alternately to imagine their future self experiencing a specific event (cued by an object, such as ‘dress’) or to recall an actual event that occurred in their past. Both prospection and episodic memory engaged a highly overlapping network of regions that included MPFC, bilateral TPJ and medial parietal cortex. In addition, the same network has also been argued to play a role in spatial navigation (Buckner & Carroll 2007; Spreng et al. in press)."

Could it be that the TPJ does a whole bunch of things, indeed -- that the TPJ is a veritable Johannes Factotum, a cognitive dilettante flitting about from task to task, engaged in all manner of cognitive processes, and lending its functional activation about with a cavalier and unsophisticated disregard for the tenets of domain specificity? It seems that there is considerable evidence that this may be the case.

More from Professor Mitchell, same 2009 review:

"The fact that prospection, episodic memory, spatial navigation and mentalizing each draws on the same set of brain regions suggests that each likewise draws on a common set of cognitive processes. What cognitive challenge might these four disparate tasks share? One answer to this question is that each requires perceivers to conjure up a world other than the one that they currently inhabit: prospection obliges perceivers to imagine possible future scenarios; episodic memory relies on the reconstruction of bygone events; and spatial navigation often includes simulations of possible routes between locations. In other words, prospection and episodic memory can be conceived of as forms of mental time travel, and spatial navigation as a form of mental teleportation, all of which depend critically on the ability to project oneself outside of the here and now, imagining times or locations other than the one currently being experienced (Suddendorf & Corballis 2007)."

OK, I should also warn that you might also want to make sure that Drs Grit Hein and Robert Knight are not in attendance when you announce that the TPJ is the theory-of-mind region and that the TPJ is only the theory-of-mind region. Because they wrote a paper entitled: "Superior Temporal Sulcus, It's my area or is it?" in the Journal of Cognitive Neuroscience (2008). Here's an interesting quote:

"Activity in the 'ToM regions' in posterior STS, intersecting the parietal lobe, also correlated with differential effects in attentional reorienting. In line with our findings, this argues against distinct functional subregions in the STS and adjacent cortices and is more in favor of the assumption that the same STS region can serve different cognitive functions, as a flexible component in networks with other brain regions. There is abundant evidence for this proposition from neuroanatomical studies revealing bidirectional connections of the STS region with a variety of brain structures, such as the ventral and medial frontal cortex, lateral prefrontal and premotor areas, the parietal cortex, and mesial temporal regions (Seltzer & Pandya, 1989a, 1994)."

In line with the network assumption, four of the five
studies in the ‘‘ ToM’’ category (Kobayashi et al., 2007; Voellm et al., 2006; Takahashi et al., 2004; Gallagher et al., 2000) report medial prefrontal activity together with STS activation, whereas STS activity in speech pro cessing was more accompanied by inferior frontal activation (Uppenkamp, Johnsrude, Norris, Marslen-Wilson, & Patterson, 2006; Rimol, Specht, Weis, Savoy, & Hugdahl, 2005). This might imply that the STS serves ToM when coactivated with medial prefrontal regions, while being
involved in speech processing when coactivated with the inferior frontal cortex."

Let me conclude by saying I'm a huge fan of cognitive neuroscience researchers advancing strong theories about the function(s) of a brain area. I have written previously that that the way forward is to embed our function terms in our structural ones -- to link them up. I have written with Mark D'Esposito a most thorough and plaintive hymn on the (quixotic?) quest for structure-function unity in phonological working memory ("The Search for the Phonological Store: From Loop to Convolution").

The "Fusiform Face Area" is a wonderful example of the merging of structure and function terms -- they are joined in a single moniker: FFA. Could the proposed link be wrong? Indeed it could. The function word "face" is just renting the space between "fusiform" and "area", it can always be cleaved, excised, extracted from that position if the evidence warrants. Until that time, however, more work is needed.