Christof Koch and the Neural Correlates of Consciousness


Scholarpedia has an entire entry on the neural correlates of consciousness, which argues for including the neural correlates for conscious precepts (that’s a dog!) as any part of understanding how we are consciously aware. In this case, the neural correlates of both basal arousal (see image below) and activity in the inferior temporal cortex are necessary for us to be consciously aware.

This Scholarpedia page is maintained by Christof Koch and Florian Mormann, both at Caltech. Mormann is a post-doc; his latest article on “Latency and selectivity of single neurons indicate hierarchical processing in the human medial temporal lobe” (pdf) appeared in the Journal of Neuroscience.

Koch wrote the popular book The Quest for Consciousness: A Neurobiological Approach based on his collaborative work with Francis Crick. Here is Michael Shermer reviewing the book at Scientific American:
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Fall prevention in older people — Stephen Lord at HCSNet

Sway meter, subject on foam
Sway meter, subject on foam
Daniel isn’t the only guy at Neuroanthropology who gets to go to good conferences; last week, while in the throes of a cold brought on by fieldwork with the 15-and-under Sydney city select rugby team, I got to go to the HCSNet Workshop on Speech, Perception and Action held at Western Sydney University.

HCSNet is funded by the Australian Research Council to promote research on human communication. I only got to go to the second day of the two-day conference (because I was cooking meals for 20 hungry rugby hopefuls the first day), but I saw a number of great presentations, including talks by Catherine Best, MARCS Auditory Laboratories, UWS, Beatriz Calvo-Merino, University College London, and Stephen Lord, Prince of Wales Medical Research Institute. I’ll blog soon on Dr. Calvo-Merino, one of the high points of the day, but today I want to make some notes on Prof. Lord’s fascinating research and talk.

Prof. Lord heads the Falls and Balance Research Group. Visit the group’s website for publications and some great information about risk factors for falling. At the conference, Lord discussed the group’s extensive applied research examining different factors that contribute to older people falling and experimental interventions to decrease the contribution of any single factor. The project has created a screening procedure for use by general practitioners to evaluate an older person’s likelihood of falling.

As regular readers know, I’m particularly interested in the way humans maintain equilibrium (see earlier posts, Kids falling down and Equilibrium, modularity, and training the brain-body, and Daniel’s post of some great parkour video, Free Running and Extreme Balance). In the longer of these posts (Equilbrium, modularity…), I specifically discussed how the ‘sense of balance’ is actually a much more complex synthesis of multiple sensory inputs, both exteroception (perception of the world) and interoception (perception of the self).

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Synesthesia & metaphor — I’m not feeling it

Wired online carried a story recently on a talk by ‘neuroscientist extraordinaire’ V.S. Ramachandran, one of the folks responsible for a lot of creative thinking in the brain sciences. Brandom Keim writes on a recent talk Ramachandran gave at the World Science Festival in a story, Poetry Comes from Our Tree-Climbing Ancestors, Neuroscientist Says. While I typically find his stuff both fascinating and resonant, this particular piece left me unpersuaded.

Normally, I might take issue with the sloppy logic of the title (‘poetry’ coming from ‘tree-climbing ancestors’ being a dangerous conflation between non-proximate contributing factors and eventual effects — you could just as logically say that ‘poetry comes from spinning disk of post-stellar material in proto-solar system’…), but I’ve got bigger fish to fry: synesthesia.

Rmachandran’s work on synesthesia is excellent; for example, his piece with in Neuron on synesthesia is essential reading, and the piece he co-authored on the condition in Scholarpedia is my source for a fair bit of what I will write. The problem is that I don’t think that synesthesia is a good metaphor for, well, metaphor.

Although there may be some ways that metaphor is like synesthesia, when we add up the pros and cons, synesthesia as a metaphor for metaphor may not help us too much to understand the latter, and I seriously doubt that the two are linked in a more profound causal fashion (like a ‘gene’ for both synesthesia and metaphor). Similarly, attention-based failure to perceive something may be like blindness, but using one to try to explain the other is futile. In other words, not all metaphors are equally useful, and I’m concerned that the synesthesia metaphor for metaphor might do more harm than good.

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Lessons from sarcasm (so useful…)

The New York Times ran a story on brain imaging studies of sarcasm, The Science of Sarcasm (Not That You Care), by Dan Hurley. That’s right — that favourite rhetorical tool of the snarky adolescent has been subjected to brain imaging studies. The Pearson Assessment video — of an actor delivering the same lines twice, once sincerely, and once dripping sarcasm — is fun. I found myself thinking that I could have been MORE sarcastic.

Hurley, the author of the NYTimes article, does a pretty good job of explaining things, although I think that the idea that perceiving sarcasm requires a ‘theory of mind,’ alluded to in the article, is a bit of a problem — but I have that issue with a lot of the ‘theory of mind’ material because I think it ‘over-cognizes’ social perception (that’s my own issue, so I won’t dwell on it). Hurley discusses the research of Katherine P. Rankin, using MRI scans and the Awareness of Social Inference Test, or Tasit. I have looked on the website for the Memory and Aging Center of UCSF, and through PubMed and EurekAlert, but I can’t find the original report on this research (please post a comment if you know where it is).

“I was testing people’s ability to detect sarcasm based entirely on paralinguistic cues, the manner of expression,” Dr. Rankin said. What seems particularly interesting is that the part of the brain which seemed to be linked to sarcasm — damage to it by dementia impeded the ability to recognize sarcasm — was in the right hemisphere, not usually associated with language or social interaction (which are generally associated with the left hemisphere). Instead, sarcasm seemed to require activity in ‘a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests.’

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Children integrating their senses

Blogging on Peer-Reviewed ResearchTwo of the pieces that I have wanted to discuss appear together in Current Biology, both on evidence of sensory integration in adults compared to their integration in children. Nature News carried a story about both articles, One sense at a time, by Matt Kaplan. As Kaplan explains, the research generally supports the idea that: ‘Adults readily integrate sight, sound, smell, taste and touch in their everyday lives without a second thought. But research is revealing that this is not the case with children. Two new studies hint that children under the age of eight only use one sense at a time to judge the world around them.

As I started to discuss in an earlier piece on human equilibrium (long ago — still working on parts two and three), adults learn how to weight different sensory information depending on context and the task at hand, evaluating one stream against another if they conflict. When confronted with two contradictory impressions from different senses — such as video of a person saying one thing and audio of a slightly different word — adult sensory systems figure out a way to integrate the sense world, sometimes creating ‘sensory’ compromises or syntheses. The ability to integrate sensory information is fundamental to normal human functioning, but it tends to undermine certain conceptions of brain ‘modularity,’ as I argued in the earlier post.

But with these two articles, I want to explore something a bit different, so I’m going to tackle each one individually, and then reflect on one issue that I think is important: the tendency to see child development in a teleological framework, that is, as an incomplete version of an adult system rather than as a deployment of the child’s distinctive neural resources. Before you click on ‘read more’ below though, be warned; this piece is a bit long…

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Perception and Politics

Do we really know what’s going on? Or do we just see what we want to see?

The Data

Larry Bartels, director of the Center for the Study of Democratic Politics at Princeton, has an op-ed Who’s Bitter Now? which shows us a stereotype of rural voters in action. His argument? “Small-town people of modest means and limited education are not fixated on cultural issues. Rather, it is affluent, college-educated people living in cities and suburbs who are most exercised by guns and religion. In contemporary American politics, social issues are the opiate of the elites.”

Bartels sets out to actually define the “small-town working class,” making less than $60,000, living in small towns or rural areas, never graduated from college. He compares them to cosmopolitan voters, college graduates who live in the suburbs or cities making $60,000 or more. The first group makes up about 16 percent of voters, the second 13 percent.

Small-town, working-class people are more likely than their cosmopolitan counterparts, not less, to say they trust the government to do what’s right. In the 2004 National Election Study conducted by the University of Michigan, 54 percent of these people said that the government in Washington can be trusted to do what is right most of the time or just about always. Only 38 percent of cosmopolitan people expressed a similar level of trust in the federal government.

Do small-town, working-class voters cast ballots on the basis of social issues? Yes, but less than other voters do. Among these voters, those who are anti-abortion were only 6 percentage points more likely than those who favor abortion rights to vote for President Bush in 2004. The corresponding difference for the rest of the electorate was 27 points, and for cosmopolitan voters it was a remarkable 58 points. Similarly, the votes cast by the cosmopolitan crowd in 2004 were much more likely to reflect voters’ positions on gun control and gay marriage.

Bartels finishes by telling us the larger pattern behind it all. “It is true that American voters attach significantly more weight to social issues than they did 20 years ago. It is also true that church attendance has become a stronger predictor of voting behavior. But both of those changes are concentrated primarily among people who are affluent and well educated, not among the working class.”

The Interpretation

So why the problem in perception? Is it because he clings to a stereotype, as Bartels seems to suggest?

Nicholas Kristof’s column today, Divided They Fall, offers us better than a yes/no. He wants to take on “how our biases shape our understanding of reality.” Of course the candidate you favor won the debate last time… Or did he or she?

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