Thursday, February 23, 2006

I Wanna Hold Your Hand

This one was widely covered in the popular press a few weeks ago, albeit the Psychological Science article itself has yet to appear in print (or in cyberspace). From the New York Times:

Holding Loved One's Hand Can Calm Jittery Neurons

Married women under extreme stress who reach out and hold their husbands' hands feel immediate relief, neuroscientists have found in what they say is the first study of how human touch affects the neural response to threatening situations.

The soothing effect of the touch could be seen in scans of areas deep in the brain that are involved in registering emotional and physical alarm.

The women received significantly more relief from their husbands' touch than from a stranger's, and those in particularly close marriages were most deeply comforted by their husbands' hands, the study found.

In the first sentence, the words "extreme stress" jumped out at me. What could be the source of this extreme stress? Being threatened by a barking Doberman? Enduring a tough round of questioning by your dissertation committee? Getting a phone call from your boss, who explains why you've been passed over for a promotion, while the twins are screaming in the background? Jumping out of an airplane? Undergoing a tumor biopsy? OK, OK, this is an fMRI experiment, so the source of the "extreme stress" was:

"knowing that they would periodically receive a mild electric shock to an ankle..."

Oh, I see.
Brain images showed peaks of activation in regions involved in anticipating pain, heightening physical arousal and regulating negative emotions, among other systems.

But the moment that they felt their husbands' hands — the men reached into the imaging machine — each woman's activity level plunged in all the regions gearing up for the threat. A stranger's hand also provided some comfort, though less so.

All right, now none of this coverage is the fault of the researchers who conducted the study (which was not available to The Neurocritic for review).

What I really wanted to comment on is the personal observation that when under an actual state of extreme stress (say, in a hospital after major surgery when your temperature is 38.5° C, your limbs are tingling, you're extremely light-headed and dizzy, with deficient hematocrit, "tunnel hearing," and low blood pressure despite an excessive amount of pain and anxiety, just to name an example), being touched by anyone (e.g., a nurse) can be very comforting.

Other questions raised by this study: what about married women holding their mothers' hands? married men holding their wives' hands? unmarried women holding their partners' hands? single women holding the hands of their best friends? Perhaps the authors started with the relationship that they most expected to yield significant results...

ADDENDUM: The paper is available here, after all.

James A. Coan, Hillary S. Schaefer, and Richard J. Davidson

Social contact promotes enhanced health and well being, likely as a function of the social regulation of emotional responding in the face of various life stressors. For this functional magnetic resonance imaging (fMRI) study, 16 married women were subjected to the threat of electric shock while either holding their husband’s hand, holding the hands of anonymous male experimenters, or holding no hand at all. Results indicated a pervasive attenuation of activation in the neural systems supporting emotional and behavioral threat responses as a function of spousal handholding. A more limited attenuation of activation in these systems occurred as a function of stranger handholding. Most strikingly, the effects of spousal handholding on neural threat responses varied as a function of marital quality, with higher marital quality predicting less threat-related neural activation in the right anterior insula, superior frontal gyrus and hypothalamus during spousal, but not stranger, handholding.

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Tuesday, February 21, 2006

Neuromarketing and "the Super Bowl Brain Scans"

This one's from Vaughan at Mind Hacks, who does a superb job of debunking this ridiculous exercise in publicity and hype. His post is reprinted below. No additional comments from The Neurocritic are needed.

The 'complete results' from the Super Bowl brain scans are online, and it does indeed seem as if the exercise has been mostly hype.

Cardinal sins:

1) Not giving the comparison conditions and experimental design. This makes the reported results essentially meaningless.

2) Interpreting brain activity in certain areas to mean a certain response from viewers, even when they actually report something else.

female subjects may give verbally very low 'grades' to ads using actresses in sexy roles, but their mirror neuron areas seem to fire up quite a bit, suggesting some form of identification and empathy.

Mirror neurons tend to fire when anyone else's actions are viewed, there is no evidence that approval or liking of the person doing the actions has any bearing on the response.

3) Assuming activation in the 'mirror system' equals empathy.

4) Assuming activation of the amygdala is a measure of fear.

There is a big jump in amygdala activity when the dinosaur crushes the caveman... The scene looks funny and has been described as funny by lots of people, but your amygdala still perceives it as threatening

The amygdala can be active when someone experiences happiness or joy. Equally, it could have been active because people found the scene funny.

5) Finishing on an advert for the neuromarketing company involved.

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Monday, February 20, 2006

Back from Detox!

The Neurocritic is back from a two week stint in a rapid detox program at an undisclosed European location. Semi-regular posting will commence shortly.

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Saturday, February 04, 2006

More Lies... Damn Lies...

Well, there's a lengthy new article on neuro-lie detection in the New York Times Magazine, which quotes the aforementioned Dr. Langleben (among others):

Looking for the Lie

Liars always look to the left, several friends say; liars always cover their mouths, says a man sitting next to me on a plane. Beliefs about how lying looks are plentiful and often contradictory: depending on whom you choose to believe, liars can be detected because they fidget a lot, hold very still, cross their legs, cross their arms, look up, look down, make eye contact or fail to make eye contact. Freud thought anyone could spot deception by paying close enough attention, since the liar, he wrote, "chatters with his finger-tips; betrayal oozes out of him at every pore." Nietzsche wrote that "the mouth may lie, but the face it makes nonetheless tells the truth."

Still quite the timely topic, so The Neurocritic feels obligated to weigh in here. This quote jumped out after a cursory glance:

Langleben performed his card experiment again in 2003, with a few refinements, including giving his subjects the choice of two cards to lie about and whether to lie at all. This second study found activation in some of the same regions as the first, establishing a pattern of deception-related activity in particular parts of the cortex: one in the front, two on the sides and two in the back. The finding in the back, the parietal cortex, intrigued Langleben.

"At first I thought the parietal finding was a fluke," he said. The parietal cortex is usually activated during arousal of various kinds. It is also involved in the manifestation of thoughts as physical changes, like goose bumps that erupt when you're afraid, or sweating that increases when you lie. The connection to sweating interested Langleben, since sweating is also one of the polygraph's hallmark measurements. He looked at existing studies of this response, and in all of them he found activity that could be traced back to the parietal lobe. Until Langleben's observation of its connection to brain changes, the sweat response (which the polygraph measures with sensors on the palm or fingertips) had been thought to be a purely "downstream" change, a secondary effect caused not by the lie itself but by the consequences of lying: guilt, anxiety, fear or the excess positive emotion one researcher calls "duping delight." But Langleben's findings indicated that it might have a corollary "upstream," in the central nervous system. This meant that at least one polygraph measurement might have a signature right at the source of the lie, the brain itself.

Yeah, right, like the parietal cortex is the "seat of arousal." This is one of the most annoying problems about neuroimaging... researchers will say, after all the results are analyzed, "well of course we thought the parietal lobe would be associated with sweating and other autonomic measures!" when, in fact, that is not what they expected at all. But maybe he means association areas in the anterior parietal cortex?

On the other hand, increased activity in the anterior cingulate cortex (ACC) has been associated with arousal and autonomic activation, according to the work of Tomas Paus, Hugo Critchley, and others. It would be logical that the ACC would respond when a person is lying, and one need not postulate that it's for cognitive reasons (e.g., choosing between conflicting responses, as mentioned below):

Brain mappers are just beginning to figure out how different parts of the brain function. The function of one region found to be activated in the five-of-clubs experiment, the anterior cingulate cortex, is still the subject of some debate; it is thought, among other things, to help a person choose between two conflicting responses, which makes it a logical place to look for a signature of deception. This region is also activated during the Stroop task, in which a series of words are written in different colors and the subject must respond with what color the ink is, disregarding the word itself. This is harder than it sounds, at least when the written word is a color word that is different from the ink it is written in. If the word "red" is written in blue, for instance, a lot of people say "red" instead of "blue." Telling a spontaneous lie is similar to the Stroop task in that it involves holding two things in mind simultaneously — in this case, the truth and the lie — and making a choice about which one to apply.

In fact, here's a study that observed a correlation between mean arterial pressure during the Stroop task and greater BOLD activation in the ACC, among other regions (insula, thalamus, periaqueductal gray):

Gianaros PJ, Derbyshire SW, May JC, Siegle GJ, Gamalo MA, Jennings JR.
Anterior cingulate activity correlates with blood pressure during stress.
Psychophysiology. 2005 Nov;42(6):627-35.

Gianaros et al. concluded that their results "support the hypothesis that the anterior cingulate cortex regulates blood pressure reactions to behavioral stressors in humans."

SO is fMRI an improvement over the polygraph, you ask? Stay tuned...

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Friday, February 03, 2006

The "Face Module" Identified in Moneys?

Oooh... aah... besides the general concept of such a specialized module, it's hard for The Neurocritic to find fault with this one:

A Cortical Region Consisting Entirely of Face-Selective Cells
Doris Y. Tsao, Winrich A. Freiwald, Roger B. H. Tootell, Margaret S. Livingstone
Science 3 February 2006: Vol. 311. no. 5761, pp. 670-674

Face perception is a skill crucial to primates. In both humans and macaque monkeys, functional magnetic resonance imaging (fMRI) reveals a system of cortical regions that show increased blood flow when the subject views images of faces, compared with images of objects. However, the stimulus selectivity of single neurons within these fMRI-identified regions has not been studied. We used fMRI to identify and target the largest face-selective region in two macaques for single-unit recording. Almost all (97%) of the visually responsive neurons in this region were strongly face selective, indicating that a dedicated cortical area exists to support face processing in the macaque.

Using fMRI, the authors identified a face-specific area homologous to the human fusiform face area (FFA) in two macaque monkeys. Then they recorded from single neurons in this ~16mm2 region along the superior temporal sulcus.

[NOTE: of course, face-selective cells were identified in primate temporal cortex by Rolls, Gross, Perrett, etc. well before the advent of fMRI and discovery of the human FFA... but I digress.]

They tested the face selectivity of 405 neurons by presenting pictures of items from different categories (faces, bodies, fruits, gadgets, hands, and scrambled patterns). About 80% of the neurons were classified as visually responsive. In 97% of the neurons (i.e., all but 8 out of the 310 visually responsive cells), responses to faces were at least 2 times greater than responses to pictures from other categories.

SUMMARY from The Neurocritic: Now all they have to do is to lesion this face-selective region and then see what happens to the monkeys' face recognition abilities. Are there enough other "face selective" neurons distributed elsewhere in the temporal lobe to support face recognition?

ADDENDUM and Disclaimer: The Neurocritic is not necessarily endorsing animal research by posing that rhetorical question.

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Thursday, February 02, 2006

Would I Lie to You?

An engaging series of articles on the ethics of neuro-deception-detection appeared in the American Journal of Bioethics last year. The lead article, by Wolpe et al., argued that,

"Premature commercialization will bias and stifle the extensive basic research that still remains to be done, damage the long-term applied potential of these powerful techniques, and lead to their misuse before they are ready to serve the needs of society."
--Wolpe et al. (2005), p. 47

Wolpe PR, Foster KR, Langleben DD.
Emerging neurotechnologies for lie-detection: promises and perils.
Am J Bioeth. 2005 Spring;5(2):39-49.

These authors went on to chastise those who are trying to profit from this venture before the methods are scientifically proven. Particularly taken to task was Lawrence Farwell and his patented "brain fingerprinting" technology, which uses EEG recordings instead of fMRI. The technique is based on the "oddball" P300, an ERP component that is elicited by "guilty knowledge" probe stimuli scattered among irrelevant items. Farwell and Donchin first presented the results at the 1986 meeting of the Society for Psychophysiological Research and later published a paper in 1991. Dr. Emanuel Donchin, P300 guru, states that the science behind the method is not the problem.

Instead, the specific questions posed to the suspect are problematic. [Donchin] argues that "the success of the technique depends on the construction of the stimuli and there is no analytic, systematic way of constructing the question. It depends on the subjectivity of the person. It’s an art, not a science."

taken from
Brain Fingerprinting: Picture-perfect crimes
By Tami Abdollah

Farwell's Brain Fingerprinting Laboratories, Inc. makes rather exaggerated claims for applications in counterterrorism, criminal justice, medicine, advertising, etc.

J. Peter Rosenfeld, Ph.D.
was actually the first to publish a journal article on lie dection and P300. He and his colleagues did a recent study on how to beat the P300 guilty knowledge test. The countermeasures are similar to those described for beating a polygraph test: ask the subjects to generate large covert responses to irrelevant stimuli (or to the "control" questions on a polygraph).

NOW back to the ethics article by Wolpe, Foster, & Langleben on the perils of premature adoption. Imagine The Neurocritic's surprise with the discovery that Dr. Langleben is on the Science Board for a company called No Lie MRI, Inc., and that he holds a patent for the lie detection fMRI technology!

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