Neuroeconomics

Internships for Neuroeconomists?

A google search inspired by this article in Science Careers on non-academic careers for behavioral scientists led me to this link about internships at Fidelity Investments's "Center for Applied Behavioral Economics"(no link)...

"Candidates pursuing doctoral or post-doctoral studies in decision theory, cognitive psychology, and/or economics are encouraged to apply."

The posting was at the end of March, but you never know, there may still be an opportunity for a budding neuroeconomists to break out that suit and tie that's been collecting dust for so long.

As a side note, a note on Brian Knutson's recent Neuron paper (along with his smiling mug) is mentioned in the adjacent article on neuromarketing.

Neural synchronization: what information is fMRI missing?

A new single-cell firing study from MIT observes prefrontal activation to assign salience to novel stimuli, and parietal activity to draw attention to stimuli already recognized as salient. What I'm more excited about, is their discussion of neural synchrony as a conduit of information.

This review article from last fall provides a nice overview, and I've been seeing it crop up more and more. Unfortunately fMRI is too slow to capture this information; the review discusses EEG studies in humans. Perhaps it is time to start thinking about this signal domain and its application to neuroeconomics.

Ambiguity and Pessimism Bias

Although Saturday Night Live may be in the midst of a prolonged rough stretch, Debbie Downer is one of my all-time favorite characters (see a video or the Wikipedia entry). For those who are unfamiliar, the central figure in these sketches is a miserable cynic who constantly rains pessimism on others’ parades. A recent study, published in NeuroImage, examines if this type of behavior has neural underpinnings:

Based on the assumption that information processing is biased towards potentially negative events in order to prepare response strategies efficiently for coping with unfavorable consequences, we hypothesized that emotion processing brain areas are activated during ‘unknown’ expectation which are also activated during expectation of negative events.

 Here is the authors’ main result:

Taken together, we found evidence for a ‘medial-thalmic-insular-inferior-frontal-rubral’ circuit associated with expecting events of unknown emotional valence, the activity of which resembled the expectation of negative events and also correlated with individual depressiveness. The revealed areas are consistent with the proposed ‘ventral system’ of emotion processing for identification of the emotional significance of a stimulus, production of affective state, and autonomic response regulation…Our results are consistent with the view of brain activity reflecting a ‘pessimistic’ or ‘cautious’ bias toward future events.

Apparently, we’re all wired to be downers in a world characterized by pervasive ambiguity. Somewhere in the course of human evolution, though, people’s views toward their pessimistic peers have changed – whereas downers of the distant past likely served to possess and distribute valuable information, they’re a drag in 21^st-century America. What used to be an advantageous survival strategy is now, at least in well-off societies, a social nuisance and an object of mockery. Is this transformation not a testament to how well off we have become? 

Neuroscience and Culture

The initial edition (June, 2006) of Social Cognitive and Affective Neuroscience included a paper by Heatherton, Wyland, Macrae, Demos, Denny and Kelley that uses fMRI to differentiate the neural representation of oneself from that of one’s best friend: 

Whereas neural responses to self-judgments in the …MPFC ROI…approximated a baseline level of MPFC activity, neural responses to intimate other- and non-referential-judgments were significantly deactivated relative to baseline.

Therefore, 

The present results indicate an MPFC response that is self-specific – namely judgments pertaining to oneself were seen to be distinct from those made for one’s friend.

In the February 1, 2007 edition of Neuroimage, Zhu, Zhang, Fan and Han question whether the self-other neural differentiation is culture-specific: 

Social psychologists have found that Westerners (North Americans and Europeans) tend to view the self as an autonomous entity separating from others and to behave according to their own internal attributes and thoughts (the independent self). In contrast, East Asians emphasize the interconnectedness of human beings along with contingencies between the individual’s behavior and the thoughts and actions of others in the relationship (the interdependent self). However, it remains unknown how the cultural influence on self-representation is accomplished in the human brain.

Whereas the Heatherton experiment recruited subjects solely from the Dartmouth area (justifiably with no mention of nationality), Zhu et al scanned both Western (6 English, 4 American, 2 Australian and 1 Canadian who all were living in China for less than a year) and East Asian subjects in their laboratory in China. Here are their results: 

In Chinese individuals, mother-judgments generated enhanced MPFC activity compared with other-judgments and the null condition. Consequently, the representation of Chinese mother cannot be distinguished from the representation of their selves, in terms of the MPFC activity, indicating that Chinese individuals use MPFC to represent both mother and the self. In contrast, MPFC activity corresponds to a representation of only the individual self in Western subjects.

And here’s the associated implication:

These fMRI results showed strong empirical evidence that MPFC mediates cultural influence on the neural substrates of representation of self and close others. While social psychological studies suggest that cultures create habitual ways of processing information related to the self and one’s important others, our fMRI results indicate that these habitual cognitive processes are accompanied by detectible parallel neural processes. The relatively heavy emphasis on interpersonal connectedness in Chinese culture has led to the development of neural unification of the self and intimate persons such as mother, whereas the relative dominance of an independent self in Western cultures results in neural separation between the self and others (emphasis mine).

In terms of the mainstream “catch-all” view that culture is “the sum total of ways of living built up by a group of human beings and transmitted from one generation to another,” these results certainly speak for themselves: something about being born and raised within an Eastern Asian community causes an individual’s neural representation of himself to parallel the neural representation of an intimate other.  

But when one takes a multidimensional view of culture, the results of this study open more doors than they close: the “something” that generates “relatively heavy emphasis on interpersonal connectedness in Chinese culture” and the “other thing” that generates a “dominance of an independent self in Western cultures” remain obscured whenever we let the assertion that “culture matters” end the debate.  Given that it undoubtedly matters, what does culture actually mean? 

Consider the issue of scope. To what extent do individual components within the East Asian environment (i.e. family, teachers & peers) separately contribute to the development of the interdependent self? Alternatively, to what extent is the phenomenon driven by the gestalt of East Asian life? Alterations of the Zhu et al study could address these questions. If the experiment was replicated with second-generation Asian Americans, maybe the family-effect could be isolated from the societal-effect. Likewise, the school-effect could be examined by scanning Western subjects who attended Asian schools all throughout childhood. Would the results show that culture is represented by a continuous spectrum – anchored by independence and interdependence at the poles – on which Asian Americans and Americans in Asia can be placed somewhere in the middle? Or does some type of tipping-point phenomenon cause one culture to win out over the other, placing the imaging data toward one of the poles? 

Experiments could certainly shed light on whether the culture-as-a-catchall view needs to be replaced. As knowledge, imaging technology and experimental techniques evolve, perhaps (1) the specific inputs to various cultures can be formally defined and (2) the neural processes that underlie these separate inputs can be illuminated. An understanding of how cultural elements affect brain activity might go a long way in explaining why given institutions succeed in one culture while they fail in others.

Beta blockers also block memories

Yahoo has clips from a recent 60 minutes special posted online on using propanolol to 'weaken' the memories associated with highly stressful events. Propanolol is a beta blocker, and epinephrine is a beta agonist. All sorts of beta receptors in the amygdala, which is the next door neighbors with the hippocampus; presently thought of as the seat of memory.

If you're teaching a psychopharmacology class, here's another chance to show a movie in class. Another popular take on the article is here, and the published article in Biological Psychology is here.

For the love of God...

The August edition of Neuroscience Letters included work by Mario Beauregard and Vincent Paquette that examined whether a “God Spot” could be found in the brain.  Not surprisingly, the paper generated quite a buzz (see here, here and here for various accounts). From the text:

The main goal of this functional magnetic resonance imaging study was to identify the neural correlates of a mystical experience (as understood in a Christian sense) in a group of Carmelite nuns. 

Here are the details of their design:

BOLD signal changes were measured during a Mystical condition, a Control condition, and a Baseline condition. In the Mystical condition, subjects were asked to remember and relive (eyes closed) the most intense mystical experience ever felt in their lives as a member of the Carmelite Order…In the Control condition, subjects were instructed to remember and relive (eyes closed) the most intense state of union with another human ever felt in their lives while being affiliated with the Carmelite order.

Here are the summarized results:

[The Mystical condition] was associated with significant loci of activation in the right medial orbitofrontal cortex, right middle temporal cortex, right inferior and superior parietal lobules, right caudate, left medial prefrontal cortex, left anterior cingulate cortex, left inferior parietal lobule, left insula, left caudate, and left brainstem. Other loci of activation were seen in the extra-striate visual cortex.

So although the study does not support the existence of a “God spot,” it does provide evidence that humans may be wired with a “God network.”

The recent issue of Psychiatry Research: Neuroimaging includes a paper that takes a different approach to the same question. In this experiment, SPECT was used instead of fMRI. Also, the subjects weren’t nuns asked to imagine an experience; they were self-proclaimed Christian women who practice glossolalia. For those who aren’t familiar with glossolalia, check out this movie. Or just read the paper’s abstract:

Glossolalia (or “speaking in tongues”) is an unusual mental state that has great personal and religious meaning. Glossolalia is experienced as a normal and expected behavior in religious prayer groups in which the individual appears to be speaking in an incomprehensible language. This is the first functional neuroimaging study to demonstrate changes in cerebral activity during glossolalia. The frontal lobes, parietal lobes, and left caudate were most affected.

A subscription is required to view the full text of the article, but here is a summary. Also, see the Neurocritic for deeper perspective and other informative links. Like the previous paper, this one also suggests that evidence points to a “God network,” but not a “God spot.”

But should such a definitive conclusion really be drawn? Consider the following fundamental rule of experimentation: to measure a variable’s effect across treatments, everything except this variable must be held constant. If a design’s treatments differ in multiple ways, a given change cannot be attributed to a particular variable of interest. Thus, in order for these studies to isolate the effect of a religious experience, other effects must be controlled for.

The researchers who scanned the nuns anticipated this issue. Following the image acquisition, an item on a self-report questionnaire asked the nuns to rate the level of intensity that they felt when imagining the religious and non-religious experiences in the scanner. Because there was no significant difference between religious ratings and non-religious ratings, one can plausibly conclude that the “intensity effect” was controlled for.

But other variables besides intensity may be at work. Consider that the nuns in the control phase were simply asked to imagine an intense interaction with “another human.” Given this feature of the design, the results imply that the imaging data associated with an imagined interaction with God is different that the data associated with an imagined interaction with anther human. But what if the other human was instead one’s child or significant other? (Don’t let the fact that nuns aren’t likely to have children or significant others interfere with the thought experiment.) The results cannot shed any light on whether the neural response generated when someone thinks about God is significantly different than the response generated when someone thinks about an individual near and dear to her heart.

In a similar vein, consider that the control phase in the glossolalia experiment involved women singing along with a recorded religious song. Therefore, the design allows one to conclude that the response to glossolalia is different than the response to singing a religious song that someone else created. As another thought experiment, consider the extent to which the results might be different if the control phase involved someone singing her own song. Perhaps a song-writer’s sense of ownership and/or profound attachment to the words that she sings generates a neural response that does not significantly differ from that which is observed during glossolalia.

In truth, child-rearing nuns (with or without husbands) and song-writing glossolalia practitioners hardly form effective sample sizes. But the theoretical examples highlight an important practical issue: before anyone can use experiments to demonstrate that there is “something about God,” innovative techniques must bridge the gap between the spiritual and the mundane. Until they do, there is simply no way to know whether the brain’s response to a religious experience is quantitatively different than its response to any of the deeply meaningful stimuli that surround our daily lives.

 

 

Ketamine and Depression, part 2

Following up on our earlier post on Ketamine and depression, Nature has a news feature providing more background on the topic.

Journal Watch

Nature's website includes two neuroecon news features.  One describes this paper in forthcoming Science; the other is a general state-of-the-discipline piece.

Genetic Expression may Determine Handedness

There is a nice review in Nature Reviews Neuroscience on the mechanism that causes asymmetry in the brain. One of the theories discussed is that molecules produced in the embryonic brain that induce cell specialization are distributed asymmetrically in the hemispheres, which starts a chain reaction leading to hemispheric specialization. Competing theories have suggested fetal position, or development that occurs postpartum.

Handedness is interesting to neuroeconomists and others because imaging studies frequently exclude left-handed individuals because activation patterns in left-handed individuals are inconsistent even among lefties, and don't correlate well with data obtained from right-handed individuals.

Almost of equal interest in this review is the fact that hemispheric specialization may be influenced by the "Sonic Hedgehog" gene. I'm glad that (a) I have a Sonic Hedgehog gene and (b) such a gene exists in the first place.

Lesions and the Valuation of Information

Information economics is based on the premise that information is a scarce commodity. Because its acquisition is costly, the economic actor weighs the value of an additional unit of information against his/her highest valued alternative. In this sense, information is no different than any tangible good that can be bought and sold. The September issue of Science includes a paper by Rudebeck, Buckley, Walton and Rushworth that integrates neuroecon and info-econ via a lesion study on macaques:

We assessed how selective lesions of ACC gyrus (ACC_G), ACC sulcus (ACC_S), or lateral orbital and ventral prefrontal cortex (PFv+o) affect the way macaques value social information.

And how were the monkeys’ valuations measured?

Measurements were made of latencies to pick up food items in the presence of fear-inducing stimuli (toy snakes) in experiment 1, social stimuli (short films of other macaques) in experiment 2, or neutral control objects. The latencies indexed the macaques’ assessment of the value of obtaining further information about the stimulus before reaching and reflected their relative valuation of the stimulus in contrast to the incentive of the food.

When confronted with the fear-inducing information,

[Control animals with no lesion] were consistently reluctant to take food from above a moving toy snake, but the case was significantly different for both the PFv+o group and the ACC_S group…There were no significant differences between the ACC_G and controls.

The behavior of the ACC_G group, however, was significantly different from the other three groups when social information was presented:

[Controls] were slower to pick up food in the presence of a large staring male, a female macaque with visible sexual perineal swellings, and a midsized macaque making affiliative lip-smacking gestures…The ACC_G group remained uninterested in any of the images of other macaques…By contrast, comparable modulations of reaching latencies were seen in PFv+o and ACC_S groups as in the controls, and there were no significant differences between any of these three groups. 

The results enable the researchers to draw the following conclusions:

The ACC region critical for mediating the valuation of social stimuli appears to be the ACC_G immediately rostral and dorsal to the genu of the corpus callosum and includes areas 32 and rostral area 24. 

Complete ACC_S lesions only affected the mild fear task significantly and not the social task. 

(Note that Brodmann’s area 32 refers to the dorsal ACC, while BA 24 refers to the ventral ACC. The experiment described here suggests that the lesions to the dorsal ACC and the ventral ACC may have differential effects that sum to produce the observed social deviancy.)

If the latency measure legitimately represents the monkeys’ opportunity cost of acquiring more information, these results suggest the following economic interpretation: (1) An ACC_G lesion decreases monkeys’ willingness to pay for social information; (2) Lesions of the ACC_S and lateral orbital and ventral prefrontal cortex increase monkeys’ willingness to pay for information relating to fearful stimuli.