Blog reader Patrice responded to the previous posting in a comment asking about the possibly of my doing podcasts on some mindblog topics. Another friend has mentioned this, yet I haven't thought much about it because I've never really gotten into listening to podcasts myself. When I am driving I usually listen to music. However, I am an experienced university lecturer, and actually sort of miss the more spontaneous and improvisational energy of talking versus writing. So, I'm curious to know how many of you might actually find occasional podcasts useful. And if so, do you have opinions about optimal length and subjects that are most interesting to you? I would appreciate responses, either to this posting, or by email to firstname.lastname@example.org.
Friday, October 31, 2008
Although I feel totally immodest about doing this, I have to pass on this text of a email today from a reader of this blog in Tasmania, Australia. Whenever I question how worthwhile this effort is, a statement like this really warms me up:
Just a quick appreciation: I love your blog. I don’t know how you do it but just about every day there’s something that I really want to read. You appear to write a blog that is bang on some of my interests, in particular, building the full - crazy, intelligent, imaginative, smart, musical, superstitious, religious, even - human from biology. We appear to be living in a very exciting time where a lot of stuff that was in what I’d call the realm of superstition – is being dusted off and actually inspected. Maybe it’ll go on like this forever, but I can’t imagine that we won’t run out of things pretty soon at the current rate.
I point to two interesting articles in the New York Times. Dewan and Brown discuss how the work of psychologist Drew Westen (mentioned in three - previous - posts) has shaped the message delivery of democratic candidates so thoroughly that the rhetorical dominance enjoyed by republican for years has been completely reversed. Kristof deals again with the issue of unconscious bias in voters, and links in his article direct you to online tests for your own unconscious biases.
Just as ants interact to form elaborate colonies and neurons interact to create structured thought, groups of people interact to create emergent organizations that the individuals may not understand or even perceive. I recently went to an interesting seminar on this topic in the Psychology Department at Univ. Wisc. given by Robert Goldstone at Indiana Univ. He has set up an interesting web based experiment to test agent based models of emergent properties of human groups. You can read about and also become a subject in the experiments here.
Thursday, October 30, 2008
I pass on clips from an article by Pascal Boyer that explains why a slew of cognitive traits shared by humans will always make atheism a hard sell.
In the past ten years, the evolutionary and cognitive study of religion has begun to mature. It does not try to identify the gene or genes for religious thinking. Nor does it simply dream up evolutionary scenarios that might have led to religion as we know it. It does much better than that. It puts forward new hypotheses and testable predictions. It asks what in the human make-up renders religion possible and successful. Religious thought and behaviour can be considered part of the natural human capacities, such as music, political systems, family relations or ethnic coalitions. Findings from cognitive psychology, neuroscience, cultural anthropology and archaeology promise to change our view of religion.
Unlike other social animals, humans are very good at establishing and maintaining relations with agents beyond their physical presence; social hierarchies and coalitions, for instance, include temporarily absent members. This goes even further. From childhood, humans form enduring, stable and important social relationships with fictional characters, imaginary friends, deceased relatives, unseen heroes and fantasized mates. Indeed, the extraordinary social skills of humans, compared with other primates, may be honed by constant practice with imagined or absent partners.
It is a small step from having this capacity to bond with non-physical agents to conceptualizing spirits, dead ancestors and gods, who are neither visible nor tangible, yet are socially involved. This may explain why, in most cultures, at least some of the superhuman agents that people believe in have moral concerns.
In addition, the neurophysiology of compulsive behaviour in humans and other animals is beginning to shed light on religious rituals. These behaviours include stereotyped, highly repetitive actions that participants feel they must do, even though most have no clear, observable results, such as striking the chest three times while repeating a set formula. Ritualized behaviour is also seen in patients with obsessive-compulsive disorders and in the routines of young children. In these contexts, rituals are generally associated with thoughts about pollution and purification, danger and protection, the required use of particular colours or numbers or the need to construct a safe and ordered environment.
So is religion an adaptation or a by-product of our evolution? Perhaps one day we will find compelling evidence that a capacity for religious thoughts, rather than 'religion' in the modern form of socio-political institutions, contributed to fitness in ancestral times. For the time being, the data support a more modest conclusion: religious thoughts seem to be an emergent property of our standard cognitive capacities.
Religious concepts and activities hijack our cognitive resources, as do music, visual art, cuisine, politics, economic institutions and fashion. This hijacking occurs simply because religion provides some form of what psychologists would call super stimuli. Just as visual art is more symmetrical and its colours more saturated than what is generally found in nature, religious agents are highly simplified versions of absent human agents, and religious rituals are highly stylized versions of precautionary procedures. Hijacking also occurs because religions facilitate the expression of certain behaviours. This is the case for commitment to a group, which is made all the more credible when it is phrased as the acceptance of bizarre or non-obvious beliefs.
Some form of religious thinking seems to be the path of least resistance for our cognitive systems. By contrast, disbelief is generally the result of deliberate, effortful work against our natural cognitive dispositions — hardly the easiest ideology to propagate.
One hears charges from both left and right about media bias, with FOX News frequently cited as the most extreme case. Tim Groeling has done interesting work to objectively measure the bias shown by television media, in a paper (PDF here) to be published in the December issue of Presidential Studies Quarterly. He simply collected the in-house presidential approval polling by ABC, CBS, NBC and FOX News and compared these with the actual broadcasts of such polls on evening news shows from 1997 to early 2008. As an example, CBS was 35 percent less likely to report a five-point drop in approval for Bill Clinton than a similar rise in approval and was 33 percent more likely to report a five-point drop than a rise for George W. Bush. FOX News was 67 percent less likely to report a rise in approval for Clinton than a decrease and 36 percent more likely to report an increase rather than a decrease for Bush.
Wednesday, October 29, 2008
An interesting piece in Jour. of Neuoscience by Belova et al., in which recordings from single cells in the monkey amygdala indicate their division into those that track either positive state or negative states:
As an organism interacts with the world, how good or bad things are at the moment, the value of the current state of the organism, is an important parameter that is likely to be encoded in the brain. As the environment changes and new stimuli appear, estimates of state value must be updated to support appropriate responses and learning. Indeed, many models of reinforcement learning posit representations of state value. We examined how the brain mediates this process by recording amygdala neural activity while monkeys performed a trace-conditioning task requiring fixation. The presentation of different stimuli induced state transitions; these stimuli included unconditioned stimuli (USs) (liquid rewards and aversive air puffs), newly learned reinforcement-predictive visual stimuli [conditioned stimuli (CSs)], and familiar stimuli long associated with reinforcement [fixation point (FP)]. The FP had a positive value to monkeys, because they chose to foveate it to initiate trials. Different populations of amygdala neurons tracked the positive or negative value of the current state, regardless of whether state transitions were caused by the FP, CSs, or USs. Positive value-coding neurons increased their firing during the fixation interval and fired more strongly after rewarded CSs and rewards than after punished CSs and air puffs. Negative value-coding neurons did the opposite, decreasing their firing during the fixation interval and firing more strongly after punished CSs and air puffs than after rewarded CSs and rewards. This representation of state value could underlie how the amygdala helps coordinate cognitive, emotional, and behavioral responses depending on the value of one's state.
The random samples section of Science Magazine discusses the latest prosperity or 'happiness index' report of the Legatum Institute:
The results are in: Australia is the most prosperous country in the world; Yemen drags at the bottom of the list. But it's not just wealth that makes a country prosperous, according to the 2008 prosperity index, also known as the "happiness index," published last week by the Legatum Institute (LI) in Dubai (see www.prosperity.com). The institute based its rankings on surveys of economic competitiveness and comparative livability from 140 countries, including factors such as capital investment and the degree of social equality.You might enjoy playing with the 'prosperiscope' on the site.
This year, for the first time, countries' environmental efforts counted toward their scores, says LI Senior Vice President William Inboden. The institute selected an objective measurement--the ratio of developed land to land remaining in its natural state in each country--and added questions about how respondents felt about their country's environmental policies. Depending on a country's wealth, the environmental measures could count for as much as 4% of a country's prosperity score. Although Australia was the most prosperous country overall, New Zealand topped the environmental measures. The most environmentally unhappy people were Ukrainians, who particularly dislike their air quality.
"The Legatum Prosperiscope™ is a powerful interactive online tool that allows users to customise analyses across 104 countries using 22 different factors. Users can also compare countries against each other to identify their relative strengths and weaknesses. Follow the simple steps on the right to start using the Prosperiscope."
Posted by Deric Bownds at 5:15 AM
Tuesday, October 28, 2008
Natalie Angier does an interesting article on our instinctual intuitive math versus our more analytical learned number crunching, and the relationship between them. Apparently our evolutionarily endowed sense of approximation is related to how good we are at formal math. The article contains a neat interactive demonstration of our non verbal intuitive math abilities.
Brain imaging studies have traced the approximate number sense to a specific neural structure called the intraparietal sulcus, which also helps assess features like an object’s magnitude and distance. Symbolic math, by contrast, operates along a more widely distributed circuitry, activating many of the prefrontal regions of the brain that we associate with being human. Somewhere, local and global must be hooked up to a party line.
...open questions include how malleable our inborn number sense may be, whether it can be improved with training, and whether those improvements would pay off in a greater appetite and aptitude for math. If children start training with the flashing dot game at age 4, will they be supernumerate by middle school?
Here is the PDF from Science Magazine.
Monday, October 27, 2008
Recorded 10/25/08 on the Steinway B in my home on Twin Valley Road in Middleton, Wisconsin.
Here is the abstract of the article by Williams and Bargh which has the title of this post:
"Warmth" is the most powerful personality trait in social judgment, and attachment theorists have stressed the importance of warm physical contact with caregivers during infancy for healthy relationships in adulthood. Intriguingly, recent research in humans points to the involvement of the insula in the processing of both physical temperature and interpersonal warmth (trust) information. Accordingly, we hypothesized that experiences of physical warmth (or coldness) would increase feelings of interpersonal warmth (or coldness), without the person's awareness of this influence. In study 1, participants who briefly held a cup of hot (versus iced) coffee judged a target person as having a "warmer" personality (generous, caring); in study 2, participants holding a hot (versus cold) therapeutic pad were more likely to choose a gift for a friend instead of for themselves.
Metaphors such as icy stare depict social exclusion using cold-related concepts; they are not to be taken literally and certainly do not imply reduced temperature. Two experiments, however, revealed that social exclusion literally feels cold. Experiment 1 found that participants who recalled a social exclusion experience gave lower estimates of room temperature than did participants who recalled an inclusion experience. In Experiment 2, social exclusion was directly induced through an on-line virtual interaction, and participants who were excluded reported greater desire for warm food and drink than did participants who were included. These findings are consistent with the embodied view of cognition and support the notion that social perception involves physical and perceptual content. The psychological experience of coldness not only aids understanding of social interaction, but also is an integral part of the experience of social exclusion.More detail on the two experiments:
In one, they split 65 students into two groups, instructing those in one to recall a time when they felt socially rejected, and those in the other to summon a memory of social acceptance.
Many of the students were recent immigrants and had fresh memories of being isolated in the dorms, left behind while roommates went out, Dr. Zhong said.
The researchers then had each of the participants estimate the temperature in the lab room. The students who had recalled being excluded estimated the temperature to be, on average, 5 degrees Fahrenheit lower than the others.
In the second experiment, the researchers had 52 students come into the lab and play a computer game, one at a time. The students “threw” a ball back and forth with three other figures on the computer screen that — so the participants thought — represented other students playing from remote locations.
In fact a computer program was running the game, and it excluded half the study participants, throwing them the virtual ball a couple of times in the beginning, then ignoring them altogether. The other group of students in the study were included in the virtual game of catch.
After playing the game, the participants in this study then rated their preferences for a variety of foods and drinks, including hot soup, coffee, an apple and crackers. Those who had been isolated in the computer game showed a strong preference for the soup and coffee over the other items; the included students had no such preference.
Sunday, October 26, 2008
I'm struck by how very little I know about the ~10,000 visitors that Quantcast tells me come to Deric's MindBlog each month. Thus this essay in the "Lives" section of today's New York Times Magazine struck a chord with me.
Friday, October 24, 2008
I'm always being concerned in scanning journals for possible postings in this blog that my eye is too readily caught by the flashy marketing phrase or popularizing twist, thus neglecting more boring, but possibly much more significant, work. An article in The Economist reinforces my concern by pointing to work of Young Ioannidis, and Al-Ubaydli in PLos Medicine. that uses economic commodity theory to show how the current scientific publishing system is biased towards favoring trumpeted results that are also more likely to be false.
In economic theory the winner’s curse refers to the idea that someone who places the winning bid in an auction may have paid too much. Consider, for example, bids to develop an oil field. Most of the offers are likely to cluster around the true value of the resource, so the highest bidder probably paid too much.
The same thing may be happening in scientific publishing, according to a new analysis. With so many scientific papers chasing so few pages in the most prestigious journals, the winners could be the ones most likely to oversell themselves—to trumpet dramatic or important results that later turn out to be false. This would produce a distorted picture of scientific knowledge, with less dramatic (but more accurate) results either relegated to obscure journals or left unpublished.
It starts with the nuts and bolts of scientific publishing. Hundreds of thousands of scientific researchers are hired, promoted and funded according not only to how much work they produce, but also to where it gets published. For many, the ultimate accolade is to appear in a journal like Nature or Science. Such publications boast that they are very selective, turning down the vast majority of papers that are submitted to them.
The assumption is that, as a result, such journals publish only the best scientific work. But Dr Ioannidis and his colleagues argue that the reputations of the journals are pumped up by an artificial scarcity of the kind that keeps diamonds expensive. And such a scarcity, they suggest, can make it more likely that the leading journals will publish dramatic, but what may ultimately turn out to be incorrect, research.
For those of you who might be more heavily into philosophy of mind and introspective psychology, I want to pass along this PDF of a draft article that is to appear in Brain and Behavioral Sciences, "How we know our own minds: the relationship between mindreading and metacognition." Carruthers defends the idea that our knowledge of our own attitudes results from turning our mindreading capacities upon ourselves, not from introspection for propositional attitudes. Here is his abstract, showing the organization of his arguments:
Four different accounts of the relationship between third-person mindreading and first-person metacognition are compared and evaluated. While three of them endorse the existence of introspection for propositional attitudes, the fourth (defended here) claims that our knowledge of our own attitudes results from turning our mindreading capacities upon ourselves. Section 1 introduces the four accounts. Section 2 develops the “mindreading is prior” model in more detail, showing how it predicts introspection for perceptual and quasi-perceptual (e.g. imagistic) mental events while claiming that metacognitive access to our own attitudes always results from swift unconscious self-interpretation. It also considers the model’s relationship to the expression of attitudes in speech. Section 3 argues that the commonsense belief in the existence of introspection should be given no weight. Section 4 argues briefly that data from childhood development are of no help in resolving this debate. Section 5 considers the evolutionary claims to which the different accounts are committed, and argues that the three introspective views make predictions that aren’t borne out by the data. Section 6 examines the extensive evidence that people often confabulate when self-attributing attitudes. Section 7 considers “two systems” accounts of human thinking and reasoning, arguing that although there are inrospectable events within System 2, there are no introspectable attitudes. Section 8 examines alleged evidence of “unsymbolized thinking”. Section 9 considers the claim that schizophrenia exhibits a dissociation between mindreading and metacognition. Finally, Section 10 evaluates the claim that autism presents a dissociation in the opposite direction, of metacognition without mindreading.
Thursday, October 23, 2008
Choi et al. report an interesting study in the Journal of Neuroscience. I'm passing on the abstract and a bit of explanation of crystallized versus fluid intelligence, but not the usual flashy fMRI graphics:
We hypothesized that individual differences in intelligence (Spearman's g) are supported by multiple brain regions, and in particular that fluid (gF) and crystallized (gC) components of intelligence are related to brain function and structure with a distinct profile of association across brain regions. In 225 healthy young adults scanned with structural and functional magnetic resonance imaging sequences, regions of interest (ROIs) were defined on the basis of a correlation between g and either brain structure or brain function. In these ROIs, gC was more strongly related to structure (cortical thickness) than function, whereas gF was more strongly related to function (blood oxygenation level-dependent signal during reasoning) than structure. We further validated this finding by generating a neurometric prediction model of intelligence quotient (IQ) that explained 50% of variance in IQ in an independent sample. The data compel a nuanced view of the neurobiology of intelligence, providing the most persuasive evidence to date for theories emphasizing multiple distributed brain regions differing in function.As background:
gC, sometimes described as verbal ability, is more dependent on accumulated knowledge in long-term storage, including semantic memory. gF refers to reasoning ability, and is known to depend on working memory. Although gC and gF are typically correlated and can be considered subfactors of g (Jensen), they are conceptually and empirically separable. For instance, gC continues to increase over the lifespan, but gF peaks in early adulthood and then declines . Furthermore, at the neural level, lesion studies demonstrated that patients with anterior temporal damages perform poorly on tests of semantic knowledge, whereas prefrontal patients typically show profound deficits in solving diverse reasoning tasks.
I've mentioned the n-back task for improving working memory and intelligence in several - previous - posts. Kuriyama et al. now use this test to show that post-training sleep significantly enhances this improvement:
Working memory (WM) performance, which is an important factor for determining problem-solving and reasoning ability, has been firmly believed to be constant. However, recent findings have demonstrated that WM performance has the potential to be improved by repetitive training. Although various skills are reported to be improved by sleep, the beneficial effect of sleep on WM performance has not been clarified. Here, we show that improvement in WM performance is facilitated by posttraining naturalistic sleep. A spatial variant of the n-back WM task was performed by 29 healthy young adults who were assigned randomly to three different experimental groups that had different time schedules of repetitive n-back WM task sessions, with or without intervening sleep. Intergroup and intersession comparisons of WM performance (accuracy and response time) profiles showed that n-back accuracy after posttraining sleep was significantly improved compared with that after the same period of wakefulness, independent of sleep timing, subject's vigilance level, or circadian influences. On the other hand, response time was not influenced by sleep or repetitive training schedules. The present study indicates that improvement in n-back accuracy, which could reflect WM capacity, essentially benefits from posttraining sleep.
Wednesday, October 22, 2008
DeRubeis et al. offer an interesting review article in Nature Reviews Neuroscience on treatment outcomes and neural mechanisms, from which I pass on part of the abstract and some summary graphs:
Studies have shown that cognitive therapy is as efficacious as antidepressant medication at treating depression, and it seems to reduce the risk of relapse even after its discontinuation. Cognitive therapy and antidepressant medication probably engage some similar neural mechanisms, as well as mechanisms that are distinctive to each.
Cognitive therapy and antidepressant medication have comparable effects. This graph shows the response of outpatients who had moderate-to-severe depression to cognitive therapy (CT), antidepressant medication (ADM) or placebo. Patients who were assigned to ADM or to CT showed a significantly higher response rate after 8 weeks of treatment than those who were assigned to placebo. After 16 weeks of treatment the response rates of ADM and CT were almost identical.
Less relapse after cognitive therapy compared with antidepressant medication. The second phase of the parent antidepressant medication (ADM) versus cognitive therapy (CT) study followed patients who had responded to ADM or to CT3. Patients who had responded to ADM were randomly assigned to either continue ADM treatment for one year (beige and red lines) or to change to placebo treatment for 1 year (green line). Patients who responded to CT were allowed three sessions of CT during the 1-year continuation period. In the follow-up period, none of the patients received any treatment. The figure shows that prior treatment with CT protected against relapse of depression at least as well as the continued provision of ADM, and better than ADM treatment that was subsequently discontinued. Note that the patient group that was given ADM in the continuation year contained a number of patients who did not adhere to the medication regimen. The red line indicates the response of the ADM-continuation group including these non-compliant patients, whereas the beige line shows the response of the patients in this group after the non-compliant patients had been removed from the analysis.
After a graphic showing changes in blood-oxygen-level-dependent (BOLD) signal in response to cognitive and emotional tasks associated with cognitive therapy, the authors offer a summary hypothetical time course of the changes to amygdala and prefrontal function that are associated with antidepressant medication and cognitive therapy.
a | During acute depression, amygdala activity is increased (red) and prefrontal activity is decreased (blue) relative to activity in these regions in healthy individuals. b | Cognitive therapy (CT) effectively exercises the prefrontal cortex (PFC), yielding increased inhibitory function of this region. c | Antidepressant medication (ADM) targets amygdala function more directly, decreasing its activity. d | After ADM or CT, amygdala function is decreased and prefrontal function is increased. The double-headed arrow between the amygdala and the PFC represents the bidirectional homeostatic influences that are believed to operate in healthy individuals.
The Editor's choice section of science describes an interesting bit of work by Pitcher et al. showing the embodyment of our social cognition:
Humans are especially interested in faces, as a means of sending signals--witness the sizeable arc of somatosensory cortex devoted to representation of one's own face--and as a substrate for social cognition. Pitcher et al. describe results supporting theories of embodied cognition and emotion, which posit cognition and emotion as being shaped by our bodily movements and perceptions. They used repetitive transcranial magnetic stimulation (rTMS) to interfere with neural activity in the face areas of the somatosensory cortex while people discriminated the emotional expressions of faces (happy, sad, surprised, fearful, angry, and disgusted) and found that accuracy dropped significantly, as it also did when the occipital face area was similarly stimulated. The temporal sequence of neural processing was then delineated using double-pulse TMS, showing that the occipital area acted in the time window from 60 to 100 ms after the face stimulus was shown, whereas the somatosensory area was active a bit later, between 100 and 170 ms.
Tuesday, October 21, 2008
Here is a scary article.
Norenzayan and Shariff offer an interesting review article on empirical evidence for religious prosociality. Here is one clip and two figures from the article.
Agreement is emerging that selective pressures over the course of human evolution can explain the wide cross-cultural re-occurrence, historical persistence, and predictable cognitive structure of religious beliefs and behaviors. The tendency to detect agency in nature likely supplied the cognitive template that supports the pervasive belief in supernatural agents. These agents are widely believed to transcend physical, biological, and psychological limitations. However, other important details are subject to cultural variation. Although in many societies supernatural agents are not directly concerned with human morality, in many others, morally concerned agents use their supernatural powers to observe and, in some cases, to punish and reward human social interactions. Examples include the God of Abrahamic religions and Viracocha, the Incan supreme God, but also many morally concerned deities found in traditional societies, such as the adalo, ancestral spirits of the Kwaio Solomon islanders. These beliefs are likely to spread culturally to the extent that they facilitate ingroup cooperation. This could occur by conforming to individual psychology that favors reputation-sensitive prosocial tendencies, as the by-product account holds; by competition among social groups, as the cultural group selection account would suggest; or possibly by some combination of the two. Religious behaviors and rituals, if more costly to cooperating group members than to freeloaders, may have reliably signaled the presence of devotion and, therefore, cooperative intention toward ingroup members, in turn, buffering religious groups against defection from freeloaders and reinforcing cooperative norms. Religious prosociality, thus, may have softened the limitations that kinship-based and (direct or indirect) reciprocity-based altruism place on group size. In this way, the cultural spread of religious prosociality may have facilitated the rise of stable, large, cooperative communities of genetically unrelated individuals.
Figure - Implicit activation of God concepts, relative to a neutral prime, increased offers in the one-shot, anonymous Dictator Game. Priming secular concepts indicating moral authority had a similar effect. The results showed not only a quantitative increase in generosity, but also a qualitative shift in social norms. In the control group, the modal response was selfishness, a plurality of players pocketed all $10. In the God group, the mode shifted to fairness, a plurality of players split the money evenly (N = 75). It remains to be seen, however, whether these effects
would occur if the recipient was clearly marked as an outgroup member.
Figure - Life expectancy of religious versus secular communes. An analysis of 200 religious and secular communes in 19th-century America (29), for every year of their life course, religious communes were about four times as likely to survive than their secular counterparts. This difference remained after statistically controlling for type of commune movement, year founded, and year at risk of dissolution (the last control assesses major historical trends that may independently impact commune dissolution).
An article by Pies with the title of this post is worth reading. It deals with the criticism that modern psychiatric practice, in collusion with pill pushing pharmaceutical companies, has medicalized “normal sadness” brought on by external circumstances. (Added note: Pies has emailed this this link to a more detailed discussion posted on the PsychCentral website.) Here are some clips from the NYTimes article:
In their recent book “The Loss of Sadness” (Oxford, 2007), Allan V. Horwitz and Jerome C. Wakefield assert that for thousands of years, symptoms of sadness that were “with cause” were separated from those that were “without cause.” Only the latter were viewed as mental disorders.
With the advent of modern diagnostic criteria, these authors argue, doctors were directed to ignore the context of the patient’s complaints and focus only on symptoms — poor appetite, insomnia, low energy, hopelessness and so on. The current criteria for major depression, they say, largely fail to distinguish between “abnormal” reactions caused by “internal dysfunction” and “normal sadness” brought on by external circumstances. And they blame vested interests — doctors, researchers, pharmaceutical companies — for fostering this bloated concept of depression.
But while this increasingly popular thesis contains a kernel of truth, it conceals a bushel basket of conceptual and scientific problems.
For one thing, if modern diagnostic criteria were converting mere sadness into clinical depression, we would expect the number of new cases of depression to be skyrocketing compared with rates in a period like the 1950s to the 1970s. But several new studies in the United States and Canada find that the incidence of serious depression has held relatively steady in recent decades.
Second, it may seem easy to determine that someone with depressive complaints is reacting to a loss that touched off the depression. Experienced clinicians know this is rarely the case.
Third, and perhaps most troubling, is the implication that a recent major loss makes it more likely that the person’s depressive symptoms will follow a benign and limited course, and therefore do not need medical treatment. This has never been demonstrated, to my knowledge, in any well-designed studies. And what has been demonstrated, in a study by Dr. Sidney Zisook, is that antidepressants may help patients with major depressive symptoms occurring just after the death of a loved one.
Monday, October 20, 2008
Small and Vorgan offer an engaging article in Scientific American Mind on how daily exposure to television, computers, smart phones, video games, search engines and web browsers is rewiring our brains. A modern generation is rising with brains that are very different from the brains of those of us whose basic brain wiring was laid down in a time when direct social interactions were more the norm. One of the authors (Small) compared brain activities in computer- savvy versus computer-naive 50-60 year olds while searching for accurate information on a topic using Google, subtracting activity associated with just reading a text to determine activity specific to the searching function (which was the same in the two groups). In the baseline scanning session during searching on Google, the computer-savvy subjects engaged their dorsolateral prefrontal cortex while the Internet-naive subjects showed minimal activation in this region. After just five days of practice,the exact same neural circuitry in the front part of the brain became active in the Internet-naive subjects. Five hours on the Internet, and these participants had already rewired their brains.
Our high-tech revolution has plunged us into a state of “continuous partial attention,” which software executive Linda Stone, who coined the term in 1998, describes as continually staying busy—keeping tabs on everything while never truly focusing on anything. Continuous partial attention differs from multitasking, wherein we have a purpose for each task and we are trying to improve efficiency and productivity. Instead, when our minds partially attend, and do so continuously, we scan for an opportunity for any type of contact at every given moment. We virtually chat as our text messages flow, and we keep tabs on active buddy lists (friends and other screen names in an instant message program); everything, everywhere, is connected through our peripheral attention. Although having all our pals online from moment to moment seems intimate, we risk losing personal touch with our real-life relationships and may experience an artificial sense of intimacy as compared with when we shut down our devices and devote our attention to one
individual at a time.
When paying continuous partial attention, people may place their brain in a heightened state of stress. They no longer have time to reflect, contemplate or make thoughtful decisions. Instead they exist in a sense of constant crisis—on alert for a new contact or bit of exciting news or information at any moment. Once people get used to this state, they tend to thrive on the perpetual connectivity. It feeds their ego and sense of self-worth, and it becomes irresistible. Neuroimaging studies suggest that this sense of selfworth may protect the size of the hippocampus—the horseshoeshaped brain region in the medial (inward-facing) temporal lobe, which allows us to learn and remember new information. Psychiatry professor Sonia J. Lupien and her associates at McGill University studied hippocampal size in healthy younger and older adult volunteers. Measures of self esteem correlated significantly with hippocampal size, regardless of age. They also found that the more people felt in control of their lives, the larger the hippocampus. But at some point, the sense of control and self-worth we feel when we maintain continuous partial attention tends to break down—our brains were not built to sustain such monitoring for extended periods. Eventually the hours of unrelenting digital connectivity can create a unique type of brain strain. Many people who have been working on the Internet for several hours without a break report making frequent errors in their work. On signing off, they notice feeling spaced out, fatigued, irritable and distracted, as if they are in a “digital fog.” This new form of mental stress, what Small terms “techno-brain burnout,” is threatening to become an epidemic. Under this kind of stress, our brains instinctively signal the adrenal gland to secrete cortisol and adrenaline. In the short run, these stress hormones boost energy levels and augment memory, but over time they actually impair cognition, lead to depression, and alter the neural circuitry in the hippocampus, amygdala and prefrontal cortex—the brain regions that control mood and thought. Chronic and prolonged techno-brain burnout can even reshape the underlying brain structure.
While the brains of today’s digital natives are wiring up for rapid-fire cyber searches, however, the neural circuits that control the more traditional learning methods are neglected and gradually diminished. The pathways for human interaction and communication weaken as customary one-on-one people skills atrophy. Our U.C.L.A. research team and other scientists have shown that we can intentionally alter brain wiring and reinvigorate some of these dwindling neural pathways, even while the newly evolved technology circuits bring our brains to extraordinary levels of potential.
From the "Random Samples" section of the Oct. 17 Science Magazine:
In the winner-take-all world of politics, candidates know that even a modest lead in the polls can spell almost certain victory. Sheldon Jacobson, an operations research specialist at the University of Illinois, Urbana-Champaign, and colleagues, including a group of students, have attempted to quantify that insight for the current United States presidential election, putting their predictions for the Electoral College on a Web site, election08.cs.uiuc.edu. Using a statistical method known as Bayesian estimation, they combined an analysis of results from the 2004 Bush-versus-Kerry contest with current state-by-state polls for Obama versus McCain to produce probabilities for each candidate of carrying each state. They then converted the estimates into a probability distribution for the total number of Electoral College votes a candidate might receive. In Indiana, for example, polls as of 4 October gave McCain a slight 2.5% lead. But given that Bush carried Indiana in 2004 by 20.7%, a Bayesian calculation indicates McCain's chance of winning the state's 11 Electoral College votes at about 87%. Most states are now in the bag for one candidate or the other; only a handful are truly in Bayesian play. Current calculations give McCain no chance of victory. "However," Jacobson cautions, "if the polls move, then so will our forecasts."
Friday, October 17, 2008
Richard Dooloing writes on how a physicist, a wizard and a serial killer warned us of the current financial crisis.
We are living, we have long been told, in the Information Age. Yet now we are faced with the sickening suspicion that technology has run ahead of us. Man is a fire-stealing animal, and we can’t help building machines and machine intelligences, even if, from time to time, we use them not only to outsmart ourselves but to bring us right up to the doorstep of Doom.
We are still fearful, superstitious and all-too-human creatures. At times, we forget the magnitude of the havoc we can wreak by off-loading our minds onto super-intelligent machines, that is, until they run away from us, like mad sorcerers’ apprentices, and drag us up to the precipice for a look down into the abyss.
As the financial experts all over the world use machines to unwind Gordian knots of financial arrangements so complex that only machines can make — “derive” — and trade them, we have to wonder: Are we living in a bad sci-fi movie? Is the Matrix made of credit default swaps?
When Treasury Secretary Paulson (looking very much like a frightened primate) came to Congress seeking an emergency loan, Senator Jon Tester of Montana, a Democrat still living on his family homestead, asked him: “I’m a dirt farmer. Why do we have one week to determine that $700 billion has to be appropriated or this country’s financial system goes down the pipes?”
“Well, sir,” Mr. Paulson could well have responded, “the computers have demanded it.”
Posted by Deric Bownds at 5:45 AM
Berchtold et al. pack quite a lot of interesting information into their abstract describing work on sexually dimorphic gene expression changes during human aging. I'm right in the middle of this quote: "Prominent change occurred in the sixth to seventh decades across cortical regions, suggesting that this period is a critical transition point in brain aging, particularly in males." Here is the abstract:
Gene expression profiles were assessed in the hippocampus, entorhinal cortex, superior-frontal gyrus, and postcentral gyrus across the lifespan of 55 cognitively intact individuals aged 20–99 years. Perspectives on global gene changes that are associated with brain aging emerged, revealing two overarching concepts. First, different regions of the forebrain exhibited substantially different gene profile changes with age. For example, comparing equally powered groups, 5,029 probe sets were significantly altered with age in the superior-frontal gyrus, compared with 1,110 in the entorhinal cortex. Prominent change occurred in the sixth to seventh decades across cortical regions, suggesting that this period is a critical transition point in brain aging, particularly in males. Second, clear gender differences in brain aging were evident, suggesting that the brain undergoes sexually dimorphic changes in gene expression not only in development but also in later life. Globally across all brain regions, males showed more gene change than females. Further, Gene Ontology analysis revealed that different categories of genes were predominantly affected in males vs. females. Notably, the male brain was characterized by global decreased catabolic and anabolic capacity with aging, with down-regulated genes heavily enriched in energy production and protein synthesis/transport categories. Increased immune activation was a prominent feature of aging in both sexes, with proportionally greater activation in the female brain. These data open opportunities to explore age-dependent changes in gene expression that set the balance between neurodegeneration and compensatory mechanisms in the brain and suggest that this balance is set differently in males and females, an intriguing idea.
Thursday, October 16, 2008
I just received an email from Andrew Werth regarding the previous post. Andrew is a former software engineer turned artist whose paintings are about perception and embodiment. I thought I would pass on this link to his website, which lets one view paintings in his Embodyment Series.
I thought I would pass along portions of a review in Science by Harold Fromm which has the title of this post, of Edward Slingerland's new book, "What Science Offers the Humanities - Integrating Body and Culture."
...his overall task is to address the befuddled dualism that still dominates most of our intellectual disciplines...Slingerland's central theme is that everything human has evolved in the interests of the materiality of the body. He identifies objectivist realism and postmodern relativity, both insufficiently attentive to the body, as the major epistemologies to be swept away, followed by the dualism of body and soul. For Slingerland, the presiding genii behind such a cleansing are George Lakoff and Mark Johnson, with heavier debts to Johnson [whose terse summary of embodiment in (1) appeared too late for Slingerland to reference]. They view all thought and human behavior as generated by the body and expressed as conceptual metaphors that translate physical categories (such as forward, backward, up, and down) into abstract categories (such as progress, benightedness, divinity, immorality). These body-driven metaphors, Slingerland writes, are a "set of limitations on human cognition, constraining human conceptions of entities, categories, causation, physics, psychology, biology, and other humanly relevant domains."
The supposedly objective world is not "some preexisting object out there in the world, with a set of invariant and observer-independent properties, simply waiting to be found the way one finds a lost sock under the bed." All we can ever see or understand is what our own bodily faculties permit via the current structure of the brain.
In opposition to objective realism, postmodern relativity regards language and culture as constituting the only "real" world possible for us. It posits an endless hall of mirrors with no access to outside--epitomized by Derrida's notorious remark that there is nothing (at least for humans) outside of texts (i.e., culture). This view, which dominated the humanities for several decades, is mercifully beginning to fade as the cognitive sciences have matured and are increasingly promulgated.
Even though the knowing human subject is itself just a thing and not an immaterial locus of reason, the universe it experiences is as real and functional for us as any "thing" could possibly be. We do get some things "right," even if we can never know the noumenal genesis behind our knowledge. And the very concept of noumena (things in themselves independent of any observer) now seems somewhat obsolete, given that the intuition of discrete, self-bounded "things" is as built-in to the human psyche as the Kantian intuitions of space and time, grounding all experience.
Our million billion synapses produce a "person" with the illusion of a self. Slingerland holds that "we are robots designed to be constitutionally incapable of experiencing ourselves and other conspecifics as robots." Our innate and overactive theory of mind (that other people, like ourselves, have "intentions") projects agency onto everything--in the past, even onto stones and trees. The "hard problem" for philosophy of consciousness (to use David Chalmers's phrase) remains: what are thoughts, cogitations, thinkers, qualia? Chalmers's solution, alas, swept away Cartesian dualism only to sneak his own magic spook, conscious experience (for him, on par with mass, charge, and space-time), in through the back door (2, 3).
Slingerland starts with Darwin and eventually follows Daniel Dennett so far as to agree that consciousness can be done full justice through third-person descriptions that require no mysterious, unaccounted-for, nonmaterial, first-person entity as substrate. Thus the famous "Mary," who intellectually knows everything there is to know about color despite having been sequestered for life in a color-free lab, will recognize red the first time she steps outside (4). And Thomas Nagel's famous bats don't know anything about bathood that we can't figure out for ourselves from observation (5). No first-person construct, no locus of consciousness, need be invoked.
The next step, if you want to go so far (the jury is out), is to eliminate consciousness altogether, because there's nothing for it to do that can't be done without it. And with it, you need a spook to keep the show on the road. Choose your insoluble problem: eliminate consciousness altogether as superfluous or explain it (if there's really a you who makes such choices). Slingerland prefers the first option.
His conclusion, which I can hardly do justice to here, is relatively satisfying. He notes that although we don't have great difficulty knowing that Earth revolves around the Sun while feeling that the Sun is rising and setting (Dennett's favorite example of folk psychology), "no cognitively undamaged human being can help acting like and at some level really feeling that he or she is free"--however nonsensical the notion of agencyless free will (i.e., "choices" without a self to make them). Still, once the corrosive acid of Darwinism [to use Dennett's figure from (6)] has resolved the body-mind dualism into body alone, some but not most of us are able "to view human beings simultaneously under two descriptions: as physical systems and as persons."
1. M. Johnson, The Meaning of the Body: Aesthetics of Human Understanding (Univ. of Chicago Press, Chicago, 2007).
2. D. J. Chalmers, J. Consciousness Stud. 2, 200 (1995).
3. D. J. Chalmers, The Conscious Mind: In Search of a Fundamental Theory (Oxford Univ. Press, Oxford, 1996).
4. F. Jackson, Philos. Q. 32, 127 (1982).
5. T. Nagel, Philos. Rev. 83, 435 (1974).
6. D. C. Dennett, Darwin's Dangerous Idea: Evolution and the Meaning of Life (Simon and Schuster, New York, 1995).
Overactive bladder, usually caused by bladder obstruction in males, apparently affects ~17% of the population, towards whom those awful pharmaceutical television adds are directed. Signals arising from bladder or colonic pathology are processed by the cortex and can potentially be expressed as central symptoms (e.g., hyperarousal, attention disorders, anxiety) that occur alongside the visceral pathology. Rickenbacher et al. now show, in a rat model, that bladder obstruction not only botches up the bladder, but also brain regions involved in its regulation.
Neural circuits that allow for reciprocal communication between the brain and viscera are critical for coordinating behavior with visceral activity. At the same time, these circuits are positioned to convey signals from pathologic events occurring in viscera to the brain, thereby providing a structural basis for comorbid central and peripheral symptoms. In the pons, Barrington's nucleus and the norepinephrine (NE) nucleus, locus coeruleus (LC), are integral to a circuit that links the pelvic viscera with the forebrain and coordinates pelvic visceral activity with arousal and behavior. Here, we demonstrate that a prevalent bladder dysfunction, produced by partial obstruction in rat, has an enduring disruptive impact on cortical activity through this circuit. Within 2 weeks of partial bladder obstruction, the activity of LC neurons was tonically elevated. LC hyperactivity was associated with cortical electroencephalographic activation that was characterized by decreased low-frequency (1–3 Hz) activity and prominent theta oscillations (6–8 Hz) that persisted for 4 weeks. Selective lesion of the LC–NE system significantly attenuated the cortical effects. The findings underscore the potential for significant neurobehavioral consequences of bladder disorders, including hyperarousal, sleep disturbances, and disruption of sensorimotor integration, as a result of central noradrenergic hyperactivity. The results further imply that pharmacological manipulation of central NE function may alleviate central sequelae of these visceral disorders.
Wednesday, October 15, 2008
Bajaj does an interesting writeup of well-known crowd psychological dynamics behind recent "irrational" drops in the stock market. Fear is a more powerful force than greed. Our aversive reaction to losing $1000 is greater than our pleasure at earning the same amount...
fear now seems to rule, with investors often exhibiting a Wall Street version of the fight-or-flight mechanism — selling first, and asking questions later...some analysts are starting to suggest the markets are showing signs of “capitulation” — what happens when even the bullish holdouts, the unflagging optimists, throw up their hands and join the stampede out of the market...To some, signs of capitulation can be read as an indicator that the bottom may be near.The opposite swing of the cycle is buying at the top of a bubble. I remember during my winter stays in Ft. Lauderdale in 2005 and 2006, every fourth person I chatted with seemed to be a realtor and dinner conversations were dominated by stories about fast profits on flipped condominiums.
An article by Wapner points to the work of James Pennebacker and his Wordwatchers blog that is tracking the candidates use of words during the 2008 election. The blog makes fascinating reading. Here is just one clip:
Predicting how they will govern. Most language dimensions that we study are probably better markers of how people will lead than who will vote for them. Some dimensions that are relevant include:
Cognitive complexity. A particularly reliable marker of cognitive complexity is the exclusive word dimension. Exclusive words such as but, except, without, exclude, signal that the speaker is making an effort to distinguish what is in a category and not in a category. Those who use more exclusive words make better grades in college, are more honest in lab studies, and have more nuanced understanding of events and people. Through the primaries until now, Obama has consistently been the highest in exclusive word use and McCain the lowest.
Categorical versus fluid thinking. Some people naturally approach problems by assigning them to categories. Categorical thinking involves the use of articles (a, an, the) and concrete nouns. Men, for example, use articles at much higher rates than women. Fluid thinking involves describing actions and changes, often in more abstract ways. A crude measure of fluid thinking is the use of verbs. Women use verbs more than men.
McCain and Obama could not be more different in their use of articles and verbs. McCain uses verbs at an extremely low rate and articles at a fairly high rate. Obama, on the other hand, is remarkably high in his use of verbs and low in his use of articles. These patterns suggest that McCain’s natural way of understanding the world is to first label the problem and find a way to put it into a pre-existing category. Obama is more likely to define the world as ongoing actions or processes.
Personal and socially connected. Individuals who think about and try to connect with others tend to use more personal pronouns (I, we, you, she, they) than those who are more socially detached. Bush was higher than Kerry or Gore. McCain has consistently been much higher than any other candidate in this election cycle. His use of 1st person singular (I, me, my) is particularly high which often signals an openness and honesty. Obama uses personal pronouns at moderate levels - similar to Hillary Clinton and most other primary candidates of both parties.
Restrained versus impulsive. People vary in the degree to which they act quickly or shoot from the hip versus stand back and consider their options. Over the last few years, some have argued that the use of negations (e.g., no, not, never) indicate a sign of inhibition or constraint. Low use of negations may be linked to impulsiveness. Bush was low in negations whereas Kerry was quite high. Across the election cycle, Obama has consistently been the highest user of negations - suggesting a restrained approach - where as McCain has been the lowest - a more impulsive way of dealing with the world.
Tuesday, October 14, 2008
Kédia et al. perform brain imaging of subjects as they imagine harm in several different contexts of subject and victim:
The statement "An agent harms a victim" depicts a situation that triggers moral emotions. Depending on whether the agent and the victim are the self or someone else, it can lead to four different moral emotions: self-anger ("I harm myself"), guilt ("I harm someone"), other-anger ("someone harms me"), and compassion ("someone harms someone"). In order to investigate the neural correlates of these emotions, we examined brain activation patterns elicited by variations in the agent (self vs. other) and the victim (self vs. other) of a harmful action. Twenty-nine healthy participants underwent functional magnetic resonance imaging while imagining being in situations in which they or someone else harmed themselves or someone else. Results indicated that the three emotional conditions associated with the involvement of other, either as agent or victim (guilt, other-anger, and compassion conditions), all activated structures that have been previously associated with the Theory of Mind (ToM, the attribution of mental states to others), namely, the dorsal medial prefrontal cortex, the precuneus, and the bilateral temporo-parietal junction. Moreover, the two conditions in which both the self and other were concerned by the harmful action (guilt and other-anger conditions) recruited emotional structures (i.e., the bilateral amygdala, anterior cingulate, and basal ganglia). These results suggest that specific moral emotions induce different neural activity depending on the extent to which they involve the self and other.
A clip from Steve Nadis' write up in Nature News of this year's Ig-Noble prizes:
Slime moulds exhibit the kind of "contemplative behaviour" that Hamlet is famous for, muses Toshiyuki Nakagaki of Hokkaido University in Japan. ...The slime mold's puzzle-solving ability — Shakespearean or otherwise — is a discovery that is unlikely to change the world, but it won Nakagaki and his colleagues an Ig Nobel Prize for cognitive science last week at the annual event held at Harvard University in Cambridge, Massachusetts. Their research... showed that slime molds looking for food have "the ability to find the minimum-length solution between two points in a labyrinth".
Subsequently, the team has found that molds can find the shortest path between 30–50 points, which is something even supercomputers cannot yet work out. "We can't even check the mold's solution," notes Nakagaki, "but it looks good."
Monday, October 13, 2008
Rolls et al. do a piece of work on how selective attention to affective value can alter how our brains process olfactory stimuli:
How does selective attention to affect influence sensory processing? In a functional magnetic resonance imaging investigation, when subjects were instructed to remember and rate the pleasantness of a jasmin odor, activations were greater in the medial orbitofrontal and pregenual cingulate cortex than when subjects were instructed to remember and rate the intensity of the odor. When the subjects were instructed to remember and rate the intensity, activations were greater in the inferior frontal gyrus. These top–down effects occurred not only during odor delivery but started in a preparation period after the instruction before odor delivery, and continued after termination of the odor in a short-term memory period. Thus, depending on the context in which odors are presented and whether affect is relevant, the brain prepares itself, responds to, and remembers an odor differently. These findings show that when attention is paid to affective value, the brain systems engaged to prepare for, represent, and remember a sensory stimulus are different from those engaged when attention is directed to the physical properties of a stimulus such as its intensity. This differential biasing of brain regions engaged in processing a sensory stimulus depending on whether the cognitive demand is for affect-related versus more sensory-related processing may be an important aspect of cognition and attention. This has many implications for understanding the effects not only of olfactory but also of other sensory stimuli.
Ashwin et al. have come up with a fascinating observation during their testing of 15 men with autism-spectrum disorders using the Freiburg Visual Acuity and Contrast Test. They found them to have, on average, 20:7 vision. This means they can see the same detail on an object 20 meters away that a person with average vision can see at 7 meters. Birds of prey have roughly 20:6 vision. What gives these people with autism hawk-like vision isn't known.
Friday, October 10, 2008
The research highlights section of Nature points to work by Bereczkei and his colleagues at the University of Pécs in Hungary who find new evidence linking partner choices to parental appearance. By measuring 14 facial proportions of 312 adults from 52 families, Bereczkei et al. show significant correlations in appearance between young men and their partner's father and young women and their partner's mother. This supports the theory that children are imprinted with their opposite-sex parent's face. The abstract from Proc. Roy. Soc. B:
Former studies have suggested that imprinting-like processes influence the shaping of human mate preferences. In this study, we provide more direct evidence for assessing facial resemblance between subjects' partner and subjects' parents. Fourteen facial proportions were measured on 312 adults belonging to 52 families, and the correlations between family members were compared with those of pairs randomly selected from the population. Spouses proved to be assortatively mated in the majority of measured facial proportions. Significant correlations have been found between the young men and their partner's father (but not his mother), especially on facial proportions belonging to the central area of the face. Women also showed resemblance to their partner's mother (but not to their father) in the facial characteristics of their lower face. Replicating our previous studies, facial photographs of participants were also matched by independent judges who ascribed higher resemblance between partners, and subjects and their partners' opposite-sex parents, compared with controls. Our results support the sexual imprinting hypothesis which states that children shape a mental template of their opposite-sex parents and search for a partner who resembles that perceptual schema. The fact that only the facial metrics of opposite-sex parents showed resemblance to the partner's face tends to rule out the role of familiarity in shaping mating preferences. Our findings also reject several other rival hypotheses. The adaptive value of imprinting-related human mating is discussed, and a hypothesis is made of why different facial areas are involved in males' and females' search for resemblance.
In a former life, I spent 30 years running a laboratory that studies how light is changed into a nerve signal in our eyes. Much of our work centered on the visual pigment rhodopsin, which starts an excitation cascade after its excitation by light by binding to the alpha subunit of a G-protein. I am in awe of new technologies that have, since my work, revealed many of the finer details of this process. Thus I can't resist showing this beautiful graphic from a recent review by Schwartz and Hubbell, describing work by Sheerer et al.
a, Rhodopsin, shown here in its inactivated conformation, is a light-sensing receptor found in cell membranes. It consists of a protein (opsin, green) and a ligand (retinal, pink, also shown in its inactivated conformation). When activated by light, rhodopsin binds to part of an adjacent G protein (binding region in red), triggering a cascade of biological responses. The protein plug (blue) is part of the extracellular domain of opsin, and immobilizes the extracellular transmembrane segments of the receptor. b, Scheerer et al. have determined the activated structure of opsin in complex with the receptor-binding peptide fragment of the G protein (the Galpha peptide). The most notable difference when compared with the inactivated receptor is that transmembrane helix 6 (TM-VI) has moved substantially outward (indicated by the red arrow), thereby creating the binding pocket for the G-protein peptide.
Thursday, October 09, 2008
Here is an interesting article on the resistance of economic theorists to using modeling approaches that have proven useful in predicting dramatic and sudden transitions. Such models have been successfully applied to predicting heart attacks, epileptic seizures, stock market bubbles, eutrophication of lakes, etc. They are based in part on the observation that variance in an apparent steady state begins to change in predictable ways in advance of large rapid transitions. Modeling the dynamics of a systems of agents by simulating their workings from the bottom up can reveal how instabilities or phase transitions can rise in a system of linked agents by trouble in one of them.
Science Magazine and the National Science Foundation have announced the winners and honorable mentions in the categories of photography, illustration, informational graphics, interactive media, and noninteractive media in this year's International Science & Engineering Visualization Challenge. The first place was this image of diatoms from the Mediterranean off the coast of Italy.
Wednesday, October 08, 2008
Benedict Carey has a great article in last Tuesday's NYTimes science section on the evolved psychology of retaliation and forgiveness we share with a large number of other social animal species, particularly with reference to the current public anger at the financial community:
The fury is based in instincts that have had a protective and often stabilizing effect on communities throughout human history. Small, integrated groups in particular often contain members who will stand up and — often at significant risk to themselves — punish cheaters, liars and freeloaders...The catch in this highly sensitive system, most researchers agree, is that it most likely evolved to inoculate small groups against invasive rogues, and not to set right the excesses of a vast and wildly diverse community like the American economy. Some experts believe that Japan’s disastrous delay in bailing out its banks in the early 1990s was caused in part by a collective urge to punish corrupt bankers, and they fear a similar outcome today.Carey describes a variety of investment game experiments that probe, for example, how our retribution behaviors depend on whether we are being observed by others.
Some experiments very relevant to our current economic chaos are reported by Whitson and Galinsky, who show that when we feel out of control, our need to impose order and rationale is strong enough cause us to see patterns where they do not exist, or conspiracies where there are none.
We present six experiments that tested whether lacking control increases illusory pattern perception, which we define as the identification of a coherent and meaningful interrelationship among a set of random or unrelated stimuli. Participants who lacked control were more likely to perceive a variety of illusory patterns, including seeing images in noise, forming illusory correlations in stock market information, perceiving conspiracies, and developing superstitions. Additionally, we demonstrated that increased pattern perception has a motivational basis by measuring the need for structure directly and showing that the causal link between lack of control and illusory pattern perception is reduced by affirming the self. Although these many disparate forms of pattern perception are typically discussed as separate phenomena, the current results suggest that there is a common motive underlying them.
Tuesday, October 07, 2008
I began a course called "The Biology of Mind" at the University of Wisconsin Madison in 1993, cross listed between the departments of Zoology, Psychology, Anthropology, and Neuroscience. The links to my personal website in the left column of this blog describe that course, whose lecture notes generated the "Biology of Mind" book. On my retirement in 2001, I was very grateful that John Hawks of the UW Anthropology Dept. took over the course, putting his own particular stamp on its contents. He has tried a number of innovations, such as podcasts of the lectures, and now has set up a blog on which students post their writing and commentary. It makes a fascinating read. Here is John's description of the effort:
I am doing a unique experiment with my course this semester, "Biology of Mind." The course has a history of collaborative peer review on writing assignments, and the students do a lot of writing -- students who earn an "A" in the course will be required to produce 10,000 words of written assignments during the semester. In the past, I have used the university's online course system to administer the assignments, and the students have really benefited from their peers' feedback as well as my own.
This semester, I've decided to take it all public. The students are collaborating as before, except this semester they are doing it on a blog. The blog's name is "Biology of Mind", and it has been up and running for a couple of weeks. Right now there are over 200 posts over there, and the number continues to grow.
The students write weekly reviews of papers in psychology, neuroscience, evolutionary biology, philosophy of mind, and naturally anthropology -- a broad scope. Many of the students have been following new research, others have chosen to delve more deeply into the history of one or more fields. In any event, if you're interested in the brain, you may like this site. I think the students (mostly seniors with some graduate students) are producing some nice work, and the site is open for feedback from the public as well.
In the Sept 23 issue of PNAS Brady et al. make some striking observations on the capacity of our visual memory stores:
One of the major lessons of memory research has been that human memory is fallible, imprecise, and subject to interference. Thus, although observers can remember thousands of images, it is widely assumed that these memories lack detail. Contrary to this assumption, here we show that long-term memory is capable of storing a massive number of objects with details from the image. Participants viewed pictures of 2,500 objects over the course of 5.5 h. Afterward, they were shown pairs of images and indicated which of the two they had seen. The previously viewed item could be paired with either an object from a novel category, an object of the same basic-level category, or the same object in a different state or pose. Performance in each of these conditions was remarkably high (92%, 88%, and 87%, respectively), suggesting that participants successfully maintained detailed representations of thousands of images. These results have implications for cognitive models, in which capacity limitations impose a primary computational constraint (e.g., models of object recognition), and pose a challenge to neural models of memory storage and retrieval, which must be able to account for such a large and detailed storage capacity.
Figure: Example test pairs presented during the two-alternative forced-choice task for all three conditions (novel, exemplar, and state). The number of observers reporting the correct item is shown for each of the depicted pairs.
The floating fractal (top, left) is formed 90 seconds after a drop of instant coffee falls into a cup of milk.
Coffee is heavier than milk and the battle between gravity and surface tension plays out at the boundary between the two liquids. The coffee falls vertically through the milk (bottom, left, with water replacing milk for ease of viewing), and the fractal pattern emerges.
The pattern constantly shifts as parts of it are sucked into the milk, producing a fractal structure with the same dimension as a Sierpi´nski carpet — formed when a square is cut into nine identical squares; the central square is removed; and the procedure is repeated with the remaining eight squares and so on infinitely.
Michiko Shimokawa and Shonosuke Ohta, fluid scientists at Kyushu University in Fukuoka City, Japan, say that it is the first time this kind of fractal has been shown experimentally (http://www.arxiv.org/abs/0809.2458), and they managed to recreate the process using a magnetic liquid instead of coffee (far right).
Posted by Deric Bownds at 5:00 AM
Monday, October 06, 2008
Yesterday was a rainy afternoon at my home on Twin Valley Road in Middleton Wisconsin, so I decided to a video recording of a relatively tranquil, lyrical piece by Edvard Grieg that I enjoy playing - the Air from his Holberg Suite.
Not exactly surprising, but fascinating never the less, from Oxley et al.
Although political views have been thought to arise largely from individuals' experiences, recent research suggests that they may have a biological basis. We present evidence that variations in political attitudes correlate with physiological traits. In a group of 46 adult participants with strong political beliefs, individuals with measurably lower physical sensitivities to sudden noises and threatening visual images were more likely to support foreign aid, liberal immigration policies, pacifism, and gun control, whereas individuals displaying measurably higher physiological reactions to those same stimuli were more likely to favor defense spending, capital punishment, patriotism, and the Iraq War. Thus, the degree to which individuals are physiologically responsive to threat appears to indicate the degree to which they advocate policies that protect the existing social structure from both external (outgroup) and internal (norm-violator) threats.
Friday, October 03, 2008
It turns out that we can learn to assess risks on the basis of visual hints we are not aware of seeing. In other words, without conscious processing of contextual cues, our brains can learn their reward value and use them to provide a bias on decision making. Functional neuroimaging reveals a correlation of cue values and prediction errors with activity in ventral striatum during conditioning. From the summary in Nature:
Mathias Pessiglione et al. repeatedly showed 20 subjects abstract symbols as they played a gambling game. Each symbol presentation involved one of three choices and was followed by a 'masking image' in a series that flickered so fast that the subjects could not consciously perceive the symbol shapes. The subjects were told that the symbols were associated with winning or losing, and then allowed to gamble.
The subjects won more than they lost, indicating that their brains recognized the unperceived symbols and learned to associate them with reward or punishment. Functional neuroimaging showed that the mechanism involves the ventral striatum (see figure), a brain area associated with assessing reward value.
Estrogens are known to increase the number of excitatory synapses in our hippocampus and enhance both cognitive performance and spatial memory. This is why there is such interest in the possible disruptive effects of estrogenic compounds in the environment, particularly bisphenol A (BPA) that is present in some plastics. Leranth et al. now demonstrate in monkeys that a daily dose of BPA considered within the safe range for humans (50 μg/kg) completely blocks the estradiol-induced increase in axospinous synapses in three distinct fields of the hippocampus. This would be expected to have profound effects on the highly plastic excitatory (glutamatergic) circuits in both our hippocampus and prefrontal cortex. Here is their chilling abstract:
Exposure measurements from several countries indicate that humans are routinely exposed to low levels of bisphenol A (BPA), a synthetic xenoestrogen widely used in the production of polycarbonate plastics. There is considerable debate about whether this exposure represents an environmental risk, based on reports that BPA interferes with the development of many organs and that it may alter cognitive functions and mood. Consistent with these reports, we have previously demonstrated that BPA antagonizes spine synapse formation induced by estrogens and testosterone in limbic brain areas of gonadectomized female and male rats. An important limitation of these studies, however, is that they were based on rodent animal models, which may not be representative of the effects of human BPA exposure. To address this issue, we examined the influence of continuous BPA administration, at a daily dose equal to the current U.S. Environmental Protection Agency's reference safe daily limit, on estradiol-induced spine synapse formation in the hippocampus and prefrontal cortex of a nonhuman primate model. Our data indicate that even at this relatively low exposure level, BPA completely abolishes the synaptogenic response to estradiol. Because remodeling of spine synapses may play a critical role in cognition and mood, the ability of BPA to interfere with spine synapse formation has profound implications. This study is the first to demonstrate an adverse effect of BPA on the brain in a nonhuman primate model and further amplifies concerns about the widespread use of BPA in medical equipment, and in food preparation and storage.
Thursday, October 02, 2008
A complete group of sleep characteristics (rapid-eye-movement sleep and slow-wave sleep as well as transition stages and quick spikes) has been found outside of mammals, in zebra finches, a surprising finding because birds lack a neocortex, the part of the mammalian brain thought necessary for such patterns. Low et al. suggest that ancestral characteristics of sleep evolved under selective pressures common to songbirds and mammals. This would fit with Tononi's suggestion that sleep is required for synaptic homeostasis and regenerations (a form of sleep is also observed in fruitflies). Here is their abstract:
A suite of complex electroencephalographic patterns of sleep occurs in mammals. In sleeping zebra finches, we observed slow wave sleep (SWS), rapid eye movement (REM) sleep, an intermediate sleep (IS) stage commonly occurring in, but not limited to, transitions between other stages, and high amplitude transients reminiscent of K-complexes. SWS density decreased whereas REM density increased throughout the night, with late-night characterized by substantially more REM than SWS, and relatively long bouts of REM. Birds share many features of sleep in common with mammals, but this collective suite of characteristics had not been known in any one species outside of mammals. We hypothesize that shared, ancestral characteristics of sleep in amniotes evolved under selective pressures common to songbirds and mammals, resulting in convergent characteristics of sleep.
An interesting study by van Duijvenvoorde et al. compares the utility of positive versus negative strokes during learning in three age groups (8–9, 11–13, and 18–25 year of age). Cognitive control areas are engaged best by positive feedback in the youngest group, and by negative feedback in the oldest. Here is their abstract:
How children learn from positive and negative performance feedback lies at the foundation of successful learning and is therefore of great importance for educational practice. In this study, we used functional magnetic resonance imaging (fMRI) to examine the neural developmental changes related to feedback-based learning when performing a rule search and application task. Behavioral results from three age groups (8–9, 11–13, and 18–25 years of age) demonstrated that, compared with adults, 8- to 9-year-old children performed disproportionally more inaccurately after receiving negative feedback relative to positive feedback. Additionally, imaging data pointed toward a qualitative difference in how children and adults use performance feedback. That is, dorsolateral prefrontal cortex and superior parietal cortex were more active after negative feedback for adults, but after positive feedback for children (8–9 years of age). For 11- to 13-year-olds, these regions did not show differential feedback sensitivity, suggesting that the transition occurs around this age. Pre-supplementary motor area/anterior cingulate cortex, in contrast, was more active after negative feedback in both 11- to 13-year-olds and adults, but not 8- to 9-year-olds. Together, the current data show that cognitive control areas are differentially engaged during feedback-based learning across development. Adults engage these regions after signals of response adjustment (i.e., negative feedback). Young children engage these regions after signals of response continuation (i.e., positive feedback). The neural activation patterns found in 11- to 13-year-olds indicate a transition around this age toward an increased influence of negative feedback on performance adjustment. This is the first developmental fMRI study to compare qualitative changes in brain activation during feedback learning across distinct stages of development.
Wednesday, October 01, 2008
My boyfriend in the early 19980’s was a pharmacy graduate student whose t-shirt read “Drugs are my life.” If I were to wear such a t-shirt now it would read “Hormones and neurotransmitters are my life.” I increasingly feel that all this verbal stuff we do - chattering in person or in the electronic ether, writing blogs, etc. - is a superficial veneer, noise on top of what is really running the show, which is the waxing and waning of hormones and neurotransmitters directed by an “it”, a martian inside us utterly running its own show. These compounds regulate our assertiveness versus passivity , our trust versus mistrust, our anxiety versus calm, our pleasure during antipication and reward. (They function, respectively, in neural systems that use testosterone, oxytocin, adrenaline, and dopamine.). The swings in these systems become less dramatic as we 'mellow' with aging.
Dreher et al. have published an interesting bit of work that deals specifically with the muting of the intensity of the pleasures we feel during anticipation and reward, in their article on “Age-related changes in midbrain dopaminergic regulation of the human reward system.” Their data show what is going on as we experience less excitement at opening a present when we are 60 than when we are 10 years old. There are changes in the brain's production of dopamine, which plays a central role in our reward system, as well as in which parts of the brain respond to it, and by how much they respond. (a recent brief article on dopamine and the reward system of the brain is here.) Here is their abstract, followed by a figure from the paper.
The dopamine system, which plays a crucial role in reward processing, is particularly vulnerable to aging. Significant losses over a normal lifespan have been reported for dopamine receptors and transporters, but very little is known about the neurofunctional consequences of this age-related dopaminergic decline. In animals, a substantial body of data indicates that dopamine activity in the midbrain is tightly associated with reward processing. In humans, although indirect evidence from pharmacological and clinical studies also supports such an association, there has been no direct demonstration of a link between midbrain dopamine and reward-related neural response. Moreover, there are no in vivo data for alterations in this relationship in older humans. Here, by using 6-[18F]FluoroDOPA (FDOPA) positron emission tomography (PET) and event-related 3T functional magnetic resonance imaging (fMRI) in the same subjects, we directly demonstrate a link between midbrain dopamine synthesis and reward-related prefrontal activity in humans, show that healthy aging induces functional alterations in the reward system, and identify an age-related change in the direction of the relationship (from a positive to a negative correlation) between midbrain dopamine synthesis and prefrontal activity. These results indicate an age-dependent dopaminergic tuning mechanism for cortical reward processing and provide system-level information about alteration of a key neural circuit in healthy aging. Taken together, our findings provide an important characterization of the interactions between midbrain dopamine function and the reward system in healthy young humans and older subjects, and identify the changes in this regulatory circuit that accompany aging.
Legend (click on figure to enlarge). Statistical t maps of the within-groups effects in the different phases of the reward paradigm. (A) (Left) Main effect of anticipating reward in young subjects during the delay period, showing activation in the left intraparietal cortex, ventral striatum, caudate nucleus, and anterior cingulate cortex. (Right) Main effect of anticipating reward in older subjects during the delay period, showing activation in the left intraparietal cortex only. The glass brain and the coronal slice indicate that no ventral striatum activity was observed in older subjects. (B) (Left) Main effect of reward receipt in young subjects at the time of the rewarded outcome showing activation in a large bilateral prefronto-parietal network. (Right) Main effect of reward receipt in older subjects at the time of the rewarded outcome showing bilateral prefronto-parietal activation.