Sexual orientation - basis in brain structure and function

Swaab offers a useful brief review of this topic (PDF here) with a complete list of references.

Genetics of political behaviors - molecular level

I wanted to bring into a separate post the comment by James Fowler on the post below mentioning his work. "We do have some papers that go to the molecular level, associating drd2, drd4, maoa, and 5htt with various political behaviors. One of these papers has just been published in Journal of Politics, and all of these papers are all available at my website
http://jhfowler.ucsd.edu."

Your nose, and your bored brain...

From today's Science NYTimes: An article by Natalie Angier on the emotional clout of smells and the curious fact that smell cues most frequently evoke thoughts of early childhood, under the age of 10 (this certainly has been my experience.) Also, an article by Benedict Carey on the creative aspects of boredome.

A new perspective on the genetic basis of brain diseases

An article by Nicholas Wade notes the emergence of a new view on the genetic basis of brain diseases like schizophrenia (see also article by Sands in Nature). There has been a presumption that we looked hard enough, we would find an ensemble of genes whose mutations typically correlated with a disease. The search for common variants in schizophrenia has largely drawn a blank, suggesting that natural selection has done its job in keeping them at bay (after all, reproductive success is compromised in schizophrenics). A view is emerging that the genetic component of the disease may be due to a large number of variants, each of which is very rare (mainly deletions of DNA segments), rather than to a handful of common variants. According to this new idea, schizophrenia continues to appear because it is driven by a spate of new mutations that occur all the time in the population. The new landscape might complicate development of genetic diagnostics for schizophrenia, but not necessarily of therapies based on understanding the underlying mechanisms of the disease.

Gender differences in math performance...

... don't exist for children in grades 2 to 11, according according to a massive statistical analysis carried out by Hyde et al. on data provided through school reporting on the No Child Left Behind federal program (PDF here) - although there is slightly more male variability in scores.

The theologians, the neurologists, and God

Here is the PDF of a review by Alasdair Coles in a recent issue of Brain of a series of recent books that evaluate contributions of neurobiology to the understanding of the relationships between brain, psyche and God. He reviews the history of such efforts starting with Pascal, William James, and others.

Mendelssohn, conclusion

Here is the posting of the final piece done at the house concert at Twin Valley on 6/29/08 the final movement, allegro appasionata, of Mendelssohn's 2nd piano trio. A notable feature of this finale is its inclusion of the melody of a chorale taken from the sixteenth-century Genevan psalter ''Vor deinen Thron tret ich hiermit.'

Lifespan Mental Activity Predicts Diminished Rate of Hippocampal Atrophy

Valenzuela et al. offer further confirmation of the 'use it or lose it' perspective by showing that lifetime mental activity correlates with a diminished rate of hippocampal atrophy with aging. They suggest that neuroprotection in medial temporal lobe may be one mechanism underlying the link between mental activity and lower rates of dementia observed in population-based studies.

We learn abstract categories unconsciously.

Brady and Oliva report interesting experiments in Psychological Science. Below I pass on their abstract, and also their presentation of the first experiment mentioned:

Recent work has shown that observers can parse streams of syllables, tones, or visual shapes and learn statistical regularities in them without conscious intent (e.g., learn that A is always followed by B). Here, we demonstrate that these statistical-learning mechanisms can operate at an abstract, conceptual level. In Experiments 1 and 2, observers incidentally learned which semantic categories of natural scenes covaried (e.g., kitchen scenes were always followed by forest scenes). Stimuli: In Experiments 3 and 4, category learning with images of scenes transferred to words that represented the categories. In each experiment, the category of the scenes was irrelevant to the task. Together, these results suggest that statistical-learning mechanisms can operate at a categorical level, enabling generalization of learned regularities using existing conceptual knowledge. Such mechanisms may guide learning in domains as disparate as the acquisition of causal knowledge and the development of cognitive maps from environmental exploration.

From their description of the first experiment:

Stimuli: Twelve scene categories were used (see figure): bathroom, bedroom, bridge, building, coast, field, forest, kitchen, living room, mountain, street, and waterfall.


Each category contained 120 different full-color images. For each observer, 1 picture was drawn from each of the 12 categories at random, resulting in a set of 12 different images...Each of the 12 selected images was randomly assigned a position in one of four triplets (e.g., ABC)—sequences of three images that always appeared in the same order. Then a sequence of images was generated by randomly interleaving 75 repetitions of each triplet, with the constraints that the same triplet could never appear twice in a row and the same set of two triplets could never appear twice in a row (e.g., ABCGHIABCGHI was disallowed). In addition, 100 repeat images were inserted into the stream such that sometimes either the first or third image in a triplet repeated immediately (e.g., ABCCGHI or ABCGGHI). Allowing only the first or third image in a triplet to repeat served to keep the triplet structure intact, yet prevented the repeat images from being informative for delineating triplets from one another.

Procedure: Observers watched a 20-min sequence of 1,000 images, presented one at a time for 300 ms each with a 700-ms interstimulus interval (ISI). During this sequence, the task was to detect back-to-back repeats of the same image and to indicate repeats as quickly as possible by hitting the space bar. This cover task was intended to help prevent observers from becoming explicitly aware of the structure in the stream (Turk-Browne et al., 2005), and also avoided having observers simply view the stream passively (which would make it unclear what they were processing). Note that they were never informed that there was any structure in the stream of images...Following this study period, observers were asked if they had recognized any structure in the stream and then were given a surprise forced-choice familiarity test. On each test trial, observers viewed two 3-image test sequences, presented sequentially at the center of the screen with the same ISI as during the study phase and segmented from each other by an additional 1,000-ms pause. One of these test sequences was always a triplet of images that had been seen in the stream (e.g., ABC), and another was a foil constructed from images from three different triplets (e.g., AEI). After the presentation of the two test sequences, observers were told to press either the "1" or the "2" key to indicate whether the first or second test sequence seemed more familiar from the initial study period. Each of the four triplets was tested eight times, paired twice with each of four different foil sequences (AEI, DHL, GKC, JBF), for a total of 32 test trials. Observers' ability to discriminate triplet sequences from foil sequences was used as a measure of statistical learning.

Results and Discussion: All 10 of the observers completed the repeat-detection task during the study period with few errors, detecting an average of 91% of the repetitions (SD= 5%) and committing between one and five false alarms. These results demonstrate that observers were attending to the sequence of images. However, when asked, no observers reported explicitly noticing that the study stream had any structure.1 Nonetheless, performance on the familiarity test indicated very robust statistical learning, with triplets being successfully discriminated from foils (86.6% of the test sequences chosen were triplets, and 13.4% were foils), t(9) = 8.72, p= .00001.

These results extend previous demonstrations of visual statistical learning in two ways. First, they demonstrate visual statistical learning for scene stimuli, which are more complicated and information rich than the stimuli for which statistical learning has been demonstrated previously. Second, choosing the correct triplets at test in this experiment required not just forming episodic associations between the correct pictures, but also overcoming prior knowledge about how the scenes represented are associated in the world (e.g., bridges are rarely associated with living rooms).

In this experiment, learning likely occurred at the image level, because identical stimuli were repeated throughout the learning and test phases (and statistical learning has been previously demonstrated for shape and color.

To examine the role of category-level semantics in statistical learning, the authors then moved on to experiments in which the same string of images was never presented twice, but a pattern occurred at the categorical level.

Would I pull that switch?

I recommend this NYTimes piece by Benedict Carey on recent experiments that give more nuance to the classic Stanley Milgram obedience studies of the early 1960s,

...that together form one of the darkest mirrors the field has held up to the human face. In a series of about 20 experiments, hundreds of decent, well-intentioned people agreed to deliver what appeared to be increasingly painful electric shocks to another person, as part of what they thought was a learning experiment. The “learner” was in fact an actor, usually seated out of sight in an adjacent room, pretending to be zapped.

The more recent work looks at conditions under which which participants were most likely to disobey the experimenter and quit delivering shocks. The participants' perception of the human rights of the learner as well as whether they felt themselves or the experiments actually responsible for delivering the shocks influenced the threshold beyond which they would no longer obey the experimenter.

Your genes and your politics.

Here are some clips from a piece by Constance Holden reporting on presentations at the recent annual Behavior Genetics Association meeting.

Numerous studies over the past 2 decades...have indicated that genes have a significant influence over whether you're "liberal" or "conservative" on various political and social issues. Some heritability estimates have been as high as 50%. That's roughly the heritability found for many personality traits such as "extraversion" or "agreeableness," and it implies that, in a given population, about half of the variation in a particular trait is attributable to genetic differences.

Now James Fowler, UCSD, and grad student Christopher Dawes say they've produced fresh evidence that DNA also has a hand in the intensity of someone's partisan attachment and even in whether someone bothers to vote...they did that by crunching data from twin registries and the government's long-running National Longitudinal Study of Adolescent Health (NLSAH)...they matched data on voting by 396 Los Angeles-area twins, including identical (who share 100% of their genes) and fraternal (who average 50% genetic overlap) twins, obtained from Los Angeles voter-turnout records. All twins were same-sex pairs to avoid confounding results with sex differences. The researchers corrected for environmental factors such as whether more of the identical than fraternal twins were living together, which might inflate their degree of similarity. They concluded that the correlation for voting was much higher between pairs of identical (.71) than fraternal (.50) twins. From this they estimated the heritability of voting behavior--that is, whether people eligible to vote actually do so--at 53%, suggesting that at least half the individual variation can be traced to genetic influences. They found an even higher heritability--72%--when they replicated the study with data on 806 twins from NLSAH, they reported in the May issue of the American Political Science Review.

Several groups are now trying to correlate personality data with DNA markers from studies such as NLSAH, which contains DNA as well as behavioral data from many subjects, in hope of identifying specific genes that feed into underlying traits, such as "desire for cooperation," that Fowler, for one, believes have been selected for throughout human evolution. Studies so far have focused on the same genes that are of interest in psychiatric genetics--in particular those involved with neurotransmitters such as dopamine and serotonin that are known to be important in regulating higher brain activities.

We are talking here about the fact that genetics are important, not really going after a complex behavior like political leanings at the molecular level. What is important is that:

social scientists are plunging into biological and evolutionary issues. At least some are starting to acknowledge that humans are genetically unique individuals and not just cloned pawns of their environment. And that suggests that prophets and pundits, however prescient, are probably never going to get much better at predictions than they are now.

A Twin Valley collage

A few pics I made last Saturday in the yard of our Twin Valley home in Middleton, WI (click to enlarge).

Moral Hypocrisy

John Tierney has a nice piece in the NYTimes on studies that probe moral flip-flops of the sort evidenced in the current presidential campaign. Does the hypocrite really believe in his heart what he is saying? Clips:

In voting against the Bush tax cut in 2001, Senator John McCain said he “cannot in good conscience support a tax cut in which so many of the benefits go to the most fortunate.” Today he campaigns in favor of extending that same tax cut beyond its expiration date...Senator Barack Obama last year called himself a “longtime advocate” of public financing of election campaigns. This month, he reiterated his “support” for such financing while becoming the first major party presidential nominee ever to reject it for his own campaign...Do you think either of these men is a hypocrite?

Moral hypocrisy allows us to gain the social benefits of appearing virtuous without incurring the personal costs of virtuous behavior. If you can deceive even yourself into believing that you’re acting for the common good, you’ll have more energy and confidence to further your own interests — and your self-halo can persuade others to help you along.

But as useful as hypocrisy can be, it’s apparently not quite as basic as the human instinct to do unto others as you would have them do unto you. Your mind can justify double standards, it seems, but in your heart you know you’re wrong.

The Curious Parallel of Language and Species Evolution

An article in PLoS Biology with the title of this post with worth a look. It describes recent work that has it origins in Charles Darwin's passage in The Descent of Man: “The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously parallel.”

If I'm Not Hot, Are You Hot or Not?

Here is a quirky piece. Check out the website indicated...

Prior research has established that people's own physical attractiveness affects their selection of romantic partners. This article provides further support for this effect and also examines a different, yet related, question: When less attractive people accept less attractive dates, do they persuade themselves that the people they choose to date are more physically attractive than others perceive them to be? Our analysis of data from the popular Web site http://HOTorNOT.com suggests that this is not the case: Less attractive people do not delude themselves into thinking that their dates are more physically attractive than others perceive them to be. Furthermore, the results also show that males, compared with females, are less affected by their own attractiveness when choosing whom to date.

WikiPathways...

I spent much of my training and early research career trying to figure out chemical pathways in cells, specifically the pathways linking light to nerve signals in our eyes. I was thus struck by this article describing evolution in the process of how the biology research community maintains and updates knowledge about complex pathway systems. It discusses WikiPathways.

Nasty, brutish and short - a record lifespan

Just to show you the opposite end of the lifespan spectrum - perhaps an antidote to our obsessing over whether we might expand human lifespan from 85 to, say, 105 - here is a curious note from the July 3 Nature on the shortest known vertebrate lifespan: three months.

The Madagascan chameleon Furcifer labordi has an annual life cycle, and spends most of its short life in the egg...Kristopher Karsten of Oklahoma State University in Stillwater and his colleagues monitored individuals from the time of hatching until death during several cycles. They found that they hatch in November; grow at astonishing rates; reach maturity by January; battle fiercely over mates, breed and lay their eggs by February; and then promptly drop dead. For the next nine months, the entire species is represented by eggs...This is the shortest lifespan ever recorded for a four-legged vertebrate animal.

Brain correlates of insight - the Eureka! moment

Jonah Lehrer, in the July 28 issue of The New Yorker, offers an article titled "The Eureka Hunt." Here is the abstract and the PDF is here (thanks to mindblog reader Gregory for the link):

Why do good ideas come to us when they do? On August 5, 1949, a firefighter named Wag Dodge survived an out-of-control fire in the Mann Gulch River Valley, in Montana. In a moment of desperate insight, he devised an escape plan by igniting the ground in front of him and laying down on the smoldering embers, inhaling the thin layer of oxygen clinging to the ground. There is something inherently mysterious about moments of insight. Dodge couldn’t explain where his idea came from. Stories like Dodge’s share a few essential features, which psychologists and neuroscientists use to define “the insight experience.” Mark Jung-Beeman, a cognitive neuroscientist at Northwestern University, has spent the past fifteen years trying to figure out what happens inside the brain when people have an insight. Jung-Beeman became interested in the nature of insight in the early nineteen-nineties, while researching the right hemisphere of the brain. Mentions Jonathan Schooler. Jung-Beeman decided to compare word puzzles—or Compound Remote Associate Problems (C.R.A.)—solved in moments of insight with those solved by methodical testing. He teamed up with John Kounios, a psychologist at Drexler University, and they combined fMRI and EEG (electroencephalography) testing to scan people’s brains while they solved the puzzles. The resulting study, published in 2004, found that people who solved puzzles with insight activated a specific subset of cortical areas. Although the answer seemed to appear out of nowhere, the mind was carefully preparing itself for the breakthrough. The suddenness of the insight is preceded by a burst of brain activity. Thirty milliseconds before the answer appears, the EEG registers a spike of gamma rhythm. A small fold of tissue on the surface of the right hemisphere, the anterior superior temporal gyrus (aSTG), becomes unusually active in the second before the insight. Once the brain is sufficiently focused on the problem, the cortex needs to relax, to seek out the more remote association in the right hemisphere that will provide the insight. As Kounios sees it, the insight process is an act of cognitive deliberation transformed by accidental, serendipitous connections. Mentions Joydeep Bhattacharya and Henri Poincaré. The brain area responsible for recognizing insight is the prefrontal cortex. Earl Miller, a neuroscientist at M.I.T., spent five years studying the prefrontal cortex. He was eventually able to show that it wasn’t simply an aggregator of information, but rather it was more like a conductor, waving its baton and directing the players. In 2001, Miller and Princeton neuroscientist Jonathan Cohen published an influential paper laying out their theory of how the prefrontal cortex controls the rest of the brain. It remains unclear how simple cells recognize what the conscious mind cannot. An insight is just a fleeting glimpse of the brain’s huge store of unknown knowledge.

Mendelssohn, continued

Here is the weekly posting of an portion of the house concert at Twin Valley on 6/29/08 the Andante expressivo from Mendelssohn's 2nd piano trio.

Resveratrol, anti-aging, continued...

After getting a comment about the merits of different resveratrol sources from a blog reader in response post just below , I clicked around and found this link that leads on to an instructional video, discussion of preparations, price comparisons, etc. Numerous vendors for this stuff are appearing, like a cloud of snake-oil salesmen, and one I find particularly suspect is the slick Biotivia outfit, which doesn't even state the resveratrol content of their wondrous products.