Effects of oxytocin in humans - a critical review

Over the past several years MindBlog has posted examples from the outpouring of work on the "trust hormone" oxytocin. Trends in Cognitive Science offers open access to this more critical and balanced review by Bartz et al. Their abstract:

Building on animal research, the past decade has witnessed a surge of interest in the effects of oxytocin on social cognition and prosocial behavior in humans. This work has generated considerable excitement about identifying the neurochemical underpinnings of sociality in humans, and discovering compounds to treat social functioning deficits. Inspection of the literature, however, reveals that the effects of oxytocin in the social domain are often weak and/or inconsistent. We propose that this literature can be informed by an interactionist approach in which the effects of oxytocin are constrained by features of situations and/or individuals. We show how this approach can improve understanding of extant research, suggest novel mechanisms through which oxytocin might operate, and refine predictions about oxytocin pharmacotherapy.

By the way, the same issue of Trends in Cognitive Science has a brief note by van Honk et al. on testosterone as a social hormone, also noting the complexity of hormone-behavior relationships (PDF here).

Macho mice make manly melodies.

Susan Reardon points to work by work of Pasch et al at U of F at Gainesville, who compared the songs of castrated male mice (singing mice from Costa Rica) with males having a male hormone implant. Females were attracted to speakers playing recordings of the songs of hormonally encanced males. (audio file here, video file in links above).

Boredom - a Lively History

Peter Toohey's book with the title of this post is reviewed by Anthony Gottlieb in the NYTimes:

In Oscar Wilde’s play “A Woman of No Importance,” Lord Illingworth says of society: “To be in it is merely a bore. But to be out of it simply a tragedy.” To be a bore oneself is the ultimate failing and makes one the target for a quintessentially English put-down. “Even the grave yawns for him,” the actor and theater manager Sir Herbert Beerbohm Tree once said of an earnest writer. ...it was (and still is) regarded in some quarters as stylish and rather aristocratic to suffer from boredom, so the English ought really to thank their bores for providing them with the occasion to display wit and appear grand.

Toohey...suggests that the unpleasant feeling of simple boredom developed as a warning signal to steer us away from social situations that are “confined, predictable, too samey for one’s sanity.” In other words, it is a useful aversion: the discomfort of boredom is a blessing in disguise...a colleague of his once argued that there isn’t really any such thing as boredom, just a blurring together of a constellation of feelings and moods — frustration, surfeit, apathy and the like. Toohey rejects this idea, and perhaps there is indeed little harm in keeping the word, provided that one is vigilantly aware of the loose, subjective and confusing ways in which it is often used. When the actor George Sanders — the archetypal cad, at least on-screen, and in the title of his autobiography — committed suicide in a Spanish hotel in 1972, he left a note that began: “Dear World, I am leaving because I am bored.” It is worth noting that he was ill, lonely and had sold his beloved house on Majorca. Was boredom really what his death was about? When a man says he is bored — as Oscar Wilde never quite got round to saying — it sometimes means that he cannot be bothered to tell you what really ails him.

Collectivism promotes bribery

From Mazar and Aggarwal:

Why are there national differences in the propensity to bribe? To investigate this question, we conducted a correlational study with cross-national data and a laboratory experiment. We found a significant effect of the degree of collectivism versus individualism present in a national culture on the propensity to offer bribes to international business partners. Furthermore, the effect was mediated by individuals’ sense of responsibility for their actions. Together, these results suggest that collectivism promotes bribery through lower perceived responsibility for one’s actions.

later note: I forgot to put the link to this article, it's now added.

Diversity is Universal

Here is an interesting little nugget from Joan Chiao:

At every level in the vast and dynamic world of living things lies diversity. From biomes to biomarkers, the complex array of solutions to the most basic problems regarding survival in a given environment afforded to us by nature is riveting. In the world of humans alone, diversity is apparent in the genome, in the brain and in our behavior.

The mark of multiple populations lies in the fabric of our DNA. The signature of selfhood in the brain holds dual frames, one for thinking about one's self as absolute, the other in context of others. From this biological diversity in humans arises cultural diversity directly observable in nearly every aspect of how people think, feel and behavior. From classrooms to conventions across continents, the range and scope of human activities is stunning.

Recent centuries have seen the scientific debate regarding the nature of human nature cast as a dichotomy between diversity on the one hand and universalism on the other. Yet a seemingly paradoxical, but tractable, scientific concept that may enhance our cognitive toolkit over time is the simple notion that diversity is universal.

The sunny side of smut.

Coming across an article with the same title as this post gave me an immediate flashback to my days at Harvard, when as a graduate student and resident tutor in Winthrop House I would invite down various campus notables to have dinner in the dining hall at a table with my students (coats and ties were still required then), after which we retired to the common room for a chat over sherry (sigh....the good old days). The guest I'm remembering was the famous psychologist B.F. Skinner, whose immediate response, when he was asked how he managed to remain so vital at his advanced age, was "I read pornography." Here are a few clips from the article in the Scientific American on this topics by Moyer:

...Now pornography is just one Google search away, and much of it is free. Age restrictions have become meaningless, too, with the advent of social media—one teenager in five has sent or posted naked pictures of themselves online...Certainly pornography addiction or overconsumption seems to cause relationship problems...But what about the more casual exposure typical of most porn users?...“There’s absolutely no evidence that pornography does anything negative,” says Milton Diamond​, director of the Pacific Center for Sex and Society at the University of Hawaii at Manoa. “It’s a moral issue, not a factual issue.”...Perhaps the most serious accusation against pornography is that it incites sexual aggression. But not only do rape statistics suggest otherwise, some experts believe the consumption of pornography may actually reduce the desire to rape by offering a safe, private outlet for deviant sexual desires...as access to pornography grew in once restrictive Japan, China and Denmark in the past 40 years, rape statistics plummeted. Within the U.S., the states with the least Internet access between 1980 and 2000—and therefore the least access to Internet pornography—experienced a 53 percent increase in rape incidence, whereas the states with the most access experienced a 27 percent drop in the number of reported rapes .

It is important to note that these associations are just that—associations. They do not prove that pornography is the cause of the observed crime reductions. Nevertheless, the trends just don’t fit with the theory that rape and sexual assault are in part influenced by pornography...patients requesting treatment in clinics for sex offenders commonly say that pornography helps them keep their abnormal sexuality within the confines of their imagination. Pornography seems to be protective...perhaps because exposure correlates with lower levels of sexual repression, a potential rape risk factor.

MindBlog retrospective: A new description of our inner lives.

This is another of my old posts that emerged from the retrospective scan of this blog that I did recently, another interesting perspective I don't want to loose touch with. It drew a number of comments, and a second post several months later discussed them. Here is a repeat of the original post:

I rarely mention my internal experience and sensations on this blog - first, because I have viewed readers as "wanting the beef," objective stuff on how minds work. Second and more important, because my experience of noting the flow of my brain products as emotion laced chunks of sensing/cognition/action - knowing the names of the neurotransmitters and hormones acting during desire, arousal, calming, or affiliation - strikes me as a process which would feel quite alien to most people. Still, if we are materialists who believe that someday we will understand how the brain-body generates our consciousness and sense of a self, we will be able to think in terms like the following (a quote taken from Larissa MacFarquhar's profile of Paul and Patricia Churchland in the Feb. 12 New Yorker Magazine):

"...he and Pat like to speculate about a day when whole chunks of English, especially the bits that consitute folk psychology, are replaced by scientific words that call a thing by its proper name rather than some outworn metaphor... as people learn to speak differently they will learn to experience differently, and sooner or later even their most private introspections will be affected. Already Paul feels pain differently than he used to: when he cut himself shaving now he fells not "pain" but something more complicated - first the sharp, superficial A-delta-fibre pain, and then a couple of seconds later, the sickening, deeper feeling of C-fibre pain that lingers. The new words, far from being reductive or dry, have enhanced his sensations, he feels, as an oenophile's complex vocabulary enhances the taste of wine."

"Paul and Pat, realizing that the revolutionary neuroscience they dream of is still in its infancy, are nonetheless already preparing themselve for this future, making the appropriate adjustments in their everyday conversation. One afternoon recently, Paul says, he was home making dinner when Pat burst in the door, having come straight from a frustrating faculty meeting. "She said, 'Paul, don't speak to me, my serotonin levels have hit bottom, my brain is awash in glucocortocoids, my blood vessels are full of adrenaline, and if it weren't for my endogenous opiates I'd have driven the car into a tree on the way home. My dopamine levels need lifting. Pour me a Chardonnay, and I'll be down in a minute.' " Paul and Pat have noticed that it is not just they who talk this way - their students now talk of psychopharmacology as comfortably as of food."

The utility of being vague.

I'm just getting to glance at the last few issue of Psychological Science, and find this gem, "In Praise of Vagueness" by Mishra et al., which they introduce as follows:

People are increasingly surrounded by devices that provide highly precise information. For instance, technologically advanced bathroom scales can now give measurements of weight, body fat, and hydration levels within two and even three decimal places. People can find out exactly how many calories they are eating, how much weight they can lift, and how many steps they walk in a typical day. The overarching belief exemplified by the use of such technologies could be summed up by the phrase, “If I can measure it, I can manage it.” In other words, people seem to believe that precise information increases their likelihood of performing better and meeting personal goals (e.g., improving physical strength or losing weight). People generally prefer precise information over vague information because precise information gives them a greater sense of security and confidence in their ability to predict unknown outcomes in their environment. Despite this preference, we have found that vague information sometimes serves people better than precise information does.

Why might individuals perform better when they receive vague information than when they receive precise information? We posit that vague information allows individuals leeway in interpretation so that they form expectancies in accordance with the outcomes that they desire. Further, we posit that these positive expectancies can give rise to favorable performance-related outcomes.

Their experiments examined the progress of people towards goals when they were given precise versus vague (error range given) feedback on that progress. Perhaps the most striking example was provided in the weight loss experiment whose participants gained, on average, one pound over the course of the experiment after being given precise feedback, those given vague feedback lost nearly four pounds. Here is their abstract:

Is the eternal quest for precise information always worthwhile? Our research suggests that, at times, vagueness has its merits. Previous research has demonstrated that people prefer precise information over vague information because it gives them a sense of security and makes their environments more predictable. However, we show that the fuzzy boundaries afforded by vague information can actually help individuals perform better than can precise information. We document these findings across two laboratory studies and one quasi–field study that involved different performance-related contexts (mental acuity, physical strength, and weight loss). We argue that the malleability of vague information allows people to interpret it in the manner they desire, so that they can generate positive response expectancies and, thereby, perform better. The rigidity of precise information discourages desirable interpretations. Hence, on certain occasions, precise information is not as helpful as vague information in boosting performance.

Inappropriate cravings? Hold a magnet by your head!

Here's an idea for a BioTech startup!...(I'm not serious)...suggested by an article from McClemon et al. titled "Repetitive Transcranial Magnetic Stimulation of the Superior Frontal Gyrus Modulates Craving for Cigarettes."

BACKGROUND:

Previous functional magnetic resonance imaging studies have shown strong correlations between cue-elicited craving for cigarettes and activation of the superior frontal gyrus (SFG). Repetitive transcranial magnetic stimulation (rTMS) offers a noninvasive means to reversibly affect brain cortical activity, which can be applied to testing hypotheses about the causal role of SFG in modulating craving.

METHODS:

Fifteen volunteer smokers were recruited to investigate the effects of rTMS on subjective responses to smoking versus neutral cues and to controlled presentations of cigarette smoke. On different days, participants were exposed to three conditions: 1) high-frequency (10 Hz) rTMS directed at the SFG; 2) low-frequency (1 Hz) rTMS directed at the SFG; and 3) low-frequency (1 Hz) rTMS directed at the motor cortex (control condition).

RESULTS:

Craving ratings in response to smoking versus neutral cues were differentially affected by the 10-Hz versus 1-Hz SFG condition. Craving after smoking cue presentations was elevated in the 10-Hz SFG condition, whereas craving after neutral cue presentations was reduced. Upon smoking in the 10-Hz SFG condition, ratings of immediate craving reduction as well as the intensity of interoceptive airway sensations were also attenuated.

CONCLUSIONS:

These results support the view that the SFG plays a role in modulating craving reactivity; moreover, the results suggest that the SFG plays a role in both excitatory and inhibitory influences on craving, consistent with prior research demonstrating the role of the prefrontal cortex in the elicitation as well as inhibition of drug-seeking behaviors.

By the way, from Wikipedia via google images, here is the superior frontal gyrus:

Watching Humor in the Brain

Bekinschtein et al. look at what may be the brain correlates of "humor as a cognitive cleanup mechanism" mentioned in my June 17 post, at least in the case of jokes that depend on semantic ambiguity resolution:

What makes us laugh? One crucial component of many jokes is the disambiguation of words with multiple meanings. In this functional MRI study of normal participants, the neural mechanisms that underlie our experience of getting a joke that depends on the resolution of semantically ambiguous words were explored. Jokes that contained ambiguous words were compared with sentences that contained ambiguous words but were not funny, as well as to matched verbal jokes that did not depend on semantic ambiguity. The results confirm that both the left inferior temporal gyrus and left inferior frontal gyrus are involved in processing the semantic aspects of language comprehension, while a more widespread network that includes both of these regions and the temporoparietal junction bilaterally is involved in processing humorous verbal jokes when compared with matched nonhumorous material. In addition, hearing jokes was associated with increased activity in a network of subcortical regions, including the amygdala, the ventral striatum, and the midbrain, that have been implicated in experiencing positive reward. Moreover, activity in these regions correlated with the subjective ratings of funniness of the presented material. These results allow a more precise account of how the neural and cognitive processes that are involved in ambiguity resolu

tion contribute to the appreciation of jokes that depend on semantic ambiguity.

Confabulation

Here is an entry from Fiery Cushman on the Edge.org question "What scientific concept would improve everybody's cognitive toolkit?," on how we frequently rationalize our behavior, unaware of unconscious factors that actually guided it. Here are some clips:

We are shockingly ignorant of the causes of our own behavior. The explanations that we provide are sometimes wholly fabricated, and certainly never complete. Yet, that is not how it feels. Instead it feels like we know exactly what we're doing and why. This is confabulation: Guessing at plausible explanations for our behavior, and then regarding those guesses as introspective certainties…The problem is that we get all of our explanations partly right, correctly identifying the conscious and deliberate causes of our behavior. Unfortunately, we mistake "party right" for "completely right", and thereby fail to recognize the equal influence of the unconscious, or to guard against it.

People make harsher moral judgments in foul-smelling rooms, reflecting the role of disgust as a moral emotion. Women are less likely to call their fathers (but equally likely to call their mothers) during the fertile phase of their menstrual cycle, reflecting a means of incest avoidance. Students indicate greater political conservatism when polled near a hand-sanitizing station during a flu epidemic, reflecting the influence of a threatening environment on ideology. They also indicate a closer bond to their mother when holding hot coffee versus iced coffee, reflecting the metaphor of a "warm" relationship.

Automatic behaviors can be remarkably organized, and even goal-driven. For example, research shows that people tend to cheat just as much as they can without realizing that they are cheating. This is a remarkable phenomenon: Part of you is deciding how much to cheat, calibrated at just the level that keeps another part of you from realizing it.

One of the ways that people pull off this trick is with innocent confabulations: When self-grading an exam, students think, "Oh, I was going to circle e, I really knew that answer!" This isn't a lie, any more than it's a lie to say you have always loved your mother (latte in hand), but don't have time to call your dad during this busy time of the month. These are just incomplete explanations, confabulations that reflect our conscious thoughts while ignoring the unconscious ones.

Perhaps you have noticed that people have an easier time sniffing out unseemly motivations for other's behavior than recognizing the same motivations for their own behavior…we jump to the conclusion that others' behaviors reflect their bad motives and poor judgment, attributing conscious choice to behaviors that may have been influenced unconsciously… we assume that our own choices were guided solely by the conscious explanations that we conjure, and reject or ignore the possibility of our own unconscious biases...By understanding confabulation we can begin to remedy both faults.

The importance of our brains’ resting state activity.

Pizoli et al find, in an open access article describing the clinical case of a young boy with epileptic encephalopathy who underwent successful corpus callosotomy surgery for treatment of drop seizures (i.e., separation of connections between the two hemispheres), that resting state brain activity (temporal synchrony across distributed brain regions termed resting-state networks that persists during waking, sleep, and anesthesia) is required for normal brain development and maintenance:

One of the most intriguing recent discoveries concerning brain function is that intrinsic neuronal activity manifests as spontaneous fluctuations of the blood oxygen level–dependent (BOLD) functional MRI signal. These BOLD fluctuations exhibit temporal synchrony within widely distributed brain regions known as resting-state networks. Resting-state networks are present in the waking state, during sleep, and under general anesthesia, suggesting that spontaneous neuronal activity plays a fundamental role in brain function. Despite its ubiquitous presence, the physiological role of correlated, spontaneous neuronal activity remains poorly understood. One hypothesis is that this activity is critical for the development of synaptic connections and maintenance of synaptic homeostasis. We had a unique opportunity to test this hypothesis in a 5-y-old boy with severe epileptic encephalopathy. The child developed marked neurologic dysfunction in association with a seizure disorder, resulting in a 1-y period of behavioral regression and progressive loss of developmental milestones. His EEG showed a markedly abnormal pattern of high-amplitude, disorganized slow activity with frequent generalized and multifocal epileptiform discharges. Resting-state functional connectivity MRI showed reduced BOLD fluctuations and a pervasive lack of normal connectivity. The child underwent successful corpus callosotomy surgery for treatment of drop seizures. Postoperatively, the patient's behavior returned to baseline, and he resumed development of new skills. The waking EEG revealed a normal background, and functional connectivity MRI demonstrated restoration of functional connectivity architecture. These results provide evidence that intrinsic, coherent neuronal signaling may be essential to the development and maintenance of the brain's functional organization.

Pressure to conform - survey of tight and loose cultures.

Gelfand et al. have constructed a metric they term "tightness-looseness" - the extent to which societies impose social norms, and have collected data across 33 large-scale cultures from ~7,000 individuals. Their questionnaire asked people to rate the appropriateness of 12 behaviors (such as eating or crying) in 15 situations (such as being in a bank or at a party). Then, they compared the responses to an array of ecological and historical factors. From Norenzayan's summary:

...Overall, they found that societies exposed to contemporary or historical threats, such as territorial conflict, resource scarcity, or exposure to high levels of pathogens, more strictly regulate social behavior and punish deviance. These societies are also more likely to have evolved institutions that strictly regulate social norms. At the psychological level, individuals in tightly regulated societies report higher levels of self-monitoring, more intolerant attitudes toward outsiders, and paying stricter attention to time. In this multilevel analysis, ecological, historical, institutional, and psychological variables comprise a loosely integrated system that defines a culture.

These findings complement a growing literature that reveals the power of the comparative approach in explaining critically important features of human behavior. For example, research suggests that the substantial variation in religious involvement among nations can be explained, in large part, by perceived levels of security. Religion thrives when existential threats to human security, such as war or natural disaster, are rampant, and declines considerably in societies with high levels of economic development, low income inequality and infant mortality, and greater access to social safety nets.

The Forbidden Fruit Intuition - our inability to cope with what we know about our minds.

I've recently done a scan of old MindBlog posts, and a number of them stand out so strongly for me, that I want to have their ideas repeated, hoping repetition will aid intellectual assimilation. Here then, a post from April 2006 on Thomas Metzinger's brief essay titled "The Forbidden Fruit Intuition", in the initial post I didn't point to his first paragraph,

We all would like to believe that, ultimately, intellectual honesty is not only an expression of, but also good for your mental health. My dangerous question is if one can be intellectually honest about the issue of free will and preserve one's mental health at the same time. Behind this question lies what I call the "Forbidden Fruit Intuition": Is there a set of questions which are dangerous not on grounds of ideology or political correctness, but because the most obvious answers to them could ultimately make our conscious self-models disintegrate? Can one really believe in determinism without going insane?

Here is the original post:

I get frustrated when I try to reconcile what I know from empirical data to be true about my self (see the "I-Illusion" essay on this website) with the common sense feeling of agency and responsibility that we are share.

Our commonsense conceptions of ourselves have co-evolved over hundreds of thousands of years, along with their physiological, homeostatic, neuroendocrine, and limbic emotional correlates. This whole complex (us, that is) can be upset by facing what it can come to know to be true about the impersonal physical processes that actually run our show, finding it impossible to integrate its 'illusory' self image.

Here is a clip, and then its more extended context from the piece by Metzinger on edge.org..his response to the question "What is your dangerous idea." He frames it much better than I can. First the clip:

"I think that the irritation and deep sense of resentment surrounding public debates on the freedom of the will actually has nothing much to do with the actual options on the table. It has to do with the perfectly sensible intuition that our presently obvious answer will not only be emotionally disturbing, but ultimately impossible to integrate into our conscious self-models."

Then the more extended quotation:

"For middle-sized objects at 37° like the human brain and the human body, determinism is obviously true. The next state of the physical universe is always determined by the previous state. And given a certain brain-state plus an environment you could never have acted otherwise. A surprisingly large majority of experts in the free-will debate today accept this obvious fact...."

"Yes, you are a physically determined system. But this is not a big problem, because, under certain conditions, we may still continue to say that you are "free": all that matters is that your actions are caused by the right kinds of brain processes and that they originate in you. A physically determined system can well be sensitive to reasons and to rational arguments, to moral considerations, to questions of value and ethics, as long as all of this is appropriately wired into its brain. You can be rational, and you can be moral, as long as your brain is physically determined in the right way. You like this basic idea: physical determinism is compatible with being a free agent. You endorse a materialist philosophy of freedom as well. An intellectually honest person open to empirical data, you simply believe that something along these lines must be true.

Now you try to feel that it is true. You try to consciously experience the fact that at any given moment of your life, you could not have acted otherwise. You try to experience the fact that even your thoughts, however rational and moral, are predetermined — by something unconscious, by something you can not see. And in doing so, you start fooling around with the conscious self-model Mother Nature evolved for you with so much care and precision over millions of years: You are scratching at the user-surface of your own brain, tweaking the mouse-pointer, introspectively trying to penetrate into the operating system, attempting to make the invisible visible. You are challenging the integrity of your phenomenal self by trying to integrate your new beliefs, the neuroscientific image of man, with your most intimate, inner way of experiencing yourself. How does it feel?

I think that the irritation and deep sense of resentment surrounding public debates on the freedom of the will actually has nothing much to do with the actual options on the table. It has to do with the perfectly sensible intuition that our presently obvious answer will not only be emotionally disturbing, but ultimately impossible to integrate into our conscious self-models.

Or our societies: The robust conscious experience of free will also is a social institution, because the attribution of accountability, responsibility, etc. are the decisive building blocks for modern, open societies. And the currently obvious answer might be interpreted by many as having clearly anti-democratic implications: Making a complex society work implies controlling the behavior of millions of people; if individual human beings can control their own behavior to a much lesser degree than we have thought in the past, if bottom-up doesn't work, then it becomes tempting to control it top-down, by the state. And this is the second way in which enlightenment could devour its own children. Yes, free will truly is a dangerous question, but for different reasons than most people think. "

Clips: Animal Joys - Diet and Weight

There's a fun article in today's NYTimes Science section ("The Joy of a Sun Bath, a Snuggle, a Bite of Pâté") reviewing a new book by animal behaviorist Jonathan Balcombe on "hedonic ethology" titled “The Exultant Ark.”

Also, one of the best articles on diet and weight loss, by Jean Brodie, that I've recently seen.

Our Umwelt

I found the following bit to be an engaging and refreshing reminder, from David Eagleman:

In 1909, the biologist Jakob von Uexküll introduced the concept of the umwelt. He wanted a word to express a simple (but often overlooked) observation: different animals in the same ecosystem pick up on different environmental signals. In the blind and deaf world of the tick, the important signals are temperature and the odor of butyric acid. For the black ghost knifefish, it's electrical fields. For the echolocating bat, it's air-compression waves. The small subset of the world that an animal is able to detect is its umwelt. The bigger reality, whatever that might mean, is called the umgebung.

The interesting part is that each organism presumably assumes its umwelt to be the entire objective reality "out there." Why would any of us stop to think that there is more beyond what we can sense?…it rarely strikes us that things could be different. Similarly, until a child learns in school that honeybees enjoy ultraviolet signals and rattlesnakes employ infrared, it does not strike her that plenty of information is riding on channels to which we have no natural access. From my informal surveys, it is very uncommon knowledge that the part of the electromagnetic spectrum that is visible to us is less than a ten-trillionth of it.

Our brains are tuned to detect a shockingly small fraction of the surrounding reality. Our sensorium is enough to get by in our ecosystem, but is does not approximate the larger picture...I think it would be useful if the concept of the umwelt were embedded in the public lexicon. It neatly captures the idea of limited knowledge, of unobtainable information, and of unimagined possibilities. Consider the criticisms of policy, the assertions of dogma, the declarations of fact that you hear every day — and just imagine if all of these could be infused with the proper intellectual humility that comes from appreciating the amount unseen.

Peer pressure influences our memories

Fascinating observations from Edelson et al., who examine how our accurate initial memories of an event can be be changed by hearing different accounts from others. They find that activity in the hippocampus and amygdala brain regions involved in memory can vary, depending on how our memory has been shaped by interacting with others. Here is their abstract:

Human memory is strikingly susceptible to social influences, yet we know little about the underlying mechanisms. We examined how socially induced memory errors are generated in the brain by studying the memory of individuals exposed to recollections of others. Participants exhibited a strong tendency to conform to erroneous recollections of the group, producing both long-lasting and temporary errors, even when their initial memory was strong and accurate. Functional brain imaging revealed that social influence modified the neuronal representation of memory. Specifically, a particular brain signature of enhanced amygdala activity and enhanced amygdala-hippocampus connectivity predicted long-lasting but not temporary memory alterations. Our findings reveal how social manipulation can alter memory and extend the known functions of the amygdala to encompass socially mediated memory distortions.

Stress and the City

The number of the world's people living in cities has increased from 30% to 50% since 1950, and by 2050 is projected to be ~70%. Many experiments, done on insects, rodents, primates, and humans, have shown that extremes of either social isolation or crowding can have harmful effects. Lederbogen et al. have now used functional magnetic resonance imaging to examine specific human brain structures that are affected by urban living, comparing people living in rural areas, towns with more than 10,000 residents, and cities with more than 100,000 residents. They replicated their findings in several separate samples, used two different stress-inducing tasks, and demonstrated that there were no effects of urbanicity on brain activation when participants performed a non-stressful cognitive task. Stress increased participants' heart rate, blood pressure, saliva cortisol, and activity in the amygdala, with city dwellers showing the largest increases. They found that participants' age, education, income, marital and family status, as well as aspects of their health, mood, personality and the amount of social support they had did not significantly influence the effects of urbanicity. Thus they suggest that living in a city environment changes brain response during a social stressor by a distinct, but mysterious, mechanism. Here is the abstract:

More than half of the world’s population now lives in cities, making the creation of a healthy urban environment a major policy priority. Cities have both health risks and benefits1, but mental health is negatively affected: mood and anxiety disorders are more prevalent in city dwellers and the incidence of schizophrenia is strongly increased in people born and raised in cities. Although these findings have been widely attributed to the urban social environment, the neural processes that could mediate such associations are unknown. Here we show, using functional magnetic resonance imaging in three independent experiments, that urban upbringing and city living have dissociable impacts on social evaluative stress processing in humans. Current city living was associated with increased amygdala activity, whereas urban upbringing affected the perigenual anterior cingulate cortex, a key region for regulation of amygdala activity, negative affect and stress. These findings were regionally and behaviourally specific, as no other brain structures were affected and no urbanicity effect was seen during control experiments invoking cognitive processing without stress. Our results identify distinct neural mechanisms for an established environmental risk factor, link the urban environment for the first time to social stress processing, suggest that brain regions differ in vulnerability to this risk factor across the lifespan, and indicate that experimental interrogation of epidemiological associations is a promising strategy in social neuroscience.

http://www.nature.com/nature/journal/v474/n7352/full/474452a.html

http://www.nature.com/nature/journal/v474/n7352/full/nature10190.html

Effects of blue light on our memory, cognition, and circadian thythm

I ran a vision research laboratory for 30 years,  and in the early 1970s found that installing natural spectrum florescent lights (with more blue wavelengths) in my research laboratory enhanced my relaxation and alertness. My graduate students and post-docs reported the same effect.  Following this subject I've done posts on work documenting this effect, and then subsequently finding that blue light is the best stimulus for a visual pathway that lies outside of the classical (red/green/blue) rod and cone photoreceptor cells of our retinas, driven by a the blue sensitive visual pigment melanopsin in some inner (ganglion) cells of the retina. The amygdala, at the core of our emotional brain, receives direct projections from these light sensitive retinal ganglion cells. Activation of this system also causes changes in brain areas related to working memory. An article by Beil now points to recent work noting consequences of the fact that that blue light is especially effective in suppressing the sleep promoting hormone melatonin that regulates our diurnal sleep-wake cycle. To examine the effects of energy-efficient light bulbs and electronic gadgets with LED screens that have greatly increased levels of blue light wavelengths, some researchers at the University of Basel:

...asked 13 men to sit before a computer each evening for two weeks before going to bed. During one week, for five hours every night, the volunteers sat before an old-style fluorescent monitor emitting light composed of several colors from the visible spectrum, though very little blue. Another week, the men sat at screens backlighted by light-emitting diodes, or LEDs. This screen was twice as blue...Melatonin levels in volunteers watching the LED screens took longer to rise at night, compared with when the participants were watching the fluorescent screens, and the deficit persisted throughout the evening...The subjects also scored higher on tests of memory and cognition after exposure to blue light...The finding adds to a series of others suggesting... that exposure to blue light may keep us more awake and alert, partly by suppressing production of melatonin. An LED screen bright enough and big enough could be giving an alert stimulus at a time that will frustrate the body’s ability to go to sleep later.

Watching contextual memories

Our memories from a particular time and place are linked together (recall Proust's Madeleine cookie) and referred to as contextual memory. Benedict Carey points to an elegant study by Manning et al. that has studied 69 neurosurgical patients who were implanted with subdural electrode arrays and depth electrodes during treatment for drug-resistant epilepsy. As electrocorticographic (ECoG) signals were recorded, the patients volunteered to participate in a free recall memory experiment, in which they studied lists of common nouns and then attempted to recall them verbally in any order following a brief delay. Their results suggest that memory is like a streaming video that is bookmarked, both consciously and subconsciously. New memories of even abstract facts are encoded in brain-cell firing sequences that also contains information about what else was happening during and just before the memory was formed. Here is their abstract, followed by a striking figure from the paper:

Psychological theories of memory posit that when people recall a past event, they not only recover the features of the event itself, but also recover information associated with other events that occurred nearby in time. The events surrounding a target event, and the thoughts they evoke, may be considered to represent a context for the target event, helping to distinguish that event from similar events experienced at different times. The ability to reinstate this contextual information during memory search has been considered a hallmark of episodic, or event-based, memory. We sought to determine whether context reinstatement may be observed in electrical signals recorded from the human brain during episodic recall. Analyzing electrocorticographic recordings taken as 69 neurosurgical patients studied and recalled lists of words, we uncovered a neural signature of context reinstatement. Upon recalling a studied item, we found that the recorded patterns of brain activity were not only similar to the patterns observed when the item was studied, but were also similar to the patterns observed during study of neighboring list items, with similarity decreasing reliably with positional distance. The degree to which individual patients displayed this neural signature of context reinstatement was correlated with their tendency to recall neighboring list items successively. These effects were particularly strong in temporal lobe recordings. Our findings show that recalling a past event evokes a neural signature of the temporal context in which the event occurred, thus pointing to a neural basis for episodic memory.

Evidence for context reinstatement in the temporal lobe. (A) Each dot marks the location of a single electrode from our dataset in Montreal Neurological Institute space. We divided our dataset into four regions of interest: temporal lobe (blue, 1,815 electrodes), frontal lobe (red, 1,737 electrodes), parietal lobe (yellow, 512 electrodes), and occipital lobe (green, 138 electrodes).