Disadvantage, self control, and health

A very sobering study from Miller et al:

There are persistent socioeconomic disparities in many aspects of child development in America. Relative to their affluent peers, children of low socioeconomic status (SES) complete fewer years of education, have a higher prevalence of health problems, and are convicted of more criminal offenses. Based on research indicating that low self-control underlies some of these disparities, policymakers have begun incorporating character-skills training into school curricula and social services. However, emerging data suggest that for low-SES youth, self-control may act as a “double-edged sword,” facilitating academic success and psychosocial adjustment, while at the same time undermining physical health. Here, we examine this hypothesis in a five-wave study of 292 African American teenagers from rural Georgia. From ages 17 to 20 y, we assessed SES and self-control annually, along with depressive symptoms, substance use, aggressive behavior, and internalizing problems. At age 22 y, we obtained DNA methylation profiles of subjects’ peripheral blood mononuclear cells. These data were used to measure epigenetic aging, a methylation-derived biomarker reflecting the disparity between biological and chronological aging. Among high-SES youth, better mid-adolescent self-control presaged favorable psychological and methylation outcomes. However, among low-SES youth, self-control had divergent associations with these outcomes. Self-control forecasted lower rates of depressive symptoms, substance use, aggressive behavior, and internalizing problems but faster epigenetic aging. These patterns suggest that for low-SES youth, resilience is a “skin-deep” phenomenon, wherein outward indicators of success can mask emerging problems with health. These findings have conceptual implications for models of resilience, and practical implications for interventions aimed at ameliorating social and racial disparities.

Biased internet search engines might influence election outcomes

Just in case you are not pessimistic enough already about election manipulations that insure our continued governance by the 1% for the 1% , here is more disturbing information from Epstein and Robertson on the effect that biased internet search engines can have.  (And, see Epstein's article in Politico "How Google could influence the next election"):

Significance

We present evidence from five experiments in two countries suggesting the power and robustness of the search engine manipulation effect (SEME). Specifically, we show that (i) biased search rankings can shift the voting preferences of undecided voters by 20% or more, (ii) the shift can be much higher in some demographic groups, and (iii) such rankings can be masked so that people show no awareness of the manipulation. Knowing the proportion of undecided voters in a population who have Internet access, along with the proportion of those voters who can be influenced using SEME, allows one to calculate the win margin below which SEME might be able to determine an election outcome.

Abstract

Internet search rankings have a significant impact on consumer choices, mainly because users trust and choose higher-ranked results more than lower-ranked results. Given the apparent power of search rankings, we asked whether they could be manipulated to alter the preferences of undecided voters in democratic elections. Here we report the results of five relevant double-blind, randomized controlled experiments, using a total of 4,556 undecided voters representing diverse demographic characteristics of the voting populations of the United States and India. The fifth experiment is especially notable in that it was conducted with eligible voters throughout India in the midst of India’s 2014 Lok Sabha elections just before the final votes were cast. The results of these experiments demonstrate that (i) biased search rankings can shift the voting preferences of undecided voters by 20% or more, (ii) the shift can be much higher in some demographic groups, and (iii) search ranking bias can be masked so that people show no awareness of the manipulation. We call this type of influence, which might be applicable to a variety of attitudes and beliefs, the search engine manipulation effect. Given that many elections are won by small margins, our results suggest that a search engine company has the power to influence the results of a substantial number of elections with impunity. The impact of such manipulations would be especially large in countries dominated by a single search engine company.

Introverts prefer mountains.

From Oishi et al.:

In five studies, we tested the link between personality and geography. We found that mountain-lovers were more introverted than ocean-lovers (Study 1). People preferred the ocean over mountains when they wanted to socialize with others, but they preferred the mountains and the ocean equally when they wanted to decompress alone (Study 2). In Study 3, we replicated the introversion–extraversion differences using pictures of mountains and oceans. Furthermore, this difference was explained in part by extraverts’ perception that it would take more work to have fun in the mountains than in the ocean. Extending the first three studies to non-students, we found that residents of mountainous U.S. states were more introverted than residents of flat states (Study 4). In Study 5, we tested the link between introversion and the mountains experimentally by sending participants to a flat, open area or a secluded, wooded area. The terrain did not make people more introverted, but introverts were happier in the secluded area than in the flat/open area, which is consistent with the person–environment fit hypothesis.

Unequal, but happy

I just came across an article in my queue of potential posts by Steven Quantz and Anette Asp that I had put aside, thinking to check whether this was the same Quantz who I vaguely remember reviewing my Biology of Mind book some time ago. I hunted down the review (in Trends in Neuroscience, May 2000) and sure enough, it is the same guy, then and now at Cal Tech, a professor of philosophy who atempts to relate advances in understanding the neuroscience of the brain to the humanities and social sciences, in fields such as neuroethics, neuroaesthetics, and neuroeconomics.

His piece with Asp in the NY Times Sunday Review deals with the same topic as my July 10 post, "Why don't the poor rise up?", and takes another perspective, described in their recent book "Cool"- How the Brain’s Hidden Quest for Cool Drives Our Economy and Shapes Our World.

...inequality is increasingly disorganized. Consumerism has expanded the lifestyles, niches and brands that supply the statuses we seek.

As a result, social status, which was once hierarchical and zero-sum, has become more fragmented, pluralistic and subjective. The relationship between relative income and relative status, which used to be straightforward, has gotten much more complex.

By the 1950s, rapidly rising standards of living across the West, combined with social pressures to conform, all conspired to intensify status competition. The architects of “rebel cool,” like Jack Kerouac and Norman Mailer, responded by rebelling against emulation consumption and the status hierarchy of postwar America. They inverted the dominant social hierarchy, rejecting the values of those at the top and appropriating the values of those who had been marginalized at the bottom.

The pursuit of “the cool,” in our view, fundamentally altered the psychological motivations underlying our consumer choices. In conspicuous consumption, our emulation of higher-ups means we compete directly for status because we want what they have. But rebellious consumption changed the game, by making a product’s worth depend on how it embodied values that rejected a dominant group’s status.

By comparing a PC user to an Orwellian drone while likening a Mac user to a sexy athlete in its iconic “1984” ad, Apple made a fundamental claim about the allure of its products. Today, Apple products are expensive because they’re seen as cool; they’re not cool because they’re expensive (which is still the case for many luxury goods).

Asking people merely to look at products and people they considered “cool” sparks a pattern of brain activation in the medial prefrontal cortex — a part of the brain that is involved in daydreaming, planning and ruminating — similar to what happens when people receive praise. Our brain’s medial prefrontal cortex, in short, tracks our social esteem.

A new generation of ethnographers has discovered an explosion of consumer lifestyles and product diversification in recent decades. From evangelical Christian Harley-Davidson owners...to lifestyles organized around musical tastes, from the solidarity of punk rockers to yoga gatherings, from meditation retreats to book clubs, we use products to create and experience community. These communities often represent a consumer micro-culture, a “brand community,” or tribe, with its own values and norms about status.

The proliferation of consumer choice helps explain why today’s Gilded Age hasn’t sparked as much outrage as the last one. Money may not buy happiness in the long run, but consumer choice has gone a long way in keeping most Americans reasonably content, even if they shouldn’t be.

People who eat spicy food live longer.

I pass on this interesting bit of information because I, like my father and grandfather, am addicted to hot sauce containing chili peppers (use it with every breakfast). Their main ingredient is capsaicin, which is known to have antioxidant and anti-inflammatory properties. A huge Chinese study of 485,000 people over an average of more than seven years found consuming spicy food once a day correlated with a 14% reduction in risk of death, and also reduced rates of ischemic heart disease, respiratory diseases and cancers.

Tracking ongoing cognition with fMRI of functional connectivity states.

This work by Gonzalez-Castillo at al. shows how close we are getting to real time monitoring of brain activity associated with different kinds of tasks (in this study, distinguishing functional connectivity distinctive to memory vs. rest, math vs. rest, and video vs. rest.)

Functional connectivity (FC) patterns in functional MRI exhibit dynamic behavior on the scale of seconds, with rich spatiotemporal structure and limited sets of whole-brain, quasi-stable FC configurations (FC states) recurring across time and subjects. Based on previous evidence linking various aspects of cognition to group-level, minute-to-minute FC changes in localized connections, we hypothesized that whole-brain FC states may reflect the global, orchestrated dynamics of cognitive processing on the scale of seconds. To test this hypothesis, subjects were continuously scanned as they engaged in and transitioned between mental states dictated by tasks. FC states computed within windows as short as 22.5 s permitted robust tracking of cognition in single subjects with near perfect accuracy. Accuracy dropped markedly for subjects with the lowest task performance. Spatially restricting FC information decreased accuracy at short time scales, emphasizing the distributed nature of whole-brain FC dynamics, beyond univariate magnitude changes, as valuable markers of cognition.

Anti-aging therapies? Start by quantifying aging in young adults for early intervention.

Belsky et al. show that aging processes can be quantified in people still young enough for prevention of age-related disease, opening a new door for antiaging therapies.

Antiaging therapies show promise in model organism research. Translation to humans is needed to address the challenges of an aging global population. Interventions to slow human aging will need to be applied to still-young individuals. However, most human aging research examines older adults, many with chronic disease. As a result, little is known about aging in young humans. We studied aging in 954 young humans, the Dunedin Study birth cohort, tracking multiple biomarkers across three time points spanning their third and fourth decades of life. We developed and validated two methods by which aging can be measured in young adults, one cross-sectional and one longitudinal. Our longitudinal measure allows quantification of the pace of coordinated physiological deterioration across multiple organ systems (e.g., pulmonary, periodontal, cardiovascular, renal, hepatic, and immune function). We applied these methods to assess biological aging in young humans who had not yet developed age-related diseases. Young individuals of the same chronological age varied in their “biological aging” (declining integrity of multiple organ systems). Already, before midlife, individuals who were aging more rapidly were less physically able, showed cognitive decline and brain aging, self-reported worse health, and looked older. Measured biological aging in young adults can be used to identify causes of aging and evaluate rejuvenation therapies.

Exercise for the aging brain - how much is necessary?

Gretchen Reynolds points to interesting work on exercise and the aging brain by Vidoni et. al. Increasing amounts of aerobic exercise (75, 150, 225 minutes per week of walking) correlated with correspondingly increased cardiorespiratory fitness, but the degree of improvement in thinking skills, compared with non-exercising controls, was the same regardless of the duration of exercise. This suggests that a small dose of exercise may be sufficient to improve many aspects of thinking.

What is fair? It depends on your culture.

Tomasello and collaborators note interesting cultural differences in distributive justice:

Distributing the spoils of a joint enterprise on the basis of work contribution or relative productivity seems natural to the modern Western mind. But such notions of merit-based distributive justice may be culturally constructed norms that vary with the social and economic structure of a group. In the present research, we showed that children from three different cultures have very different ideas about distributive justice. Whereas children from a modern Western society distributed the spoils of a joint enterprise precisely in proportion to productivity, children from a gerontocratic pastoralist society in Africa did not take merit into account at all. Children from a partially hunter-gatherer, egalitarian African culture distributed the spoils more equally than did the other two cultures, with merit playing only a limited role. This pattern of results suggests that some basic notions of distributive justice are not universal intuitions of the human species but rather culturally constructed behavioral norms.

Knowing the internal states of ourselves and of others.

We frequently can infer the emotional state of someone from the style of their movement, distinguishing, for example, when they hand us something rudely versus gently. The time, space, force, trajectory, and direction of the handing movement differ, reflecting what Rizzolattia and colleagues call different 'vitality forms.' They find that vitality forms in the three different tasks of action observation, imagination, and self execution correlate with consistent activation of the dorsocentral sector of the insula:

Vitality form is a term that describes the style with which motor actions are performed (e.g., rude, gentle, etc.). They represent one characterizing element of conscious and unconscious bodily communication. Despite their importance in interpersonal behavior, vitality forms have been, until now, virtually neglected in neuroscience. Here, using the functional MRI (fMRI) technique, we investigated the neural correlates of vitality forms in three different tasks: action observation, imagination, and execution. Conjunction analysis showed that, in all three tasks, there is a common, consistent activation of the dorsocentral sector of the insula. In addition, a common activation of the parietofrontal network, typically active during arm movements production, planning, and observation, was also found. We conclude that the dorsocentral part of the insula is a key element of the system that modulates the cortical motor activity, allowing individuals to express their internal states through action vitality forms. Recent monkey anatomical data show that the dorsocentral sector of the insula is, indeed, connected with the cortical circuit involved in the control of arm movements.

Overclaiming - the illusion of knowledge

Atir et al. probe how our inflated perception of our expertise can lead us to make claims of impossible knowledge. Their edited abstract:

People overestimate their knowledge, at times claiming knowledge of concepts, events, and people that do not exist and cannot be known, a phenomenon called overclaiming. What underlies assertions of such impossible knowledge? We found that people overclaim to the extent that they perceive their personal expertise favorably. A first set of studies showed that self-perceived financial knowledge positively predicts claiming knowledge of nonexistent financial concepts (invented by the researchers: pre-rated stocks, fixed-rate deduction, annualized credit), independent of actual knowledge. A second study demonstrated that self-perceived knowledge within specific domains (e.g., biology) is associated specifically with overclaiming within those domains (taking the fictitious terms meta-toxins, bio-sexual, and retroplex to be real). In another study, warning participants that some of the concepts they saw were fictitious did not reduce the relationship between self-perceived knowledge and overclaiming, which suggests that this relationship is not driven by impression management. Finally, boosting self-perceived expertise in geography (by having participants take an easy versus difficult geography quiz) prompted assertions of familiarity with nonexistent places, which supports a causal role for self-perceived expertise in claiming impossible knowledge.

The authors note this line by American historial Daniel Boorstin (1914-2004): "The menace to understanding is not so much ignorance as the illusion of knowledge."

Habitual exercise correlates with lower distractibility.

Yet another demonstration of the salutary effects of long term exercise on mental function:

Aging is associated with compromised executive control functions. Several lines of evidence point to beneficial effects of physical activity on cognition which indicate that regular physical activity may counteract the age-related decline of some executive functions. Here, we investigate the effects of lifelong physical activity (about 50 years) on interference processing in two matched groups of 20 physically high active and 20 low active healthy older men using event-related potentials (ERPs). In a low interference block of the Stroop task, participants had to indicate the meaning of color-words, while color was either compatible or incompatible with the meaning. In the high interference block, participants were asked to respond according to the ink color of the word and to ignore its meaning. Physically active seniors showed faster reaction times, lower individual variability in reaction times, and higher accuracy compared to low active seniors, particularly in the high interference block. This result was confirmed in the classic paper-and-pencil version of the Stroop task showing higher interference score in the low active than high active individuals. ERPs revealed a shorter latency of the P2 and generally more negative amplitudes of the fronto-central N2 and N450 components in the high active group compared to the low active group. The amount of interference was negatively correlated with objectively measured fitness and self-reported physical activity. The positive effect of physical fitness on interference processing in the behavioral data was related to N2 and N450 amplitudes. Taken together, this suggests that seniors reporting long-term physical activity may exhibit generally enhanced activity in the frontal cortex which enables more efficient interference resolution in the Stroop task.

The benefits of pupil orientation.

This is kinda neat, from the current issue of Science Magazine:

 

Slit-eyed animals have either vertical or horizontal pupils. It is unclear whether one orientation conveys any sort of competitive advantage over the other, and if so, under what circumstances. Banks et al. suggest that the optics of vertical pupil slits generally benefit predators, whereas the optics of horizontal slits benefit prey. Vertical slits are better for estimating object distance and distances along the ground—perfect for a predator stalking its prey. In contrast, horizontal slits are better for seeing objects on the horizon—ideal for prey seeing an approaching predator and deciding which way to flee.

Are Chatbots destined to become our most sympathetic listeners?

Markoff and Mozur do a fascinating piece in the NYTimes describing how millions of young Chinese use a smartphone program as their intimate companion.

Xiaoice (pronounced Shao-ice) can chat with so many people for hours on end because she is not real. She is a chatbot, a program introduced last year by Microsoft that has become something of a hit in China. It is also making the 2013 film “Her,” in which the actor Joaquin Phoenix plays a character who falls in love with a computer operating system, seem less like science fiction.

The program remembers details from previous exchanges with users, such as a breakup with a girlfriend or boyfriend, and asks in later conversations how the user is feeling. Xiaoice is a text-messaging program; the next version will include a Siri-like voice so people can talk with Xiaoice.

Microsoft has been able to give Xiaoice a more compelling personality and sense of “intelligence” by systematically mining the Chinese Internet for human conversations. The company has developed language processing technology that picks out pairs of questions and answers from actual typed conversations. As a result, Xiaoice has a database of responses that are human and current — she is fond of using emojis, too. (Xiaoice translates roughly to “Little Bing,” after the Microsoft search engine.)

The Microsoft App website lists a few simple English language chat bots, with only a few reviews, nothing like the sophisticated A.I. software being used by the Chinese Microsoft program in Beijing.

Benefits of High School Music training.

Maybe my avoiding gym classes in high school by being in the marching band and chorus paid off some brain benefits (in addition to my already being a pianist). This this work from Tierney et al. also suggests that the nationwide savaging of high school music curricula is a really bad idea.:

Fundamental changes in brain structure and function during adolescence are well-characterized, but the extent to which experience modulates adolescent neurodevelopment is not. Musical experience provides an ideal case for examining this question because the influence of music training begun early in life is well-known. We investigated the effects of in-school music training, previously shown to enhance auditory skills, versus another in-school training program that did not focus on development of auditory skills (active control). We tested adolescents on neural responses to sound and language skills before they entered high school (pretraining) and again 3 y later. Here, we show that in-school music training begun in high school prolongs the stability of subcortical sound processing and accelerates maturation of cortical auditory responses. Although phonological processing improved in both the music training and active control groups, the enhancement was greater in adolescents who underwent music training. Thus, music training initiated as late as adolescence can enhance neural processing of sound and confer benefits for language skills. These results establish the potential for experience-driven brain plasticity during adolescence and demonstrate that in-school programs can engender these changes.

Synchronizing brain theta oscillations strengthens our adaptive behavior control.

Reinhart et al. show that synchronizing low-frequency theta (4-8 Hz) EEG oscillations over the medial-frontal cortex with noninvasive direct current electrical stimulation enhances adaptive control of behavior. :

Significance

The ability to exert control over our behavior is fundamental to human cognition, and is impaired in many neuropsychiatric disorders. Here, we show evidence for the neural mechanisms of adaptive control that distinguish healthy people from people who have schizophrenia. We found that the noninvasive electrical stimulation phase aligns low-frequency brain rhythms and enhances functional connectivity. This brain stimulation modulated the temporal structure of low-frequency oscillations and synchrony, improving adaptive control. Moreover, we found that causal changes in the low-frequency oscillations improved behavioral responses to errors and long-range connectivity at the single-trial level. These results implicate theories of executive control and cortical dysconnectivity, and point to the possible development of nonpharmacological treatment alternatives for neuropsychiatric conditions. 

Abstract

Executive control and flexible adjustment of behavior following errors are essential to adaptive functioning. Loss of adaptive control may be a biomarker of a wide range of neuropsychiatric disorders, particularly in the schizophrenia spectrum. Here, we provide support for the view that oscillatory activity in the frontal cortex underlies adaptive adjustments in cognitive processing following errors. Compared with healthy subjects, patients with schizophrenia exhibited low frequency oscillations with abnormal temporal structure and an absence of synchrony over medial-frontal and lateral-prefrontal cortex following errors. To demonstrate that these abnormal oscillations were the origin of the impaired adaptive control in patients with schizophrenia, we applied noninvasive dc electrical stimulation over the medial-frontal cortex. This noninvasive stimulation descrambled the phase of the low-frequency neural oscillations that synchronize activity across cortical regions. Following stimulation, the behavioral index of adaptive control was improved such that patients were indistinguishable from healthy control subjects. These results provide unique causal evidence for theories of executive control and cortical dysconnectivity in schizophrenia.

Another awesome brain video

Science Magazine passes on a video from work reported in Cell Magazine:

New stuff on exercise, brain, and body.

I'll use this post to point readers to several recent interesting articles on physical activity. Hutchinson does a review of work that distinguishes the effect of strength and endurance training versus balance and stability training. The former isn't all that useful without the later, especially in older adults (have you tried standing on one leg with your eyes closed lately?). A German study followed aged adults for 12 months comparing those who did cardiovascular (walking) exercise three times a week, with those who did coordination training. Both groups showed improvement in cognitive functioning, but in different ways. Cardiovascular training was associated with an increased activation of the sensorimotor network, whereas coordination training was associated with increased activation in the visual–spatial network. Mouse studies show that aerobic exercise and strength training trigger brain chemicals that enhance neuron growth and survival, while balance and coordination exercises also recruit higher-level cognitive processes that seem to increase the number of synapses connecting neurons. Work by Kumpulainen et. al. suggests that novelty and unpredictability (as in gymnasts or dancers), rather than repetition (as in endurance athletes), are essential in brain plasticity and engagement.

In another item, Reynolds updates the story on the beneficial effects of intense interval training. Just a few minutes of very intense exercise are much more effective in improving health and cardiovascular fitness than slow and steady repetitive exercise. To try to deal with the problem that most people really don't enjoy zonking themselves out with intense intervals, Bangsbo and collaborators tried a different approach, asking runners to run gently for 30 seconds, then accelerate to a moderate pace for 20 seconds, then sprint as hard as possible for 10 seconds. Repeat five times, rest for a bit, and continue the sequence during a 5-km run. They observed the same beneficial effects on blood pressure and endurance observed with more arduous (several minute) bouts of high intensity training. I tried this 30-20-10 sequence with my favored aerobic exercise, swimming (just counting the intervals to myself made them pass more quickly), and I came out of the routine feeling way more wired than after my usual moderately active swim period.

Brain correlates of the impatience of adolescents.

Teens and young adults show greater impulsivity than children and adults, reflected by increases in emergency room visits, accidents from drug or alcohol use, and increased mortality risk. van den Bos et al. relate this to developmental changes in the structural and functional connectivity of different frontostriatal tracts. Participants made choices between smaller, sooner (SS)  and larger, later (LL) monetary rewards in a delay-discounting task. Accepting a delay for a larger, later reward correlated with prefrontal inhibition of areas in the striatum:

Adolescence is a developmental period associated with an increase in impulsivity. Impulsivity is a multidimensional construct, and in this study we focus on one of the underlying components: impatience. Impatience can result from (i) disregard of future outcomes and/or (ii) oversensitivity to immediate rewards, but it is not known which of these evaluative processes underlie developmental changes. To distinguish between these two causes, we investigated developmental changes in the structural and functional connectivity of different frontostriatal tracts. We report that adolescents were more impatient on an intertemporal choice task and reported less future orientation, but not more present hedonism, than young adults. Developmental increases in structural connectivity strength in the right dorsolateral prefrontal tract were related to increased negative functional coupling with the striatum and an age-related decrease in discount rates. Our results suggest that mainly increased control, and the integration of future-oriented thought, drives the reduction in impatience across adolescence.

This clip from one of the figures shows the relevant brain areas:

By the way, on the subject of adolescents, I'll point to another piece of work by Baker et. al. on developmental changes in brain network hub connectivity in late adolescence

Unlearning social biases during sleep

Feld and Born note that tenacious implicit prejudices of race or gender drive discrimination seen in the rise of nationalistic groups, excessive police violence against minority group members, persisting unequal pay for women, and sexual harassment all across the developed world. They point to work by Hu et al. that shows how such unwanted attitudes may be persistently changed by a social counterbias training when the fresh memories of this training are systematically reactivated during sleep after training. Here is part of their summary:

Sleep, and specifically deep or slow-wave sleep [non–rapid eye movement (REM) sleep], benefits memory formation by reactivating neuronal traces that were formed during the preceding period of wakefulness. This reactivation of specific memories leads to their strengthening and transformation. Such reactivation can be experimentally induced during slow-wave sleep by presenting cues that were present during the prior period of memory acquisition. Initial studies showed that an odor present during learning of object locations enhances these memories when the participant is reexposed to the odor during slow-wave sleep after learning. These findings have been confirmed in numerous studies investigating different memory systems and also when auditory instead of olfactory cues are used. This basic research has firmly established the possibility of influencing sleep to enhance specific newly learned memories by targeted memory reactivation.

The findings by Hu et al. now suggest that this method can also be used to influence implicit attitudes that are known to typically manifest themselves early during childhood and remain very stable into adulthood. Before a 90-min nap, participants underwent training aimed at countering typical implicit gender and racial biases by learning to associate genders and races with opposing attributes; that is, to associate female faces with science-related words and black faces with “good” words. Critically, presentation of the to-be-learned counterassociations was combined with a sound, which served as a cue to promote the reactivation of the newly learned associations during a subsequent nap while the participant was deep in slow-wave sleep. Only when this sound was re-presented during slow-wave sleep did the posttraining reduction in implicit social bias survive and was even evident 1 week later. These findings are all the more convincing as the authors conducted the reactivation step during a 90-min daytime nap. During normal sleep at night, the effects are expected to be even stronger, owing to the generally deeper and longer periods of slow-wave sleep and REM sleep. Additionally, the accompanying neuroendocrine milieu makes nocturnal sleep even more efficient for memory reinforcement.

Previous studies have shown that such targeted reactivation of memory during sleep can effectively extinguish unwanted behavior such as experimentally induced fear in humans. The present study is the first to demonstrate that this method can be used to break long-lived, highly pervasive response habits deeply rooted in memory and thereby influence behavior at an entirely unconscious level.

A caution:

However, Aldous Huxley's description of a dystopian “brave new world” where young children are conditioned to certain values during sleep reminds us that this research also needs to be guided by ethical considerations. Sleep is a state in which the individual is without willful consciousness and therefore vulnerable to suggestion. Beyond that, Hu et al.'s findings highlight the breadth of possible applications to permanently modify any unwanted behavior by targeted memory reactivation during sleep.