Stimulate your waking memory with an electrical cap

A tiny oscillating electrical stimulation of which we are completely unaware (passed between electrodes on the forehead and jaw) can have the effect of enhancing memory consolidation during waking, an effect shown previously during sleep. The abstract of the open access PNAS article from Kirov et al.:

The application of transcranial slow oscillation stimulation (tSOS; 0.75 Hz) was previously shown to enhance widespread endogenous EEG slow oscillatory activity when applied during a sleep period characterized by emerging endogenous slow oscillatory activity. Processes of memory consolidation typically occurring during this state of sleep were also enhanced. Here, we show that the same tSOS applied in the waking brain also induced an increase in endogenous EEG slow oscillations (0.4–1.2 Hz), although in a topographically restricted fashion. Applied during wakefulness tSOS, additionally, resulted in a marked and widespread increase in EEG theta (4–8 Hz) activity. During wake, tSOS did not enhance consolidation of memories when applied after learning, but improved encoding of hippocampus-dependent memories when applied during learning. We conclude that the EEG frequency and related memory processes induced by tSOS critically depend on brain state. In response to tSOS during wakefulness the brain transposes stimulation by responding preferentially with theta oscillations and facilitated encoding.

Convergence of human and dog evolution, striving to please

Topál et al. perform some fascinating comparative studies that look in dogs for a curious error noted first by Piaget, who showed that 10-month-old humans infants will persist in looking for a toy in box A, where it has been placed several times, even after having been shown that it has been moved to box B, whereas 12-month-old infants do not. This phenomenon marks a developmental milestone in human infant cognition. Adult dogs, like human infants, will persevere in searching erroneously in box A because they regard the placement of the toy by a human experimenter as a social teaching event. By contrast, wolves rapidly learn correctly to search box B. They also observed that infants are able to generalize and thus still persevere when one experimenter places the toy in box A and a second then places the toy in box B. Dogs, however, display episodic learning, and a second experimenter reduces their searching choice to chance. Topál et al. suggest that sensitivity to human communicative signals stems from convergent social evolution of the Homo and the Canis genera.

MindBlog posts in the queue

I think I'll start passing along links to bits of work that I find interesting, but that are so far down my list of potential blog postings that they are unlikely to make it into a regular post. It seems a pity to let them disappear, because I'm aware that a few MindBlog readers with more specialized interests might be interested in some of them.

A study that suggests that increased gamma band (~40 Hz) event-related synchronization is related to, but not sufficient for, consciousness.

Clelland et al. show that synthesis of new nerve cells contributes to formation of spatial memories.

I Heard That Coming: Bendixen et al. show that event related potentials can signal the predictability of pattern in an upcoming a tone sequence.

Watching whales watching us. The evidence suggesting association between sonar and whale deaths is very convincing.

Scientists have now documented behaviors like tool use and cooperative hunting strategies among whales. Orcas, or killer whales, have been found to mourn their own dead. Just three years ago, researchers at Mount Sinai School of Medicine in New York discovered, in the brains of a number of whale species, highly specialized neurons that are linked to, among other things, the use of language and were once thought to be the exclusive property of humans and a few other primates. Indeed, marine biologists are now revealing not only the dizzying variety of vocalizations among a number of whale species but also complex societal structures and cultures.

Vorauer et al. on multiculturalism versus avoidance in influencing the tone of dominant/minority group interactions.

David Sloane Wilson and collaborators on how nice guys can finish last. From the summary in Nature:

Selfish individuals can profit from the altruism of others in their group, and can even exploit a group's resources so much that the resources become exhausted — an event known as the tragedy of the commons...Omar Eldakar, of the University of Arizona in Tucson, and his colleagues have now shown experimentally that aggressive mating in water striders (Aquarius remigis) can result in one such tragedy. Harassment of female water striders by males has previously been shown to drive away females, diminishing the mating success of all males in a group...The team built pools and manipulated the number of aggressive and nonaggressive males in each. They found that hyperaggressive males had greater mating success than those which were not aggressive within mixed pools. But as the number of hyperaggressive insects increased, the mating success of both types decreased.

Testosterone levels and long term career choices

From Sapienzaore et al., more on testosterone, gender, and risk aversion:

Women are generally more risk averse than men. We investigated whether between- and within-gender variation in financial risk aversion was accounted for by variation in salivary concentrations of testosterone and in markers of prenatal testosterone exposure in a sample of >500 MBA students. Higher levels of circulating testosterone were associated with lower risk aversion among women, but not among men. At comparably low concentrations of salivary testosterone, however, the gender difference in risk aversion disappeared, suggesting that testosterone has nonlinear effects on risk aversion regardless of gender. A similar relationship between risk aversion and testosterone was also found using markers of prenatal testosterone exposure. Finally, both testosterone levels and risk aversion predicted career choices after graduation: Individuals high in testosterone and low in risk aversion were more likely to choose risky careers in finance. These results suggest that testosterone has both organizational and activational effects on risk-sensitive financial decisions and long-term career choices.

Moral conviction and religiosity - different in the viscera

An interesting bit from Wisneski et al. :

Theory and research point to different ways moral conviction and religiosity connect to trust in political authorities to decide controversial issues of the day. Specifically, we predicted that stronger moral convictions would be associated with greater distrust in authorities such as the U.S. Supreme Court making the "right" decisions regarding controversial issues. Conversely, we predicted that stronger religiosity would be associated with greater trust in authorities. We tested these hypotheses using a survey of a nationally representative sample of Americans (N = 727) that assessed the degree to which people trusted the U.S. Supreme Court to rule on the legal status of physician-assisted suicide. Results indicated that greater religiosity was associated with greater trust in the U.S. Supreme Court to decide this issue, and that stronger moral convictions about physician-assisted suicide were associated with greater distrust in the U.S. Supreme Court to decide this issue. Also, the processes underlying religious trust and distrust based on moral convictions were more quick and visceral than slow and carefully considered.

The amygdala contributes to both aversive and appetitive arousal

Apparently the "scram!" and "go for it" emotions share some brain wiring. Shabel and Janak note that a large part of the amygdala, whose activation is usually associated with aversive emotions, is also activated during appetitive emotions. Thus there do not appear to be different circuits for the amygdala and autonomic nervous system arousal caused by positive versus aversive stimuli.

The amygdala is important for determining the emotional significance of environmental stimuli. However, the degree to which appetitive and aversive stimuli are processed by the same or different neuronal circuits within the amygdala remains unclear. Here we show that neuronal activity during the expression of classically conditioned appetitive and aversive emotional responses is more similar than expected by chance, despite the different sensory modalities of the eliciting stimuli. We also found that the activity of a large number of cells (> 43%) was correlated with blood pressure, a measure of emotional arousal. Together, our results suggest that a substantial proportion of neuronal circuits within the amygdala can contribute to both appetitive and aversive emotional arousal.

Another reason I live in Wisconsin

I can certify that medical care in Florida (where I now spend the winter) and Texas (where I grew up) is medieval in comparison with Wisconsin. My experience is consonant with a great graphic from a New York Times article on health care costs and quality (click on graphic to enlarge it):

Why fear memories are hard to erase.

Gogolla et al. present evidence that fear memories are protected from erasure (extinction) by an matrix of compounds (chondroitin sulfate proteoglycans) outside of nerve cells in the amygdala, ie. in the extra-cellular matrix:

In adult animals, fear conditioning induces a permanent memory that is resilient to erasure by extinction. In contrast, during early postnatal development, extinction of conditioned fear leads to memory erasure, suggesting that fear memories are actively protected in adults. We show here that this protection is conferred by extracellular matrix chondroitin sulfate proteoglycans (CSPGs) in the amygdala. The organization of CSPGs into perineuronal nets (PNNs) coincided with the developmental switch in fear memory resilience. In adults, degradation of PNNs by chondroitinase ABC specifically rendered subsequently acquired fear memories susceptible to erasure. This result indicates that intact PNNs mediate the formation of erasure-resistant fear memories and identifies a molecular mechanism closing a postnatal critical period during which traumatic memories can be erased by extinction.

These results, together with previous experiments in the visual cortex on visual plasticity, suggest that maturation of the extracellular matrix could be a mechanism used by different brain circuits to change from a malleable to a more crystallized state during development. The presence of a high concentration of CSPGs in the perineuronal nets surrounding inhibitory neurons suggests that inhibitory circuits could play an important role in the developmental control of plasticity.

Lessons from Hell

In the New York Times Book Review Tom Vanderbilt discusses the new book by Rebecca Solnit on the communities (frequently amazingly altruistic) that arise in times of disaster, during which one might have expected the social fabric to rend.

Disasters, for Solnit, do not merely put us in view of apocalypse, but provide glimpses of utopia. They do not merely destroy, but create. “Disasters are extraordinarily generative,” she writes. As the prevailing order — which she elliptically characterizes as advanced global capitalism, full of anomie and isolation — collapses, another order takes shape: “In its place appears a reversion to improvised, collaborative, cooperative and local society.” These “disaster communities” represent something akin to the role William James claimed for “the utopian dreams” of social justice: “They help to break the general reign of hardness, and are slow leavens of a better order.”

A meta-narrative governing official response to the various disasters Solnit examines, from the industrial explosion that devastated Halifax in 1917 to the Mexico City earthquake of 1985 to New York on 9/11, is that cities wracked by disaster need to be protected from rampaging mobs, that government needs to suppress the panicked masses and save the day. But as Solnit illustrates, through an absorbing study of the academic subfield of “disaster sociology,” these Hobbesian (and Holly­wood) beliefs are seldom true.

First, official emergency responders are rarely the first people to respond to an emergency. Second, the central command-and-control model often misinterprets the reality on the ground. Third, the hero motif neglects the role of social capital, a soft-power variable that is played down in disaster management but which might help answer such interesting questions as why Cuba, in contrast to its neighbors (including the United States), responds so well to hurricanes, or why the 2003 New York City blackout was calm while its 1977 equivalent was not...Lastly, there’s the panic myth. A sociologist who set out to research panic in disasters found it was a “vanishingly rare phenomenon,” with cooperation and rational behavior the norm. More typically, panic comes from the top

Walter Kirn on performance enhancing drugs

Check out his account of his own experience.

The ability to stay on task, even the dullest, most numbing task, was Adderall’s first gift to me. It was also its first curse, because it encouraged me to take on work of an increasingly stupefying nature and do it well enough that I got more of it, until I was doing almost no other kind. I can see, though, how harried students might covet this power and why, according to some estimates, a quarter of undergraduates at certain colleges are availing themselves of such stimulants. They’re well aware of the dire economic news — big law firms instituting hiring freezes; whole industries, like publishing, imploding — and it’s natural that they would welcome any advantage in their quests to get the grades that will get them the jobs that will get them the insurance that will get them the medications to do the jobs.

I reached a point with Adderall that reminded me of a warning the United States Marine Corps is said to give its enemies: You can run, but you’ll only die tired...Or graduate tired, in the case of college students. And what’s so wrong with that? The course of a formal education is short but its consequences vast, so why not give it your spirit-crushing all, especially during a fiercely competitive age? “Simply because,” the parent in me says. He’s been there, this man. He’s weary, he’s spent and he just knows.

A cartoon...

Cartoon from the Sept. 7 New Yorker that really struck home for Deric (given that such a tiny fraction of what I am actually thinking ever makes it into this blog):

Some comic relief - talk about costume changes!

The amygdala as the neural source of personal space.

It turns out the amygdala, known to be important in our social interactions, may also be the core of regulating our personal space. (Americans and northern Europeans prefer a larger personal space than southern Europeans, while people with autism tend to unknowingly invade others' personal space.) Here is a a clip from a ScienceNow account of studies on a 42-year-old woman with a rare genetic disorder that destroyed both sides of her amygdala.

In early experiments, the scientists discovered that the woman, referred to as SM, couldn't spot fear in other people's faces; she also rated people as more trustworthy than an average person did. And she was extremely outgoing, "almost to the point where it isn't normal," says team member Daniel Kennedy. Even if she's only just met someone, he says, SM will invade their personal space--touching their arm as she talks or poking their stomach...In the new study, Kennedy and his colleagues more rigorously tested SM's sense of personal space. They compared her with 20 healthy subjects in a series of experiments. In one test, an experimenter slowly walked toward a subject until the subject felt uncomfortable and told the experimenter to stop. SM let experimenters get about twice as close as other subjects did, 0.34 meters versus 0.64 meters, the team reports online this week in Nature Neuroscience. She even felt fine standing nose to nose with an experimenter.

The findings in general support the idea that the amygdala functions as the brakes in social interactions. Here is a figure from the Nature Neuroscience report:

(a) Preference of S.M. (red) was the closest distance to the experimenter (black), among age-, gender-, race- and education-matched controls (purple, n = 5), as well as general comparison subjects (blue, n = 15). (b) S.M.'s mean preferred distance from the experimenter (image drawn to scale). (c) Control participants' mean preferred distance from the experimenter, excluding the three largest outliers (image drawn to scale).

The placebo effect is hard wired into the brain

It has been assumed that 'higher' brain structures linked to expectation are involved with sham treatments that can relieve pain, and natural opioid pathways are known to be important players. Now Eippert and colleagues have imaged the brains of volunteers given a sham ointment to relieve a mild burning pain. Half of them had been treated with naloxone, a chemical that blocks opioid signalling. They observed that placebo-related brain activity occurs in both the prefrontal cortex and more hard-wired areas, such as the amygdala, hypothalamus and parts of the brainstem. Here is more detail from their abstract:

Naloxone reduced both behavioral and neural placebo effects as well as placebo-induced responses in pain-modulatory cortical structures, such as the rostral anterior cingulate cortex (rACC). In a brainstem-specific analysis, we observeda similar naloxone modulation of placebo-induced responses in key structures of the descending pain control system, including the hypothalamus, the periaqueductal gray (PAG), and the rostral ventromedial medulla (RVM). Most importantly, naloxone abolished placebo-induced coupling between rACC and PAG, which predicted both neural and behavioral placebo effects as well as activation of the RVM. These findings show that opioidergic signaling in pain-modulating areas and the projections to downstream effectors of the descending pain control system are crucially important for placebo analgesia.

Brain changes correlating with bipolar disorder.

Three-dimensional model of the brain showing regions of increased volume in the insula, cerebellar vermis, and substantia nigra in individuals with genetic predisposition for bipolar disorder. The image has been reformatted in a style inspired by Vincent van Gogh, the most famous painter with bipolar disorder. For more information, see article by Kempton et al.

How did economists get it so wrong?

Krugman's article in the New York Times Sunday Magazine is really worth reading.

Monkey music

It is generally assumed that music, especially its emotional or affective components, has played an important role in human evolution. The music like component of language, prosody, is central in the "motherese" sounds made to calm human infants. Non-human primates, however, are almost completely indifferent to the sounds of human music. Now Chuck Snowdon here at Wisconsin has collaborated with musician David Teie in an interesting bit of work that demonstrates that cotton-top tamarin monkeys respond to 'tamarin music' synthesized from their affective vocalization sounds. Some interesting samples of the music are here, and here is the abstract of their work, which suggests that affective components in human music may have evolutionary origins in the structure of calls of non-human animals:

Theories of music evolution agree that human music has an affective influence on listeners. Tests of non-humans provided little evidence of preferences for human music. However, prosodic features of speech (‘motherese’) influence affective behaviour of non-verbal infants as well as domestic animals, suggesting that features of music can influence the behaviour of non-human species. We incorporated acoustical characteristics of tamarin affiliation vocalizations and tamarin threat vocalizations into corresponding pieces of music. We compared music composed for tamarins with that composed for humans. Tamarins were generally indifferent to playbacks of human music, but responded with increased arousal to tamarin threat vocalization based music, and with decreased activity and increased calm behaviour to tamarin affective vocalization based music. Affective components in human music may have evolutionary origins in the structure of calls of non-human animals. In addition, animal signals may have evolved to manage the behaviour of listeners by influencing their affective state.

Reducing anxiety caused by early life social isolation.

For rats (and humans) early social isolation causes anxiety-like behavior in adulthood. Work by Lukkes et al. now shows that an antagonist of a brain membrane corticotropin-releasing factor (CRF) receptor (delivered by a brain cannula) partially reverses this effect. Will we be seeing clinical trials of this approach in humans before long? The abstract:

Social isolation of rats during the early part of development increases social anxiety-like behavior in adulthood. Furthermore, early-life social isolation increases the levels of corticotropin-releasing factor (CRF) receptors in the serotonergic dorsal raphe nucleus (dRN) of adult rats. Interactions between serotonin and CRF systems are thought to mediate anxiety behavior. Therefore, we investigated the effects of CRF receptor antagonism within the dRN on social anxiety-like behavior after early-life social isolation. Male rats were reared in isolation or in groups from weaning until midadolescence, and rehoused in groups and allowed to develop into adulthood. Adult rats underwent surgery to implant a drug cannula into the dRN. After recovery from surgery and acclimation to the testing arena, rats were infused with vehicle or the CRF receptor antagonist D-Phe-CRF_(12-41) (50 or 500 ng) into the dRN before a social interaction test. Isolation-reared rats pretreated with vehicle exhibited increased social anxiety-like behavior compared with rats reared in groups. Pretreatment of the dRN with D-Phe-CRF_(12-41) significantly reduced social anxiety-like behaviors exhibited by isolation-reared rats. Overall, this study shows that early-life social stress results in heightened social anxiety-like behavior, which is reversed by CRF antagonism within the dRN. These data suggest that CRF receptor antagonists could provide a potential treatment of stress-related social anxiety.

Our brains have separate hard wired categories for living and non-living objects

Evolution apparently has selected for hard-wiring that separates neural categories for animals — towards which humans have important emotional responses — from those for non-living things. Here is the abstract from Mahon et al.

Distinct regions within the ventral visual pathway show neural specialization for nonliving and living stimuli (e.g., tools, houses versus animals, faces). The causes of these category preferences are widely debated. Using functional magnetic resonance imaging, we find that the same regions of the ventral stream that show category preferences for nonliving stimuli and animals in sighted adults show the same category preferences in adults who are blind since birth. Both blind and sighted participants had larger blood oxygen-level dependent (BOLD) responses inthe medial fusiform gyrus for nonliving stimuli compared to animal stimuli and differential BOLD responses in lateral occipital cortex for animal stimulicompared to nonliving stimuli. These findings demonstrate that the medial-to-lateral bias by conceptual domain in the ventral visual pathway does not require visual experience in order to develop and suggest the operation of innately determined domain-specific constraints on the organization of object knowledge.

Viva Happy Hour!

I have a daily happy hour - a ritual I have imbued with an almost religious aura, in which the single daily drink is sufficient to put me in "the zone." In spite of a literature that mostly says that a little booze is good for you, I still worry that I might be pickling more little gray cells than is desirable. Thus a recent little gem from the American Journal of Geriatric Psychiatry is reassuring. A meta-analysis combining many studies concludes that compared with abstainers, male drinkers reduced their risk for dementia by 45 percent, and women by 27 percent. This is consonant with evidence from other studies that moderate alcohol consumption can increase HDL, or “good cholesterol,” improve blood flow to the brain and decrease blood coagulation. You can check the article for the various caveats to the study.