This blog reports new ideas and work on mind, brain, behavior, psychology, and politics - as well as random curious stuff. (Try the Dynamic Views at top of right column.)
Thursday, September 10, 2009
Another reason I live in Wisconsin
Why fear memories are hard to erase.
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
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
Wednesday, September 09, 2009
Walter Kirn on performance enhancing drugs
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...
Tuesday, September 08, 2009
The amygdala as the neural source of personal space.
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
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.
How did economists get it so wrong?
Monday, September 07, 2009
Monkey music
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.
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
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.
Friday, September 04, 2009
Viva Happy Hour!
Happiness and unhappiness in East and West
Cultural folk models of happiness and unhappiness are likely to have important bearings on social cognition and social behavior. At present, however, little is known about the nature of these models. Here, the authors systematically analyzed American and Japanese participants’ spontaneously produced descriptions of the two emotions and observed, as predicted, that whereas Americans associated positive hedonic experience of happiness with personal achievement, Japanese associated it with social harmony. Furthermore, Japanese were more likely than Americans to mention both social disruption and transcendental reappraisal as features of happiness. As also predicted, unlike happiness, descriptions of unhappiness included various culture-specific coping actions: Whereas Americans focused on externalizing behavior (e.g., anger and aggression), Japanese highlighted transcendental reappraisal and self-improvement.
Brief early exposure to high fat diet changes long term dietary habits
Overweight and obesity in the United States continues to grow at epidemic rates in large part due to the overconsumption of calorically-dense palatable foods. Identification of factors influencing long-term macronutrient preferences may elucidate points of prevention and behavioral modification. In our current study, we examined the adult macronutrient preferences of mice acutely exposed to a high fat diet during the third postnatal week. We hypothesized that the consumption of a high fat diet during early life would alter the programming of central pathways important in adult dietary preferences. As adults, the early-exposed mice displayed a significant preference for a diet high in fat compared to controls. This effect was not due to diet familiarity as mice exposed to a novel high carbohydrate diet during this same early period failed to show differences in macronutrient preferences as adults. The increased intake of high fat diet in early exposed mice was specific to dietary preferences as no changes were detected for total caloric intake or caloric efficiency. Mechanistically, mice exposed to a high fat diet during early life exhibited significant alterations in biochemical markers of dopamine signaling in the nucleus accumbens, including changes in levels of phospho–dopamine and cyclic AMP-regulated phosphoprotein, molecular weight 32 kDa (DARPP-32) threonine-75, ΔFosB, and cyclin-dependent kinase 5. These results support our hypothesis that even brief early life exposure to calorically-dense palatable diets alters long-term programming of central mechanisms important in dietary preferences and reward. These changes may underlie the passive overconsumption of high fat foods contributing to the increasing body mass in the western world.
Thursday, September 03, 2009
Weight as an embodyment of importance.
Participants provided judgments of importance while they held either a heavy or a light clipboard. Holding a heavy clipboard increased judgments of monetary value (Study 1) and made participants consider fair decision-making procedures to be more important (Study 2). It also caused more elaborate thinking, as indicated by higher consistency between related judgments (Study 3) and by greater polarization of agreement ratings for strong versus weak arguments (Study 4). In line with an embodied perspective on cognition, these findings suggest that, much as weight makes people invest more physical effort in dealing with concrete objects, it also makes people invest more cognitive effort in dealing with abstract issues.
Gene variants that correlate with both psychosis and creativity?
Fleeing from Facebook
Is Facebook doomed to someday become an online ghost town, run by zombie users who never update their pages and packs of marketers picking at the corpses of social circles they once hoped to exploit? Sad, if so. Though maybe fated, like the demise of a college clique.