What drives collective versus individualistic behaviors?

Talheim et al. offer a strikingly simple explanation for why collective versus individualistic behaviors may arise in a given cultural group. Rather than the usual comparison of Western and Asian cultures as a whole, they look at large-scale psychological differences with China, and find that they correlate with the different behavioral requirements of rice versus wheat agriculture:

Cross-cultural psychologists have mostly contrasted East Asia with the West. However, this study shows that there are major psychological differences within China. We propose that a history of farming rice makes cultures more interdependent, whereas farming wheat makes cultures more independent, and these agricultural legacies continue to affect people in the modern world. We tested 1162 Han Chinese participants in six sites and found that rice-growing southern China is more interdependent and holistic-thinking than the wheat-growing north. To control for confounds like climate, we tested people from neighboring counties along the rice-wheat border and found differences that were just as large. We also find that modernization and pathogen prevalence theories do not fit the data.

From Henrich's description of their methods:

To investigate the individualism and analytical thinking in participants from different agricultural regions in China, Talhelm et al. used three tests. They measured analytical thinking with a series of triads. Participants were given a target object, such as a rabbit, and asked which of two other objects it goes with. Analytic thinkers tend to match on categories, so rabbits and dogs go together. Holistic thinkers tend to match on relationships, so rabbits eat carrots. The authors also measured individualism in two ways. First, they asked participants to draw a sociogram, with labeled circles representing themselves and their friends. In this test, individualism is measured implicitly by how much bigger the “self” circle is relative to the average “friends” circle. Second, they assessed the nepotism (in-group loyalty) of participants by asking them about hypothetical scenarios in which they could reward or punish friends and strangers for helpful or harmful action.

Morality and perception speed

Here is an interesting nugget... We are more likely to see a word flashed for a very brief interval if it has moral valence. Words related to morality can be identified after a 40-millisecond peek, but nonmoral words needed an extra 10 ms of exposure. From Gantman and Bavel:

Highlights

• We examined whether moral concerns shape awareness of ambiguous stimuli.
• Participants saw moral and non-moral words in a lexical decision task.
• Moral and non-moral words were matched on length, and frequency in lexicon.
• Participants correctly identified moral words more frequently than non-moral words.
• This experiments suggest that moral values may shape perceptual awareness.

Abstract

People perceive religious and moral iconography in ambiguous objects, ranging from grilled cheese to bird feces. In the current research, we examined whether moral concerns can shape awareness of perceptually ambiguous stimuli. In three experiments, we presented masked moral and non-moral words around the threshold for conscious awareness as part of a lexical decision task. Participants correctly identified moral words more frequently than non-moral words—a phenomenon we term the moral pop-out effect. The moral pop-out effect was only evident when stimuli were presented at durations that made them perceptually ambiguous, but not when the stimuli were presented too quickly to perceive or slowly enough to easily perceive. The moral pop-out effect was not moderated by exposure to harm and cannot be explained by differences in arousal, valence, or extremity. Although most models of moral psychology assume the initial perception of moral stimuli, our research suggests that moral beliefs and values may shape perceptual awareness.

Sluggish cognitive tempo, a new diagnosis du jour?

The drug companies may be finding a new profit center, having maxed out their ability to push pills on the more than 6 million American children who have received a diagnosis of A.D.H.D. (attention deficit hyperactivity disorder, which in my son’s case was evaluated by a sane pediatric psychiatrist who wisely said “Chill, he’s just acting like a kid.”) The new syndrome, summarized by Schwartz, is called sluggish cognitive tempo and said to be characterized by lethargy, daydreaming and slow mental processing. It is the subject of the entire January issue of The Journal of Abnormal Child Psychology.

Papers have proposed that a recognition of sluggish cognitive tempo could help resolve some longstanding confusion about A.D.H.D., which despite having hyperactivity in its name includes about two million children who are not hyperactive, merely inattentive. Some researchers propose that about half of those children would be better classified as having sluggish cognitive tempo, with perhaps one million additional children, who do not meet A.D.H.D.’s criteria now, having the new disorder, too.

The syndrome is not well defined, and many researchers refuse to discuss it, or their financial interests in the condition’s acceptance.

The description I find most intriguing and plausible is of a syndrome that involves extreme mind wandering, perhaps of a brain that is chronically in the “default” mode (described in a number of MindBlog posts) and unable to (or unwilling or too lazy to) activate the “attentional” or goal oriented, direct experiential focus, task positive network appropriately.  (Think about the teenagers behind fast-food counters completely unable to do simple addition and subtraction!). The best therapy for this syndrome would seem to be cognitive or behavioral (i.e. "SHAPE UP!"), rather than another pill to pop.

Drug treatments of this or other behavioral syndromes such as depression have the risk of diminishing personal agency and responsibility, as Iarovici notes:

We walk a thinning line between diagnosing illness and teaching our youth to view any emotional upset as pathological. We need a greater focus on building resilience in emerging adults. We need more scientific studies — spanning years, not months — on the risks and benefits of maintenance treatment in emerging adults.

Formation of new brain cells can erase old memories

Over the past ten years it has been established that generation of new nerve cells in the dentate gyrus portion of our brains' hippocampus is required for hippocampus dependent learning and memory recall. Akers et al. now show that this neurogenesis may also promote forgetting. So, it would appear that while not enough neurogenesis inhibits learning and enhanced neurogenesis enhances it, the ongoing circuit remodeling caused by higher neurogenesis can also make the memories more laible. Thus, there may be a compromise “trade-off” level of neurogenesis that allows good performance for both memory acquisition and retention. The abstract:

Throughout life, new neurons are continuously added to the dentate gyrus. As this continuous addition remodels hippocampal circuits, computational models predict that neurogenesis leads to degradation or forgetting of established memories. Consistent with this, increasing neurogenesis after the formation of a memory was sufficient to induce forgetting in adult mice. By contrast, during infancy, when hippocampal neurogenesis levels are high and freshly generated memories tend to be rapidly forgotten (infantile amnesia), decreasing neurogenesis after memory formation mitigated forgetting. In precocial species, including guinea pigs and degus, most granule cells are generated prenatally. Consistent with reduced levels of postnatal hippocampal neurogenesis, infant guinea pigs and degus did not exhibit forgetting. However, increasing neurogenesis after memory formation induced infantile amnesia in these species.

Nonconscious emotions and first impressions - role for conscious awareness

I just came across this interesting article from Davidson and collaborators at Wisconsin:

Emotions can color people’s attitudes toward unrelated objects in the environment. Existing evidence suggests that such emotional coloring is particularly strong when emotion-triggering information escapes conscious awareness. But is emotional reactivity stronger after nonconscious emotional provocation than after conscious emotional provocation, or does conscious processing specifically change the association between emotional reactivity and evaluations of unrelated objects? In this study, we independently indexed emotional reactivity and coloring as a function of emotional-stimulus awareness to disentangle these accounts. Specifically, we recorded skin-conductance responses to spiders and fearful faces, along with subsequent preferences for novel neutral faces during visually aware and unaware states. Fearful faces increased skin-conductance responses comparably in both stimulus-aware and stimulus-unaware conditions. Yet only when visual awareness was precluded did skin-conductance responses to fearful faces predict decreased likability of neutral faces. These findings suggest a regulatory role for conscious awareness in breaking otherwise automatic associations between physiological reactivity and evaluative emotional responses.

Language universals at birth.

Fascinating observations from Gómez et al. showing that human babies are born with linguistic biases concerning syllable structure:

The evolution of human languages is driven both by primitive biases present in the human sensorimotor systems and by cultural transmission among speakers. However, whether the design of the language faculty is further shaped by linguistic biological biases remains controversial. To address this question, we used near-infrared spectroscopy to examine whether the brain activity of neonates is sensitive to a putatively universal phonological constraint. Across languages, syllables like blif are preferred to both lbif and bdif. Newborn infants (2–5 d old) listening to these three types of syllables displayed distinct hemodynamic responses in temporal-perisylvian areas of their left hemisphere. Moreover, the oxyhemoglobin concentration changes elicited by a syllable type mirrored both the degree of its preference across languages and behavioral linguistic preferences documented experimentally in adulthood. These findings suggest that humans possess early, experience-independent, linguistic biases concerning syllable structure that shape language perception and acquisition.

GABA predicts time perception.

Individuals can vary widely in their ability to detect sub-second visual stimuli, and most cognitive training and exercise regimes have exercises designed to enhance detection of shorter (50-200 millisecond) intervals. Terhune et al. make the interesting observation that this variability correlates with the resting state levels of the inhibitory transmitter GABA (gamma-amino butyric acid)in our visual cortex, such that elevated GABA is associated with underestimating the duration of subsecond visual intervals:

Our perception of time constrains our experience of the world and exerts a pivotal influence over a myriad array of cognitive and motor functions. There is emerging evidence that the perceived duration of subsecond intervals is driven by sensory-specific neural activity in human and nonhuman animals, but the mechanisms underlying individual differences in time perception remain elusive. We tested the hypothesis that elevated visual cortex GABA impairs the coding of particular visual stimuli, resulting in a dampening of visual processing and concomitant positive time-order error (relative underestimation) in the perceived duration of subsecond visual intervals. Participants completed psychophysical tasks measuring visual interval discrimination and temporal reproduction and we measured in vivo resting state GABA in visual cortex using magnetic resonance spectroscopy. Time-order error selectively correlated with GABA concentrations in visual cortex, with elevated GABA associated with a rightward horizontal shift in psychometric functions, reflecting a positive time-order error (relative underestimation). These results demonstrate anatomical, neurochemical, and task specificity and suggest that visual cortex GABA contributes to individual differences in time perception.

More on the rejuvenating power of young blood...

Since my "fountain of youth" post in 2011 there has been a burst of research showing that factors in the blood of younger animals can actually reverse the aging process in older ones. Carl Zimmer points to several of the studies. Wagers and collaborators find that restoring levels of a circulating protein growth differentiation factor 11 (GDF11), a skeletal muscle rejuvenating factor whose levels normally decline with age, reverses muscle dysfunction by increased stength and endurance exercise capacity. Further, GDF11 alone can improve the cerebral vasculature and enhance neurogenesis. Villeda et al find that structural and cognitive enhancements elicited by exposure to young blood are mediated, in part, by activation of the cyclic AMP response element binding protein (Creb) in the aged hippocampus.

So, should we all be rushing out to shoot ourselves up with injections of GDF!!? Maybe not... waking up too many stem cells to start multiplying might increase the incidence of cancer.

Brain activity display in the spirit of P.T. Barnum

Carl Zimmer points to some amazing brain graphics, notably one from Gazzaley's lab. You should use the gear symbol to slow down the graphic, and set the resolution to high definition if your computer supports it. Setting the screen to full display and frequently pausing the play through lets you see all sorts of moving flashing lights going to and from familiar brain areas, but what's the behavioral or subjective correlate??


 This is great show-biz, but I wish Zimmer's statement that "the volunteer was simply asked to open and shut her eyes and open and close her hand." appeared here and that the moving graphics were labelled "eye shutting" "eye opening" "hand opening" "hand closing," and could they maybe tell us which colors refer to which frequency bands? Very frustrating. Maybe if I dug a bit more diligently on their websites I could find the information, but at this point I'm not willing to spend more time on it. Here is the description provided:

This is an anatomically-realistic 3D brain visualization depicting real-time source-localized activity (power and "effective" connectivity) from EEG (electroencephalographic) signals. Each color represents source power and connectivity in a different frequency band (theta, alpha, beta, gamma) and the golden lines are white matter anatomical fiber tracts. Estimated information transfer between brain regions is visualized as pulses of light flowing along the fiber tracts connecting the regions.

The modeling pipeline includes MRI (Magnetic Resonance Imaging) brain scanning to generate a high-resolution 3D model of an individual's brain, skull, and scalp tissue, DTI (Diffusion Tensor Imaging) for reconstructing white matter tracts, and BCILAB (http://sccn.ucsd.edu/wiki/BCILAB) / SIFT (http://sccn.ucsd.edu/wiki/SIFT) to remove artifacts and statistically reconstruct the locations and dynamics (amplitude and multivariate Granger-causal (http://www.scholarpedia.org/article/G...) interactions) of multiple sources of activity inside the brain from signals measured at electrodes on the scalp (in this demo, a 64-channel "wet" mobile system by Cognionics/BrainVision (http://www.cognionics.com)).

The final visualization is done in Unity and allows the user to fly around and through the brain with a gamepad while seeing real-time live brain activity from someone wearing an EEG cap.

We transfer reward in a bottom-up search task to a top-down search task.

Lee and Shomstein make the interesting observation that a reward-based contingency learned in a bottom-up search task can be transferred to a subsequent top-down search task. They define the two kinds of search task in their introduction:

Research has demonstrated that the allocation of attention is controlled by two partially segregated networks of brain areas. The top-down attention system, which recruits parts of the intraparietal and superior frontal cortices, is specialized for selecting stimuli on the basis of cognitive factors, such as current goals and expectations. The bottom-up attention system, by contrast, recruits the temporoparietal and inferior frontal cortices, and is involved in processing stimuli on the basis of stimulus-driven factors, such as physical salience and novelty.

Here is their abstract:

Recent evidence has suggested that reward modulates bottom-up and top-down attentional selection and that this effect persists within the same task even when reward is no longer offered. It remains unclear whether reward effects transfer across tasks, especially those engaging different modes of attention. We directly investigated whether reward-based contingency learned in a bottom-up search task was transferred to a subsequent top-down search task, and probed the nature of the transfer mechanism. Results showed that a reward-related benefit established in a pop-out-search task was transferred to a conjunction-search task, increasing participants’ efficiency at searching for targets previously associated with a higher level of reward. Reward history influenced search efficiency by enhancing both target salience and distractor filtering, depending on whether the target and distractors shared a critical feature. These results provide evidence for reward-based transfer between different modes of attention and strongly suggest that an integrated priority map based on reward information guides both top-down and bottom-up attention.

Gene expression changes in expert meditators?

Interesting data from an international collaboration. (Although, it seems the more useful design would have been to do a double blind experiment in which half of a group of experienced meditators performed the intensive practice while the other half, in a similar environment, did not.)

 Background

A growing body of research shows that mindfulness meditation can alter neural, behavioral and biochemical processes. However, the mechanisms responsible for such clinically relevant effects remain elusive.

Methods

Here we explored the impact of a day of intensive practice of mindfulness meditation in experienced subjects (n = 19) on the expression of circadian, chromatin modulatory and inflammatory genes in peripheral blood mononuclear cells (PBMC). In parallel, we analyzed a control group of subjects with no meditation experience who engaged in leisure activities in the same environment (n = 21). PBMC from all participants were obtained before (t1) and after (t2) the intervention (t2 − t1 = 8 h) and gene expression was analyzed using custom pathway focused quantitative-real time PCR assays. Both groups were also presented with the Trier Social Stress Test (TSST).

Results

Core clock gene expression at baseline (t1) was similar between groups and their rhythmicity was not influenced in meditators by the intensive day of practice. Similarly, we found that all the epigenetic regulatory enzymes and inflammatory genes analyzed exhibited similar basal expression levels in the two groups. In contrast, after the brief intervention we detected reduced expression of histone deacetylase genes (HDAC 2, 3 and 9), alterations in global modification of histones (H4ac; H3K4me3) and decreased expression of pro-inflammatory genes (RIPK2 and COX2) in meditators compared with controls. We found that the expression of RIPK2 and HDAC2 genes was associated with a faster cortisol recovery to the TSST in both groups.

Conclusions

The regulation of HDACs and inflammatory pathways may represent some of the mechanisms underlying the therapeutic potential of mindfulness-based interventions. Our findings set the foundation for future studies to further assess meditation strategies for the treatment of chronic inflammatory conditions.

The smell of sickness.

Olsson et al. demonstrate the existence of a olfactory signal of illness, a aversive body odor that can signal other humans to keep their distance from a diseased person, but they do not identify the volatile chemicals that must be involved.:

Observational studies have suggested that with time, some diseases result in a characteristic odor emanating from different sources on the body of a sick individual. Evolutionarily, however, it would be more advantageous if the innate immune response were detectable by healthy individuals as a first line of defense against infection by various pathogens, to optimize avoidance of contagion. We activated the innate immune system in healthy individuals by injecting them with endotoxin (lipopolysaccharide). Within just a few hours, endotoxin-exposed individuals had a more aversive body odor relative to when they were exposed to a placebo. Moreover, this effect was statistically mediated by the individuals’ level of immune activation. This chemosensory detection of the early innate immune response in humans represents the first experimental evidence that disease smells and supports the notion of a “behavioral immune response” that protects healthy individuals from sick ones by altering patterns of interpersonal contact.

Out of body, out of mind.

Bergouignan et al. do a neat experiment in which they test how well study participants remember a presentation when they experience being in their own bodies versus out of their bodies looking at the presentation from another perspective. They find that if an event is experienced from an 'out-of-body' perspective, it is remembered less well and its recall does not induce the usual pattern of hippocampal activation. This means that hippocampus-based episodic memory depends on the perception of the world from within our own bodies, and that a dissociative experience during encoding blocks the memory-forming mechanism. Here is their abstract, followed by a description of how they set up out of body experience.

Theoretical models have suggested an association between the ongoing experience of the world from the perspective of one’s own body and hippocampus-based episodic memory. This link has been supported by clinical reports of long-term episodic memory impairments in psychiatric conditions with dissociative symptoms, in which individuals feel detached from themselves as if having an out-of-body experience. Here, we introduce an experimental approach to examine the necessary role of perceiving the world from the perspective of one’s own body for the successful episodic encoding of real-life events. While participants were involved in a social interaction, an out-of-body illusion was elicited, in which the sense of bodily self was displaced from the real body to the other end of the testing room. This condition was compared with a well-matched in-body illusion condition, in which the sense of bodily self was colocalized with the real body. In separate recall sessions, performed ∼1 wk later, we assessed the participants’ episodic memory of these events. The results revealed an episodic recollection deficit for events encoded out-of-body compared with in-body. Functional magnetic resonance imaging indicated that this impairment was specifically associated with activity changes in the posterior hippocampus. Collectively, these findings show that efficient hippocampus-based episodic-memory encoding requires a first-person perspective of the natural spatial relationship between the body and the world. Our observations have important implications for theoretical models of episodic memory, neurocognitive models of self, embodied cognition, and clinical research into memory deficits in psychiatric disorders.

The setup:

During the life events to be remembered (“encoding sessions”), the participants sat in a chair and wore a set of head-mounted displays (HMDs) and earphones, which were connected to two closed-circuit television (CCTV) cameras and to an advanced “dummy-head microphone,” respectively. This technology enabled the participants to see and hear the testing room in three dimensions from the perspective of the cameras mounted with the dummy head microphones. The cameras were either placed immediately above and behind the actual head of the participant, creating an experience of the room from the perspective of the real body (in-body condition), or the cameras were placed 2 m in front or to the side of the participant, thus making the participants experience the room and the individuals in it as an observer outside of their real body (out-of-body condition). To induce the strong illusion of being fully located in one of these two locations and sensing an illusory body in this place, we repetitively moved a rod toward a location below the cameras and synchronously touched the participant’s chest for a period of 70 s, which provided congruent multisensory stimulation to elicit illusory perceptions. The illusion was maintained for 5 min, during which the ecologically valid life events took place (see next section); throughout this period, the participant received spatially congruent visual and auditory information via the synchronized HMDs and dummy head microphones, which further facilitated the maintenance of the illusion.

Oxytocin promotes group-serving dishonesty

Like Lewis Carroll's Wonderland, the oxytocin story gets curiouser and curiouser.... this from Shalvi and De Dreu:

To protect and promote the well-being of others, humans may bend the truth and behave unethically. Here we link such tendencies to oxytocin, a neuropeptide known to promote affiliation and cooperation with others. Using a simple coin-toss prediction task in which participants could dishonestly report their performance levels to benefit their group’s outcome, we tested the prediction that oxytocin increases group-serving dishonesty. A double-blind, placebo-controlled experiment allowing individuals to lie privately and anonymously to benefit themselves and fellow group members showed that healthy males (n = 60) receiving intranasal oxytocin, rather than placebo, lied more to benefit their group, and did so faster, yet did not necessarily do so because they expected reciprocal dishonesty from fellow group members. Treatment effects emerged when lying had financial consequences and money could be gained; when losses were at stake, individuals in placebo and oxytocin conditions lied to similar degrees. In a control condition (n = 60) in which dishonesty only benefited participants themselves, but not fellow group members, oxytocin did not influence lying. Together, these findings fit a functional perspective on morality revealing dishonesty to be plastic and rooted in evolved neurobiological circuitries, and align with work showing that oxytocin shifts the decision-maker’s focus from self to group interests. These findings highlight the role of bonding and cooperation in shaping dishonesty, providing insight into when and why collaboration turns into corruption.

Aesop's crow - evidence of causal understanding

Jelbert et al. show even further smarts in the New Caledonian Crow I've mentioned in several previous posts.

Understanding causal regularities in the world is a key feature of human cognition. However, the extent to which non-human animals are capable of causal understanding is not well understood. Here, we used the Aesop's fable paradigm – in which subjects drop stones into water to raise the water level and obtain an out of reach reward – to assess New Caledonian crows' causal understanding of water displacement. We found that crows preferentially dropped stones into a water-filled tube instead of a sand-filled tube; they dropped sinking objects rather than floating objects; solid objects rather than hollow objects, and they dropped objects into a tube with a high water level rather than a low one. However, they failed two more challenging tasks which required them to attend to the width of the tube, and to counter-intuitive causal cues in a U-shaped apparatus. Our results indicate that New Caledonian crows possess a sophisticated, but incomplete, understanding of the causal properties of displacement, rivaling that of 5–7 year old children.

A blood test for Alzheimers disease?

Mapstone et al. have identified a set of 10 lipids whose levels predict, with an accuracy of over 90%, whether or not an older individual will develop mild cognitive impairment or Alzheimer's disease within 2–3 years. If this work is confirmed by other independent and more extensive studies, we may be seeing a clinical test within a few years. Would this 72 year old take such a test? Probably so, because avoiding the possible bad news would mean I might be less likely to get financial, legal, personal stuff in order (things like planing for care and informing family.)

Alzheimer's disease causes a progressive dementia that currently affects over 35 million individuals worldwide and is expected to affect 115 million by 2050. There are no cures or disease-modifying therapies, and this may be due to our inability to detect the disease before it has progressed to produce evident memory loss and functional decline. Biomarkers of preclinical disease will be critical to the development of disease-modifying or even preventative therapies. Unfortunately, current biomarkers for early disease, including cerebrospinal fluid tau and amyloid-β levels, structural and functional magnetic resonance imaging and the recent use of brain amyloid imaging or inflammaging, are limited because they are either invasive, time-consuming or expensive. Blood-based biomarkers may be a more attractive option, but none can currently detect preclinical Alzheimer's disease with the required sensitivity and specificity. Herein, we describe our lipidomic approach to detecting preclinical Alzheimer's disease in a group of cognitively normal older adults. We discovered and validated a set of ten lipids from peripheral blood that predicted phenoconversion to either amnestic mild cognitive impairment or Alzheimer's disease within a 2–3 year timeframe with over 90% accuracy. This biomarker panel, reflecting cell membrane integrity, may be sensitive to early neurodegeneration of preclinical Alzheimer's disease.

Wave of the future - trusting machines that talk to us.

We're reading that in 10 years we might be able to buy autonomous cars that do the driving for us. Waytz et al. do an interesting study of the psychological consequence of endowing such vehicles with a voice. They monitor self report of emotions and fluctuations in heart rate while subjects either operate a driving simulator themselves, or become the passenger driven by an autonomous that does or doesn't speak to them. Not surprisingly, audio communication increases the sense of liking and trust. Also in the aftermath of a simulated collision programmed so as to be unavoidable, the vocal vehicle is more likely to be absolved of blame. The subjects have attributed human agency to a machine, which I was just doing while driving back to Madison WI from my winter nest in Fort Lauderdale, and found myself cursing the teutonic female voice of my GPS navigator. Here are their highlights and abstract:

Highlights
-Anthropomorphism of a car predicts trust in that car.
-Trust is reflected in behavioral, physiological, and self-report measures.
-Anthropomorphism also affects attributions of responsibility/punishment.  

Abstract 

Sophisticated technology is increasingly replacing human minds to perform complicated tasks in domains ranging from medicine to education to transportation. We investigated an important theoretical determinant of people's willingness to trust such technology to perform competently—the extent to which a nonhuman agent is anthropomorphized with a humanlike mind—in a domain of practical importance, autonomous driving. Participants using a driving simulator drove either a normal car, an autonomous vehicle able to control steering and speed, or a comparable autonomous vehicle augmented with additional anthropomorphic features—name, gender, and voice. Behavioral, physiological, and self-report measures revealed that participants trusted that the vehicle would perform more competently as it acquired more anthropomorphic features. Technology appears better able to perform its intended design when it seems to have a humanlike mind. These results suggest meaningful consequences of humanizing technology, and also offer insights into the inverse process of objectifying humans.

Brain abnormalities caused by marijuana use.

Numerous studies have shown that cannabis use is associated with impairments of cognitive functions, including learning and memory, attention, and decision-making. Animal studies show structural changes in brain regions underlying these functions after exposure to Δ9-tetrahydrocannabinol (THC). Now, a sobering bit of information on structural changes in human brains from Gilman et al.:

Marijuana is the most commonly used illicit drug in the United States, but little is known about its effects on the human brain, particularly on reward/aversion regions implicated in addiction, such as the nucleus accumbens and amygdala. Animal studies show structural changes in brain regions such as the nucleus accumbens after exposure to Δ9-tetrahydrocannabinol, but less is known about cannabis use and brain morphometry in these regions in humans. We collected high-resolution MRI scans on young adult recreational marijuana users and nonusing controls and conducted three independent analyses of morphometry in these structures: (1) gray matter density using voxel-based morphometry, (2) volume (total brain and regional volumes), and (3) shape (surface morphometry). Gray matter density analyses revealed greater gray matter density in marijuana users than in control participants in the left nucleus accumbens extending to subcallosal cortex, hypothalamus, sublenticular extended amygdala, and left amygdala, even after controlling for age, sex, alcohol use, and cigarette smoking. Trend-level effects were observed for a volume increase in the left nucleus accumbens only. Significant shape differences were detected in the left nucleus accumbens and right amygdala. The left nucleus accumbens showed salient exposure-dependent alterations across all three measures and an altered multimodal relationship across measures in the marijuana group. These data suggest that marijuana exposure, even in young recreational users, is associated with exposure-dependent alterations of the neural matrix of core reward structures and is consistent with animal studies of changes in dendritic arborization.

Brain activity underlying subjective awareness

Hill and He devise and interesting paradigm to distinguish brain activities directly contributing to conscious perception from brain activities that precede or follow it. They do this by examining trial by trial objective performance, subjective awareness, and the confidence level of subjective awareness. They find that widely distributed slow cortical potentials in the < 4 Hz (delta) range - i.e. brain activity waves taking longer than a quarter of a second - correlate with subjective awareness, even after the effects of objective performance and confidence (contributed by more transient brain activity) were both removed. Here is their abstract:

Despite intense recent research, the neural correlates of conscious visual perception remain elusive. The most established paradigm for studying brain mechanisms underlying conscious perception is to keep the physical sensory inputs constant and identify brain activities that correlate with the changing content of conscious awareness. However, such a contrast based on conscious content alone would not only reveal brain activities directly contributing to conscious perception, but also include brain activities that precede or follow it. To address this issue, we devised a paradigm whereby we collected, trial-by-trial, measures of objective performance, subjective awareness, and the confidence level of subjective awareness. Using magnetoencephalography recordings in healthy human volunteers, we dissociated brain activities underlying these different cognitive phenomena. Our results provide strong evidence that widely distributed slow cortical potentials (SCPs) correlate with subjective awareness, even after the effects of objective performance and confidence were both removed. The SCP correlate of conscious perception manifests strongly in its waveform, phase, and power. In contrast, objective performance and confidence were both contributed by relatively transient brain activity. These results shed new light on the brain mechanisms of conscious, unconscious, and metacognitive processing.

Blocking facial muscle movement compromizes detecting and having emotions

Rychlowska et al. show that blocking facial mimicry makes true and false smiles look the same:

Recent research suggests that facial mimicry underlies accurate interpretation of subtle facial expressions. In three experiments, we manipulated mimicry and tested its role in judgments of the genuineness of true and false smiles. A first experiment used facial EMG to show that a new mouthguard technique for blocking mimicry modifies both the amount and the time course of facial reactions. In two further experiments, participants rated true and false smiles either while wearing mouthguards or when allowed to freely mimic the smiles with or without additional distraction, namely holding a squeeze ball or wearing a finger-cuff heart rate monitor. Results showed that blocking mimicry compromised the decoding of true and false smiles such that they were judged as equally genuine. Together the experiments highlight the role of facial mimicry in judging subtle meanings of facial expressions.

And, Richard Friedman points to work showing that paralyzing the facial muscles central to frowning with Botox provides relief from depression. Information between brain and muscle clearly flows both ways.

In a study forthcoming in the Journal of Psychiatric Research, Eric Finzi, a cosmetic dermatologist, and Norman Rosenthal, a professor of psychiatry at Georgetown Medical School, randomly assigned a group of 74 patients with major depression to receive either Botox or saline injections in the forehead muscles whose contraction makes it possible to frown. Six weeks after the injection, 52 percent of the subjects who got Botox showed relief from depression, compared with only 15 percent of those who received the saline placebo.