Thursday, October 31, 2013

Scary music for Halloween - Dance Macabre

You should have a look at the 13 scariest pieces of classical music for Halloween, assembled by Limelight Magazine. It is hard for me to select a favorite, but I will point to this classic Disney cartoon of Saint-Saens Dance Macabre:
Saint-Saëns’s creepy 1874 tone poem is a Halloween classic, depicting the revelry of the Grim Reaper at midnight every year at this time. With his cursed fiddle, Death summons the dead from their graves to kick up their heals until dawn. In this vintage Disney animation, listen out for the xylophone sound of rattling bones.

Wednesday, October 30, 2013

Finding a protein linking exercise to brain health

Yet another candidate for a life enhancing drug? ...perhaps a protein that mimics the effect of the protein FNDC5, which is produced by muscular exertion and in turn boosts the level of a brain-health protein, BDNF (brain-derived neurotrophic protein) in the dentate gyrus of the hippocampus. Here is the summary and abstract from Wrann et al. with some technical details:
Exercise induces FNDC5 in the hippocampus.
PGC-1α regulates neuronal Fndc5 gene expression in vitro and in vivo.
FNDC5 positively regulates the expression of the important neurotrophin BDNF.
Peripheral delivery of FNDC5 via adenoviral vectors induces Bdnf in the hippocampus.
Exercise can improve cognitive function and has been linked to the increased expression of brain-derived neurotrophic factor (BDNF). However, the underlying molecular mechanisms driving the elevation of this neurotrophin remain unknown. Here we show that FNDC5, a previously identified muscle protein that is induced in exercise and is cleaved and secreted as irisin, is also elevated by endurance exercise in the hippocampus of mice. Neuronal Fndc5 gene expression is regulated by PGC-1α, and Pgc1a−/− mice show reduced Fndc5 expression in the brain. Forced expression of FNDC5 in primary cortical neurons increases Bdnf expression, whereas RNAi-mediated knockdown of FNDC5 reduces Bdnf. Importantly, peripheral delivery of FNDC5 to the liver via adenoviral vectors, resulting in elevated blood irisin, induces expression of Bdnf and other neuroprotective genes in the hippocampus. Taken together, our findings link endurance exercise and the important metabolic mediators, PGC-1α and FNDC5, with BDNF expression in the brain.

Tuesday, October 29, 2013

"Only Disconnect" - The pathology of digital of connectivity

Alas, it seems increasingly clear that to follow E.M. Forster’s dictum “Only Connect” (i.e. with humans in person, what our emotional brain evolved to do.) it is also necessary to follow Evgeny Morozov’s more recent dictum (and title of his review of several several books) “Only Disconnect.” (with the pseudo-connectivity of our tweets,followers, facebook friends, blog hits, google+ plus counts, Klout numbers, Thumbs up or downs, Shout outs, Likes, etc.). I will pass on some clips from Morozov's article. After noting descriptions by the Weimar Republic's literary luminary Siegfried Kracauer of the public over stimulation of his day, and his remedy of 'radical boredom' as an antidote, Morozov continues:
These days, "the state of permanent receptivity" has become the birthright of anyone with a smartphone. We are under constant assault by "interestingness"...the anti-boredom lobby has all but established its headquarters in Silicon Valley...
Information overload can bore us as easily as information underload. But this form of boredom, mediated boredom, doesn't provide time to think; it just produces a craving for more information in order to suppress it.
Morozov quotes from French philosopher Henri Lefebvre from the early 1960's
Today everything comes to an end virtually as soon as it begins, and vanishes almost as soon as it appears..As interest in it gets progressively weaker, so news becomes more rapid and concentrated, until finally, at the end of a shorter and shorter period, it wears itself..We have the phoney "new" faked novelty..The confusion between triviality which no longer appears trivial and sensationalism which is made to appear ordinary is cleverly organized. New shrinks to the size of the socially instantaneous, and the immediate instant tends to disappear in an instant which has already passed.
And then, Morozov notes:
I should admit that I'm something of a "contemplative computing" devotee, which is also to say, a distraction addict. Last year, I bought a safe with a built-in timer that I use to lock away my smartphone and Internet cable for days on end. (Tools like Freedom didn't work for me - they are too easy to circumvent.
What's needed is a modern-day counterpart to the anti-noise campaigners of a century ago.. Information deserve its own environmentalism....what is modernity if not a collection of pickets of silence and distraction? Consider the Amtrak train: yes, we get Wi-Fi, but we also get the Quiet Car..Both radical boredom and radical distraction can get us closer to "authentic rapture within the inauthentic domain." The trick is not to settle for their tepid, mediocre versions.
Likewise, the possibility of controlled disconnection - embedded in software like Freedom and harware like my safe - reassures us that our task lists and deadlines are manageable, if we approach them with distraction. Like travel and dance, both are illusions concocted by modernity... Life in the New Digital Age might be disorienting, but at least it isn't nasty, brutish, and short. Not in the Quiet Car, anyway.

Monday, October 28, 2013

Perspective taking can turn competitors unethical

An interesting bit from Pierce et al.:
Perspective taking is often the glue that binds people together. However, we propose that in competitive contexts, perspective taking is akin to adding gasoline to a fire: It inflames already-aroused competitive impulses and leads people to protect themselves from the potentially insidious actions of their competitors. Overall, we suggest that perspective taking functions as a relational amplifier. In cooperative contexts, it creates the foundation for prosocial impulses, but in competitive contexts, it triggers hypercompetition, leading people to prophylactically engage in unethical behavior to prevent themselves from being exploited. The experiments reported here establish that perspective taking interacts with the relational context—cooperative or competitive—to predict unethical behavior, from using insidious negotiation tactics to materially deceiving one’s partner to cheating on an anagram task. In the context of competition, perspective taking can pervert the age-old axiom “do unto others as you would have them do unto you” into “do unto others as you think they will try to do unto you.”

Thursday, October 24, 2013

Oxytocin, gentle human touch, and social impression.

Another bit of information from Leknes and collaborators, expanding on their work mentioned in a recent post:
Interpersonal touch is frequently used for communicating emotions, strengthen social bonds and to give others pleasure. The neuropeptide oxytocin increases social interest, improves recognition of others’ emotions, and it is released during touch. Here, we investigated how oxytocin and gentle human touch affect social impressions of others, and vice versa, how others’ facial expressions and oxytocin affect touch experience. In a placebo-controlled crossover study using intranasal oxytocin, 40 healthy volunteers viewed faces with different facial expressions along with concomitant gentle human touch or control machine touch, while pupil diameter was monitored. After each stimulus pair, participants rated the perceived friendliness and attractiveness of the faces, perceived facial expression, or pleasantness and intensity of the touch. After intranasal oxytocin treatment, gentle human touch had a sharpening effect on social evaluations of others relative to machine touch, such that frowning faces were rated as less friendly and attractive, whereas smiling faces were rated as more friendly and attractive. Conversely, smiling faces increased, whereas frowning faces reduced, pleasantness of concomitant touch – the latter effect being stronger for human touch. Oxytocin did not alter touch pleasantness. Pupillary responses, a measure of attentional allocation, were larger to human touch than to equally intense machine touch, especially when paired with a smiling face. Overall, our results point to mechanisms important for human affiliation and social bond formation.

Wednesday, October 23, 2013

A genetic predisposition to note the negative.

Another interesting example of viewing the world through gene-colored glasses...Todd et al. note an interesting behavioral correlation involving a gene variant, carried by ~50% of Caucasians, of subtype B of the α2-adrenergic receptor: people with the variant are more likely to take note of negative events. They use the "attentional blink" paradigm to reach this conclusion:
The attentional a phenomenon in which participants are typically unable to identify a target stimulus when it is presented less than approximately 500 ms after a previous target in a rapid stream of stimuli. One interpretation of this blink is that it reflects a failure of attentional filters to consolidate the second target into working memory when it appears too quickly after the first, which results in impaired perceptual awareness. When the second target has emotional significance, there is a reduced attentional blink, or an emotional sparing. This emotional sparing, or reduction of the attentional blink for emotional stimuli relative to neutral stimuli, can be seen as the relative tuning of selective attention to affective stimuli.
Here is their abstract (which contains the fairly common error of using "are responsible for" instead of the more correct "correlate with"):
Emotionally enhanced memory and susceptibility to intrusive memories after trauma have been linked to a deletion variant (i.e., a form of a gene in which certain amino acids are missing) of ADRA2B, the gene encoding subtype B of the α2-adrenergic receptor, which influences norepinephrine activity. We examined in 207 participants whether variations in this gene are responsible for individual differences in affective influences on initial encoding that alter perceptual awareness. We examined the attentional blink, an attentional impairment during rapid serial visual presentation, for negatively arousing, positively arousing, and neutral target words. Overall, the attentional blink was reduced for emotional targets for ADRA2B-deletion carriers and noncarriers alike, which reveals emotional sparing (i.e., reduction of the attentional impairment for words that are emotionally significant). However, deletion carriers demonstrated a further, more pronounced emotional sparing for negative targets. This finding demonstrates a contribution of genetics to individual differences in the emotional subjectivity of perception, which in turn may be linked to biases in later memory.

Tuesday, October 22, 2013

Silver Lining of a mind in the clouds

This post continues a MindBlog thread on the consequences of our minds being task-focused versus wandering. A seminal paper was Killingsworth and Gilbert's 2010 work "A Wandering Mind is an Unhappy Mind.", and I recently posted a more positive view. Franklin et al. now collect data of the sort Killingsworth and Gilbert used, but analyze with a bit more nuance:
The negative effects of mind-wandering on performance and mood have been widely documented. In a recent well-cited study, Killingsworth and Gilbert (2010) conducted a large experience sampling study revealing that all off-task episodes, regardless of content, have equal to or lower happiness ratings, than on-task episodes. We present data from a similarly implemented experience sampling study with additional mind-wandering content categories. Our results largely conform to those of the Killingsworth and Gilbert (2010) study, with mind-wandering generally being associated with a more negative mood. However, subsequent analyses reveal situations in which a more positive mood is reported after being off-task. Specifically when off-task episodes are rated for interest, the high interest episodes are associated with an increase in positive mood compared to all on-task episodes. These findings both identify a situation in which mind-wandering may have positive effects on mood, and suggest the possible benefits of encouraging individuals to shift their off-task musings to the topics they find most engaging.

Monday, October 21, 2013

Face recognition area of the brain also notes race and sex.

Hundreds of papers have been written on the fusiform face area (FFA) of our brains, which Contreras et al. now show immediately collects information about race and sex as well, showing patterns of activation that are different for black and white faces, and for female and male faces. Meaning is attached to those identifications later in visual processing. This specialization might have appeared for evolutionary or developmental reasons, for it can be important to know the sex and race of other people, especially in contexts in which those differences should change the way in which you interact with them. Here is their abstract:
Although prior research suggests that fusiform gyrus represents the sex and race of faces, it remains unclear whether fusiform face area (FFA)–the portion of fusiform gyrus that is functionally-defined by its preferential response to faces–contains such representations. Here, we used functional magnetic resonance imaging to evaluate whether FFA represents faces by sex and race. Participants were scanned while they categorized the sex and race of unfamiliar Black men, Black women, White men, and White women. Multivariate pattern analysis revealed that multivoxel patterns in FFA–but not other face-selective brain regions, other category-selective brain regions, or early visual cortex–differentiated faces by sex and race. Specifically, patterns of voxel-based responses were more similar between individuals of the same sex than between men and women, and between individuals of the same race than between Black and White individuals. By showing that FFA represents the sex and race of faces, this research contributes to our emerging understanding of how the human brain perceives individuals from two fundamental social categories.

Friday, October 18, 2013

Out of the group, out of control?

From Otten and Jonas:
The effects of social exclusion are far-reaching, both on an emotional and behavioral level. The present study investigates whether social exclusion also directly influences basic cognitive functions, specifically the ability to exert cognitive control. Participants were either excluded or included while playing an online game. To test whether exclusion altered cognitive control, we measured the electrophysiological responses to a Go/No Go task. In this task participants had to withhold a response (No Go) on a small number of trials while the predominant tendency was to make an overt (Go) response. Compared to Go trials the event-related potential evoked by No Go trials elicited an increased N2, reflecting the detection of the response conflict, followed by an increased P3, reflecting the inhibition of the predominant response. The N2 effect was larger for participants who had experienced exclusion, while the P3 effect was smaller. This indicates that exclusion leads to an increased ability to detect response conflicts, while at the same time exclusion decreases the neural processes that underlie the inhibition of unwanted behavior.

Thursday, October 17, 2013

Trashing Malcolm Gladwell

It is with some glee that I have been reading the many negative reviews of Malcolm Gladwell's most recent book (David and Goliath..), in particular Chad Orzel's "Malcolm Gladwell Is Deepak Chopra." He compares Gladwell's style to that of Deepak Chopra, who I immediately decided was a con-artist when I first encountered his work in the 1970s. After noting Gladwell's willful misleading of readers with cherry-picked science, Orzel notes the connection to Chopra:
So what does this have to do with everybody’s favorite bullshit artist stand-up Eastern philosopher? It occurred to me in reading some of the social media reactions that Gladwell stands in relation to good, responsible journalists in more or less the same position that Chopra stands in relation to actual quantum physicists. That is, he’s a glib and gifted writer who can talk just enough of the talk to buffalo people from outside the field. To a physicist, Chopra’s babble about “energy fields” and “congealing quantum soup” presents as utter gibberish, but he drops enough names and technical terms to sound superficially like somebody with real knowledge of physics, making it really hard for those of us who really know how the universe works to convince non-scientists that he doesn’t. If both sides throw around technical terms, but one twists them into a compelling narrative while the other is full of limits and caveats and, you know, math, well, the fact that the people with the complicated story are right doesn’t carry as much weight as it ought to.
A few further writeups are Poole's review relayed in The New Republic, and Chabris in Slate.

Wednesday, October 16, 2013

Constructive aspects of mind wandering

I've generally been noting research that documents some negative aspects of mind wandering, for example "A wandering mind is an unhappy mind" and "Better memory with less default mode activity." The other side of the coin, how day dreaming can be constructive, is developed by Kaufman here and here(PDF). He and his coauthors point out that the rewards of mind wandering:
...include self- awareness, creative incubation, improvisation and evaluation, memory consolidation, autobiographical planning, goal driven thought, future planning, retrieval of deeply personal memories, reflective consideration of the meaning of events and experiences, simulating the perspective of another person, evaluating the implications of self and others’ emotional reactions, moral reasoning, and reflective compassion
Kaufman argues for an definition of intelligence moves beyond emphasis on cognitive control, deliberate planning, and decontextualized problem solving, and that includes: individual’s personal goals, and considers both controlled forms of cognition (e.g., working memory, attentional focus, etc.) and spontaneous forms of cognition (e.g., intuition, affect, insight, implicit learning, latent inhibition, and the spontaneous triggering of episodic memories and declarative knowledge) are important potential contributors to that personal adaptation.

Tuesday, October 15, 2013

The changing psychology of culture from 1800 through 2000.

Greenfield makes use of the Google Books Ngram Viewer to observe a large shift from collectivist to individualist values during this period, as mass migration occurred from rural to urban areas. The corpus of books published in England and America was examined for the frequency of words like “obliged” and “choose”;“give” and “get”;“act” and “feel”, etc. Their abstract:
The Google Books Ngram Viewer allows researchers to quantify culture across centuries by searching millions of books. This tool was used to test theory-based predictions about implications of an urbanizing population for the psychology of culture. Adaptation to rural environments prioritizes social obligation and duty, giving to other people, social belonging, religion in everyday life, authority relations, and physical activity. Adaptation to urban environments requires more individualistic and materialistic values; such adaptation prioritizes choice, personal possessions, and child-centered socialization in order to foster the development of psychological mindedness and the unique self. The Google Ngram Viewer generated relative frequencies of words indexing these values from the years 1800 to 2000 in American English books. As urban populations increased and rural populations declined, word frequencies moved in the predicted directions. Books published in the United Kingdom replicated this pattern. The analysis established long-term relationships between ecological change and cultural change.

Monday, October 14, 2013

Distinctive brain correlates of brief compassion meditation.

This article by Hassenkamp provides a very useful integrative review of, and links to, several articles on brain correlates of mindfulness, empathy, and compassion meditation that I have noted separately in previous posts. It is becoming increasingly clear that even brief engagement with training or practice of compassion meditation enhances both perception of the emotional state of others and activity of the brain's networks related to love, affiliation, and positive emotion. Hassenkamp notes that the studies:
...highlight the important difference between merely having empathy, which can lead to negative emotions and even feelings of helplessness and burnout, versus compassion, which is rooted in loving, affiliative, positive feelings, and fosters a motivation to help. When faced with intense suffering, these findings could have major implications for strategies to overcome empathic distress and strengthen resilience, not to mention promoting helpful action.

Sunday, October 13, 2013

Is music the key to success?

I'm passing this on immediately after reading it. While I have done numerous posts on how music training influences brain development, for example to enhance and speed brain processing of complex inputs into complex motor outputs, this article by Joanne Lipman points to other straightforward reasons that musical training and continued practice as a adult correlates with high achievement, with high achievers noting qualities that: has sharpened: collaboration, creativity, discipline and the capacity to reconcile conflicting ideas. All are qualities notably absent from public life. Music may not make you a genius, or rich, or even a better person. But it helps train you to think differently, to process different points of view — and most important, to take pleasure in listening.

Friday, October 11, 2013

Oxytocin dilates our pupils and enhances emotion detection

Interesting work from Leknes et al.:
Sensing others’ emotions through subtle facial expressions is a highly important social skill. We investigated the effects of intranasal oxytocin treatment on the evaluation of explicit and ‘hidden’ emotional expressions and related the results to individual differences in sensitivity to others’ subtle expressions of anger and happiness. Forty healthy volunteers participated in this double-blind, placebo-controlled crossover study, which shows that a single dose of intranasal oxytocin (40 IU) enhanced or ‘sharpened’ evaluative processing of others’ positive and negative facial expression for both explicit and hidden emotional information. Our results point to mechanisms that could underpin oxytocin’s prosocial effects in humans. Importantly, individual differences in baseline emotional sensitivity predicted oxytocin’s effects on the ability to sense differences between faces with hidden emotional information. Participants with low emotional sensitivity showed greater oxytocin-induced improvement. These participants also showed larger task-related pupil dilation, suggesting that they also allocated the most attentional resources to the task. Overall, oxytocin treatment enhanced stimulus-induced pupil dilation, consistent with oxytocin enhancement of attention towards socially relevant stimuli. Since pupil dilation can be associated with increased attractiveness and approach behaviour, this effect could also represent a mechanism by which oxytocin increases human affiliation.

Wednesday, October 09, 2013

Our sense of fairness changes with weak electric stimulation of our prefrontal cortex.

Fascinating work from Ruff et al:
All known human societies have maintained social order by enforcing compliance with social norms. The biological mechanisms underlying norm compliance are, however, hardly understood. We show that the right lateral prefrontal cortex (rLPFC) is involved in both voluntary and sanction-induced norm compliance. Both types of compliance could be changed by varying neural excitability of this brain region with transcranial direct current stimulation, but they were affected in opposite ways, suggesting that the stimulated region plays a fundamentally different role in voluntary and sanction-based compliance. Brain stimulation had a particularly strong effect for compliance based on socially constituted sanctions, while it left beliefs about what the norm prescribes and about subjectively expected sanctions unaffected. Our findings suggest that rLPFC activity is a key biological prerequisite for an evolutionarily and socially important aspect of human behavior.
(Culotta does a brief review here.)

Tuesday, October 08, 2013

Psychedelic drugs cause cortical desynchronization

From Muthukumaraswamy et al., small wonder that it doesn't all hang together during the psychedelic experience:
Psychedelic drugs produce profound changes in consciousness, but the underlying neurobiological mechanisms for this remain unclear. Spontaneous and induced oscillatory activity was recorded in healthy human participants with magnetoencephalography after intravenous infusion of psilocybin—prodrug of the nonselective serotonin 2A receptor agonist and classic psychedelic psilocin. Psilocybin reduced spontaneous cortical oscillatory power from 1 to 50 Hz in posterior association cortices, and from 8 to 100 Hz in frontal association cortices. Large decreases in oscillatory power were seen in areas of the default-mode network. Independent component analysis was used to identify a number of resting-state networks, and activity in these was similarly decreased after psilocybin. Psilocybin had no effect on low-level visually induced and motor-induced gamma-band oscillations, suggesting that some basic elements of oscillatory brain activity are relatively preserved during the psychedelic experience. Dynamic causal modeling revealed that posterior cingulate cortex desynchronization can be explained by increased excitability of deep-layer pyramidal neurons, which are known to be rich in 5-HT2A receptors. These findings suggest that the subjective effects of psychedelics result from a desynchronization of ongoing oscillatory rhythms in the cortex, likely triggered by 5-HT2A receptor-mediated excitation of deep pyramidal cells.

Monday, October 07, 2013

Poulenc Improvisation No. 15

This piece is a homage to Edith Piaf.  The last of a series of Poulenc recordings I have done this year.


Better memory with less default mode activity

I've done a number of posts on our default mode versus attentional networks (a review is here, for example). Here is the summary and abstract for some interesting work in NeuroImage by Chai et al. on the relationship of these modes to memory:

-Children, adolescents and adults studied scenes during fMRI.
-Default-mode network (DMN) deactivation was examined during memory encoding.
-DMN deactivation was associated with successful memory encoding in adults.
-In children, deactivation of the DMN did not predict memory outcome. 
Task-induced deactivation of the default-mode network (DMN) has been associated in adults with successful episodic memory formation, possibly as a mechanism to focus allocation of mental resources for successful encoding of external stimuli. We investigated developmental changes of deactivation of the DMN (posterior cingulate, medial prefrontal, and bilateral lateral parietal cortices) during episodic memory formation in children, adolescents, and young adults (ages 8–24), who studied scenes during functional magnetic resonance imaging (fMRI). Recognition memory improved with age. We defined DMN regions of interest from a different sample of participants with the same age range, using resting-state fMRI. In adults, there was greater deactivation of the DMN for scenes that were later remembered than scenes that were later forgotten. In children, deactivation of the default-network did not differ reliably between scenes that were later remembered or forgotten. Adolescents exhibited a pattern of activation intermediate to that of children and adults. The hippocampal region, often considered part of the DMN, showed a functional dissociation with the rest of the DMN by exhibiting increased activation for later remembered than later forgotten scene that was similar across age groups. These findings suggest that development of memory ability from childhood through adulthood may involve increased deactivation of the neocortical DMN during learning.

Friday, October 04, 2013

Evilicious humans, hard-wired for war?

"Evilicious" is the title of a new book self published by Marc Hauser, the Harvard Psychologist forced to resign his position after it was discovered that he had been falsifying behavioral data to fit his foregone conclusions. He asks "why seemingly normal people torture, mutilate, and kill others for the fun of it — or for no apparent benefit at all." He suggests that humans uniquely evolved this capacity because "evildoers emerge when unsatisfied desires combine with the denial of reality, enabling individuals to engage in gratuitous cruelty toward innocent victims. This simple recipe is part of human nature, and part of our brain’s uniquely evolved capacity to combine different thoughts and emotions." Hauser's 'trying for a second chance' book has drawn a number of favorable reviews. One summary from Atran's review cited by Dobbs:
....“addiction to evil” – the persistent subjection of innocents to gratuitous cruelty — emerged as a by-product of the human brain’s unique evolutionary design. The ability to creatively combine all manner of thought and emotion enabled our species to produce great works of art and science, as well as to freely choose to kill and torture with a level of maliciousness unprecedented in the history of life on earth. Here we find that the most dangerous and effective evildoers are not sadists or serial killers with disordered minds, but mostly normal people who could have chosen not to kill and torture. When driven by unsatisfied desires — especially if channeled into dreams of glory for a cause — and in denying the reality and the humanity of others, even nice guys can become massively bloodthirsty.
A related issue is whether we are "hard-wired for war". Evolutionary biologist David Barash argues there is no convincing evidence for this. Despite examples such as Yanomamo ferocity, a broad survey shows that peacemaking is, if anything, more pronounced and widely distributed, especially among groups of nomadic foragers who are probably closest in ecological circumstance to our hominin ancestors.

Wednesday, October 02, 2013

Information sharing as a measure of brain consciousness

King et al. make measurements they suggest are a signature of conscious state in awake but noncommunicating patients. I pass on the summary, abstract, and one of their figures (and, the first graphic, thanks to Jean-Rémi King, who offers the unedited PDF of the article here):
 • Theories of consciousness link conscious access to global information integration
 • 181 EEG recordings were acquired, including 143 from VS and MCS patients
 • Information sharing across current sources was estimated with a new measure
 • The results suggest that unconscious patients have lower global information sharing

Neuronal theories of conscious access tentatively relate conscious perception to the integration and global broadcasting of information across distant cortical and thalamic areas. Experiments contrasting visible and invisible stimuli support this view and suggest that global neuronal communication may be detectable using scalp electroencephalography (EEG). However, whether global information sharing across brain areas also provides a specific signature of conscious state in awake but noncommunicating patients remains an active topic of research. We designed a novel measure termed “weighted symbolic mutual information” (wSMI) and applied it to 181 high-density EEG recordings of awake patients recovering from coma and diagnosed in various states of consciousness. The results demonstrate that this measure of information sharing systematically increases with consciousness state, particularly across distant sites. This effect sharply distinguishes patients in vegetative state (VS), minimally conscious state (MCS), and conscious state (CS) and is observed regardless of etiology and delay since insult. The present findings support distributed theories of conscious processing and open up the possibility of an automatic detection of conscious states, which may be particularly important for the diagnosis of awake but noncommunicating patients.

Figure - wSMI Increases with Consciousness, Primarily over Centroposterior Regions(A) The median wSMI that each EEG channel shares with all other channels is depicted for each state of consciousness.(B) 120 pairs formed by 16 clusters of EEG channels are depicted as 3D arcs whose height is proportional to the Euclidian distance separating the two clusters. Line color and thickness are proportional to the mean wSMI shared by the corresponding cluster pair.

Tuesday, October 01, 2013

Early emergence of mature brain alarm circuits in maternally deprived children

Many studies have shown adverse effects of various kinds of childhood deprivation or abuse, with maternal deprivation being one of the most significant. Normally, medial prefrontal cortex (mPFC) connections with the amygdala are immature during childhood and become adult-like during adolescence. Gee et al. show that institutionalized youths who experienced early maternal deprivation show mature connectivity at a much earlier age:
Early adversity has profound and lasting effects on neurodevelopment and emotional behavior. Under typical environmental conditions, prefrontal cortex connections with the amygdala are immature during childhood and become adult-like during adolescence. Rodent models show that maternal deprivation accelerates this development as an ontogenetic adaptation to adversity. Here, we demonstrate that, as in the rodent, children who experienced early maternal deprivation exhibit early emergence of mature amygdala–prefrontal connectivity. Evidence suggests that the adult-like neural phenotype, which is mediated by cortisol levels, confers some degree of enhanced emotion regulation, as maternally deprived youths with adult-like phenotypes are less anxious than their counterparts with immature phenotypes. Accelerated amygdala–prefrontal development may serve as an ontogenetic adaptation in the human in response to early adversity.