An awakening - recovery from coma by deep brain stimulation

You may well have seen accounts on this work in the press, but I thought I would excerpt from a description by Shadlen and Kiani that discusses possible underlying mechanisms of the case - in which stimulation of the thalamus of a man in a coma for six years after an accident restored consciousness.

A key component is the thalamus, which lies between the brainstem and the cerebral hemispheres, and forms the gateway to the brain's cortex. The thalamus is organized as a set of nuclei. The best understood of these nuclei are those containing the neurons that relay information from the eyes, ears and skin to the appropriate sensory cortex. But much of the thalamus is poorly understood. Anatomical studies in non-human primates have identified a class of thalamic neuron that might operate more generally in activating cortical networks6. These neurons, which stain positively for the calcium-binding protein calbindin, are found in all thalamic nuclei. Although we know little about the physiological properties of these calbindin-positive cells, they tend to exhibit a different pattern of connections with the cortex compared with the relay cells. Their axons terminate more broadly both across cortical areas and in layers that the relay cells miss. These calbindin-positive cells comprise a large percentage of the intralaminar nuclei of the thalamus — nuclei that have long been thought to have a role in arousal.

Schiff et al. hypothesized that their patient might express a minimal level of consciousness because of a primary impairment of the arousal system itself. The patient had suffered irreparable damage to much of the cerebral cortex, but many essential areas were preserved. By stimulating the intralaminar nuclei, the authors hoped to switch on the undamaged areas of cortex...The results were dramatic. Within 48 hours of the surgery to place the electrodes, the patient, who had remained in a minimally conscious state for 6 years, demonstrated increased arousal and sustained eye-opening, as well as rapid bilateral head-turning to voices.

The original article and the review then describe further recovery during a regime of varying patterns of brain stimulation. And here is an interesting summary of possible implications of this work:

...the observations ... may provide clues about the neurobiological underpinnings of consciousness. Cognitive neuroscience is beginning to expose the architecture of information processing that is directed towards goals and actions; we refer to this as an 'intentional framework', but it flies under various banners, including 'affordances' and 'embodied cognition...In essence, the brain does not process information in the abstract but instead consults information acquired through the senses and in memory insofar as it bears on the decisions made about potential actions and strategies. Our brains allow us to decide among possible options — that is, how and in what context to engage with the world around us. The brain makes many such decisions unconsciously. Indeed, the decision to engage at all is, in effect, an unconscious decision to be conscious. Thus, the brain of the sleeping mother queries the environment for the cry of her newborn. We suspect that the normal unconscious brain monitors the environment for cues that prompt it to decide whether to awaken and engage. This mechanism may be disrupted in various disorders of consciousness, including the minimally conscious state, hypersomnolence, concussion, abulia (lack of will) and possibly severe depression.

Previous theories of consciousness have relied on a central executive and magical physiological phenomena (for example, synchronized reverberations) to elevate the subconscious functions of the brain to consciousness. However, viewed as a decision to engage, consciousness can instead be studied in the same framework as other types of decision and the allocation of attention11. Rather than a central executive, there seems to be a network of brain regions that organize the resting state and maintain overall orientation towards context. It is quite possible that they make decisions about whether or not to engage and in what way. They do what Sartre considered impossible: they choose whether to choose or not.

How these networks relate to intralaminar nuclei or the matrix of calbindin-positive thalamic neurons is another question. However, the idea that these areas need to be turned on for consciousness leads us to wonder whether stimulation of the intralaminar thalamus in this patient worked through the activation of calbindin-positive neurons and these circuits.

Bonobo apes - human precursors as swingers?

The July 30 issue of "The New Yorker" has an engaging article by Ian Parker on bonobo apes, meant to be much nicer than chimpanzees, and perhaps the modern species most close to the evolutionary precursor of humans. Here are some clips from that article (PDF here).

In recent years, the bonobo has found a strange niche in the popular imagination, based largely on its reputation for peacefulness and promiscuity...This pop image of the bonobo—equal parts dolphin, Dalai Lama, and Warren Beatty—has flourished largely in the absence of the animal itself, which was recognized as a species less than a century ago. Two hundred or so bonobos are kept in captivity around the world.. It is one of the oddities of the bonobo world—and a source of frustration to some—that Frans de Waal, of Emory University, the high-profile Dutch primatologist and writer, who is the most frequently quoted authority on the species, has never seen a wild bonobo.

The article describes the field work of Gottfried Hohmann and his assistants, studying bonobo behavior in the wild. It turns out that a less flattering description of the species emerges. Aggression and infanticide have been observed, although not as prominently displayed as in Chimpanzees.

“It was so easy for Frans to charm everyone,” Hohmann said of de Waal one afternoon. “He had the big stories. We don’t have the big stories. Often, we have to say, ‘No, bonobos can be terribly boring. Watch a bonobo and there are days when you don’t see anything—just sleeping and eating and defecating. There’s no sex, there’s no food-sharing.’ ” During our first days in camp, the bonobos had been elusive. “Right now, bonobos are not vocalizing,” Hohmann said. “They’re just there. And if you go to a zoo, if you give them some food, there’s a frenzy. It’s so different.”...Captivity can have a striking impact on animal behavior. As Craig Stanford, a primatologist at the University of Southern California, recently put it, “Stuck together, bored out of their minds—what is there to do except eat and have sex?”

The media still regularly ask Frans de Waal about bonobos; and he still uses the species as a stick to beat what he scorns as “veneer theory”—the thought that human morality is no more than a veneer of restraint laid over a vicious, animal core. Some of his colleagues in primatology admit to impatience with his position—and with the broader bonobo cult that flattens a complex animal into a caricature of Edenic good humor. “Frans has got all the best intentions, in all sorts of ways, but there is this sense in which this polarizing of chimps and bonobos can be taken too far,” Richard Wrangham said. Hohmann concurred: “There are certainly some points where we are in agreement; and there are other points where I say, ‘No, Frans, you should go to Lomako or Lui Kotal, and watch bonobos, and then you’d know better.’ ” He went on, “Frans enjoyed the luxury of being able to say field work is senseless. When you see wild bonobos, some things that he has emphasized and stretched are much more modest; the sex stuff, for example. But other things are even more spectacular. He hasn’t seen meat-sharing, he has never seen hunting.”

Because of Hohmann’s disdain for premature theories, and his data-collecting earnestness, it had sometimes been possible to forget that he is still driving toward an eventual glimpse of the big picture—and that this picture includes human beings. Humans, chimpanzees, and bonobos share a common ancestor. Was this creature bonobo-like, as Hohmann suspects? Did the ancestral forest environment select for male docility, and did Homo and the chimpanzee then both dump that behavior, independently, as they evolved in less bountiful environments? The modern bonobo holds the answer, Hohmann said; in time, its behavior will start to illuminate such characteristics as relationships between men and women, the purpose of aggression, and the costs and benefits of male bonding.

Mind Control

I thought readers might get a chuckle from what the press is telling us about neuro-technology.

Cognitive scientists learn from magicians...

At the recent meeting of the Association for the Scientific Study of Consciousness that I attended in Las Vegas, one of most interesting sessions featured well known magicians. I was going to write this up, but here is a better job than I would do in a description of the session written by Martinez-Conde and Macknik (co-chairs of the meeting) in the July 26 issue of Nature Magazine:

Cognitive scientists take a lesson from magicians.

Teller, the mute half of the magician duo Penn & Teller, apparently pulls a coin out of thin air for the umpteenth time. The audience breaks into applause. It's another great performance in Las Vegas, Nevada — only tonight, Teller is part of a special symposium hosted by the Association for the Scientific Study of Consciousness, bringing together magicians and cognitive scientists.

Vision scientists have often turned to the visual arts to rediscover the principles underlying visual perception, such as how to convey the illusion of depth on a flat canvas. Similarly, cognitive scientists have much to learn from magicians, who have developed cognitive principles and illusions that trick audiences.

The Magic of Consciousness Symposium on 24 June attempted to plumb directly the depths of the intuition of world-class magicians. Magicians are behaviour experts who artfully manipulate attention and awareness. Their wealth of knowledge on cognition and behaviour is now ripe for picking.

James Randi — aka The Amaz!ng Randi — explained that spectators will easily accept unspoken assumptions. He made his point by fooling more than 200 consciousness researchers into thinking that his voice was being amplified by a dummy microphone, and by pretending to read with glasses that were merely empty frames.

Teller pulled coins out of thin air, conference bags and spectacles. He used water from his drinking glass to make a ball disappear. Shedding his normally silent stage persona, he described with eloquence how magicians make their audiences incorrectly link cause and effect. We all infer cause and effect in everyday life. When A precedes B, we conclude that A causes B. The skilled magician takes advantage of this inference by making sure that A (pouring water on a ball) always precedes B (the ball disappearing). However, A does not really cause B. The magician only makes it look so. Audiences assume that each repetition of a trick is done by the same method. "When a good magician repeats an effect, he varies the method in an unpredictable rhythm," said Teller. "That way, each time observers suspect one method, they find their suspicion disproven by the subsequent repetition." For instance, the disappearing ball is first secretly palmed by the other hand, but in the next repetition it is instead dropped on the magician's lap (allowing the magician to show that the other hand is empty).

Johnny Thompson — aka The Great Tomsoni — refers to this principle as "closing all the doors". That is, a good trick will appear to rule out all possible explanations, except for magic. Mac King illustrated these points by impossibly pulling a melon-sized rock out of his shoe — three times. The first two times he purposely used the same method, making it easier to see the trick the second time around. The third time he changed the method, deceiving the audience once again. "Much of our lives is devoted to understanding cause and effect," Teller said. "Magic provides a playground for those rational skills."

He also explained that "action is motion with a purpose". In normal social interactions, we constantly search for the purpose motivating other people's actions. An action with no obvious purpose raises questions. However, when the purpose seems crystal clear, we look no further. "Skilled magicians inform every necessary maneuver (motion) with a convincing intention," said Teller. Thus, the real purpose of the motion (hiding the ball) is hidden by the apparent purpose of the action (pouring the water).

Apollo Robbins, a professional thief who once pickpocketed Jimmy Carter's secret service detail, demonstrated the use of interpersonal distance and eye contact to control a target's gaze and attention. In doing so, he looted, undetected, every single pocket of a journalist from the audience.

James Randi tied the evening together by effortlessly escaping ropes knotted by philosopher Dan Dennett. The intuitive insights offered by magicians will frame future cognitive experiments, from measuring the dynamics of attentional blindness to determining the neural correlates of causal inference. Where in the brain is motion perceived as action? Does this same brain area encode the purpose of the action? For cognitive scientists, the second act of the show will take place in the lab.

Brain correlates of peer influence in adolescents

Grosbras et al. have explored neural correlates of inter-individual differences in the probability of resisting peer influence in early adolescence. Using functional magnetic resonance imaging, they found differences between 10-year-old children with high and low resistance to peer influence in brain activity during observation of angry hand movements and angry facial expressions. Compared with subjects with low resistance to peer influence, individuals with high resistance showed a highly coordinated brain activity in neural systems underlying perception of action and decision making: the right dorsal premotor cortex and the left dorsolateral prefrontal cortex. This suggests that resisting peer influence depends activities in these areas during observation of emotion-laden actions.

Release from helplessness and stress

A possible therapy from over-expressing a gene? From 'research highlights' in a recent issue of Nature, edited:

When mice experience recurrent, inescapable stress, some simply stop trying to get away. This behaviour, called 'learned helplessness', is relieved by antidepressants and is used to model depression and post-traumatic stress disorder.

It now appears that a protein called ΔFosB (a transcription factor that down regulates the substance P gene) may help mice to cope with repeated stress.

Eric Nestler of the University of Texas Southwestern Medical Center in Dallas and his colleagues (Berton et al. in Neuron) have found that ΔFosB is expressed by neurons that contain a pain-signalling peptide called substance P, in a brain region called the periaqueductal gray. Over-expressing ΔFosB in stressed mice diminishes stress-induced release of substance P, and reduces learned helplessness.

Effect of physical activity on cortical plasticity and brain function

I've done a number of posts relevant to the aging brain (effects of physical activity, etc., also see the blog category 'aging' in the left column). Kramer and Erickson offer a review "Capitalizing on cortical plasticity: influence of physical activity on cognition and brain function." (PDF here).

Given the aging populations in many countries throughout the world, there is an increasing interest in lifestyle factors and interventions that will enhance the cognitive vitality of older adults and reduce the risk for age-related neurological disorders, such as Alzheimer's disease. In this review, we evaluate the hypothesis that physical activity and exercise might serve to protect, and also enhance, cognitive and brain function across the adult lifespan. To this end, we critically review three separate literatures that have examined the influence of physical activity and exercise on cognition, brain function and brain structure of adults, including epidemiological or prospective observational studies, randomized human clinical interventions and non-human animal studies. We suggest that this literature supports the claim that physical activity enhances cognitive and brain function, and protects against the development of neurodegenerative diseases. We discuss future directions to address currently unresolved questions, such as interactions between multiple lifestyle factors on offsetting or protecting against cognitive and neural decline, and conclude that physical activity is an inexpensive treatment that could have substantial preventative and restorative properties for cognitive and brain function.

Who's Minding the Mind?

There is a great article with the title of this post by Benedict Carey in the July 31 NYTimes Science section (PDF here). It deals with a topics touched on by many posts in this blog: how our unconscious mind nudges our actions and decisions. The process is usually refered to as "priming." Here are a few clips from the article:

...study participants, college students, had no idea that their social instincts were being deliberately manipulated. On the way to the laboratory, they had bumped into a laboratory assistant, who was holding textbooks, a clipboard, papers and a cup of hot or iced coffee — and asked for a hand with the cup....That was all it took: The students who held a cup of iced coffee rated a hypothetical person they later read about as being much colder, less social and more selfish than did their fellow students, who had momentarily held a cup of hot java.

...people tidy up more thoroughly when there’s a faint tang of cleaning liquid in the air; they become more competitive if there’s a briefcase in sight, or more cooperative if they glimpse words like “dependable” and “support” — all without being aware of the change, or what prompted it.

The article mentions a study cited in a previous post here:

... a team of English and French neuroscientists performed brain imaging on 18 men and women who were playing a computer game for money. The players held a handgrip and were told that the tighter they squeezed when an image of money flashed on the screen, the more of the loot they could keep...As expected, the players squeezed harder when the image of a British pound flashed by than when the image of a penny did — regardless of whether they consciously perceived the pictures, many of which flew by subliminally. But the circuits activated in their brains were similar as well: an area called the ventral pallidum was particularly active whenever the participants responded...This area is located in what used to be called the reptilian brain, well below the conscious areas of the brain...The results suggest a “bottom-up” decision-making process, in which the ventral pallidum is part of a circuit that first weighs the reward and decides, then interacts with the higher-level, conscious regions later, if at all.

Scientists have spent years trying to pinpoint the exact neural regions that support conscious awareness, so far in vain. But there’s little doubt it involves the prefrontal cortex, the thin outer layer of brain tissue behind the forehead, and experiments like this one show that it can be one of the last neural areas to know when a decision is made...This bottom-up order makes sense from an evolutionary perspective. The subcortical areas of the brain evolved first and would have had to help individuals fight, flee and scavenge well before conscious, distinctly human layers were added later in evolutionary history. In this sense, unconscious goals can be seen as open-ended, adaptive agents acting on behalf of the broad, genetically encoded aims — automatic survival systems.

...the new research on priming makes it clear that we are not alone in our own consciousness. We have company, an invisible partner who has strong reactions about the world that don’t always agree with our own, but whose instincts, these studies clearly show, are at least as likely to be helpful, and attentive to others, as they are to be disruptive.

Brain damage and moral decision making

Moll and Oliveira-Souza (PDF here) do a nice review and discussion of experiments of a sort I have mentioned in an earlier post, that show that patients with ventromedial prefrontal cortex lesions are more likely to base moral decisions on utilitarian rather than emotional grounds. (The most extreme example comes from high conflict emotional scenarios such as the one in which one has to decide whether to push a bulky stranger onto the track of a runaway trolley to save the lives of five workmen, thus killing the stranger.)

Origins of social groups in infancy

Kinzler et al. report interesting observations on how language influences the selection of social groups by human infants.

What leads humans to divide the social world into groups, preferring their own group and disfavoring others? Experiments with infants and young children suggest these tendencies are based on predispositions that emerge early in life and depend, in part, on natural language. Young infants prefer to look at a person who previously spoke their native language. Older infants preferentially accept toys from native-language speakers, and preschool children preferentially select native-language speakers as friends. Variations in accent are sufficient to evoke these social preferences, which are observed in infants before they produce or comprehend speech and are exhibited by children even when they comprehend the foreign-accented speech. Early-developing preferences for native-language speakers may serve as a foundation for later-developing preferences and conflicts among social groups.

And here is the fascinating introduction to the article, whose PDF version can be obtained here.

The Gileadites captured the fords of the Jordan leading to Ephraim, and whenever a survivour of Ephraim said, "Let me go over," the men of Gilead asked him, "Are you an Ephraimite?" If he replied, "No," they said, "All right, say ‘Shibboleth’." If he said, "Sibboleth," because he could not pronounce the word correctly, they seized him and killed him at the fords of the Jordan. Forty-two thousand Ephraimites were killed at that time.

Judges 12:5–6.

The biblical story of Shibboleth speaks of the ancient massacre of those who could not correctly pronounce a phrase, thereby revealing their out-group status. Modern-day Shibboleth is ubiquitous: United States history alone abounds with examples of linguistic discrimination, from the severing of the tongues of slaves who spoke no English, to the forbidding of the public speaking of German during World War II and the execution of Russian speakers after the Alaskan purchase (1). Recent world history provides examples of linguicide paired with genocide of the Kurds in Turkey (2) and of imposed language policies initiating anti-Apartheid riots in South Africa (3). Favor for one's native language group pervades contemporary politics in more subtle ways as well, for example, in recent debates concerning bilingual education, the politics of sign languages in deaf education, or proposals to make English the national language of the United States. We present evidence that the connection between language and human social groups has roots in human infancy, where it guides early-developing social preferences and predisposes humans to interact with members of their own linguistic group.

Interactions between native and second languages in the brain

It is known from fMRI imaging studies that second languages can recruit brain areas not activated by the native language, and damage to these areas caused by strokes can compromise one language more than the other. Theirry and Wu now show that unconscious interaction and translation occurs between the two systems:

Whether the native language of bilingual individuals is active during second-language comprehension is the subject of lively debate. Studies of bilingualism have often used a mix of first- and second-language words, thereby creating an artificial "dual-language" context. Here, using event-related brain potentials, we demonstrate implicit access to the first language when bilinguals read words exclusively in their second language. Chinese–English bilinguals were required to decide whether English words presented in pairs were related in meaning or not; they were unaware of the fact that half of the words concealed a character repetition when translated into Chinese. Whereas the hidden factor failed to affect behavioral performance, it significantly modulated brain potentials in the expected direction, establishing that English words were automatically and unconsciously translated into Chinese. Critically, the same modulation was found in Chinese monolinguals reading the same words in Chinese, i.e., when Chinese character repetition was evident. Finally, we replicated this pattern of results in the auditory modality by using a listening comprehension task. These findings demonstrate that native-language activation is an unconscious correlate of second-language comprehension.

What drives evolution - natural selection or mutations?

Here is another perspective article, from Masotoshi Nei (PDE here), on what may be a paradigm shift in evolutionary theory.

Recent studies of developmental biology have shown that the genes controlling phenotypic characters expressed in the early stage of development are highly conserved and that recent evolutionary changes have occurred primarily in the characters expressed in later stages of development. Even the genes controlling the latter characters are generally conserved, but there is a large component of neutral or nearly neutral genetic variation within and between closely related species. Phenotypic evolution occurs primarily by mutation of genes that interact with one another in the developmental process. The enormous amount of phenotypic diversity among different phyla or classes of organisms is a product of accumulation of novel mutations and their conservation that have facilitated adaptation to different environments. Novel mutations may be incorporated into the genome by natural selection (elimination of preexisting genotypes) or by random processes such as genetic and genomic drift. However, once the mutations are incorporated into the genome, they may generate developmental constraints that will affect the future direction of phenotypic evolution. It appears that the driving force of phenotypic evolution is mutation, and natural selection is of secondary importance.

Neural correlates of understanding concrete versus abstract words

Pexman et al. have used functional MRI to evaluate several different theories of semantic (meaning) representation that attempt to explain why concrete words (CARROT) are recognized and remembered more readily than abstract words (TRUTH). Clips from their abstract:

This concreteness effect has historically been explained by two theories of semantic representation: dual-coding...and context-availability. Past efforts to adjudicate between these theories using functional magnetic resonance imaging have produced mixed results. Using event-related functional magnetic resonance imaging, we reexamined this issue with a semantic categorization task that allowed for uniform semantic judgments of concrete and abstract words. The participants were 20 healthy adults. Functional analyses contrasted activation associated with concrete and abstract meanings of ambiguous and unambiguous words. Results showed that for both ambiguous and unambiguous words, abstract meanings were associated with more widespread cortical activation than concrete meanings in numerous regions associated with semantic processing, including temporal, parietal, and frontal cortices. These results are inconsistent with both dual-coding and context-availability theories, as these theories propose that the representations of abstract concepts are relatively impoverished. Our results suggest, instead, that semantic retrieval of abstract concepts involves a network of association areas. We argue that this finding is compatible with a theory of semantic representation such as Barsalou's perceptual symbol systems, whereby concrete and abstract concepts are represented by similar mechanisms but with differences in focal content.

The genuine problem of consciousness

Jack, Robbins, and Roepstorff suggest (PDF here) that:

...popular conceptions of the problem of consciousness, epitomized by David Chalmers' formulation of the 'hard problem', can be best explained as a cognitive illusion, which arises as a by-product of our cognitive architecture. We present evidence from numerous sources to support our claim that we have a specialized system for thinking about phenomenal states, and that an inhibitory relationship exists between this system and the system we use to think about physical mechanisms.

The genuine problem of consciousness is a problem about explanation, but it isn’t the sort of problem that can be solved by a theory of consciousness. We have two different ways of understanding the mind: we can understand it as a physical mechanism, and we can understand it from a personal perspective. The problem is that contemporary scientific psychology aims almost exclusively at mechanistic explanations of the mind. This is, ironically, no less true of most supposed scientific theories of consciousness than it is of the regular business of experimental psychology and cognitive neuroscience. Yet, for reasons both intellectual and practical, mechanistic explanation is not enough on its own. We can’t understand the mind unless we can understand it for ourselves, from our own personal-level perspective. If we are right that physical and phenomenal concepts belong to fundamentally distinct networks, then it is a problem that may never be definitively resolved. Nonetheless, it is a problem we can make progress on, for even if these networks always remain distinct, they can still be integrated into a more coherent whole. The genuine problem of consciousness is the challenge of achieving this largescale integration of our conceptual scheme.

See Jack's website for responses to and commentaries on this paper.

Paradoxes Of Our Age

I don't usually inflict homilies on my readers, but I pass on these brief lines found while cruising the web, attributed to the 14th Dali Lama.

We have bigger houses but smaller families;

More conveniences, but less time.

We have more degrees but less sense.

More knowledge but less judgment.

More experts, but more problems.

More medicines but less healthiness.

We’ve been all the way to the moon and back, but have trouble in crossing the street to meet our new neighbor.

We build more computers to hold more copies than ever, but have less real communication;

We have become long on quantity, but short on quality.

These are times of fast foods but slow digestion.

Tall men but short characters.

Steep profits but shallow relationships.

It’s a time when there is much in the window, but nothing in the room.

Our baseline brain activity alters conscious perception

Our perceptions of weak somatosensory (touching) stimuli can vary widely. Boly et al. (PDF here) ask whether variability in perception of identical stimuli relates to differences in prestimulus, baseline brain activity. Here is their abstract, followed by one figure from their paper:

In perceptual experiments, within-individual fluctuations in perception are observed across multiple presentations of the same stimuli, a phenomenon that remains only partially understood. Here, by means of thulium–yttrium/aluminum–garnet laser and event-related functional MRI, we tested whether variability in perception of identical stimuli relates to differences in prestimulus, baseline brain activity. Results indicate a positive relationship between conscious perception of low-intensity somatosensory stimuli and immediately preceding levels of baseline activity in medial thalamus and the lateral frontoparietal network, respectively, which are thought to relate to vigilance and "external monitoring." Conversely, there was a negative correlation between subsequent reporting of conscious perception and baseline activity in a set of regions encompassing posterior cingulate/precuneus and temporoparietal cortices, possibly relating to introspection and self-oriented processes. At nociceptive levels of stimulation, pain-intensity ratings positively correlated with baseline fluctuations in anterior cingulate cortex in an area known to be involved in the affective dimension of pain. These results suggest that baseline brain-activity fluctuations may profoundly modify our conscious perception of the external world.

Neural correlates of somatosensory stimuli awareness. Consciously perceived stimuli compared with unperceived intensity-matched stimuli were associated with greater activity in bilateral dorsolateral prefrontal (DLPF) and intraparietal sulcus/posterior parietal cortex (IPS) activity (yellow-red sections) (A) and less activity in a network encompassing bilateral posterior cingulate precuneas (Pr), mesiofrontal cortices (MF), temporoparietal junctions (TP), right inferior temporal (IT), and left superior frontal gyri (SF) (blue sections) (B).

Obesity as contagion

Here are some clips from a rather fascinating article by Kolata in the NYTimes. We know that moods are like viruses, contagious - one happy person can lift the mood of the group they are in, one depressed person can do the opposite. Such a process appears to operate on a much longer time scale with respect to body mass. (By the way, I draft this post on Wednesday afternoon and later at happy hour at Genna's bar on Capitol square in Madison, I look up at the NBC evening news to find the material featured there. The marketing of sexy new findings moves very fast).

The Framingham study involved a detailed analysis of a large social network of 12,067 people who had been closely followed for 32 years, from 1971 until 2003. The investigators knew who was friends with whom, as well as who was a spouse or sibling or neighbor, and they knew how much each person weighed at various times over three decades. That let them examine what happened over the years as some individuals became obese. Did their friends also become obese? Did family members or neighbors?...The answer, the researchers report, was that people were most likely to become obese when a friend became obese. That increased a person’s chances of becoming obese by 57 percent....Proximity did not seem to matter: the influence of the friend remained even if the friend was hundreds of miles away. And the greatest influence of all was between mutual close friends. There, if one became obese, the odds of the other becoming obese were nearly tripled...You change your idea of what is an acceptable body type by looking at the people around you.

fMRI of "Love"

Wow, count on some scientists to take all the titilation out of it with a title like:
"The Neural Basis of Love as a Subliminal Prime: An Event-related Functional Magnetic Resonance Imaging Study." Here is the abstract from Ortigue et al.:

Throughout the ages, love has been defined as a motivated and goal-directed mechanism with explicit and implicit mechanisms. Recent evidence demonstrated that the explicit representation of love recruits subcorticocortical pathways mediating reward, emotion, and motivation systems. However, the neural basis of the implicit (unconscious) representation of love remains unknown. To assess this question, we combined event-related functional magnetic resonance imaging (fMRI) with a behavioral subliminal priming paradigm embedded in a lexical decision task. In this task, the name of either a beloved partner, a neutral friend, or a passionate hobby was subliminally presented before a target stimulus (word, nonword, or blank), and participants were required to decide if the target was a word or not. Behavioral results showed that subliminal presentation of either a beloved's name (love prime) or a passion descriptor (passion prime) enhanced reaction times in a similar fashion. Subliminal presentation of a friend's name (friend prime) did not show any beneficial effects. Functional results showed that subliminal priming with a beloved's name (as opposed to either a friend's name or a passion descriptor) specifically recruited brain areas involved in abstract representations of others and the self, in addition to motivation circuits shared with other sources of passion. More precisely, love primes recruited the fusiform and angular gyri. Our findings suggest that love, as a subliminal prime, involves a specific neural network that surpasses a dopaminergic–motivation system.

Coordinated eye movements during dialog.

A commentary on an interesting article by Richardson et al. which illustrates yet again the social synchrony of our brains. See also this PsyBlog link on our nonverbal symphony and synchrony of interactions, as well as this previous post on an EEG signal that reflects social coordination. Or, this link on social context reflected at the level of single cell recordings in the monkey parietal cortex.

A dialogue, though generally understood to be a conversation between two people, allows for much more than the mere exchange of verbal information. Linguistic (for example, syntax) and nonlinguistic (for example, body postures) tell-tales develop and become synchronized as people talk and listen. Visual attention is another dimension in which behavior can become coordinated as when a listener's gaze is directed toward an object of mutual interest by pointing.

Richardson et al. show that the eyes of conversants--who are looking at the same scene but are not within sight of each other--tracked the same objects within the scene for several seconds, starting from the time at which the speaker began to fixate on the object before talking about it and including the time taken by the listener to saccade to the object after hearing what the speaker had begun to say. Another important contribution to the coordination of visual attention comes from having a common ground of understanding. Conversants looking at a Salvador Dalí painting were more likely to exhibit synchronized eye movements if they had previously heard the same introduction, either to the painting itself or to Dalí's life, as compared to pairs of conversants in which one had heard about the painting and the other about his life.

Neuroeconomics - a site to browse

I thought I would point you to the website of Read Montaque's Human Neuroimaging Laboratory at Baylor University. He is is guy whose work on behavioral preference for culturally familiar drinks is credited with a large part of the responsibility for the current neuromarketing craze. A new direction is the hyperscanning method by which multiple subjects, each in a separate MRI scanner, can interact with one another while their brains are simultaneously scanned. This permits study of the brain responses that underlie important social interactions.