Friday, September 30, 2011

There is nothing paranormal about near-death experiences.

Mobbs and Watt argue that neuroscience can explain seeing bright lights, meeting the dead, or being convinced you are one of them, suggesting that there is nothing paranormal about these experiences. Instead, near-death experiences are the manifestation of normal brain function gone awry, during a traumatic, and sometimes harmless, event. They engage several basic features of near death experiences (awareness of being dead, out of body experiences, tunnel of light, meeting deceased people, euphoric emotions) and note the brain regions whose perturbation by electrical stimulation or ischemic strokes can induce each phenomenon. Some can be observed in normal individuals under particular conditions of sensory stimulation (I've done posts on the Blanke experiments on out of body experiences). Their arguments are of the "may be" or "could be" sort, and their summary seems to to be particularly vague hand waving...

The near-death experience is a complex set of phenomena and a single account will not capture all its components. One recent theory is that the basic arousal systems beginning in the midbrain may account for many of the components of the near-death experience. Of interest is the locus coeruleus, a midbrain region involved in the release of noradrenaline. Noradrenaline is known to be involved in arousal related to fear, stress, and hypercarbia, and is highly connected to regions that mediate emotion and memory, including the amygdala and hippocampus. Indeed, stimulation of the noradrenaline system has been shown to enhance and consolidate memory, and plays a critical role in the sleep-wake cycle, including REM sleep. Along with basic midbrain systems, such as the periaqueductal gray, a region involved in opioid analgesia and basic fear responses, and the ventral tegmental area, which is a core dopamine reward area, the noradrenaline system may be part of a basic set of systems that directly or indirectly evoke positive emotions, hallucinations and other features of the near-death experience.

Taken together, the scientific evidence suggests that all aspects of the near-death experience have a neurophysiological or psychological basis: the vivid pleasure frequently experienced in near-death experiences may be the result of fear-elicited opioid release, while the life review and REM components of the near-death experience could be attributed to the action of the locus coeruleus- noradrenaline system. Out-of-body experiences and feelings of disconnection with the physical body could arise because of a breakdown in multisensory processes, and the bright lights and tunneling could be the result of a peripheral to fovea breakdown of the visual system through oxygen deprivation. A priori expectations, where the individual makes sense of the situation by believing they will experience the archetypal near-death experience package, may also play a crucial role. If one challenge of science is to demystify the world, then research should begin to test these and other hypotheses. Only then will discussion of near-death experiences move beyond theological dialogue and into the lawful realm of empirical neurobiology.

Longevity gene debate.

A collaboration between German, French, and British laboratories is challenging the basic observations on extending life span in nematodes and fruitflies, made in American laboraties, that started off the excitement about resveratrol (in red wine) and the sirtuin genes. From Wade's review:

Both experiments were flawed, they say, because the worms and flies used as a control were not genetically identical to the test organisms. The London researchers report that they have repeated the experiments with proper controls and found that extra sirtuin does not, after all, make the worms or flies live longer.

Thursday, September 29, 2011

Yoghurt lowers stress in the brain.

Here is a totally fascinating study done at the University College Cork indicating that the presence of probiotic bacteria in the gut can result in lower stress in the brain (via a pathway involving the vagus nerve and the brain neurotransmitter GABA). Perhaps that’s one reason for the longevity observed in many yogurt-eating populations. Their

...findings highlight the important role of bacteria in the bidirectional communication of the gut–brain axis and suggest that certain organisms may prove to be useful therapeutic adjuncts in stress-related disorders such as anxiety and depression.
I've started having organic yoghurt with mixes of different probiotic bacteria such as the Lactobacillus mentioned below for lunch (not the usual supermarket stuff larded with high fructose corn syrup), and of course am feeling more calm already (placebo effect, anyone?). Here is the whole abstract that notes the brain chemistry involved:
There is increasing, but largely indirect, evidence pointing to an effect of commensal gut microbiota on the central nervous system (CNS). However, it is unknown whether lactic acid bacteria such as Lactobacillus rhamnosus could have a direct effect on neurotransmitter receptors in the CNS in normal, healthy animals. GABA is the main CNS inhibitory neurotransmitter and is significantly involved in regulating many physiological and psychological processes. Alterations in central GABA receptor expression are implicated in the pathogenesis of anxiety and depression, which are highly comorbid with functional bowel disorders. In this work, we show that chronic treatment with L. rhamnosus (JB-1) induced region-dependent alterations in GABAB1b mRNA in the brain with increases in cortical regions (cingulate and prelimbic) and concomitant reductions in expression in the hippocampus, amygdala, and locus coeruleus, in comparison with control-fed mice. In addition, L. rhamnosus (JB-1) reduced GABAAα2 mRNA expression in the prefrontal cortex and amygdala, but increased GABAAα2 in the hippocampus. Importantly, L. rhamnosus (JB-1) reduced stress-induced corticosterone and anxiety- and depression-related behavior. Moreover, the neurochemical and behavioral effects were not found in vagotomized mice, identifying the vagus as a major modulatory constitutive communication pathway between the bacteria exposed to the gut and the brain. Together, these findings highlight the important role of bacteria in the bidirectional communication of the gut–brain axis and suggest that certain organisms may prove to be useful therapeutic adjuncts in stress-related disorders such as anxiety and depression.

Wednesday, September 28, 2011

Infidelity yields better offspring

Here is a study of birds (dark-eyed juncos) who form a social pair with one partner but produce more than one-quarter of their offspring from extra-pair matings. These young go on to reproduce more successfully than those sired within the social pair. (I could wonder if this is relevant to us humans.)

In many species, each female pairs with a single male for the purpose of rearing offspring, but may also engage in extra-pair copulations. Despite the prevalence of such promiscuity, whether and how multiple mating benefits females remains an open question. Multiple mating is typically thought to be favoured primarily through indirect benefits (i.e. heritable effects on the fitness of offspring). This prediction has been repeatedly tested in a variety of species, but the evidence has been equivocal, perhaps because such studies have focused on pre-reproductive survival rather than lifetime fitness of offspring. Here, we show that in a songbird, the dark-eyed junco (Junco hyemalis), both male and female offspring produced by extra-pair fertilizations have higher lifetime reproductive success than do offspring sired within the social pair. Furthermore, adult male offspring sired via extra-pair matings are more likely to sire extra-pair offspring (EPO) themselves, suggesting that fitness benefits to males accrue primarily through enhanced mating success. By contrast, female EPO benefited primarily through enhanced fecundity. Our results provide strong support for the hypothesis that the evolution of extra-pair mating by females is favored by indirect benefits and shows that such benefits accrue much later in the offspring's life than previously documented.

Tuesday, September 27, 2011

Atul Gawande on improving skilled performance by coaching

Anything Gawande writes is worth reading. I have previously noted his essays on aging and medical practice. In his most recent New Yorker essay, he discusses how expert coaching is used in many fields, and describes his own experience with recruiting a senior surgeon to improve his own experience as a surgeon.

The Buddha's Biology

I had started to occasionally re-post an old post that really struck me during my scan of this blog since its beginning in 2006, and now repeat the following old post, having come upon it for a second time:

I want to mention a book by that I have found to be a useful summary and distillation of correspondences between classical Buddhist psychology and modern psychology and evolutionary biology. Don't let its self-helpy new-agey title put you off (Buddha's Nature: A Practical Guide to Discovering Your Place in the Cosmos). It's by a crazy guy named Wes Nisker, a stand up Buddhist comic and veteran of the sixties and seventies new age San Francisco scene whose other writings include "The Big Bang, The Buddha, and the Baby Boom" and "The Essential Crazy Wisdom". It is a largely accurate descriptions of how Buddhism's four foundations of mindfulness can be taken to correspond to the bottom-up construction of our nervous system and consciousness, and to stages in the evolution of our nervous systems.

Sensing or exploring the nature of our elemental physical existence, our body breathing and homeostasis, is a focus of the Buddha's First Foundation of Mindfulness. This first foundation corresponds to physical elements of the body and homeostasis (regulation of blood flow, body temperature, etc.) These functions center in primitive brain stem structures we share with reptiles and other vertebrates. This core regulates interactions with the physical world elemental to having a self that we seldom think about - like breathing, supporting ourselves against gravity, seeing, tasting, smelling, touching, hearing.

These core structures also regulate our urge to remedy hunger, to have sex, to approach or avoid, to flee or fight when suddenly presented with very threatening situations. Our experience of these primary and instinctual basic drives, in its urgency and automaticity, has a very different quality than our experience of thoughts or more complicated emotions. The Buddha's Second Foundation of Mindfulness rests on the sentience of the nervous system which can note these elemental feelings, impressions of pleasant/unpleasant/neutral/painful, etc. We can, in more quiet moments of reflection or meditation note the more muted `flickers' of these primal forces, appearing and disappearing almost as transient quantal energies.

Our human introspective access to, observation of, emotional feelings more nuanced than the basic drives mentioned above is the focus of the Buddha's third foundation of mindfulness (affection, fear, anger, sadness, playfulness, etc.). These are regulated by a new kind of cortex that appears in mammals between the brain stem and the outer layer of the cortex, usually referred to as the limbic system.

Finally, our higher level cognitive abilities associated with the newer cortex (neocortex) that forms the top layers or our brain - our ability to note how thoughts and feelings are produced, as natural occurrences like breathing or the heartbeat - are a focus of the Buddha's fourth foundation of mindfulness.

Nisker's book has several sections of exercises or meditations useful in sensing layers of the self, its evolutionary nature, and its symbiosis with the external social and physical world.

Monday, September 26, 2011

Delayed gratification - 40 years later.

Casey et al. (open access) do a followup of the famous "marshmallow experiments" that showed young children who are better at delaying gratification to obtain a greater reward do better latter in life. They were able to test 60 individuals from the original study, now in their mid-40s, and in a subset of these were able to demonstrate stable differences in frontostriatal circuitries that integrate motivational and control processes in low delayers versus high delayers.

We examined the neural basis of self-regulation in individuals from a cohort of preschoolers who performed the delay-of-gratification task 4 decades ago. Nearly 60 individuals, now in their mid-forties, were tested on “hot” and “cool” versions of a go/nogo task to assess whether delay of gratification in childhood predicts impulse control abilities and sensitivity to alluring cues (happy faces). Individuals who were less able to delay gratification in preschool and consistently showed low self-control abilities in their twenties and thirties performed more poorly than did high delayers when having to suppress a response to a happy face but not to a neutral or fearful face. This finding suggests that sensitivity to environmental hot cues plays a significant role in individuals’ ability to suppress actions toward such stimuli. A subset of these participants (n = 26) underwent functional imaging for the first time to test for biased recruitment of frontostriatal circuitry when required to suppress responses to alluring cues. Whereas the prefrontal cortex differentiated between nogo and go trials to a greater extent in high delayers, the ventral striatum showed exaggerated recruitment in low delayers. Thus, resistance to temptation as measured originally by the delay-of-gratification task is a relatively stable individual difference that predicts reliable biases in frontostriatal circuitries that integrate motivational and control processes.

Friday, September 23, 2011

Nurture affects gender differences in spatial abilities

Here is a fascinating bit from Hoffman et al.:

Women remain significantly underrepresented in the science, engineering, and technology workforce. Some have argued that spatial ability differences, which represent the most persistent gender differences in the cognitive literature, are partly responsible for this gap. The underlying forces at work shaping the observed spatial ability differences revolve naturally around the relative roles of nature and nurture. Although these forces remain among the most hotly debated in all of the sciences, the evidence for nurture is tenuous, because it is difficult to compare gender differences among biologically similar groups with distinct nurture. In this study, we use a large-scale incentivized experiment with nearly 1,300 participants to show that the gender gap in spatial abilities, measured by time to solve a puzzle, disappears when we move from a patrilineal society to an adjoining matrilineal society. We also show that about one-third of the effect can be explained by differences in education. Given that none of our participants have experience with puzzle solving and that villagers from both societies have the same means of subsistence and shared genetic background, we argue that these results show the role of nurture in the gender gap in cognitive abilities.

Thursday, September 22, 2011

Testosterone modulates brain talk in social emotional behavior.

People with higher testosterone levels show more approach-related behavior during short social exchanges, and recent work has shown that this hormone influences activity of the amygdala (central to emotional behavior) and the ventral lateral (VLPFC) and orbital frontal (OFC) prefrontal areas of our cortex. I'm passing on this link to an open access article by Volman et al. that details experiments showing that testosterone modulates the effective connectivity between amygdala and VLPFC in approach-avoidance behavior. Their results indicate that endogenous testosterone influences local prefrontal activity and interregional connectivity supporting the control of social emotional behavior.

Wednesday, September 21, 2011

Evolutionary rationale for positive illusions.

Johnson and Fowler offer a fascinating explanation for why 70% of us (and 90% of college professors) feel we are above average in physical skills, intelligence, leadership, importance to our groups, driving skills, healthiness of our behavior, etc. etc. The authors make the striking suggestion that biased self-beliefs can actually lead people to make the right decision, whereas unbiased self-images would lead to a suboptimal decision. In their model overconfident populations are evolutionarily stable over a more wide range of environments than realistic populations, and they suggest this "may help to explain why overconfidence remains prevalent today, even if it contributes to hubris, market bubbles, financial collapses, policy failures, disasters and costly wars." Here is their abstract:

Confidence is an essential ingredient of success in a wide range of domains ranging from job performance and mental health to sports, business and combat. Some authors have suggested that not just confidence but overconfidence—believing you are better than you are in reality—is advantageous because it serves to increase ambition, morale, resolve, persistence or the credibility of bluffing, generating a self-fulfilling prophecy in which exaggerated confidence actually increases the probability of success. However, overconfidence also leads to faulty assessments, unrealistic expectations and hazardous decisions, so it remains a puzzle how such a false belief could evolve or remain stable in a population of competing strategies that include accurate, unbiased beliefs. Here we present an evolutionary model showing that, counterintuitively, overconfidence maximizes individual fitness and populations tend to become overconfident, as long as benefits from contested resources are sufficiently large compared with the cost of competition. In contrast, unbiased strategies are only stable under limited conditions. The fact that overconfident populations are evolutionarily stable in a wide range of environments may help to explain why overconfidence remains prevalent today, even if it contributes to hubris, market bubbles, financial collapses, policy failures, disasters and costly wars.

Tuesday, September 20, 2011

Rewriting self-fulfilling prophecies about social rejection

Stinson et al. provide yet another example of how even a very modest intervention to alter self-image can have long lasting effects:

Chronically insecure individuals often behave in ways that result in the very social rejection that they most fear. We predicted that this typical self-fulfilling prophecy is not immutable. Self-affirmation may improve insecure individuals’ relational security, and this improvement may allow them to express more welcoming social behavior. In a longitudinal experiment, a 15-min self-affirmation improved both the relational security and experimenter-rated social behavior of insecure participants up to 4 weeks after the initial intervention. Moreover, the extent to which self-affirmation improved insecure participants’ relational security at 4 weeks predicted additional improvements in social behavior another 4 weeks after that. Our finding that insecure participants continued to reap the social benefits of self-affirmation up to 8 weeks after the initial intervention demonstrates that it is indeed possible to rewrite the self-fulfilling prophecy of social rejection.
The experiment used the usual gaggle of psychology undergraduates. After answering a relational security questionaire,
Participants were assigned to one of two conditions, in both of which they ranked 11 values (e.g., academics) according to personal importance. Participants in the self-affirmation condition were instructed to write several paragraphs describing why their top-ranked value was important to them. They then listed the top two reasons why they picked that value as most important and indicated the extent to which their top-ranked value influenced their lives and was an important part of their self-image. Participants in the control condition were also instructed to write several paragraphs and answer similar questions, except that we asked this group to focus on their ninth-ranked value and why it might be important to someone else.

Monday, September 19, 2011

Musical expertise boosts language perception

Perhaps the thousands of hours I have put in on piano practice have made it easier for me to write? A few clips from the introduction of Francois and Schön :

The fact that musicians perceive some sound features more accurately than nonmusicians do is not so surprising. After all, they spend hours and hours of their life focusing on sounds and the way they are generated, paying particular attention to pitch, timber, duration, and timing. However, what seems less evident to us is whether or not this intensive musical practice can affect nonmusical abilities. Several recent studies seem to confirm this possibility….In this study, we took the challenge of focusing on a rather high cognitive function: word segmentation, namely, the ability to extract words from continuous speech…Participants listened to an artificial sung language (wherein music and language dimensions are highly intertwined) and were then tested with a 2-alternative forced-choice task on pairs of words and melodies (familiar vs. unfamiliar). The main goal of this study was to test whether musical expertise can facilitate word segmentation. With this aim, we compared 2 groups, one group with formal musical training and one without.
And here is their abstract:
Musical training is known to modify auditory perception and related cortical organization. Here, we show that these modifications may extend to higher cognitive functions and generalize to processing of speech. Previous studies have shown that adults and newborns can segment a continuous stream of linguistic and nonlinguistic stimuli based only on probabilities of occurrence between adjacent syllables or tones. In the present experiment, we used an artificial (sung) language learning design coupled with an electrophysiological approach. While behavioral results were not clear cut in showing an effect of expertise, Event-Related Potentials data showed that musicians learned better than did nonmusicians both musical and linguistic structures of the sung language. We discuss these findings in terms of practice-related changes in auditory processing, stream segmentation, and memory processes.

Friday, September 16, 2011

Neural correlates of pain reduction through meditation

Salomons and Kucyi present a nice review of experiments examining meditation and pain reduction (PDF here).

...A cognitive mechanism that is thought to be unique to mindfulness is the combination of increased attention and reduced negative evaluation...the key to reported analgesic effects of meditation training might be the co-occurring reduction in emotional and evaluative responses. Thus it is noteworthy that [several experiments] found activation patterns in regions associated with downregulation of negative affective responses, and functional decoupling of dorso-lateral prefrontal cortex and cingulate...attributed to dissociation between attention to pain and evaluation of pain. Zeidan and colleagues noted an inverse correlation between OFC activation and unpleasantness ratings, which was attributed to altered processing of reward and hedonic experiences. The degree of concordance between these studies suggests that meditative practices may indeed reduce pain through a unique neural mechanism, one corresponding to increased attention and reduced evaluative/emotional responses.

Thursday, September 15, 2011

Why laughing feels so good...

Robin Dunbar, the evolutionary psychologist at Oxford who has correlated social group size with brain size in evolution, and also argued for the importance of grooming as a group bonding mechanism, has come up with a simple and fascinating observation: social laughter increases pain resistance, suggesting that moving the muscles that are involved in a laugh causes the release of endorphins (Pain thresholds are taken to be a proxy for endorphin release). Here is the abstract from Dunbar et al.:

Although laughter forms an important part of human non-verbal communication, it has received rather less attention than it deserves in both the experimental and the observational literatures. Relaxed social (Duchenne) laughter is associated with feelings of wellbeing and heightened affect, a proximate explanation for which might be the release of endorphins. We tested this hypothesis in a series of six experimental studies in both the laboratory (watching videos) and naturalistic contexts (watching stage performances), using change in pain threshold as an assay for endorphin release. The results show that pain thresholds are significantly higher after laughter than in the control condition. This pain-tolerance effect is due to laughter itself and not simply due to a change in positive affect. We suggest that laughter, through an endorphin-mediated opiate effect, may play a crucial role in social bonding.
In a review James Gorman quotes Dunbar:
“Laughter is very weird stuff, actually,” Dr. Dunbar said. “That’s why we got interested in it.” And the findings fit well with a growing sense that laughter contributes to group bonding and may have been important in the evolution of highly social humans....Social laughter, Dr. Dunbar suggests, relaxed and contagious, is “grooming at a distance,” an activity that fosters closeness in a group the way one-on-one grooming, patting and delousing promote and maintain bonds between individual primates of all sorts.

Wednesday, September 14, 2011

Priming for self-esteem improves performance.

Yet another interesting collaboration involving Ray Dolan from the Wellcome Trust Centre for Neuroimaging.

Social cues have subtle effects on a person, often without them being aware. One explanation for this influence involves implicit priming of trait associations. To study this effect, we activated implicit associations in participants of ‘being Clever’ or ‘being Stupid’ that were task relevant, and studied its behavioural impact on an independent cognitive task (the n-back task). Activating a representation of ‘Clever’ caused participants to slow their reaction times after errors on the working memory task, while the reverse pattern was seen for associations to ‘Stupid’. Critically, these behavioural effects were absent in control conditions. Using functional magnetic resonance imaging, we show that the neural basis of this effect involves the anterior paracingulate cortex (area 32) where activity tracked the observed behavioural pattern, increasing its activity during error monitoring in the ‘Clever’ condition and decreasing in the ‘Stupid’ condition. The data provide a quantitative demonstration of how implicit cues, which specifically target a person’s self-concept, influences the way we react to our own behaviour and point to the anterior paracingulate cortex as a critical cortical locus for mediating these self-concept related behavioural regulations.
(The methods section describes how a scrambled sentence task served as the priming task.)

Tuesday, September 13, 2011

Brain changes following cognitive behavioral therapy for psychosis.

I've always been impressed by work of the sort done by Schwartz and others that shows cognitive behavioral therapy (CBT), when effective for obsessive-compulsive disorder, causes changes in brain activity similar to those caused by drugs that also alleviate symptoms. (One example of a CBT trick: instruct the patient, when symptoms appear, to think "That's not me, that's a part of my brain that is not working.") The journal BRAIN offers an open access article by Kumari et al. that makes further correlations of CBT with brain activity. They observe that in schizophrenia patients whose normal therapy is supplemented with cognitive behavior therapy there is decreased activation in several areas in response to fearful and angry expressions.

The cognitive behaviour therapy for psychosis...showed decreased activation of the inferior frontal, insula, thalamus, putamen and occipital areas to fearful and angry expressions at treatment follow-up compared with baseline. Reduction of functional magnetic resonance imaging response during angry expressions correlated directly with symptom improvement. This study provides the first evidence that cognitive behaviour therapy for psychosis attenuates brain responses to threatening stimuli and suggests that cognitive behaviour therapy for psychosis may mediate symptom reduction by promoting processing of threats in a less distressing way.

Monday, September 12, 2011

Talk about a nasty trick..plus, beta males win

Robert Sapolsky, whose work on stress I've talked about in a number of posts, is a polymath who maintains a number of quirky interests, one of which is describing a bizzare trick the protozoan Toxoplasma uses to reproduce itself, by infecting the brain of a mouse and altering its limbic system so that the poor mouse is sexually attracted to, rather than repelled by, the smell of cat urine (the protozoan requires the cat to sexually reproduce). The abstract:

Cat odors induce rapid, innate and stereotyped defensive behaviors in rats at first exposure, a presumed response to the evolutionary pressures of predation. Bizarrely, rats infected with the brain parasite Toxoplasma gondii approach the cat odors they typically avoid. Since the protozoan Toxoplasma requires the cat to sexually reproduce, this change in host behavior is thought to be a remarkable example of a parasite manipulating a mammalian host for its own benefit. Toxoplasma does not influence host response to non-feline predator odor nor does it alter behavior on olfactory, social, fear or anxiety tests, arguing for specific manipulation in the processing of cat odor. We report that Toxoplasma infection alters neural activity in limbic brain areas necessary for innate defensive behavior in response to cat odor. Moreover, Toxoplasma increases activity in nearby limbic regions of sexual attraction when the rat is exposed to cat urine, compelling evidence that Toxoplasma overwhelms the innate fear response by causing, in its stead, a type of sexual attraction to the normally aversive cat odor.
And, since I'm mentioning Sapolsky, and haven't gotten around to passing on another interesting bit from him, here is his commentary on work by Gusquiere et al. showing that the beta male in a baboon troop can end up winning in the end. Here is the NYTimes review of the work.

Friday, September 09, 2011

Civil conflict correlates with climate change.

A sobering analysis from Hsiang et al.:

It has been proposed that changes in global climate have been responsible for episodes of widespread violence and even the collapse of civilizations. Yet previous studies have not shown that violence can be attributed to the global climate, only that random weather events might be correlated with conflict in some cases. Here we directly associate planetary-scale climate changes with global patterns of civil conflict by examining the dominant interannual mode of the modern climate, the El Niño/Southern Oscillation (ENSO). Historians have argued that ENSO may have driven global patterns of civil conflict in the distant past11, a hypothesis that we extend to the modern era and test quantitatively. Using data from 1950 to 2004, we show that the probability of new civil conflicts arising throughout the tropics doubles during El Niño years relative to La Niña years. This result, which indicates that ENSO may have had a role in 21% of all civil conflicts since 1950, is the first demonstration that the stability of modern societies relates strongly to the global climate.

Thursday, September 08, 2011

Free Will: Neuroscience vs. Philosophy

Kerri Smith offers (PDF here) an update on the perennial debate between neuroscientists and philosophers over free will, it covers findings I've mentioned in previous posts...Haynes and coworkers finding that brain activity in motor cortex areas can be observed one to seven seconds before a subject is aware of willing an action to occur, and Fried et al. making even more compelling observations.

Haynes's 2008 study modernized Libet's earlier experiment: where Libet's EEG technique could look at only a limited area of brain activity, Haynes's fMRI set-up could survey the whole brain; and where Libet's participants decided simply on when to move, Haynes's test forced them to decide between two alternatives. But critics still picked holes, pointing out that Haynes and his team could predict a left or right button press with only 60% accuracy at best. Although better than chance, this isn't enough to claim that you can see the brain making its mind up before conscious awareness, argues Adina Roskies, a neuroscientist and philosopher who works on free will at Dartmouth College in Hanover, New Hampshire. Besides, "all it suggests is that there are some physical factors that influence decision-making", which shouldn't be surprising. Philosophers who know about the science, she adds, don't think this sort of study is good evidence for the absence of free will, because the experiments are caricatures of decision-making. Even the seemingly simple decision of whether to have tea or coffee is more complex than deciding whether to push a button with one hand or the other.

Haynes stands by his interpretation, and has replicated and refined his results in two studies. One uses more accurate scanning techniques3 to confirm the roles of the brain regions implicated in his previous work. In the other, which is yet to be published, Haynes and his team asked subjects to add or subtract two numbers from a series being presented on a screen. Deciding whether to add or subtract reflects a more complex intention than that of whether to push a button, and Haynes argues that it is a more realistic model for everyday decisions. Even in this more abstract task, the researchers detected activity up to four seconds before the subjects were conscious of deciding, Haynes says.

Some researchers have literally gone deeper into the brain. One of those is Itzhak Fried, a neuroscientist and surgeon at the University of California, Los Angeles, and the Tel Aviv Medical Center in Israel. He studied individuals with electrodes implanted in their brains as part of a surgical procedure to treat epilepsy4. Recording from single neurons in this way gives scientists a much more precise picture of brain activity than fMRI or EEG. Fried's experiments showed that there was activity in individual neurons of particular brain areas about a second and a half before the subject made a conscious decision to press a button. With about 700 milliseconds to go, the researchers could predict the timing of that decision with more than 80% accuracy. "At some point, things that are predetermined are admitted into consciousness," says Fried. The conscious will might be added on to a decision at a later stage, he suggests.

Wednesday, September 07, 2011

Behavioral and Brain Science Freebies...

Yet another post in which I pass on some of the goodies that are constantly flowing through my literature scans, rather than losing them as my list of potential posts grows and they are buried forever. Behavioral and Brain Sciences has opened free access to its most cited papers in 2010:

Darwin's mistake: Explaining the discontinuity between human and nonhuman minds
Derek C. Penn, Keith J. Holyoak, Daniel J. Povinelli

Language as shaped by the brain
Morten H. Christiansen, Nick Chater

Emotional responses to music: The need to consider underlying mechanisms
Patrik N. Juslin, Daniel Västfjäll

Deficits in cognitive control correlate with depression and rumination.

Joormann et al. make some observations on 'sticky thoughts.' I've edited their abstract a bit:

Cognitive inflexibility may play an important role in rumination, a risk factor for the onset and maintenance of depressive episodes. In the study reported here, we assessed participants’ ability to either reverse or maintain in working memory the order of three emotional (positive or negative) or three neutral words. Differences (or sorting costs) between response latencies in backward trials, on which participants were asked to reverse the order of the words, and forward trials, on which participants were asked to remember the words in the order in which they were presented, were calculated. [A recognition probe was used to index sorting costs (i.e., differences between response latencies on the forward and the backward trials. The probe word consisting of one of the three words was presented until the subject responded. Participants were instructed to press a key (“1,” “2,” or “3”) to indicate as quickly and as accurately as possible whether the probe was the first, second, or third word (counting forward or backward, as appropriate) in the set they had been instructed to remember.] Compared with control participants, depressed participants had higher sorting costs, particularly when presented with negative words. It is important to note that rumination predicted sorting costs for negative words but not for positive or neutral words in the depressed group. These findings indicate that depression and rumination are associated with deficits in cognitive control.

Tuesday, September 06, 2011

Our economic history

I want to point you to this article by Robert Reich in the Sunday New York Times, which is one the best description of our current economic mess that I have seen. Here is just a fragment of a great graphic summary the article provides (click to enlarge):

Neuroeconomics and the current financial crisis.

Cell press does a really remarkable job of assembling and pointing out important article in seminal areas of research.  I'm wanting in this post to point you to their Neuroscience Newsletter (that anyone can subscribe to) whose current issue emphasizes Neuroeconomics,  It has open access links to important articles. 

Our brains beat with the music...

From Nozaradan et al.:

Feeling the beat and meter is fundamental to the experience of music. However, how these periodicities are represented in the brain remains largely unknown. Here, we test whether this function emerges from the entrainment of neurons resonating to the beat and meter. We recorded the electroencephalogram while participants listened to a musical beat and imagined a binary or a ternary meter on this beat (i.e., a march or a waltz). We found that the beat elicits a sustained periodic EEG response tuned to the beat frequency. Most importantly, we found that meter imagery elicits an additional frequency tuned to the corresponding metric interpretation of this beat. These results provide compelling evidence that neural entrainment to beat and meter can be captured directly in the electroencephalogram. More generally, our results suggest that music constitutes a unique context to explore entrainment phenomena in dynamic cognitive processing at the level of neural networks.

Monday, September 05, 2011

The genetics of cognition

Trends in Cognitive Science has published a special issue on the genetics of cognition that is open access through September.

Twin, family and adoption studies have demonstrated that there is a substantial heritable component to all cognitive functions. The articles in this special issue summarize what is currently known about the genetic underpinnings of these functions and their disorders. At the same time, they highlight just how much there is yet to be discovered in this rapidly advancing field.
Robbins and Kousta provide an overview for the issue.
Review topics include:
-Genetics and criminal responsibility
-Genetics of human episodic memory: dealing with complexity
-The genetics of cognitive ability and cognitive ageing in healthy older people
-Dissecting the genetic architecture of human personality
-Genetics of emotion
-Genetics of autism spectrum disorders
-Understanding risk for psychopathology through imaging gene–environment interactions
-The genetics of cognitive impairment in schizophrenia: a phenomic perspective
-The contribution of imaging genetics to the development of predictive markers for  addictions

Women on the make are better at spotting gay men

These observations by Rule et al. sort of make sense, if you're a woman looking for a potential father of your children, you don't want to waste time dating gay men....

People can accurately infer others’ traits and group memberships across several domains. We examined heterosexual women’s accuracy in judging male sexual orientation across the fertility cycle (Study 1) and found that women’s accuracy was significantly greater the nearer they were to peak ovulation. In contrast, women’s accuracy was not related to their fertility when they judged the sexual orientations of other women (Study 2). Increased sexual interest brought about by the increased likelihood of conception near ovulation may therefore influence women’s sensitivity to male sexual orientation. To test this hypothesis, we manipulated women’s interest in mating using an unobtrusive priming task (Study 3). Women primed with romantic thoughts showed significantly greater accuracy in their categorizations of male sexual orientation (but not female sexual orientation) compared with women who were not primed. The accuracy of judgments of male sexual orientation therefore appears to be influenced by both natural variations in female perceivers’ fertility and experimentally manipulated cognitive frames.

Friday, September 02, 2011

Ironic effects of dietary supplements

Chiou et al. suggest that illusory invulnerability created by taking dietary supplements licenses health-risk behaviors. Their abstract (slightly edited):

The use of dietary supplements and the health status of individuals have an asymmetrical relationship: The growing market for dietary supplements appears not to be associated with an improvement in public health. Building on the notion of licensing, or the tendency for positive choices to license subsequent self-indulgent choices, we argue that because dietary supplements are perceived as conferring health advantages, use of such supplements may create an illusory sense of invulnerability that disinhibits unhealthy behaviors. In two experiments, participants who took placebo pills that they believed were dietary supplements, compared with participants who were told the pills were a placebo, exhibited the licensing effect across multiple forms of health-related behavior: In a first experiment they expressed less desire to engage in exercise and more desire to engage in hedonic activities, and expressed greater preference for a buffet over an organic meal. In a second experiment they walked less to benefit their health. A mediational analysis indicated that perceived invulnerability was an underlying mechanism for these effects. Thus, a license associated with the use of dietary supplements may operate within cycles of behaviors that alternately protect and endanger health.

Thursday, September 01, 2011

Microbes run the world

In my continuing scan of edge.org's annual question, I come across this essay by Stewart Brand, that continues the thread started last week on on how 'we' (humans) are mostly 'they' (microbes). Some clips:

Microbes make up 80 percent of all biomass, says Carl Woese. In one fifth of a teaspoon of seawater there's a million bacteria (and 10 million viruses), Craig Venter says, adding, "If you don't like bacteria, you're on the wrong planet. This is the planet of the bacteria." That means most of the planet's living metabolism is microbial. When James Lovelock was trying to figure out where the gases come from that make the Earth's atmosphere such an artifact of life (the Gaia Hypothesis), it was microbiologist Lynn Margulis who had the answer for him. Microbes run our atmosphere. They also run much of our body. The human microbiome in our gut, mouth, skin, and elsewhere, harbors 3,000 kinds of bacteria with 3 million distinct genes. (Our own cells struggle by on only 18,000 genes or so.) New research is showing that our microbes-on-board drive our immune systems and important portions of our digestion.

Microbial evolution, which has been going on for over 3.6 billion years, is profoundly different from what we think of as standard Darwinian evolution, where genes have to pass down generations to work slowly through the selection filter. Bacteria swap genes promiscuously within generations. They have three different mechanisms for this "horizontal gene transfer" among wildly different kinds of bacteria, and thus they evolve constantly and rapidly. Since they pass on the opportunistically acquired genes to their offspring, what they do on an hourly basis looks suspiciously Lamarckian — the inheritance of acquired characteristics.

Such routinely transgenic microbes show that there's nothing new, special, or dangerous about engineered GM crops. Field biologists are realizing that the the biosphere is looking like what some are calling a pangenome, an interconnected network of continuously circulated genes that is a superset of all the genes in all the strains of a species that form. Bioengineers in the new field of synthetic biology are working directly with the conveniently fungible genes of microbes.

This biotech century will be microbe enhanced and maybe microbe inspired. "Social Darwinism" turned out to be a bankrupt idea. The term "cultural evolution" never meant much, because the fluidity of memes and influences in society bears no relation to the turgid conservatism of standard Darwinian evolution. But "social microbialism" might mean something as we continue to explore the fluidity of traits and vast ingenuity of mechanisms among microbes — quorum sensing, biofilms, metabolic bucket brigades, "lifestyle genes," and the like.