Monday, March 31, 2014

Mechanism of muscle decay on aging, and its reversal.

Humans in their 70's and 80's experience a loss of skeletal muscle mass and strength (sarcopenia) that correlates with an increase in mortality in older populations. One reason this loss occurs is because the regenerative capacity of muscle stem cells (called satellite cells) declines with age as they switch from a quiescent state (from which they can emerge to generate new muscle progenitor cells) to a senescent-like state, which impairs the regeneration process, including activation, proliferation and self-renewal. Sousa-Victor et al. report, in experiments on aging mice, that this switch is caused by derepression of the gene encoding p16INK4a, a regulator of cellular senescence.  They find that genetically silencing p16INK4a in geriatric satellite cells restores quiescence and muscle regenerative functions, suggesting a possible clinical strategy for rejuvenating satellite cells.  I pass on this graphical summary of their results from the review by Li and Belmonte, followed by the abstract of their article.

a. Satellite cells, a type of muscle stem cell, remain quiescent under normal conditions. After muscle damage, satellite cells become activated and re-enter the cell cycle to produce muscle progenitor cells that regenerate new muscle fibres. They also self-renew to replenish the stem-cell population. b, Sousa-Victor et al.3 report that during ageing, geriatric satellite cells lose their reversible quiescent state owing to derepression of the gene encoding p16INK4a, a regulator of cellular senescence. Instead, they adopt a senescent-like state (becoming pre-senescent cells), which impairs the regeneration process, including activation, proliferation and self-renewal.
Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with ageing. Here we report that geriatric satellite cells are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and that this irreversibly affects their intrinsic regenerative and self-renewal capacities. In geriatric mice, resting satellite cells lose reversible quiescence by switching to an irreversible pre-senescence state, caused by derepression of p16INK4a (also called Cdkn2a). On injury, these cells fail to activate and expand, undergoing accelerated entry into a full senescence state (geroconversion), even in a youthful environment. p16INK4a silencing in geriatric satellite cells restores quiescence and muscle regenerative functions. Our results demonstrate that maintenance of quiescence in adult life depends on the active repression of senescence pathways. As p16INK4a is dysregulated in human geriatric satellite cells, these findings provide the basis for stem-cell rejuvenation in sarcopenic muscles.

Friday, March 28, 2014

Our lives are a concept, not a reality.

It is useful to occasionally be reminded of our essential strangeness, something I attempted in my "I-Illusion" web/lecture some years ago. Associate Scientific American editor Ferris Jabr engages this strangeness in his brief essay "Why nothing is truly alive". He notes the amazing life-like moving sculptures of Dutch artist Theo Jansen (see video), and points out how attempts to define life - as NASA has tried in defining the goal of what a search for extra-terrestrial life would look for - have floundered, the simple point being that while the concept of life sometimes has its pragmatic value for our particular human purposes, it does not reflect the reality of the universe outside the mind. Life is a concept, not a reality.
To better understand this argument, it’s helpful to distinguish between mental models and pure concepts. Sometimes the brain creates a representation of a thing: light bounces off a pine tree and into our eyes; molecules waft from its needles and ping neurons in our nose; the brain instantly weaves together these sensations with our memories to create a mental model of that tree. Other times the brain develops a pure concept based on observations — a useful way of thinking about the world. Our idealized notion of “a tree” is a pure concept. There is no such thing as “a tree” in the world outside the mind...Likewise, “life” is an idea. We find it useful to think of some things as alive and others as inanimate, but this division exists only in our heads.
Recognizing life as a concept is, in many ways, liberating. We do not need to recoil from our impulse to endow Mr. Jansen’s sculptures with “life” because they move on their own. The real reason Strandbeest enchant us is the same reason that any so-called “living thing” fascinates us: not because it is “alive,” but because it is so complex and, in its complexity, beautiful.

Thursday, March 27, 2014

Restoring mitochondrial dysfunction associated with aging.

The aging of our bodies is by definition cellular aging, and it is hard to keep track with all the theories on why cells age. One of the most venerable models is that increasing damage to energy producing mitochondria in cells is a fundamental cause of cell decay and death. Mitochondrial energy production is accompanied by a low level of the aberrant production of reactive oxygen species (ROS) that damage mitochondria DNA and proteins. Another model suggested by Sinclair and colleagues is that alterations in nuclear gene expression due to reduced activity of the deacetylase SIRT1 may be the culprit. (SIRT1 is the enzyme linked to the anti-aging activity of resveratrol). Increasing this activity by increasing NAD+ (the energy coenzyme Nicotine Adenine Dinucleotide) levels can reverse age-dependent mitochondrial dysfunction. Here are highlights and the summary of their article.
-A specific decline in mitochondrially encoded genes occurs during aging in muscle
-Nuclear NAD+ levels regulate mitochondrial homeostasis independently of PGC-1α/β
-Declining NAD+ during aging causes pseudohypoxia, which disrupts OXPHOS function
-Raising nuclear NAD+ in old mice reverses pseudohypoxia and metabolic dysfunction

Ever since eukaryotes subsumed the bacterial ancestor of mitochondria, the nuclear and mitochondrial genomes have had to closely coordinate their activities, as each encode different subunits of the oxidative phosphorylation (OXPHOS) system. Mitochondrial dysfunction is a hallmark of aging, but its causes are debated. We show that, during aging, there is a specific loss of mitochondrial, but not nuclear, encoded OXPHOS subunits. We trace the cause to an alternate PGC-1α/β-independent pathway of nuclear-mitochondrial communication that is induced by a decline in nuclear NAD+ and the accumulation of HIF-1α under normoxic conditions, with parallels to Warburg reprogramming. Deleting SIRT1 accelerates this process, whereas raising NAD+ levels in old mice restores mitochondrial function to that of a young mouse in a SIRT1-dependent manner. Thus, a pseudohypoxic state that disrupts PGC-1α/β-independent nuclear-mitochondrial communication contributes to the decline in mitochondrial function with age, a process that is apparently reversible.

Wednesday, March 26, 2014

Out of Sight, Out of Mind

It has been a common supposition that suppressing conscious recall of unpleasant or traumatic memories doesn't prevent their stealthly emotionally damaging unconscious effects. Assuming this, various talk therapies attempt to elicit recall, "working through", and desensitization to, the trauma. Gagnepain at al. use now provide direct evidence that a frontal, top-down, inhibition suppresses both explicit and implicit visual cortex activities that correlate with the memories. They found that suppressing visual memories made it harder for people to later see the suppressed object compared to other recently seen objects. (Brain activity was recorded using functional magnetic resonance imaging (fMRI) while participants either thought of the object image when given its reminder word, or instead tried to stop the memory of the picture from entering their mind.) Here is their abstract:
Suppressing retrieval of unwanted memories reduces their later conscious recall. It is widely believed, however, that suppressed memories can continue to exert strong unconscious effects that may compromise mental health. Here we show that excluding memories from awareness not only modulates medial temporal lobe regions involved in explicit retention, but also neocortical areas underlying unconscious expressions of memory. Using repetition priming in visual perception as a model task, we found that excluding memories of visual objects from consciousness reduced their later indirect influence on perception, literally making the content of suppressed memories harder for participants to see. Critically, effective connectivity and pattern similarity analysis revealed that suppression mechanisms mediated by the right middle frontal gyrus reduced activity in neocortical areas involved in perceiving objects and targeted the neural populations most activated by reminders. The degree of inhibitory modulation of the visual cortex while people were suppressing visual memories predicted, in a later perception test, the disruption in the neural markers of sensory memory. These findings suggest a neurobiological model of how motivated forgetting affects the unconscious expression of memory that may be generalized to other types of memory content. More generally, they suggest that the century-old assumption that suppression leaves unconscious memories intact should be reconsidered.

Tuesday, March 25, 2014

Clash of 'grand theories' of consciousness??

In what strikes me in the most unlikely venue, The Huffington Post, new age guru (also savvy businessman and marketer) Deepak Chopra offers what seems to an equivalent to the "teach the controversy" arguments of the creationists. The title "'Collision Course' in the Science of Consciousness: Grand Theories to Clash at Tucson Conference" suggests that there are two grand theories when in fact there are not. Massive evidence supports the idea that consciousness is accounted for by complex interactions between nerve cells, and Chopra does a nice summary of two central researchers taking this approach:
Christof Koch now teams with psychiatrist and neuroscientist Giulio Tononi in applying principles of integrated information, computation and complexity to the brain's neuronal and network-level electrochemical activities. In their view, consciousness depends on a system's ability to integrate complex information, to compute particular states from among possible states according to algorithms. Deriving a measure of complex integration from EEG signals termed 'phi', they correlate consciousness with critically complex levels of 'phi'.
Regarding the 'hard problem', Koch, Tononi and their physicist colleague Max Tegmark have embraced a form of panpsychism in which consciousness is a property of matter. Simple particles are conscious in a simple way, whereas such particles, when integrated in complex computation, become fully conscious (the 'combination problem' in panpsychism philosophy). Tegmark has termed conscious matter 'perceptronium', and his alliance with Koch and Tononi is Crick's legacy and a major force in the present-day science of consciousness. Their view of neurons as fundamental units whose complex synaptic interactions account for consciousness, also supports widely-publicized, and well-funded 'connectome' and 'brain mapping' projects hoping to capture brain function in neuronal network architecture.
I can see absolutely nothing but gibberish in the vague array alternatives to this sort of approach mentioned by Chopra, Penrose, Hameroff and others: non-computational, quantum superpositional, connected to spacetime geometry, involving coherent cellular microtubule states. Elegant hand waving perhaps, but where is the model? How is it to be tested?

Monday, March 24, 2014

Shaping memory accuracy by TCDS

Here is yet another example, from Zwissler et al., of how different brain processes, in this case memory, can be tweaked by trans-cranial direct current stimulation (DCTS) - passing very weak currents between electrodes places on our scalps. In most of these reports, there are suggestions of possible future therapeutic applications. The abstract:
Human memory is dynamic and flexible but is also susceptible to distortions arising from adaptive as well as pathological processes. Both accurate and false memory formation require executive control that is critically mediated by the left prefrontal cortex (PFC). Transcranial direct current stimulation (tDCS) enables noninvasive modulation of cortical activity and associated behavior. The present study reports that tDCS applied to the left dorsolateral PFC (dlPFC) shaped accuracy of episodic memory via polaritiy-specific modulation of false recognition. When applied during encoding of pictures, anodal tDCS increased whereas cathodal stimulation reduced the number of false alarms to lure pictures in subsequent recognition memory testing. These data suggest that the enhancement of excitability in the dlPFC by anodal tDCS can be associated with blurred detail memory. In contrast, activity-reducing cathodal tDCS apparently acted as a noise filter inhibiting the development of imprecise memory traces and reducing the false memory rate. Consistently, the largest effect was found in the most active condition (i.e., for stimuli cued to be remembered). This first evidence for a polarity-specific, activity-dependent effect of tDCS on false memory opens new vistas for the understanding and potential treatment of disturbed memory control.

Friday, March 21, 2014

Do brain workouts work?

I've done numerous posts on brain training websites, and have ended up enjoying returning to the one started up by Michael Merzenich, Posit Science. I want to pass on this link to the latest article I've seen discussing the usefulness of brain training regimes. The article points out that the science has not kept up with the hype. But, one study has suggested that games engaging attention, speed of processing, and short term memory improve general cognitive skills for as long as 5-10 years. Here is a clip:
In January, the largest randomized controlled trial of cognitive training in healthy older adults found that gains in reasoning and speed through brain training lasted as long as 10 years. Financed by the National Institutes of Health, the Active study (Advanced Cognitive Training for Independent and Vital Elderly) recruited 2,832 volunteers with an average age of 74.
The participants were divided into three training groups for memory, reasoning and speed of processing, as well as one control group. The groups took part in 10 sessions of 60 to 75 minutes over five to six weeks, and researchers measured the effect of training five times over the next 10 years. Five years after training, all three groups still demonstrated improvements in the skills in which they had trained. Notably, the gains did not carry over into other areas. After 10 years, only the reasoning and speed-of-processing groups continued to show improvement...The researchers also found that people in the reasoning and speed-of-mental-processing groups had 50 percent fewer car accidents than those in the control group.

Thursday, March 20, 2014

A debate on what faces can tell us.

Security agencies are developing facial emotion profiling software for use at checkpoints, while Apple and Google are working on using your laptop camera to tell them what kind of mood you are in while shopping online. Such approaches are based on the assumption that a basic set of facial emotions are invariant across cultures and universally understood. A large body of work, starting with Charles Darwin and especially since the 1960's done by Paul Ekman and others has substantiated this idea.

In yet another New York Times Op-Ed advertisement wanting to raise the visibility of some basic research, Barrett and collaborators make the heretical claim that this assumption is wrong and point to their articles questioning Ekman's original research protocol of asking individuals in cultures isolated from outside contact for many centuries to match photographs of faces with a preselected set of emotion words. They suspected that providing subjects with a preselected set of emotion words might inadvertently prime the subjects, in effect hinting at the answer, and thus skew the results. In one set of experiments subjects not given any clues and asked to freely describe the emotion on a face or state whether emotions of two faces were the same or different performed less well. When further steps were taken to prevent priming, performance fell further.

A rejoinder from Paul Ekman and Dacher Keltner points out that a number of studies supporting Charles Darwin's original observations suggesting that facial movements are evolved behaviors have avoided the issues raised by Barrett et al. by simply measuring spontaneous facial expressions in different cultures, along with the physiological activity that differed when various universal facial expressions occurred.  It seems reasonable that a universal facial emotional repertoire might in practice be skewed by culturally relative linguistic conventions,  thus helping to explain Barrett et al's observations.

Wednesday, March 19, 2014

Magical thinking in auction biding.

Newman and Bloom do another demonstration of how common magical thinking is in our society by analyzing the influence of physical contact on how much people pay at celebrity auctions:
Contagion is a form of magical thinking in which people believe that a person’s immaterial qualities or essence can be transferred to an object through physical contact. Here we investigate how a belief in contagion influences the sale of celebrity memorabilia. Using data from three high-profile estate auctions, we find that people’s expectations about the amount of physical contact between the object and the celebrity positively predicts the final bids for items that belonged to well-liked individuals (e.g., John F. Kennedy) and negatively predicts final bids for items that belonged to disliked individuals (e.g., Bernard Madoff). A follow-up experiment further suggests that these effects are driven by contagion beliefs: when asked to bid on a sweater owned by a well-liked celebrity, participants report that they would pay substantially less if it was sterilized before they received it. However, sterilization increases the amount they would pay for a sweater owned by a disliked celebrity. These studies suggest that magical thinking may still have effects in contemporary Western societies and they provide some unique demonstrations of contagion effects on real-world purchase decisions.

Tuesday, March 18, 2014

Control over memory retrieval is predicted by heart rate variability.

Here is a fascinating observation from Gillie et al., who find that a physiological marker, heart rate variability, correlates with a person's ability to control unwanted memories. They use a think/no-think (TNT) task to demonstrate this:
In the TNT paradigm, participants learn a list of cue-response word pairs (e.g., “Tape-Radio”). They are then repeatedly presented with the cues studied earlier (e.g., “Tape”). In the think trials, they are asked to think of the response word (e.g., “Radio”). In the no-think trials, they are asked to prevent recall of the response word. Thus, in the latter case, participants attempt to intentionally stop the retrieval of a memory when presented with a cue. Successful suppression of a target memory should reduce its accessibility at a later point; therefore, recall for the response words is assessed at the end of the experiment. A recent meta-analysis of studies in which this paradigm has been used showed that, on average, people tend to have significantly lower recall of no-think items than of baseline items (word pairs that were studied in the initial phase but not presented in the experimental phase; Levy & Anderson, 2008). This finding, known as the negative-control effect, is taken to be evidence that people can successfully inhibit retrieval of an unwanted memory and that doing so impairs recall for that particular memory.
Here is their abstract:
Stopping retrieval of unwanted memories has been characterized as a process that requires inhibition. However, little research has examined the relationship between control over memory retrieval and individual differences in inhibitory control. Higher levels of resting heart rate variability (HRV) are associated with greater inhibitory control, as indicated by better performance on a number of cognitive, affective, and motor tasks. Therefore, we tested the hypothesis that higher levels of resting HRV predict enhanced memory inhibition as indexed by performance on the think/no-think task. Efforts to suppress no-think word pairs resulted in impaired recall for those items, as in past studies. Moreover, higher levels of resting HRV were associated with more successful suppression, as indicated by lower recall of the to-be-avoided stimuli relative to baseline stimuli. These findings are among the first to suggest that physiological markers of inhibitory control can be used to index a person’s capacity to control unwanted memories.

Monday, March 17, 2014

Some homilies on wisdom - older and wiser.

Because at ~72 years of age I am becoming more aware of how much time I have left rather than how long I have lived, I enjoyed a recent article by Phyllis Korkki. Here are some clips, edits, and paraphrases from the article:

Wisdom defined as maintaining positive well-being and kindness in the face of challenges is one of the most important qualities one can possess to age successfully.

In a 1970’s study by Vivian Clayton, decision makers asked to characterize a wise person stressed three key components: cognition, reflection and compassion.

Elkhonon Goldberg, a neuroscientist in New York and author of “The Wisdom Paradox,” says that “cognitive templates” develop in the older brain based on pattern recognition, and that these can form the basis for wise behavior and decisions.

…acceptance of aging is necessary for growth, but it’s not a resigned acceptance; it’s an embracing acceptance.

From Ursula Staudinger, a life span psychologist and professor at Columbia University: True personal wisdom involves five elements. They are self-insight; the ability to demonstrate personal growth; self-awareness in terms of your historical era and your family history; understanding that priorities and values, including your own, are not absolute; and an awareness of life’s ambiguities.

Modern definitions of wisdom tend to stress kindness, a reduction in self-centeredness, understanding situations from multiple perspectives, showing tolerance as a result

There’s evidence that people who rank high in neuroticism (tendency to be in a negative state for long periods of time) are unlikely to be wise…They see things in a self-centered and negative way and so they fail to benefit emotionally from experience, even though they may be very intelligent.

Daniel Goleman (author of “Emotional Intelligence”: One aspect of wisdom is having a very wide horizon which doesn’t center on ourselves, or even on our group or organization…an important sign of wisdom is “generativity,” a term used by the psychologist Erik Erikson… Generativity means giving back without needing anything in return…The form of giving back could be creative, social, personal or financial.

,,,there’s a point in life when a fundamental shift occurs, and people start thinking about how much time they have left rather than how long they have lived. Reflecting on the meaning and structure of their lives can help people thrive after the balance shifts and there is much less time left than has gone before.

Friday, March 14, 2014

Fat hurts, and exercise helps, the brain.

Gretchen Reynolds points to work by Erion et al.. showing that in obese mice inflammatory cytokines released by fat tissue enter the brain and cause nerve inflammation in the hippocampus, leading to poor learning and memory skills. Apparently obesity weakens the blood-brain barrier that normally would prevent entry of the inflammatory cytokines. (Adipose tissue in obese humans also is a source of proinflammatory cytokines). The authors found that treadmill training could restore the cognitive deficits and normalize hippocampal synaptic function. The same result could be obtained by simply removing fat tissue through lipectomy. Introduction of excess fat tissue into normal animals caused central inflammation and decay in cognitive and synaptic function. Finally they found that a blocker of the interleukin-1 receptors in the hippocampus protected the hippocampus from inflammation. This work "supports a central role for IL1-mediated neuroinflammation as a mechanism for cognitive deficits in obesity and diabetes." Here is their technical abstract:
Adipose tissue is a known source of proinflammatory cytokines in obese humans and animal models, including the db/db mouse, in which obesity arises as a result of leptin receptor insensitivity. Inflammatory cytokines induce cognitive deficits across numerous conditions, but no studies have determined whether obesity-induced inflammation mediates synaptic dysfunction. To address this question, we used a treadmill training paradigm in which mice were exposed to daily training sessions or an immobile belt, with motivation achieved by delivery of compressed air on noncompliance. Treadmill training prevented hippocampal microgliosis, abolished expression of microglial activation markers, and also blocked the functional sensitization observed in isolated cells after ex vivo exposure to lipopolysaccharide. Reduced microglial reactivity with exercise was associated with reinstatement of hippocampus-dependent memory, reversal of deficits in long-term potentiation, and normalization of hippocampal dendritic spine density. Because treadmill training evokes broad responses not limited to the immune system, we next assessed whether directly manipulating adiposity through lipectomy and fat transplantation influences inflammation, cognition, and synaptic plasticity. Lipectomy prevents and fat transplantation promotes systemic and central inflammation, with associated alterations in cognitive and synaptic function. Levels of interleukin 1β (IL1β) emerged as a correlate of adiposity and cognitive impairment across both the treadmill and lipectomy studies, so we manipulated hippocampal IL1 signaling using intrahippocampal delivery of IL1 receptor antagonist (IL1ra). Intrahippocampal IL1ra prevented synaptic dysfunction, proinflammatory priming, and cognitive impairment. This pattern supports a central role for IL1-mediated neuroinflammation as a mechanism for cognitive deficits in obesity and diabetes.

Thursday, March 13, 2014

Several perspectives on rich versus poor.

The latest issue of Psychological Science has several articles reflecting different perspectives on rich and poor people:

An analysis noting that residents of poor nations have a greater sense of meaning in life than residents of wealthy nations:
Using Gallup World Poll data, we examined the role of societal wealth for meaning in life across 132 nations. Although life satisfaction was substantially higher in wealthy nations than in poor nations, meaning in life was higher in poor nations than in wealthy nations. In part, meaning in life was higher in poor nations because people in those nations were more religious. The mediating role of religiosity remained significant after we controlled for potential third variables, such as education, fertility rate, and individualism. As Frankl (1963) stated in Man’s Search for Meaning, it appears that meaning can be attained even under objectively dire living conditions, and religiosity plays an important role in this search.
Observations on distorted perceptions of incomes and income inequality in America:
Three studies examined Americans’ perceptions of incomes and income inequality using a variety of criterion measures. Contrary to recent findings indicating that Americans underestimate wealth inequality, we found that Americans not only overestimated the rise of income inequality over time, but also underestimated average incomes. Thus, economic conditions in America are more favorable than people seem to realize. Furthermore, ideological differences emerged in two of these studies, such that political liberals overestimated the rise of inequality more than political conservatives. Implications of these findings for public policy debates and ideological disagreements are discussed.
And, an examination of cognitive and behavioral implication of self-affirmation among the poor:
The poor are universally stigmatized. The stigma of poverty includes being perceived as incompetent and feeling shunned and disrespected. It can lead to cognitive distancing, diminish cognitive performance, and cause the poor to forego beneficial programs. In the present research, we examined how self-affirmation can mitigate the stigma of poverty through randomized field experiments involving low-income individuals at an inner-city soup kitchen. Because of low literacy levels, we used an oral rather than written affirmation procedure, in which participants verbally described a personal experience that made them feel successful or proud. Compared with nonaffirmed participants, affirmed individuals exhibited better executive control, higher fluid intelligence, and a greater willingness to avail themselves of benefits programs. The effects were not driven by elevated positive mood, and the same intervention did not affect the performance of wealthy participants. The findings suggest that self-affirmation can improve the cognitive performance and decisions of the poor, and it may have important policy implications.

Wednesday, March 12, 2014

A technique for enhancing error awareness in older age.

Harty et al. note yet another salutary effect of transcranial direct current stimulation. A small voltage applied across the right dorsolateral prefrontal cortex enhances error awareness (by 10-12%) in older people. Their studies were done on 106 healthy oder adults 65-86 years of were recruited for four separate experiments. They used.
...a Go/No-go response inhibition task in which subjects are presented with a serial stream of single-color words, with congruency between the semantic meaning of the word and its font color manipulated across trials. Subjects were trained to respond with a single-speeded left mouse button press in situations where the meaning of the word and the font color in which it was presented were congruent (Go trial) and to withhold this response when either of two different scenarios arose: (1) when the word presented on the current trial was the same as that presented on the preceding trial (Repeat No-go trial), and (2) when the meaning of the word and its font color did not match (Stroop No-go trial). In the event of a commission error (failure to withhold to either of these No-go trials), subjects were trained to signal their “awareness” by making a speeded right mouse button press... Stimulation was delivered by a battery-driven DC Brain Stimulator Plus (NeuroConn), through a pair of 35 cm2 saline-soaked sponge electrodes. Current strength was 1 mA in all experiments. This produced current densities of 0.028 mA/cm2 at the skin surface of the scalp...In all four experiments, subjects underwent both Real and Sham tDCS in a single-blind, crossover manner.
Their abstract:
The ability to detect errors during cognitive performance is compromised in older age and in a range of clinical populations. This study was designed to assess the effects of transcranial direct current stimulation (tDCS) on error awareness in healthy older human adults. tDCS was applied over DLPFC while subjects performed a computerized test of error awareness. The influence of current polarity (anodal vs cathodal) and electrode location (left vs right hemisphere) was tested in a series of separate single-blind, Sham-controlled crossover trials, each including 24 healthy older adults (age 65–86 years). Anodal tDCS over right DLPFC was associated with a significant increase in the proportion of performance errors that were consciously detected, and this result was recapitulated in a separate replication experiment. No such improvements were observed when the homologous contralateral area was stimulated. The present study provides novel evidence for a causal role of right DLPFC regions in subserving error awareness and marks an important step toward developing tDCS as a tool for remediating the performance-monitoring deficits that afflict a broad range of populations.

Tuesday, March 11, 2014

Time, Money, and Morality

Gino and Mogilner note "It seems that a day does not go by without some unethical behavior by a politician, movie star, professional athlete, or high-ranking executive making the headlines. Although less sensational, revelations of cheating have also crept into the sciences, and continue to show up in classrooms, businesses, and marriages."

They proceed to reflect on unethical behavior in people who also strive to maintain a positive self-concept, with morality being central to peoples' self-image. They:
...focus on two triggers that may influence self-reflection and are ubiquitous enough in the environment to have a chance at instigating a widespread effect on unethical behavior: money and time...We specifically predicted that priming people to think about time, rather than money, would lead them to behave more ethically by encouraging them to reflect on who they are and making them more conscious of how they conduct themselves so as to maintain a positive self-image. We tested this hypothesis across four experiments in which we primed participants to think about time or money and observed their tendencies to cheat for monetary or personal gain.
In a first experiment they primed participants with money, time, or neither and then completed a numbers game in which they had the opportunity to cheat by overstating their performance, thereby taking unearned money. Participants primed in the money condition were more likely to cheat.

The second experiment used the numbers game with time or money primes but half the participants were told “This game is an intelligence test that is designed to assess your likelihood to be successful in the future.” and the other half told “This game is a personality test that is designed to assess what type of person you are.” As in the first experiment, participants threw their actual matrix work sheets into a recycle bin, so that they believed they could overreport their performance (i.e., cheat) without getting caught. "In actuality, as in Experiment 1, we were able to match participants’ work sheets with the collection slips on which they reported their performance." The result: "when the game was framed as an intelligence test did thinking about money lead to greater cheating than thinking about time. When the game was framed as a personality test, there was no difference in cheating between the money and time conditions.

A third experiment manipulated self-reflection with a mirror to find that when self-reflection was triggered through the use of a mirror, participants primed with money behaved the same way as those primed with time.

The fourth experiment suggested that "priming time reduces cheating by increasing self-reflection, and priming money increases cheating by lowering self-reflection. By measuring self-reflection directly through self-reports, this experiment provided further evidence for the hypothesized role of self-reflection as the psychological mechanism linking time, money, and morality."

Here is the abstract of the article:
Money, a resource that absorbs much daily attention, seems to be involved in much unethical behavior, which suggests that money itself may corrupt. This research examined a way to offset such potentially deleterious effects—by focusing on time, a resource that tends to receive less attention than money but is equally ubiquitous in daily life. Across four experiments, we examined whether shifting focus onto time can salvage individuals’ ethicality. We found that implicitly activating the construct of time, rather than money, leads individuals to behave more ethically by cheating less. We further found that priming time reduces cheating by making people reflect on who they are. Implications for the use of time primes in discouraging dishonesty are discussed.

Monday, March 10, 2014

Default mode network: the seat of literary creativity?

Wise et al. offer an article with the title of this post in Trends in Cognitive Sciences that comments on the brain areas that consistently become active in different subjects when spoken and written versions of a narrative are presented. They found
...a distribution of correlated activity in the midline posterior cortex and bilateral posterior inferior parietal cortex. This forms the posterior part of the so-called default mode network (DMN; Figure 1), a system classically associated with the introspective mind. It has been observed before, in another meta-analysis of language studies, one that set out to reveal the semantic system [ref]. The authors of that review, and others since (ref), have discussed how memories, semantic and personal, emotions, theory of mind, and no doubt many other mental functions are linked through the DMN. This would suggest that overlapping components of the DMN are functionally interconnected with many separate brain systems, including those for language and semantics, and indeed this is turning out to be the case (refs).

Spot the literary network: the default mode network (DMN) viewed from different angles (colors are intended for illustrative purposes only; data from [ref]). The medial posterior cingulate (PCC) and inferior posterior parietal components (IPP) were implicated in linguistic processing by Regev et al. [ref], but we suggest that due to the widespread connectivity of the DMN, these regions are related to higher order ‘literary’ processing.

Friday, March 07, 2014

Optimism correlates with poor results

Richtel points to work by Sevincer et al. that makes the counter-intuitive observation that optimistic language in newspaper articles and presidential addresses is a predictor of poor economic performance. This actually is consonant with research that has shown that fantasies not tempered by realistic assessment of challenges are less likely to yield results. (People who fantasize about the success of their with control program are less likely to loose pounds). Perhaps people who fantasize an imaged outcome imagine that obtaining it will be easy, and thus work less hard. More sober assessment yields better results.
Previous research has shown that positive thinking, in the form of fantasies about an idealized future, predicts low effort and poor performance. In the studies reported here, we used computerized content analysis of historical documents to investigate the relation between positive thinking about the future and economic development. During the financial crisis from 2007 to 2009, the more weekly newspaper articles in the economy page of USA Today contained positive thinking about the future, the more the Dow Jones Industrial Average declined in the subsequent week and 1 month later. In addition, between the New Deal era and the present time, the more presidential inaugural addresses contained positive thinking about the future, the more the gross domestic product and the employment rate declined in the presidents’ subsequent tenures. These counterintuitive findings may help reveal the psychological processes that contribute to an economic crisis.

Thursday, March 06, 2014

Dangerous behaviors and the corporate consumption complex.

Mark Bittman points to Nicholas Freudenberg's new book,  a right-on exposition and summary of
...“the corporate consumption complex,” an alliance of corporations, banks, marketers and others that essentially promote and benefit from unhealthy lifestyles... it’s unlikely there’s a cabal that sits down and asks, “How can we kill more kids tomorrow?” But Freudenberg details how six industries — food and beverage, tobacco, alcohol, firearms, pharmaceutical and automotive — use pretty much the same playbook to defend the sales of health-threatening products. This playbook, largely developed by the tobacco industry, disregards human health and poses greater threats to our existence than any communicable disease you can name...All of these industries work hard to defend our “right” — to smoke, feed our children junk, carry handguns and so on — as matters of choice, freedom and responsibility. Their unified line is that anything that restricts those “rights” is un-American...Yet each industry, as it (mostly) legally can, designs products that are difficult to resist and sometimes addictive... The food industry has created combinations that most appeal to our brains’ instinctual and learned responses.
...we need to be asking not “Do junk food companies have the right to market to children?” but “Do children have the right to a healthy diet?” (In Mexico, the second question has been answered positively. Shamefully, we have yet to take that step.) The question is not only, “Do we have a right to bear arms?” but also “Do we have the right to be safe in our streets and schools?” In short, says Freudenberg: “The right to be healthy trumps the right of corporations to promote choices that lead to premature death and preventable illnesses. Protecting public health is a fundamental government responsibility; a decent society should not allow food companies to convince children to buy food that’s bad for them or to encourage a lifetime of unhealthy eating.”

Wednesday, March 05, 2014

More on building brains with video games

Nick Bilton does a brief piece on how trying to win various kinds of video games enhances subsequent performance on real world attention and memory tests.
Daphné Bavelier, a neuroscientist with the University of Rochester, found that people who play first-person shooter video games for two weeks can improve visual attention, mental reasoning and decision-making skills. A 2007 study by Iowa State University psychologists compared surgeons who played video games to those who didn’t and found that, during laparoscopic surgeries, the gamers were 27 percent faster and made 37 percent fewer mistakes than nongamers. And decades of research around Tetris has shown that playing it for extended periods may increase memory and cognitive skills.
....the goal is to figure out what makes a game addictive on a neurological level, then to couple this with brain research showing how play can improve the mind...imagine five years from now that you go to the doctor with a problem and he prescribes an F.D.A.-approved video game for you to download and play for two weeks.

Tuesday, March 04, 2014

Want to remember something? Have some coffee!

Here is the brief abstract from Borota et al., followed by a graphic summary of the results offered by Favila and Kuhl:
It is currently not known whether caffeine has an enhancing effect on long-term memory in humans. We used post-study caffeine administration to test its effect on memory consolidation using a behavioral discrimination task. Caffeine enhanced performance 24 h after administration according to an inverted U-shaped dose-response curve; this effect was specific to consolidation and not retrieval. We conclude that caffeine enhanced consolidation of long-term memories in humans.

Figure: Effect of post-encoding caffeine on memory. On day 1, subjects viewed a series of images of everyday objects and made a judgment about whether each image was likely to be found indoors or outdoors. Immediately after completing this task, they took either caffeine or placebo. Measured caffeine levels fully returned to baseline by the next day. On day 2, subjects were given a surprise memory test. Subjects viewed a series of images and decided whether each image was new (not seen on day 1), old (identical to one of the images from day 1) or similar (a different exemplar of one of the images seen on day 1). The probability of correctly labeling similar images as similar (instead of old) was reflected by a lure discrimination index that corrected for potential response bias. Subjects who received 200 or 300 mg of caffeine after the study period on day 1 showed enhanced lure discrimination on day 2 compared with subjects who received placebo. At 100 mg, caffeine did not enhance test performance, nor did caffeine administered just before the memory test (not shown).

Monday, March 03, 2014

Cognitive aging - a dark side to environmental support?

Lindenberger and Mayr make some very interesting points on the consequences of shifting during aging from self initiation to environmental support in performing tasks. This hits me right between the eyes, as I have been noticing lately how much more likely I am to be working on tasks that are generated by, or reactive to, to my immediate physical, social, financial environment than on projects (like generating music and writing) that I initiate and stay focused on. The Lindenberger and Mayr paper (available to motivated readers who email me) reviews a number of studies beyond the original work on memory by Craik, studies that generalize the effects of self initiated versus environmental support to other cognitive areas such as visual and auditory control. Across processing stages and modalities, older adults are more likely to be guided by external cues than younger adults are. Here I pass on summary points, abstract, and a clip from the discussion.
• Perceptual salience rather than attentional focus governs stimulus processing in old age.
• Older adults rely more on environmental prompts for action than younger adults do.
• Environmental support helps older adults to perform but results in loss of internal control.
• The structure of the environment matters, especially for older adults.
It has been known for some time that memory deficits among older adults increase when self-initiated processing is required and decrease when the environment provides task-appropriate cues. We propose that this observation is not confined to memory but can be subsumed under a more general developmental trend. In perception, learning or memory, and action management, older adults often rely more on external information than younger adults do, probably both as a direct reflection and indirect adaptation to difficulties in internally triggering and maintaining cognitive representations. This age-graded shift from internal towards environmental control is often associated with compromised performance. Cognitive aging research and the design of aging-friendly environments can benefit from paying closer attention to the developmental dynamics and implications of this shift.
Environmental support has a bright and a dark side: it helps aging individuals to perform but comes with a loss in internal control. It follows that the environment matters, especially in old age. The initiation and maintenance of internal control are costly, both cognitively and metabolically and these costs appear to increase from early to late adulthood. By the time they have reached old age, individuals have acquired a behavioral repertoire that is likely to match the regularities and affordances of the environments they live in. The tendency of older adults, both automatic and deliberate, to outsource control to the environment may be inefficient at times, but cost-effective in the long run if the cuing structure of the environment corresponds to their goals and needs. Engineers, psychologists, and aging individuals themselves need to keep this in mind as they design and use adaptive technology in the pursuit of successful aging.