Saturday, October 03, 2015

Watching sleep deprivation cause a decline in prefrontal control of emotion.

From Simon et al.:
Sleep deprivation has been shown recently to alter emotional processing possibly associated with reduced frontal regulation. Such impairments can ultimately fail adaptive attempts to regulate emotional processing (also known as cognitive control of emotion), although this hypothesis has not been examined directly. Therefore, we explored the influence of sleep deprivation on the human brain using two different cognitive–emotional tasks, recorded using fMRI and EEG. Both tasks involved irrelevant emotional and neutral distractors presented during a competing cognitive challenge, thus creating a continuous demand for regulating emotional processing. Results reveal that, although participants showed enhanced limbic and electrophysiological reactions to emotional distractors regardless of their sleep state, they were specifically unable to ignore neutral distracting information after sleep deprivation. As a consequence, sleep deprivation resulted in similar processing of neutral and negative distractors, thus disabling accurate emotional discrimination. As expected, these findings were further associated with a decrease in prefrontal connectivity patterns in both EEG and fMRI signals, reflecting a profound decline in cognitive control of emotion. Notably, such a decline was associated with lower REM sleep amounts, supporting a role for REM sleep in overnight emotional processing. Altogether, our findings suggest that losing sleep alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality.

Friday, October 02, 2015

Ig Nobel Prizes for 2015

This year’s Ig Nobel Prizes, awarded in an annual ceremony in Harvard University’s Sanders Theater:
Chemistry prize - for inventing a chemical recipe to partially un-boil an egg.
Physics prize - for testing the biological principle that nearly all mammals empty their bladders in about 21 seconds (bigger bladders gush faster on emptying).
Literature prize - for discovering that the word "huh?" (or its equivalent) seems to exist in every human language — and for not being quite sure why.
Economics prize - to the Bangkok, Thailand, Metropolitan Police, for offering to pay policemen extra cash if the policemen refuse to take bribes.
Medicine prize - for experiments to study the biomedical benefits or biomedical consequences of intense kissing (and other intimate, interpersonal activities).
Mathematics prize - for trying to use mathematical techniques to determine whether and how Moulay Ismael the Bloodthirsty, the Sharifian Emperor of Morocco, managed, during the years from 1697 through 1727, to father 888 children.
Biology prize - for observing that when you attach a weighted stick to the rear end of a chicken, the chicken then walks in a manner similar to that in which dinosaurs are thought to have walked.
Diagnostic Medicine prize - for determining that acute appendicitis can be accurately diagnosed by the amount of pain evident when the patient is driven over speed bumps.
Physiology and Entomology prize - Awarded jointly to two individuals: Justin Schmidt [USA, CANADA], for painstakingly creating the Schmidt Sting Pain Index, which rates the relative pain people feel when stung by various insects; and to Michael L. Smith [USA, UK, THE NETHERLANDS], for carefully arranging for honey bees to sting him repeatedly on 25 different locations on his body, to learn which locations are the least painful (the skull, middle toe tip, and upper arm). and which are the most painful (the nostril, upper lip, and penis shaft).
For a full description of recipients and journal references, see this link.

Thursday, October 01, 2015

Brain system for mental orientation in space, time, and person.

Peer and collaborators show that mental orientation in space, time, and person produces a sequential posterior–anterior pattern of activity in each participant’s brain.
Processing of spatial, temporal, and social relations relies on mental cognitive maps, on which the behaving self is oriented relative to different places, events, and people. Using high-resolution functional MRI scanning in individual subjects, we show that mental orientation in space, time, and person produces a sequential posterior–anterior pattern of activity in each participant’s brain. These activations are adjacent and partially overlapping, highlighting the relation between mental orientation in these domains. Furthermore, the activity is highly overlapping with the brain’s default-mode network, a system involved in self-referential processing. These findings may shed new light on fundamental cognitive processing of space, time, and person and alter our understanding of disorientation phenomena in neuropsychiatric disorders such as Alzheimer’s disease.

Midsagittal cortical activity during orientation in space, time, and person. (A) Domain-specific activity in a representative subject, identified by contrasting activity between each orientation domain and the other two domains. The precuneus region is active in all three orientation domains, and the medial prefrontal cortex only in person and time orientation. Dashed black lines represent the limit of the scanned region in this subject. (B) Precuneus activity in four subjects, demonstrating a highly consistent posterior–anterior organization (white dashed line); all other subjects showed the same activity pattern (Fig. S1). (C) Group average (n = 16) of event-related activity in independent experimental runs demonstrates the specificity of each cluster to one orientation domain. Lines represent activity in response to space (blue), time (green), and person (red) conditions. Error bars represent SEM between subjects. (D) Group average of beta plots from volume-of-interest GLM analysis, showing highly significant domain-specific activity. Error bars represent SEM between subjects. P, person; S, space; T, time.

Wednesday, September 30, 2015

Does exercise change your brain?

After yesterday's post suggesting no effects of common dietary supplements on cognitive changes with aging, I thought I would note work regarding exercise and brain health. mentioned by Reynolds, in particular a study by Burzynska et al. that monitored the daily activities of non-athletes:
...the most physically active elderly volunteers, according to their activity tracker data, had better oxygenation and healthier patterns of brain activity than the more sedentary volunteers — especially in parts of the brain, including the hippocampus, that are known to be involved in improved memory and cognition, and in connecting different brain areas to one another. Earlier brain scan experiments by Dr. Burzynska and her colleagues had established that similar brain activity in elderly people is associated with higher scores on cognitive tests.
Again, there is the caveat that a correlation does not prove a cause.

Tuesday, September 29, 2015

Can dietary supplements fight cognitive decline?

Maybe not...It is known that people who eat diets rich in fish and antioxidants have better brain health, but this association does not prove cause and effect. Rabin points to a recent massive NIH study of ~3,500 subjects that finds no cognitive effects of dietary supplementation wtih long-chain polyunsaturated fatty acids (LCPUFAs) (1 g) and/or lutein (10 mg)/zeaxanthin (2 mg) (tested vs placebo in a factorial design). All participants were also given varying combinations of vitamins C, E, beta carotene, and zinc. Participants,recruited by retinal specialists in 82 US academic and community medical centers as being at risk for developing late age-related macular degeneration, underwent cognitive tests every two years during the 5-year study. The bottom line: "A total of 89% (3741/4203) of the Age-Related Eye Disease Study 2 participants consented to the ancillary cognitive function study and 93.6% (3501/3741) underwent cognitive function testing. The mean (SD) age of the participants was 72.7 (7.7) years and 57.5% were women. There were no statistically significant differences in change of scores for participants randomized to receive supplements vs those who were not."

Monday, September 28, 2015

Humanity as a Competitive Advantage

Some clips from a review by Tony Schwartz, of Geoff Colvin's new book “Humans Are Underrated: What High Achievers Know That Brilliant Machines Never Will.”
…computers are rapidly getting better – often far better — than humans are in dozens of areas…analyzing legal cases, providing financial advice, diagnosing illnesses, driving cars and even fighting wars, with battlefield robots and drones. “Affective” computing makes it possible for these machines to understand human emotions and measure levels of stress, often better than we can ourselves.
From Oxford Economics, a research firm: skills employers said they would need more of in the next five to 10 years were not so much analytic and technical ones as they were “relationship building, teaming, co-creativity, brainstorming, cultural sensitivity and ability to manage diverse employees – the skills… of “social interaction.”…organizations will build competitive advantage through qualities such as empathy, care, attunement, self-awareness and even generosity….The more valued, appreciated, cared for and taken care of we feel, the more secure and trusting we become, the less preoccupied by fear, and the more likely we are to generate our highest value.
…leaders in the workplace must become not just chief executive officers, but also chief energy officers, because their energy – and emotions – are so contagious, for better or for worse.

Friday, September 25, 2015

Is "gaydar" a myth?

Cox et al. contest work by Rule et al. that I mentioned in a previous post and suggest that the idea of "gaydar" is a myth. (Use gaydar as a search term in the search box in the left column for other posts on this topic.)
In the present work, we investigate the pop cultural idea that people have a sixth sense, called “gaydar,” to detect who is gay. We propose that “gaydar” is an alternate label for using stereotypes to infer orientation (e.g., inferring that fashionable men are gay). Another account, however, argues that people possess a facial perception process that enables them to identify sexual orientation from facial structure (Rule et al., 2008). We report five experiments testing these accounts. Participants made gay-or-straight judgments about fictional targets that were constructed using experimentally-manipulated stereotypic cues and real gay/straight people’s face cues. These studies revealed that orientation is not visible from the face—purportedly “face- based” gaydar arises from a third-variable confound. People do, however, readily infer orientation from stereotypic attributes (e.g., fashion, career). Furthermore, the folk concept of gaydar serves as a legitimizing myth: Compared to a control group, people stereotyped more when led to believe in gaydar, whereas people stereotyped less when told gaydar is an alternate label for stereotyping. Discussion focuses on the implications of the gaydar myth and why, contrary to some prior claims, stereotyping is highly unlikely to result in accurate judgments about orientation.

Thursday, September 24, 2015

Consolidating motor skills in our sleep.

It is well known that sleep, in ourselves and in other animals, helps in consolidating learned motor tasks. (When I am learning difficult passage in a new piano piece I’m preparing for performance, during initial stages of waking I observe my mind playing through the notes.) Ramanathan et al. examine the neurophysiological basis for this by recording from single motor cells in the rat brain to examine the replay of synchronous neural activity during sleep that mediates large-scale neural plasticity and stabilizes kinematics during early motor learning:
Sleep has been shown to help in consolidating learned motor tasks. In other words, sleep can induce “offline” gains in a new motor skill even in the absence of further training. However, how sleep induces this change has not been clearly identified. One hypothesis is that consolidation of memories during sleep occurs by “reactivation” of neurons engaged during learning. In this study, we tested this hypothesis by recording populations of neurons in the motor cortex of rats while they learned a new motor skill and during sleep both before and after the training session. We found that subsets of task-relevant neurons formed highly synchronized ensembles during learning. Interestingly, these same neural ensembles were reactivated during subsequent sleep blocks, and the degree of reactivation was correlated with several metrics of motor memory consolidation. Specifically, after sleep, the speed at which animals performed the task while maintaining accuracy was increased, and the activity of the neuronal assembles were more tightly bound to motor action. Further analyses showed that reactivation events occurred episodically and in conjunction with spindle-oscillations—common bursts of brain activity seen during sleep. This observation is consistent with previous findings in humans that spindle-oscillations correlate with consolidation of learned tasks. Our study thus provides insight into the neuronal network mechanism supporting consolidation of motor memory during sleep and may lead to novel interventions that can enhance skill learning in both healthy and injured nervous systems.

Wednesday, September 23, 2015

More bad things about sleep debt.

This post is to point to two recent articles on pathologies induced by sleep debt. He et al. show that sleep restriction impairs blood-brain barrier function:
The blood–brain barrier (BBB) is a large regulatory and exchange interface between the brain and peripheral circulation. We propose that changes of the BBB contribute to many pathophysiological processes in the brain of subjects with chronic sleep restriction (CSR). To achieve CSR that mimics a common pattern of human sleep loss, we quantified a new procedure of sleep disruption in mice by a week of consecutive sleep recording. We then tested the hypothesis that CSR compromises microvascular function. CSR not only diminished endothelial and inducible nitric oxide synthase, endothelin1, and glucose transporter expression in cerebral microvessels of the BBB, but it also decreased 2-deoxy-glucose uptake by the brain. The expression of several tight junction proteins also was decreased, whereas the level of cyclooxygenase-2 increased. This coincided with an increase of paracellular permeability of the BBB to the small tracers sodium fluorescein and biotin. CSR for 6 d was sufficient to impair BBB structure and function, although the increase of paracellular permeability returned to baseline after 24 h of recovery sleep. This merits attention not only in neuroscience research but also in public health policy and clinical practice.
And, Weljie et al. find cross-species molecular markers of sleep debt:
Reduced sleep duration is a hallmark of modern-day society and is increasingly associated with medical conditions, such as diabetes, obesity, metabolic syndrome, and cardiovascular disease. Here we present data from a rat model and human clinical study of chronic sleep restriction, both revealing that two metabolites in blood, oxalic acid and diacylglycerol 36:3, are quantitatively depleted under sleep-restricted conditions and restored after recovery sleep. Our findings also reveal a significant overall shift in lipid metabolism, with higher levels of phospholipids in both species and evidence of a systemic oxidative environment. This work provides a potential link between the known pathologies of reduced sleep duration and metabolic dysfunction.

Tuesday, September 22, 2015

Our nervous systems are lazy.

Selinger et al. show that the subconscious nervous processes that regulate our movement are constantly adapting to minimize the energy required for movement in a given situation. To show this, they had subjects wear robotic exoskeletons that could increase or decrease resistance to the knees, to change the difficulty of swinging the legs during walking. Within minutes, gate was adjusted to be energetically more optimal.

•People readily adapt established gait patterns to minimize energy use 
•People converge on new energetic optima within minutes, even for small cost savings 
•Updated predictions about energetically optimal gaits allow re-convergence within seconds 
•Energetic cost is not just an outcome of movement, but also continuously shapes it
People prefer to move in ways that minimize their energetic cost. For example, people tend to walk at a speed that minimizes energy use per unit distance and, for that speed, they select a step frequency that makes walking less costly. Although aspects of this preference appear to be established over both evolutionary and developmental timescales, it remains unclear whether people can also optimize energetic cost in real time. Here we show that during walking, people readily adapt established motor programs to minimize energy use. To accomplish this, we used robotic exoskeletons to shift people’s energetically optimal step frequency to frequencies higher and lower than normally preferred. In response, we found that subjects adapted their step frequency to converge on the new energetic optima within minutes and in response to relatively small savings in cost (less than 5%). When transiently perturbed from their new optimal gait, subjects relied on an updated prediction to rapidly re-converge within seconds. Our collective findings indicate that energetic cost is not just an outcome of movement, but also plays a central role in continuously shaping it.

Monday, September 21, 2015

The social mysteries of the superior temporal sulcus

Michael Beauchamp does a summary of work by Deen et al. (open access), who use functional magnetic resonance imaging (fMRI) to show a regular anterior–posterior organization in the STS for different social tasks such as theory of mind, biological motion, faces, voices and language. Here is the summary graphic:

Organization of social perception and cognition within the superior temporal sulcus (STS). Results of Deen et al. are shown on an inflated cortical surface model of the left and right hemisphere. Filled circles show the location of the peak activation, averaged across subjects, for each contrast. Colored regions show the extent of the activation for each contrast (multiple colored regions for some contrasts). 

Friday, September 18, 2015

A final musical/social at Twin Valley - some Rachmaninoff

A personal posting: On Sunday Sept. 13, Len and I hosted our last musical/social at the 1860 stone school house we have lived in for 25 years (I have been doing affairs like these since 1971-72). The following Wednesday, the Steinway B left for our Fort Lauderdale condo. The school house will be offered for sale in the spring of 2016, as we contract our Madison WI footprint to a condo near the university campus. Good friend Roy Wesley did video recordings of the concert, using a simple camera whose automatic volume control for audio damped out dynamic volume changes. I've posted these on YouTube, commentary and glitches included, just to have a record for myself and a few friends. I thought I would pass on the concert program, some pictures, an embedded video of the final Rachmaninoff  pieces, and URLS of the others, to MindBlog readers.

Chopin Nocturne in C# minor No. 18 (post.), Trois Ecossaises Op. 72 (post.) No. 3 
J. Brahms Capriccio Op 76. No 2; Waltzes, Op. 39 Nos.1, 12, 13, 14, 15. 
C. Debussy - Preludes Livre I - Danseuse de Delphes, Minstrels , Les Collines d’Anacapri 
F. Poulenc - Valse, Improvisation No. 14, Nocturne No. 2 
S.  Rachmaninoff Morceaux de fantasie (Fantasy pieces) Op. 3, No. 1, Elegie; No. 4, Polichinelle

Here is a video of the Rachmaninoff:

And URLs:
J. Brahms Capriccio Op 76. No 2; Waltzes, Op. 39 Nos.1, 12, 13, 14, 15
C. Debussy - Preludes Livre I - Danseuse de Delphes, Minstrels , Les Collines d’Anacapri 
F. Poulenc - Valse, Improvisation No. 14, Nocturne No. 2 

Thursday, September 17, 2015

Hormones and clothing choices.

Here is an interesting and curious bit from Eisenbruch et al.:
Recent evidence supports the idea that women use red clothing as a courtship tactic, and results from one study further suggested that women were more likely to wear red on days of high fertility in their menstrual cycles. Subsequent studies provided mixed support for the cycle-phase effect, although all such studies relied on counting methods of cycle-phase estimation and used between-subjects designs. By comparison, in the study reported here, we employed frequent hormone sampling to more accurately assess ovulatory timing and used a within-subjects design. We found that women were more likely to wear red during the fertile window than on other cycle days. Furthermore, within-subjects fluctuations in the ratio of estradiol to progesterone statistically mediated the within-subjects shifts in red-clothing choices. Our results appear to represent the first direct demonstration of specific hormone measurements predicting observable changes in women’s courtship-related behaviors. We also demonstrate the advantages of hormonal determination of ovulatory timing for tests of cycle-phase shifts in psychology or behavior.

Wednesday, September 16, 2015

Heritable risk of developing anxiety correlates with brain metabolism, not structure.

A group of Univ. of Wisconsin collaborators adds another installment to their series of articles on anxiety in a primate model for humans.

According to the World Health Organization, anxiety and depressive disorders are a leading source of disability, affecting hundreds of millions of people. Children can inherit an extremely anxious temperament, which is a prominent risk factor for the later development of anxiety, depression, and comorbid substance abuse. This study uses high-resolution functional and structural imaging in our well-established developmental nonhuman primate model to identify the heritable neural substrate that underlies extreme childhood anxious temperament. Using a large multigenerational family pedigree, genetic correlation analyses revealed a tripartite neural circuit where metabolism likely shares a genetic substrate with early-life dispositional anxiety. Interestingly, we found that brain function—not structure—is the critical intermediary between genetics and the childhood risk to develop stress-related psychopathology.
Understanding the heritability of neural systems linked to psychopathology is not sufficient to implicate them as intergenerational neural mediators. By closely examining how individual differences in neural phenotypes and psychopathology cosegregate as they fall through the family tree, we can identify the brain systems that underlie the parent-to-child transmission of psychopathology. Although research has identified genes and neural circuits that contribute to the risk of developing anxiety and depression, the specific neural systems that mediate the inborn risk for these debilitating disorders remain unknown. In a sample of 592 young rhesus monkeys that are part of an extended multigenerational pedigree, we demonstrate that metabolism within a tripartite prefrontal-limbic-midbrain circuit mediates some of the inborn risk for developing anxiety and depression. Importantly, although brain volume is highly heritable early in life, it is brain metabolism—not brain structure—that is the critical intermediary between genetics and the childhood risk to develop stress-related psychopathology.

Tuesday, September 15, 2015

Inventing new words - iconic sounds are used.

Perlman and collaborators find that students inventing new words use certain types of vocalizations with certain words. For example, made-up words for “up” have a rising pitch, words for “down” have a falling pitch. “Slow” has a long duration and a low pitch, whereas “fast” has a short duration and high pitch. And “smooth” has a high degree of harmonicity, whereas “rough” has a high degree of the opposite quality—noise. This suggests that vocal communication systems can originate from spontaneously created iconic characteristics of sound, just as gestural communication systems can originate from spontaneously created iconic gestures. The chart shows the data describing characteristics of words invented for 18 contrasting ideas: up, down, big, small, good, bad, fast, slow, far, near, few, many, long, short, rough, smooth, attractive, and ugly.

The plots show the acoustic characteristics of each of the 18 meanings. The five variables are represented on the x-axis: D, duration; H, harmonics to noise ratio; I, intensity; P, pitch; C, pitch change. All values are normalized (z-scored) for each of the five measures. The red line shows the median and the blue box spans the first and third quartiles. The up and down arrows indicate variables that differed reliably between antonymic meanings. For example, vocalizations for bad differed from those for good by having a lower harmonics to noise ratio and pitch. The variables marked with arrows were the basis for the iconic template of each meaning.

Monday, September 14, 2015

Brain correlates of learning character traits versus rewards.

Hsu and Jenkins summarize work of Hackel et al. showing where our brains learn about traits versus rewards.
In a functional magnetic resonance imaging (fMRI) study..., Hackel et al use an innovative combination of ideas and tools from social psychology, economics and cognitive neuroscience, they offer neural evidence that associative learning processes are involved in making inferences about traits. Specifically, the authors conducted a study in which participants interacted repeatedly with eight different partners: four purported human participants and four slot machines. On each trial, participants chose to interact with one of two human (or slot machine) counterparts. The chosen counterpart, who had been endowed with a certain number of points on that trial, then shared some proportion of those points with the participant. Critically, targets varied orthogonally in terms of the average magnitude of their starting endowment (reward) and the average proportion of the endowment that was shared with the participant (generosity), enabling the authors to dissociate signals associated with trait learning from those associated with reward processing.
Consistent with the idea that trait learning engages associative learning processes, BOLD (blood oxygen level-dependent) responses of the ventral striatum during an initial training phase were predicted by an associative learning model that captures both reward and trait information. Moreover, two pieces of evidence support the idea that participants were able to make use of this trait information in a manner described by psychological theories of trait attribution. First, in a test phase in which participants knew each potential partner's starting endowment, participants chose interaction partners on the basis of those partners' past levels of generosity, and the extent to which they did so was associated with activity in the ventromedial prefrontal cortex (see figure). In addition, participants exhibited a tendency to generalize these generosity attributions, preferring the more generous targets when asked to pick a collaborator for a new, cooperative task-a hallmark of trait attribution.

Figure: Learning about traits versus rewards.  In an fMRI study, participants interacted with partners who varied in reward (the absolute amount of money shared with the participant) and generosity (the proportion shared). Activity in the ventromedial prefrontal cortex (vmPFC) was associated with preferring more generous targets, even when those targets shared less money in absolute terms.

Friday, September 11, 2015

Thinking too much - Self generated thought as the engine of neuroticism.

Perkins et al. offer an opinion piece in which they propose that the cost and benefits of neuroticism are surface manifestations of a tendency to engage in negatively hued self generated thought. I pass on their abstract and text from one of their figures:
•Existing neuroticism models cannot explain its link to both unhappiness and creativity. 
•Self-generated thought (SGT) facilitates creativity but can cause unhappiness. 
•Threat-related regions of medial prefrontal cortex (mPFC) generate blue-tinted SGT. 
•High neuroticism may reflect proneness to SGT arising from mPFC hyperactivity. 
Neuroticism is a dimension of personality that captures trait individual differences in the tendency to experience negative thoughts and feelings. Established theories explain neuroticism in terms of threat sensitivity, but have limited heuristic value since they cannot account for features of neuroticism that are unrelated to threat, such as creativity and negative psychological states experienced in benign, threat-free environments. We address this issue by proposing that neuroticism stems from trait individual differences in activity in brain circuits that govern the nature of self-generated thought (SGT). We argue our theory explains not only the association of neuroticism with threat sensitivity but also the prominence within the neurotic mind of representations of information that are unrelated to the way the world is right now, such as creativity and nonsituational ‘angst’.
A figure legend from the text (graphics did not have resolution adequate to display here):

Neuroticism, self-generated thought (SGT) and perceptions of threat intensity. (A) If an individual with ventromedial prefrontal cortex (vmPFC)/basolateral nuclei of the amygdala (BLA) that is twice as reactive as that of the average person switches from anxiety to panic when a spider encroaches within 4 m (an early switcher), then an average person will switch from anxiety to panic only when that same spider encroaches within 2 m (an ‘average switcher’). Conversely, a person with vmPFC/BLA that is half as reactive as that of the average person will switch from anxiety to panic only when that same spider encroaches within 1 m (a ‘late switcher’). The same psychological state (panic) is achieved in each individual, but the physical distance to threat that elicits it is different. (The graphic showed approaching spider.)(B) A model of how neuroticism is driven by individual differences in susceptibility to negatively hued SGT. Individuals who happen to have greater spontaneous activity in regions of mPFC associated with threat perception, experience frequent, spontaneous activation of threat-related amygdala circuits in situations that are wholly nonthreatening. (The graphic was picture of flowers.) In individuals who also happen to have a highly reactive vmPFC/BLA, these activations are likely to be sufficiently intense to be debilitating; therefore, such individuals present as being highly neurotic.

Thursday, September 10, 2015

Savoring happy memories - value representations in the striatum

Speer et al. observe responses in the corticostriatal circuits that respond to monetary reward when positive autobiographical memories are recalled. These response "may be adaptive for regulating positive emotion and promoting better well-being."

•The act of recalling positive life events enhances emotion and has tangible value
•Corticostriatal fMRI signals index emotion evoked by recalling positive life events
•Striatal activity relates to positive mood enhancing effects of reminiscing
•Striatal responses to positive memories may relate to individual resilience 
Reminders of happy memories can bring back pleasant feelings tied to the original experience, suggesting an intrinsic value in reminiscing about the positive past. However, the neural circuitry underlying the rewarding aspects of autobiographical memory is poorly understood. Using fMRI, we observed enhanced activity during the recall of positive relative to neutral autobiographical memories in corticostriatal circuits that also responded to monetary reward. Enhanced activity in the striatum and medial prefrontal cortex was associated with increases in positive emotion during recall, and striatal engagement further correlated with individual measures of resiliency. Striatal response to the recall of positive memories was greater in individuals whose mood improved after the task. Notably, participants were willing to sacrifice a more tangible reward, money, in order to reminisce about positive past experiences. Our findings suggest that recalling positive autobiographical memories is intrinsically valuable, which may be adaptive for regulating positive emotion and promoting better well-being.

Wednesday, September 09, 2015

Convergent evolution of numerosity detection in bird and primate brains.

From Ditz and Nieder:
Birds are known for their advanced numerical competence, although a six-layered neocortex that is thought to enable primates with the highest levels of cognition is lacking in birds. We recorded neuronal activity from an endbrain association area termed nidopallium caudolaterale (NCL) in crows that discriminated the number of items in displays. NCL neurons were tuned to preferred numerosities. Neuronal discharges were relevant for the crows’ correct performance. Both the neuronal and the behavioral tuning functions were best described on a logarithmic number line, just as predicted by the psychophysical Weber–Fecher Law. The behavioral and neuronal numerosity representations in the crow reflect surprisingly well those found in the primate association cortex. This finding suggests that distantly related vertebrates with independently developed endbrains adopted similar neuronal solutions to process quantity - convergent evolution of a superior solution to a common computational problem.

Tuesday, September 08, 2015

A classification of cognitive mechanisms in meditation practice.

Dahl, Lutz, and Davidson offer an interesting classification system for different styles of meditation. Here is a paste up from their abstract and introduction:
Scientific research highlights the central role of specific psychological processes, in particular those related to the self, in various forms of human suffering and flourishing. This view is shared by Buddhism and other contemplative and humanistic traditions, which have developed meditation practices to regulate these processes. Building on a previous paper in this journal, we propose a novel classification system that categorizes specific styles of meditation into attentional, constructive, and deconstructive families based on their primary cognitive mechanisms. According to this model, the primary cognitive mechanisms in these three families are: (i) attention regulation and meta-awareness; (ii) perspective taking and reappraisal; and (iii) self-inquiry, respectively. To illustrate the role of these processes in different forms of meditation, we discuss how experiential fusion, maladaptive self-schema, and cognitive reification are differentially targeted by these processes in the context of Buddhist meditation, integrating the perspectives of other contemplative, philosophical, and clinical perspectives when relevant. The mechanisms and targets we propose are drawn from cognitive science and clinical psychology. Although these psychological processes are theoretically complex, as are the meditation practices that target them, we propose this novel framework as a first step in identifying specific cognitive mechanisms to aid in the scientific study of different families of meditation and the impact of these practices on well-being.
This article appears to be open source, and well worth reading for those interested in meditation. (I can send full text to motivated readers who have difficulty securing the full text.) I thought I would pass on just one edited clip from the section on the constructive family of meditation practices:
One of the most widely studied practices in the constructive family is the cultivation of compassion. Compassion training is held to alter core self-related processes, initiating a shift from self-oriented cognitive, affective, and behavioral patterns to patterns that are oriented toward the well-being of others...Research into the neural correlates of empathy has found that similar regions, including the insula, the anterior and mid-cingulate cortices, and the supplementary motor area, are activated across various forms of empathy...By way of contrast, compassion is linked to regions associated with reward, positive affect, and feelings of affection, such as the ventral striatum and medial orbitofrontal cortex...Studies of compassion training have also found increased activation in regions associated with executive function, including the dorsolateral prefrontal cortex and the anterior cingulate cortex...these preliminary findings suggest that cultivating compassion strengthens multiple networks, each of which may affect distinct psychological processes and thereby contribute to well-being in different ways.
Empathy and compassion also affect the peripheral biology of the human body. Perceiving stress in another individual has been linked to elevated cortisol levels, a relation that is more robust in those with high trait empathy, whereas compassion has been linked to lower levels of cortisol reactivity. Preliminary studies of compassion training have found associations between the amount of time spent engaging in compassion training and inflammatory biomarkers, with more compassion training leading to decreased levels of both C-reactive protein and interleukin 6. These findings suggest that the mind can be trained to orient itself toward the well-being of others and that this shift from self- to other-orientation impacts both the brain and the peripheral biology of the body and, in particular, the way the body responds to environmental stressors. Further research is required to elucidate the precise mechanisms through which these states affect the body, and also to investigate how changes in peripheral biology reciprocally impact psychological processes and the relationship between these processes and well-being.