Monday, October 21, 2019

Shape of your heart is determined by whether you run or sit.

Shave et al. show that endurance runners and farmers have larger, elongated left ventricles with thin walls (traits that help pump large volumes of blood for a long time) compared with football linemen, whose training emphasizes short, high-intensity exercise. Linemen, as well has sedentary people, have shorter, wider ventricles with thicker walls and are more prone to hypertensive heart disease. Their experiments used ultrasound imaging to examine the hearts of more than 160 adult men from four groups: long-distance runners, sedentary adults, highly trained football linemen, and the Tarahumara, Native American farmers renowned for their running ability.

Abstract
Chimpanzees and gorillas, when not inactive, engage primarily in short bursts of resistance physical activity (RPA), such as climbing and fighting, that creates pressure stress on the cardiovascular system. In contrast, to initially hunt and gather and later to farm, it is thought that preindustrial human survival was dependent on lifelong moderate-intensity endurance physical activity (EPA), which creates a cardiovascular volume stress. Although derived musculoskeletal and thermoregulatory adaptations for EPA in humans have been documented, it is unknown if selection acted similarly on the heart. To test this hypothesis, we compared left ventricular (LV) structure and function across semiwild sanctuary chimpanzees, gorillas, and a sample of humans exposed to markedly different physical activity patterns. We show the human LV possesses derived features that help augment cardiac output (CO) thereby enabling EPA. However, the human LV also demonstrates phenotypic plasticity and, hence, variability, across a wide range of habitual physical activity. We show that the human LV’s propensity to remodel differentially in response to chronic pressure or volume stimuli associated with intense RPA and EPA as well as physical inactivity represents an evolutionary trade-off with potential implications for contemporary cardiovascular health. Specifically, the human LV trades off pressure adaptations for volume capabilities and converges on a chimpanzee-like phenotype in response to physical inactivity or sustained pressure loading. Consequently, the derived LV and lifelong low blood pressure (BP) appear to be partly sustained by regular moderate-intensity EPA whose decline in postindustrial societies likely contributes to the modern epidemic of hypertensive heart disease.

Friday, October 18, 2019

The default mode network represents esthetic appeal.

Vessel et al. note another role for the default mode network of our brain:

Significance
Despite being highly subjective, aesthetic experiences are powerful moments of interaction with one’s surroundings, shaping behavior, mood, beliefs, and even a sense of self. The default-mode network (DMN), which sits atop the cortical hierarchy and has been implicated in self-referential processing, is typically suppressed when a person engages with the external environment. Yet not only is the DMN surprisingly engaged when one finds a visual artwork aesthetically moving, here we present evidence that the DMN also represents aesthetic appeal in a manner that generalizes across visual aesthetic domains, such as artworks, landscapes, or architecture. This stands in contrast to ventral occipitotemporal cortex (VOT), which represents the content of what we see, but does not contain domain-general information about aesthetic appeal.
Abstract
Visual aesthetic evaluations, which impact decision-making and well-being, recruit the ventral visual pathway, subcortical reward circuitry, and parts of the medial prefrontal cortex overlapping with the default-mode network (DMN). However, it is unknown whether these networks represent aesthetic appeal in a domain-general fashion, independent of domain-specific representations of stimulus content (artworks versus architecture or natural landscapes). Using a classification approach, we tested whether the DMN or ventral occipitotemporal cortex (VOT) contains a domain-general representation of aesthetic appeal. Classifiers were trained on multivoxel functional MRI response patterns collected while observers made aesthetic judgments about images from one aesthetic domain. Classifier performance (high vs. low aesthetic appeal) was then tested on response patterns from held-out trials from the same domain to derive a measure of domain-specific coding, or from a different domain to derive a measure of domain-general coding. Activity patterns in category-selective VOT contained a degree of domain-specific information about aesthetic appeal, but did not generalize across domains. Activity patterns from the DMN, however, were predictive of aesthetic appeal across domains. Importantly, the ability to predict aesthetic appeal varied systematically; predictions were better for observers who gave more extreme ratings to images subsequently labeled as “high” or “low.” These findings support a model of aesthetic appreciation whereby domain-specific representations of the content of visual experiences in VOT feed in to a “core” domain-general representation of visual aesthetic appeal in the DMN. Whole-brain “searchlight” analyses identified additional prefrontal regions containing information relevant for appreciation of cultural artifacts (artwork and architecture) but not landscapes.

Wednesday, October 16, 2019

Cross-national negativity bias in reacting to news

There seems to be a world-wide anxiety industry of media that find maximum profits in presenting mostly negative news - in a way similar to the drug companies that have reaped great profits from flooding distressed population areas with opioids. An interesting study in this area comes from Soroka et al., who provide more information on our human tendency to react more strongly to negative than positive information. (See also my post on Pinker's "Enlightenment Now" book that engages this topic):
What accounts for the prevalence of negative news content? One answer may lie in the tendency for humans to react more strongly to negative than positive information. “Negativity biases” in human cognition and behavior are well documented, but existing research is based on small Anglo-American samples and stimuli that are only tangentially related to our political world. This work accordingly reports results from a 17-country, 6-continent experimental study examining psychophysiological reactions to real video news content. Results offer the most comprehensive cross-national demonstration of negativity biases to date, but they also serve to highlight considerable individual-level variation in responsiveness to news content. Insofar as our results make clear the pervasiveness of negativity biases on average, they help account for the tendency for audience-seeking news around the world to be predominantly negative. Insofar as our results highlight individual-level variation, however, they highlight the potential for more positive content, and suggest that there may be reason to reconsider the conventional journalistic wisdom that “if it bleeds, it leads.”

Monday, October 14, 2019

An update on the science of ‘free will’

I want to point to an excellent article by Gholilpour in the Atlantic Magazine that describes a reinterpretation of experiments by Libet taken to suggest that our brains 'decide' to initiate a movement before our subjective awareness of intending to initiate that movement. A 'readiness potential' is observed about 500 msec before an action occurs, while a subject reports initiating that action about 150 msec before it occurs. Gholilpour points to work of Schurger and colleagues that suggests that the readiness potential is not the mark of a brain's brewing intention, but something much more circumstantial.
...Schurger and his colleagues ... proposed an explanation. Neuroscientists know that for people to make any type of decision, our neurons need to gather evidence for each option. The decision is reached when one group of neurons accumulates evidence past a certain threshold. Sometimes, this evidence comes from sensory information from the outside world: If you’re watching snow fall, your brain will weigh the number of falling snowflakes against the few caught in the wind, and quickly settle on the fact that the snow is moving downward.
Libet’s experiment, Schurger pointed out, provided its subjects with no such external cues. To decide when to tap their fingers, the participants simply acted whenever the moment struck them. Those spontaneous moments, Schurger reasoned, must have coincided with the haphazard ebb and flow of the participants’ brain activity. They would have been more likely to tap their fingers when their motor system happened to be closer to a threshold for movement initiation.
This would not imply, as Libet had thought, that people’s brains “decide” to move their fingers before they know it. Hardly. Rather, it would mean that the noisy activity in people’s brains sometimes happens to tip the scale if there’s nothing else to base a choice on, saving us from endless indecision when faced with an arbitrary task. The readiness potential would be the rising part of the brain fluctuations that tend to coincide with the decisions. This is a highly specific situation, not a general case for all, or even many, choices.
The name Schurger rang a bell with me, and so I did a MindBlog search, only to discover that I had reported Schurger's work in a 2016 post "A 50 year misunderstanding of how we decide to initiate action - our intuition is valid". I then proceeded to completely forget about it when I was preparing a subsequent 2019 lecture mentioning Libet's work. The conventional dogma that we are 'late to action' was apparently burned into my brain - most embarrassing. (I've now inserted the new perspective into four of my web lectures, dating as far back as 2012). The real clincher is...
In a new study under review for publication in the Proceedings of the National Academy of Sciences, Schurger and two Princeton researchers repeated a version of Libet’s experiment. To avoid unintentionally cherry-picking brain noise, they included a control condition in which people didn’t move at all. An artificial-intelligence classifier allowed them to find at what point brain activity in the two conditions diverged. If Libet was right, that should have happened at 500 milliseconds before the movement. But the algorithm couldn’t tell any difference until about only 150 milliseconds before the movement, the time people reported making decisions in Libet’s original experiment.
In other words, people’s subjective experience of a decision—what Libet’s study seemed to suggest was just an illusion—appeared to match the actual moment their brains showed them making a decision.
Gholilpour points out that this does not resolve the question of free will, it only deepens the question, which is the subject of an intensive collaboration between neuroscientists and philosophers, backed by $7 million from two private foundations, the John Templeton Foundation and the Fetzer Institute.

Friday, October 11, 2019

More critique of work linking loving kindness meditation and cellular again

In my Sept. 23 post, "Loving kindness meditation slows cellular aging?", I gave a few of the reasons that the article triggered my bullshit detector. A email from Harris Friedman, Univ. of Florida, has pointed me to their more extended critique in a letter to the editor of Psychoneuroendocrinology, which I pass on in a slightly truncated version:
Extraordinary claims require compelling evidence: Concerns about “loving-kindness meditation slows biological aging in novices”
The recent paper by Le Nguyen et al. (2019) makes the extra- ordinary claim that loving-kindness meditation (LKM) slows biological aging. Unfortunately, its headline-grabbing title lacks compelling evidence. This paper shows telomere length (TL) decreased considerably in a control group over a very short time period, as compared to a LKM group, while a mindfulness meditation (MM) group was somewhere in between. From this difference, the paper argues that LKM slows biological aging, which is quite a logical leap. Clearly LKM had nothing to do with the extent of TL shrinkage in the control group, and why the control group’s TL decreased so much is ignored in the paper. More generally, there are many problems with using TL as a proxy for biological aging. Even if this paper’s basic logic is accepted, there are many problems with how the paper’s data are handled.1 The most important problem is the absence of any analyses that provides a direct and straightforward examination of pre-post TL as a function of experimental condition. Consequently, we ran a 2×3 mixed factorial ANOVA using TL measured across two times (pre and post) compared across three conditions (control, MM, and LKM) with the paper’s data. Although a significant repeated measures main effect was found, the interaction with experimental condition was non-sig- nificant. One-way ANOVAs examining pre-, post-, and change/differ- ence TL variables as a function of condition also produced non-sig nificant results. Looking at the data using other statistical approaches, however, did show some pattern of mixed results that trend, although most are non-significant, in the direction of the LKM group having less TL shortening compared to the other groups. Regardless of analysis, effect sizes were consistently meager.
In addition, there are several serious confounds compromising any valid comparison among the groups. For example, the data show that six in the control group engaged in some meditation, and one even reported meditating 16 days during the study’s short time-span. This hardly constitutes an adequate control group for a meditation study. Also, the LKM group spent considerably more time meditating than the MM group, so these did not differ only in meditation type. We are unable to address many other problems with this paper due to this journal’s length restrictions in a letter to the editor. We simply conclude that this paper’s extraordinary claim does not have the compelling evidence to back it up, and we urge not making extraordinary claims without such evidence. 
Harris L. Friedman - University of Florida, United States
Douglas A. MacDonald - University of Detroit Mercy, United States
Nicholas J.L. Brown-  University of Groningen, the Netherlands
James C. Coyne University of Pennsylvania, United States

Wednesday, October 09, 2019

Psilocybin + Mindfulness Meditation change brain connectivity - lasting positive effects

Dolan points to work by Smigielski et al.:
Both psychedelics and meditation exert profound modulatory effects on consciousness, perception and cognition, but their combined, possibly synergistic effects on neurobiology are unknown. Accordingly, we conducted a randomized, double-blind, placebo-controlled study with 38 participants following a single administration of the psychedelic psilocybin (315 μg/kg p.o.) during a 5-day mindfulness retreat. Brain dynamics were quantified directly pre- and post-intervention by functional magnetic resonance imaging during the resting state and two meditation forms. The analysis of functional connectivity identified psilocybin-related and mental state–dependent alterations in self-referential processing regions of the default mode network (DMN). Notably, decoupling of medial prefrontal and posterior cingulate cortices, which is thought to mediate sense of self, was associated with the subjective ego dissolution effect during the psilocybin-assisted mindfulness session. The extent of ego dissolution and brain connectivity predicted positive changes in psycho-social functioning of participants 4 months later. Psilocybin, combined with meditation, facilitated neurodynamic modulations in self-referential networks, subserving the process of meditation by acting along the anterior–posterior DMN connection. The study highlights the link between altered self-experience and subsequent behavioral changes. Understanding how interventions facilitate transformative experiences may open novel therapeutic perspectives. Insights into the biology of discrete mental states foster our understanding of non-ordinary forms of human self-consciousness and their concomitant brain substrate.

Monday, October 07, 2019

Mindfulness doesn't reduce impulsive behavior.

Korponay, Davidson and colleagues present results of a study that were contrary to their expectation that the practice of mindfulness meditation would correlate with a reduction in impulsive behaviors (like having that second dish of ice cream). What they found is that neither short-term nor long-term meditation appears to be effective for reducing impulsivity that is not related to attentional difficulties, but rather is a function of motor control and planning capacities. Here is their detailed abstract:
Interest has grown in using mindfulness meditation to treat conditions featuring excessive impulsivity. However, while prior studies find that mindfulness practice can improve attention, it remains unclear whether it improves other cognitive faculties whose deficiency can contribute to impulsivity. Here, an eight-week mindfulness intervention did not reduce impulsivity on the go/no-go task or Barratt Impulsiveness Scale (BIS-11), nor produce changes in neural correlates of impulsivity (i.e. frontostriatal gray matter, functional connectivity, and dopamine levels) compared to active or wait-list control groups. Separately, long-term meditators (LTMs) did not perform differently than meditation-naïve participants (MNPs) on the go/no-go task. However, LTMs self-reported lower attentional impulsivity, but higher motor and non-planning impulsivity on the BIS-11 than MNPs. LTMs had less striatal gray matter, greater cortico-striatal-thalamic functional connectivity, and lower spontaneous eye-blink rate (a physiological dopamine indicator) than MNPs. LTM total lifetime practice hours (TLPH) did not signifcantly relate to impulsivity or neurobiological metrics. Findings suggest that neither short nor long-term mindfulness practice may be efective for redressing impulsive behavior derived from inhibitory motor control or planning capacity defcits in healthy adults. Given the absence of TLPH relationships to impulsivity or neurobiological metrics, diferences between LTMs and MNPs may be attributable to pre-existing diferences.

Friday, October 04, 2019

Gender and race stereotypes - what's in a name...

Eaton et al. give us more data on the application of gender and race stereotypes in academia:
The current study examines how intersecting stereotypes about gender and race influence faculty perceptions of post-doctoral candidates in STEM fields in the United States. Using a fully-crossed, between-subjects experimental design, biology and physics professors (n = 251) from eight large, public, U.S. research universities were asked to read one of eight identical curriculum vitae (CVs) depicting a hypothetical doctoral graduate applying for a post-doctoral position in their field, and rate them for competence, hireability, and likeability. The candidate’s name on the CV was used to manipulate race (Asian, Black, Latinx, and White) and gender (female or male), with all other aspects of the CV held constant across conditions. Faculty in physics exhibited a gender bias favoring the male candidates as more competent and more hirable than the otherwise identical female candidates. Further, physics faculty rated Asian and White candidates as more competent and hirable than Black and Latinx candidates, while those in biology rated Asian candidates as more competent and hirable than Black candidates, and as more hireable than Latinx candidates. An interaction between candidate gender and race emerged for those in physics, whereby Black women and Latinx women and men candidates were rated the lowest in hireability compared to all others. Women were rated more likeable than men candidates across departments. Our results highlight how understanding the underrepresentation of women and racial minorities in STEM requires examining both racial and gender biases as well as how they intersect.

Wednesday, October 02, 2019

Cognitive and Affective Neuroscience

I want to point the subset of MindBlog readers interested in brain-behavior correlations to the journal “Social Cognitive and Affective Neuroscience,” particularly to the June 2019 issue. Most of the articles in this issue are open source, and a scan of the article abstracts gives a good sense of the kind of work being done in this field to identify correlations between behaviors and brain activities in different brain areas. Such work gives us an idea of where to focus our attention when extreme behaviors are at issue, such as (in the first article) being willing to fight and die for a cause. Another interesting article suggests that the medial prefrontal cortex may play a role in maintaining a positively biased self-concept.