Category: Brain

biological, Brain, Magic

Massive Comparison Of Narrative Accounts Finds Ketamine Trips Are Remarkably Similar to Near Death Experiences (NDEs), Supporting The Neurochemical Model Of NDEs
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Similarity in the most frequently used words in accounts of near death experiences (NDE) and ketamine trips, via Martial et al, 2019

By Christian Jarrett

First-hand accounts of what it is like to come close to death often contain the same recurring themes, such as the sense of leaving the body, a review of one’s life, tunnelled vision and a magical sense of reality. Mystics, optimists and people of religious faith interpret this as evidence of an after life. Sceptically minded neuroscientists and psychologists think there may be a more terrestrial neurochemical explanation – that the profound and magical near death experience is caused by the natural release of brain chemicals at or near the end of life.

Supporting this, observers have noted the striking similarities between first-hand accounts of near-death experiences and the psychedelic experiences described by people who have taken mind-altering drugs.

“I had the feeling of floating, still tied to the remains of my heavy body, but floating nonetheless. I rocked and moved, at times as if on a liquid, undulating surface, at other times rising upwards, like a helium-filled flat container.” Excerpt from Amazing First-time Experience in the K-hole, published by Phaeton at the Erowid Experience vaults.

Perhaps, near death, the brain naturally releases the same psychoactive substances as used by drug takers, or substances that act on the same brain receptors as the drugs. It’s also notable that psychedelic drugs have been taken by the shamans of traditional far-flung cultures through history as a way to, as they see it, visit the after world or speak to the dead.

To date, however, much of the evidence comparing near death experiences and psychedelic trips has been anecdotal or it’s been based on questionnaire measures that arguably struggle to capture the complexity of these life-changing experiences. Pursuing this line of enquiry with a new approach, an international team of researchers led by Charlotte Martial at the University Hospital of Liège has conducted a deep lexical analysis, comparing 625 written narrative accounts of near death experiences with more than 15,000 written narrative accounts of experiences taking psychoactive drugs (sourced from the Erowid Experience vaults), including 165 different substances in 10 drug classes.

Continue reading “Massive Comparison Of Narrative Accounts Finds Ketamine Trips Are Remarkably Similar to Near Death Experiences (NDEs), Supporting The Neurochemical Model Of NDEs” →

Brain

Young Adults With Better Navigation Skills Do Not Have Larger Hippocampi, Raising Questions About The Meaning Of The Famous Taxi Driver Studies

GettyImages-165671507.jpgBy Christian Jarrett

The famous studies of London’s taxi drivers – showing they have larger hippocampi (the comma-shaped brain structure in the temporal lobes) than controls – have become a staple of undergrad psychology courses and a classic example of how your brain changes according to what you do with it. Many other studies have also implied an association between hippocampal size and navigational ability – for instance, people with Alzheimer’s, who have lost neurons in this brain structure, tend to experience problems finding their way around. For some time, then, an obvious, though tentative, inference has been that better navigators have bigger hippcampi, with London taxi drivers (and their mastery of “the knowledge” of the city’s convoluted streets) and people with Alzheimer’s representing opposite extremes of the spectrum. However, a new study, released as a preprint at bioRxiv, raises questions about how far we can safely generalise from the taxi driver and Alzheimer’s-based research.

Steven Weisberg and his colleagues tested young adults’ navigation skills and assessed the size of their hippocampi and found the two were not significantly correlated. “The hippocampus plays a crucial role in spatial navigation in humans, but the volume of the hippocampus may not be a biological marker for navigation ability among typical populations,” the researchers concluded.

Continue reading “Young Adults With Better Navigation Skills Do Not Have Larger Hippocampi, Raising Questions About The Meaning Of The Famous Taxi Driver Studies” →

Brain, Methods, Replications

Widely Used Neuroimaging Analyses Allow Almost Any Result To Be Presented As A Successful Replication, Paper Claims
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Of 135 surveyed fMRI papers that contained claims of replicating previous findings, over 40 per cent did not consider peak activity levels within brain regions – a flawed approach that allows almost any result to be claimed as a successful replication (from YongWooK Hong et al, 2019)

By Matthew Warren

As the list of failed replications continues to build, psychology’s reproducibility crisis is becoming harder to ignore. Now, in a new paper that seems likely to ruffle a few feathers, researchers suggest that even many apparent successful replications in neuroimaging research could be standing on shaky ground.  As the paper’s title bluntly puts it, the way imaging results are currently analysed “allows presenting anything as a replicated finding.” 

The provocative argument is put forward by YongWook Hong from Sungkyunkwan University in South Korea and colleagues, in a preprint posted recently to bioRxiv. The fundamental problem, say the researchers, is that scientists conducting neuroimaging research tend to make and test hypotheses with reference to large brain structures. Yet neuroimaging techniques, particularly functional magnetic resonance imaging (fMRI), gather data at a much more fine-grained resolution. 

This means that strikingly different patterns of brain activity could produce what appears to be the same result. For example, one lab might find that a face recognition task activates the amygdala (a structure found on each side of the brain that’s involved in emotional processing). Later, another lab apparently replicates this finding, showing activation in the same structure during the same task. But the amygdala contains hundreds of individual “voxels”, the three-dimensional pixels that form the basic unit of fMRI data. So the second lab could have found activity in a completely different part of the amygdala, yet it would appear that they had replicated the original result. 

Continue reading “Widely Used Neuroimaging Analyses Allow Almost Any Result To Be Presented As A Successful Replication, Paper Claims” →

Brain, Developmental, Memory

Young Children With Thinner Brain Regions Have Better Working Memory
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Associations between the thickness of different cortical areas and children’s age and working memory (digit span); via Botdorf & Riggins, 2018

By Matthew Warren

Anyone who has stood in the supermarket aisle trying to remember their shopping list might have wished for a larger brain. But when it comes to memory, bigger isn’t always better. A study published in Neuropsychologia has found that young children whose cerebral cortex is thinner in certain areas also tend to have better working memory.

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Brain, guest blogger, Mental health

Participants In This Study Successfully Down-regulated Their Amygdala Activity With The Help Of Neurofeedback
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The blue bars show reduced amygdala activity in the group that received real-time neural feedback while looking at negative images; from Herwig et al, 2019

 By guest blogger Eleanor Morgan

Interventions like cognitive behavioural therapy help people better control their emotions by teaching them new ways of thinking. A recent study published in NeuroImage suggests this approach could be augmented by using “neurofeedback” to help regulate activity in a key brain structure – the amygdala.

Continue reading “Participants In This Study Successfully Down-regulated Their Amygdala Activity With The Help Of Neurofeedback” →

Brain, Sleep and dreaming

Rock-A-Bye Adult – Study Shows Grown-ups Enjoy Better Sleep And Memory Consolidation In A Rocking Bed

giphyBy Emma Young

As every parent knows, gentle rocking helps a baby to fall asleep. Now a new study, published in Current Biology by researchers in Switzerland, shows that a rocking bed also benefits adults, extending the time that they spend in deep, slow-wave sleep, helping them sleep more soundly, and increasing their memory consolidation through the night. A related rocking study on mice, conducted by a team involving some of the same researchers, and published in the same journal issue, helps to reveal how rocking might have these effects. 

Continue reading “Rock-A-Bye Adult – Study Shows Grown-ups Enjoy Better Sleep And Memory Consolidation In A Rocking Bed” →

Brain, Sport

A Surprising New Way To Avoid Choking Under Pressure – Imagine You Have The Prize And Are Performing To Keep It

By Christian Jarrett

Choking is a ubiquitous and extremely frustrating human weakness – as the stakes are raised, our performance usually improves, but only up to a point, beyond which the pressure gets too much and our skills suddenly deteriorate. Any new psychological tricks to ameliorate this problem will be welcomed by sports competitors, students and anyone else who needs to be at their best under high pressure situations.

A fascinating paper in Social Cognitive and Affective Neuroscience documents a new technique for reducing choking that has to do with altering how you look at what is at stake. Moreover, the research shows how this act of reappraisal is reflected in altered activity in a key brain area that’s previously been implicated in how well we can maintain our fine motor control under pressure.

Continue reading “A Surprising New Way To Avoid Choking Under Pressure – Imagine You Have The Prize And Are Performing To Keep It” →

Brain, Psychosis

New Findings “Lend Confidence” To The Idea That Cortical Blindness Eliminates The Risk Of Developing Schizophrenia
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Not a single case of schizophrenia has ever been reported in someone who is cortically blind, according to the authors of a new population-wide study into the phenomenon

By Emma Young

Various visual impairments and abnormalities, such as unusual eye movement patterns, blink rates and retinal problems, are more common than usual in people diagnosed with schizophrenia, suggesting these issues may contribute to the development of the condition. Yet paradoxically, since the 1950s, there have also been intriguing hints that people who are blind from birth or an early age are less likely to develop schizophrenia and other kinds of psychoses, suggesting blindness can act as a protective factor against the illness. 

Before now, findings – mostly from case-study type research – suggested that cortical blindness (resulting from abnormalities in the occipital cortex of the brain, rather than the eyes) may even be completely protective. As far as the authors of a new study are aware, not a single case of schizophrenia has ever been reported in someone who is cortically blind. 

“Note that most authors are cautious to add that ‘absence of evidence is not evidence of absence’,” Vera Morgan at the University of Western Australia told me. But a total of zero documented cases among such people to date is striking.

Morgan is the lead author of the first large-scale population study investigating this phenomenon, published in Schizophrenia Research, and it provides further evidence that blindness really does reduce – or even eliminate – the risk of developing schizophrenia.

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Brain, Developmental, Educational

Time For A Fresh Approach To Learning Difficulties? The Cognitive Profile Of Kids Struggling At School Bore No Relation To Their Official Diagnoses
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The study used “machine learning” to organise children into clusters based on their cognitive profiles. (Figure 4 reproduced from Astle et al, 2018. See their open-access paper for description.)

By Emma Young

Around 30 per cent of British children fail to meet expected targets in reading or maths at age 11. These children face a future of continuing difficulties in education, as well as poorer mental health and employment success. Understanding why some kids struggle – and providing them with tailored support as early as possible – is clearly vital. Some will be diagnosed with a specific disorder, such as Attention Deficient Hyperactivity Disorder or dyslexia, and get targeted help. But many will not. And even many conventional diagnostic labels may be misleading, and fail to capture the true picture of a child’s problems, according to new work by a team at the MRC Cognition and Brain Sciences Unit at the University of Cambridge, which has come up with a radical, alternative approach. 

Continue reading “Time For A Fresh Approach To Learning Difficulties? The Cognitive Profile Of Kids Struggling At School Bore No Relation To Their Official Diagnoses” →

Brain, Personality

People With Advantageous Personality Traits Have More Nerve-Fibre Insulation (Myelination) In Key Brain Areas
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(a) A post-mortem map of average myelination intensity in the brain created over a century ago (red areas show greater myelin). (b) new estimates of average myelin distribution using brain scan technology (independent of personality, red shows greatest myelination, blue the least). From Toschi and Passamonti, 2018

By Christian Jarrett

Researchers are getting closer to understanding the neurological basis of personality. For a new paper in the Journal of Personality, Nicola Toschi and Luca Passamonti took advantage of a recent technological breakthrough that makes it possible to use scans to estimate levels of myelination in different brain areas (until fairly recently this could only be done at postmortem).

Myelin is a fatty substance that insulates nerve fibres and speeds up information processing in the brain – it tends to be thicker in parts of the cortex involved in movement and perception, while it is lighter in brain regions that evolved later and that are involved in more abstract thought and decision making.

The new findings, though preliminary, suggest that people with “healthier”, more advantageous, personality traits, such as more emotional stability and greater conscientiousness, may benefit during development from more enhanced myelination in key areas of the brain where the myelination process is particularly prolonged in humans, continuing through adolescence and into the twenties.

Continue reading “People With Advantageous Personality Traits Have More Nerve-Fibre Insulation (Myelination) In Key Brain Areas” →