At the root of post-traumatic stress disorder, or PTSD, is a memory that cannot be controlled. It may intrude on everyday activity, thrusting a person into the middle of a horrifying event, or surface as night terrors or flashbacks. Decades of treatment of military veterans and sexual assault survivors have left little doubt that traumatic memories function differently from other memories. […]

The people listening to the sad memories, which often involved the death of a family member, showed consistently high engagement of the hippocampus, part of the brain that organizes and contextualizes memories. When the same people listened to their traumatic memories — of sexual assaults, fires, school shootings and terrorist attacks — the hippocampus was not involved. […]

“traumatic memories are not experienced as memories as such,” but as “fragments of prior events, subjugating the present moment.” The traumatic memories appeared to engage a different area of the brain — the posterior cingulate cortex, or P.C.C., which is usually involved in internally directed thought, like introspection or daydreaming. The more severe the person’s PTSD symptoms were, the more activity appeared in the P.C.C. What is striking about this finding is that the P.C.C. is not known as a memory region, but one that is engaged with “processing of internal experience”

{ NYT | Continue reading }

quote { Emmanuel Levinas, Time and the other (page 69), 1979 | PDF }

no known drug, including caffeine, can effectively reverse sleep deprivation.

The reason has to do, in part, with the circadian rhythm of a chemical called adenosine that plays a major role in the regulation of sleep.

When you awake from a restful night of sleep, the adenosine level in your brain is at its nadir. Throughout the day, it steadily rises and gradually produces the pressure to sleep in the evening. During sleep, adenosine is cleared from the brain, which helps us wake up and stay alert.

Caffeine is a powerful antagonist at adenosine receptors in the brain, blocking the sedating effects of adenosine and making you feel stimulated and mentally sharp.

Here’s the problem. If you cut short your normal night of sleep, adenosine is not fully cleared from the brain. With chronic sleep deprivation, adenosine levels continue to rise, creating a persistent sense of fatigue and sleepiness and impairing cognitive function.

The brain adapts to this flood of adenosine by increasing the number of adenosine receptors in an attempt to get you to fall asleep, which of course only makes you feel more tired.

You will probably respond by increasing your caffeine consumption, in an attempt to block rising adenosine activity, which can only be restored by a normal night of sleep — the very thing my patient was trying to cut short.

Sleep deprivation doesn’t just make you tired. It impairs the brain’s ability to consolidate memory.

During sleep, your neurons are remodeled and change their firing pattern, which helps burn in the memories that are formed during the day.

Too little sleep can also exacerbate preexisting depression and anxiety disorders and make people with no previous mental health problems generally more angry and impulsive. […]

Intriguingly, while caffeine can’t eradicate sleep deprivation, it does appear to offset some of the harmful cognitive effects of sleep loss on memory. […]

Caffeine is usually metabolized within four to six hours. […] Some people are genetically slow metabolizers of caffeine and will have significant sleep-onset insomnia even from early morning coffee.

And here’s the most effective trick for falling asleep, which has been studied and shown to be as effective — if not more — than any hypnotic drug. Don’t do anything in bed except sleep or have sex — no reading, listening to music or anything else.

{ Washington Post | Continue reading }

When he was two years old, Ben stopped seeing out of his left eye. His mother took him to the doctor and soon discovered he had retinal cancer in both eyes. After chemotherapy and radiation failed, surgeons removed both his eyes. For Ben, vision was gone forever.

But by the time he was seven years old, he had devised a technique for decoding the world around him: he clicked with his mouth and listened for the returning echoes. This method enabled Ben to determine the locations of open doorways, people, parked cars, garbage cans, and so on. He was echolocating: bouncing his sound waves off objects in the environment and catching the reflections to build a mental model of his surroundings.

Echolocation may sound like an improbable feat for a human, but thousands of blind people have perfected this skill, just like Ben did. The phenomenon has been written about since at least the 1940s, when the word “echolocation” was first coined in a Science article titled “Echolocation by Blind Men, Bats, and Radar.” […]

Neuroscience used to think that different parts of the brain were predetermined to perform specific functions. But more recent discoveries have upended the old paradigm. One part of the brain may initially be assigned a specific task; for instance, the back of our brain is called the “visual cortex” because it usually handles sight. But that territory can be reassigned to a different task. There is nothing special about neurons in the visual cortex: they are simply neurons that happen to be involved in processing shapes or colors in people who have functioning eyes. But in the sightless, these same neurons can rewire themselves to process other types of information. […]

we refer to the brain’s plasticity as “livewiring” to spotlight how this vast system of 86 billion neurons and 0.2 quadrillion connections rewires itself every moment of your life. […]

In Ben’s case, his brain’s flexible wiring repurposed his visual cortex for processing sound. As a result, Ben had more neurons available to deal with auditory information, and this increased processing power allowed Ben to interpret soundwaves in shocking detail. Ben’s super-hearing demonstrates a more general rule: the more brain territory a particular sense has, the better it performs. […]

Recent decades have yielded several revelations about livewiring, but perhaps the biggest surprise is its rapidity. Brain circuits reorganize not only in the newly blind, but also in the sighted who have temporary blindness. In one study, sighted participants intensively learned how to read Braille. Half the participants were blindfolded throughout the experience. At the end of the five days, the participants who wore blindfolds could distinguish subtle differences between Braille characters much better than the participants who didn’t wear blindfolds. Even more remarkably, the blindfolded participants showed activation in visual brain regions in response to touch and sound. When activity in the visual cortex was temporarily disrupted, the Braille-reading advantage of the blindfolded participants went away. In other words, the blindfolded participants performed better on the touch- related task because their visual cortex had been recruited to help. After the blindfold was removed, the visual cortex returned to normal within a day, no longer responding to touch and sound.

But such changes don’t have to take five days; that just happened to be when the measurement took place. When blindfolded participants are continuously measured, touch-related activity shows up in the visual cortex in about an hour. […]

In the ceaseless competition for brain territory, the visual system has a unique problem: due to the planet’s rotation, all animals are cast into darkness for an average of 12 out of every 24 hours. (Of course, this refers to the vast majority of evolutionary time, not to our present electrified world.) Our ancestors effectively were unwitting participants in the blindfold experiment, every night of their entire lives.

So how did the visual cortex of our ancestors’ brains defend its territory, in the absence of input from the eyes?

We suggest that the brain preserves the territory of the visual cortex by keeping it active at night. In our “defensive activation theory,” dream sleep exists to keep neurons in the visual cortex active, thereby combating a takeover by the neighboring senses. […]

In humans, sleep is punctuated by rapid eye movement (REM) sleep every 90 minutes. This is when most dreaming occurs. (Although some forms of dreaming can occur during non-REM sleep, such dreams are abstract and lack the visual vividness of REM dreams.)

REM sleep is triggered by a specialized set of neurons that pump activity straight into the brain’s visual cortex, causing us to experience vision even though our eyes are closed.

{ Time | Continue reading }

image { Michael Mann, Manhunter, 1986 }

quote { Does the popular quote, “No artist tolerates reality,” belong to Nietzsche? }

Female 29 years of age, university student, from dysfunctional family. She began her suffering 11 years ago with personality dissociation, characterized by aversion to sacred objects and images, and psychomotor agitation with transient states of loss of consciousness with manifestations of spiritual possession that required psychiatric, and psychological treatment, and 5 exorcisms without improvement over a period of ten years. […]

With informed consent, a fMRI was accomplished before and in the beginning of a possession induced by exorcism performed by a Catholic priest. […] due to the involuntary motor activity and the patient’s loss of consciousness, it is not possible to perform the analysis completely in this case.

{ Trends in Medicine | Continue reading }

There were 16 people in total that participated in the project “Resting Stated-Tractography-fMRI in initial phase of spiritual possession.” 13 of them are health professionals: a surgeon, psychiatrist, psychologist, neurophysiologist, family medicine physician, neurosurgeon, 2 radiology technicians, a gynecologist, medical doctor, diagnostic radiology physician, exorcist and patient (Ex former medical student). The priest, mother and an aunt of the patient were not included. […]

8 out of 13 participants (61.53%) had accidents and sudden events that put their lives in danger […]

Eight days before the exorcism, the psychiatrist experienced malfunctioning of his computer […]

Seven days after the exorcism, the surgeon had a head trauma, chest trauma and multiple bruises in a forest accident with fall from a height of one meter; he also had a MVA (motor vehicle accident) 15 minutes before receiving the images of the patient’s tractografies […]

22 days after the exorcism the medical doctor presented sudden breakup of a ten years relationship with her boyfriend.

Eight days before and during the exorcism, the father of the patient (a family medicine physician) presented chest and back pain with a normal electrocardiogram; 37 days after the exorcism he is admitted to the Critical Care Unit “CCU” for massive acute myocardial infarction, with loss of myocardial function of 90%.

41 days after the exorcism, the gynecologist is involved in an offense she did not commit.

[…]

On the survey carried out, the 12 participants are much more afraid of organized crime in Mexico than of the devil.

{ Trends in Medicine | PDF }

An astrophysicist of the University of Bologna and a neurosurgeon of the University of Verona compared the network of neuronal cells in the human brain with the cosmic network of galaxies, and surprising similarities emerged. […]

The human brain functions thanks to its wide neuronal network that is deemed to contain approximately 69 billion neurons. On the other hand, the observable universe can count upon a cosmic web of at least 100 billion galaxies. Within both systems, only 30% of their masses are composed of galaxies and neurons. Within both systems, galaxies and neurons arrange themselves in long filaments or nodes between the filaments. Finally, within both system, 70% of the distribution of mass or energy is composed of components playing an apparently passive role: water in the brain and dark energy in the observable Universe. […]

Probably, the connectivity within the two networks evolves following similar physical principles, despite the striking and obvious difference between the physical powers regulating galaxies and neurons”

{ Università di Bologna | Continue reading }

oil on canvas { Karel Appel, Portrait, 1966 }

Can lab-grown brains become conscious?

These tiny structures, known as brain organoids, are grown from human stem cells and have become a familiar fixture in many labs that study the properties of the brain. Muotri, a neuroscientist at the University of California, San Diego (UCSD), has found some unusual ways to deploy his. He has connected organoids to walking robots, modified their genomes with Neanderthal genes, launched them into orbit aboard the International Space Station, and used them as models to develop more human-like artificial-intelligence systems. Like many scientists, Muotri has temporarily pivoted to studying COVID-19, using brain organoids to test how drugs perform against the SARS-CoV-2 coronavirus.

But one experiment has drawn more scrutiny than the others. In August 2019, Muotri’s group published a paper in Cell Stem Cell reporting the creation of human brain organoids that produced coordinated waves of activity, resembling those seen in premature babies1. The waves continued for months before the team shut the experiment down. […]

The concerns over lab-grown brains have also highlighted a blind spot: neuroscientists have no agreed way to define and measure consciousness. Without a working definition, ethicists worry that it will be impossible to stop an experiment before it crosses a line.

{ Nature | Continue reading }

Electrical activity from the brains of a pair of human subjects was transmitted to the brain of a third individual in the form of magnetic signals, which conveyed an instruction to perform a task in a particular manner. […]

In [another] report, a human using a noninvasive brain interface linked, via computer, to the BCI of an anesthetized rat was able to move the animal’s tail.

{ Scientific American | Continue reading }

art { Barbara Stauffacher Solomon, San Francisco Museum of Art, Calendar, 1969 }

The mind-body problem enjoyed a major rebranding over the last two decades and is generally known now as the “hard problem” of consciousness […] Fast forward to the present era and we can ask ourselves now: Did the hippies actually solve this problem? My colleague Jonathan Schooler of the University of California, Santa Barbara, and I think they effectively did, with the radical intuition that it’s all about vibrations … man. Over the past decade, we have developed a “resonance theory of consciousness” that suggests that resonance—another word for synchronized vibrations—is at the heart of not only human consciousness but of physical reality more generally. […]

Stephen Strogatz provides various examples from physics, biology, chemistry and neuroscience to illustrate what he calls “sync” (synchrony) […] Fireflies of certain species start flashing their little fires in sync in large gatherings of fireflies, in ways that can be difficult to explain under traditional approaches. […] The moon’s rotation is exactly synced with its orbit around the Earth such that we always see the same face. […]

The panpsychist argues that consciousness (subjectivity) did not emerge; rather, it’s always associated with matter, and vice versa (they are two sides of the same coin), but mind as associated with most of the matter in our universe is generally very simple. An electron or an atom, for example, enjoy just a tiny amount of consciousness. But as matter “complexifies,” so mind complexifies, and vice versa.

{ Scientific American | Continue reading | Thanks Tim }

The new “eyes wide shut” illusion uses a standard enlarging (shaving or makeup) mirror. Close one eye and look at the closed eye in the mirror; the eye should take up most of the mirror. Switch eyes to see the other closed eye. Switch back-and-forth a few times, then open both eyes. You see an open eye. Which eye is it? To find out, close one eye. Whichever you close, that’s the eye you see. How can this be possible? The brain is fusing two images of the two eyes.

{ Perception | Continue reading | Thanks Brad! }

However, no one has hitherto laid down the limits to the powers of the body, that is, no one has as yet been taught by experience what the body can accomplish solely by the laws of nature, in so far as she is regarded as extension. No one hitherto has gained such an accurate knowledge of the bodily mechanism, that he can explain all its functions; nor need I call attention to the fact that many actions are observed in the lower animals, which far transcend human sagacity, and that somnambulists do many things in their sleep, which they would not venture to do when awake: these instances are enough to show, that the body can by the sole laws of its nature do many things which the mind wonders at.

Again, no one knows how or by what means the mind moves the body, nor how many various degrees of motion it can impart to the body, nor how quickly it can move it.

{ Spinoza, Ethics, III, Proposition II, Scholium | Continue reading }

unrelated { eye colour may not be a priority when choosing a partner }

In a study published in Nature Neuroscience on Jan. 21, neuroscientists and systems biologists from Harvard Medical School reveal just how inexorably interwoven nature and nurture are.

Using novel technologies developed at HMS, the team looked at how a single sensory experience affects gene expression in the brain by analyzing more than 114,000 individual cells in the mouse visual cortex before and after exposure to light.

Their findings revealed a dramatic and diverse landscape of gene expression changes across all cell types, involving 611 different genes, many linked to neural connectivity and the brain’s ability to rewire itself to learn and adapt.

The results offer insights into how bursts of neuronal activity that last only milliseconds trigger lasting changes in the brain, and open new fields of exploration for efforts to understand how the brain works.

{ Harvard Medical School | Continue reading }

art { Josef Albers, Hotel Staircase, Geneva, 1929/1932 }

When you’re doing two things at once – like listening to the radio while driving – your brain organizes itself into two, functionally independent networks, almost as if you temporarily have two brains. That’s according to a fascinating new study from University of Wisconsin-Madison neuroscientists Shuntaro Sasai and colleagues.

{ Neuroskeptic | Continue reading }

art { Harri Peccinotti }

When one draws a correlation between body mass and brain mass for living primates and extinct species of Homo, it is not humans—whose brains are three times larger than those of chimpanzees, their closest primate relative—that are an outlier. Instead, it is the great apes—gorillas and the orangutan—with brains far smaller than would be expected in relation to their body mass. We are the new normal in evolution while the great apes are the evolutionary oddity that requires explanation.

But we remain special in another way. Our 86 billion neurons need so much energy that if we shared a way of life with other primates we couldn’t possibly survive: there would be insufficient hours in the day to feed our hungry brain. It needs 500 calories a day to function, which is 25 percent of what our entire body requires.

{ New York Review of Books | Continue reading }

art { Christopher Wool, Untitled, 2006 }

Neil Harbisson, an artist with colorblindness, has a chip implanted in his head and antenna attached to his skull that allows him to hear a different frequency of sound for each color.

Meanwhile, his artistic partner Moon Ribas has an implanted magnet that allows her to feel the tremors of earthquakes around the world.

{ Quartz | Continue reading }

Normal aging is known to be accompanied by loss of brain substance.

Machine learning was used to estimate brain ages in meditators and controls.

At age 50, brains of meditators were estimated to be 7.5 years younger than that of controls.

These findings suggest that meditation may be beneficial for brain preservation.

{ NeuroImage | Continue reading }

image { Jonathan Puckey }

Theory of Mind (ToM) is the ability to understand the perspectives, mental states and beliefs of others in order to anticipate their behaviour and is therefore crucial to social interactions.

Although fMRI has been widely used to establish the neural networks implicated in ToM, little is known about the timing of ToM-related brain activity.

We used magnetoencephalography (MEG) to measure the neural processes underlying ToM, as MEG provides very accurate timing and excellent spatial localization of brain processes. We recorded MEG activity during a false belief task, a reliable measure of ToM, in twenty young adults (10 females). […]

Our findings extend the literature by demonstrating the timing and duration of neural activity in the main regions involved in the “mentalizing” network, showing that activations related to false belief in adults are predominantly right lateralized and onset around 100 ms.

{ NeuroImage | Continue reading }

still { Total Recall, 1990 }

264 right-handed, 246 mixed-handed and 360 left-handed students were requested to indicate on five maps of cinema halls what place they would choose. All three handedness groups showed a preference for the right and a corresponding directional bias towards the left space. However, they differed significantly from each other on the magnitude of this bias which was most pronounced in right and less in left handers. […]

It is hypothesized that right, mixed and left handers differ in a large number of behavioral choices and strategies, modeled by cerebrally lateralized mechanisms and that the cinema seating preference is only one of them.

{ Cortex | Continue reading }

still { Jean-Luc Godard, Nouvelle vague, 1990 }

The benefits of mindfulness meditation, increasingly popular in recent years, are supposed to be many: reduced stress and risk for various diseases, improved well-being, a rewired brain. But the experimental bases to support these claims have been few. Supporters of the practice have relied on very small samples of unrepresentative subjects, like isolated Buddhist monks who spend hours meditating every day, or on studies that generally were not randomized and did not include placebo­control groups.

This month, however, a study published in Biological Psychiatry brings scientific thoroughness to mindfulness meditation and for the first time shows that, unlike a placebo, it can change the brains of ordinary people and potentially improve their health. […]

First they recruited 35 unemployed men and women who were seeking work and experiencing considerable stress. Blood was drawn and brain scans were given. Half the subjects were then taught formal mindfulness meditation at a residential retreat center; the rest completed a kind of sham mindfulness meditation that was focused on relaxation and distracting oneself from worries and stress. […]

At the end of three days, the participants all told the researchers that they felt refreshed and better able to withstand the stress of unemployment. Yet follow-up brain scans showed differences in only those who underwent mindfulness meditation. There was more activity, or communication, among the portions of their brains that process stress-related reactions and other areas related to focus and calm. Four months later, those who had practiced mindfulness showed much lower levels in their blood of a marker of unhealthy inflammation than the relaxation group, even though few were still meditating.

{ NY Times | Continue reading }

Marijuana is one of the most commonly used drugs in the United States, and use during adolescence — when the brain is still developing — has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects.

The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants’ family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9–12 y, before marijuana involvement, and again at ages 17–20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period.

Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings.

Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.

{ Proceedings of the National Academy of Sciences }

photo { Julia Margaret Cameron, Paul and Virginia, 1864 }

Starting at age 55, our hippocampus, a brain region critical to memory, shrinks 1 to 2 percent every year, to say nothing of the fact that one in nine people age 65 and older has Alzheimer’s disease. The number afflicted is expected to grow rapidly as the baby boom generation ages. Given these grim statistics, it’s no wonder that Americans are a captive market for anything, from supposed smart drugs and supplements to brain training, that promises to boost normal mental functioning or to stem its all-too-common decline. […]

A few years back, a joint study by BBC and Cambridge University neuroscientists put brain training to the test. Their question was this: Do brain gymnastics actually make you smarter, or do they just make you better at doing a specific task? […] All subjects took a benchmark cognitive test, a kind of modified I.Q. test, at the beginning and at the end of the study. Although improvements were observed in every cognitive task that was practiced, there was no evidence that brain training made people smarter.

There was, however a glimmer of hope for subjects age 60 and above. Unlike the younger participants, older subjects showed a significant improvement in verbal reasoning, one of the components of the benchmark test, after just six weeks of brain training, so the older subjects continued in a follow-up study for a full 12 months.

Results of this follow-up study, soon to be published in a peer-reviewed journal, generally show that continued brain training helps older subjects maintain the improvement in verbal reasoning seen in the earlier study. This is good news because it suggests that brain exercise might delay some of the effects of aging on the brain.

{ NY Times | Continue reading }

In a stunning discovery that overturns decades of textbook teaching, researchers at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by vessels previously thought not to exist. That such vessels could have escaped detection when the lymphatic system has been so thoroughly mapped throughout the body is surprising on its own, but the true significance of the discovery lies in the effects it could have on the study and treatment of neurological diseases ranging from autism to Alzheimer’s disease to multiple sclerosis.

{ EurekAlert | Continue reading }

unrelated { The benefits of a herpes infection }