researchers have almost always taken participants’ identified age at the time of their first memory at face value. But these age estimates seem to be vulnerable to consistent errors.

As a consequence, the long-standing belief of when earliest memories begin may be wrong, and memories may be much earlier than prior research suggests. […]

Thus, if someone thinks that they remember an event that occurred when they were 3 or 4 years of age, they were probably much younger. In other words, many people can remember back to when they were 2 years of age or even younger, but do not realize it because of systematic errors in memory dating and because they only tried to recall a single memory.

{ Journal of Applied Research in Memory and Cognition | Continue reading }

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 }

A cornerstone of cognitive science is that mental systems are limited: There is a maximum amount of information they can process or store, beyond which performance breaks down. Yet so far the study of such limits has been focused on core systems like attention and memory. Here we explore the limit of self-representation, the ability to represent someone or something as you. […]

results are consistent with the view that the mind employs a cognitive architecture that can represent at most one self at a time, and which serially switches out the items it represents. […]

The self-representational limit of one item at a time differs markedly from known limits on other systems, like attention and short-term memory. The number of items we can both track and remember in short-term memory is greater than one, and somewhat flexible depending on the nature of the stimuli and their relations. For instance, people can track more items if they are evenly spaced out on the display rather than clumped together (Alvarez & Franconeri, 2007), remember more items if they are less complex (e.g., simple colors rather than shaded cubes) (Alvarez & Cavanagh, 2004), and both track and remember more items if they span the visual hemifields rather than occur within a single visual hemifield (Alvarez & Cavanagh, 2005; Strong & Alvarez, 2020). Self-representation appears to have a limit that is more severe and inflexible.

{ PsyArXiv | Continue reading }

Humans can think about possible states of the world without believing in them, an important capacity for high-level cognition.

Here we use fMRI and a novel “shell game” task to test two competing theories about the nature of belief and its neural basis.

According to the Cartesian theory, information is first understood, then assessed for veracity, and ultimately encoded as either believed or not believed. According to the Spinozan theory, comprehension entails belief by default, such that understanding without believing requires an additional process of “unbelieving”. […]

findings are consistent with a version of the Spinozan theory whereby unbelieving is an inhibitory control process.

{ PsyArXiv | 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? }

Books are horrible at teaching. So are lectures. So are documentaries. If to teach means to impart lasting knowledge, then our current educational media are lousy teachers. We encounter thousands of concepts a year, yet the vast majority fades from our memory into the ether, never to be held again. We forget. […]

We also forget information at an exponentially decaying rate; more than half of what we process is gone within the first 20 minutes. This means that we need several prompts to make persistent memories. (For more on memory failure modes, see Schachter’s Seven Sins of Memory.). […]

What are some dimensions to consider if we want machines to augment our ability to remember?

{ Machines + Society | Continue reading }

I’m 62 years old as I write this. Like many of my friends, I forget names that I used to be able to conjure up effortlessly. When packing my suitcase for a trip, I walk to the hall closet and by the time I get there, I don’t remember what I came for.

And yet my long-term memories are fully intact. I remember the names of my third-grade classmates, the first record album I bought, my wedding day.

This is widely understood to be a classic problem of aging. But as a neuroscientist, I know that the problem is not necessarily age-related.

Short-term memory contains the contents of your thoughts right now, including what you intend to do in the next few seconds. It’s doing some mental arithmetic, thinking about what you’ll say next in a conversation or walking to the hall closet with the intention of getting a pair of gloves.

Short-term memory is easily disturbed or disrupted. It depends on your actively paying attention to the items that are in the “next thing to do” file in your mind. You do this by thinking about them, perhaps repeating them over and over again (“I’m going to the closet to get gloves”). But any distraction — a new thought, someone asking you a question, the telephone ringing — can disrupt short-term memory. Our ability to automatically restore the contents of the short-term memory declines slightly with every decade after 30. […]

Some aspects of memory actually get better as we age. For instance, our ability to extract patterns, regularities and to make accurate predictions improves over time because we’ve had more experience. (This is why computers need to be shown tens of thousands of pictures of traffic lights or cats in order to be able to recognize them). If you’re going to get an X-ray, you want a 70-year-old radiologist reading it, not a 30-year-old one. […]

Older adults have to search through more memories than do younger adults to find the fact or piece of information they’re looking for. Your brain becomes crowded with memories and information. It’s not that you can’t remember — you can — it’s just that there is so much more information to sort through. 

{ NY Times | Continue reading }

Targeted Memory Reactivation During Sleep Improves Next-Day Problem Solving

Many people have claimed that sleep has helped them solve a difficult problem, but empirical support for this assertion remains tentative. […]

In the evening, we presented 57 participants with puzzles, each arbitrarily associated with a different sound. While participants slept overnight, half of the sounds associated with the puzzles they had not solved were surreptitiously presented.

The next morning, participants solved 31.7% of cued puzzles, compared with 20.5% of uncued puzzles (a 55% improvement). […]

These results demonstrate that cuing puzzle information during sleep can facilitate solving, thus supporting sleep’s role in problem incubation.

{ Sage | Continue reading }

art { John Gerrard, Western Flag (Spindletop Texas), 2017 }

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 }

During my clinical internship over 20 years ago, my boss, a psychiatrist, asked me to research how PMS prevents women from thinking clearly. I told him he was a relic of the Stone Age. Women were as consistently clearheaded as men, if not more so.

But recently, a researcher in my lab, Joe Andreano, an expert on female hormones, showed me some surprising data. As a woman’s levels of progesterone and estrogen vary, so does the connectivity between two brain networks: the default mode network and the salience network. These networks play key roles in creating your emotional life.

If I hadn’t seen the data with my own eyes, I wouldn’t have believed it.

When scientists say that brain networks are “strongly connected” or have “increased connectivity,” it means that the neurons have an easier time passing information back and forth. In the case of the default mode and salience networks, increased connectivity means (among other things) that you may experience more powerful negative emotions. In earlier research, for example, my colleagues and I found that people reported more intense sadness when watching the sentimental movie “Stepmom” and more intense fear when watching the horror movie “The Ring Two” in the moments when these brain networks were more connected.

There has also been a flurry of recent studies indicating that certain cocktails of ovarian hormones can make women feel lousy, particularly a week or so before menstruation. Female test subjects who receive ovarian hormones designed to mimic the menstrual cycle, for example, report an increase in negative mood. They also remember negative material better, and they show enhanced stress responses. […]

 I’m not saying that women turn into helpless snowflakes for a few days each month. I’m just saying that the biology is real: Some women may have a short window before their period when, if something bad happens, they will feel more negative or stressed and will remember that unpleasant event more easily.

A few bad feelings or memories aren’t inherently harmful, of course. But this window of vulnerability, combined with other risk factors, could increase the odds of developing mood disorders like depression.

{ NY Times | Continue reading }

enamel on linen { Christopher Wool, Untitled, 1998 }

Physical pain represents a common feature of Bondage and Discipline/Dominance and Submission/Sadism and Machochism (BDSM) activity. This article explores the literature accounting for how painful stimuli may be experienced as pleasurable among practitioners of BDSM, and contrasting this with how it is experienced as painful among non-BDSM individuals. […] The experience of pain in this context can bring about altered states of consciousness that may be similar to what occurs during mindfulness meditation.

{ The Journal of Sex Research | Continue reading }

Faces are a primary source of social information, but little is known about the sequence of neural processing of personally relevant faces, such as those of our loved ones.

We applied representational similarity analyses to EEG-fMRI measurement of neural responses to faces of personal relevance to participants – their romantic partner and a friend – compared to a stranger. Faces expressed fear, happiness or no emotion. […]

Models of face processing postulate that recognition of face identity takes place with structural encoding in the fusiform gyrus around 170 ms after stimulus onset. We provide evidence that the high personal relevance of our friends’ and loved ones’ faces is detected prior to structural encoding […] as early as 100 ms after stimulus onset. […] Our findings imply that our brain can ‘bypass’ full structural encoding of face identity in order to prioritise the processing of faces most relevant to us.

{ BioRxiv | Continue reading }

acrylic on canvas { Nychos, Barbie Meltdown, 2016 }

In a series of experiments, students listened to stories and then took a test of how much information they remembered an hour later. Their recall spiked by 10 to 30 percent if they had been randomly assigned to sit and do nothing in a dark, quiet room for a few minutes right after hearing the story. Your mind needs rest and space to consolidate and store information. […]

Don’t bother with rereading or highlighting. Research reveals that they don’t help much. […]

The best way to learn something truly is to teach it.

{ NY Times | Continue reading }

Study provides insight into the neurobiology of dying. Investigators performed continuous patient monitoring following Do Not Resuscitate - Comfort Care orders in patients with devastating brain injury to investigate the mechanisms and timing of events in the brain and the circulation during the dying process.

{ ScienceDaily | Continue reading }

Oxygen deprivation results in brain injury. For years, researchers have been studying the underlying processes in animals: within 20 to 40 seconds, the brain enters an ‘energy-saving mode’ - it becomes electrically inactive, and all interneuronal communication ceases. Within a few minutes, the brain’s fuel reserves have become depleted that maintain the uneven distribution of ions between the inside and outside of nerve cells, and the ion gradients start to break down. This breakdown takes the form of a massive wave of electrochemical energy release in the form of heat, which is known as ’spreading depolarization’. More vividly described as a ‘brain tsunami’, this energy loss spreads through the cortex and other areas of the brain, triggering pathophysiological cascades which gradually poison the nerve cells. Importantly, this wave remains reversible up to a certain point in time: nerve cells will recover fully if circulation is restored before this point is reached. However, if circulation remains disrupted, the cells will die. Until now, recordings of electrical brain activity obtained from human subjects have been of limited applicability, and experts have been divided as to the transferability of results from animal-based research. […]

“We were able to show that terminal spreading depolarization is similar in humans and animals. Unfortunately, the research community has been ignoring this essential process of central nervous system injury for decades, all because of the mistaken assumption that it does not occur in humans,” explains Prof. Dreier.

{ EurekAlert | Continue reading }

paint on plaster { Eduardo Paolozzi, Targets, 1948 }

Try this experiment: Pick a famous movie—Casablanca, say—and summarize the plot in one sentence. Is that plot you just described the thing you remember most about it? Doubtful. Narrative is a necessary cement, but it disappears from memory.

{ Peter Greenaway | Continue reading }

“I almost always remember where I was and I remember the book itself. I remember the physical object,” says Paul, the editor of The New York Times Book Review, who reads, it is fair to say, a lot of books. “I remember the edition; I remember the cover; I usually remember where I bought it, or who gave it to me. What I don’t remember—and it’s terrible—is everything else.” […] “Memory generally has a very intrinsic limitation,” says Faria Sana, an assistant professor of psychology at Athabasca University, in Canada. “It’s essentially a bottleneck.” The “forgetting curve,” as it’s called, is steepest during the first 24 hours after you learn something. Exactly how much you forget, percentage-wise, varies, but unless you review the material, much of it slips down the drain after the first day, with more to follow in the days after, leaving you with a fraction of what you took in.

{ The Atlantic | Continue reading }

Human memory systems are subject to many imperfections, including memory distortions and the creation of false memories. Here, we demonstrate a case where memory distortion is adaptive, increasing the overall accuracy of memories. […]

Although participants’ memories were systematically distorted, they were distorted in a way that is consistent with minimizing their average error […]

Thus, memory distortion may not always be maladaptive: in some cases, distortion can result from a memory system that optimally combines information in the service of the broader goals of the person. Furthermore, this framework for thinking about memory distortion suggests that false memory can be thought of on a continuum with true memory: the greater uncertainty participants have about an individual item memory, the more they weight their gist memory [Gist traces are fuzzy representations of a past event]; with no item information, they weight only their gist memory.

{ PsyArXiv | Continue reading }

photo { Ana Mendieta, Untitled, from Silueta Series, Iowa, 1978 }

Two theoretical frameworks have been proposed to account for the representation of truth and falsity in human memory: the Cartesian model and the Spinozan model. Both models presume that during information processing a mental representation of the information is stored along with a tag indicating its truth value. However, the two models disagree on the nature of these tags. According to the Cartesian model, true information receives a “true” tag and false information receives a “false” tag. In contrast, the Spinozan model claims that only false information receives a “false” tag, whereas untagged information is automatically accepted as true. […]

The results of both experiments clearly contradict the Spinozan model but can be explained in terms of the Cartesian model.

{ Memory & Cognition | PDF }

art { Richard Long, Dusty Boots Line, The Sahara, 1988 }

The image of the world that we see is continuously deformed and fragmented by foreshortenings, partial overlapping, and so on, and must be constantly reassembled and interpreted; otherwise, it could change so much that we would hardly recognize it. Since pleasure has been found to be involved in visual and cognitive information processing, the possibility is considered that anhedonia (the reduction of the ability to feel pleasure) might interfere with the correct reconstruction and interpretation of the image of the environment and alter its appearance.

{ Schizophrenia Research and Treatment | Continue reading }

Grapheme-color synesthesia is a neurological phenomenon in which viewing a grapheme elicits an additional, automatic, and consistent sensation of color.

Color-to-letter associations in synesthesia are interesting in their own right, but also offer an opportunity to examine relationships between visual, acoustic, and semantic aspects of language. […]

Numerous studies have reported that for English-speaking synesthetes, “A” tends to be colored red more often than predicted by chance, and several explanatory factors have been proposed that could explain this association.

Using a five-language dataset (native English, Dutch, Spanish, Japanese, and Korean speakers), we compare the predictions made by each explanatory factor, and show that only an ordinal explanation makes consistent predictions across all five languages, suggesting that the English “A” is red because the first grapheme of a synesthete’s alphabet or syllabary tends to be associated with red.

We propose that the relationship between the first grapheme and the color red is an association between an unusually-distinct ordinal position (”first”) and an unusually-distinct color (red).

{ Cortex | Continue reading }

A Black, E white, I red, U green, O blue: vowels,
Someday I shall tell of your mysterious births

{ Arthur Rimbaud | Continue reading }

art { Roland Cat, The pupils of their eyes, 1985 }

Normal consciousness relies, at least in part, on the brain’s Default Mode Network (DMN), according to neuroscientist Robin Carhart-Harris, head of psychedelic research in the brain sciences division of the Imperial College of London medical school. The DMN is a network of interacting brain regions that acts as a cognitive transit hub, integrating and assimilating information. As the name implies, it’s the usual system of organization for your mind. Carhart-Harris says the DMN “gives coherence to cognition” by connecting different regions of the brain, and is considered the “orchestrator of the self.”

Carhart-Harris and his colleagues found what seems to be an important function of the DMN inadvertently. While studying brain networks, they got curious about what changes might occur when people are under the effects of hallucinogens. In studies analyzing the effects of psilocybin on brain wave oscillation and blood flow, they found that when the DMN was inactive, an alternate network of consciousness seemed to arise.

When some study subjects tested psilocybin, they reported a strong sense of interconnectedness, as well as spiritual, magical, and supernatural feelings.

In the alternate mode, brains produced a different world that offered other sensations and realizations than in everyday life. In this mode, the self wasn’t the protagonist of the narrative. Meanwhile, scans of blood flow and brain wave oscillations showed new, unusual—but orderly and synchronous—connections forming between cortical regions, as if the brain was reorganizing its network. This led Carhart-Harris to posit that the DMN generates the feeling we each have that we’re individuals, a feeling that manifests very strongly as reality. And that means we can temporarily switch off, or mute, this part of the brain.

{ Quartz | Continue reading }

According to the famous work of Roger Sperry and Michael Gazzaniga, “split brain” patients seem to experience a split in consciousness: the left and the right side of their brain can independently become aware of, and respond, to stimuli. Split brain patients are those who underwent surgery to sever the corpus callosum, the nerve tract connecting the two hemispheres of the brain.

{ Neuroskeptic | Continue reading }

art { Leah Schrager }