Posts Tagged ‘neurology’
“Even though our lives wander, our memories remain in one place”*…
Your correspondent’s fascination with the “memory palace,” the age-old technique of memorization, has shown up in (R)D many times before (e.g., here, here, here, here, here, and here :) That it works has been long understood– but how it works, not so much. Ingrid Wickelgren reports on research that may offer a clue…
After shuffling the cards in a standard 52-card deck, Alex Mullen, a three-time world memory champion, can memorize their order in under 20 seconds. As he flips though the cards, he takes a mental walk through a house. At each point in his journey — the mailbox, front door, staircase and so on — he attaches a card. To recall the cards, he relives the trip.
This technique, called “method of loci” or “memory palace,” is effective because it mirrors the way the brain naturally constructs narrative memories: Mullen’s memory for the card order is built on the scaffold of a familiar journey. We all do something similar every day, as we use familiar sequences of events, such as the repeated steps that unfold during a meal at a restaurant or a trip through the airport, as a home for specific details — an exceptional appetizer or an object flagged at security. The general narrative makes the noteworthy features easier to recall later.
“You are taking these details and connecting them to this prior knowledge,” said Christopher Baldassano, a cognitive neuroscientist at Columbia University. “We think this is how you create your autobiographical memories.”
Psychologists empirically introduced this theory some 50 years ago, but proof of such scaffolds in the brain was missing. Then, in 2018, Baldassano found it: neural fingerprints of narrative experience, derived from brain scans, that replay sequentially during standard life events. He believes that the brain builds a rich library of scripts for expected scenarios — restaurant or airport, business deal or marriage proposal — over a person’s lifetime.
These standardized scripts, and departures from them, influence how and how well we remember specific instances of these event types, his lab has found. And recently, in a paper published in Current Biology in fall 2024, they showed that individuals can select a dominant script for a complex, real-world event — for example, while watching a marriage proposal in a restaurant, we might opt, subconsciously, for either a proposal or a restaurant script — which determines what details we remember…
The fascinating details of how, by screening films in a brain scanner, neuroscientists discovered a rich library of neural scripts — from a trip through an airport to a marriage proposal — that form scaffolds for memories of our experiences: “How ‘Event Scripts’ Structure Our Personal Memories,” from @iwickelgren in @quantamagazine.bsky.social.
* Marcel Proust
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As we remember (and lest we forget), we might recall that it was on this date in 1920 that Adolf Hitler, the propaganda head of the German Worker’s Party (DAP) gave a speech (now known as “Hitler’s Hofbräuhaus speech”) to 2,000 followers at a Munich beer hall announcing the change in the party’s name to the Nationalsozialistische Deutsche Arbeiterpartei (“National Socialist German Workers’ Party”, or Nazi Party). It was then that the party officially announced that only persons of “pure Aryan descent” could become members and that their spouses had to be “racially pure” as well.
Oh, and on this date in 1868, an American President (Andrew Johnson) was impeached for the first time.
“I regard consciousness as fundamental. I regard matter as derivative from consciousness. We cannot get behind consciousness. Everything that we talk about, everything that we regard as existing, postulates consciousness.”*…
The image above is from an engaging essay on “Why we need to figure out a theory of consciousness.” But, as Robert Lawrence Kuhn argues, in practice the issue with “the Hard Problem” might better be understood as the need to choose among, then build upon (one or a few of) the myriad theories that we have. Helpfully, Kuhn has surveyed and mapped that theoretical landscape…
Explanations of consciousness abound and the radical diversity of theories is telling. Explanations, or theories, are said to work at astonishingly divergent orders of magnitude and putative realms of reality. My purpose here must be humble: collect and categorize, not assess and adjudicate. Seek insights, not answers.
Unrealistically, I’d like to get them all, at least all contemporary theories that are sufficiently distinct with explanations that can surmount an arbitrary hurdle of rationality or conceivability. Falsification or verification is not on the agenda. I’m less concerned about the ontological truth of explanations/theories than in identifying them and then locating them on a “Landscape” to enable categorization and assess relationships. Next, I assess implications of categories for “big questions.” Thus, this Landscape is not about how consciousness is measured or evolved or even works, but about what consciousness is and what difference it makes.
It’s the classic “mind-body problem:” How do the felt experiences in our minds relate to the neural processes in our brains? How do mental states, whether sensory, cognitive, emotional, or even noumenal (selfless) awareness, correlate with brain states? The Landscape of Consciousness explanations or theories I want to draw is as broad as possible, including those that cannot be subsumed by, and possibly not even accessed by, the scientific method. This freedom from constraint, as it were, is no excuse for wooly thinking. Standards of rationality and clarity of argument must be maintained even more tenaciously, and bases of beliefs must be specified even more clearly.
I have two main aims: (i) gather and describe the various theories and array them in some kind of meaningful structure of high-level or first-order categories (and under Materialism, subcategories); and (ii) assess their implications, with respect to four big questions: meaning/purpose/value (if any); artificial intelligence (AI) consciousness; virtual immortality; and survival beyond death.
Theories overlap; some work together. Moreover, while a real-world landscape of consciousness, even simplified, would be drawn with three dimensions (at least), with multiple kinds and levels of nestings—a combinatorial explosion (and likely no closer to truth)—I satisfice with a one-dimensional toy-model. I array all the theories on a linear spectrum, simplistically and roughly, from the “most physical” on the left (at the beginning) to the “least physical” on the right (near the end). (I have two final categories after this spectrum.) The physicalism assumed in Materialism Theories of consciousness is characterized by naturalistic, science-based perspectives, while non-materialism theories have various degrees of nonphysicalist perspectives outside the ambit of current science and in some cases not subject to the scientific method of experimentation and replicability.
Please do not ascribe the relative importance of a theory to the relative size of its description. The shortest can be the strongest. It sometimes takes more words to describe lesser-known theories. For each description I feel the tension between conciseness and completeness. Moreover, several are not complete theories in themselves but ways to think about consciousness that strike me as original and perhaps insightful…
There follows are survey of the strands of thought/theory depicted here:
Absolutely fascinating: “A landscape of consciousness: Toward a taxonomy of explanations and implications,” from @RobertLawrKuhn via @RogersBacon1…
… Who also published this apposite article: “A Paradigm for AI Consciousness.”
* Max Planck
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As we examine explanations, we might send communicative birthday greetings to Camillo Golgi; he was born on this date in 1843. A biologist and pathologist, he discovered a staining technique called black reaction (sometimes called Golgi’s method or Golgi’s staining in his honor) in 1873, a major breakthrough in neuroscience. He was the first to identify axons and dendrites and their functions. He also identified the sense receptors of muscular sensations. Several structures and phenomena in anatomy and physiology are named for him, including the Golgi apparatus, the Golgi tendon organ and the Golgi tendon reflex.
Golgi’s investigations into the fine structure of the nervous system earned him (with the Spanish histologist Santiago Ramón y Cajal) the 1906 Nobel Prize for Physiology or Medicine.
“Right now I’m having amnesia and déjà vu at the same time. I think I’ve forgotten this before.”*…
Our first three years are usually a blur, and we don’t remember much before age seven. Kristin Ohlson wondered why…
… Freud argued that we repress our earliest memories because of sexual trauma but, until the 1980s, most researchers assumed that we retained no memories of early childhood because we created no memories – that events took place and passed without leaving a lasting imprint on our baby brains. Then in 1987, a study by the Emory University psychologist Robyn Fivush and her colleagues dispelled that misconception for good, showing that children who were just 2.5 years old could describe events from as far as six months into their past.
But what happens to those memories? Most of us assume that we can’t recall them as adults because they’re just too far back in our past to tug into the present, but this is not the case. We lose them when we’re still children…
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To form long-term memories, an array of biological and psychological stars must align, and most children lack the machinery for this alignment. The raw material of memory – the sights, sounds, smells, tastes and tactile sensations of our life experiences – arrive and register across the cerebral cortex, the seat of cognition. For these to become memory, they must undergo bundling in the hippocampus, a brain structure named for its supposed resemblance to a sea horse, located under the cerebral cortex. The hippocampus not only bundles multiple input from our senses together into a single new memory, it also links these sights, sounds, smells, tastes, and tactile sensations to similar ones already stored in the brain. But some parts of the hippocampus aren’t fully developed until we’re adolescents, making it hard for a child’s brain to complete this process.
‘So much has to happen biologically to store a memory,’ the psychologist Patricia Bauer of Emory University told me. There’s ‘a race to get it stabilised and consolidated before you forget it. It’s like making Jell-O: you mix the stuff up, you put it in a mould, and you put it in the refrigerator to set, but your mould has a tiny hole in it. You just hope your Jell-O – your memory – gets set before it leaks out through that tiny hole.’
In addition, young children have a tenuous grip on chronology. They are years from mastering clocks and calendars, and thus have a hard time nailing an event to a specific time and place. They also don’t have the vocabulary to describe an event, and without that vocabulary, they can’t create the kind of causal narrative that [that’s] at the root of a solid memory. And they don’t have a greatly elaborated sense of self, which would encourage them to hoard and reconsider chunks of experience as part of a growing life-narrative.
Frail as they are, children’s memories are then susceptible to a process called shredding. In our early years, we create a storm of new neurons in a part of the hippocampus called the dentate gyrus and continue to form them throughout the rest of our lives, although not at nearly the same rate. A recent study by the neuroscientists Paul Frankland and Sheena Josselyn of the Hospital for Sick Children in Toronto suggests that this process, called neurogenesis, can actually create forgetting by disrupting the circuits for existing memories.
Our memories can become distorted by other people’s memories of the same event or by new information, especially when that new information is so similar to information already in storage. For instance, you meet someone and remember their name, but later meet a second person with a similar name and become confused about the name of the first person. We can also lose our memories when the synapses that connect neurons decay from disuse. ‘If you never use that memory, those synapses can be recruited for something different,’ Bauer told me.
Memories are less vulnerable to shredding and disruptions as the child grows up. Most of the solid memories that we carry into the rest of our lives are formed during what’s called ‘the reminiscence bump’, from ages 15 to 30, when we invest a lot of energy in examining everything to try to figure out who we are. The events, culture and people of that time remain with us and can even overshadow the features of our ageing present, according to Bauer. The movies were the best back then, and so was the music, and the fashion, and the political leaders, and the friendships, and the romances. And so on…
Why we remember so little from our youngest years: “The great forgetting,” from @kristinohlson in @aeonmag.
* Steven Wright
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As we stroll down memory lane, we might spare a thought for Benjamin McLane Spock; he died on this date in 1998. The first pediatrician to study psychoanalysis to try to understand children’s needs and family dynamics, he collected his findings in a 1946 book, The Common Sense Book of Baby and Child Care, which was criticized in some academic circles as being too reliant on anecdotal evidence, and in some conservative circles for promoting (what Norman Vincent Peale and others called) “permissiveness” by parents. Despite that push-back, it became one of the best-selling volumes in history, having sold at the time of Spock’s death in 1998 over 50 million copies in 40 languages.
That’s sick…
…no, I mean actually ill– pathological…
From Chaucer through Shakespeare to Pynchon, puns have amused, even illuminated. But, as readers will know, too much of a good thing is, well… not so good.
Lest we chastise those who offend, Dan Lewis, of Now I Know fame, reminds us that over-punning is in fact a recognized pathology:
… there are some out there who cannot control themselves. Discussions of livestock result in udder failure. Conversations about geometry always end up going on some sort of tangent. Trips to the bakery are a piece of cake — but camping trips are in tents. These people insist that North Korea is evil (it doesn’t have a Seoul), wonder why Ireland is so small (as its capital is always Dublin), and if you’re Russian, argue that you best not be Stalin.
For these people, puns aren’t just a character trait — they’re a neurological disease called Witzelsucht.
Witzelsucht, as summarized by a team of Taiwanese researchers in a paper (pdf here) published in 2005, is marked by “a tendency to tell inappropriate and poor jokes.” Wikipedia, citing another study, notes that a Witzelsucht patient has an “uncontrollable tendency to pun,” finding the jokes “intensely amusing.” These tendencies are caused by an injury to the person’s brain, specifically in his or her right frontal lobe, often caused by stroke. One neurologist, who told MSNBC that he sees several Witzelsucht-afflicted patients each year, described a particularly “dramatic” case: “[He] appeared to be attracted to my reflex hammer. After I checked his deep tendon reflexes and put my hammer down, he picked up the hammer and started to check my reflexes, while giggling.” The humor, of course, was lost on the doctor — and would be to any outside observer as well.
The Taiwanese study speaks of a 56-year-old stroke victim who punned uncontrollably — using a lot of “witticisms and quips,” as the paper describes. The sheer volume of the jokes also interfered with patient’s physicians’ ability to examine him; as the study notes, the man “was euphoric, outspoken, prankish, and was so talkative that an interruption was usually needed to pull the conversation back to the topic or to complete a test.” But like many with the condition, the man was not responsive to the jokes of others.
Unfortunately, there is no cure for Witzelsucht. Io9 notes that some behavioral therapies may be able to blunt the punning, and various medicines may help calm the afflicted down, but in the end, the allure of another pun will certainly prevail.
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As we retreat to more refined raillery, we might recall that it was on this date in 1961 that the first issue of Private Eye was published. A kind of print forerunner of That Was the Week That Was, The Onion, and The Daily Show, the satirical fortnightly remains Britain’s best-selling current affairs magazine.
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