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Michel Roland-Guill

How Our Brains Make Memories / Greg Miller | Science & Nature | Smithsonian Magazine - 0 views

  • Nader, now a neuroscientist at McGill University in Montreal, says his memory of the World Trade Center attack has played a few tricks on him. He recalled seeing television footage on September 11 of the first plane hitting the north tower of the World Trade Center. But he was surprised to learn that such footage aired for the first time the following day. Apparently he wasn’t alone: a 2003 study of 569 college students found that 73 percent shared this misperception.
  • In short, Nader believes that the very act of remembering can change our memories.
  • Nader was born in Cairo, Egypt. His Coptic Christian family faced persecution at the hands of Arab nationalists and fled to Canada in 1970, when he was 4 years old
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  • Memories surrounding a major event like September 11 might be especially susceptible, he says, because we tend to replay them over and over in our minds and in conversation with others—with each repetition having the potential to alter them.
  • He attended college and graduate school at the University of Toronto, and in 1996 joined the New York University lab of Joseph LeDoux, a distinguished neuroscientist who studies how emotions influence memory.
  • Scientists have long known that recording a memory requires adjusting the connections between neurons. Each memory tweaks some tiny subset of the neurons in the brain (the human brain has 100 billion neurons in all), changing the way they communicate. Neurons send messages to one another across narrow gaps called synapses. A synapse is like a bustling port, complete with machinery for sending and receiving cargo—neurotransmitters, specialized chemicals that convey signals between neurons. All of the shipping machinery is built from proteins, the basic building blocks of cells.
  • In five decades of research, Kandel has shown how short-term memories—those lasting a few minutes—involve relatively quick and simple chemical changes to the synapse that make it work more efficiently. Kandel, who won a share of the 2000 Nobel Prize in Physiology or Medicine, found that to build a memory that lasts hours, days or years, neurons must manufacture new proteins and expand the docks, as it were, to make the neurotransmitter traffic run more efficiently. Long-term memories must literally be built into the brain’s synapses. Kandel and other neuroscientists have generally assumed that once a memory is constructed, it is stable and can’t easily be undone. Or, as they put it, the memory is “consolidated.”
  • under ordinary circumstances the content of the memory stays the same, no matter how many times it’s taken out and read. Nader would challenge this idea.
  • Work with rodents dating back to the 1960s didn’t jibe with the consolidation theory. Researchers had found that a memory could be weakened if they gave an animal an electric shock or a drug that interferes with a particular neurotransmitter just after they prompted the animal to recall the memory. This suggested that memories were vulnerable to disruption even after they had been consolidated.
  • the work suggested that filing an old memory away for long-term storage after it had been recalled was surprisingly similar to creating it the first time
  • In the winter of 1999, he taught four rats that a high-pitched beep preceded a mild electric shock. That was easy—rodents learn such pairings after being exposed to them just once. Afterward, the rat freezes in place when it hears the tone. Nader then waited 24 hours, played the tone to reactivate the memory and injected into the rat’s brain a drug that prevents neurons from making new proteins. If memories are consolidated just once, when they are first created, he reasoned, the drug would have no effect on the rat’s memory of the tone or on the way it would respond to the tone in the future. But if memories have to be at least partially rebuilt every time they are recalled—down to the synthesizing of fresh neuronal proteins—rats given the drug might later respond as if they had never learned to fear the tone and would ignore it. If so, the study would contradict the standard conception of memory.
  • When Nader later tested the rats, they didn’t freeze after hearing the tone: it was as if they’d forgotten all about it
  • After Nader’s initial findings, some neuroscientists pooh-poohed his work in journal articles and gave him the cold shoulder at scientific meetings. But the data struck a more harmonious chord with some psychologists. After all, their experiments had long suggested that memory can easily be distorted without people realizing it.
  • To Nader and his colleagues, the experiment supports the idea that a memory is re-formed in the process of calling it up. “From our perspective, this looks a lot like memory reconsolidation,” says Oliver Hardt, a postdoctoral researcher in Nader’s lab.
  • “When you retell it, the memory becomes plastic, and whatever is present around you in the environment can interfere with the original content of the memory,” Hardt says.
  • The question is whether reconsolidation—which he thinks Nader has demonstrated compellingly in rat experiments—is the reason for the distortions.
  • at the Douglas Mental Health University Institute. Alain Brunet, a psychologist, is running a clinical trial involving people with post-traumatic stress disorder (PTSD). The hope is that caregivers might be able to weaken the hold of traumatic memories that haunt patients during the day and invade their dreams at night.
  • In Brunet’s first study, PTSD patients took a drug intended to interfere with the reconsolidation of fearful memories. The drug, propranolol, has long been used to treat high blood pressure, and some performers take it to combat stage fright. The drug inhibits a neurotransmitter called norepinephrine. One possible side effect of the drug is memory loss.
  • Nine patients took a propranolol pill and read or watched TV for an hour as the drug took effect. Ten were given a placebo pill. Brunet came into the room and made small talk before telling the patient he had a request: he wanted the patient to read a script, based on earlier interviews with the person, describing his or her traumatic experience. The patients, all volunteers, knew that the reading would be part of the experiment. “Some are fine, some start to cry, some need to take a break,” Brunet says. A week later, the PTSD patients listened to the script, this time without taking the drug or a placebo. Compared with the patients who had taken a placebo, those who had taken the propranolol a week earlier were now calmer; they had a smaller uptick in their heart rate and they perspired less.
  • The treatment didn’t erase the patients’ memory of what had happened to them; rather, it seems to have changed the quality of that memory. “Week after week the emotional tone of the memory seems weaker,” Brunet says. “They start to care less about that memory.” Nader says the traumatic memories of PTSD patients may be stored in the brain in much the same way that a memory of a shock-predicting tone is stored in a rat’s brain. In both cases, recalling the memory opens it to manipulation.
  • Nader suggests that reconsolidation may be the brain’s mechanism for recasting old memories in the light of everything that has happened since. In other words, it just might be what keeps us from living in the past.
  • Elizabeth Loftus
  • Karim Nader
  • Eric Kandel
  • Brunet
    may 2010
Jacques Kerneis

L'Agence nationale des Usages des TICE - Le partage de signets pour la collaboration et... - 2 views

    • Jacques Kerneis
      Logique applicationniste ?
  • pour la
  • compétence essentielle pour appréhender les flux informationnels
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  • invite
  • peut entraîner
  • catégorisation
  • peut en outre
  • faire une mobilisation collective
  • l’usager souhaite
  • bibliothèques de liens 
  • e commenter les liens sauvegardés, ce qui donne une valeur ajoutée à ces liens et contribue à les caractérise
  • catégories
  • stockage
  • Braga
  • devant utiliser une plateforme de partage de signets durant un semestre
  • devaient
  • voir où ils en sont de leurs recherches et incite à produire un travail régulier » ;
  • uisque chaque membre a envie d’être utile à l’équipe ».
  • onfère ainsi une dimension sociale à la recherche d’informations.
  • résultats similaires
  • devaient
  • sciences physiques
  • ont collecté un nombre plus important d’informations par rapport au groupe utilisant le moteur de recherche.
  • plus d’attention aux ressources associées à des commentaires déposés par les internautes et par leurs pairs.
  • (BTS) devaient
  • le suivi du travail des élèves par leur enseignante.
  • la pertinence d’une ressource,
  • pour évaluer la répartition des tâches dans l’équipe, le choix et la pertinence de certaines ressources ou la qualité des mots clés retenus.
  • ue lorsque les élèves ne travaillent qu’avec un moteur de recherche traditionnel.
  • ouvre également la porte
  • et de ses besoins
  • niveau équivalent à la première année d’IUFM
  • ur les connaissances et compétences acquises en cours.
  • ont dû
  • Un groupe contrôle
  • Les résultats montrent que
  • impact positif
  • se rappeler
  • apacité à les relier avec des connaissances en cours d’acquisition ou déjà stabilisées
  • oblige à un effort de catégorisation et de conceptualisation, et tend à induire une lecture plus approfondie de celles-ci.
  • e partage et l’indexation de signets sont intéressants également pour des élèves de première.
  • matérialise plusieurs étapes de la recherche d’informations dans un seul et même outil.
  • et l’accompagner via un suivi individualisé.
  • ontribue à responsabiliser et impliquer les élèves dans le travail de groupe.
  • au service d’une co-exploration de l’offre informationnelle.
  • et éviter ainsi que ces bibliothèques de signets ne soient que de simples réservoirs de liens.
  • en les raccrochan
    "Le partage de signets pour la collaboration et l'apprentissage Résumé : Organiser de façon structurée des ressources sélectionnées sur le Web est une compétence essentielle pour appréhender les flux informationnels. Des recherches ont souligné qu'un usage collaboratif du partage de signets invite à une co-exploration du Web, ce qui peut entraîner l'implication forte des membres d'un groupe et mettre en œuvre un processus d'intelligence collective. La catégorisation des ressources au sein des bibliothèques de signets en ligne, via l'indexation ou les commentaires, peut en outre, aider à la conceptualisation et à l'appropriation du contenu des ressources par les apprenants. Recommandations : Encourager les élèves à commenter les ressources mises à disposition en les raccrochant à un contexte pédagogique précis. Aider les élèves à choisir les mots clés :  éviter les synonymes (il peut être intéressant ici de faire une mobilisation collective des idées au préalable); associer plusieurs mots clés pour indexer plus précisément une ressource.  Voir aussi : Témoignage - recherche sur le romantisme Témoignage - centre multimédia Thèse de Michèle Drechsler (IEN) sur Eduscol Article de Michèle Dreschler - revue Les cahiers du numériques Usages pédagogiques du « social bookmarking » Travaux personnels encadrés Utilisation pédagogique du social bookmarking lors de la recherche d'informations Médias sociaux et éducation Article de Laurence Juin, documentaliste - « Un nouvel outil au service de ma pédagogie ! » par Florence Canet * Les signets, aussi appelés "favoris" ou "marques-pages", sont des pages Web enregistrées auxquelles l'usager souhaite avoir un accès ultérieur facilité. Le partage de signets en ligne (également connu sous le terme anglais de social bookmarking) est une pratique qui permet de sauvegarder, organiser et commenter des pages Web dans une bibliothèque virtuelle créée via un
Michel Roland-Guill

Orthographic Processing in Baboons (Papio papio) - 1 views

  • Our results demonstrate that basic orthographic processing skills can be acquired in the absence of preexisting linguistic representations.
  • The computation of letter identities and their relative positions is referred to as orthographic processing, and there is a large consensus today that such processing represents the first “language-specific” stage of the reading process that follows the operations involved in the control of eye movements (bringing words into the focus of central vision) and early visual processing (enabling visual feature extraction; Fig. 1A) (1–4). In the present study, we examined whether the ability to efficiently process orthographic information can operate in the absence of prior linguistic knowledge.
  • Orthographic processing lies at the interface between the visual processing and the linguistic processing involved in written language comprehension.
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  • Dehaene and colleagues proposed that skilled reading involves an adaptation of general object-identification processes in ventral occipitotemporal brain areas to the specific characteristics of printed words
  • according to the dominant theories of reading, orthographic processing is still primarily considered to be an extension of already established linguistic skills in the domain of spoken language processing
  • We challenged the hypothesis that learning an orthographic code depends on preexisting linguistic knowledge by investigating whether nonhuman primates can learn this skill.
  • the word versus nonword discrimination could be made implicitly on the basis of statistical dependencies between letters.
  • More detailed analyses revealed that baboons were not simply memorizing the word stimuli but had learned to discriminate words from nonwords on the basis of differences in the frequency of letter combinations in the two categories of stimuli (i.e., statistical learning).
  • words that were seen for the first time triggered significantly fewer “nonword” responses than did the nonword stimuli
  • Even more striking is the strong linear relation, shown in Fig. 4, between accuracy in response to nonword stimuli and their orthographic similarity to words that the baboons had already learned. The more similar a nonword was to a known word, the more false positive responses it produced.
  • Our findings have two important theoretical implications. First, they suggest that statistical learning is a powerful universal (i.e., cross-species) mechanism that might well be the basis for learning higher-order (linguistic) categories that facilitate the evolution of natural language (18, 19). Second, our results suggest that orthographic processing may, at least partly, be constrained by general principles of visual object processing shared by monkeys and humans.
  • Our study may therefore help explain the success of the human cultural choice of visually representing words using combinations of aligned, spatially compact, ordered sequences of symbols. The primate brain might therefore be better prepared than previously thought to process printed words, hence facilitating the initial steps toward mastering one of the most complex of human skills: reading.
  • Our results indicate that baboons were coding the word and nonword stimuli as a set of letter identities arranged in a particular order. Baboons had learned to discriminate different letters from each other (letter identity) and to associate those letter identities with positional information. Their coding of the statistical dependencies between position-coded letters is reflected in (i) their ability to discriminate novel words from nonwords (i.e., generalization), (ii) the significant correlation between bigram frequency and the accuracy of responses to words, and (iii) the increase in errors in response to nonword stimuli that were orthographically more similar to known words.
Michel Roland-Guill

Share the books you read with friends and peers - Readmill - 0 views

    Et un nouveau réseau social de lecteurs à ajouter, un (que le 63ème ;) :
Michel Roland-Guill

How people read online: Why you won't finish this article. - Slate Magazine - 0 views

  • The more I type, the more of you tune out. And it’s not just me.
  • lots of people are tweeting out links to articles they haven’t fully read.
  • There’s a very weak relationship between scroll depth and sharing.
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  • articles that get a lot of tweets don’t necessarily get read very deeply.
Michel Roland

Protagonize: collaborative story & creative fiction writing community - 0 views

    "Get creative. Protagonize lets you explore your hidden writing talent."
Michel Roland-Guill

Rough Type: Nicholas Carr's Blog: Minds like sieves - 2 views

  • we may be entering an era in history in which we will store fewer and fewer memories inside our own brains.
    • Michel Roland-Guill
      conclusion un peu rapide: plutôt que moins de mémorisation ce peut être une différente forme de mémorisation, plutôt que mémorisation des faits mémorisation des lieux de stockage des faits.
  • external storage and biological memory are not the same thing
  • When we form, or "consolidate," a personal memory, we also form associations between that memory and other memories that are unique to ourselves and also indispensable to the development of deep, conceptual knowledge. The associations, moreover, continue to change with time, as we learn more and experience more. As Emerson understood, the essence of personal memory is not the discrete facts or experiences we store in our mind but "the cohesion" which ties all those facts and experiences together. What is the self but the unique pattern of that cohesion?
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  • We are becoming symbiotic with our computer tools
  • "It seems that when we are faced with a gap in our knowledge, we are primed to turn to the computer to rectify the situation."
  • "when people expect to have future access to information, they have lower rates of recall of the information itself and enhanced recall instead for where to access it."
  • we seem to have trained our brains to immediately think of using a computer when we're called on to answer a question or otherwise provide some bit of knowledge.
  • people who believed the information would be stored in the computer had a weaker memory of the information than those who assumed that the information would not be available in the computer
  • believing that one won’t have access to the information in the future enhances memory for the information itself, whereas believing the information was saved externally enhances memory for the fact that the information could be accessed, at least in general.
  • when people expect information to remain continuously available (such as we expect with Internet access), we are more likely to remember where to find it than we are to remember the details of the item.
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