archivo

Neurociencias

Uno de los casos mas sonados en el área de las neurociencias en el 2011 es el caso de las siamesas (craneopagos) Tatiana Y Krista Hogan que comparten todo, incluso sus pensamientos. Imágenes cerebrales por medio de Resonancia Magnética (IRM) revelan una anatomía cerebral única, ya que no hay casos parecidos reportados por literatura medica hasta el momento. La IRM revea una linea tenue en la zona talamica que el Neurocirujano Douglas Cochrane ha denominado  “puente talamico” y se piensa que por medio de éste puente el tálamo de Krista esta unido al tálamo de Tatiana.

La zona que se indica con una flecha corresponde al tálamo.

Debido a esta unión se ha demostrado que que los estímulos sensoriales que una niña recibe la otra tambien la siente.

Este es un articulo publicado por el NY times es muy interesante en términos de neurofisiología.

Anuncios

Toda experiencia está condenada a desaparecer. Esto plantea una pregunta fascinante: ¿existe un lugar secreto donde nuestros días pasados se reúnan? Como preguntó el místico medieval: “¿A dónde va la luz cuando se apaga la vela?”. Creo que existe un lugar secreto de reunión para los días desaparecidos. El nombre de ese lugar es Memoria.”

Probablemente nuestras memorias sean lo mas atesorable que nos queda con el paso de los años. Hay grandes textos a cerca de la memoria, mecanismos fisiologicos, neuromecanismos y patologias relacionadas, entre las que encuentro mas valiosas son las de Jonah Lehrer y Oliver Sacks.

Jonah Lehrer escribe este curioso articulo a cerca de las falsas Memorias.

Ads Implant False Memories.

My episodic memory stinks. All my birthday parties are a blur of cake and presents. I’m notorious within my family for confusing the events of my own childhood with those of my siblings. I’m like the anti-Proust.

And yet, I have this one cinematic memory from high-school. I’m sitting at a Friday night football game (which, somewhat mysteriously, has come to resemble the Texas set of Friday Night Lights), watching the North Hollywood Huskies lose yet another game. I’m up in the last row of the bleachers with a bunch of friends, laughing, gossiping, dishing on AP tests. You know, the usual banter of freaks and geeks. But here is the crucial detail: In my autobiographical memory, we are all drinking from those slender glass bottles of Coca-Cola (the vintage kind), enjoying our swigs of sugary caffeine. Although I can’t remember much else about the night, I can vividly remember those sodas: the feel of the drink, the tang of the cola, the constant need to suppress burps.

It’s an admittedly odd detail for an otherwise logo free scene, as if Coke had paid for product placement in my brain. What makes it even more puzzling is that I know it didn’t happen, that there is no way we could have been drinking soda from glass bottles. Why not? Because the school banned glass containers. Unless I was willing to brazenly break the rules — and I was way too nerdy for that — I would have almost certainly been guzzling Coke from a big white styrofoam container, purchased for a dollar from the concession stand. It’s a less romantic image, for sure.

So where did this sentimental scene starring soda come from? My guess is a Coca-Cola ad, one of those lavishly produced clips in which the entire town is at the big football game and everyone is clean cut, good looking and holding a tasty Coke product. (You can find these stirring clips on YouTube.) The soda maker has long focused on such ads, in which the marketing message is less about the virtues of the product (who cares if Coke tastes better than Pepsi?) and more about associating the drink with a set of intensely pleasurable memories.

A new study, published in The Journal of Consumer Research, helps explain both the success of this marketing strategy and my flawed nostalgia for Coke. It turns out that vivid commercials are incredibly good at tricking the hippocampus (a center of long-term memory in the brain) into believing that the scene we just watched on television actually happened. And it happened to us.

The experiment went like this: 100 undergraduates were introduced to a new popcorn product called “Orville Redenbacher’s Gourmet Fresh Microwave Popcorn.” (No such product exists, but that’s the point.) Then, the students were randomly assigned to various advertisement conditions. Some subjects viewed low-imagery text ads, which described the delicious taste of this new snack food. Others watched a high-imagery commercial, in which they watched all sorts of happy people enjoying this popcorn in their living room. After viewing the ads, the students were then assigned to one of two rooms. In one room, they were given an unrelated survey. In the other room, however, they were given a sample of this fictional new popcorn to taste. (A different Orville Redenbacher popcorn was actually used.)

One week later, all the subjects were quizzed about their memory of the product. Here’s where things get disturbing: While students who saw the low-imagery ad were extremely unlikely to report having tried the popcorn, those who watched the slick commercial were just as likely to have said they tried the popcorn as those who actually did. Furthermore, their ratings of the product were as favorable as those who sampled the salty, buttery treat. Most troubling, perhaps, is that these subjects were extremely confident in these made-up memories. The delusion felt true. They didn’t like the popcorn because they’d seen a good ad. They liked the popcorn because it was delicious.

The scientists refer to this as the “false experience effect,” since the ads are slyly weaving fictional experiences into our very real lives. “Viewing the vivid advertisement created a false memory of eating the popcorn, despite the fact that eating the non-existent product would have been impossible,” write Priyali Rajagopal and Nicole Montgomery, the lead authors on the paper. “As a result, consumers need to be vigilant while processing high-imagery advertisements.”

At first glance, this experimental observation seems incongruous. How could a stupid commercial trick me into believing that I loved a product I’d never actually tasted? Or that I drank Coke out of glass bottles?

The answer returns us to a troubling recent theory known as memory reconsolidation. In essence, reconsolidation is rooted in the fact that every time we recall a memory we also remake it, subtly tweaking the neuronal details. Although we like to think of our memories as being immutable impressions, somehow separate from the act of remembering them, they aren’t. A memory is only as real as the last time you remembered it. What’s disturbing, of course, is that we can’t help but borrow many of our memories from elsewhere, so that the ad we watched on television becomes our own, part of that personal narrative we repeat and retell.

This idea, simple as it seems, requires us to completely re-imagine our assumptions about memory.  It reveals memory as a ceaseless process, not a repository of inert information. The recall is altered in the absence of the original stimulus, becoming less about what we actually remember and more about what we’d like to remember. It’s the difference between a “Save” and the “Save As” function. Our memories are a “Save As”: They are files that get rewritten every time we remember them, which is why the more we remember something, the less accurate the memory becomes. And so that pretty picture of popcorn becomes a taste we definitely remember, and that alluring soda commercial becomes a scene from my own life. We steal our stories from everywhere. Marketers, it turns out, are just really good at giving us stories we want to steal.

via Ads Implant False Memories | Wired Science | Wired.com.

letras y numeros

Adam Hadhazy  colaborador de Live Science escribe el articulo Live’s extremes Math vs Language, que vale la pena leer para entender un poco mas a cerca de dislexia y discaluculia.

Do you know what “abecedarian” means? What about the solution to 250 x 11?

Most people would agree they are better at verbal or math subjects in school, as grades usually do attest. Highly intelligent individuals often do well in both subjects, and may know the answers to both questions above, lickety-split, while less intelligent people can struggle. But a minority of us excels in the language department and bombs at mathematics, or vice versa.  

As an adjective, abecedarian refers to something relating to the alphabet; 2,750 is the solution to the equation.)

These extremes in ability speak (or equate) to the very makeup of our brains. “The brain systems for maths and language are quite different,” said Brian Butterworth, emeritus professor of cognitive neuropsychology at University College London, using British English’s dialect for “math.” “So perhaps it is not surprising that these two capacities are rather independent.”

By learning more about the regions of our brains responsible for language and math processing, researchers hope to someday better help those with severe deficits, such as in reading ability, called dyslexia, and general numeracy, called dyscalculia.

Wordly wise

Verbal ability — reading, writing and speaking — arises from across much of our brain, requiring key elements to harmonize.

When we read, for example, the “ventral stream” located at the rear of the head and involved in object recognition becomes active. Parietal (on the side) and frontal regions activate as well, as revealed by neuroimaging studies. These brain areas figure out the “sounds” of letters and the semantics of words. [Inside the Brain: A Journey Through Time]

In about 5 percent to 12 percent of the population with dyslexia, reading is fraught with difficulty. Spelling is sometimes a problem, too. An unknown percentage of the population also grapples with so-called dysgraphia, an inability to write. Dysgraphics make ill-formed letters with improper spacing, or produce the wrong word for a concept, such as “girl” or “boy” instead of “child.”

Brain injuries can also cause these verbal deficits, same as with math. Genetics, though, clearly has a profound impact, based on learning disabilities running in families and genetic ailments that produce clear deficits.

In the case of well-studied dyslexia, several candidate genes have emerged that code for how neurons in the brain form interconnections.

“The idea is that throughout gestation and early development, neurons traveling to where they should be going don’t reach their targets,” said Guinevere Eden, director of the Center for the Study of Learning at Georgetown University Medical Center, who studies dyslexia.

A head for numbers

A typically separate group of people has trouble not with reading and writing, but with learning basic mathematics. Dyscalculia affects some 6 percent to 8 percent of the world population, studies suggest. As with dyslexia, something of a genetic component exists, with identical twins sharing dyscalculia almost 60 percent of the time. [Seeing Double: 8 Fascinating Facts About Twins]

Several brain areas activate when subjects perform calculations, in particular the intraparietal sulcus, located at the top-back area of our heads.

“This appears to be the ‘math center’ of the brain,” said Melissa Libertus, a postdoctoral fellow in the department of psychological and brain sciences at Johns Hopkins University. “If this part of the brain has a problem, then those people have math problems.”

ABCs or 123s

Libertus has just published a paper showing that preschoolers have varying degrees of “number sense,” or an innate ability to estimate quantities. It’s likely, Libertus said, that people with higher inborn skills perform better at math throughout their lives. Similarly, Eden has studied children with precocious reading abilities, showing that some of us just have a knack.

On the other hand, being born with dyslexia or dyscalculia, does not necessarily produce a math or language person. In this way, upbringing and education frequently lead to language or math preferences based on innate strengths and weaknesses.

“Of course, environment and experience play a major role,” Butterworth said. Parents who have a lot of books around the house might encourage a child to get more into reading and writing, whereas math games promote doing sums instead.

Human calculators and polyglots

Although our brains are evolutionarily hard-wired for speech and a basic sense of numbers, we must be taught to read, write and do arithmetic. And regardless of one’s natural abilities, practice — to an extent — can make perfect.

Many prodigious “human calculators,” for example, admit to being obsessed with numbers, thinking about and working with them all day. Similarly, polyglots such as Emil Krebs, a German man who claimed mastery of 68 languages, must study hard to become fluent in non-native tongues.

Supporting this “practice makes perfect” view is that fact that language or math abilities are not tied to IQ scores. Shakuntala Devi, an Indian woman, astoundingly multiplied two 13 digit numbers in her head in 28 seconds, yet possessed an average IQ.

Math “savants” go even further, such as Dustin Hoffman’s character in “Rain Man.” These rare individuals perform feats of mathematical wizardry but have terrible verbal skills and low IQ scores.

Ultimately, markedly skewed abilities in language and math come about from a confluence of factors, researchers agree. Genes, development and personal zeal all determine our letter grades and where we fall on the number line.

via Life’s Extremes: Math vs. Language | Dyscalculia & Dyslexia | IQ Scores & Verbal & Math Skills | Nature vs. Nurture | LiveScience.