01 octubre 2007

Juegos por computadora parecen prevenir el declive mental

Traducido por Ruben Carvajal Santana de http://www.timesonline.co.uk/tol/news/uk/article2327835.ece

Men playing computer games

La baronesa Susan Greenfield, neurocientífica, directora científica de la institución real de Gran Bretaña, dice que el concentrarse en la buena salud es no es suficiente preparación para la vejez. "Hay que preocuparse por preservar el cerebro también," dijo. "Ahora hay buena evidencia científica para demostrar que ejercitar el cerebro puede protegerlo contra la declinación por la edad."

En una reciente investigación, conducida en el centro médico de Sourasky en la universidad de Tel Aviv en Israel, se les pidió a 121 voluntarios -mayores de 50 años- pasar 30 minutos, tres veces por semana, en la computadora, durante dos años.

Los resultados fueron lanzados en la 18va Conferencia International sobre Alzheimer y Parkinson en Salzburgo, Austria, demostraron que mientras que todos los voluntarios se beneficiaron al usar juegos de computadora, y algunos "mejoraron perceptiblemente mejor su memoria a corto plazo, aprendizaje visual-espacial y la atención enfocada".

Greenfield, que también trabaja en un laboratorio de la universidad de Oxford que investiga las causas de las enfermedades degenerativas del cerebro tales como Alzheimer. "Está claro que no hay droga en el horizonte para tratar el Alzheimer o la declinación mental relativa a la edad, así que estimular el cerebro parece ofrecer una manera de retrasar estos cambios," dijo.

28 septiembre 2007

TMS, estimulación magnética transcraneal

Neuroscientists connect neural activity and blood flow in new brain stimulation technique

UC Berkeley News

– Neuroscientists at the University of California, Berkeley, have for the first time measured the electrical activity of nerve cells and correlated it to changes in blood flow in response to transcranial magnetic stimulation (TMS), a noninvasive method to stimulate neurons in the brain.

Their findings, reported in the Sept. 28 issue of the journal Science, could substantially improve the effectiveness of brain stimulation as a therapeutic and research tool.

visual cortex during transcranial magnetic stimulation
Illustration of the visual cortex during transcranial magnetic stimulation (TMS). In this non-invasive brain stimulation technique, pulses of current (arrows) are passed through a figure-eight shaped coil placed above the scalp. The induced electric field elicits long-lasting alterations in neural activity which can be measured with blood flow-based imaging methods. (Elena Allen/UC Berkeley)
With technological advances over the past decade, TMS has emerged as a promising new tool in neuroscience to treat various clinical disorders, including depression, and to help researchers better understand how the brain functions and is organized.

TMS works by generating magnetic pulses via a wire coil placed on top of the scalp. The pulses pass harmlessly through the skull and induce short, weak electrical currents that alter neural activity. Yet the relative scarcity of data describing the basic effects of TMS, and the uncertainty in how the method achieves its effects, prompted the researchers to conduct their own study.

"There are potentially limitless applications in both the treatment of clinical disorders as well as in fundamental research in neuroscience," said Elena Allen, a graduate student at UC Berkeley's Helen Wills Neuroscience Institute (HWNI) and co-lead author of the study. "For example, TMS could be used to help determine what parts of the brain are used in object recognition or speech comprehension. However, to develop effective applications of TMS, it is first necessary to determine basic information about how the technique works."

Other techniques for studying neural activity in humans, such as functional magnetic resonance imaging (fMRI) or electroencephalogram (EEG), only measure ongoing activity. TMS, on the other hand, offers the opportunity to non-invasively and reversibly manipulate neural activity in a specific brain area.

In a set of experiments, the researchers used TMS to generate weak, electrical currents in the brain with quick 2- to 4-second bursts of magnetic pulses to the visual cortex of cats. Direct measurements of the electrical discharge of nerve cells in the region in response to the pulses revealed that TMS predictably caused an initial flurry of neural activity, significantly increasing cell firing rates. This increased activity lasted 30 to 60 seconds, followed by a relatively lengthy 5 to 10 minutes of decreased activity.

What the researchers were able to determine for the first time was that the neural response to TMS correlated directly to changes in blood flow to the region. Using oxygen sensors and optical imaging, the researchers found that an initial increase in blood flow was followed by a longer period of decreased activity after the magnetic pulses were applied.

"This long-lasting suppression of activity was surprising," said Brian Pasley, a graduate student at HWNI and co-lead author of the study. "We're still trying to understand the physiological mechanisms underlying this effect, but it has implications for how TMS could be used in clinical applications."

The critical confirmation of the connection between blood flow and neural activity means that researchers can use TMS to alter neural activity, and then use fMRI, which tracks blood flow changes, to assess how the nerve cells respond over time.

"One of the most exciting applications of TMS is the ability to non-invasively modify neural activity in specific ways," said Pasley. "The brain is malleable, so brain stimulation may be used to alter and promote specific functions, like learning and memory, or suppress abnormal activity that underlies neurological disorders. If we can figure out the right ways to stimulate the brain, TMS will likely be useful in attempts to improve neural function."

The researchers noted that one of the difficulties in using TMS for specific applications is the fact that its effects vary in different brain regions and individuals.

"Using TMS is inherently challenging because its neural effects can be so variable," said Ralph Freeman, UC Berkeley professor of vision science and optometry and principal investigator of the study. "Fortunately, we can determine empirically what the end result is by making measurements with fMRI. This should be valuable to clinicians who must evaluate the effectiveness of a stimulation treatment. In turn, fMRI may serve as a guide to determine adjustments in treatment parameters."

The study was also co-authored by Thang Duong, a UC Berkeley graduate student in vision science. The National Eye Institute of the National Institutes of Health and the National Science Foundation helped support this research.

26 septiembre 2007

El experimento psicológico más importante nunca hecho

The Most Important Psychology Experiment That's Never Been Done

By Brandon Keim September 25, 2007 | 4:57:29 PM

Tunnel What's the most important psychology experiment that hasn't been done?

The British Psychological Society asked this question of leading psychologists and bloggers, and is collecting the responses on their blog. One of the more interesting, suggested by Susan Blackmore: watching death.

The most important experiment that’s never been done is to take fMRI or PET scans of people as they die; either those who really do go on to die, or those who suffer clinical death but are resuscitated. If this were done we would be able to test theories about how NDEs and mystical experiences are generated in the dying brain, and answer questions about the timing of the experiences. Perhaps even this would not resolve the final question once and for all, but it would certainly bring us a lot closer to knowing what happens when we die.

And why has it not been done? Because when someone is dying it is far more important to try to save their life than to do a scientific experiment. Nevertheless it could be done, and I hope that one day the technology will be so unobtrusive and easy to use that the ethical problem will disappear and we will be able to watch the dying brain as easily as we can now watch the living brain.


23 septiembre 2007

El olor de la androsterona

September 19, 2007
Molecular biology

Whether a man smells sweet or stinky is in the odorant receptor of the beholder

Sophie L. Rovner

Genetic differences determine whether a component of male body odor smells like sweat, vanilla, or nothing at all, according to newly published research. The component is androstenone, a steroid derived from testosterone that is present in sweat.

To some people, androstenone smells pleasant, with a sweet, floral, or vanilla-like scent. Others find the compound's odor offensive and liken it to sweat or urine. A third group can't even smell the compound. The wide variability in people's perception of androstenone is due in large part to slight genetic variations that affect the odorant receptor OR7D4, report Leslie B. Vosshall, an associate professor who heads Rockefeller University's Laboratory of Neurogenetics & Behavior; Hiroaki Matsunami, an assistant professor of molecular genetics and microbiology at Duke University Medical Center; and their colleagues (Nature, DOI: 10.1038/nature06162).

The researchers determined that people who find androstenone unpleasant have two single-nucleotide polymorphisms in the gene for the receptor which is expressed in sensory cells in the nose. In vitro studies showed that these mutations severely impair the receptor's function.

Matsunami says the work represents the first demonstration of a link between the performance of a human odorant receptor and "how that odor is perceived.” He adds that "the sex-steroid odors that we tested in humans act as pheromones in pigs, and there has been debate whether these same chemicals act similarly in humans. There is evidence that smelling these odors can affect the mood and physiological state of both men and women.”

21 septiembre 2007

Por qué las cosas huelen

Why Stuff Stinks: Secret Sniffed Out

By Dave Mosher, LiveScience Staff Writer

posted: 21 September 2007 08:36 am ET

Our noses can quickly distinguish a pleasant smell and a stench, but until now the chemical cues that help us make such decisions had not been understood.

Researchers have found that heavier, more spread-out molecules tend to smell worse than lighter, more compact molecules, although exceptions to the rule exist. The finding can be used to predict how good or bad a molecule smells before anyone takes a whiff of it.

Rehan Khan, a neuroscientist at the University of California in Berkeley, thinks evolution selected for pleasantness of smell as a gut reaction to guide us through our environments.

"People can tell you right away whether something smells bad or good, but they're bad at naming the scent," Khan said. "Evolution probably latched onto the most efficient cues, like how the eye uses the wavelength of light to pick out colors."

Khan and his colleagues' findings are detailed in a recent issue of the Journal of Neuroscience.

Molecular breakdown

To find the nose's shortcuts for discerning good smells from bad, Khan and his team looked at more than 1,500 different properties of about 150 molecules, then compared them to professional "smelling assessments" of the substances.

In the end, molecular weight and electron density best correlated with pleasantness. Butanol, for example, is an "electron-dense" and spread-out molecule that stinks like rotting wood, while limonene—a compact but lightweight molecule—smells like citrus.

"We think, evolutionarily, that our bodies have settled on this handful of properties to distinguish good smells from bad ones for a reason," Khan told LiveScience, but admitted that he's uncertain why the brain and nose evolved sensitivity to the molecular properties that they did.

"What we do know is that chemicals perceived as less pleasant are generally not useful to us, and can even be harmful," he said.

Smell this

Putting their new model to the test, Khan and his colleagues predicted how good or bad 27 chemicals not previously assessed by experts smelled across American, Jewish-Israeli and Arab-Israeli cultures.

Khan and his team's model, it turns out, correctly placed about 30 percent of the chemicals in an ordered list of bad-smelling to pleasant-smelling molecules. He explained that the number may appear low, but it's relatively and statistically high given the differences in cultural upbringing and complexity of our smelling abilities.

"When we presented the preliminary results at a conference, a fragrance company said they flat-out didn't believe us," he said. The wary corporation sent his team 20 new molecules for the team to predict the pleasantness of, and when they returned their results, he said the company was "quite surprised."

Professional noses

Khan said the U.S. scent-manufacturing industry, which designs and produces the scents in everyday products such as food, perfumes and candles, is a multi-billion-dollar-a-year business.

But the companies who design and make the compounds rely on highly-trained and expensive professional smellers, called "noses," to assess them.

Khan thinks if his team's model could help design pleasant-smelling chemicals from the get-go and cut back the reliance on human noses.

"We can now use chemistry to predict the perception of the smells of new substances," Khan said. "This may really help to design scents other than by trial-and-error, which is an extremely expensive process."

Cómo percibimos los olores

How We Smell

By Corey Binns, Special to LiveScience

posted: 22 May 2006 08:37 am ET

Your nose is one powerful protrusion. Whether it's a big honker or a little button, if it is working correctly you can sense a skunk from only 0.000,000,000,000,071 of an ounce of offensive spray.

Animals can trace even tinier trails. Male luna moths, for example, track females from 5 miles away.

Such nosiness is important for the survival of almost all creatures: to find food, avoid being eaten, and pick proper mates. It warns us about rotten milk, a burning house, or an unhappy skunk, and can turn our attention to attractive potential dates.

Nosing around

Despite its value, scientists knew little about how we sensed scents before the 2004 Nobel Prize winners took a jab at it.

Know Your Noses

Guess who these famous honkers belong to, then click to see the full pictures. (Hint: None of these is attached to Gerard Depardiu or Pinocchio.)

In 1991, laureates Richard Axel of Howard Hughes Medical Institute and Linda Buck at the Fred Hutchinson Cancer Research Center discovered about 1,000 genes that encode for olfactory receptors inside the human nose. They also found that each receptor is tuned for only a small number of odors.

Researchers recently determined which receptors in a fruit fly detect which specific odors. They plotted each receptor to form an entire map of where the fly senses each scent.

"The results of our analysis allow us to make predictions about which odors smell alike to an animal, and which smell different," said Yale University molecular biologist John Carlson who worked with then-grad student Elissa Hallem, now a molecular biologist at the California Institute of Technology.

Their findings are published in the April issue of the journal Cell.

Take a deep breath

Although we don't yet have a scent map for humans, thanks to Axel and Buck, scientists know how you smell.

Take a deep breath. Air is sucked up into your nostrils over bony ridges called turbinates, which add more surface area to your sniffer. The air travels over millions of olfactory receptor neurons that sit on a stamp-size sheet, the olfactory epithelium, on the roof of the nasal cavity. Odor molecules in the air stimulate and inhibit the receptors.

Each aroma sets off a signal made by the receptors that travels along the olfactory nerve to the olfactory bulb. The olfactory bulb sits underneath the front of your brain. Signals from the bulb tell your brain what reeks.

Humans can recognize 10,000 different odors. However, no two people sense anything the same.

Good weather for smelling

Several factors, including genes, skin type, and diet are related to how smells smell. Even the weather can alter an odor.

  • When we're hungry, our smell sense grows stronger
  • Women have keener whiffers than men and like the smell of a symmetrical man best.
  • At certain times of the month, men say the scent of a woman is more attractive.
  • Our schnozzes are at their worst in the mornings, improving as the day goes on.

Some people endure long-term proboscis problems.

Smell disorders most often stem from injuries to the head and upper respiratory infections. Other causes include hormonal disturbances, dental problems, and exposure to chemicals such as insecticides and solvents can also cause smell disorders. Radiation for treating head or neck cancer can create smelling problems as well.

A nose that's in less than tip-top condition can affect taste buds too. Researchers say 80 percent of the flavors we taste come from what we smell, which is why foods become relatively flavorless when we're plugged up.

19 septiembre 2007

El brócoli y la barrera hematoencefálica

De acuerdo a un estudio aparecido en el Journal of Neuroscience (Jing Zhao, Anthony N. Moore, John B. Redell, and Pramod K. Dash) el brócoli puede ayudar en la protección del cerebro. La conclusión se obtuvo de un estudio realizado con una molécula llamada sulforaphane, que se encuentra presente en el brócoli, que ayuda a incrementar la actividad de la barrera hematoencefálica cuando ésta se encuentra dañada. El estudio se hizo en animales de laboratorio pero pudiese extrapolarse a humanos.

función principal de la barrera hematoencefálica es proteger al cerebro al prevenir la entrada de sustancias químicas peligrosas que se encuentren en la sangre. La forma como funciona el sulforaphane es atenuando la pérdida de las proteínas citoprotectivas de la barrera hematoencefálica que son las que mantienen la integridad de la misma. Estas proteínas suelen declinar después de una lesión. El sulforaphane además de disminuir la pérdida de estas proteínas al incrementar la actividad de un factor llamado Nrf2 y los elementos de respuesta antioxidante (ARE), también ayudó a disminuir la pérdida de céulas endoteliales y redujo la incidencia de daños similares por permeabilidad de la membrana y edema cerebral.

Traducido por Rubén Carvajal Santana de http://www.nutraingredients.com/news/ng.asp?n=79886-broccoli-cruciferous-vegetables-superfoods

11 septiembre 2007

Neurobiología de la política

Explorando la neurobiología de la política, científicos en la universidad de Nueva York y UCLA parecieran haber encontrado que los liberales toleran la ambigüedad y el conflicto mejor que los conservadores debido a la forma como funcionan sus cerebros.

En un experimento divulgado el en la revista Nature Neuroscience (9 September 2007; | doi:10.1038/nn1979) , Amodio y colaboradores, de la universidad de Nueva York y UCLA sugieren que la orientación política pareciera estar relacionada con las diferencias en cómo el cerebro procesa la información.

Los conservadores tenderían a ser más estructurados y persistentes en sus juicios mientras que los liberales serían más abiertos a las nuevas experiencias. El estudio encontró que esos rasgos no se confinan a las situaciones políticas sino también a las decisiones diarias.

Los resultados parecen demostrar que “hay dos estilos cognoscitivos -- un estilo liberal y un estilo conservador,” dijo el Dr. Marco Iacoboni, neurólogo de UCLA.

Los participantes eran los estudiantes universitarios que se definían a sí mismos como “muy liberales” o “muy conservadores.” Los mandaron a golpear ligeramente un teclado cuando apareciera una M en el monitor de la computadora y refrenarse de golpear ligeramente cuando vieran una W.

Conectaron a cada participante a un electroencefalograma que registró la actividad en la corteza anterior del cingulado, la parte del cerebro que detecta los conflictos entre una tendencia habitual (presionar una tecla) y una respuesta más apropiada (no presionar la tecla). Los liberales tenían más actividad en esa zona cerebral e incurrieron en menos equivocaciones que los conservadores cuando vieron una W. Los liberales y los conservadores eran igualmente exactos en el reconocimiento de la M.

Los investigadores consiguieron los mismos resultados cuando repitieron el experimento al revés, pidiendo que otro grupo de participantes golpee ligeramente cuando apareciera la W.

Frank J. Sulloway, investigador en el instituto de UC Berkeley de la personalidad, dijo que los resultados “proporcionaron una demostración elegante que las diferencias individuales en una dimensión conservador-liberal están relacionadas fuertemente con la actividad del cerebro.”

Analizando los datos, los liberales tenían 4.9 veces más probabilidad que los conservadores de demostrar actividad en los circuitos del cerebro que se ocupan de conflictos.

Sulloway dijo que los resultados podrían explicar por qué el presidente Bush demostró una posición única con respecto a la guerra de Iraq y por qué alguna gente percibió al senador John F. Kerry, el demócrata liberal de Massachusetts que opuso Bush en la campaña presidencial del 2004, como ambivalente por cambiar su posición sobre el conflicto.

De acuerdo el estudio, los liberales podían aceptar más fácilmente nuevas ideas sociales, científicas o religiosas. “Hay suficientes datos en la historia de la ciencia que demuestran que los liberales sociales y políticos tienden de hecho a apoyar revoluciones importantes en la ciencia,” dijo Sulloway, que ha escrito sobre la historia de la ciencia y ha estudiado diferencias del comportamiento entre los conservadores y los liberales.

David Amodio, profesor auxiliar de la psicología en la universidad de Nueva York, ha señalado que este estudio solo analiza una estrecha gama del comportamiento humano y que sería un error concluir que existe una orientación política que sea mejor. La tendencia de conservadores a bloquear la información innecesaria podría ser algo bueno, dependiendo de la situación, él dijo.

La orientación política, observó, ocurre a lo largo de un espectro, y las posiciones respecto a ediciones específicas, tales como impuestos, son influenciadas por muchos factores, incluyendo la educación y la abundancia. Algunos liberales se oponen a impuestos más altos y algunos conservadores favorecen las derechos del aborto.

Amodio se pregunta: "¿Significa esto que los liberales y los conservadores nunca se van a poner de acuerdo, o será que el estudio ha encontrado una razón por la cual tienden a no llevarse bien?"

Traducido por Rubén Carvajal Santana de:
Los Angeles Times


24 agosto 2007

No es telepatía, es tecnología

El científico John P. Donoghue gana premio de neurociencias.
- 20 Ago de 2007

El premio de K.J. Zülch, el honor más alto de Alemania para la investigación neurológica básica, será concedido al neurocientífico de Brown University, John P. Donoghue, en una ceremonia del 31 Ago de 2007 en Colonia, Alemania.

El premio de Zülch reconoce logros excepcionales en la investigación neurológica básica. Donoghue fue reconocido para su investigación sobre cómo el cerebro traduce el pensamiento en acción. Su trabajo ha dado lugar a un nuevo implante del cerebro que ha permitido que la gente con parálisis pueda mover el cursor de la computadora, controlar su silla de ruedas o hacer funcionar un brazo robótico - con pensamientos solamente.

Concedido por la fundación de Gertrud Reemtsma a través de la sociedad máxima de Planck, han concedido un líder en ciencia y la investigación de la tecnología, el premio a los innovadores de la neurología desde 1990.

Más allá de Zülch los ganadores premiados incluyen a laureado Stanley Prusiner, M.D. Nobel, que descubrió las proteínas infecciosas conocidas como prions; Nikos Logothetis, pionero en el uso de resonancia magnética funcional en la investigación de visión; SAM Berkovic, que determinó la base genética de la epilepsia; y Fred Gage, que ayudó a descubrir que el cerebro adulto es capaz de producir células nuevas.

Cada año, dos científicos reciben el premio de Zülch. Donoghue comparte la concesión 2007 con otro líder en neurotecnología, Graeme Clark inventor del implante coclear. Como de costumbre, Donoghue y Clark compartirán el premio de 50.000 euros, cerca de $68.300.

De acuerdo a Konstantin Hossmann, director del instituto máximo de Planck para la investigación neurológica en Colonia: "El trabajo de Juan Donoghue ofrece importantes revelaciones acerca del cerebro humano y de cómo aprovechar su energía de mejorar las vidas de la gente con lesión de la médula espinal e impedimentos motores severos”. “Ésta es una investigación excepcional con verdadero potencial de cambiar vidas.”

John P. Donoghue es director del programa de la ciencia de cerebro en Bronw University, es un líder en la investigación y el desarrollo del neuroprosthesis.

El trabajo del laboratorio de Donoghue se centra en entender cómo las redes de neuronas representan y procesan la información compleja usada en la fabricación del movimiento voluntario experto. Donoghue combinó el conocimiento de sus experimentos con avances técnicos acerca de cómo el cerebro graba la información desarrollada en su laboratorio, para crear un neuroteclogía con una promesa imponente: devolverle el movimiento a la gente con parálisis.

Traducido por Rubén Carvajal Santana de:
FirstScience News
del 24 de agosto de 2007