10 julio 2014

El cerebro del paciente con trastorno bipolar le guía a tomar decisiones arriesgadas

Una investigación de científicos de las universidades de Manchester y Liverpool, en Reino Unido, ha demostrado que los circuitos del cerebro involucrados en buscar y vivir experiencias gratificantes están más fuertemente activados en personas con trastorno bipolar, guiándolas hacia apuestas más arriesgadas.
Este estudio, que se publicó este miércoles en la revista ‘Brain’, utilizó imágenes cerebrales para identificar las vías neuronales que son responsables de los síntomas de este trastorno. Sus resultados ayudarán a diseñar, evaluar y monitorear los tratamientos para el trastorno bipolar.
Los pacientes con trastorno bipolar experimentan episodios de depresión y manía (periodos de intensa emoción e irritabilidad que, a menudo, conducen a un comportamiento muy arriesgado) que se producen de manera imprevisible. Es una de las formas más graves y difíciles de tratar la enfermedad mental, asociada con una menor esperanza de vida, un alto riesgo de suicidio y deterioro a veces persistente del trabajo y las relaciones sociales.
The image shows an mri scan with the dorsal frontal cortex lit up in a bipolar patient.
El estudio, financiado por el ‘Medical Research Council’, se basa en las decisiones arriesgadas tomadas por pacientes bipolares. Los investigadores Liam Mason, Wael El-Deredy y Daniela Montaldi, de la Universidad de Manchester, en colaboración con Richard Bentall y Noreen O’Sullivan, de la Universidad de Liverpool, invitaron a los participantes a jugar a un juego de la ruleta en el que se hacen apuestas seguras o arriesgadas.
Los investigadores midieron la actividad cerebral mediante imágenes de resonancia magnética funcional (fMRI, por sus siglas en inglés). Sus hallazgos revelaron un predominio del ‘centro del placer’ del cerebro que nos impulsa a buscar y perseguir recompensas, respondiendo a ellas de forma automática, antes de que surta efecto el conocimiento consciente.
Esta antigua área del cerebro, llamada núcleo accumbens, fue más fuertemente activada en personas con trastorno bipolar en comparación con un grupo control sano. Otra diferencia clave surgió en la corteza prefrontal, un área recientemente evolucionada del cerebro que se asocia con el pensamiento consciente.
Al igual que el director de una orquesta, este área nos da la capacidad de coordinar las diferentes unidades y los impulsos, como reprimir nuestros impulsos cuando se enfrentan con decisiones arriesgadas, permitiendo a la gente tomar decisiones que son menos inmediatamente gratificantes, pero mejor en el largo plazo.
Los investigadores encontraron que en los participantes de control, su corteza prefrontal los guió hacia apuestas seguras y lejos de conductas arriesgadas. En el caso de las personas con trastorno bipolar, la balanza se inclinó a la inversa: hacia una mayor actividad neuronal para las apuestas arriesgadas.
“Este estudio muestra cómo podemos utilizar las nuevas herramientas de la neurociencia para entender mejor los mecanismos psicológicos que conducen a un trastorno psiquiátrico que, hasta ahora, ha sido muy difícil de entender”, resalta el profesor Richard Bentall.
A ello, el doctor Liam Mason, que ahora trabaja en el Instituto de Psiquiatría de Londres, añade: “La comprensión de cómo funciona el cerebro para regular la consecución de los objetivos nos ayudará a diseñar, evaluar y monitorear mejores terapias para el trastorno bipolar”.


06 julio 2014

Encuentran posible sitio que actúa como suiche on/off de la conciencia

Researchers May Have Discovered The Consciousness On/Off Switch

July 3, 2014 | by Justine Alford

Researchers from the George Washington University have managed to switch consciousness on and off in an epileptic woman by stimulating a single region of the brain with electrical impulses. While this is a single case study, it provides an exciting insight into the neural mechanisms behind consciousness, a subject of great interest that is poorly understood despite decades of research. The study has been published in Epilepsy & Behavior.
Consciousness is a fascinating topic that has both intrigued and puzzled scientists and philosophers for centuries. Despite significant advances in our understanding of the brain, little is known about the neural networks that underpin consciousness. However, research has hinted that consciousness is likely the result of an integration of activity from numerous different areas of the brain, marrying all of our perceptions together into one experience. But what is the central hub to this process?
A few years back, Francis Crick, one of the scientists involved in deciphering the structure of DNA, and colleague Christof Koch proposed that a brain region known as the claustrum may be at the heart of consciousness, stringing together the constant input of information arriving from different brain networks. 
Now, in the latest study, researchers demonstrate that their hypothesis might be correct after all. The scientists stumbled upon this finding whilst stimulating different areas of the brain of an epileptic woman and measuring resultant activity in order to find the epicenter of her seizures. They discovered that electrical stimulation with an electrode placed between the left claustrum and anterior-dorsal insula caused the woman to lose consciousness. She completely stopped moving, became unresponsive and her breathing slowed.
When the researchers stopped the stimulation, she regained consciousness and couldn’t remember the event. Furthermore, the effects were reproducible as the same outcome occurred each time they stimulated this region over a period of two days. To make sure they were not merely interfering with motor control or speech, they asked the woman to repeat a particular word or perform a certain movement as the stimulation commenced. The woman gradually spoke more quietly and moved less and less as she became unconscious, rather than immediately stopping, suggesting this was affecting consciousness. They also did not identify any associated epileptic activity, suggesting it was not merely a seizure.
Lead author Mohamad Koubeissi told New Scientist he believes that the results do suggest that the claustrum plays a pivotal role in consciousness. “I would liken it to a car,” he said. “A car on the road has many parts that facilitate its movement- the gas, the transmission, the engine- but there’s only one spot where you turn the key and it all switches on and works together. So while consciousness is a complicated process created via many structures and networks- we may have found the key.”
However, some experts have highlighted the difficulties in interpreting findings from only 1 case study. Furthermore, the woman was missing part of her hippocampus and therefore is not representative of a “normal” brain. Still, it is agreed that the study is important and certainly informative, especially since the woman was awake in the study rather than asleep or in a coma like in many other studies.
Koch also expressed interest in the research. “This study is incredibly intriguing but it is one brick in a large edifice of consciousness that we’re trying to build,” he said.
[Via New Scientist and Epilepsy & Behavior] [Header image "Working Brain" by Gontzal del Caño, via Flickr, used in accordance with CC BY-NC-SA 2.0)

Read more at http://www.iflscience.com/brain/researchers-may-have-discovered-consciousness-onoff-switch#MdWex66wZE6z9Uu4.99