RODOLFO LLINAS

Autor: Carlos Enrique Parra Bösenberg (especial para Universia)

Considerado como uno de los padres de las neurociencias modernas, el colombiano Rodolfo Llinás Riascos se ubica en la cima de la investigación científica en el mundo. Cuarenta años estudiando el cerebro humano y el funcionamiento de las neuronas le han valido cinco doctorados Honoris Causa, así como un sinnúmero de premios y reconocimientos.

Perfil elaborado en noviembre de 2005

El cerebro es el órgano vital más importante que tenemos los seres vivos, ya que registra toda la existencia. Retiene, recuerda y asocia, nos dice qué hacer y cómo, nos da la capacidad de soñar, es nuestra conciencia, determina quiénes somos y en qué nos convertiremos, nos guía si estamos en peligro o cuando experimentamos alguna sensación agradable, reconocemos el mundo exterior a través suyo y efectuamos todas nuestras acciones de acuerdo con sus órdenes.

“La comunicación neuronal es la encargada de construir nuestra vida, lo que es demostrable hoy en día por medio de aparatos con altísimos niveles tecnológicos como el electroencefalógrafo, el cual es capaz de medir y registrar la actividad y funciones del cerebro”, explica el científico colombiano Rodolfo Llinás.

De niño, creció en un ambiente que le permitió desarrollar la creatividad, el pensamiento lógico y el razonamiento por inducción y deducción, postulados que hoy defiende como único camino para alcanzar una buena educación en las escuelas y colegios y para que los jóvenes desarrollen niveles de comprensión lógica para desenvolverse mejor en el mundo.

Desarmaba todo cuanto podía para saber cómo funcionaban los objetos, siempre motivado por su curiosidad insaciable y la complicidad de su padre y de su abuelo, quienes le abrieron las puertas del universo científico al llevar a la cotidianidad del hogar los temas de la medicina y de la psiquiatría, que eran sus respectivas profesiones. Ambos se encargaron de darle los espacios para desarrollar su inquietud personal sobre el funcionamiento del cuerpo, de la mente humana y de las causas y efectos de los fenómenos naturales.



Dr. Llinás, the chairman of neuroscience and physiology at the N.Y.U. School of Medicine, believes that abnormal brain rhythms help account for a variety of serious disorders, including Parkinson’s disease, schizophrenia, tinnitus and depression. His theory may explain why the technique called deep brain stimulation — implanting electrodes into particular regions of the brain — often alleviates the symptoms of movement disorders like Parkinson’s.

The theory is far from widely accepted, and most neurosurgeons say the mechanisms behind deep brain stimulation remain a mystery. Still, surgeons like Dr. Kelly are excited about the research, saying it suggests new targets for treating a variety of disorders.

“It’s a mystery to me why it took me so long to get what Rodolfo was saying,” Dr. Kelly said. “I’d like to latch on to the excuse that I was too busy. In truth, I was too dumb to listen. Now I tell my younger colleagues, ‘Listen to this man.’ He’s on to something that can revolutionize neurosurgery and our understanding of how the brain works.”

Dr. Llinás (pronounced yee-NAHS), born in Colombia 73 years ago, has long followed his own instincts.

Unlike neuroscientists who study the brain’s outer layer, or cortex, he has focused his attention on the thalamus, a paired structure in the midbrain. He has found that each walnut-size thalamus has 30 or more nuclei, each of which specializes in one type of information collected from the senses — sights, sounds, movements, external touches, internal feelings and so on.

Each nucleus sends its message to a specific area of the cortex for initial processing. But then the information is shuttled back down to the thalamus, where it is associated with other senses. And then it is returned to the cortex in a richer, multisensory form that is constantly elaborated, reverberating into a symphony of life experiences.

The thalamus and cortex work dynamically by passing loops of information back and forth, Dr. Llinás said. “If you think of the brain as an orchestra, the thalamus is the conductor. The players are in the cortex. When the conductor makes a move, the players follow. The conductor then hears their sounds and makes new moves, resulting in a continuous dialogue.”

Cells in the thalamus and cortex rely on intrinsic electrical properties to keep the music going. “Groups of neurons, millions strong, act like little hearts beating all their own,” Dr. Llinás said. They can oscillate at multiple frequencies, depending on what is happening in the outside world.

When the brain is awake, neurons in the cortex and thalamus oscillate at the same high frequency, called gamma. “It’s like a Riverdance performance,” Dr. Llinás continued. “Some cells are tapping in harmony and some are silent, creating myriads of patterns that represent the properties of the external world. Cells with the same rhythm form circuits to bind information in time. Such coherent activity allows you to see and hear, to be alert and able to think.”

But at day’s end, cells in the thalamus naturally enter a low-frequency oscillation. They burst slowly instead of firing rapidly. With the thalamus thrumming at a slower rhythm, the cortex follows along. You fall asleep. Your brain is still tapping out slow rhythms, but consciousness is suspended.

Dr. Llinás believes that these disrupted rhythms can be set off by a variety of causes — faulty genes, brain injury, chemical imbalance. In the case of his colleague Dr. Kelly, a small portion of the auditory cortex was damaged by helicopter noise. Dr. Llinás spotted it in the MEG machine — a spot oscillating as if in light sleep.

Tinnitus and other dysrhythmias can be treated with deep brain stimulation, drugs or tiny surgical lesions that return brain oscillations to normal, he said. The goal is to wake up parts of the brain that have fallen into low-frequency sleep mode.

THE NEW YORK TIMES, SCIENTISTS AT WORK, DECEMBER 1 2008