The simple "brains" of flatworms have recently been causing some excitement among scientists. These worms are approximately one inch long, are mud-brown in color, and live quietly on the underside of rocks in fresh water strems. They have no system of veins through which blood flows; they have a stomach with only one opening, and a head that controls the rest of their bodies.
Flatworms can grow a new front end when the old one is cut away. You could cut a flatworm into two parts and in a few weeks have two new worms. The old tail would grow a new head , and the old head would grow a new tail. The worms' ability to make new parts grow is not what caused excitement among the scientists who are studying them. Such growth is a form of regeneration -a very similar process is performed by ordinary earthworms, starfish, and many others animals. What is surprising is that flatworms can learn and their learning can be transferred to other flatworms in a strange manner! The educated flatworms are the ones which may help us better to understand the function of the human brain.
Picture in your mind a long container filled with water. At both ends are electrodes. Over the container are two lights. Into the container goes a flatworm, the lights flash, and an electric shoc runs through the water. The light does not cause the electric shock; it is the signal that a shock is coming. The shock causes the worm to contract. After approximately 300 times, the flatworm is educated. It has learned what the flash of light means, and it contracts as soon as the light flashes, even though no electric shock may follow.
Suppose scientists cut off the "brain" of an educated worm and allowed a new head to grow onto the tail. Would the worm have to begin again to learn that shock follows a light flash? Was all of the learning concentrated in the front end, or might some be present in the back part of the nervous system which continues into the tail end? Scientistis experimented with front and tail ends of educated worms and found, to their surprise, that the tail end retained as much of the lesson as the head, wherethe simple "brain" of central nerve ends is located. Not so surprising was the fact that the head end, wen allowed to grow a new tail and placed in the container of water, reacted as it had before. It retained the learned reaction.
Suppose a flatworms is cut in two and the head learns to react to the light. After the head end grows a new tail, it is cut in two. The tail end grows a new head, and the head end grows a new tail. What happens when these worms are tested? The worm which has grown from the original head end retains some of the matter which was part of the "brain" that was educated. The tail end which grew a new head is made of entirely new matter. Both parts learned faster than an uneducated worm, indicating that some sort of learning occured that was transferred when the worm grew a new tail or head.
One American scientist has suggested that the behavior of the flatworms may help other scientists better understand what memory is and how learning occurs. If the studies could be applied to men as well as to worms, it might be possible in the distant future for men to aid their memory with chemicals. each bit of knowledge shines a little more light on the strange actions of the nervous system.
American scientists have done other experiments that are interesting. Uneducated flatworms were fed bits of educated flatworms. When these worms were put in the container of water, they contracted at the light flashes in a much shorter period of time than worms which had not eaten ay educated worms. They reacted twice as fast.
It is known that a flatworm does not digest food in the same manner that humans do. It swallows large bits of food in such a manner that whole cells are probably undisturbed. Perhaps large molecules which store learning or memory, "educate" the uneducated flatworms which eats them. The human digestive system breaks up cells and large molecules, changing them into entirely new kinds of molecules.
TLDR: El flatworm tiene una gran capacidad de regeneración, pudiendo regenerar el cuerpo completo a partir de una pequeña porción (unos cientificos, al ensañarse con uno en particular, lograron conseguir más de 20000 ejemplares idénticos). En este caso al gusano le 'enseñaban' un estimulo respuesta: luz implica electroshock. Luego lo dividían dejando que naciera un gusano con cabeza antigua y nueva cola y otro con nueva cabeza y cola antigua. 'Sorprendentemente' el gusano crecido desde la cola también recordaba el entrenamiento. Más sorprendente: Gusano 'educado' cortado en mitad, a la cabeza le crece cola nueva, se vuelve a dividir y a la nueva cola le crece una nueva cabeza, es decir, se tiene un gusano totalmente nuevo y este aún conservaba parte del aprendizaje (era mas fácil entrenarlo). Y aún más: A gusanos no entrenados los alimentaron con pedazos de gusanos entrenados y se consiguió aprendizaje el doble de rápido comparado con gusanos no forzados al canibalismo.
** Cuando se habla de que un gusano recuerda no se refiere (o por lo menos yo no me refiero) a un recuerdo consciente. No es que el gusano 'sepa' o razone en la implicancia de luz -> electroshock, esto es a nivel químico.
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