De los ojos del Sapo a los nuestros, de circuitería a los pensamientos.

What is the bridge between nerve impulse and thought? This question has puzzled man for hundreds of years. How can chemically-caused changes which producce electricity in nerves mean anything to the human brain? What is the key that will unlock the code?
All messages to the brain are composed of paterns of dots. The timing of the nerve signals gives the meaning to the pattern. Each pause, or interval, has a importan function. Stimuli cause various rates of signaling, and the patterns which result have meaning for the brain.
Scientists are discovering the meaning of the code of some of the less complicated messages which travel through the nerve fibers of some animals used in expements. They "listen" to a message by putting electrodes into nerve fibers and then study the bursts of impulses. This is only one of the many methods by which man is exploring the problem of how nerve impulses become meaning.
Since approximately 100 million signals toward the brain of a human beign each second, the brain would be very confused if it did not sort them. Only certain patterns of dots receive attention. Only certain bursts of electrical impulse become meaning. For instance, a mother may sleep while the neighbors in the apartment above her have a noisy party. In spite of this noise, she is awakened by the slightest cry of her child.

//Creo que todos sabemos que los zancudos pueden ver el en infrarrojo y por tanto ver fuentes de sangre caliente. Eso es mas o menos fácil de aceptar pensando en que 'solamente' tienen la sensibilidad a las frecuencias electromagneticas corridas. Pero la visión del sapo es diferente en otro sentido...//

El sapo no ve lo que no le sirve

To learn more about the sorting of messages, scientists have made a study of the eyes of frogs. A frog sees only what it needs to see. Vague shapes, forms, and movements are sent to the brain in a relatively direct manner. Information which is not connected with obtaining food or avoiding an enemy is completely ignored. For instance, a frog is never aware of the fact that a fly has six legs. It does not even notice a fly that is traveling away from it. Nevertheless, it does notice moving objects that are the size and shape of insects or worms when they move toward it. Such animals could become dinner. A frog would starve among newly killed insects since they would not move.
A frog is quickly aware of large, dark objects. These could be enemies, so they are easily recognized as such. Unnecessary information is not allowed to enter. No report of it reaches the brain.
//Dentro de nuestro rango de visión (luz visible, frecuencia de muestreo aceptable, etc) ¿Nos perderemos de algunos fenómenos que fueron rechazados antes de ser analizados por ser demasiado complejos en sus formas o por ser innecesarios en nuestra supervivencia?//
Some American scientist used very small electrodes to study the eyes and brains of frogs. They recorded impulses in nerve fibers less than 1/25000 of an inch wide. They found four different kinds of fibers: The "bug" finders which react to curved, moving objects; the fubers which react to sharp edges; those which react to changing distributions of light; and those which react to a lessening of the amount of light, such as the shadow of another animal might cause. These four types of fibers were found to be associated with four different types of neurons. Here was evidence of a relationship between body parts and function, between the shapes of neurons and their duties.
...
//El pensamiento como epifenómeno de circuitería//
With the knowledge acquired from studies on the eyes of a frog and other experiments, engineers have designed devices that do some of the things that neurons do. A group of them developed an electrified brain model that pictures the birth of a thought. In this device, brain centers are represented by flat, round pieces of metal on which are many tiny electric lights. A system of moving lights and flashing images shows how the brain receives information. Electrically coded messages move along the model's nerve pathways. These cause patterns to appear on the large metal circles which represent the cortex of the brain. When the brain becomes conscious of an image, a figure appears on a large central screen. Sound, sight, and memory all join to produce a wide variety of patterns on the screen, finally resulting in judgment and action. So the birth of a thought is illustrated, but the solution to the code which the nerves send to the brains is still largely a mystery.
...
Certainly, after a person receives stimuli through his sense organs, electrical impulses carry messages to the brain with its many connecting pathways. What one perceives becomes experience, and experience is stored in memory, which furnishes the standard by wich to measure everything one does. Electrical impulses become meaning, and learning comes from experience.

(textos sacados de "The Miracle of your Mind")

The flatworm brain: Comiendo recuerdos.

En la biblioteca de Beauchef me encontré con el libro: 'The Miracle of Your Mind" de Margaret Hyde. Es pequeño y de rápida lectura. Es una especie de recopilación de la información en neurociencia de la época (libro publicado en 1970). Como no encontré versión online me daré el trabajo de pasar a computador alguno de los pasajes que me llamaron la atención. A continuación, lo que el libro habla sobre un gusano increíble y lo que se aprende de él.

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.

añadiendo..