Aufklärung ist der Ausgang des Menschen aus seiner selbstverschuldeten Unmündigkeit. Unmündigkeit ist das Unvermögen, sich seines Verstandes ohne Leitung eines anderen zu bedienen. Selbstverschuldet ist diese Unmündigkeit, wenn die Ursache derselben nicht am Mangel des Verstandes, sondern der Entschließung und des Mutes liegt, sich seiner ohne Leitung eines andern zu bedienen. Sapere aude! Habe Mut, dich deines eigenen Verstandes zu bedienen! ist also der Wahlspruch der Aufklärung.
-- Immanuel Kant --
Sunday, September 04, 2005
vidit
Artis monumentum, qui unum vidit,
nullum vidit,
qui mille vidit, unum vidit.
-- Eduard Gerhard --
nullum vidit,
qui mille vidit, unum vidit.
-- Eduard Gerhard --
Aufrichtig - Goethe
aufrichtig zu sein, kann ich versprechen, unparteiisch zu sein aber nicht
[posso prometer ser sincero, mas não imparcial]
-- Goethe --
[posso prometer ser sincero, mas não imparcial]
-- Goethe --
Monday, August 29, 2005
Endlichen - Goethe
Willst du ins Unendliche schreiten, geh nur im Endlichen nach allen Seiten.
--GOETHE--
--GOETHE--
The Inhibition of Simultaneous Stimuli - Békésy - Sensory Inhibition
When we look at a historical section of a sense organ with a large surface, we find nerve fibers going directly to the sensory ganglion, and in addition we find a large number of lateral fibers running parallel to the surface and connecting two or more end organs with one another. It was Held (1926) who showed that in the organ of Corti there are never fibers running from every hair cell more or less direclty to the modiolus of the cochlea, and also other fibers running perpendicular to these along the basilar membrane, often connecting the hair cells over nearly a half turn of the cochlea. Unfortunately these lateral connections often seem difficult to stain. (...) The lateral fibers of the cochlea are represented in Fig. 20. At present it is still uncertain to what extent these fibers are involved in the immediate process of hearing. (...) I am unable to understand how this retinal circuitry fails to produce constant oscillation. It is difficult to imagine what type of reduction of feedback is used to avoid this oscillation. Even a simples feedback system requires many precautions to prevent its going into oscillation and to cause it to return to its original equilibrium condition after a stimulus has ceased to act upon it.
Figure 20
Figure 23
For present purposes, a simple scheme is sufficient to illustrate the problem. The small dots near the bottom of Fig. 23 represent a system of receptors on the surface of the skin. The variations of a stimulus are indicated by the lowermost graph with a maximum in the middle. There are lateral connections between the receptors and nerve fibers that run upward to the first-order ganglion cells in a row a. Alongside each of these nerve fibers is a representation of its pulse rate: the number of spikes for a certain unit of time is shown. Adrian in 1928 found that the discharge rate of a sensory nerve fiber increases with the magnitude of the stimulus acting on its end organ. In the two fibers on the far left and right sides the stimulation is minimal and the discharges represent spontaneous activity. Toward the middle the stimulus intensity increases and so also does the discharge rate.
From the first layer of ganglion cells we go to a similar level above, shown at b, and from there to still higher level, c. As far as we can now discover, the result of the lateral interconnections is to reduce or "funnel" the laterally spreading stimulation to a progressively localized section of the neural pathway, as indicated by the sketch of the sensation at the top of the figure.
This simple scheme immediately brings up the question of the kind of frequency sensation that will be produced by a stimulus whose amplitude tapers away from a central maximum as shown in this figure. It is apparent that the lateral inhibition that occurs in sense organs is not the straightforward kind that we find in muscle systems. The lateral inhibition of sense organs is actually a funneling action that inhibits the smaller stimulus effects and collects the stronger effects into a common pathway.
(...)
In a crude way we can distinguish four types of inhibitory pathways, as illustrated in Fig. 24. As A is shown the simple form of lateral inhibition that has just been described. At B is shown a forward type of inhibition, at C a backward type, and at D a form of central inhibition. In human sense organs there is an interplay of all these types of interaction.
Figure 24
The question arises whether inhibition is the correct term for this whole series of phenomena. With our limited knowledge of inhibition phenomena in single neural pathways it is difficult to decide on the proper category. In addition to inhibition we might consider the term "sensory distortion", or even "disinhibition" - because it may happen that normally the neural pathways are blocked, and the effect of a stimulus is to remove the blockage. I prefer to call the effect "funneling", because even for central inhibition there is usually an increase in the magnitude of the sensation referred to certain places.
Figure 20
Figure 23
For present purposes, a simple scheme is sufficient to illustrate the problem. The small dots near the bottom of Fig. 23 represent a system of receptors on the surface of the skin. The variations of a stimulus are indicated by the lowermost graph with a maximum in the middle. There are lateral connections between the receptors and nerve fibers that run upward to the first-order ganglion cells in a row a. Alongside each of these nerve fibers is a representation of its pulse rate: the number of spikes for a certain unit of time is shown. Adrian in 1928 found that the discharge rate of a sensory nerve fiber increases with the magnitude of the stimulus acting on its end organ. In the two fibers on the far left and right sides the stimulation is minimal and the discharges represent spontaneous activity. Toward the middle the stimulus intensity increases and so also does the discharge rate.
From the first layer of ganglion cells we go to a similar level above, shown at b, and from there to still higher level, c. As far as we can now discover, the result of the lateral interconnections is to reduce or "funnel" the laterally spreading stimulation to a progressively localized section of the neural pathway, as indicated by the sketch of the sensation at the top of the figure.
This simple scheme immediately brings up the question of the kind of frequency sensation that will be produced by a stimulus whose amplitude tapers away from a central maximum as shown in this figure. It is apparent that the lateral inhibition that occurs in sense organs is not the straightforward kind that we find in muscle systems. The lateral inhibition of sense organs is actually a funneling action that inhibits the smaller stimulus effects and collects the stronger effects into a common pathway.
(...)
In a crude way we can distinguish four types of inhibitory pathways, as illustrated in Fig. 24. As A is shown the simple form of lateral inhibition that has just been described. At B is shown a forward type of inhibition, at C a backward type, and at D a form of central inhibition. In human sense organs there is an interplay of all these types of interaction.
Figure 24
The question arises whether inhibition is the correct term for this whole series of phenomena. With our limited knowledge of inhibition phenomena in single neural pathways it is difficult to decide on the proper category. In addition to inhibition we might consider the term "sensory distortion", or even "disinhibition" - because it may happen that normally the neural pathways are blocked, and the effect of a stimulus is to remove the blockage. I prefer to call the effect "funneling", because even for central inhibition there is usually an increase in the magnitude of the sensation referred to certain places.
Adaptation and Inhibition as a Means of Suppressing an Excess of Information - Békéy - Sensory Inhibition
There are many ways in which a physical activity may be so modified as to cause a human observer's perception of it to depart widely from the indications of physical apparatus. We are all aware of the existence of sensory threshold, adaptation process, and nonlinearity, all of which represent departures of perception from the regular variations of magnitude in a physical stimulus.
A further process is inhibition, whose effects are equally unexpected and often even more profound than these objects.
(...)
The important thing in a communication network is not the output level attained but the signal-to-noise ratio, for it is the ratio that determines our ability to recognize the signal a distinct from the noise. In the nervous system also it was found that "noise" is always present, in the form of general background of spontaneous activity, and a sensory effect has to be identified in the presence of this background (Hoagland, 1932). This problem is still with us.
(...)
A decade ago there was a development of communications and information theory. Already we have too much of this theory, and it is necessary to develop an inhibition theory. We shall need to discover a way of measuring the loss of information caused by a given amount of inhibition. A possible measure is the number of bits lost when the information is passed through a system divided by the number of bits introduced at the input. Such a measure I consider more important in physiology and psychology than in communications engineering.
We know that any information that we have at hand contains a number of small disturbances. These are usually eliminated by a statistical treatment. The mean value of a series of measures represents the inhibition of many small unwanted bits of information, but this procedure does not go far enough. What we are interested in is direct from of inhibition that cancels out a whole of unwanted information. The problem is of far greater scope than statisticians have ever dreamed of.
The simplest way to get rid of information is to reduce the sensitivity of the receptors. This method s used effectively in all complex living systems. For example, we know that the organ or Corti of the ear is sensitive to displacement. This sensitivity is so great that one can almost hear the Brownian movements of molecules. (...) the organ of Corti, as living tissue, requires a constant blood supply (...) hence we should expect to hear our own heartbeat with tremendous loudness. We do not so because, for one thing, there is a factor of frequency differentiating between external sound stimuli and the sound of the heartbeat. The circulatory pulsations are of low frequency, and the solution that nature made to the problem was to reduce the sensitivity of the ear to lower frequencies while leaving the sensitivity unimpaired in the range between 1000 and 4000 cycles per second (cps).
Thus it is not surprising to find that the threshold sensitivity for frequencies around 20 cps is nearly 10,000 times less than for frequencies around 1000cps. These relations may be seen in Fig.3.
Figure 3
(...)
Adaptation is a common process in living systems for the reduction of the effect of a stimulus. It is seen mainly as a progressive loss of sensitivity during a period of stimulation.
(...)
The retina seems to lose its "pattern recognition ability" quickly if the pattern is maintained on one portion of its surface. As has been proved by Riggs and others (1953) an image that is made stationary on the retina disappears partly or completely in a few seconds.
(...)
That the transients of a stimulus are of utmost importance in vision was shown in an objective way in experiments on the eye of the horseshoe crab, Limulus, by Ratliff, Hartline, and Miller (1963). Even a moderate change in the stimulus intensity, such as doubling or halving, produced an immediate change in the discharge rate of a single unit of the optic nerve, as seen in Fig. 10. This figure shows the effect of a doubling of the light stimulus, and then a return of the stimulus to its former level. The response frequency increases rapidly to more than twice its original value when the light is increased, and in about 0.5 sec returns to the base line. Then when the light intensity is dropped to its initial level, the frequency falls abruptly and soon rises to the base level once more.
Figure 10
A further process is inhibition, whose effects are equally unexpected and often even more profound than these objects.
(...)
The important thing in a communication network is not the output level attained but the signal-to-noise ratio, for it is the ratio that determines our ability to recognize the signal a distinct from the noise. In the nervous system also it was found that "noise" is always present, in the form of general background of spontaneous activity, and a sensory effect has to be identified in the presence of this background (Hoagland, 1932). This problem is still with us.
(...)
A decade ago there was a development of communications and information theory. Already we have too much of this theory, and it is necessary to develop an inhibition theory. We shall need to discover a way of measuring the loss of information caused by a given amount of inhibition. A possible measure is the number of bits lost when the information is passed through a system divided by the number of bits introduced at the input. Such a measure I consider more important in physiology and psychology than in communications engineering.
We know that any information that we have at hand contains a number of small disturbances. These are usually eliminated by a statistical treatment. The mean value of a series of measures represents the inhibition of many small unwanted bits of information, but this procedure does not go far enough. What we are interested in is direct from of inhibition that cancels out a whole of unwanted information. The problem is of far greater scope than statisticians have ever dreamed of.
The simplest way to get rid of information is to reduce the sensitivity of the receptors. This method s used effectively in all complex living systems. For example, we know that the organ or Corti of the ear is sensitive to displacement. This sensitivity is so great that one can almost hear the Brownian movements of molecules. (...) the organ of Corti, as living tissue, requires a constant blood supply (...) hence we should expect to hear our own heartbeat with tremendous loudness. We do not so because, for one thing, there is a factor of frequency differentiating between external sound stimuli and the sound of the heartbeat. The circulatory pulsations are of low frequency, and the solution that nature made to the problem was to reduce the sensitivity of the ear to lower frequencies while leaving the sensitivity unimpaired in the range between 1000 and 4000 cycles per second (cps).
Thus it is not surprising to find that the threshold sensitivity for frequencies around 20 cps is nearly 10,000 times less than for frequencies around 1000cps. These relations may be seen in Fig.3.
Figure 3
(...)
Adaptation is a common process in living systems for the reduction of the effect of a stimulus. It is seen mainly as a progressive loss of sensitivity during a period of stimulation.
(...)
The retina seems to lose its "pattern recognition ability" quickly if the pattern is maintained on one portion of its surface. As has been proved by Riggs and others (1953) an image that is made stationary on the retina disappears partly or completely in a few seconds.
(...)
That the transients of a stimulus are of utmost importance in vision was shown in an objective way in experiments on the eye of the horseshoe crab, Limulus, by Ratliff, Hartline, and Miller (1963). Even a moderate change in the stimulus intensity, such as doubling or halving, produced an immediate change in the discharge rate of a single unit of the optic nerve, as seen in Fig. 10. This figure shows the effect of a doubling of the light stimulus, and then a return of the stimulus to its former level. The response frequency increases rapidly to more than twice its original value when the light is increased, and in about 0.5 sec returns to the base line. Then when the light intensity is dropped to its initial level, the frequency falls abruptly and soon rises to the base level once more.
Figure 10
Wednesday, July 27, 2005
Monday, July 25, 2005
Perception
Since the most ancient days mankind has been intrigued by the way human beings perceive the world surrounding them. That's through our sensitive mechanisms that we feel the world and makes us aware of our own existence. Aristotle made an attempt to explain all the perceptions mechanisms (seeing, hearing, touching, smelling and tasting) in his work "De Anima". He explained all those senses rather in purely physiological terms.
According to Aristotle the objects of senses might be divided into the following groups: the special (such as color which is the special object of sight, and sound of hearing), the common, or apprehended by several senses in combination (such as motion or figure), or the incidental or inferential (from immediate sensation of white we know the object we see is white). Among the five special senses, touch is the must rudimentary, hearing the most instructive, and sight the most ennobling. The organs of those senses never act directly, but rather through some sort of medium such as air. Even touch, which seems to act by direct contact, probably involves some vehicle of communication.
Aristotle believed the head to be the central organ of all senses. It recognizes the common qualities which are involved in all particular objects of sensation. At first there is a sense which brings us a consciousness of sensation, and then, in an act before the mind, it holds up the objects of our knowledge and enables us to distinguish and gather the different information reported by different senses.
The word Perception has its origin in the Latin language, it comes from the addition of the prefix 'per' to 'conceptum'. 'Conceptum' is the Latin word for concept, what is something conceived in mind, a mental image. The addiction of the prefix 'per' brings the meaning of through or complete. That's makes perception, a complete mental image, something conceived in our mind through our sensitive organs. From this statement we may infer that only animals provided with sensitive organs or human beings are able of something like perception.
According to Aristotle the objects of senses might be divided into the following groups: the special (such as color which is the special object of sight, and sound of hearing), the common, or apprehended by several senses in combination (such as motion or figure), or the incidental or inferential (from immediate sensation of white we know the object we see is white). Among the five special senses, touch is the must rudimentary, hearing the most instructive, and sight the most ennobling. The organs of those senses never act directly, but rather through some sort of medium such as air. Even touch, which seems to act by direct contact, probably involves some vehicle of communication.
Aristotle believed the head to be the central organ of all senses. It recognizes the common qualities which are involved in all particular objects of sensation. At first there is a sense which brings us a consciousness of sensation, and then, in an act before the mind, it holds up the objects of our knowledge and enables us to distinguish and gather the different information reported by different senses.
The word Perception has its origin in the Latin language, it comes from the addition of the prefix 'per' to 'conceptum'. 'Conceptum' is the Latin word for concept, what is something conceived in mind, a mental image. The addiction of the prefix 'per' brings the meaning of through or complete. That's makes perception, a complete mental image, something conceived in our mind through our sensitive organs. From this statement we may infer that only animals provided with sensitive organs or human beings are able of something like perception.
Sunday, June 19, 2005
a little about Hans Christian Andersen
Hans Christian Andersen was born in Odense, Denmark, on April 2, 1805, so that's makes 2005 it's 200th birthday anniversary.
Still as a child Andersen showed great imagination, he built himself a little toy-theatre and sat at home making clothes for his puppets, and reading all the plays that he could borrow; among them were those of Ludvig Holberg and William Shakespeare. Andersen, throughout his childhood, had a passionate love for literature. He was known to memorize entire Shakespeare plays and recite them using his wooden dolls as the characters.
At age 14, Andersen moved to Copenhagen to look for work in show business. He had a pleasant soprano voice and succeeded in getting into the Royal Danish Theatre but had to leave when his voice changed.
King Frederick VI became interested in the strange boy after a chance meeting and sent him for some years, free of charge, to the grammar-school at Slagelse. Before he started for school, Andersen published his first volume, The Ghost at Palnatoke's Grave (1822).
Some hold that his works express the sorrow of being different. One of the most telling stories in that respect is the tale of the Little Mermaid, who takes her own life since she cannot be loved by her beautiful prince. It is thought to exemplify his love for the young Edward Collin, to whom he wrote: "I languish for you as for a pretty Calabrian wench . . . my sentiments for you are those of a woman. The femininity of my nature and our friendship must remain a mystery." Collin, who was not erotically attracted to men, wrote in his own Memoirs: "I found myself unable to respond to this love", and this caused the author much suffering. Likewise, the infatuations of the author for the Danish dancer Harlod Scharf and the young duke of Weimar probably remained on a Platonic level. Andersen's private journal records his refusal to have sexual relations with either men or women and his release through masturbation. Today he would have been considered asexual.
In the spring of 1872, Andersen fell out of bed and severely hurt himself. He was never again quite well, but he lived until the August 4, 1875, when he died very peacefully in the house called Rolighed, near Copenhagen. He is buried in the Assistens Cemetery, in Copenhagen, Denmark.
His best-known fairy tales include:
* The Angel
* The Bell
* The Emperor's New Clothes
* The Emperor's Nightingale
* The Fir Tree
* The Little Match Girl
* The Little Mermaid
* The Real Princess
* Red Shoes
* The Snow Queen
* The Steadfast Tin Soldier
* The Swineherd
* Thumbelina
* The Ugly Duckling
* The Old House
* The Happy Family
* The Story of a Mother
* The Shadow
* The Dream of Little Tuk
* Wild Swans
The Steadfast Tin Soldier
"I cannot bear it!" said the pewter soldier. "I have shed pewter tears! It is too melancholy! Rather let me go to the wars and lose arms and legs! It would at least be a change. I cannot bear it longer! Now, I know what it is to have a visit from one's old thoughts, with what they may bring with them! I have had a visit from mine, and you may be sure it is no pleasant thing in the end; I was at last about to jump down from the drawers."
--Hans Christian Andersen--
Life's Melody
Life is like a beautiful melody, only the lyrics are messed up.
--Hans Christian Andersen--
--Hans Christian Andersen--
Thursday, June 16, 2005
Wednesday, June 01, 2005
madness
I can calculate the motion of heavenly bodies but not the madness of people.
-- Isaac Newton --
-- Isaac Newton --
Saturday, May 21, 2005
multitudes
Do I contradict myself? Very well, then I contradict myself, I am large, I contain multitudes.
-- Walt Whitman --
-- Walt Whitman --
Friday, April 29, 2005
Being With You (In Paris)
In the music Being With You (In Paris) from Steve Vai there's a poem he declaims during the show. It was in French and it was translated by a fan called John Pusztai. I could not find the poem in the internet... so I asked a friend of mine to transcribe it... and the another to translate into portuguese... and finally I did translate it into english! Bellow follow the result.
"Je n'oublierai jamais ces jours merveilleux qui sont si clairs dans mon coeur et ma mémoire. Les choses simples semblent si profondes. Puis il y a cette photo, le soleil brille au dessus de la Seine, et le ciel rempli de couleurs que des artistes ont tenté de capturer pendant des siècles. Tu es debout sur le pont, la tour Eiffel à ta gauche faisait figure d'un vieille ami parlant des amoureux avec lesquels elle a posé dans le passe. Cette ville appelle le respect. Elle a pris au fil du temps avec ses victoires. La richesse de son art et de sa culture sentit dans les huiles heureuses... Pendant que nous mémorisons les bruits et les saveurs des rues piétonnes. Et si nous ne pouvons plus nous voir et nous embrasser dans la magie de cette ville, la mélodie ne changera jamais et me rappellera toujours pareil avec toi."
"I will never forget those wonderful days which are still so bright in my heart and memory. The simplest things seems so deep... and then there is this photo. The Sun shines over the Sena and the sky, full of colors, which the artists try go catch over the centuries. You're standing on the bridge, the Eiffel tower is on your left playing an old friend character, talking about loves gone on steps. This city claims for respect. It claims time line with its victories. Its fortune held in its arts and culture laid on those happy oils... While we memorize the noise and flavor of the picturesque streets. And I can not see ourselves and embrace ourselves under the magic of this city. The melody will always sound the same, and it will always make me remember you."
"Je n'oublierai jamais ces jours merveilleux qui sont si clairs dans mon coeur et ma mémoire. Les choses simples semblent si profondes. Puis il y a cette photo, le soleil brille au dessus de la Seine, et le ciel rempli de couleurs que des artistes ont tenté de capturer pendant des siècles. Tu es debout sur le pont, la tour Eiffel à ta gauche faisait figure d'un vieille ami parlant des amoureux avec lesquels elle a posé dans le passe. Cette ville appelle le respect. Elle a pris au fil du temps avec ses victoires. La richesse de son art et de sa culture sentit dans les huiles heureuses... Pendant que nous mémorisons les bruits et les saveurs des rues piétonnes. Et si nous ne pouvons plus nous voir et nous embrasser dans la magie de cette ville, la mélodie ne changera jamais et me rappellera toujours pareil avec toi."
"I will never forget those wonderful days which are still so bright in my heart and memory. The simplest things seems so deep... and then there is this photo. The Sun shines over the Sena and the sky, full of colors, which the artists try go catch over the centuries. You're standing on the bridge, the Eiffel tower is on your left playing an old friend character, talking about loves gone on steps. This city claims for respect. It claims time line with its victories. Its fortune held in its arts and culture laid on those happy oils... While we memorize the noise and flavor of the picturesque streets. And I can not see ourselves and embrace ourselves under the magic of this city. The melody will always sound the same, and it will always make me remember you."
Sunday, April 17, 2005
Eternal Sunshine
[Mary reads to Dr. Mierzwiak out of "Bartlett's Familiar Quotations"; the lines are from Alexander Pope's poem "Eloisa to Abelard"]
Mary: How happy is the blameless Vestal's lot! / The world forgetting, by the world forgot / Eternal sunshine of the spotless mind! / Each pray'r accepted, and each wish resign'd.
Mary: How happy is the blameless Vestal's lot! / The world forgetting, by the world forgot / Eternal sunshine of the spotless mind! / Each pray'r accepted, and each wish resign'd.
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