Signaling

“ A simple (acyclic) social signal transduction pathway maps adverse social conditions onto activation of the conserved transcriptional response to adversity (CTRA) in leukocytes. Brain-mediated perceptions of social threat activate the sympathetic nervous system (SNS) , leading to release of norepinephrine (NE) at SNS nerve terminals, activation of β-adrenergic receptors on adjacent cells, and stimulation or repression of specific transcription factors in response to the cyclic 3′-5′ adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway. ”

“ These meanings usually include the letters of the alphabet and numerals, combinations of which being used to formulate necessary information. Combinations of elements of any system can also, however, be used to indicate any desired meaning.
With reference to period of visibility, signals are of two kinds, transient and permanent. A transient signal is one which disappears as soon as completed; [11] a permanent signal is one that remains in view for some time. Heliograph signals are transient signals, while signals made by code flags are permanent signals. ”

“ In most systems of signals suitable for military use, each signal is composed of one or more separate units, known as elements. Having prescribed a certain number of elements, the various signals are formed by having these elements appear singly or together in different arrangements or combinations. The continental system is one of two elements, namely the dot and the dash, while the Morse system employs three elements, the dot, the dash, and the space. Having agreed upon a certain number of combinations of elements, a system of signals is formed by giving a meaning to each combination. ”

“ Signals may be executed, first, exclusively by bodily action; second, by action of the person in connection with objects, such as a blanket, or a lance, or the direction imparted to a horse; third, by various devices, such as smoke, fire or dust, when the person of the signalist is not visible. When not simply intended to attract attention they are generally conventional, and while their study has not the same kind of importance as that of gesture signs, it possesses some peculiar interest. ”

“ If one likens each nerve cell to a central telephone office, each of its filamentous prolongations to a telephone wire, one can imagine a striking analogy between the modus operandi of nervous processes and of the telephone system. ”

“ N. B. Much practice is necessary to enable members to exchange this signal in such a manner as not to attract attention.
2d. The Signal of Danger—This signal is for use when Miss Jane, or any other foe-woman, heaves in sight. It consists in rubbing the nose violently, and at the same time giving three stamps on the floor with the left foot. It must be done with an air of unconsciousness.
3d. The Signal for Consultation.—This signal is for use when immediate communication is requisite between members of the Society. ”

“ But how did your eyes get the message to your brain, and how did your brain tell your legs to stop walking? We must have in our bodies a kind of telephone system. And that is, in fact, just what we have. Our brain is our “central office”; and our nerves are the wires, running from all parts of our body to the brain, carrying messages back and forth. ”

“ A change of the subordinate elements of the percept does not matter so much as the slightest modification in the quality or even in the intensity of the signal. This, of course, does not mean that the subordinate sensory elements are not psychologically and biologically of the utmost consequence to the organism, but they are not of that immediate importance as the focal, nuclear elements appear to the consciousness of the organism. The nuclear elements, as signal, focus the interest of the animal. ”

“ The signal experiment is duplicated thousands of times in the education of every human being. He learns the meaning of signs and slight indications; that is, he learns to recognize important facts by aid of signs that are of themselves unimportant. We shall have much to say on this matter in a later chapter on perception. Man learns signs more readily than such an animal as the rat, in part because the human being is naturally more responsive to visual and auditory stimuli. Yet the human being often has trouble in learning to read the signs aright. ”

“ As in an imperfectly organised telephone service after many a repeated stimuli or “rings” the messages begin to reach their destinations, and as by practice the operators better and better learn their business, so the impulses passing through receptors and nerve-fibrils become organized into more or less efficient systems of arcs, and response is secured to them by some effector of gland or muscle. It is not true of man alone that practice makes perfect. ”

“ The brain is not so much the President of our Cell Republic as a great central telephone exchange, where messages from all over the body are received, sifted, and transmitted in more or less modified form, to other parts of the body. Three-fourths of the work of the brain consists in acting as "middle-man," or transmitter, of messages from one part of the body to another. ”

“ They connect all parts of the body one with another. Think of the whole telephone system of Britain linked up together with millions of receivers, thousands of local exchanges, hundreds of central exchanges, etc., the nervous system with its sense organs, sensory nerves, lower and higher nerve centres and motor nerves, is infinitely more intricate than that. ”

“ An external agent, say light, causes certain excitatory change in the tissue, and we refer to the agent which induces it, as the stimulus. Thus in the instance cited above, light is the stimulus, and it is the stimulus-effect that is transmitted to a distance. But in physiological literature no distinction is made between the stimulus and its effect, hence arises frequent use of the phrase 'transmission of stimulus'. It is obvious that it is not light but its effect that is transmitted. ”

“ Macpherson. "Let the safety signal be of one uniform shape, and small; let the red, or danger signal, be of as different a shape as can be made, and large; so different that it could never fail to catch the eye. For, look you, a head deficient in the organ of colour will usually have that of form very much developed: and if a driver could not see the light, he might the form: and so save his train." ”

“ When the circuit is closed there is a bubbling, murmurous sound in the ears, a warm sensation where the wires touch the cranium, and a feeling as of a motion through the brain, entering at one point and going out at another. ”

“ Each incoming stimulus carves out for itself in the central nervous system or deepens a pre-existing channel in the central nervous system, but channel is not a trough formed by the physical displacement of particles, it is a chemical channel, a thread or trace of the autocatalyst of central nervous activities, a thread which need not necessarily be supposed to be more than a few times the diameter of 'the sphere of molecular influence' in width. ”

“ We have now presented some evidence that nervous energy is discharged by the adequate stimulation of one or more of the various receptors that have been developed in the course of evolution. In response to an adequate stimulus, the nervous system is integrated for a specific purpose by the stimulated receptor, and but one stimulus at a time has possession of the final common path— the nerve mechanisms for action. The most numerous receptors are those for harmful contact; these are the nociceptors. ”

“ The arrangement of the nervous system is very much like that of a city telephone system. The sensory nerve cells all lead into a part of the nervous system to which is given the name of the Central Nervous System, just as the telephone wires all lead into a “central exchange.” ”

“ It precludes one receptor from occupying for long periods an effector organ to the exclusion of all other receptors. It prevents long continuous possession of a common path by any one reflex of considerable intensity. It favours the receptors taking turn about. It helps to ensure serial variety of reaction. The organism, to be successful in a million-sided environment, must in its reaction be many sided. ”

“ If danger to yourself, and you need assistance, you hold up the signal and let the smoke ascend, at short intervals. If you wish some one to approach you move it backwards. If you wish only to signal your own approach you move it forward, and so on through a long list of signs. ”

“ If we had been accustomed to do one kind of work for which we had a suitable implement, and it became suddenly necessary to do some other for which we had none, it would be natural for us to catch up the one we had and make a shift with that. If a swim-bladder can be worked in as a lung, or a pair of legs as part of a mouth, then why not a hunger-signal as a love-signal? ”

“ The reacter awaits the signal and reacts if it is of one sort, but omits to act if it is of another sort. The reaction thus occurs after discrimination; the motor impulse cannot be sent to the hand until the subject knows what the signal is. The nervous impulse, as Mr. Cattell says, must probably travel to the cortex and excite changes there, causing in consciousness the perception of the signal. ”

“ The same holds true of a whole psycho-physiological system,―there is a threshold of sensitivity below which the minimal stimulus cannot fall, the latter does not awaken any reaction in the system. All the senses reveal the presence of such thresholds which are also present in the case of all the higher psycho-physiological systems. If we term the stimulus which can just bring about a reaction in the system the stimulus threshold, we can say that a given system can only be thrown into activity by a stimulus rising in intensity above the stimulus threshold. ”

“ Do what we will, we shall never be born with a microscope at the eyes, and a telephone at the ears. Progress of this kind is not transmissible; only physiological acquisitions are transmissible. The sensibility of the nervous system of mediums is a progress on our relative obtuseness ”

“ The action of stimulus on living substances is usually detected by two different methods. In the case of motile organs, stimulus causes a change of form. Mechanical response may thus be obtained in a contractile tissue such as a muscle. But in others, nerve for example, stimulus causes no visible change; the excitation of the tissue may, however, be detected by characteristic electromotive changes. The advantage of the electric mode of detection of response is its universal applicability. ”

“ The form of the response curve, stimulus remaining constant, is modified by the molecular condition of the wire. A wire in a sluggish condition shows feeble response, the recovery being also slow. The same wire after it has been vibrated for a time exhibits a stronger response. Longer time is required for recovery from the action of a stronger stimulus. ”

“ We know that feelings ‘express’ themselves in various ways; we blush for shame and pale from fear; we shake with rage, and our ‘heart beats high’ with hope. Now it is possible to measure all these organic changes; to record the rate and height of pulse, for instance, or the variation in the volume of a limb according as blood flows into it or is withdrawn from it; physiology puts the necessary instruments at our disposal. The observer may therefore be harnessed to some such system of recording apparatus, and may be subjected to some pleasant or unpleasant stimulus ”

“ A second consequence is that each receptor being dependent for final communication with its effector organ upon a path not exclusively its own but common to it with certain other receptors, such nexus necessitates successive and not simultaneous use of the common path by various receptors using it to different or opposed effect. When two receptors are stimulated simultaneously, each of the receptors tending to evoke reflex action that for its end-effect employs the same final common path but employs it in a different way from the other, one reflex appears without the other. ”

“ Every stimulus which reaches a cell will take the line of least resistance, and this will be set out for it along those nerve-tracks which it has already traversed. Thus a definite path is formed for the course of a stimulus-wave, a customary line of march; it is always the same nerve-cells which exchange mutually their stimulus-waves. Presentation always awakens the same resulting presentations, and always appears in consciousness accompanied by them. This procedure is called the association of ideas. ”

“ By multiplying the combinations of signals a great variety of messages might be transmitted in this manner; but, to avoid mistakes, the signals should be written down and copies furnished the commander of each separate party, and they need not necessarily be made known to the other persons. During the day an intelligent man should be detailed to keep a vigilant look-out in all directions for smokes, and he should be furnished with a watch, pencil, and paper, to make a record of the signals, with their number, and the time of the intervals between them. ”

“ In perceptual two-choice decision making experiments one studies how sensory information influences response behavior. In each trial the experimental subject is presented with a stimulus and must use the information thus provided to choose one of two possible responses. The response behavior in these tasks, as defined by reaction times and performance, has been studied for over a hundred years [1] – [2] leading to a wealth of data and modeling results [3] . ”

“ We have seen that the wave of molecular disturbance in a living animal tissue under stimulus is accompanied by a wave of electrical disturbance; that in certain types of tissue the stimulated is relatively positive to the less disturbed, while in others it is the reverse; that it is essential to the obtaining of electric response to have the contacts leading to the galvanometer unequally affected by excitation ”

“ The reflex, as ordinarily understood, begins with the activity of a sense organ or receptor, from which a sensory impulse passes to the central nervous system or adjustor, whence the nervous disturbance makes its way to the third element or effector, usually a muscle. The sense organs or receptors are, for the most part, the distal ends of sensory neurones. ”