(Please give me good advice and comment)
Abstract：It has long been known that the body sensations are important for forming an emotion（in this paper, the term emotion is used only means emotional feeling ). But people have also seen that they are obviously not the all mental components of emotion. The ideas that emotions are a complex feeling consisting of different kinds of mental entities, and that simple affect as a important quality of all kinds of emotions and sensory feelings, they have appeared in scholars' works. Based on these ideas and synthesis the existing research findings on emotion, this paper proposes two hypotheses: (1) emotion and sensory feeling are the complex feeling consisting of the two detachable mental properties of affect and sensation（cognitive);（2）the affect in emotions may be the conditioned response of the affect in sensory feelings. And think that it is the essence of emotion to the affect that has only two mental properties of pleasure or displeasure and accompany with the mental state of like ro dislike that the same as a component in sensory feelings, the sensations from body and external objects provide distinctive features for various emotions. And has discussed the following questions: (1) The difference between affect and sensation, and their functions in emotion and sensory feeling.（2) Affect objectified as a widespread and important psychologic mechanism for emotion and sensory feeling (i.e., in specific emotions and sensory feelings, because of the combinations of affect and sensation, it turn the mental state of like ro dislike in the affect into the like ro dislike for sensations, thus appear our like ro dislike for the objectsof sensations from body or outside）. (3) The acquired mechanism of emotional body changes.
1. A hypothesis: emotions consist of affect and cognitive sensation
James thought that emotions are the sensations of body changes such as heart beats fast，muscular tension. But people further see that it might appear that we have these sensations without emotions （as when we play sports ) and we do not necessarily have these sensations when we have the emotions such as respect, adore. This shows that the body sensations are neither sufficient nor common for emotions, their meaning may be only provides a distinctive feature for the distinction between different kinds of emotions.
When talking about the distinctions between cognition and emotion，James said: " Without the bodily states following on the perception, the latter would be purely cognitive in form, pale, colourless, destitute of emotional warmth.1" However, looking at the there are not the nature of emotion in the perceptions of body changes when we play sports，the perception of body state is also purely cognitive in form，pale and destitute of emotional warmth when it is missing something. Although it is rare to the explanation of the difference in perceiving forms between cognition and emotion，the simple description for their basic characteristic may be as follows：The cognitive perceiving form, its basis is the various special sensations. Each sensation has a special receptors, a special neural pathway and a special cortical region. The sensations which compliant with the above conditions include color，brightness，sound，pressure，temperature site (include the site of a body part), the movement states of internal organs (such as a rise in heart-beats，the peristalsis in stomach，breathing rhythms)，muscular tension or relax, and other mechanical sensations of body such as picotement，formication and so on. Certainly，there is hardly any the circumstance that we perceive the external objects or our body by single sensation, the complex perception is the actual mental unit，and it has also integrating the images of memory and imagination in the unit. So what usually called sensation also refer to perception. The emotions, it is generally considered that they arise from some neural structure in limbic system in the core place of brain，and they have no special receptors and special neural pathway，and their projections of cortex are diffuse. Then, either from the view of phenomenon or classify them according to the elementary knowledge of their neural basis，all those James'“perceptions”of internal organs，muscles and so on are belong to the non-emotion and cognitive sensations. Although the sensations of body are indeed necessary for some emotions, or they are “superposition” with other mental property (the concept of superposition borrow from Damasio,he has proposed that the whole feeling of emotion is formed by the body images and the others images of visual or auditory and so on in the form of assembling be juxtaposition / superposition in the brain2)，as in the emotions of fear and anger，but they are not required for some others emotions,and may be replaced by the sensations of external objects, as in the emotions of interest, curiosity, respect and aesthetic feeling，that is,when we are concentrating on external objects,or when the emotions are not strong. And there is a lack of agreement between a sensation of body and its subjective natures (pleasant or unpleasant). For instance, the sensation of heartbeat, it can be either unpleasant (as when you are fear) or pleasant (as the so-called “I hear myself heartbeating, being with you” ). All these suggest that the sensations from body and external objects are important to various emotions，but they are neither sufficient nor pervasive. They can concomitancy with some emotions, and can also be separate from emotions and exist singly. Apparently, for emotion，besides those sensations there is also another more essential thing.
The research of “binding” problem suggested that perception is likely the whole mental image which is formed by the neural activities that occur in separate brain regions and integrate in time 3 . The emotion may be such "perception" which has integrated different kinds of neural patterns, and this integration may be spans the boundary between the sensation and another mental property which as the essence of emotion. In neural basis，this integration may be occur between cerebral cortex and some neural structures in limbic system. That is，so-called emotions may actually be the complex feelings consist of some sensations( from body or outside) and the mental property which has universality for all emotions through integration in time and space in different forms of assembling. For instance, the emotion of a typical fear,it may be consist of the cognitive sensations of the visual image of an object, muscle tension, heart beat fast, polypnea, and another non-cognitive mental property that exists in all emotions. For such universality mental property of emotions, we can use the term afect whose concept has more universality among related words. That is，all the emotions may be the complex feeling consist of of the two disparate mental properties of affect and sensation. The concepts of afect and emotion are consistent partially with Leventhal’s idea. He thinks that first of all the individual has an affect caused by external information,“the is just a simple negative or positive affect, rather than more complicated emotion that has a fine-classification. Then the feedbacks from expressive system and autonomic nervous system cause the production of emotion4 .” Moreover, such concept of affect is consistent with Johnston’s hedonic tone (pleasure or displeasure) that as a important component of all the feelings (include emotional feelings and sensory feelings) 5.
2. The objectification of affect: a important psychologic mechanism of emotion and sensory feeling
2.1. The sensation and affect in emotion; the phenomenon of affect objectified; motivation
The sensations in emotions，they should be those cognitive sensations or perceptions of body and external object that we can feel them in the states of emotion or non-emotion. The body sensations that often shows up in emotions include muscular tension, a rise in heart rate，polypnea（as fear and anger），temperature sensation within heart or stomach(as feel cold in heart when we are sadness; feel warm in heart when we are delight)，and some the movements of internal organs (as drastic gastrointestinal stirrings when we are despair) and so on. The sensations of external objects, it seems they are not so closely linked to emotion as the body sensations，but sometimes they are necessary to some emotions, such as the visual image of a object that makes us fear, the visual or auditory images in aesthetic feeling, and so on. All these basic sensations are base on the special receptors, special neural pathway and special cortical region. It has been found that the neurochemical bases are basically the same for all kinds of sensations, their specificity reflected in special cortical region. By different sensations, we can reflects the all kinds of distinctive features of body and external objects. These sensations themselves do not possess the attribute of emotion, and they can not only involve in emotions, but also occur alone. But they might have an important meaning for the distinctive feature between different kinds of emotions. The features in some emotions such as tension，relax and so-called “heart cold” ，they clearly come from sensations because they are the properties of the sensations which possess them in the states of non-emotion, too.
The affects in emotions，they should be the remainder of the various emotions when all their sensations were removed. In the emotions, obviously, besides those sensations there are also the subjective experience of pleasure or displeasure and the corresponding mental state of like ro dislike that are prevalent for all emotions. And they are what we can not find in the sensations that occur alone in the state of non-emotion. So they should be the mental entities of affect. And they are the essential component of emotion because they are prevalent for all kinds of emotions. In neural basis, some structures in limbic system that are known as closely linked to emotions such as amygdala, hypothalamus and so on or part of them，might be the neural bases of affect. It has been known that these neural structures receives inputs from all kinds of receptors and different areas of the cerebral cortex，and it is diffuse that their projections of cerebral cortex. So the affect has no special receptors, special neural pathway and special cortical areas. It has been found that the subjective natures of emotion (pleasure or displeasure) have specific neurochemical bases，and it is demonstrated that the increase or decrease of dopamine content in the brain are related respectively to the feelings of pleasure or displeasure. Likewise, the neurochemical bases are probably also belong to affect. If considering the neural basis of affect is ancient and non-specific (the specifity of neurochemical bases only embody in pleasure or displeasure），and considering the sensations play an important role in the distinctive feature of emotions，the mental entity of affect may be only the simpler feeling of pleasure or displeasure that undifferentiated and has different intensities ( similar to Leventhal’s “just a simple negative or positive affect”）. And the mental states of like ro dislike may be inherent in the feelings of pleasure and displeasure. That is, it can be said that the mental entity of affect is the kind of general diffusibity feeling which having only the two features of nonspecific pleasure and displeasure and their intensities, as well as the mental state of like /enjoy (the mental tendency of wish to keep it )ro dislike/repulsion(the mental tendency of wish to abate it ) that we can experience them in any emotions.
In summary，there are many kinds of sensations that often shows up in emotions. They can reflects the various objective features of body and external objects respectively. Their own have no the subjective nature of pleasure or displeasure. And they can not only involve in emotions but also be separate from emotions. The affect is prevalent for emotions, it has only the two mental properties of pleasure and displeasure that different intensities, and is accompanied by the mental states of like ro dislike respectively，but does not reflect any objective features of objects. That is，the sensation has only the objective features but has no subjective natures; the affect has only the subjective natures but has no objective features. So, if emotion is made up of the two different mental entity of sensation and affect by reason of they are activated simultaneously or in succession, it is inevitable that it will makes the affect as if has the objective features and makes the sensation as if has the subjective natures. In particular, because of the affect itself has no the objective feature of source or location (as its opposite, by sensations, we can feel a object lying on a part of our body,or a color belongs to an object before our eyes,etc), the mental entity of affect will be appended to sensations when it is combined with sensations to form a emotion. That is, it turns the pleasure or displeasure which are the feeling of affect and their intensity translate into the sensations which heve the features of source and location, and it turns the mental states of like ro dislike for affect into the like ro dislike for the objects of sensations from body and outside, and it is indistinguishable in consciousness just as we are unaware of the visual texture actually comes from sense of touch. That is the psychologic phenomena of affect objectified. On the other hand，the sensations (particular the body sensations)in emotion that in different forms of assembling also make their mental properties are appended to the feeling of affect, it makes the simple affect that have only two mental properties of pleasure or displeasure as if has a diversity，thus forming all sorts of emotions. For instance, those sensations result from body change such as muscular tension, a rise in heart rate and so on which may be caused by the motivation of hide or run away and other factors，by reason of they are always, in a form of assembling fixed basically, integrate with the perception of a particular type of situation and an affect of displeasure that produced by the perception, thus they have become part of the unique mental configuration of the emotion of fear, and make the simple affect of displeasure as if has a distinguishable feature.
As for the motivations that embody in many emotions, because of they is organized that they have a directivity of targets a specific object (this is relate to sensation), and they are also under the control of the mental state of like ro dislike (this is related to affect), it should be the mutual product of sensation and affect when they have integrated. And they may rely on past experiences. If motivation is the organized drive, the mental states of like ro dislike in emotions are this drive. It is generally acknowledged that the sensation reflects the objective features of body and outside objects, and the essential function of emotion reflects the organism’s inherent needs. The essential function of emotion should be only belong to affect that as the essential component of emotion; and the happen-evolution of sensations are serve for the affect. It may be because of the combination of affect and sensation, enable maki connections between our inherent needs and objective things, thus can forming the specific motivation by experience. For instance, a simple fear, its mental component including，first，the sensation of present object and a strong affect of displeasure，their combination makes the mantal state of affect that dislike/rejection transfer(or ascribe) to the sensation of object, thus forms the motivation of shun the object. That is, in particular emotions, the general affect provides mental states of like ro dislike(drive) and the feature of intensity，the specific sensations provide the features of sources in body or outside object (direction), the combination of the two forming a behavioral motivation. So the adaptive function of emotions, in essence, in the mental state of like or dislike that are inherent in the affect component of emotions.
2.2. The objectification of affect in sensory feeling
The affect is also often mentioned when people talk about the sensory feelings such as pain, hunger, thirst, smell, taste, choking, temperature and sexual pleasure，etc. Johnston thinks that the common important property of all the emotions and sensory feelings is the evaluative feeling. Or, all of they show different hedonic tone, positive or negative 5. That is, like all the emotions，all the sensory feelings are also accompanied by the feelings of pleasure or displeasure and the mental state of like or dislike besides their own specific component. In neural basis, studies have shown that the productions of all the sensory feelings, there are the neural informations of sensory pathways reach the cerebral cortex, and are also other neural informations reach limbic system that as emotional processing area. This suggests that in mental entity and neural basis，the feelings of pleasure or displeasure in sensory feelings may be essentially the same with the affect in emotions. Thus, all the sensory feelings may be also the complex feeling consist of the sensations of cortex and the affect of limbic system.
Take the pain for example，studies show that the Lateral spinothalamic tract has two pathways（fast and slow）for nociceptive information to reach the brain. The information of fast pathway travel to the somatosensory cortex via thalamus (specific sensory channels), it produces a well-localized sharp pain (also called fast pain or first pain), but we do not feel the pain is very fierce. This pathway also produces the sensation of injury type. The information of slow pathway travel to the limbic system via hypothalamus，it produces a fierce and intolerable burning pain (also called slow pain or second pain),and companion has a so-called affective component of pain6. Other studies have show that the slow pathway is just the mediated pathway of the affective component of pain7. Obviously,when the slow pain in limbic system occurs(it is about 0.5s slower than the fast pain ), the sharp pain and the sensations of site and injury type in somatosensory cortex are still exist，only added on the character of slow pain to them. It indicates that a complete sensation of pain is the complex feeling consist of the sensations of sharp pain, site，injury type in cortex and the burning pain and its affective component (i.e., affect) in limbic system. If considering the facts that any stimulus applied directly to the cerebral cortex can’t causes pain, as well as some clinical operation do not need anesthesia in the sensory pathways that lead to cortex 8, we have reason to believe that the sharp pain in cortex that “do not feel very fierce” may be just a neutral specific sensation of body the same as the sensations of site and injury type，which itself do not possess the nature of “feel afflictive” that in the experience of pain, but because of the subsequent affective component of pain in limbic system is superposed with it, this neutral sensation of body as if has a nature of afflictive (i.e., a form of affect objectified), thus forming so-called the burning pain that has both a specific sensation of body and a strong feeling of displeasure and its mental state of repulsion，that is a true pain. And it combines with the sensations of site and injury type to forms a complete so-called pain sensation. Craig even thinks even, “Pain can be either unpleasant (as usual) or pleasant (as when it relieves an intense itch). 9 ” The pain he described here may be only suitable for the cortical component of pain sensation. Clinical study found that if a stimulus that can cause normal person’s pain sensation applied to the patients with congenital analgia，they can recognize the stimulating site of skin and picotement, but can not feel pain6（obviously, there is also no the feeling of displeasure and the mental state of repulsion); while the patients with somatosensory cortex damage will appear the planotopokinesia of pain stimulus, but can produce the feeling of displeasure and withdraw behavior (also, this feeling of displeasure won’t have the characters of bodily pain, but it probably resembles a affect in emotion, and it has even combined with others sensations to form a emotion). This indicates that normal person’s pain sensation may be the former site and anothers neutral sensations from body plus the latter affect of displeasure. And both can be separated.
Likewise, in the higher mammals,olfactory center is located in the frontal cortex，and the olfactory message is also transmits to limbic system such as amygdala and cingulate gyrus；the gustatory message is also transmits to hypothalamus and central amygdaloid nucleus when it is transmit to insular cortex; the temperature sensation be known as the result of the integration between limbic system and somatosensory cortex. Obviously, these sensory feelings are accompanied by a obvious feeling of pleasure or displeasure,this feeling should be their the component of affect in limbic system. So these sensory feelings may be also the whole feeling consist of the sensations in cortex and the affect in limbic system. Furthermore，from the view of phenomenon, these sensory feelings also showed that their sensation and affect can be separated. For instance, the“sensation”of“cool” feels pleasant if your body is hot, but it feels gnawingly unpleasant if you are chilled9；and a taste you usually enjoyed， it can become disgusting at times.
It is generally believed that the subjective nature（pleasure or displeasure）of sensory feelings accord with the biological significance（benefit and harm ）to organism. For instance, these unpleasant feelings such as pain, foul odors, cold, hunger and thirst，all they meaning that the organism is or may be injured or in the state of physiologic deprivation; while those pleasant feelings such as sweet, satiety, “quench thirst”, warmth, sexual pleasure and so on,all they meaning that the organism is nourished, recovered from deprivation and its species is reproduced5. And some sensory feelings are regulated by immediate physiologic needs8. For instance, the fresh water that normally tasteless can become very sweet when the body has a serious water shortage. Some studies also suggest that the messages which are related with the biological significance to organism can also reach the brain by humoral signals and engender feelings2. For instance, when we are hungry, sometimes we feel an uneasiness and even headache，it is because of the signal of blood sugar level significantly reduced reach the brain via the bloodstream；and during puberty, we often feel body is light and in a happy mood, it’s because of much sex hormone flow into the brain5. The consistency between sensory feelings and the biological significance to organism, what it reflects should be the consistency between the affect and the biological significance to organism. For instance, we drink a cup of iced drink when we are hot and thirsty，on the one hand, this stimulation which is good for the body can engenders the pleasant sensory feelings (include whose specific sensation and pleasant affect )such as sweet and the “thorough cool” from mouth，esophagus and stomach，on the other hand, because of the complement of water in blood and generates a retrieval change in blood chemistry, it can too produces pleasant affect in the brain, and will be appended on the specific sensory components of the tastes and temperatures and other sensations of body that produced when the ice drink sinks. Thus forms the actual feeling of “quench thirst”, and in which makes the mental state of like that inherent in pleasant affect (or the liking for pleasant affect mentally) converted into the liking for the specific sensory components of the gustation, thermoesthesia and other sensations of body，and appear the consistency between the subjective nature of sensory feelings and the biological significance to organism.
Therefore，all kinds of sensory feelings may be equally the complex feeling consist of the two separable mental entities of the sensation in cortex and the affect in limbic system. And their combination makes the affect of pleasure or displeasure in the brain possesses the source of body and other sensory features, and shows the psychological phenomenon of affect objectified. And this phenomenon allow us to consciously make the regulation of life by sensory feelings. For instance,in the pain sensation,the combination of the mental state of repulsion for the strong unpleasant affect and the body sensations makes us can produce avoidance behavior by experiences,to avoid bodily injury (such behavior might become the rapid reaction of conditioned reflex in the future). As in emotions，the adaptive function of sensory feelings also roots in whose mental state of like or dislike that contained in affect.
3. A possible mechanism: the production of mental affect is the reactivation of physiologic affect
From the above we can see that it is possible that all the emotions and sensory feelings are the complex feeling consist of sensation and affect. And there may be consistency and the same origin in mental entity and in neural basis between the affect in sensory feelings ( the affect in sensory feelings and the affect that arise from others physiologic processes are hereinafter referred to as physiologic affect because of they often arise from direct physiologic stimulus or this stimulus has actual or potential physiologic significance for organism )and the affect in emotions (hereinafter referred to as mental affect because of it is usually produced by mental activity). Now it is certain that we have the innate neural mechanisms that produce the physiologic affect, as the neural mechanism of pain sensation mentioned above. In the sensory feelings, when a stimulus produces the sensations through distinct sensory channels,it also directly produces the affect in limbic system，this combination of the two forming various whole sensory feelings. And that，various stimuli have significant consistency with the nature of affect(pleasure or displeasure) that they produced. Therefore，it is no doubt that the physiologic affect can be produced by innate mechanism. But in the emotions, as we know, the emotions are usually produced by the visual and auditory information as well as mental activity. Unlike the sensory feelings, there is lack of the consistency between the subjective nature of emotions and the sensory inputs, sometimes even opposite. This also means that it has not consistency between the nature of mental affects and the sensory inputs. Therefore，it is very possible that we have no the innate neural pathways direct corresponding to any environmental stimulus that can produces ous mental affect. While if the mental affect is activated by acquired mechanisms, this activation of affect must be a conditioned activation. So, what is the unconditioned one which as the basis of this conditioned activation? Based on the hypothesis of the emotion and sensory feeling are consist of the two detachable mental entities of sensation and affect, and on the truth that some neural structures in limbic system are the common neural bases of sensory feeling and emotion that we have already known, we can deliver the assumption: for an individual, the production of his every mental affect is the reactivation of his physiologic affect at first. Thus the mental affect that as a conditioned response has a possible basis of the unconditioned response.
It is universally recognized that conditioned reflex can be established between any the different nerve processes that take place at the same time or in succession，including between the nerve processes of cognition, emotion and sensory feeling, even between mental processes and physiologic change. It is well known that it is a conditioned reflex when a dog sees food to produces saliva. This is because of the dog’s vision process about food had established nerve connection with its correlated process in hypothalamus that control salivation due to they take place at the same time or in succession when it was eating in the past，when the dog see food again, in certain conditions (as starvation), it will cause the conditioned reflex of the correlated nerve process in hypothalamus by this vision process, to produces saliva excretive. Unfortunately，it has never been reported in the literatures that whether the dog was also very happy at that time( as we are both of run at the mouth and very happy when we see plenty of waxberry on a tree under we are hot and thirsty for a long time). But from the performance of any dog when it sees somebody brings its food，we can infer that the dog also had a emotion of happy when it salivates. Although we can not confirm dog’s the affect in its this happy emotion is the reactivation of the physiologic affect in its the gustation,smell and nutritive process that produced when it eated in the past, but at least it’s a possibility. That is, when dog’s vision process about food activates the nerve process of hypothalamus in limbic system that control salivation, it might also activates the old physiologic affects in the sensory feelings of gustation and olfaction etc that also in limbic system and had been connections with it，and the affects combines with the present visual images and other sensations to form the happy emotion. Then, according the similarities on brain structures and their function between human and other mammals, as well as conditioned reflex is the common workings of neural activities, we can extend this possibility into the state: because of our the process of a visual or auditory is simultaneous (or in succession) with our the process of a sensory feeling, when we perform the similar visual or auditory activity again in the future, it may activate the old physiologic affect which in this sensory feeling，thus the mental affect is occured.
For instance, one hot day, we are very thirsty after a long walk, just then we suddenly get a long cool drink, we immediately feel very pleased. It means that within our brain an intense pleasant affect is produced just by the visual stimulus before we began to drink the cool drink（before we have received the physiologic stimulus）just through the visual stimulation，and the affect has been combined with present visual images and other mental contents to form this pleased emotion. This mental affect in the pleased emotion may be the reactivation of the physiologic affect in the past sensory feeling of “quench thirst”. The possible generation mechanism of this mental affect is that due to we often saw the cool drink in a cup or bottle when we got the feeling of “quench thirst” since our childhood, it makes the possibility that the two nerve processes of the related visual activity and the feeling of "quench thirst”can arouse each other’s conditioned response under proper conditions. Thus, later when we suddenly get a cup of cool drink under we are very thirst, the new similar visual perception could activate the previous feeling of quench thirst or part of its nerve process, that is, or it might only activate the affect component of the feeling of quench thirst( we have seen that the sensation and affect in sensory feeling are detachable, and their nerve bases are housed in different brain areas, so it is possible that their conditioned reactions can be produced, independently, by other perception processes ), and combines with it to form a new complex feeling that is the emotion of pleased which has both a pleasant affect and the visual image of a long cool drink, or also has the perceived contents of the event or persons that enable us to get the cool drink. And in this emotion we make our liking for the pleasant愉 affect converted into the love for the cool drink, event or persons.
For another example, looking at the relationship between pain sensation and fear. Although there are some cases of conditioned pain sensation in clinical practices, such as a ballet dancer, her toes pain as soon as she heard Tchaikovsky’s Swan Lake10, but this type of phenomenon is very rare. The conditioned response of pain sensation is usually displayed in another form. That is, it is generally not a original pain sensation of body that produced by the conditioned stimuli related to pain, but usually is the emotion of fear. Studies have shown that almost any kind of pain sensation can translates into fear quickly. For example,a tone together repeatedly with electric shock to animal foot, this tone can induce animal fear rather than pain sensation；a visual perception of fur together repeatedly with a pain sensation,the visual perception of fur can also induce fear. Another situation is if the strong noise appears when a baby see a animal, after many repetitions, as soon as the animal arise, the baby is fear, rather than cause his sensation of strong noise. Johnston summed up these results of classical conditioned reflex：the common component for strong noise and pain sensation is their feeling of displeasure, namely their negative hedonic tone; what the conditioned stimulus produces is the hedonic tone that once related with it，rather than a specific sensation. As a result of the acquired linkage between conditioned stimulus and negative hedonic tone, the fear is produced5. If use the concept of this paper, it can be interpret this phenomenon as: the conditioned response of pain sensation is usually just the affect component of the pain sensation (pain affect) rather than a whole pain sensation. And it is the pain affect which is activated by conditioned stimulus integrate with the sensation of conditioned stimulus to forms the emotion of fear (or the initial feature of the emotion of fear. There will be the sensory feedback of the body changes of fear soon after). For example, the fear which produced when a child sees nurses in the hospital, in which the component of affect may be the reactivation of the pain affect(a intense unpleasant affect) in the pain sensation that induced by injections in the past. Its possible generation mechanism is that because of the pain sensation and the visual perception of nurses in white was always appeared together when he received injections in the past, the neural connection would be established in his brain between the visual perception and the pain affect. So, in certain conditions, when the visual stimulus of a nurse appear again and it activate tis old similar visual perception (it has been known that the production of visual perceptions depend on the reactivation of old similar visual perceptions）, the old visual perception also causes the reactivation of pain affect in limbic system that have been established neural connection with it, so the intense unpleasant affect is produced. At the same time，possibly as a result of the influences of some behavioral motivations（as the motivation of run away ) , intense affect and other factors, a series of activities in the nervous system of muscle exercise and autonomic nervous system are produced, so excites the body changes of muscle, heart beat, respiration and so on, and they produce new nerve impulses and are transmitted to his brain to form the sensations of muscular tension, heart pound and polypnea, etc. When the above three mental contents that occured at the same time are combined together, thus form his this emotion of fear that there are a visual image of nurse, an intense unpleasant affect and those sensations of body. And in this complex feeling，he makes his mental states of repulsion and dislike for his own unpleasant affect converted into his avoidance and abhor for the nurse，that is，a afraid of nurse.
The above is a tentative explanation of the physiologic affect is the basis for the production of mental affect. If it is a truth of psychological phenomenon, it is easy to imagine that when the initial neural connections have been established between the physiologic affects in limbic system and those basic cognitive forms such as visual and auditory images, it builds a bridge for the mechanism that produces mental affect through more complicated cognitive processes (including the activities of language and thought that are based on the sensations of vision and hearing) ，thus enable the physiologic affect is indirectly activated in more roundabout and intricate ways，and it combine with the new sensations to form all kinds of complicated emotions. Perhaps it’s just this mechanism that makes the mysterious emotion as the water which has a source，and makes our emotional need can be connected with our physiologic need, and makes the emotional value of object can be consistent with the biological significance of our organism. Just as what Johnston said,“classical conditioning convert hedonic tone from important biological events to portentous events,and based on which the second set of reward and punishment system is produced. 5”
4. The production mechanism of the body changes of emotion
Obviously, the sensations of body states are derived from the neural signals of body changes.The major body changes that often accompanying emotions include muscular tension,a rise in heart rate， polypnea，blood pressure heighten，gastrointestinal digestion inefficient，palms hot and so on. From the view of phenomenon, there are two major features to emotional body change: (1) Under the comparable intensity, these emotions which are accompanied by the obvious behavioral motivation or motion intention will be more strong body changes, like the fear and anger that usually are accompanied by the motivations of run away or attack and some specific motion intentions. While those emotions which we need not answer them by drastic motions, or we only need to enjoy them, whose body changes are relatively low，like sadness, happiness and pleased，etc 11.（2）Any emotion has strong body change if which has a high intensity, the more strong an emotion, the more strong its body change. For instance, the emotion of happiness which without motivation also has a high heart rate when it has a very strong intensity. These suggests that the emotional body changes seem related to the influence of the direct motion intentions or the behavioral motivation that contain motion intentions on motor system, as well as to the activated intensity of some neural structures in limbic system which produce emotions. If we take into account these and the universality of the phenomenons of conditioned reflex in nervous system, as well as the “associability” of sympathetic nervous system that controls body changes, the production of emotional body changes might have the following several mechanisms:
1. The influence from motion intentions. Obviously, the body changes occur not only in the state of emotion, but also when we ran up the many flights of stairs or playing sports. Sports physiology experiment have shown that when people are imagining doing sports, there are similar body changes compared with the actual body sports，merely decrease in intensity. For instance, when we are imagining curl our arm inwards, can produce small contractile activity in the arm flexor 12. It suggests that our motion intention too can produce some degree of the body changes that produced by actual body sports (especially in the intention is quite intense) because of imagine a motion and a motion intention are both based on the activation of the representation system of actual motion in the brain. And further, the neural energy produced when we really want to do a motion( having a motion intentions) should be much higher than we only imagine a motion. And obviously, there are some the motivations of body behaviors and direct motion intentions (including of subconscious process) when we in some emotional atates, so that they might produce the relevant body changes that are similar with produced by actual body movement. For example, when we are fear, some intentions of defensive motions or the motivation of run away are usually very strong. Even if we were in hiding and still hardly daring to breathe, these intentions and motivations still strong, so may produces the body changes that are similar with in actual run away movement or defensive motions (and the body changes will be promote by the state of emotion. The possible causes for this promotion effect will be discussed in article 3 below). It is known that the physical arousal patterns of fear and anger have a lot of overlap，this is most probably because they are both accompanied by the intense motivation of body activity and the motion intention.
2. Conditioned body response. Sports physiology showed that before the training, as a result of the stimuli of athletic field environment and music, will cause the athletes to the conditioned reflexes such as a rise in heart rate, blood pressure rise, breath quickened and so on 13. That is, the body changes that produced by previous sports training in similar circumstance are caused by conditioned stimuli. Other studies have found that when people swimming in winter, before people enter the hypothermia，the regulatory mechanism of homoiothermism has been launched in advance by visual stimulus，and heat production is increased and heat dissipation is reduced 14. These conditioned reflex activities also called feedforward adaptive control，which seem to make the body responses have the foresight, and prepares for physiologic adjustment reaction as early as possible. But in essence，they are all as a result of the interplay between the two nervous system of the represents environments and the controls body changes in the brain, and what they reflect are the conditioned reflex that as a natural function of nervous system. (Obviously, the above these abilities of environmental stimulus to produce body changes ars not inherent in themselves, but rely on the reactivation of the old neural activities of represent environments that have been connection with body changes） Well then，it is known that the emotions are produced by situations, the situations are usually the environment or events that similarities with the environments or events which has produced our sensory feelings or emotions in the past. Thus, the same as these perceptions of environments, when the situational stimulation produces our emotion, it may also produces the body changes that produced in the similar state of emotion in the past，and this process is promoted by present state of emotion. For example，if we have had the drastic body movements of ran away or attacked and their body changes whan we were fear or anger in the past, it is possible to produces the conditioned responses of our those body changes under the new stimulus of the situation of fear or anger.
3. The epiphenomenon of the activation of affect in the brain. Because of the neural bases of affect and the part of autonomic nervous system within the brain that controls the body changes are both located in the core place in the brain, and there are extensive and interactive parallel neural connection between these neural structures8，when any one of these neural structures is activating, it may make the direct or conditioned influence on the others, especially under its activation intensity is high. Therefore，part of the because of the emotional body changes is the epiphenomenon of the activation of the affect in emotions. In addition, because of the anatomical placement neighborhood of these neural structures, as well as the activation of affect meaning that its neural energy is increased, it may be the causes of the promotion effect of the emotional state on the body changes that produced by the behavioral motivation, motion intention and environmental stimulus.
4. The main characters of autonomic nervous system are the associability and autonomy，whose performance in the body’s physiologic responses are they mutual coordination and influence each other. Thus, some body changes may be a cause of other body changes. For instance, the whole-body muscular tension of fear, if it persists for an appreciable time will consume a lot of energy, it certainly will heighten the activity of heart to pump blood, then there are the effects on respiratory system and other physiologic system.
In summary, because of there are extensive connection between various neural structures in the brain and the universality of the phenomenon of conditioned reflex, all the emotional body changes may be a joint result of the four mechanisms at least. The former two are the response that regulated by intention and conditioned response, they related to body movement, and belonging to the products of cognitive system and motor system. The 3 belonging to the epiphenomenon of the activation of affect in the brain. The 4 belonging to the autoregulation of autonomic nerve system. So-called the physical ready state of some emotional behaviors from “preparedness bypothesis”(as fight-flight reaction), they may actually be caused by these acquired causes. At least, even if we haven’t so-called the “innately preset devices” inherited from gene that produce the emotional body changes, our the same body changes can also be produced by situational stimulus under above these acquired and realistic mechanisms.
 Damasio, A. R. (1994) Descartes' Error: emotion, reason, and the human brain. Translator：Caifeng Mao. Beijing：Education & Science Press.
 Damasio,A.R.（1989）Time-locked multiregional retroactivation:A systems level proposal for the neural substrates of recall and recognition.Cognition，33:25-62.
Strongman,K.T.(2003) The Psychology Of Emotion: From Everyday Life To Theory 5th ed Translator：Li Wang. Beijing：China Light Industry Press.
 Victor S.Johnston.（2000）Why We Feel: The Science of Human Emotions. Translator: Saiqi Wong，etc. Shanghai: Science and Technology Press.
 Wuen Geng.(2003) Pain and Anguish：the explore of pain and analgesis. Shanghai: Science and Technology Press.
 Buwei Yu. (2006) Progress in pain mechanism Study. The Progress of Modern Clinical Medicine surgery：anesthesiology. Beijing：Science and Technology Document Press. 44-47.
 Jiourong Sun.（2001）Introduction to Brain Science. Beijing：BJ University Press.
 Craig, A.D.( 2003) A new view of pain as a homeostatic emotion. Trends in Neurosciences. 26: 303–7.
 Guanru Dai & Meng Dai.（2005) The Finding of Inverse Pain：the biological principles of pain and its application. Beijing：,Military Medical Science Press.
 James W.Kalat & Michelle N.Shiota.（2006）Emotion. Translator：Renlai Zhou. Beijing：China Light Industry Press.
 Jigang LI, Bao Tian. (2005) Physiological mechanisms of sports image theory mode and its application research. Journal of Wuhan Institute of Physical Education. 39，05.
 Xirang Yang (editor in chief ）. (2006) Practical Athletic Physiology. Beijing：Beijing Sport University Publishing House.
 Ling Kong（editor in chief）.（2008） Normal Human Body Function. Hefei：University of Science and Technology of China Press.