Test 6 sensation and perception

Describe the pathways from the skin to the cortex.)

) Because the signals in the spinal cord have crossed over to the opposite side of the body, signals originating from the left side of the body reach the thalamus in the right hemisphere of the brain, and signals from the right side of the body reach the left hemisphere. Figure 15.3 The pathway from receptors in the skin to the somatosensory receiving area of the cortex. The fiber carrying signals from a receptor in the finger enters the spinal cord through the dorsal root. The signals then travel up the spinal cord along two pathways: the medial lemniscus and the spinothalamic tract. These pathways synapse in the thalamus and then send signals to the somatosensory cortex in the parietal lobe. The idea of two pathways conducting cutaneous signals to the thalamus and then to the somatosensory cortex supports the idea that different pathways serve different sensations. But it is important to realize that the cutaneous pathways and structures within the brain that are far more complex than the picture in Figure 15.3.

Identify the functions of the skin.

In addition to its warning function, the skin also prevents body fluids from escaping and at the same time protects us by keeping bacteria, chemical agents, and dirt from penetrating our bodies. Skin maintains the integrity ofwhat's inside and protects us from what's outside, but it also provides us with information about the various stimuli that contact it.

Explain how naming an odor affects perception of the odor.

Odors such as "anise," "orange," and "lemon" were proposed as we tried to identify its smell, but it wasn't until someone turned the bottle around and read the label on the back that the truth became known: "Aquavit (Water of Life) is the Danish national drink—a delicious, crystal-clear spirit distilled from grain, with a slight taste of caraway." When we heard the word caraway, the previous hypotheses of anise, or-ange, and lemon were transformed into caraway. Thus, when we have trouble identifying odors, this trouble may occur not because of a deficiency in our olfactory system, but from an inability to retrieve the odor's name from our memory

Which one is associated with perceiving rapid vibrations?

Pacinian corpuscle

a) Which one is associated with perceiving fine texture when a finger is moved across the texture?

Pacinian corpuscle

Describe how odor objects are represented and how memory affects this organization.

This is like the neurons that represent a new mem-ory, which aren't yet linked (see Figure 16.23a). At this point you are likely to have trouble identifying the odor and might confuse it with other odors. But after a number of exposures to the flower, which cause the same activation pattern to oc-cur over and over, neural connections form, and the neurons become associated with each other (Figure 16.24d). Once this occurs, a pattern of activation has been created that represents the flower's odor. Thus, just as a stable memory becomes es-tablished when neurons become linked, odor objects become formed when experience with an odor causes neurons in the piriform cortex to become linked. According to this idea, when the person in Figure 16.14 walks into the kitchen, the activa-tion caused by the hundreds of molecules in the air become three linked networks of activation in the PC that stand for coffee, orange juice, and bacon.

Describe evidence of early touch perception in infants.

Touch is the earliest sensory modality to develop, emerg-ing just 8 weeks after gestation, then developing and becom-ing functional within the womb, and being ready for action at birth (Cascio et al., 2019). Touch and speech are the earliest forms of parent-child interaction, but in contrast to speech, which is a one-way interaction at the beginning, touch is two-way. This is illustrated by the automatic hand closure response to objects (like a parent's finger, for example) placed in the in-fant's palm (Bremner & Spence, 2017). What makes the story of infant touch even more inter-esting is that it begins in the womb. From 26 weeks after gestation, the fetus begins responding to vibration with heart rate acceleration. Later, the fetus begins bringing a hand to the face, and in the last 4 to 5 weeks before birth, begins touching the feet. Viola Marx and Emese Nagy (2017) showed, using ultrasound films, that in the third trimester, the fetus responds when the mother's abdomen is touched. Even more interesting is what happens with twin fetuses. They are, of course, in close proximity in the womb, so could touch each other accidentally. But ultrasound films have cap-tured a fetus not only moving its hands to its mouth, but also "caressing" the head of its sibling (Castiello et al., 2010) (Figure 15.34). The importance of the infant's ability to touch and sense touch becomes magnified when it is born, because this is when touch becomes social. Sixty-five percent of face-to-face inter-action between caregiver and infant involves touch (Cascio et al., 2019). And there is evidence linking touch felt by infants to the social touch experienced by adults that involves CT af-ferents (p. 371). For example, Merle Fairhurst and coworkers (2014) found that 9-month-old infants respond to movement of a brush along their arm with a decrease in heart rate (indi-cating a decrease in arousal) if the brush is moved across the arm at 3 cm per second, which is in the range that activates CT afferents. Lower (0.3 cm/sec) or higher (30 cm/sec) rates did not cause this effect. vidence that CT afferents may become involved just after birth is provided by Jetro Tuulari and coworkers (2019), who found that presenting soft brush strokes to the legs of 11-to 16-day-old infants activates the posterior insula (Figure 15.26), which is associated with social touch in adults. And just as social touch can reduce pain in adults, the skin-to-skin contact that occurs when newborn infants are held close by the mother (sometimes called kangaroo care) has been shown to cause an 82 percent decrease in crying in re-sponse to a medical heel lance procedure (Gray et al., 2000; also see Ludington-Hoe & Husseini, 2005). The most important outcome of an infant's experience of social touch is how it shapes social, communicative, and cogni-tive development in the months and years that follow (Cascio et al., 2019). A dramatic demonstration of this effect of social touch is provided by premature infants who are deprived of early social touch when they are separated from their mothers and placed in incubators. When these premature infants are massaged, they have more weight gain, better cognitive devel-opment, better motor skills, and better sleep than premature infants who are not massaged (Field, 1995; Wang et al., 2013). At the beginning of this Developmental Dimension we noted that touch and speech are the earliest forms of parent-child interaction. We saw in Chapter 14 that infant-directed speech (IDS) has many beneficial effects on the developing infant (p. 353). We've seen here that social touch has its own positive effects. Clearly, using infant-directed speech in conjunction with social touch is a pow-erful combination for enhancing the course of an infant's development.

Describe the Proust effect and related research findings.

Proust's rather dramatic description of how tasting a cookie unlocked memories he hadn't thought of for years is called the Proust effect. This passage captures some character-istics of Proustian memories: (1) Memories were realized not by seeing the cookie but by tasting it; (2) the memory was vivid and transported Proust back to a number of places from his past; and (3) the memory was from Proust's early childhood. can happen with any scented item and more often had item more likely more memories will ocur with scent.

Describe the direct pathway model of pain and discuss problems with this model.

. Ac-cording to this model, pain occurs when nociceptor recep-tors in the skin are stimulated and send their signals directly from the skin to the brain (Melzack & Wall, 1965). But in the 1960s, some researchers began noting situations in which pain was affected by factors in addition to stimulation of the skin. One example was the report by Beecher (1959) that most American soldiers wounded at the Anzio beachhead in World War II "entirely denied pain from their extensive wounds or had so little that they did not want any medication to relieve it" (p. 165). One reason for this was that the soldiers' wounds had a positive aspect: they provided escape from a hazardous battlefield to the safety of a behind-the-lines hospital. Another example, in which pain occurs without any transmission from receptor to brain, is the phenomena of phantom limbs, in which people who have had a limb am-putated continue to experience the limb (Figure 15.23). This perception is so convincing that amputees have been known to try stepping off a bed onto phantom feet or legs, or to at-tempt to lift a cup with a phantom hand. For many, the limb moves with the body, swinging while walking. But perhaps most interesting of all, it is not uncommon for amputees to experience pain in the phantom limb (Jensen & Nikolajsen, 1999; Katz & Gagliese, 1999; Melzack, 1992; Ramachandran & Hirstein, 1998).

Discuss cortical mechanisms responsible for tactile acuity.

. Table 15.1 indi-cates the two-point threshold measured on different parts of the male body. By comparing these two-point thresholds to how different parts of the body are represented in the brain (Figure 15.5a), we can see that regions of high acuity, like the ingers and lips, are represented by larger areas on the cortex. As we mentioned earlier, when we described the homunculus, "magnification" of the representation on the brain of parts of the body such as the fingertips parallels the magnification factor in vision (p. 75). The map of the body on the brain is enlarged to provide the extra neural processing that enables us to accurately sense fine details with our fingers and other parts of the body. Another way to demonstrate the connection between cortical mechanisms and acuity is to determine the receptive fields of neurons in different parts of the cortical homuncu-lus. Figure 15.10, which shows the sizes of receptive fields from cortical neurons that receive signals from a monkey's fingers (Figure 15.10a), hand (Figure 15.10b), and arm (Figure 15.10c), indicates that cortical neurons representing parts of the body with better acuity, such as the fingers, have smaller receptive fields. This means that two points that are close together on the fingers might fall on receptive fields that don't overlap (as indicated by the two arrows in Figure 15.10a) and so would cause neurons that are separated in the cortex to fire (Figure 15.10d). However, two points with the same separation when applied to the arm are likely to fall on recep-tive fields that overlap (see arrows in Figure 15.10c) and so could cause neurons that are not separated in the cortex to fire (Figure 15.10d). Thus, the small receptive fields of neurons receiving signals from the fingers translates into more separa-tion on the cortex, which enhances the ability to feel two close-together points on the skin as two separate points.

Discuss research on the physiology of tactile object perception. Also describe research on the role of attention in haptic perception.

1. role of attention in haptic perception. There are also neurons in the monkey's somatosensory cortex that respond when the monkey grasps a specific ob-ject (Sakata & Iwamura, 1978). For example, Figure 15.17 shows the response of one of these neurons. This neuron responds when the monkey grasps the ruler but does not re-spond when the monkey grasps a cylinder or a sphere (see also Iwamura, 1998) re scanned across a monkey's finger. In the tactile-attention condition, the monkey had to perform a task that required fo-cusing its attention on the letters being presented to its fingers. In the visual-attention condition, the monkey had to focus its attention on an unrelated visual stimulus. The results, shown in Figure 15.18, show that even though the monkey is receiv-ing exactly the same stimulation on its fingertips in both condi-tions, the response is larger for the tactile-attention condition. Thus, stimulation of the receptors may trigger a response, but the size of the response can be affected by processes such as attention, thinking, and other actions of the perceiver.

Discuss genetic differences in taste perception.

Advances in genetic techniques have made it possible to determine the locations and identities of genes on human chromosomes that are associated with taste and smell recep-tors.

Discuss the major functions of pain and the consequences of not being able to feel pain.

As we mentioned at the beginning ofthis chapter, pain functions to warn us ofpotentially damaging situations and therefore helps us avoid or deal with cuts, burns, and broken bones. People born without the ability to feel pain might become aware that they are leaning on a hot stove burner only when they smell burn-ing flesh, or might be unaware of broken bones, infections, or internal injuries—situations that could easily be life-threatening (Watkins & Maier, 2003). The signaling function of pain is re-flected in the following definition, from the International Asso-ciation for the Study of Pain: "Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage" (Merskey, 1991). think little girl from video in class who could not feel pain

Compare and contrast receptors of the visual system and the olfactory system.

Both of them use receptors but there are many more in olfactory system than visual system which is important for sensation and perception also remember receptors for olfactory are exposed to elements.

Describe the exploratory procedures used in haptic exploration.

Cortical neurons are specialized- Neurons in the ventral posterior nucleus, which is the tactile area of the thalamus, have center-surround receptive fields that are similar to the center-surround receptive fields in the lateral geniculate nucleus, which is the visual area of the thalamus (Mountcastle & Powell, 1959; Figure 15.15) Cortical Responding Is Affected by Attention Cortical neurons are affected not only by the properties of an object but also by whether the perceiver is paying atten-tion. Steven Hsiao and coworkers (response of neurons in areas S1 and S2 to raised letters that were scanned across a monkey's finger. In the tactile-attention condition, the monkey had to perform a task that required fo-cusing its attention on the letters being presented to its fingers. In the visual-attention condition, the monkey had to focus its attention on an unrelated visual stimulus. The results, shown in Figure 15.18, show that even though the monkey is receiv-ing exactly the same stimulation on its fingertips in both condi-tions, the response is larger for the tactile-attention condition. Thus, stimulation of the receptors may trigger a response, but the size of the response can be affected by processes such as attention, thinking, and other actions of the perceiver.

Name and define the three parts of the somatosensory system.

Cutaneous system-touch and pain caused by stimulation of the skin Proprioception-ability to sense position of body and limbs Kinesthesis-ability to sense movement of body and limbs

Describe the four kinds of papillae of the tongue and where they are located.

Fungiform=shaped like mushrooms mostly at tip and sides especially sensitive to taste also contain sensory cells for touch(texture of food) and temperature(hot or cold) Cicumvallate=back of tongue very large and only 7-12 yet each ahs several thousand taste busd Called circumvallate because surrounded by trench containing glands that rinse substances on receptors Foliate=folds on side(near back) Well developed in childhood but less pronounced in adults Folds catch saliva running down cheeks and direct to receptors FIliform=shaped like cones most common concentrated in center no taste buds(so no taste in center)

Describe research on empathy and brain responses to pain.

Goldstein's experiment demonstrated that holding someone's hand can reduce their pain. This has been described as effect of Figure 15.28 Setup for the Goldstein et al. (2018) experiment. See text for details. empathy, the ability to share and vicariously experience some-one else's feeling. In the hand-holding experiment, the person receiving the empathy experienced pain analgesia. We can also look at empathy from another point of view, by considering what is happening for the "empathizer," the person who is feel-ing empathy for the person who is in pain. In Chapter 7 we introduced the idea that observing an ac-tion can cause activity related to that action in the observer's brain. This was demonstrated in experiments studying mirror neurons in the monkey's premotor cortex, which fired both when the monkey picking up an object, such as food, and also when the monkey saw someone else picking up the food. Research on the somatosensory system has revealed similar phenomena. To introduce this phenomenon, let's first consider an experiment involving touch. Keysers and coworkers (2004) measured the fMRI response of a person's cortex to being touched on the leg. They also measured the response that occurred when that person viewed a film of an-other person being touched on the leg. Being touched caused a response in the person's primary somatosensory area (S1) and secondary somatosensory area (S2). Watching someone else being touched caused a response in S2, part of which overlapped with the response to being touched. Keysers con-cluded from the overlap in the areas that the brain trans-forms watching someone being touched into an activation of brain areas involved in our own experience of touch (see also Keysers et al., 2010). Another way to describe Keysers's results is, when we wit-ness someone else being touched, we don't just see touch, but we have an empathic response in which we understand the other person's response to touch through a link with our own experience of touch. This idea that observing someone else be-ing touched triggers brain mechanisms that might help us understand the other person's response to touch is impor-tant because there is also evidence that similar mechanisms operate for pain. Tania Singer and coworkers (2004) demonstrated the con-nection between brain responses to pain and empathy by bring-ing romantically involved couples into the laboratory and hav-ing the woman, whose brain activity was being measured by an fMRI scanner, either receive shocks herself or watch her male partner receive shocks. The results, shown in Figure 15.30, Figure 15.30 Singer and coworkers (2004) used fMRI to determine the areas of the brain activated by (a) receiving painful stimulation and (b) watching another person receive the painful stimulation. Singer proposes that the activation in (b) is related to empathy for the other person. Empathy did not activate the somatosensory cortex but did activate other areas that are activated by pain, such as the insula (tucked between the parietal and temporal lobes) and anterior cingulate cortex (see Figures 15.25 and 15.26). (Adapted from Holden, 2004) (a) Receive painful stimulation show that a number of brain areas were activated when the woman received the shocks (Figure 15.30a), and that some of the same areas were activated when she watched her partner receive shocks (Figure 15.30b). The main two areas activated in common were the anterior cingulate cortex (ACC) and the anterior insula (AI), both of which are associated with the af-fective component of pain (see Figure 15.26). To show that the brain activity caused by watching their partner was related to empathy, Singer had the women fill out "empathy scales" designed to measure their tendency to empa-thize with others. As predicted, women with higher empathy scores showed higher activation of their ACC. In another experiment, Olga Klimecki and coworkers (2014) had participants undergo training designed to in-crease their empathy for others and then showed them videos depicting other people experiencing suffering due to injury or natural disasters. Participants in the empathy-training group showed more empathy compared to a control group that hadn't received the training and greater activation of the ACC. Thus, although the pain associated with watch-ing someone else experience pain may be caused by stimula-tion that is very different from physical pain, these two types of pain apparently share some physiological mechanisms. (Also see Avenanti et al., 2005; Lamm et al., 2007; Singer & Klimecki, 2014.)

Discuss differences between being able to discriminate odors and being able to identify odors.

However, when they are asked to identify the substance associated with the odor, they are successful less than half the time (Desor & Beauchamp, 1974; Engen & Pfaffmann, 1960). However, when people are trained in identifying odors by be-ing told the names of substances when they first smell them and then being reminded of the correct names if they fail to name them correctly on subsequent presentations, they can eventually identify 98 percent of the substances (Desor & Beauchamp, 1974)

Describe the duplex theory of texture perception and research that supports this theory. Be sure to distinguish between spatial cues and temporal cues.

In 1925, David Katz proposed what is now called the duplex theory of texture perception, which states that our percep-tion of texture depends on both spatial cues and temporal cues (Hollins & Risner, 2000; Katz, 1925/1989). Spatial cues are provided by relatively large surface ele-ments, such as bumps and grooves, that can be felt both when the skin moves across the surface elements and when it is pressed onto the elements. These cues result in feeling differ-ent shapes, sizes, and distributions of these surface elements. An example of spatial cues is perceiving a coarse texture such as Braille dots or the texture you feel when you touch the teeth of a comb. Temporal cues occur when the skin moves across a tex-(c) Figure 15.11 (a) When a vibrating pressure stimulus is applied to the Pacinian corpuscle, it transmits these pressure vibrations to the nerve fiber. (b) When a continuous pressure stimulus is applied to the Pacinian corpuscle, it does not transmit the continuous pressure to the fiber. (c) Lowenstein determined how the fiber fired to stimulation of the corpuscle (at A) and to direct stimulation of the fiber (at B). (Adapted from Lowenstein, 1960) Surface Texture Surface texture is the physical texture of a surface created by peaks and valleys. As can be seen in Figure 15.12, visual inspec-tion can be a poor way of determining surface texture because seeing texture depends on the light-dark pattern determined by the angle of illumination. Thus, although the visually per-ceived texture of the two sides of the post in Figure 15.12 looks Figure 15.12 The post in (a) is illuminated from the left. The close-up in (b) shows how the visual perception of texture is influenced by illumination. Although the surface on the right side of the pole appears rougher than on the left, the surface textures of the two sides are identical. tured surface like fine sandpaper. This type of cue provides in-formation in the form of vibrations that occur as a result of the movement over the surface. Temporal cues are responsible for our perception of fine texture that cannot be detected unless the fingers are moving across the surface.

Discuss infant detection of odors and tastes, and describe early influences on the development of flavor preferences

Infants detect odors and tastes from basically birth which is tested by having them taste bitter or sweet. Babies get flavors through amniotic fluid which is how they learn what to eat and not. They prefer what parent prefers which is why it is so important to vary diet.

1. Describe how Ian Waterman's experiences illustrate the importance of touch.

It showed how having somatosensory system is so important for picking up objects grasping objects and movements in general without having to look at body parts.

Distinguish between the three different types of pain

Joachim Scholz and Clifford Woolf (2002) distinguish three different types of pain. Inflammatory pain is caused by damage to tissue or inflammation of joints or by tumor cells. Neuropathic pain is caused by lesions or other damage to the nervous system. Examples of neuropathic pain are carpal tun-nel syndrome, which is caused by repetitive tasks such as typ-ing; spinal cord injury; and brain damage due to stroke. Nociceptive pain is pain caused by activation of receptors in the skin called nociceptors, which are specialized to respond to tis-sue damage or potential damage (Perl, 2007). A number ofdifferent kinds of nociceptors respond to different stimuli—heat, chemical, severe pressure, and cold (Figure 15.22). We will focus on nocicep-tive pain. Our discussion will include not only pain that is caused by stimulation of nociceptors in the skin, but also mechanisms that affect the perception of nociceptive pain, and even some ex-amples ofpain that can occur when the skin is not stimulated at all

Which one is associated with perceiving motion across the skin?

Meissner corpuscle

a) Which one is rapidly adapting and close to the surface of the skin?

Meissner corpuscle

a) Which one is associated with the perception of fine details and texture?

Merkel receptor

a) Which two are located close to the surface of the skin?

Merkel receptor and Meissner corpuscle

Name and describe the four types of mechanoreceptors. Be sure to include whether they are close to the surface of the skin or deeper, size of their receptive fields, whether they are slowly adapting or rapidly adapting (and what this means), and types of perception for each one.

Merkel receptor-fires to continuous pressure, fine details and pressure shape close to surface of skin small receptive field slowly adapting meaning slower to change Meissner corpuscle close to skin fires to on and off rapidly adapting due to this handgrip motion and motion across skin small receptive fields Ruffini cylinder is a slowly adapting (SA2) fiber, which responds continuously to stimula-tion. are located deep in the skin (Figure 15.2), so they have larger receptive fields. The Ruffini cylinder is as-sociated with perceiving stretching of the skin, Pacinian corpuscle is a rapidly adapting fiber (RA2 or PC) which responds when the stimulus is applied or removed.larger receptive field deep in skin Pacinian corpuscle with sensing rapid vibrations and fine texture.

Discuss differences between nontasters and supertasters.

People who can taste PTC are described as tasters, and those who cannot are called nontasters. Additional experiments have also been done with a substance called 6-n-propylthiouracil, or PROP, which has properties similar to those of PTC (Lawless, 1980, 2001). Researchers have found that about one-third of Americans report that PROP is tasteless and two-thirds can taste it. What causes these differences in people's ability to taste PROP? One explanation for these differences is that people who can taste PROP have higher densities of taste buds than those who can't taste it (Bartoshuk & Beauchamp, 1994)

Discuss how expectations affect pain perception (including definition of the placebo effect).

Studies have also shown that a significant proportion of patients with pathological pain get relief from taking a placebo, a pill that they believe contains painkillers but that, in fact, contains no active ingredients (Finniss & Benedetti, 2005; Weisenberg, 1977). This decrease in pain from a substance that has no pharmacological effect is called the placebo effect. The key to the placebo effect is that the patient believes that the sub-stance is an effective therapy. This belief leads the patient to expect a reduction in pain, and this reduction does, in fact, oc-cur. Many experiments have shown that expectation is one of the more powerful determinants of the placebo effect (Colloca & Benedetti, 2005). Ulrike Bingel and coworkers (2011) demonstrated the ef-fect of expectation on painful heat stimulation presented by an electrode on the calf of a person's leg. The heat was adjusted so the participant reported a pain rating of 70, where 0 cor-responds to "no pain," and 100 to "unbearable pain." Partici-pants then rated the pain in a condition in which a saline solu-tion was presented by infusion (baseline) and three conditions in which the analgesic drug remifentanil was presented, but the participants were told (1) that they were still receiving the saline solution (no expectation); (2) that the drug was being pre-sented (positive expectation); and (3) that the drug was going to be discontinued in order to investigate the possible increase in pain that would occur (negative expectation). The results, shown in Table 15.2, indicate that pain was reduced slightly, from 66 to 65, in the no expectation condi-tion when the drug infusion began, but dropped to 39 in the positive expectation condition, then increased to 64 in the negative expectation condition. The important thing about these results is that after the saline baseline condition, the participant was continuously receiving the same dose of the drug. What was being changed was their expectation, and this change in expectation changed their experience of pain. The decrease in pain experienced in the positive expecta-tion condition is a placebo effect, in which the positive expec-tation instructions function as the placebo. Conversely, the negative effect caused by the negative expectation instructions Table 15.2 Effect of Expectation on Pain Ratings CONDITION DRUG? Baseline No expectation Positive expectation Negative expectation Source: Bingel et al., 2011. No Yes Yes Yes is called a nocebo effect, a negative placebo effect (see Tracey, 2010, for a review of placebo and nocebo effects). This study also measured the participants' brain activity and found that the placebo effect was associated with increases in a network of areas associated with pain perception, and the nocebo effect was associated with increases in activity in the hippocampus. A person's expectation therefore affects both perception and physiological responding.

Describe connections between the basic taste qualities and their gatekeeper functions.

Sweet is imortant for calories therefore is allowed in body and is preparing body for gi digestion. Bitter is rejected immediately to protect body from harm. Salty has sodium therefore when body is losing salt it will seek out salty foods(think after lots exercise or heat).taste can adapt to allow certain things like coffee which is bitter if desired.

Define haptic perception and identify three systems used in haptic perception. Explain how this relates to active and passive touch.

The active part of the demonstration involved haptic perception—perception in which three-dimensional objects are explored with the fingers and hand. (1) the sensory system, which was involved in detecting cutaneous sensations such as touch, temperature, and texture and the movements and positions of your fingers and hands; (2) the motor system, which was in-volved in moving your fingers and hands; and (3) the cognitive system, which was involved in thinking about the information provided by the sensory and motor systems. Haptic perception is an extremely complex process be-cause the sensory, motor, and cognitive systems must all work together. For example, the motor system's control of finger and hand movements is guided by cutaneous feelings in the fingers and the hands, by your sense of the positions of the fin-gers and hands, and by thought processes that determine what information is needed about the object in order to identify it., compared the experience of active and passive touch by noting that we tend to relate passive touch to the sensation experienced in the skin, whereas we relate ac-tive touch to the object being touched. For example, if some-one pushes a pointed object into your skin, you might say, "I feel a pricking sensation on my skin"; if, however, you push on the tip of the pointed object yourself, you might say, "I feel a pointed object" (Kruger, 1970). Thus, for passive touch you experience stimulation of the skin, and for active touch you experience the objects you are touching.

Describe the process of transduction for taste.

The ion flow across membrane changes based on taste receptors which causes transduction to occur.

Discuss how the medial lemniscal pathway and spinothalamic pathway differ.

The lemniscal pathway has large fibers that carry signals related to sensing the positions of the limbs (proprioception) and perceiving touch. These large fibers transmit signals at high speed, which is important for and reacting to touch. The spinothalamic pathway consists of smaller fibers that transmit signals related to temperature and pain. The case of Ian Waterman illustrates this sepa-ration in function, because although he lost the ability to feel touch and to sense the positions of his limbs (lemnis-cal pathway), he was still able to sense pain and temperature (spinothalamic pathway).

Explain how vibrations are perceived.

The mechanoreceptor that is primarily responsible for sensing vibration is the Pacinian corpuscle. One piece of evidence link-ing the Pacinian corpuscle to vibration is that recording from fibers associated with the corpuscle shows that these fibers re-spond poorly to slow or constant pushing but respond well to high rates of vibration. Why do the Pacinian corpuscle fibers respond well to rapid vibration? The answer to this question is that the presence of the corpuscle surrounding the nerve fiber determines which pressure stimuli actually reach the fiber. The corpuscle, which consists of a series of layers, like an onion, with fluid between each layer, transmits rapidly repeated pressure, like vibration, to the nerve fiber, as shown in Figure 15.11a, but does not transmit continuous pressure, as shown in Figure 15.11b. Thus, the corpuscle causes the fiber to receive rapid changes in pressure, but not to receive continuous pressure.

Describe how receptors for the chemical senses differ from receptors for our other senses (vision, hearing, and the cutaneous senses).

The receptors are exposed to environment for chemical senses unlike recpetors for heaing vision and cutaneous senses.

Explain what it means to describe pain as multimodal.

The sensory and affective components of pain can be distinguished by asking participants who are experiencing painful stimuli to rate subjective pain intensity (sensory component) and unpleasantness (affective component), as was done in the music study described in the previous section. When R. K. Hofbauer and coworkers (2001) used hypnotic suggestion to increase or decrease these compo-nents separately, they found that changes in the sensory component were associated with activity in the somatosen-sory cortex and changes in the affective component were associated with changes in the anterior cingulate cortex. Figure 15.26 shows these two areas and some other areas that have been determined from other experiments to be as-sociated with sensory (blue) and affective (green) pain expe-riences (Eisenberger, 2015).

Discuss receptor mechanisms responsible for tactile acuity.

We will illustrate this by first focusing on the connection between the Merkel receptor and associated fibers and tactile acuity. Figure 15.8a shows how the fiber associated with a Merkel receptor fires in response to a grooved stimulus pushed into the skin. Notice that the firing of the fiber reflects the pat-tern of the grooved stimuli. This indicates that the firing of the Merkel receptor's fiber signals details (Johnson, 2002; Phillips & Johnson, 1981). For comparison, Figure 15.8b shows the firing of the fiber associated with the Pacinian corpuscle. The lack of match between the grooved pattern and the firing indi-cates that this receptor is not sensitive to the details of patterns that are pushed onto the skin. Remember fingertips work best for this in humans(most sensitive to details)

Describe research showing connections between social touch and pain.

We've seen that being a recipient of social touch is often per-ceived as pleasant (p. 372). We now describe an experiment by Pascal Goldstein and coworkers (2018) that was inspired by Goldstein's observation that holding his wife's hand during the delivery of his daughter decreased his wife's pain. Figure 15.28 shows the position of the two participants in the experiment that studied this observation in the laboratory. Romantically involved couples wore electrode arrays on their heads to record electroencephalogram (EEG), which is the re-sponse of thousands of neurons under the electrodes. They faced each other, but were not allowed to talk to each other. The woman received a heat stimulus on her arm that was moderately painful and was instructed to rate her pain level just before the heat was turned off. On no-touch trials, the man and woman just looked at each other without touching; on touch trials, the man held the woman's hand. There were also trials in which the man was absent. The results showed that the woman's pain ratings were lower when her partner was holding her hand (rating 5 25.0), compared to when he wasn't (37.8) or when he was absent (52.4). This decrease in pain in the hand-holding condition replicates Goldstein's wife's experience in the delivery room. But compar-ing the woman's and man's EEG responses revealed something that wasn't obvious in the delivery room. The woman's and man's brains were strongly "coupled" or synchronized when holding hands (Figure 15.29a), but were not as synchronized when not holding hands (Figure 15.29b). The authors suggest that the support provided by hand holding causes synchronized brain waves, which are translated into reduced pain. In addition to this synchronization effect, other research has shown that hand holding reduces activity in brain areas associated with pain (Lopez-Sola et al., 2019). These experiments have two important messages: Providing support by being there for someone who is experiencing pain can reduce their pain, and making physical contact by holding hands reduces the pain even further.

Describe research by Penfield which led to the mapping of the sensory homunculus, and describe the sensory homunculus.

When Penfield stimulated points on the primary somato-sensory cortex (S1) and asked patients to report what they per-ceived, they reported sensations such as tingling and touch on various parts of their body. Penfield found that stimulating the ventral part of S1 (lower on the parietal lobe) caused sen-sations on the lips and face, stimulating higher on S1 caused sensations in the hands and fingers, and stimulating the dorsal S1 caused sensations in the legs and feet. The resulting body map, shown in Figure 15.5, is called the homunculus, Latin for "little man." The homunculus shows that adjacent areas of the skin project to adjacent areas in the brain, and that some areas on the skin are represented by a disproportionately large area of the brain. The area de-voted to the thumb, for example, is as large as the area devoted to the entire forearm. This result is analogous to the cortical magnification factor in vision (see page 75), in which recep-tors in the fovea, which are responsible for perceiving visual details, are allotted a disproportionate area on the visual cor-tex. Similarly, parts of the body such as the fingers, which are used to detect details through the sense of touch, are allotted Figure 15.5 (a) The somatosensory cortex in the parietal lobe. The primary somatosensory area, S1 (light purple), receives inputs from the ventrolateral nucleus of the thalamus. The secondary somatosensory area, S2 (dark purple), is partially hidden behind the temporal lobe. (b) The sensory homunculus on the somatosensory cortex. Parts of the body with the highest tactile acuity are represented by larger areas on the cortex. (Adapted from Penfield & Rasmussen, 1950) a disproportionate area on the somatosensory cortex (Duncan & Boynton, 2007). A similar body map

Describe research showing connections between the physiological mechanisms for physical pain and the pain of social rejection.

as so far considered effects associated with physical pain—pain caused by heating or shocking the skin. We will now describe something very different—the pain caused by social situations such as social rejection. The question we will be con-sidering is, "What does this social pain—pain caused by social interactions—have in common with physical pain?" The idea that social rejection hurts is well known. When describing emotional responses to negative social experiences, it is common for people to use words associated with physi-cal pain, such as broken hearts, hurt feelings, or emotional scars (Eisenberger, 2012, 2015). In 2003, Naomi Eisenberger and coworkers published a paper titled "Does Rejection Hurt? An fMRI Study of Social Exclusion," which concluded that the dorsal anterior cingulate cortex (dACC; see Figure 15.26) is activated by feelings of social exclusion. They demonstrated this by having participants participate in a video game called "Cyberball," in which they were told that they would be play-ing a ball-tossing game with two other participants, who were indicated by the two figures at the top of the computer screen, with the participant being indicated by a hand at the bottom of the screen (Figure 15.31). Initially, the two other players included the participant in their ball tossing (Figure 15.31a), but then they suddenly ex-cluded the participant and just tossed the ball between themselves (Figure 15.31b). This exclusion caused activity in the partici-pant's dACC, as shown in Figure 15.31c, and this dACC activity was related to the degree ofsocial distress the participant reported feeling, with greater distress associated with greater dACC activity (Figure 15.31d). Other studies provided more evidence for similar physi-ological responses to negative social experiences and physi-cal pain. Activation of the dACC and anterior insula (AI) oc-curred in response to a threat of negative social evaluation (Eisenberger et al., 2011) and when remembering a romantic partner who had recently rejected the person (Kross et al., 2011). Also, taking a pain reliever such as Tylenol not only reduces physical pain but also reduces hurt feelings and dACC and AI activity (DeWall et al., 2010). Results such as these have led to the physical-social pain overlap hypothesis, which proposes that pain result-ing from negative social experiences is processed by some of the same neural circuitry that processes physical pain (Eisenberger, 2012, 2015; Eisenberger & Lieberman, 2004). This idea has not gone unchallenged, however. One line of ay be reflecting things other than pain. For example, it has been suggested that the ACC may respond to many types of emotional and cognitive tasks, rather than being specialized for pain (Krishnan et al., 2016; Wager et al., 2016), or that the ACC responds to salience—how much a stimulus stands out from its surroundings (Iannetti et al., 2013). Another question that has been raised is whether activa-tion of the ACC by both social and physical pain means that the same neural circuits are being activated. This question is similar to a question we considered in Chapter 13, when we considered whether music and language share neural mecha-nisms. One of the points made in that discussion, which is also relevant here, is that just because two functions activate the same area of the brain, doesn't mean that the two func-tions are activating the same neurons within that area. Look back at Figure 13.24 for an illustration of the idea that acti-vation within a particular area can involve different neural networks. Choong-Wan Woo and coworkers (2014) used a tech-nique called multivoxel pattern analysis (MVPA) to look at what is happening inside the brain structures involved in social and physical pain. MVPA was used for the neural mind read-ing experiment described in Chapter 5 in which the pattern of voxel responses to oriented lines was determined to cre-ate computer image decoders for visual stimuli (see Method: Neural Mind Reading, page 114). Woo found that the pattern of voxel responses generated by recalling social rejection by a romantic partner was different from the pattern generated by painful heat presented to the forearm, which why his paper is titled "Separate Neural Representations for Physical Pain and Social Rejection." So which idea is correct? Do social pain and physical pain share neural mechanisms, or are they two separate phenom-ena that both use the word "pain"? There is evidence sup-porting the physical-social pain overlap hypothesis, but there is also evidence that argues against this hypothesis. Because social pain and physical pain are certainly different—it's easy to tell the difference between the feeling of being rejected and the feeling from burning your finger—it is unlikely that mechanisms overlap completely. The physical-social pain overlap hypothesis proposes that there is some overlap. But how much is "some"? A little or a lot? Research to answer this question is continuing.

Discuss how cutaneous receptors differ from the receptors for vision, hearing, and olfaction.

but cutaneous receptors in the skin are distrib-uted over the whole body. This wide distribution, plus the fact that signals must reach the brain before stimulation of the skin can be perceived, creates a travel situation we might call "journey of the long-distance nerve impulses," especially for signals that must travel from the fingertips or toes to the brain.

Discuss how odorant recognition profiles help us to understand the perception of smell.

can help us see when two smells look similar but smell very different think roses vs chocolate for example

Describe evidence that there is a chemotopic map on the olfactory bulb.

certain odors have map around the olfactory bulb to figure out easier what it is.

Discuss how odors can influence attention and performance

certain scents that are associated with words can make the task easier and faster for the person compared to words that are not associated.

Discuss how processing odors is similar to the trichromatic theory of color vision.

each odor has specific amount of ODR which causes senses and brain to determine what the scent is. think trichromatic with way more options.

Differentiate between active and passive touch and describe how each affects perception.

ed expert on marine mollusks. His ability to identify objects and their features by touch is an example of active touch—touch in which a person actively explores an object, usually with fingers and hands. In contrast, passive touch occurs when touch stimuli are applied to the skin, as when two points are pushed onto the skin to determine the two-point threshold. The following demonstration compares the ability to identify objects using active touch and pas-sive touch. Ask another person to select five or six small objects for you to identify. Close your eyes and have the person place an object in your hand. In the active condition your job is to identify the ob-ject by touch alone, by moving your fingers and hand over the object. As you do this, be aware of what you are experiencing: your finger and hand movements, the sensations you are feel-ing, and what you are thinking. Do this for three objects. Then, in the passive condition, hold out your hand, keeping it still, with fingers outstretched, and let the person move each of the remaining objects around on your hand, moving their surfaces and contours across your skin. Your task is the same as before: to identify the object and to pay attention to what you are expe-riencing as the object is moved across your hand. hat information is needed about the object in order to identify it.

Define flavor and discuss how it is affected when olfaction is eliminated. Also discuss the role of oral capture.

flavor is taste and olfaction working together to see what food seems to gustatory sense. when olfaction is eliminated less airflow flavor of food will be greatly reduced. One reason this localization of flavor occurs is because food and drink stimulate tactile receptors in the mouth, which creates oral capture, in which the sensations we experience from both olfactory and taste receptors are referred to the mouth (Small, 2008). Thus, when you "taste" food, you are usually experiencing flavor, and the fact that it is all hap-pening in your mouth is an illusion created by oral capture

Discuss the physiology of flavor perception. Describe how taste and olfaction meet in the mouth and nose and then later in the nervous system.

flavor percpetion has many different parts including taste texture sound smell and how food looks. taste and olfaciton meet with passages of air in that air molecules move from mouth to nose then nervous system has two parts of brain that house smell and taste meet up again to figure out the food.

Describe the social touch hypothesis and discuss research that supports it.

led to the social touch hypothesis, which is that CT afferents and their central projections are responsible for social touch. This was recog-nized as a new touch system that is different from the systems we described earlier in the chapter, which sense the discrimi-native functions of touch—sensing details, texture, vibration, and objects. The CT system, in contrast, is the basis of the affective function of touch—sensing pleasure and therefore often eliciting positive emotions. Line Loken and coworkers (2009) focused on the pleasant aspect of social touch by using microneurography to record how fibers in the skin responded to stroking the skin with a soft brush. Loken found that the stroking caused firing in CT afferents and also in the SA1 and SA2 myelinated fibers as-sociated with the discriminative functions, but with an im-portant difference. Whereas the response of SA1 and SA2 fi-bers continued to increase as stroking velocity increased all the way to 30 cm per second (Figure 15.21a), the response of the CT afferents peaked at 3-10 cm per second and then decreased (Figure 15.21b). CT afferents are therefore special-ized for slow stroking. And perhaps as important, Loken also had participants rate the pleasantness of the sensation caused by this slow stroking and found a relationship between pleas-antness and CT afferent firing (Figure 15.21c). Further re-search showed that maximum pleasantness ratings occurred at stroking speeds associated with optimal CT firing (Pawling et al., 2017).

Discuss how music and color influence flavor.

music for softer music can make flavors smooth while color can affect such as lime flavor but looks red more likely to guess strawberry or cherry flavored.

Discuss how attention affects pain perception.

n occurred not when he was injured but when he realized he was injured. One conclusion that we might draw from this example is that one way to decrease pain would be to distract a person's attention from the source of the pain. This technique has been used in hospitals with virtual reality techniques as a tool to distract attention from a painful stimulus. Consider, for example, the case of James Pokorny, who received third-degree burns over 42 percent of his body when the fuel tank of the car he was repairing exploded. While having his bandages changed at the University of Washington Burn Center, he wore a black plastic helmet with a computer monitor inside, on which he saw a virtual world of multicolored three-dimensional graph-ics. This world placed him in a virtual kitchen that contained a virtual spider, and he was able to chase the spider into the sink so he could grind it up with a virtual garbage disposal (Robbins, 2000). The point of this "game" was to reduce Pokorny's pain by shifting his attention from the bandages to the virtual reality world. Pokorny reports that "you're concentrating on differ-ent things, rather than your pain. The pain level went down significantly." Studies of other patients indicate that burn pa-tients using this virtual reality technique experienced much less pain when their bandages were being changed than pa-tients in a control group who were distracted by playing video games (Hoffman et al., 2000) or who were not distracted at all (Hoffman et al., 2008; also see Buhle et al., 2012)

Discuss how our emotional state can influence pain perception.

n to music. Minet deWied and Marinis Verbaten (2001) had partici-pants look at pictures that had been previously rated as be-ing positive (sports pictures and attractive females), neutral (household objects, nature, and people), or negative (burn vic-tims and accidents). The participants looked at the pictures while one of their hands was immersed in cold (2°C/35.6°F) water, and they were told to keep the hand immersed for as long as possible but to withdraw the hand when it began to hurt. The results indicated that participants who were look-ing at the positive pictures kept their hands immersed for an average of 120 seconds, but participants in the other groups removed their hands more quickly (80 seconds for neutral pic-tures; 70 seconds for negative pictures). Because their ratings of the intensity of their pain—made immediately after removing their hands from the water—was the same for all three groups, deWied and Verbaten concluded that the content of the pic-tures influenced the time it took to reach the same pain level in the three groups. In another experiment, Jaimie Rhudy and coworkers (2005) found that participants gave lower ratings to pain caused by an electric shock when they were looking at pleasant pictures than when they were looking at unpleasant pictures. They concluded from this result that positive or nega-tive emotions can affect the experience of pain. Music is another way to elicit emotions, both positive and negative (Altenmüller et al., 2014; Fritz et al., 2009; Koelsch, 2014). These emotional effects are one of the primary reasons we listen to music, but there is also evidence that the positive emotions associated with music can decrease pain. Mathieu Roy and coworkers (2008) measured how music affected the perception of a thermal heat stimulus presented to the fore-arm by having participants rate the intensity and unpleasant-ness of the pain on a scale of 0 (no pain) to 100 (extremely intense or extremely unpleasant), under one of these three con-ditions: listening to unpleasant music (example: Sonic Youth, Pendulum Music), listening to pleasant music (example: Rossini, William Tell Overture), and silence. The results of Roy's experiment for the highest tempera-ture used (48°C/119°F), shown in Table 15.3, indicates that listening to unpleasant music didn't affect pain, compared to silence, but that listening to pleasant music decreased both the i ntensity and the unpleasantness of pain. In fact, the pain relief caused by the pleasant music was comparable to the effects of common analgesic drugs such as ibuprofen.

Apply the previously-learned terms of cortical magnification, plasticity, and receptive fields to the somatosensory system.

receptive fields are how much of a receptor takes up of processing while plasticity means adapting to an everchanging environement cortical magnificaiton means how many receptors are used to perceive an object(think fovea and how important that is for vision)

Define tactile acuity and describe methods used to measure tactile acuity.

tactile acuity—the capacity to detect details of stimuli presented to the skin. . The classic method of measuring tactile acuity is the two-point threshold, the mini-mum separation between two points on the skin that when stimulated is perceived as two points (Figure 15.7a). The two-point threshold is measured by gently touching the skin with two points, such as the points of a drawing compass, and hav-ing the person indicate whether he or she feels one point or two. The two-point threshold was the main measure of acuity in most of the early research on touch. Recently, however, other methods have been introduced. Grating acuity is measured by pressing a grooved stimulus like the one in Figure 15.7b onto the skin and asking the person to indicate the orientation of the grating. Acuity is measured by determining the narrowest spacing for which orientation can be accurately judged. Finally, acuity can also be measured by pushing raised patterns such as letters onto the skin and determining the smallest sized pattern or letter that can be identified

Describe how odor detection thresholds are measured.

the forced-choice method, in which participants are presented with blocks of two trials—one trial contains a weak odorant and the other, no odorant. The participant's task is to indicate which trial has a stronger smell. The threshold is determined by measuring the concentration that results in a correct re-sponse on 75 percent of the trials (50 percent would be chance performance).

Use the gate control model of pain to explain why rubbing your elbow after banging it makes it hurt less.

the neruons around injury will be focused on rubbing instead of pain from injury esssentially confusing the nerves and distract from the pain which can be very helpful

Describe multimodal interactions.

two or more senses working at the same time think eating having smell and taste together seeing someones face and hearing their voice giving someone a hug while listening to a concert

Describe the processes involved when smelling coffee, orange juice, and bacon at the same time, and relate this process to the concept of odor objects.

ve the odors of individual molecules; we perceive "coffee." The feat of perceiving "coffee" becomes even more amaz-ing when we consider that odors rarely occur in isolation. Thus, the coffee odor from the kitchen might be accompa-nied by the smells of bacon and freshly squeezed orange juice. Each of these has its own tens or hundreds of molecules, yet somehow the hundreds of different molecules that are floating around in the kitchen become perceptually orga-nized into smells that refer to three different sources: coffee, bacon, and orange juice (Figure 16.14). Sources of odors such as coffee, bacon, and orange juice, as well as nonfood sources such as rose, dog, and car exhaust, are called odor objects. Our goal, therefore, is to explain not just how we smell different odor qualities, but how we identify different odor objects. Perceiving odor objects involves olfactory processing that occurs in two stages. The first stage, which takes place at the beginning of the olfactory system in the olfactory mucosa and ol-factory bulb, involves analyzing. In this stage, the olfactory system analyzes the different chemical components of odors and trans-forms these components into neural activity at specific places in the olfactory bulb (Figure 16.15). The second stage, which takes place in the olfactory cortex and beyond, involves synthesizing. "Coffee" "OJ" In this stage, the olfactory system synthesizes the information about chemical components received from the olfactory bulb into representations of odor objects. As we will see, it has been proposed that this synthesis stage involves learning and mem-ory. But let's start at the beginning, when odorant molecules enter the nose and stimulate receptors on the olfactory mucosa

Which one is associated with controlling handgrip?

Meissner corpuscle

a) Which one is rapidly adapting and deep in the skin?

Meissner corpuscle

a) Which two fire to on and off pressure?

Meissner corpuscle and Pacinian corpuscle

a) Which one is associated with the perception of shape?

Merkel receptor

a) Which one is slowly adapting and close to the surface of the skin?

Merkel receptor

a) Which two have smaller cutaneous receptive fields?

Merkel receptor and Meissner corpuscle

a) Which two fire to continuous pressure?

Merkel receptor and Ruffini cylinder

Define anosmia.

Anosmia means loss of smell normally after traumatic brain injury or COVID19 which is becoming common.

Explain how opioids, endorphins, and placebos affect the perception of pain.

Another important development in our understanding of the relationship between brain activity and pain perception is the discovery of a link between chemicals called opioids and pain perception. This can be traced back to research that began in the 1970s on opiate drugs, such as opium and heroin, which have been used since the dawn of recorded history to reduce pain and induce feelings of euphoria. By the 1970s, researchers had discovered that opiate drugs act on receptors in the brain that respond to stimulation by molecules with specific structures. The importance of the mol-ecule's structure for exciting these "opiate receptors" explains why injecting a drug called naloxone into a person who has overdosed on heroin can almost immediately revive the victim. Because naloxone's structure is similar to heroin's, it attaches to the same receptor sites, thereby preventing from binding to those receptors (Figure 15.27a). Why are there opiate receptor sites in the brain? After all, they certainly have been present since long before people started taking heroin. Researchers concluded that there must be naturally occurring substances in the body that act on these sites, and in 1975 neurotransmitters were discovered that act on the same receptors that are activated by opium and heroin. One group of these transmitters is called endorphins, for en-dogenous (naturally occurring) morphine. ulated a large amount ofevidence linking endorphins to pain reduction. For example, pain can be decreased by stimulating sites in the brain that release endorphins (Figure 15.27b), and pain can be increased by injecting naloxone, which blocks en-dorphins from reaching their receptor sites (Figure 15.27c). In addition to decreasing the analgesic effect of endor-phins, naloxone also decreases the analgesic effect of placebos (see page 375). This finding, along with other evidence, led to the conclusion that the pain reduction effect of placebos oc-curs because placebos cause the release of endorphins. As it turns out, there are some situations in which the placebo effect can occur without the release of endorphins, but we will focus on the endorphin-based placebo effect by considering the fol-lowing question, raised by Fabrizio Benedetti and coworkers (1999): Where are placebo-related endorphins released in the nervous system? Benedetti wondered whether expectation caused by pla-cebos triggered the release of endorphins throughout the brain, therefore creating a placebo effect for the entire body, or whether expectation caused the release of endorphins only at specific places in the body. To answer this question, Benedetti injected participants with the chemical capsaicin just under the skin at four places on the body: the left hand, the right hand, the left foot, and the right foot. Capsaicin, which is the active component in chili peppers, causes a burning sensation where it is injected What this means, according to Benedetti, is that when (b) Endorphin Naloxone Increases pain by blocking endorphins (c) Figure 15.27 (a) Naloxone, which has a structure similar to heroin, reduces the effect of heroin by occupying a receptor site normally stimulated by heroin. (b) Stimulating sites in the brain that cause the release of endorphins can reduce pain by stimulating opiate receptor sites. (c) Naloxone decreases the pain reduction caused by endorphins by keeping the endorphins from reaching the receptor sites. participants direct their attention to specific places where they expect pain will be reduced, pathways are activated that re-lease endorphins at specific locations. The mechanism behind endorphin-related analgesia is therefore much more sophis-ticated than simply chemicals being released into the overall circulation. The mind, as it turns out, can not only reduce pain by causing the release of chemicals, it can literally direct these chemicals to the locations where the pain would be occurring. Research such as this, which links the placebo effect to endor-phins, provides a physiological basis for what had previously been described in strictly psychological terms.

Discuss which view, population coding or specificity coding in taste, is most accepted at this time.

Because of arguments such as this, some researchers be-lieve that even though there is good evidence for specific taste receptors, population coding is involved in determining taste as well, especially at higher levels of the system. One suggestion is that basic taste qualities might be determined by a specific code, but population coding could determine subtle differences

Which one is associated with perception of stretching of the skin?

Ruffini cylinder

a) Which one is slowly adapting and deep in the skin?

Ruffini cylinder

Which two are located deeper in the skin?

Ruffini cylinder and Pacinian corpuscle

Which two have larger cutaneous receptive fields?

Ruffini cylinder and Pacinian corpuscle

Identify the five basic taste qualities.

Salty, sweet, umami(meaty)related to MSG, sour, and bitter. These are all important to taste.

Describe the structure of taste buds.

Taste bud=50-100 taste cells Individual differences Not at all hate coffee Lots of cream and sugar Black has neve fiber taste cell and taste pore included

Discuss the major principles of the gate control model of pain.

The gate control model begins with the idea that pain signals enter the spinal cord from the body and are then transmitted from the spinal cord to the brain. In addition, the model proposes that there are additional pathways that influence the signals sent from the spinal cord to the brain. The central idea behind the theory is that signals from these additional pathways can act to open or close a gate, located in the spinal cord, which determines the strength of the signal leaving the spinal cord. Figure 15.24 shows the circuit that Melzack and Wall (1965) proposed. The gate control system consists of cells in the dorsal horn of the spinal cord (Figure 15.24a). These cells in the dorsal horn are represented by the red and green circles in the gate control circuit in Figure 15.24b. We can under-stand how this circuit functions by considering how input to the gate control system occurs along three pathways: ■ Nociceptors. Fibers from nociceptors activate a circuit con-sisting entirely of excitatory synapses, and therefore send excitatory signals to the transmission cells. Excitatory signals from the (+) neurons in the dorsal horn "open the gate" and increase the firing of the transmission cells. Increased activity in the transmission cells results in more pain. ■ Mechanoreceptors. Fibers from mechanoreceptors carry information about nonpainful tactile stimulation. An ex-ample of this type of stimulus would be signals sent from rubbing the skin. When activity in the mechanoreceptors reaches the (-) neurons in the dorsal horn, inhibitory signals sent to the transmission cells "close the gate" and 374 CHAPTER 15 The Cutaneous Senses Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Figure 15.24 (a) Cross section of the spinal cord showing fibers entering through the dorsal root. (b) The circuit proposed by Melzack and Wall (1965, 1988) for their gate control model of pain perception. See text for details. decrease the firing of the transmission cells. This de-crease in firing decreases the intensity of pain. ■ Central control. These fibers, which contain information related to cognitive functions such as expectation, atten-tion, and distraction, carry signals down from the cortex. As with the mechanoreceptors, activity coming down from the brain also closes the gate, decreases transmis-sion cell activity, and decreases pain. Since the introduction of the gate control model in 1965, researchers have determined that the neural circuits that con-trol pain are much more complex than what was proposed in the original model (Perl & Kruger, 1996; Sufka & Price, 2002). Nonetheless, the idea proposed by the model—that the perception of pain is determined by a balance between input from nociceptors in the skin and nonnociceptive ac-tivity from the skin and the brain—stimulated research that provided a great deal of additional evidence for the idea that the perception of pain is influenced by more than just stimu-lation of the skin (Fields & Basbaum, 1999; Sufka & Price, 2002; Turk & Flor, 1999; Weissberg, 1999). We will now con-sider some examples of how cognition can influence the per-ception of pain.

List three cognitive factors that affect pain perception.

expectation, attention, emotions

Define taste, olfaction, and flavor.

flavor is combination of olfaction and taste. taste, which occurs when molecules—often associated with food—enter the mouth in solid or liquid form and stimulate receptors on the tongue (Figure 16.1); olfaction, which occurs when air-borne molecules enter the nose and stimulate receptor neu-rons in the olfactory mucosa, located on the roof of the nasal cavity;

Compare how odors are represented in the olfactory bulb to how they are represented in the piriform cortex.

in olfactory bulb there is a chemotpic map that helps the receptors work well. Piriform cortex has no map which means organization is very different.

Note locations for the taste and olfactory cortical areas.

olfactory cortex and gustatory cortex both have to do with taste and smell insula also has to do with chemical senses these are really important

Describe how cognitive factors influence flavor.

price of an item can affect the flavor presentation of food depending on serving utensil and plate bowl etc name of food can also greatly influence flavor for the person.

Describe sensory-specific satiety.

sensory specific satitety means that certain foods with certain sense features will get old very quickly such as bananas when eating to super fullness.

Define specificity and population coding.

specificity coding, the idea that quality is signaled by the activ-ity in individual neurons that are tuned to respond to specific qualities; and population coding, the idea that quality is signaled by the pattern of activity distributed across many neurons.

Describe evidence for population coding in taste.

specificity coding, the idea that quality is signaled by the activ-ity in individual neurons that are tuned to respond to specific qualities; and population coding, the idea that quality is signaled by the pattern of activity distributed across many neurons.

Discuss taste and smell as gatekeepers. Also discuss the neurogenesis of taste and smell receptors.

taste and smell show what thing should be consumed and what should not be consumed due to spoilage poison etc. Taste and smell receptors are born created and die rapidly. olfactory recpetors 5-7 weeks while taste receptors 1-2 weeks.

Discuss the functions of olfaction in different species.

to be able to scent out where they are and find things if needed right then.

Describe evidence for specificity coding in taste.

y), hydrochloric acid (HCl; sour in low concentra-tions), and quinine (QHCl; bitter) (Lundy & Conteras, 1999). The neuron in Figure 16.8a responds selectively to sucrose, the one in Figure 16.8b responds selectively to NaCl, and the neuron in Figure 16.8c responds to NaCl, HCl, and QHCl. Neurons like the ones in Figures 16.8a and 16.8b, which re-spond selectively to stimuli associated with sweetness (sucrose) and saltiness (NaCl), provide evidence for specificity coding. Neurons have also been found that respond selectively to sour (HCl) and bitter (QHCl) (Spector & Travers, 2005).